CA2188893A1 - Combined reformulation/packaging to delay staling in bakery products - Google Patents

Abstract

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Description

~:' 218~893 COM~INED REFORMULATION/PACKAGING TO DELAY STALING
IN BAXERY PRODUCTS.

BACKGROUND OF THE INVENTION

The present invention relates to a method for delaying staling in backery products, which combined reformulation and modified atmosphere packaging. The importance of the bakery industry is well known worldwide. Bakery products are an important source of nutrients in our diet. Consumption of bakery products in North America is estimated at $23 billion dollars annually with roughly 50~ being spent on bread and rolls (Peat Marwick Group, l991).However, spoilage occurs shortly after baking. After microbial spoilage, the main spoilage problem is staling.
Therefore, methods to control staling are of great importance to the bakery industry since staling results in millions of dollars annually in lost revenues. It was already reported that returns due to staling in the United States are 8% accounting for almost 50 million kg. of product returns annually. To overcome this major spoilage problem, staling of bakery products has been the subject of extensive investigation.
Two approaches to delay staling has been investigated so far. The first approach is through packaging under a modified atmosphere involving elevated CO2 levels. While packaging under 100~ CO2 delays both mold growth and staling for 6 weeks, products are rejected by consumers after 4 weeks due to the sharp acidic taste of CO2 dissolved in the aqueous phase of the product.
The other and more successful approach is through reformulation involving various gums, surfactants, high fructose corn syrup (HFCS enzymes and low protein flours. Results showed that a highly acceptable product from both a textural and sensorial viewpoint could be produce commercially through appropriate levels of enzyme, gum and HFCS in the formulation. The present invention combine both of these known technologies. As a matter of fact, it is based on this discovery that staling and mold growth can be prevented / delayed in bagels or any other bakery products for at least 6 weeks through appropriate reformulation and modified atmosphere packaging (MAP) using an oxygen absorbent.
The estimated cost for this shelf life extension is 20-30 cents/
dozen bagels. However, the increased costs could be defrayed through less returns and downgrading of products to croutons, 218~8g3 less production costs through bulk processing/ packaging and most importantly extended shelf llfe, market growth and increased profitability. Yet another cost cutting approach would be to use the new generation of oxygen sca~enging films which are gradually appearing on the marketplace.
Several definitions of staling have been proposed. Bechtel et al.
(1953) defined staling as a" decreasing consumer acceptance of bakery product caused by changes in the crumb and the crust other than those resulting from the action of spoilage microorganisms".
According to Bechtel and Meisner (1951) consumers view staling as hardening of the crumb which has a dry mouth feel, an increase in crumbliness, a loss of flavor and aroma, and a softening and toughening of the crust". KuIp (1979) stated that staling was ~Ithe gross changes and the various undertying reactions, as well as other physical or chemical phenomena which contribute to the subjective estimate known as staling".
Staling begins immediately after the baking process is complete (Hebeda et al., l9gO). It leads to an increase in crumb firmness, a loss of product freshness and of consumer acceptance. However, the process can be delayed through appropriate formulation changes using surfactants, gums, enzymes, high fructose corn syrup and flours of different gluten content, either a]one or in conjunction with each others.

In accordance with the invention, it has been found that combined ~eformulation and packaging offers the baking industry a viable approach to inhibit two potential spoilage concerns staling and mold growth. However, further studies are required to determine the public health safety of these reformulated bakery products, particularly with respect to the growth of Clostridium ~otulinum in bagels stored under reduced oxygen tensions and at room temperature.
Staling has been extensively studied in the past century, and many theories have evolved. However, despite these theories, research is still ongoing in an attempt to extend the shelf life of the bakery products with respect to staling. Several methods have been investigated to increase the mold free shelf life of bakery products. These include:
- Good manufacturing practices, (Jenkins, 1975).
- U.V. light and microwave heating, (Black, 1993~.
- Incorporation of preservatives such as sorbic and proprionic acid: or calcium salts either directly into the product or sprayed on the product surface, (Seiler, 1989).
- Freezing, ~Matz, 1992).
- Modified atmosphere packaging, ~MAP), involving gas packaging with mixtures of ~-O~ and N~ oxygen absorbents and ethanol vapor generators ~Smith and Simpson, 1996).

2~893 ' ~_ Water activity is one of the main factors affecting the shelf life of the bakery products. It is directly related to microbial spollage.
Bakery products can be divided into three major groups on the basis of their water activity (a ):
- low moisture bakery products. i.e., products with an aw of less than 0.6 (aw < 0.61. This group is the least affected by lOmicrobial growth;
- intermediate moisture bakery products having an aw between 0.6 and 0.85 (aw 0.6-0.85) - high moisture products with an ah higher than 0.85, usually between 0.95 and 0.99 (aw 0.g5-0.99). This group is most affected by microbial growth. ~Smith and Simpson, 1995) Bakery products, like all processed food products, are subject to spoilage.
20Spoilage of bakery products can be divided into:
- microbial spoilage - chemical spoilage - physical spoilage (Smith and Simpson, 1995) Chemical spoilage involves both oxidative and hydrolytic rancidity problems.
A rancid product has a musty, rank taste or smell due to fats that have oxidized and decomposed with the liberation of short chain fatty acids, aldehydes and ketones through an autolytic 30free radical mechanism. The free radicals and peroxides can bleach pigments, destroy vitamins A and E, breakdown proteins and cause darkening of fat (Smith and Simpson, 1995). They also have a disagreable odor and flavor and are toxic in large amounts.
This kind of rancidity occurs in the absence of oxygen. It results in the hydrolysis of triglycerides and the release of glycerol and short chain fatty acids.
Microbial spoilage comprises of bacterial, yeast and mold 40spoilage (Smith and Simpson, 1995). All microorganisms require three basic elements: food, temperature and moisture. Pre-packaged bakery products provide conditions conducive to microbial growth tJenkins, lg75).Mold spoilage is responsible for the majority of losses in the bakery industry in the United States.
The majority of the molds found in white ~read belong to the genus Aspergillus and Penicillium ~Hartung, et al., 1973). Other mold species e.g., Rhizopus, Monilia, and Mucor species have also 50been implicated (Jenkins, 1975). According to Bullerman and Hartung ~1973), aLlatoxin producing molds have never been detected in either flour or bread. They also stated that flour 8~'8g3 contained more toxic molds than bread, due to the fact that mold spores are not very heat resistant. Thus, mold spoilage results from postprocessing contamination. This occurs during cooling and packaging from contamination by airborne spores or contact with contaminated surfaces (Black, 1993). Contamination also results from food handlers and raw ingredients such as glazes, nuts, spices and sugars ISmith, 1994). Under warm humid conditions, mold problems are even more trouhlesome and mold growth is visible within 48 hours after baking and packaging (Black, 1993~.
Physical spoilage usually involves moisture loss or gain and staling. Moisture loss or gain is a problem in both high and low moisture products. Loss of moisture in high moisture bakery products results in a loss of texture and firmness. A gain of moisture in low moisture products also results in textural changes and may promote enzymatic and microbial spoilage problems. Both moisture loss and gain can be prevented by packaging products in a film which is a high barrier to moisture e.g., low density polyethylene ILDPE1 By definition, bread staling refers to all the changes that occur in bread after baking. The consumer perceives staling of bread by changes in the aroma, toughening of the crust and, most importantly, firming of the crumb (Bechtel et aI,, 1951). Based on market studies, the wholesale baking industry believes that consumers equate "squeeze" softness with freshness and make their choice at the supermarket bread rack accordingly ~ackel, lg~9~.
Thus, the bakery industry attempts to produce the most "squeezable" bread (Jacket, 1989). Objective measurements of 30staling are complicated since 'Istaleness of bread is a subjective quality which is ultimately assessed by the senses" (Toufeili et al., 1994). Under optimal storage conditions, bread llstales after 2-3 days on supermarket shelves IJackel, 1989).
Staling can be divided into crust staling and crumb staling. The majority of research has focused on crumb staling as crust staling seems impossible to prevent.
Crust staling is due to moisture migration from the crumb to the 40cnlst and from absorption of moisture from the atmosphere if the relative humidity (RH) is high i.e., RH>80'~ (KuIp, 1979). If the bread is left unpacked, it dries out completely. If packaged, the crust soon stales (KuIp, 1979~. Crust staling is enhanced by high moisture barrier packaging materials which do not permit moisture to pass from the crumb to the atmosphere. Thus, it remains in the crust IMaga, 1975).
Crumb staling is an even more complex phenomenon. The crumb becomes firmer, less elastic, cn~mblier, harsh textured, and it 50has a dry mouth feel ~KuIp, 1979). The main factors affecting staling are shown in table 1.10.

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Several methods have been developed to retard staling. These include:
the addition of shortenings, the use of mono and diglycerides, surfactants, enzymes, gums, gluten free flour. (Table 2.3) Shortening can be defined as a "an edible fat used to shorten 50baked goods" ~Merriam Webster's Collegiate Dictionary, 1995).

' 21~889 5~ .
' ~_ Table 2.3.: I"~ dients used in lhe reformulalion and lheir pe~ nl~es~
ll~y~ 3l~ls Trade Name Suppller ~r~el~l g,ls used Cr~ "l~s:
Genell~ y ",odlriedNovamyl Novo Nordlsk 0.031, 0.047 t~n ~ a-an"~l~se (Danbury, Ct~
i ungal and baclerlal Su~,errle~l, plus Enzyme Dl~s(e",s 0.1, 0.15, 0.2 ~-a",ylas~s (BeloH, Wl) Bac~erialc~-&""~las~hl~yal,esllplusEnzyme Bklayslems0.1 0.15 0.2 and gl~-;ul~l,a~erase (Beloil, Wl) Gums:
Guar GuarSG25 Amcan IIl~ i . nla 0.2 0.6 1 (Lachlne, QC) Xanthan Xanthan 100 Amcan Illyl~ i'E.115 0.2, 0.6,1 (Lachlne, QC) Locusl bean LBG SG14 Amcan Iny,ed ~nls 0.2, 0.6, 1 (i achine, QC) Agar Agar Agar Amcan Inyledlenls 0.2, 0.6, 1 (Lachlne, QC) Cellulose Cellulose40 Soca Floc(Chlcago, IL) Cellulose 300 Soca Floc (Chlca~o, IL) Cellulose 900 Soca Floc(Chicago, IL) M~ lc~lulose Mi~ll,ocel Dowl"y~ ier,ls ,(Midland, Ml) Algln Kelvls l<elco (Chlcago, IL) 0.2, O.ff, 1 Peclin Classic AB201 1 IErl,sl,~ oxl 0.2, 0.6,1 Amcan Illsll~d ~nls (Lachine, QC) SYru~s2:
HFCS Liquld HFCS Llquld ADM Corn P~ essl"g 50,100 (Decalur, AL) H~CS Granular HFCS Granular ADM Corn Processl~,~ 50,1~0 (Decalur, AL) Fhur:
Rice InslanlRice Flour IGT (Lincoln, NE) 25 Barley Inslanl BarleyFlourIGT (Lincoln, NE) 25 Com Instanl Corn Flour IGT (Lincoln, NE) 50 Surfact~nts:
Sodium Slearoyl Allas SSL ICI su,ra :ta"ts 0.25, 0.375 Laclylale (Lachlne, QC~
SSL and a",~rlaseAllas p51 ICI Sur~actanls 0.25, 0.375 (Lachine, QC) 1: Based on a ~lour welght basis.
2: Based on a su~ar ,eplace"~enl basis.

~188893 . ~

Most researchers agree that shortening, fat, or a combination of vegetable oil and emulsifiers is an essential ingredient in bread making. In commercial bakeries these are added to facilitate dough handling and processing, to improve loaf volume and crumb grain; and to prolong shelf life (Pomeranz et al., 1991~. When shortening is used in the formulation an increase in loaf vol~e, an improvement in crumb grain and a retardation of crumb firming - during storage was observed. Crumb color depends to a large extend on loaf volume and crumb grain (Pomeranz et al., 1966).
10However, adding shortening had no significant effect on water absorption and mixing time.
Wheat flour lipids are important functional components in baking since shortening acts through these lipids (Rogers et al., 1988).
Shortening had no effect on firming rate of bread made with defatted flour ~Rogers et a/.,1 988). Defatting significantly reduced volume and softness of bread as well as impairing loaf volume and crumb grain of bread baked from the flour (Pomeranz et al., 1991~. This effect is related to the amount of polar 201ipids removed from the flour during defatting. However, the effects of shortening or of polar lipids on bread quality were independent of wheat class or variety. Many f]ours were tested and, in all cases, shortening resulted in improved products with poor flour quality being improved the most (Pomeranz et al., 1966).
The influence of shortening on firming rate is concentration dependent ~Rogers et al., lg8B). Usually 23% shortening has shown to be effective in providing the highest volume and softness of 30bread (Rogers et al., 1988; Pomeranz et aL, 1991). Higher levels had no additional improving effect (Pomeranz et al., 1966). It appears that wheat flour protein governs breadmaking properties.
Lipids, however, seem to provide certain functional properties.
Once those requirements are met, no additional benefits can be derived by adding more lipid (Pomeranz et a~., 1966). This lipidprotein interaction affects both the firming rate and the loaf volume (Rogers et at, 1988). It has also been shown that 1 or 2% soy or corn oil produced bread with a volume comparable to that with 2~ shortening ~Pomeranz et at, l99l).
Surfactants aid in the development of less tacky, more extensible doughs which process through machinery without tearing or sticking, or which result in baked products with finer crumb structure and improved volume and shape. Since 1988, ~103 million kg of surfactants have been used as foods additives, a level which is expected to increase by 5% annually ~kamel, 1993~.

Surfactants are generally used for the following reasons:
l.To promote crumb softness;
2.To strengthen dough for good handling properties;

~ 218883~

3.To aid in water retention; and 4.To improve loaf volume.
In aqueous systems, amylose adopts a helical conformation with the hydrogen atoms oriented to the inner side of the helix. This result in a lipophylic region ideally suited for complex formation with a long chain fatty acid (Osman et al., 1961).
Thus, the crumb softening effect was attributed to the surface active properties of surfactants and their ability to form 10complexes with the amylose fraction of starch ~Figure 1.5). The formation of these complexes with amylose affects the transfer of water between crystallizing starch and gluten which takes place during aging of bread. The softener complexes not only with amylose but also with some of the outer chains of amylopectin (KuIp, 1979).
The substantially low complex forming capacity of amylopectin has been attributed to its limited capacity to form a helix. It has been reported that when more than l~i monoglycerides are added and 20the free amylose is bound, interaction with the amylopectin fraction then occurs (Hani, 1992~.
Surfactants have also been shown to act in a similar manner as flour polar lipids. These are bound to glutenin by hydrophobic bonding between the hydrocarbon chain of the lipid and the lipophylic region of the protein, and to gliadin by hydrogen bonding or electrostatic bonds between the polar groups of the lipid and polar regions of the proteins. The binding of surfactants to gliadin and glutenin enhances the gas retention 30capacity of gluten and results in a larger loaf volume (Hani, 1992).
The emulsifying properties of surfactants result in a more uniform distribution of water throughout the dough and allow for the development of gluten structures with optimum mechanical properties. However, Pisesookbunterng and D' Appolonia (1983) observed that the adsorption of surfactants onto the starch surface, as well as the complex formation between starch and surfactant, prevented starch from absorbirlg water released from 40gluten during bread aging. Consequently, the water released from the gluten was available to migrate from the crumb to the crust of the bread promoting crust staling.
A controversy still exists as to whether surfactants affect initial crumb firmness (Zobel, 1973) or if, as noted by Ghiasi et al. (1982), they only slow the rate of stallng during storage or both effects occurs (Valjakka et aL, 1994).
Sodium tearoyl-2-lactylate,calcium stearoyl-2-Iactylate,lard, 50monoglycerides and tartaric acid ester of sucrose are the most often employed to delay staling (Zobel, 1973). However, Krog (1970) reported that distilled monoglycerides had the best 218~93 complexing ability among nonionic surfactants and that sodium stearoyl-2-lactylate (SSL) and calcium stearoyl lactylate were best among the ionic ones.
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~ncl~ )rep~l~llul~ xl~ lllly Many enzymes can be added to dough to enhance its properties.
Some of the enzymes commercially used in bread dough are a -amylases,~ -amylases, invertases, maltases, zymases and proteinases.(Table 1.12 ) Other enzymes which could be used include lipoxygenases, pentosanases and others.Since amylases and glucoamylases are most often used, their mode of action will be discussed in more detail.
Amylases are divided into a-amylases and ~-amylases. These can be of different sources: bacterial,fungal or cereal. Different sources give enzymes with different properties. Amylases are usually added to increase the level of fermentable sugars, to 40increase the production of simple sugars leading to a sweeter product and better color, since the reducing sugars produced react with other components in bread to give Maillard reaction products. They also improve gas and moisture retention properties of the dough. Furthermore, heat stable amylases retard bread staling.
Schultz et el. ~lg52) reported that small amounts of bacterial amylases had a beneficial softening effect in bread whereas high levels resulted in unacceptable softness. They stated that the 50main advantage of bacterial a-amylase was its thermostability since its action occurs once starch has gelatinized. Miller et al. (1953) studied the effect of fungal, cerea] and bacterial ~, amylases and confirmed the results of Schultz et aL (1952~ noting that all three types resulted in softer brea~ compared to the control bread. Bacterial amylases did not affect the initial bread firmness, but reduced the firming rate during storage.
Conversely, fungal amylases, decreased the initial bread firming but did not affect the firming rate ~Valjakka et al., 199~).
~-amylases are the most widely used en%ymes. Bacterial ~-amylases, survive baking in contrast to cereal and fungal enzymes 10and are commercially used as antistaling agents. However, excessive amounts can produce adverse effects during storage.
Bread can turn gummy and lose desirable textural properties due to the thermostable property of the enzyme. New improved bacterial amylases with reduced thermostability have been introduced to prevent these problems occurring during storage.
Bacterial a-amylase cleaves linkages in the amorphous regions of starch where they are most accessible to enzyme attack. Once the enzyme complexes with the starch mo]ecule and the initial 20cleavage has been made, the enzyme may remain with one fragment and produce one or more breaks before dissociating and moving to another substrate molecule (Martin and Hoseney, lgglb~. Prior to baking, they only digest the damaged starch ~5~). On the other hand, bacterial and fungal ~amylases produce small dextrins that interfere with hydrogen bonds formation ill starchprotein interaction and, thus, retard bread firming (Valjakka et al., lg94) ~ -amylase is an exoenzyme. It releases two joined glucose unit 30~maltose) from starch. amylase is normally present in flour so that addition supplementation is not required. Still, the addition of aamylase will enhanci the action of ~ amylases since it will produce small dextrins on which ~-amylase can readily act.
Glucoamylase is an exoenzyme which works on the nonreducing end C a starch chain and releases glucose molecu]es in a step wise process. It used in bread for glucose production since it results in a sweeter product compared to maltose produced by ~-amylase.
Two other major groups of enzymes can also be used: non-starch polysaccharide degrading enzymes, and the lipid modifying enzymes. The non-starch polysaccharide enzymes consist mainly of hemicellulases and pentosanases that have been shown to have some effect retarding staling. The lipid modifying enzymes group include lipoxygenases lipases and phospholipases.
These have also been the subject of many studie and appear to have an effect on bread firming. The action of lipoxygenaseE such as soy lipoxygenase, appear to be related with gluten 50development. It was proposed that the action of lipoxygenase involves modification of the hydrophobic areas o~ the gluten ~KuIp and Ponte, 1981~. It was assumed that the release of gluten . ~_ 2188893 bound lipids will provide additional free lipids for complexing with starch during baking leading to a softer bread.
Maga (lg75) reported studies on gum carrageenan and gum karaya an reported that they could have an antistaling effect.
Christianson and Gardner (1974) studied the effect of xanthan gums in protein fortified starch bread. However, they found no effect on bread firming. Mettler and Seibel(1993) worked with guar gum carboxymethyl cellulose, mono and diglyceride and 10diacetyl tar-taric ester of monoglycerides. Their results showed that gums had some effects in retarding the staling process.
The effect of gums on staling have not been investigated extensively Further studies are required to determine if they play an important role as anti- staling agents.
Most studies to date have examined the effect of softening agents individually. However, combination treatments with these agents could have a more pronounced effect on sta]ing.
As mentioned previously, the combination of mono and diglycerides did not appear to give favorable results. However, emulsifiers have been added with shortening to defatted flours to give better results. For example, 0.1 % of ethoxylated monoglyceride ~EMG) and 0.2~ hydroxylated lecithin, alone or in combination with 2~
shortening increased volume and improved softness of bread: each was superior to shortening alone. EMG primarily strengthened the dough and increased bread volume, and lecithin improved rheological properties of the dough and crumb grain texture 30~Pomeranz et at., 1991).
The combination of an enzyme and an emulsifier resulted in a less firm bread than bread in which these additives were used separately ~Pomeranz e at., 1991). However, they did not have a synergistic interaction on bread firmness of white pan bread.
Some reports indicated that enzymes alone have little effect on bread staling, and that emulsifiers alone increase bread softness Others have reported that when bacterial aamylase was added to the dough together with crumb softener emulsifiers, such as 40monoglycerides, firming rate was greatly reduced. However, Valjakka et at. ~1994) did not find major interactions between enzymes and surfactants.
Martin and Hoseney ~199lb) reported that the amylose-lipid complex was shown to be an obstacle to starch hydrolysis with glucoamylase. The initial velocity of reducing end groups released by the action of amylase was lower in the presence of 10% monoglycerides. Starch granules were less swollen in the presence of a monoglyceride, which may have decreased the rate 50vf hydrolysis. However, their results showed that the monoglyceride did not function by affecting the thermal stability of the amylases. In a system with high levels of ~ -amylase, monoglycerides seemed to reduce ~ -amylase activity, while bacterial ~-amylase overcame the effect of monoglycerides on ~-amylase activity.
Combination of many enzymes have been patented, such as debranching enzymes ~acting on the a(1,6 ) linkages with amylases. Bacterial and fungal amylases in combination have a synergistic effect on softening. A glucoamylaseamylase preparation, able to digest native starch rapidly has been lOdeveloped in Japan. It is an enzyme originating from Aspergittus K27. It has 70~ glucoamylase and 30~ ~-amylase activity and ;s able to hydrolyze native corn starch comp]etely within 24 hours.
Combination of raw starch digesting enzymes and amylases led to the conclusion that the degradation of raw starch granules is due mainly to the glucoamylase activity, while ~amylase exert a synergistic action (Valjakka et at., 1994).
The reduction in bread firmness due to enzymatic action has been discussed by Dragsdorf and Varriano-Marston (~980). 'rhey showed 20that bread supplemented with bacterial amylases to be the softest during storage. They noted that bread supplemented with barley, malt or fungal enzyme showed the same initial softness as the fresh product. Furthermore, they observed an order of decreasing degree of starch crystallinity from bacterial a-amylase, cereal ~ -amylase, fungal a -amylase and unsupplemented bread, postulating that the degree of crystallinity paralleled the heat stability of the enzyme, which produce lower molecular weight starch units. These will have more freedom of movement and can more easily arrange themselves into lattice position. Thus, they 30indicated that starch crystallinity and bread firming were not synonymous.
Martin and Hoseney (1991) also observed that bacterial ~ -amylase and ~-amylase inhibited bread from firming during five days of storage. Bread supplemented with amylases contained great quantities of dextrins which appear to have an anti-firming effect. Valjakka et al. (19g4) showed that bacterial amylases reduced the firming rate of bread and that the rate of firming increased with increasing concentration of enzyme confirming our 40Observations. They noted that excessive amount of the enzymes could lead to keyholing ~weakness of loaf side walls). However, this defect was not observed for bagels. Finally, Akers and Hoseney (lg94) recently reported the positive effect of enzymes on bread staling. They again concluded that the dextrins produced by amylases are important in controlling the rate of bread firming.
A variety of gums can be used to increase the keeping quality of bakery products. When incorporated into a baked good formulation, 50gums have the ability to bind water into a gel to reduce water migration and to control rheological properties resulting in an extended shelf life. This extension of freshness can be ~ ' 2188893 attributed to the ability of gums to immobilize and bind water as well as interfere with hydrogen bonding between starch and protein i.e., the "bound" water exerts a plasticizing effect.
Examples of gums include guar, xanthan, locust bean gumr agar gum, cellulose, methylcellulose, alginates and pectins. As with other ingredients, they vary in their chemical structure and in their ability to bind water and to maintain freshness in a product.
~uar gum is a polysaccharide with a straight chain of D-mannopyranose units joined by linkages with a side branching unit of a single D-galactopyranose unit joined to every other mannose unit by a tl,6)linkages. It has a high hydration and water binding capacities, and forms a viscous colloidal solutions when hydrated in cold water systems.
Xanthan gum is a high molecular weight polysaccharide produced by the action of micro-organism on dextrose. It is very heat 20stable, it has a high moisture binding capacity and it contributes to the elasticity of the dough and shelf life extension of baked products.
Locust bean gum is a polysaccharide with a straight chain of D-mannopyranose units joined by ~ (l,4) linkages with a side branching to every fourth mannose by an ~l,6) linkage. It has very good moisture binding capacity and it is used extensively in frozen deserts, soft cheese and composite meat produGts.
30Agar gum is a complex polysaccharide mainly composed of agarose lwhich is the gelling agent) and another component which is very viscous and weak gelling. It is mainly used for its gelling and stabilizing properties.
Algin is a high molecular weight polymer of the salts of D-mannuronia and L-guluronic acids.
Pectin is a heteropolysaccharide which main component is the polygalacturonic acid partially esterified with methanol. Regular 40portions of pectin macromolecules ~oin to form so-called adhesion zones. The resulting formation of a three dimensional network permits the trapping of large amounts of water. (Fennema, 19~5).
Current theories on the staling process involves starch-protein interactions mainly through hydrogen bonding. Interference with this process through the use of enzymes or water binding ingredients such as HFCS can interfere with this hydrogen bonding. Since gluten is implicated in the staling process, another approach would be to replace high protein flour, either 50partially or completely with flour of lower protein content i.e.
lower gluten content to delay staling.

. ~

However, while the use of low protein flour (rice, corn and bar]ey) improved the textura] shelf life of the product ~Figure 2.15), the sensory shelf life of ~he product was of 3 days ~Table 2.17). In particular, bagel volume was low showing the importance of gluten for dough development and structure of the final product. Some studies have been done on the effect of different kinds of flours on bread firming. Boyacioglu and D' Appolonia (lg94) showed that the incorporation of 25'~. durum wheat flour resulted in a less firm crumb bread structure without lOaffecting any of the bread's characteristics. Torres et al.
(1993) showed that the addition of up to 20~, of sorghum flours, resulted in tortillas that were softer than the control without affecting their sensory qualities. These results disagree with our observations while the addition of. barley, corn or rice flours resulted in softer products, panelists rejected the bagels based on their characteristics.

-Table 2.17: Sensory resulls for rlce, barley and corn.
Sensory Analysis Flours Odor~2 Flavor Textur~ O~lerall Days of Storag~

Barley (25%)~ 3 ~ 3~4 ~ 3 2-9 -~ - 2-5 2.4 --~ 2.6 2 4 -- --~/_ 0.~ ~.5 -~ 0.2 --- --- ~. ---Corn (50%) 3 28 -- 2-8 28 -- -- 2-3 2.1 -- -- 2.3 21 -- ---Rice (25%) ~ 06 04 OM 05 0 o5 04 1 Based on a wheal ~lour .~pl~c;~"~en .
2 The sensoly was inlernJpled aner 14 days due l~ pa~ t:, request. the b~gels were mushy and sticky.
siy~ o~ wilh pcO.05, 0.005. 0.0005.
~~ ~nly for rlce.
Avera~e Or 5 replicales roll.wod (below) by ils Slandard D~vlallon.

The incorporation of surfactants into the formulation resulted in the following (results not shown). Atlas MDA (mono and diglyceride and ~amylase) at 0.25~ level gave a stale free shelf life of 25 to 35 days, according to sensorial and compressibility tests respectively. At the 0.375% level, it increased to 30 and 40 days respectively. However, the use of Atmul500 (mono and diglyceride, 2%), Atmul p28 (mono and. diglyceride, sodium stearoyl21actlylate and calcium sulfate, 0.375~) and Atlas SSL
50(0.375~ resulted in a shelf life of lO days according to sensorial tests and 25 days as shown by compressibility tests.
Thus, Atlas MDA appears to be more effective in delaying staling 218889~
~, probably due to the presence of enzyme in its formulation.
Furthermore, on comparlng the results by Atlas MDA and enzyme alolle, it was concluded that the additioII of mono and di~lyceride were not necessary to delay staling and that enzymes alone ~ould be used to extend the shelf life (Smith et al., l9g5, unpublished results). Previous studies with mono and diglyceride ~Maga, 1975) or with sodium stearoyl lactylate ~De Stephanis et aL, 1977) showed that surfactants bind to starch thus delaying retrogradation. However, Pisesookbunterng and D' Appolonia (19~3) 10observed that binding of surfactants to starch prevented the latter from absorbing moisture released from gluten. Thus this moisture migrated to the crust leading to crust staling and mold growth. A controversy also existed on whether surfactants affect the initial crumb firmness (Zobel, 1973) or the rate of firming (Ghiasi et al., 1982). Our results would indicate a slight decrease in the firming rate.
Humectants, such as high fructose corn syrup ~HFCS~ can provide shelf life extension by enhancing the water retention of baked 20goods. Thus, the retain moisture in the crumb resulting in a less firm, less stale fresher product. HFCS is a bright, transparent liquid. It is produced by treating high conversion corn syrup with immobilized glucose isomerase, an enzyme that catalyzes the rearrangement of the sugar molecule from the aldose to the cetose form.The transformation involves an intermolecular transfer of hydrogen between ad~acent carbon atoms to convert glucose to fructose. The high level of fructose gives its hygroscopic and sweet properties. Thus, it could affect staling by binding the moisture and/or by interfering with the hydrogen 30bond formation between protein and starch. However, at higher levels of use, it can cause stickiness and may adhere to packaging materials upon storage.

PACKAGlNG

Studies to date have focused on formulation changes to delay 40staling and enhance product shelf life. However, other factors such as storage atmosphere, storage temperature and method of production ~i.e., retarding or nonretarding) may also influence the texture of the product. Therefore, additional studies were done to determine if these storage processing factors had any effect in delaying staling in bagels.
Several studies have shown that gas packaging in a CO~ enriched atmosphere can be used to extend the mold free shelf life of baked products. Furthermore, some studies have shown that in 50addition to its antimycotic effect, CO2 may also have an antistaling effect, although results to date have been contradictory.

2~8~93 , ~

MAP is a new packaging technique. Various methods can be used to modify the gas atmosphere surrounding a product including gas packaging, the use of oxygen absorbents or ethanol vapor generation.
M~P has been mostly used to increase the shelf life of many food products including bakery products where they were found to extend the mold free shelf life of products. However, MAP may also have some effect delaying staling.
Under ambient storage conditions, baked products can develop visible: mold and firming within 48 hours of baking and packaging. The main types mold causing bread spoilage are Moniha sitophilla and members of Aspergillus, Rhizopus and Penicillium families. Four methods are effective retarding mold growth. These are modified atmosphere packaging ~MAP, irridiation, preservatives and freezing ~Black et al., 1993). Only MAP wi]l be discussed.
20Air is composed of ~78~ nitrogen ~N2), 21% oxygen ~~21 ~ and 1~
carbon dioxide (CO~). The principle of modified atmosphere packaging is that by changing the composition of the atmosphere around a food product,e. i., reducing the amount of O~ and increasing the levels of CO?, shelf life of food is significantly increased ~Doerry, 1985).
Young et at. ~1988) defined MAP as ~Ithe enclosure of food products in high gas barrier film in which the gaseous environment has been changed modified to slow respiration rates, 30reduce microbial growth and retard enzymatic spoilage with the intent of extending shelf life". It is estimated that the demand for MAP foods in North America could reach 11 billion packages the year 2000 ~Smith and Simpson, 1995).
Several methods can be used to modify the gas atmosphere surround bakery products. These include vacuum packaging (VP), gas packagIng, use of oxygen absorbents and ethanol vapor generators.
Some of the methods of atmosphere modification will be discussed.
40Vacuum packaging was the earliest form of MAP. VP is not used for most bakery products since this process causes irreversible deformation of soft products ~Parry, 19~3). E~owever, it is used to prevent rancidity problems in short bread (American Institute of Baking, Personal communication).
Gas packaging consists of replacing the air with a gas or a mixture of gases within the package, which is usually an impermeable film. Gases commonly used in MAP are carbon dioxide, nitrogen and carbon monoxide. Other gases, such as chlorine, 50ethylene oxide, nitrogen oxide, ozone, propylene oxide and sulfur dioxide have been investigated but are not used commercially. The most commonly used gases are N7 and CO2 alone or in combination 218889~
' ~"

with each other. The reason for this is that they are neither toxic, nor dangerous and they are not considered as food additives (Smith and Simpson, lg95).
N2 does not have a antimicrobial effect by itself since it is an inert gas. However, it is usually used as a filler gas to prevent the package collapsing in products that could absorb some CO~
upon storage. It is also used to prevent rancidity problems in food of low a i.e., where microbial spoi]age is not a problem.
CO? is the most important gas since it is both bacteriostatic, ~ungistatic and can prevent growth of insects in the package.
However, it is highly soluble in water and fats, and forms carbonic acid, resulting in flavor changes when used in high concentrations. Moreover, the product can also absorb CO~ causing the package to collapse.
The effect of CO~ can be summarized as follows:
201.The exclusion of O~ by replacement with CO~ may contribute to the overal antimicrobial effect by slowing the growth of aerobic spoilage microorganisms, 2.The CO2/HCO3~ ion has an observed effect on the permeability of cell membranes, 3.CO~ is able to produce a rapid acidification of the internal pH
of the microbialcellwith possible ramifications relating to metabolic activities, 4.CO~ appears to exert an effect on certain enzyme Systems ~Smith and Simpson, lg95).
In bakery products, the mold free shelf life increases with increasing concentrations of CO~ in the package headspace ~Smith and Simpson, 1995). Extensive studies have shown that CO~:N
~60:40~ mixture is most suitable and that this concentration is an effective one to increase the chemical and microbial shelf life of bakery products.
However, problems, such as staling and discoloration still occurs in some products. Also, if food is eaten directly from an MAP
pack, a bitter flavor of carbonic acid can noted. This usually appears in the product after four days of storage. The N~ gas also produces a noticeable offodor in bread within one day after baking, an odor which increases with time. The control (air atmosphere) produced a different ''stale" odor after seven days at room temperature (Brody, 1989). However, these odors could be overcome by toasting products prior to consumption (Smith and 50Simpson, l995) Q~ Q ~-~

l7 Oxygen absorbents are composed of any substances, packaged iIl gas permeable materials in the form of small pouches, which react chemically with oxygen. Placed in sealed packed containers, they reduce the oxygen concentration to 100 parts per million or even lower and maintain this level, as long as the appropriate packaging film is used. Substances commonly used are iron powder and ascorbic acid tSmith and Simpso~, lg95). The first oxygen absorbent was an iron powder based absorber developed by Mitsubishi Gas Chemical Company, under the trade name of Ageless 10in 1977. In 1989, almost 7000 million sachets were sold in Japan with sales of absorbents growing at a rate of 20~ per year (Smith and Simpson, 1995).
The absorbing reaction is the following:
Fe~Ee +2e 1/2 ~2 + H20 + 2 ~ 20H
Fe2+ ~ 20H ~ Fe(~H)2 Fe(OH)2 + 1/4 H20 ~ Fe(OH)3 (Brody, 1989).
ZOOther types of absorbents are now available on the market. These are Freshilizer and Freshpax absorbents all of which act in a similar manner to Ageless (Smith and Simpson, 1995).
Oxygen absorbers should meet specific criteria. These are:
l.The ingredients should not be toxic, 2.They should absorb oxygen at an appropriate rate, 3.There should not be any unfavorable side reactions, 4.They should be of uniform quality, 305.They must be compact and uniform in size (Brody, 1989).
Many factors influence the choice of oxygen absorbents such as:
l.The nature of the food, i.e., size, shape, weight, 2.The a of the food 3.The amount of dissolved oxygen in the food, 4.The desired shelf life of the product, 5.The initial level of oxygen in the package headspace, 6.The oxygen permeability of the packaging material (Smith and 40Simpson, 1995).
In Japan, oxygen absorbents are used extensively to prevent discoloration problems in pigmented products, and mold spoilage, especially in intermediate moisture and high moisture bakery products. Studies have shown that oxygen absorbents to be three times more effective than gas packaging for increasing the mold free shelf life of some bakery products. Five to fortyfive days for white bread at room temperature. fourteen days at 30 C for pizza crusts. In the United States, oxygen absorbents technology 50is still in its infancy.

. ~

Using oxygen absorbent technology, the she]f life o~ white pan bread could be increased 5 days to 45 days at ~oom temperature while pizza crust had a mold free shelf life of 14 days at 30 C.
The main problems with oxygen absorbents are consumer resistance to their use in food. Two main consumer concerns are the fear of ingesting the absorbent and the spillage of sachet contents into the food thus adulterating the product ~Smith and Simpson, 19951.
But on the other hand, oxygen absorbents are inexpensive, non-10toxic, fast and easy to use. They devolopment of rancid offflavors of fats and oils. Hence, the oxygen absorbent is a preservative free method for increasing shelf life and distribution by preventing mold growth.
Most of the studies to date with M~P have focused on extension of the mold free shelf life of products. However studies on the anti-staling effect of enriched CO~ atmospheres produced conflicting results. Doerry ~lg85~ observed that the crumb of bread became firmer irrespective of the storage atmosphere i.e., 20storage in air, 100% CO2 or 100~ N7. Brody ~19~9) reported that the staling rate of white and whole wheat bread was not significantly reduced when packaged in carbon dioxide or nitrogen as compared to air. Black et al. ~1993) also reported no clear pattern of firming over time between packaging treatments for pita bread packaged under various atmospheres.
However, Knorr et al. ~1985) showed that the compressibility of bread packed under CO2 was lower than bread packed in air suggesting that carbon dioxide delayed bread firming. Knorr 30~1957) reported that carbon dio~ide significantly decreased compressibility of some baked goods compared to air-stored samples and that softer products were obtained when stored under 100% CO~. While the initial compressibility of air and CO~ stored bread was identical bread stored in CO~ for 72 hours was significantly softer than the air-stored products ~Knorr, 1987).
Observed differences between water activity of the CO~ stored samples and air-stored samples after 96 hours of storage suggests that CO2 atmospheres may affect the water binding in bread ~Knorr, 1987).
Avital et al. (1990) reported that CO? delayed bread staling.
They proposed that changes in the sorption properties of MAP
baked goods were responsible for this effect. Since amylose is in the crystalline state after one day, amylopectin is the main component with available water binding sites. C07 appears to block some of these sites, thus causing a reduction in hydrogen bonding between the amylopectin branches resulting in a reduced water sorption capacity. Since hydrogen bonding has been shown to result in bread staling, blockage of water binding regions may 50explain bread finming. The effect of CO~ was found to exist when water was in "the solute state". The solubility o~ CO2 in water is 35 times higher than O~. Thus, it is possible that when water 218889~
~ ~, is in the solute stage, CO2 dissolved easily and bound strongly to amylopectin thus preventing hydrogen bonding, Smith (1994, unpublished results) also reported that the staling rate of white and whole wheat bread and biscuits was significantly reduced when packaged in 100~ CO2 compared to packaging in 100% N2 or air.

218~833 SU~MARY OP THF, II'~VF,I~lTlON
As aforesaid, the invention lies in the combination of the above mentionned techniques.Such combination has proved to be synergistic. The invention and its advantages will be better understood upon reading the following non-restrictive description made with referene to the according drawings FIG. 2.1. is a schematic representation of a standard bagel preparation.
FIG. 2.2 is a graphical representation of the compressibility of the control bagels at different days.
FIG. 2.3 is a graphical representation of the compressibility of bagels treated with Novamyl enzyme.
FIG.2.4 is a graphical representation of the compressibility of bagels treated with Superfresh enzyme.
FIG.2.5 is a graphical representation of the compressibility of bagels treated with Megafresh enzyme.
FIG.2.6 is a graphical representation of the compressibility of bagels treated with guar gum.
FIG. 2.7 is a graphical representation of the compressibility of bagels treated with xanthan gum.
FIG.2.8 is a graphical representation of the compressibility of bagels treated with locust bean gum.
FIG2.9 is a graphical representation of the compressibility of bagels treated with agar gum.
FIG.2.10 is a graphical representation of the compressibility of bagels treated with cellulose.
FIG.2.11 is a graphical representation of the compressibility of bagels treated with methyl cellulose FIG.2.12 is a graphical representation of the compressibility of bagels treated with algin gum.
FIG.2.13 is a graphical representation of the compressibility of bagels treated with pectin gum.
FIG2.14 is a graphical representation of the compressibility of 4C bagels treated with high fructose corn syrup.
FIG.2.15 is a graphical representation of the compressibility of bagels made of rice, barley and corn flours.
FIG.2.16 FIG2.14 is a graphical representation of the compressibility of bagels treated with surfactants.

~ '- 21~893 DET~IT Fn DESCRIPTION OF THE INVENTION

Bagels can be reformulated using appropriate levels of enzymes, gums, high fructose corn syrups and surfactants. Reformulation can be achieved using the standard recipe and baking procedure outlined in example 1. All ingredients were used at levels suggested in their commercial literature. The ingredients, and their levels of use, in the reformulated product are shown in lOTable 2.3 (page 5a ).
The textural and sensorial changes in non-reformulated (control) bagels were tested . The results are shown in Figure 2.2 and Table 2.4. All bagels had an initial compression test measurement of 0.008 MPa at day 0. This value increased steadily throughout storage to ~0.015 -0.016 MPa as a result of crumb hardening i.e.
staling. Based on these results, bagels were deemed stale when a compression test of 0.01 MPa was reached and this was used as the "staling standard" for all reformulated products. However, 20staling does not just involve moisture migration and crumb hardening but also a loss of flavor components. It is evident that all control bagels had an unacceptable odor, flavor, texture and overall desirability scores (<3) after 3 days. Therefore, while a 6 weeks mold free shelf life is possible using oxygen absorbent technology staling is still a major problem limiting the shelf life of bagels. This problem can be addressed through reformulation with enzymes, gums, high fructose corn syrups, flours of varying protein content and surfactants.

~ble 2.4: Sensory resulls for conlrol bagels.
Sensory Analysls Control OdorFlavor Texture Overaîl Days of Storage 4 ~ Control 2.2 2.2 1.8 1.6 2.8 2.ff 2.4 2.2 2.4 2.2 2.2 2 2.2 1.8 i.8 1.4 0.4 0.8 0.4 O.S 0.4 0.5 0.5 0.4 0.5 0.4 0.4 0.~ 1 0.4 0.8 0.5 A\~erage of S replicales IOIIJ~d (below) by lls Slandard Deviallon.

~0 21~9~

Thus, it appears that enzymes have a beneficial effect on crumb firmness, i.e., they delay the staling process. This can be attributed to the ability of these enzymes to "cut" the amylase and amylopectin branches of starch resulting in smaller branches which prevents starch-protein interaction. They also create low molecular weight sugars and dextrins improving the water retention capacity of the baked good. Furthermore, the three types of enzymes did not result in "stickiness" or "gumminess"
in the end product.
The results for the various levels of gums included in the reformulated bagel recipes and their effect on freshness are shown in Figures 2.6-2.13 and Tables 2.8-2.15.The effect of two levels of guar gum ~0.2 and 0.6~) on bagel softness is shown in Figure 2.6. Textural shelf life could be extended to ~20 days at the 0.2~ level ~flour weight basis) whereas at higher levels ~0.6~) bagels were stale after 30 days ~shown by compressibility test of 0.01 MPa). However, for sensory analysis of products only bagels formulated with 0.6~ guar gum were marginally acceptable 20after 28 days at ambient temperature.
The effect of three different types of cellulose (Type 40, 300 and 900) end methylcellulose, all used at the 1~ level ~flour weight basis) on the softness of bagels throughout storage are shown in Figures 2.10 and 2.11, and Table 2.12 and 2.13 respectively. The textural shelf life of bagels using cellulose 40 was terminated after 14 days. However, the shelf life could be extended to day 25 using cellulose 300 and 900 at the 1~
level ~Figure 2.10). Methylcellulose had an even greater effect 30On textural shelf life and bagels were still acceptable until day 30 using 1~ methylcellulose in the formulation. Furthermore, methylcellulose also had a more pronounced effect on the sensory qualities of the reformulated bagel as compared to cellulose ~Tables 2.12 and 2.13). With methylcellulose, products were still acceptable after 28 days at ambient temperature (Table 2.13).
Mold growth was visible in all air packaged bagels after 56 days at ambient storage temperature. However, by packaging bagels in either 100~ CO2 or with an Ageless type FX100 oxygen absorbent 40mold growth could be inhibited throughout the 42 day storage period. These results are in agreement of previous studies by Smith et al. (1996) and confirm the antimycotic effect of high C02 levels and low ~2 levels on mold growth. The antimycotic effect of various gas atmosphere on mold growth on bagels are shown in table 5.1.

;.1 s Elrecl Or ~ , c~ s~ e ~r l~ els F~r~tllllell~l Pllcî~ ly ~ Uny~ ~ vl~lble~
~ wll~
r.)~/0 ~07 N~
13~yeless ~X ~bs~rbQI1l NC~
C 1WSb C02 NG
ele~s l:X ~bs~belll NC~
E ~Ir ~-~
N(l- N~ uruwll~ r ~12 dnys.

21~g3 ~he results for textural and sensory changes throughout storage are summarized in Table 5.2. Shelf life in days was determined from graphical results when a compressibility of 0.01 MPa and a sensory score of <3 was reached (results not shown).

Inl~lc~.2lllre~t~rlr-cknhlllgc~ ns~ e.~ nln~ el~s~lnlsl~elr~ r ~n~cl~
~mlul0tl~l~ D~u~ll Pn~heg~ 8l~ellllrQ
l wlll~nu~pl)QrQt~xlure 8Qn~y ct:)2 b C02 ~14 ~14 B ~ I~gel~s ~X ~1'1 ~14 C 1Wo~o CC~ ~21 t~ - A~eles~ I~X ~Z8 -2 E~ Alr ~? c7 Air packaged bagels are stale in <7 days as observed previously.
Flushing bagels with 100% CO2 during mixing and subsequently packaging in 100% CO2 or with oxygen absorbents have little effect on either the textural or sensory shelf life. Indeed, bagels are staler than non flushed bagels packaged in either CO2 or with an oxygen absorbent (C and D).
Furthermore,bagels were rejected after 14 days due to an acidic sharp taste which can be attributed to either the CO2 in the 30dough or absorption of CO~ from the packaging atmosphere ~Formulation A). These results are contrary to the observations of knorr (1987) who reported that flushing enriched white bread dough under a CO2 atmosphere resulted in a softer bread. However, in these studies knorr (1987), flushed CO2 during the fermentation (proofing) stage and not during mixing as in our study. This latter route was taken as bagels formulated in our study had a limited proofing or fermentation time. However, our results agree with the observations of knorr and Tomlins (1985) who reported that French bread and white bread packaged under 40100% CO2 were significantly softer than air stored samples.
As shown in Figure 5.1. bagels packaged under 100~ C~2 have a compressibility of 0.009 after 42 days at room temperature i.e., within the "staling standard" of 0.01 MPa. However, while textural shelf life is acceptable, bagels are rejected after 21 days again due to sharp acidic taste probably caused in dissolution of headspace CO2 in the aqueous phase of the product.Finally, bagels packaged with an oxygen absorbent (Formulation D) had a textural and sensory shelf life of 28 days.
In conclusion, the results confirm that flushing CO2 into the dough during the mixing stage does not have a beneficial effect ~1~$~ 3 ' ~, on crumb texture i.e., staling. It has also shown that packaging bagels in 100~ CO2 could be a useful alternative to reformulation to delay staling. While the exact antistaling mechanism of CO2 is not known, it may affect the hydrogen capacity of proteins which would have a plasticizing effect on starch-protein interactions.
Hence, bagels reformulated with enzymes, gums and HFCS in combination with modified atmosphere packaging ( e.g. elevated levels of CO2) have an anti-staling effect for 42 days and are lOedible within 21 days after packaging.

2 1~ 3 ~, E~ PLEl (reformulation) Bagels were reformulated with the ingredients mentioned hereinabove in "reformulation" so as to monitor their effect on the textural and sensorial qualities of baggels over a 6 weeks period at ambient storage temperature ~25 C).
All ingredients were added to a Hobart mixer ~D300, Hobart 10Canad~Inc., Don Mills, Ontario~ and mixed at a high speed, for ~10 mins until the dough was formed and then at low speed for 5 mins until the dough was properly developed i.e., indicated by dough temperature (30 C~ and by the feel of the dough. The dough was then removed from the mixer, kneaded, and proofed at room temperature for ~10 minutes. After proofing, the dough was cut into 75g pieces and shaped manually into a bagel form. The bagels were then proofed for an additional 5 minutes prior to being boiled in a kettle filled with boiling water containing honey (4 tablespoons in lOL water) until they floated to the surface.
20Bagels were then removed from the kettle using a wire sieve and drained of excess water. The bagels were coated with sesame seeds or both sides, placed on wire racks and baked for ~18 minutes ~g minutes on each side) in a convection oven at 400 F (Garland Convection Oven (TE3,4CH Commercial Ranges Ltd., Mississauga, Ontario).
After baking, bagels were cooled to room temperature and packaged (2 per bag) in Cryovac barrier bags (size 210x210 mm, Cryovac, Mississauga, Ontario, Canada). An Ageless type FX100 oxygen 30absorbent ~Mitsubishi Gas Chemical Co., Tokyo, Japan) was added to each bag to prevent mold growth during storage. All packaged bagels were stored at 25 C for 6 weeks, and monitored for textural and sensorial qualities at regular intervals (days 0, 3, 7, 14, 28 and 42). A flow process of bagel preparation is shown in Figure 2.1.
Based on this initial study, the estimated shelf life of bagels for all reformulated products stored at 25 C are shown in Table 2.18. The textural shelf life was based on the time (days) to 40reach a compressibility of 0.01 MPa. While sensory shelf life was based on time (days) to reach an overall acceptability score of ~3. It is evident from these results that certain ingredients may result in a desired textural shelf life of 42 days, yet have a lower sensory shelf life, and vice versa.
However, certain formulation involving enzymes (Superfresh, and Megafresh at the 0.150.2% level) resulted in a 42 day extension in textural and sensorial shelf life of bagels. Algin gum at the 0.2~ level also produced similar extensions in shelf fife. While 50HFCS at the 50% level delayed staling for 42 days, sensory shelf life was regarded unacceptable after 28 days. Pectin also gave a favorable extension in both textural and sensory shelf life.

~ 2t8~893 F.X~IPI F.~ (reformulation) Novamyl is a genetically modified maltogenic amylase produced by a genetically modified strain of Bacillus subtilis (host) which has received the gene for maltogenic amylase from a strain of Bacillus stearothermophilus. When used at a level of 0.031%
lO(flour weight basis~ it had a pronounced effect on the textural shelf life of bagels (Figure 2.3). At the end of the 6 week storage period, bagel texture had changed very little (from 0.006 MPa to 0.007 MPa~ over this time period. This was well below the textural standard of O.Ol MPa used as an indicator for staling.
However, higher levels ~0.047~i) did not result in an improved textural shelf life. Indeed, product was regarded as stale after ~14 days as indicated by a compressibility test of O.Ol MPa (Figure 2.3).
20The results for the sensory scores of bagels reformulated with Novamyl are shown in Table 2.5. Based on a "cut-offl acceptability score of 3, it is evident that bagels reformulated with 0.031% Novamyl, had a sensory shelf life-of 28 days which is interesting. Thus, while objective measurements resulted in a shelf life of ~42 days, product had a stale flavor and odor after 28 days and was considered "stale" by panelists.

Table 2.5: Sensoly results for Nov~myl enzyme.
Sensory Analysis Novamyl Odor Flavor Texture Overall Days of Storage 0 031% 3.63.73.83.53.83.83.82.23.83.73.~ 2.73.83.73.72.n +/_ 0.91.20.70.8100.70.910.50.71.50.~ 0.50.81.1 o 047% 3.~ 3.43.73.43.23.23.23.53.12.92.52.5 ~.43.63.73.3 ~/_ O.B 0.81110.71.1 ~.8110.81.210.510.8 The compressibility results were highly significant with a p-value of <0.0005 (normally a p-value of <0.05 is considered significant). However, the sensory results were not significant and this is mainly due to the nature of the sensory analysis and the difficulty of the judging task. The p-value measures the relation between the variables and the outcome. When the p-value is 0.05,the results are considered statistically significant, i.e., indicating that the results are not due to chance, but 50there is a real relation between the days of storage, the level used and compressibility outcome. Furthermore, as expected less than 2596 correlation was observed between compressibility and the 21~1 9 3 2~
sensory results, showing once more that even if texture is an important cause of sample rejection, flavor and odor still influence panelistls perception of freshness.
.

EX~PLE3 (refonmulation) Similar trends were observed for bagels reformulated with lOSuperfresh and Megafresh enzymes.Superfresh is a mixture of fungal and bacterial amylases which act by hydrolyzing the (l,4) glycosidic linkages of starch by hydrolyzing maltose units into simple sugars. Its effect on the textural and sensorial shelf life of bagels at levels ranging from O.l to 0.2~ ~flour weight basis~ are shown in Figure 24 and Table 2.6. At lower levels of use (0.1%) firmness was fairly constant over the storage period.
At higher usage levels (0.15-0.2%), firmness measurements increased slightly from an initial level of 0.006 MPa but were well below the "staling standard" of O.Ol MPa after 42 days.
20Sensory results showed that optimum results could be achieved with 0.15 or 0.2% Superfresh in the formulation ~Table 2.6), i.e.
a textural and sensorial shelf life of 6 weeks was possible using this level of enzyme in the reformulated product.

Table 2.6: Sensory results for Sl,perr.~sl~ enzyme.
Sensory Analysis Sup~.rl~,sh Odor Flavor Texture Overall Days of Storage 01% 3.93.73.63.43.~ 3.73 2.63.43 3.22.63.93.53.22.~1 +/_ 0.60.41.10.50.50.41.50.81 0.81.31.10.60.51.30.8 0.15% 3.23 3.23.64 2.62.62.84 3.23.23.83.93.23.63.4 +/_ 0.40.70.80.80.30.81.11.50.60.81 1.30.50.41.11.3 0 2% 3.63.63.63.43.73.63.63.23.43.23 3.23.63.43.23.4 +/_ 0.91.11.10.51 1.11.11.31.10.81 1 1 1.10.80.5 Averaqe of s ,.~I'cqtes ~ n,~d (below) bv lls Slandard Devialioll.

Superfresh followed the same trend as Novamyl i.e., the compressibility results were highly significant with a p-value ~0.0005, while the sensory results were not significant. The correlation between the compressibility and the sensory was 50also less than 25%.

2~18~ 8 9 3 F.X~MPI F 4 (refornwlation) The effect of Megafresh, a bacterial a-amylase and glucotransferase enzyme system on staling are shown in Figure 2.5 and Table 2.7. At the lower level of use ~0.1~) bagels had a compressibility measurements of 0.006 MPa after 42 days. At the 100.1596 level, results were similar to those obtained with 0.159~
Superfresh and 0.031% Novamyl i.e., products became slightly firmer throughout the 42 days storage period. At the higher level of use (0.2%) bagels reformulated with Megafresh reach their max;mllm firmness after 35 days ~Figure 2.5). Sensory analysis showed that optimum results were obtained using 0.159~ Megafresh i.e., a textural and sensorial shelf life of 6 weeks was possible using this level of enzyme in the reformulated product (Table 2.7).
--. Table 2.7: Sensory resulls for M~ar,esl, enzyme.
- Sensory Analysis MegafreshOdor Flavor Texture Overall Days of St~rage 7 14 28 427 14 28 42 7 .14 28 42 714 28 42 01% 3.63.63.6 --'3.33 3 - 3.53.43.2 --3.43 3 --+/1 0.5 ~).8 ---1.41 0.7 --- 1.10.51 -1.30.70.~ ---0.15% 3.73.E~ 3.83.63.93.43.43 4 3.43.43.43.~ 3.43.43.4 ~/_ 0.60.80.~ 0.50.~11.10.50.71.10.50.50.80.70.50.50.5 0 2% 3.43.43.4 ~ 2.82.82.8 2.82.82.8 - 3 3 2.8 --+/_ 0.70.51.1 - 0.70.81.4 --- 0.90.81.3 --- 0.80.70.8 ---1. The sensory was inlerrupled due to mold growth.
Averaye of 5 ~-."c les ~ollowed (below) by ils Slandard Dcvialion.

Compressibility results were again highly significant with a p-value however the sensory results were also significant with a p-value ~0.005. However, here again, statistically, no correlation was found between the compressibility and sensory 50results.

21~1~893 E~ PLE5 (refonmulation) Compressibility and sensory analysis test results for three levels of xanthan gum 10.2, 0.6 and 1%) are shown in Figure 2.7 and Table 2.9.
Table 2.9: Sensory results for xanthan gum.
Sensory Analysis 1 0 Xanthan Odor~ Flavor* Texture*~ Overall~
Days of Storage 02% 3.73.8333.43.232.53.132.82.63.232.62.4 ~/_ 0.90.41.31.30.70.71.511.311.61.30.80.61.21 06% 3.532.82.22.72.62.422.82.621.62.62.~ 2.82 +/_ 0.80.70.80.811.31.611.40.80.70.81.40.80.80.7 2.52.52.52.62.521.621.71.51.61.62.2222.2 +/_ 0.81.211.210.80.50.81.20.70.50.80.410.90.8 Texturally, products were rejected after day 12 at lower and upper levels of xanthan gum i.e., 0.2 and 1~ ~Figure 2.7 ).
However, at the 0.6~ level, bagels had a textural shelf life of ~25 days. Sensorially, however, products were rejected after 7-14 days for all levels of xanthan gum used. Favorable compressibility results were observed for bagels reformulated with locust bean gum (Figure 2.8) with the best results being obtained at the 0.6% level of use ~Figure 2.8). However, with the 30exception of odor scores, products containing locust bean gums, were rejected by panelists after 7 days of storage as shown by the sensory results in Table 2.10.

Table 2.10: Sensory results for locust bean gum.
Sensory Analysis Locust bean Odor~ Flavor Texture Overall Days of Storage 02% 2.63 ~ 2.42.2 - - 2.22 - - --- 2.42.2 - - ---+/_ 0.80.8 - - - - 0.50.9 ~ - - 0.80.8 - - - - 0.50.9 --- ~
0 6% 3.53.73.7 --- 2.72.73 --- 2.52.72.2 -- 3.12.72.6 ---0.50.50.8 - 0.90.51.5 --- 1.21.20.4 ~ 0.61.20.8 --33.23.5 -- 333 ~- 2.72.52.8 --- 2.42.72.8 ---~/_ 0.70.50.8 - - 0.801.2 ~ 0.~ o.s o.g - - O.S 0.50.9 1. The sensory was interrupted due to mold growth.
si~ll'fica..l with p~0.05, 0.005, 0.0005.
Averaue Or 5, . pl.' ~ dlcs followed (below) by its Standard Dcviallon.

21~'8g3 rXA~LE6 (reformulation) A similar trend in textural and sensorial shelf life was observed for bagels re~ormulated with agar gum (Figure 2.9 and Table 2.11). Thus, while gums appeared to inhibit staling due to their water binding capacity they fail to enhance the organoleptic quality of bagels as shown by the low sensory evaluation scores.
These results confirm the controversy effect of gums to decrease bread firmness (Maga, 1975, Mettler and Seibel, 1993) while lOothers found that gums had no effect on firmness (Christianson and Gardner, 1974).
Table 2.11: Sensory resulls lor agar ~um.
Sensory Analysis Agar Odor~Fîavor*~ Texture~ Overall~
Days of Storage 0.2% 3.7 3.5 3 --' 3.5 3 2.8 -- 3.5 3.2 3 -- 3.3 3 2.4 --2 0 +/- 0.5 0.5 0 ~ 0.8 0.6 0.4 -- 0.8 0.7 0.7 0.5 0.~ 0.5 06% 2.~ 2.8 2.~ 3.3 2.3 2.2 -- 3.1 1.8 1.5 -- 3.4 2.2 2.1 +/_ 0.7 0.4 0.4 -- 1.1 0.8 0.7 --- 1 1.1 0.5 --- 0.9 0.4 0.4 % 3.7 3.5 3,2 --- 3 2.9 2.a - 2.8 2.7 2.6 -- 3 2.S 2.~ --+/_ 0 5 ~ S 0 4 -- 1 0.~ 0.4 -- 1 .4 0.8 0.8 -- 0.~ 0.4 0 4 1 The sensory was interrupled due lo mold growlh.
si~ "lc~lll ~th p~O.05, 0.005, 0.0005.
Avern~e o~ S ~~ rl_s r~llJ~vc~ (below) by its Standard Devlation.
30~XA~PT.F. 7 (reformulation) Both algin and pectin ggums also gave ~avorable results from a textural viewpoint, particularly at the lower levels of use i.e., 0.2 and 0.6~ (Figure 2.1 and 2.13). However, as with other gums, sensory shelf life was always less than the textural one as shown in Tables 2.14 and 2.15. Thus, while gums have a beneficial effect on staling, its effect varies from gum to gum. This is expected since the chemical structure of each gum is different and hence the water binding capacity and plasticizing effect will 40vary. However, it is evident that gums appear to have a greater effect on the textural quality of bagels compared to their sensory effect as shown by the consistently lower sensory scores for bagels reformulated with gums.
Statistically, most gums followed the same pattern. The~
compressibility results were highly significant with p-values of less than 0.005 to 0.0005, while the sensory results were not significant with p-value of less than 0.5. However for agar and xanthan gums, the compressibility results were not significant 50values of 0.5 (xanthan) or less (agar), while their sensory results were significant with p-values of 0.0005 (agar~ and 0.005 (xanthan). Very low correlations were found between 218~893 ~_ 3~

compressibility and sensory results in most of the gums studied.
However, correlations > 5096 were observed for agar, guar and locust bean gums. This again shows that when the texture, measured objectively, is "acceptablen, other subjective attributes such as flavor and odor influence shelf life.
.

Table 2.14: Sensory resulls for algin gum.
Sensory Analysis Algin Odor Flavor Texture Overall Days of Storage 02% 3.5 3.6 4 4 3.5 3.2 3.43 2.7 2.6 2.72.6 3 - 3.2 3.2 3 ~/ o.s 0.s 1 0.6 0.5 1 0.80.61.5 0.8 0.7 0.4 1.1 0.8 0.8 0.7 06% 3.s 2.7 4.2 4 2.7 2.2 3.43 3.2 2 3.4 3.2 3 3.s 3.6 3.4 +/ 0.s o.s o.s 0.60.s o.s 1.10.60.s o.s 0.s o.40.s 0.s 0.s 0.4 1 % 3.2 3.4 3.8 3.53.7 3.8 3.43 3.7 3.8 3.4 3 3.s 3 3 2.9 +/ 0.5 0.8 0.9 0.50.5 1 1 0.60.2 0.7 0.6 0 0.8 1.1 1.1 0.4 Average of 5 r.,' ~ ~'es ~ollowed (below) by its Slandard Dcv;alion.

Table 2.16: Sensory results ~or pèctln ~um.
Sensory Analysis Pectin Odor Flavor~ Texture Overall Days of St~r~e 02% 3.33.3 3.73.53.6 3.5 3.3 3 3.4 3 2.7 2.73.4 3.2 2.9 2.7 +/ 0.41.2 0.5 0.80.5 0.8 0.5 0 0.2 0.8 0.5 0.70.9 0.g 0.4 0.8 06% 3.13.8 3.7 3.42.7 4 3.3 3 3 3.3 3 2.73.s 3.s 3.2 2.9 ~/ 1 0.7 0.5 0.40.4 0.6 0.8 0 1 1 1.2 0.6 0.6 1 1.1 0.4 1 % . 3.43.s 3.s 3.23.63.72.82.s 3.s 332.s 2.s 3.6 3.7 3.22.9 +/ 0.90.7 0.5 0.40.71 0.70.s 0.30.s 0.70.s 0.71 0.7 0.4 nirica"l wilh p~0.05,0.005, .0005.
Avera~e of S l~r~ les followed Sbelow) by its Slandard Dcv;alion.

.
.

.

E~ PLE8 (reformulation) The effect of HFCS (liquid or granular) as sugar replacement in the bagel formulation is shown in Figure 2.14 and Table 2.16.
Both granular and liquid HFCS had a significant effect on crumb staling as shown by compressibility tests (Figure 2.14).
After 42 days, products refonmulated with liquid HFCS (50%) were almost as fresh as day 1 bagels while bagels containing granular lOHFCS ~100%) were only slightly firmer than day 1 bagels. However, while higher levels also delayed firming, products were very sweet and sticky due to the hygroscopic nature of HFCS. From a sensory view point, only the 50~ liquid HFCS gave acceptable scores with sensory shelf life being acceptable at the end of the 42 days storage period. Thus, HFCS at this level has the potential to delay staling and to produce an organoleptically acceptable product. High fructose corn syrups compressibility results were highly significant with p-values of 0.0005, while the sensory results were not significant, i.e., similar results 20to enzymes and gums.

Table 2.16: Sensory results for hlgh fruclose corn syrup.
Sensory Anaîysis High r~ 5Q Odor Fîavor~ Texture Overaîl corn syrup Days of Storage Liquid 5o%1 3-536353 2.83.63.43 3 343 3 2.53.23 3 +/_ 0.~10.50.70.70.50.50.50 0.80.82 0.72 0.80.71 Liquid 100% 3.53.53.23 3.33.53 2.53.83.23 2.53.53.23 2.6 +/_ 1 1.21 0.50.91.51.51.40.51.51.20.70.71.51.10.7 Granular 50% 373 2;8263-7262-42 2.72.62 2 3 2.62.42 +/_ 1 1.21 0.50.91.51.51.40.51.51.20.70.71.51.41.7 Granular100% 3 333 2-5322-82-4.2 2.62.52.22 3.23 2.62 +/_ 1.10.50.70.50.90.80.80.71.20.50.80.71.20.80.51 1. Based on a sugar leplace.,.enl basis.
The producls wilh high fruclose corn syrup were sweeler and slickier Ihan lhe ones using sugar siy~ ic6lll wilh pc0.05l 0.005, 0.0005.
Average of 5 I~p'ica'cs lo'l.J/cd (below) by ils Slandard Dcvialioll.

~, EX~PLE9 (Combined) This present essay is to confirm the antimycotic effect of CO2 and to determine its effect on staling.
A standard bagel recipe, as outlined in example 1, was used through this study. To determine the effect of CO2 on shelf life, 104 processing packaging conditions were investigated. These were:
A. Flushing dough with CO2 during mixing packaging in 100% CO2;
B. Flushing dough with CO2 during mixing packaging with an Ageless FX 100 oxygen absorbent;
C. Packaging baked bagels in 100~ CO2;
D.Packaging bagels with an Ageless FX oxygen absorbent; and E.Packaging bagels in air.
In A and B, CO2 was flushed directly into the dough in the Hobart 20mixer for 10 mins until dough was properly developed. The dough was then proofed at room temperature for 10 mins, cut in 75g portions, formed, boiled, dipped in sesame seeds and baked as described in example 1.
In C, D and E, bagels were mixed, proofed, cut, formed, boiled, dipped in sesame seeds and baked as described in example 1.
All bagels were packaged in 20x20 cm Cryovac bags (2 per bags).
Formulations A and C were packagedi sealed with 100% CO2 in a 30Multivac chamber type heat seal packaging machine (Model 4300/4s, Multivac Wolfertachwenden, Germany). A Smith proportional gas mixer, model 299028 (Tescom Corporation, Minneapolis, Minnesota 55441, USA), was used to give the desired proportion of CO2 in the package headspace. Gases (CO2 and N2) were obtained from Medigas Ltd (Quebec, Canada). Formulations B and D were packaged with an Ageless FXlO0 oxygen absorbent taped inside the bag. All packages were sealed manually using an impulse heat sealer.
Control bagels (E) were packaged in air as described above.
40All packaged bagels were stored at 25 C and monitored for visible signs of mold growth. Textural and sensory analysis were done at day 0, 7, 14, 28 and 42. The results ~or textural and sensory changes throughout storage are summarized in table 5.2. The antimycotic effect of various gas atmosphere on mold growth on bagels are shown in table 5.1.

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