QUALITY ASSURANCE TRAINING

compiled by: R.Babu John

TOPICS

Hygiene

Introduction to General Microbiology

Microbiology of High-Acid Food

Microbiology of Low-Acid Food

Aseptic Technology

Aseptic Packaging

Cleaning in Place

Common Defects observed in UHT Products

Hygiene
Importance of staff Hygiene and factory Hygiene

Food Hygiene

Staff Hygiene

Plant & Production Hygiene

Source of Contamination

FOOD HYGIENE
Safeguarding a defect free raw production.

Investigating the reasons that leads to a hazard or will have an impact on quality

Measures to control food hygiene during recovery, production, treatment, storage,

transport, Distribution
STAFF HYGIENE
Interference in the aseptic zone

Working clothes, head covers,

Infectious disease

Open wounds

PLANT&PRODUCTION HYGIENE
Sanitary requirements of

Machinery and working tools and equipment.

Cleaning the machine after each production

CIP of the machine

Source of Contamination

Bacteria may be introduced into food directly from the person e.g. :

From the Hands & Skin, Coughing/Sneezing

From the Intestine

From Boils, Cuts, Spots,

From Clothing,

From Jewellery,

From Hair,

When must you wash your hands ?

After Eating, Smoking, Touching Face,

After the Toilet,

Entry to Food Rooms

After Touching Waste between Raw &

 Cooked

After Sneezing, Coughing

After Cleaning

Introduction to General Microbiology

Definitions

Classification of Microorganisms – Bacteria

Classification of Microorganisms – Yeast & Moulds

Classification of Microorganisms – Algae and Protozoa

Classification of Microorganisms – Viruses

Definitions
Aseptic: The absence or exclusion of any unwanted organisms from the product, package, or other
specific areas. 

Aseptic zone: Aseptic zone is the area inside the Combibloc-filling machine, in which the actual aseptic
filling is affected. The area starts at the station, where the cartons sealed at the bottom are sterilized
and ends with the sealing of the cartons. Before the start of the production, this area is sterilized by
H2O2 sterilization of the aseptic zone. During production, this area is kept germ free by blowing in air
passed through a sterile air filter and by way of maintaining a “Laminar flow” condition.

Laminar Flow: The aseptic zone inside the Combibloc-filling machine is kept sterile during production by
having a continuous flow of germ-free air from the top towards the bottom of the chambers. The
intended condition is so called “laminar flow”. Germ free air flows uniformly into one direction
preventing any kind of swirling effect resulting in a swirling up of germs from area underneath the filling
machine into the aseptic zone. Perforated plates installed in the upper section of the aseptic zone
uniformly distribute the sterile air fed in. 

Pathogens: Disease causing bacteria.

Microorganisms: Organisms that are visible only through a microscope. They include yeasts, moulds and
bacteria.

Bacteria: Microorganisms that exist throughout the world. Single celled organisms of various shapes
that are visible only through a microscope. Most are harmless and even useful to humans, but a small
proportion are dangerous, causing food poisoning and other food borne illness. 
Food poisoning: An acute illness caused by the consumption of food contaminated by bacteria, other
microbes, such as viruses, or physical or chemical contaminants. The symptoms are characterized by
abdominal pain, with or without diarrhea and vomiting. 

Toxin: A poison produced by bacteria.

Contamination: The transference of any objectionable or harmful substance or material to food.

Contamination may be microbial, physical or chemical and may occur directly, indirectly or by cross
contamination

Blown: A pack that bulges because of the formation of the gas inside due to microbial fermentation. 

Enzyme: A chemical produced by cells that break down proteins, fats, sugars and other substances. 

Aerobic: Microorganisms require oxygen to multiply. Some can grow only if there is available oxygen. 

Anaerobic: Microorganisms require no oxygen to multiply. Some can grow only if oxygen is absent. 

aw Water Activity: The water available to microorganisms.

Spoilage: The decomposition of food by bacteria, moulds, enzymes or chemical interactions.

Spore: Some types of bacteria have the ability to form spores. They are like growths inside the normal
(or vegetative) cell. They develop to survive adverse conditions involving heat, chemicals, starvation or
other threats. Although the original bacterium may die, the spore survives and forms another bacterium
when favorable conditions return. 

Sterilization: Heat treatment that destroys all most all living microorganisms. 

UHT treatment

UHT is the abbreviation for Ultra High Temperature. UHT treatment is a technique for preserving liquid
food products by

exposing them to brief, intense heating, normally to temperatures in the range of 135 – 140°C. This kills
micro-organisms

which would otherwise destroy the products. UHT treatment is a continuous process which takes place
in a closed

system that prevents the product from being contaminated by airborne micro-organisms. The product
passes through

heating and cooling stages in quick succession. Aseptic filling, to avoid reinfection of the product, is an
integral part of the
process.

Virus: Extremely small pathogens, visible only through an electron microscope, that multiplies in the
living cells of a

host such as humans. 

Fungus: Single-celled microorganisms including mushrooms, moulds and yeasts.  

Yeast: A single celled fungus, which reproduces by budding and grows rapidly on certain foods,
especially those

containing sugar. 

Mould: Various types of microscopic fungus that may appear as woolly patches on food. 

Hazard: Any thing that could cause harm. Food hazards include contamination by microorganisms,
chemical and

physical objects. 

Hazard analysis: A system to help ensure that food business produce, process, store and sell food that is
safe to eat. 

Critical control point (CCP): A point in a stage of food handling identified in the HACCP system of hazard
at which

control can eliminate a hazard (or reduce it to safe level. Not all points are critical. Those, which are
critical, are

essential for ensuring the safety of the food.  

Classification of Microorganisms
Bacteria

Yeasts

Moulds fungi

Algae

Protozoa

Viruses
Shape of Microorganisms
Rods and Cocci

Growth factors
Temperature, Water activity, Humidity,

Oxygen, pH, Light, Inhibitors, salt etc.

Classification of Microorganisms Bacteria

Three Major Groups

Pathogens:

may cause disease in human beings or produce toxins

Eg: Staphylococcus aureus Vomiting, Diarrhea (Produces exotoxins Source: Human skin, nose, hands,
throat, hair)

Escherichia coli: diarrhea (produces verocytotoxin Source: Human and animal intestine, indicator of poor
personal hygiene.

Spore formers:

Very resistant form against both physical and chemical means of elimination. Difficult to kill. Limited
number of bacteria form spores, Most important in the production of low acid sterilized foods. They are
in resting forms, They don’t multiply. Under right conditions one spore may germinate into one
vegetative bacterial cell.

Vegetative cells:

Growing or multiplying state of bacteria, bacterial multiplication consists of splitting one cell to two cells,
Generation time is the time necessary for one cell to become two and GT is faster under favorable
conditions (Temperature, Nutrients, Moisture contents, Oxygen availability, pH) GT for E. Coli is 10-
12minutes

Classification of Microorganisms-Yeast & Moulds

YEASTS:Yeast are single-cell organisms of spherical, elliptical or cylindrical shape. Usually form oval cells
with a diameter of about 2-8µ and length of 3-15µ.

Condition of the growth of yeast

Nutrients: Yeast has a same need for the nutrition as other living organisms.

Moisture: Like bacteria, yeast must have access of water to be able to live, but yeast needs less water
than bacteria. Growth in jam and honey shows that they can withstand strong osmotic pressure.
Acidity: Yeast can grow in media with pH values ranging from 3-7.5. The optimum pH is usually 4.5-5.0

Temperature: Yeast can grow at temperatures below the freezing point of water or above about 47°C.
The optimum temp is between 20°C-30°C.

Growing cells are normally killed within 5 to 10 minutes at temperatures of 52°C to 58°C.

MOULDS:

External Factors affecting the growth of Moulds:

Moisture: Moulds can grow on a materials with a very low water content and can extract water from
moist air.

Water activity(aw): Moulds are more lolerant to low aw than bacteria.

Acidity: form typical structures of growth & multiply at wide range of pH from 3 to 8.5.

Oxygen: Oxygen is needed, normally grow in aerobic conditions.

Are used for manufacturing some cheese varieties

Certain species produce toxins which accumulate in the human body cause cancer.

It makes juices cloudy, turbid, Slimy.

Algae:

Algae range from single-celled organisms to multi-cellular organisms, Algae have been traditionally
regarded as simple plants, and indeed some are closely related to the higher plants.

Protozoa:

Protozoa (in Greek proto = first and Zoë = animal) are single-celled eukaryotes (organisms whose cells
have nuclei) that show some characteristics usually associated with animals Most protozoans are too
small to be seen with the naked eye - most are around 0.01-0.05 mm, although forms up to 0.5 mm are
still fairly common - but can easily be found under a microscope.

A virus (Latin, poison) is a submicroscopic particle that can infect the cells of a biological organism. At
the most basic level viruses consist of et genetic material contained within a protective protein shell,
which distinguishes them from other virus-like particles such as prions and viroids. The study of viruses
is known as virology, and those who study viruses are called virologists.
Viruses are not plants, animals, or bacteria, but they are the quintessential parasites of the living
kingdoms. Although they may seem like living organisms because of their prodigious reproductive
abilities, viruses are not living organisms in the strict sense of the word.

Classification of Foods
Food generally classified in two groups based on pH.
Those food with pH below 4.5 is high acid food (Juices, Nectar, Tomato products etc.)
Those food with pH above 4.5 is low acid food (Milk, Cream, fish etc.)
The Micro flora of the food is changed according to pH and that decides the heat treatment given for the
preservation

Microbiology of High-Acid Food

Al though several micro-organisms have been isolated from orange juice, few of them cause spoilage.
The high acid (low pH) of juice limits the types of microorganisms that can grow in the juice. Juice
spoilage is caused by micro-organisms which are able to multiply in juice during its processing and
storage.

Acid-tolerant bacteria

Yeasts

Moulds

The growth of micro-organisms in orange juice is characterized by fermentation and/or the production
of off-flavour which spoil

the product. Fermentation may lead to gas formation, which, in turn, results in blown packages.

ACID-TOLERANT BACTERIA

Lactic acid bacteria are the most common acid-tolerant bacteria which cause spoilage of orange juice

YEAST

Yeast are the most common type of spoilage organism in both single-strength and concentrated orange
juice. Spoilage of orange juice by yeasts typically results from an alcoholic fermentation which leads to
off-flavors and CO2 production. Yeasts not capable of alcoholic fermentation may cause turbidity,
flocculation and clumping in juice.

The optimal growth temperature for the most yeasts are 20º-30º C. They are most tolerant of cold
temperature, high osmotic pressure and lack of nutrients than bacteria or moulds.
MOULDS

Moulds from colonies of aerial mycelia on the surface of juice, and flocculation of floating

mycelia within juice. They can grow under a wide variety of conditions. In general, moulds

grow well in acid media and require abundant oxygen. Moulds that grow in orange juice are

generally sensitive to heat treatment and are thus easily destroyed by pasteurization.

Compared with yeasts and bacteria, moulds have only infrequently been associated with

spoilage of orange juice. This is because of their aerobic (oxygen dependent) nature and slow

growth rates.

PATHOGENIC MICRO-ORGANISMS

The presence of pathogenic microorganisms in orange juice is rare. The low pH of juice inhibits growth
of pathogens, but long term survival of some pathogens in refrigerated orange juice is possible.
Consumption of unpasteurized orange juice or contaminated reconstituted juice before serving may
lead to outbreak of disease, particularly Salmonellosis.

Diseases attributed to orange juice are mainly caused by incorrect product handling and can be
prevented by carrying out approved sanitary procedures, pasteurizing the juice, and by preventing
product contamination after pasteurization.

SPORE-FORMING MICROORGANISMS

Most spore forming bacteria can not grow in fruit juices with a pH below 4.5. Though very rare,
thermoresistant acidophilic bacteria have been isolated from shelf-stable juice.

Microbiology of Low-Acid Food

Bacteria in Milk

Due to its very specific composition, milk is susceptible to contamination by a wide variety of bacteria.

Daily cleaning and disinfection of all milking equipment is therefore the most decisive factor in the
bacteriological quality of milk. For milk to be classed as top quality, the bacteria count, the CFU (Colony
Forming Unit), should be less than 100 000 per ml.

Principal Bacteria in Milk

Lactic acid bacteria

Lactic acid bacteria are found on plants in nature, but some species occur in particularly large numbers
in places where there is milk. The group includes both bacilli and cocci, which can form chains of varying
length but which never form spores.

Most of the bacteria are killed by heating to 70ºC, though the lethal temperature for some is as high as
80ºC.

Lactic acid bacteria ferment lactose to lactic acid.

Coliform Bacteria

Optimum growth temperature for Coliform bacteria is 30ºC to 37ºC. They are found in intestines, in
manure, in soil, in contaminated water and on plants. They ferment lactose to lactose to lactic acid and
other organic acids, carbon dioxide and hydrogen and they break down milk protein, resulting in an off
flavor and smell.

Coliform bacteria are killed by HTST pasteurization. They are used as test organisms for routine
bacteriological quality control on dairies. If coliform bacteria are found in milk and pipelines after
pasteurizer, this is a sign of reinfection which indicates that cleaning and disinfection routines need to
be improved. If no coliform bacteria detected, the cleaning is considered as satisfactory.

Butyric acid bacteria

Butyric acid bacteria are very common in nature. They are found in the soil, on plants, in manure, etc.
and easily find their way into milk. The optimum temperature for the growth is 37ºC. they do not grow
well in milk, which contains oxygen.

Propionic acid bacteria

The category of propionic acid bacteria comprise a number of species of varying appearance. They do
not form spores, their optimum temperature is 30ºC, and several species survive HTST pasteurization.
They ferment lactate to propionic acid, carbon dioxide and other products.

Putrefaction Bacteria

Putrefaction Bacteria produce protein-splitting enzymes. They can therefore break down proteins all the
way to ammonia. This type of breakdown is known as putrefaction. Some of them are used in dairy
processing, but most of them cause trouble.

Aseptic Technology
Shelf life and different methods of preservation

Pasteurization of Orange Juice

UHT and Difficulties with UHT

UHT Methods

Sterilization

Sterilizing effect

Self Life

Depends on Chemical, biochemical, physical and Microbiological changes taking place in the product.
We concentrate more on the microbiological Shelf life.

Different Control measures are

Refrigeration:

Storage of product between 0-10º C, Usually used to prolong the shelf life of food products
which are not sterile. Which still

contain Micro organisms.

Deep freezing:

Storage of food at temperature around or below -18°C, microbial multiplication terminates. Shelf life
around one year is achieved.

Chemical Preservation:

adding chemicals to food products preventing the growth and multiplication of microorganisms.
Product is not sterile, living organisms are present but do not increase in number. Very common in High
acid food.

Heat treatment:

application of relative high temperatures for defined periods of time to a food product in order
to reduce or eliminate the microbial load. Two different heat treatments important for us are

Pasteurization and Sterilization.

Pasteurization

Elimination of living pathogens

Mild heat treatment is applied.

LTLT( Long temperature Long time)- 63˚C for 20-30 Minutes. HTST ( High temperature Short time)- 72˚C
for 15 Seconds.-Most Commonly used.

Flash Pasteurization (85-95˚C for few seconds to few minutes)- For High Acid Food and Milk used for
Fermented Dairy Products

Pasteurization of Orange Juice

PRINCIPLE OF PROCESSING ORANGE JUICE

Pasteurization of orange juice is necessary for inactivating enzyme and for destroying microorganisms
capable of growing during storage. If enzymes are not completely inactivated, gelation of concentrate
may occur.

Orange Juice is a high-acid product which limits microbial growth to acid-tolerant bacteria, yeasts and
moulds. Yeasts fermentation is prime cause of microbial spoilage in especially packaged juice. Effective
cleaning procedure are essential in controlling microbial contamination.

A prerequisite for initial high juice quality is in use of whole, undamaged oranges with low microbial
populations. It is essential that high quality concentrate with desired Brix:acid ratio, colour and sinking
pulp content is used. ºBrix determines the volume of single-strength juice that can be reconstituted
from the given volume of concentration.

Quality if water is critical with respect to the content of chlorine, metals, nitrates, salts, air, etc.
Microorganisms and organisms debris, contaminate juice, affect its taste and reduce product shelf life.
However, the main spoilage organisms are not commonly found in water.

Processing: Heat treatment with respect to time-temperature settings should be designed to minimize
unwanted chemical and flavour changes in the product. Oxygen is a very reactive element which can
induce several changes in the chemical composition of orange juice.

UHT

The sterilization process is defined as a UHT (Ultra High Temperature) process if the product is heat-
treated in a continuous flow at a temperature of not-less-than 135°C for a very short time, aseptically
packaged in sterile containers, and has undergone minimal chemical, physical, and Organoleptic changes
in relation to the severity of the heat treatment required for sterilization. 

In other words, the product should have been subjected to a heat treatment having a sufficiently high
lethal effect - so that, after incubation at 30°C ± 1°C for 5 days - no spoilage occurs and the changes in
flavor, odor, color, and nutritional value are minimized.  In addition to ensuring the destruction of micro-
organisms, the heat treatment of milk also results in a number of other reactions and changes.
Choosing the type of process and temperature-time combination best suited to the handling of a range
of products of widely varying initial quality and composition, should be based on the bacteriological and
physio-chemical changes.

Advantages of UHT

High quality:

The D and Z valves are higher for quality factors than microorganisms. The reduction in process time
due to higher temperature (UHTST) and the minimal come-up and cool-down time leads to a higher
quality product.

Long shelf life:

Greater than 6 months, without refrigeration, can be expected.

Packaging size:

Processing conditions are independent of container size, thus allowing for the filling of large
containers for food-service or sale to food manufacturers (aseptic fruit purees in stainless steel totes).

Cheaper packaging:

Both cost of package and storage and transportation costs; laminated packaging allows for use of
extensive graphics

Difficulties with UHT

Sterility:

Complexity of equipment and plant are needed to maintain sterile atmosphere between
processing and packaging (packaging materials, pipe work, tanks, and pumps); higher skilled operators;
sterility must be maintained through aseptic packaging

Particle Size:

With larger particulates there is a danger of overcooking of surfaces and need to transport
material both limits particle size
Equipment:

There is a lack of equipment for particulate sterilization, due especially to settling of solids and
thus over-processing

Keeping Quality:

Heat stable lipases or proteases can lead to flavor deterioration, age gelation of the milk over
time - nothing lasts forever! There is also a more pronounced cooked flavor to UHT milk.

There are two principal methods of UHT treatment:

Direct Heating

Indirect Heating

Direct heating systems

The product is heated by direct contact with steam of potable or culinary quality. The main advantage of
direct heating is that the product is held at the elevated temperature for a shorter period of time. For a
heat-sensitive product such as milk, this means less damage.

There are two methods of direct heating.

injection

infusion

Injection:

High pressure steam is injected into pre-heated liquid by a steam injector leading to a rapid rise in
temperature. After holding, the product is flash-cooled in a vacuum to remove water equivalent to
amount of condensed steam used. This method allows fast heating and cooling, and volatile removal,
but is only suitable for some products. It is energy intensive and because the product comes in contact
with hot equipment, there is potential for flavour damage.

Infusion:

The liquid product stream is pumped through a distributing nozzle into a chamber of high pressure
steam. This system is characterized by a large steam volume and a small product volume, distributed in
a large surface area of product. Product temperature is accurately controlled via pressure. Additional
holding time may be accomplished through the use of plate or tubular heat exchangers, followed by
flash cooling in vacuum chamber. This method has several advantages:

instantaneous heating and rapid cooling

no localized overheating or burn-on

suitable for low and higher viscosity products

Indirect heating systems

The heating medium and product are not in direct contact, but separated by equipment contact
surfaces. Several types of heat exchangers are applicable:

plate tubular scraped surface

Plate Heat Exchangers: Similar to that used in HTST but operating pressures are limited by gaskets.
Liquid velocities are low which could lead to uneven heating and burn-on. This method is economical in
floor space, easily inspected, and allows for potential regeneration.

Tubular Heat Exchangers: There are several types:

shell and tube

shell and coil

double tube

triple tube

All of these tubular heat exchangers have fewer seals involved than with plates. This allows for higher
pressures, thus higher flow rates and higher temperatures. The heating is more uniform but difficult to
inspect.

Scraped Surface Heat Exchangers: The product flows through a jacketed tube, which contains the
heating medium, and is scraped from the sides with a rotating knife. This method is suitable for viscous
products and particulates (< 1 cm) such as fruit sauces, and can be adjusted for different products by
changing configuration of rotor. There is a problem with larger particulates; the long process time for
particulates would mean long holding sections which are impractical. This may lead to damaged solids
and overprocessing of sauce.

Sterilization

In Container Sterilization: Un-sterile Product to Un-sterile container, Hermetically sealed and

subsequently heated to be Sterilized. It usually require 115˚C-120˚C for 20-30 minutes.

In Flow Sterilization: In Aseptic Technology product sterilization is always done by inflow sterilization.
Product is Sterilized before it is packaged in to a container. Product is usually heated up to 135˚C to
150˚C with a holding time of few seconds.

TARGET IS COMMERCIALLY STERILE PRODUCT

COMMERCIAL STERILITY

The absence of disease causing microorganisms, Toxic compounds, microorganisms capable of

multiplication under normal conditions of storage and distribution.

Sterilizing effect

Sterility of food containers and products is controversial.

Sterility implies total absence of all living organisms in any volume of product expressed in terms of semi
logarithmic death rate of microorganisms. That is log x=0

Log x=0(10x=0) does not exist, sterility in absolute sense cannot be achieved, it can only be approached.
Every sterilization must have survivors.

Sterilization procedure is characterized by sterilization effect or efficiency and expressed by the number
of logarithmic (decimal) reductions achieved by the process.

Eg: safe to assume that a normal UHT process achieves nine decimal reduction in milk. Out of 109 spores
fed in to the process one will survive.

109 bacterial spores UHT 100=1 and this is true irrespective of the volume.

Sterilizing effect of sterilizing equipment is determined by usually spores of Bacillus subtilis or spores of
Bacillus stearothermophilus are used as test organisms. Incubation of packs at 30°C and 55°C
recommended to detect them.

Spores of Bacillus subtilis and Bacillus stearothermophilus are generally used as test organisms to
determine the sterilizing effect of UHT equipment, since these strains- especially Bacillus
stearothermophilus- form fairly heat resistant spores.

UHT treatment usually has a sterilizing effect of around 10 to 12 as tested with Bacillus subtilis spores
and around 8 when spores of Bacillus stearothermophilus are used.

The sterilizing effect depends on:

The time temperature combination

The heat resistance of the test spores

The product in which the heat treatment is taking place.

Log (N0/N) =Contact time with sterilant/D

Where N0= Initial number of viable organisms

 N= the viable count after a given time of contact with the sterilant. (Heat or Chemical)

D= decimal reduction time.

(The time needed to achieve one logarithmic reduction in the count of surviving organisms)

Sterility implies the total absence of all living microorganisms in any volume of product.

Expressed in terms of semi logarithmic death rate if microorganisms, this would imply to logx=0 (10X=0)
does not exist, Sterility in absolute sense cannot be achieved; it only can be approached.

Sterilization efficiency: It is expressed by the number of logarithmic (decimal) reductions achieved by

the process.

D-value: Time needed at a given temperature to achieve one decimal reduction in the bacterial spore
count.

F-value: The number of minutes required to kill a known population of micro organisms in a given food
under specified conditions.

Z-value: The increase in temperature which is necessary to reduce the thermal reduction time (D-value)
by one power of 10.

Q10 Value: The increase in the speed of a reaction if the temperature of the system is raised by 10°C.

t= sterilisation time in seconds at T°C

T= Sterilisation temperature in °C

Z= the increase in temperature which is necessary to reduce the thermal reduction time

(D-value) by one power of 10.

Normally the value set as 10.

Fo =1 after the product is heated 121.1°C for 1 minute. To obtain commercially sterile milk from

good quality raw milk a Fo -value of minimum 5-6 is required.

Sterilizing
effect
Introduction to Aseptic Packaging
Common defects observed on UHT products

FLAVOR DEFECTS:

Heat induced=====èCooked, Heated, Caramelized, Scorched

(Sulphur compounds produced by the denaturation of whey proteins are connected with boiled taste of
milk. Large quantities of hydrogen sulphide are present in UHT milk) Millard reaction- HMF (hydroxy
methyl furfural)-reaction between free amino groups and reducing group of lactose)

Lipolysed =====è Rancid, butyric, bitter (Sweet Curdling)

Microbial developments in the milk before heat processing.

Lipolysis and proteolysis are related to survival of heat resistant enzymes.

Milk natural lipase are destroyed by heating, but microbial lipase are considered as 4000 tomes heat
resistant than spores. (Pseudomonas MC 60 protease cause bitter taste in UHT milk)

Off flavors connected to Oxidation:

Increase in the quantities of aldehydes cause oxidized (stale flavor) in milk.

Defects of various origin: =====è Fodder, Grass, Cowy

MICROBIOLOGICAL DEFECTS:

Blown packs: development of gas produced by micro-organisms, mostly due to faulty sealing or
by external damage of the packs.

Incase of juice products, it is by yeast contamination, gas is produced by fermentation.

Coagulation: Mainly by heat resistant spores or by heat resistant enzymes.

Cloudiness, Slimy juice: Usually by mould contamination, never the packs are blown.

PHYSICAL DEFECTS:

Fat Separation: in effective Homogenization (210-280 bars recommended)

Gelation: Caused by the heat resistant enzymes, Mostly microbial origin.