09 - Chapter 3 PDF
09 - Chapter 3 PDF
09 - Chapter 3 PDF
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3.1 Introduction
industry. Producing high quality milk requires effective udder health programs
at a herd level (Bhutto et al., 2010). The safety of milk is an important attribute
for consumers of milk and dairy products. Milk and products derived from
dairy farm environment and due to excretion from the udder of an infected
raw milk into dairy food processing plants can lead to persistence of these
dairy products. These pathways pose a risk to the consumer from direct
great concern around the world. This is especially true in developing countries
where production of milk and various milk products takes place under
indicates the hygiene practiced during milking, like cleanliness of the milking
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the udder of the individual animal (Spreer 1998; Gandiya 2001). Milk from a
healthy udder contains few bacteria but it picks up many bacteria from the time
it leaves the teat of the cow until it is used for further processing. These
milking till consumption and the quality of the milk. Milk produced under
hygienic conditions from healthy animals should not contain more than 5 x 105
possible contamination of bacteria either from the udder, milk utensils or water
supply used (Bonfoh et al., 2003). Fresh milk drawn from a healthy cow
normally contains a low microbial load (less than 1000 ml-1), but the loads may
mastitis milk with fresh clean milk may be one of the reasons for the high
The current research includes all the independent factors that are able to
affect the food safety level of the end product of the whole dairy chain, i.e., the
considered, i.e., transport of raw milk to the processing factory, and delivery of
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Agriculture is the base of Indian economy. Livestock production
Dairy plays a dynamic role in Indias agro-based economy. Today, India ranks
the first in the world in terms of milk production. In Goa, there is ample scope
for income generation through livestock production. The territory has about
quality assessment and improvement which will result in longer shelf life
practices for small-scale farmers who produce fresh milk and sell it to local
quality and safety of locally produced raw milk and to identify the relevant
sources of contamination and critical point in the chain of locally produced raw
bovine milk.
3.2.1 Samples
per the standard protocols. A total of 933 samples comprising of milk from
milking utensils, dairy cooperative society (DCS), receiving dock and bulk
coolers) and swabs from cans and milk processing line within Goa region were
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collected during 20062009. For collection of the samples, the udder was
washed with antiseptic solution, wiped dry with clean cloth (Fig 3.1) and then
disinfected with cotton ball dampened with 70% alcohol, the foremilk was
Table 3.1. Details of samples collected from different sources for analysis of
microbiological parameters.
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The samples were collected after the cleaning and sanitation of the plant as per
Samplings were done at quarterly interval (January, April, July and October).
Prior to milking, the contamination of the surface of the material and the
water. A total 60 swab from cans and milk processing line and 15 milk
All the samples were collected in sterile screw cap tubes. Samples
were collected early in the morning at udder, milking utensils, and dairy
cooperative society levels. For sampling at udder level, milking animals were
the can from the same cow; from this can second milk sample was collected.
When this can reached at DCS, third sample was collected. At DCS the milk
got transferred in another big can (Fig 3.2), which came to receiving dock at
processing unit, where fourth sample was collected. All the samples were kept
transportation to the processing unit was also assessed. At each visit, farm
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Fig 3.2. Filtering of milk after receiving at dairy cooperative society.
California mastitis test (CMT) was carried out according to the method
bromocresol purple added in 100ml distilled water). Each quarter milk samples
from the cow was collected in cups of the CMT paddle. Equal amount of the
CMT reagent was added to quarter milk samples. As the CMT paddle was
interpreted: in brief, scores were given within the range 04, with 0 for no
positive.
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3.2.2.2 Methylene Blue Reduction Test
to the IDF (1990). One ml of methylene blue was added to 10 ml of each of the
raw milk samples, shaken. The test tubes were then incubated at 370C in hot
water bath for 30 min and the change in color was carefully observed. In case
the methylene blue decolorized during the incubation period, the MBRT was
Total microbial count was carried out as described in IS: 5402-2002. For
(Himedia, Mumbai) and appropriate dilutions were plated on plate count agar
using the spread plate method. The plates were incubated at 370C for 24 h for
aerobic mesophilic counts. The enumerations were done as per ICMSF (1978).
2002 was used. The market milk samples were serially diluted in peptone
MacConkeys agar using the spread plate method. The plates were incubated at
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3.2.2.5 Swabs
A total of 60 swab samples were also collected from cans and milk
processing line. The swab samples were collected in sterile saline and then
transported to the laboratory for further analysis. Both total plate and coliform
exposing nutrient agar plates inside the sheds for 10 min. The lid of the petri
370C to study the bacterial count and airborne emission to the immediate
environment.
The data was analysed using paired t-test using statistical package
WASP.2 (www.icargoa.res.in).
containers for milking the animals. The milk passed through at least four to
five containers, two funnels and two sieves before reaching the container,
udders was a common practice. Milk samples were collected for bacteriology,
and the CMT was performed cow-side. In this study, subclinical mastitis
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(SCM) was found in 23.8% of the animals (at least one positive quarter per
(varying from 10-50% in cows and 5-20% in buffaloes) than clinical mastitis
(1-10%) (Joshi and Gokhale, 2006). In another study, of the 507 milk samples
(Adesiyun, 1994). The California mastitis test (CMT), first described and used
in 1957 (Schalm and Noorlander, 1957), has been accepted as a quick, simple
test to predict somatic cell count (SCC) from individual quarters or composite
milk (Sanford et al., 2006). The CMT is an inexpensive, fast and cow-side test
increasing SCC or total leukocyte count in milk, the CMT score also increases
(Schalm and Noorlander, 1957; Dohoo and Meek, 1982). At the cow-level, the
sensitivity and specificity of the CMT (using the four quarter results
heifers from 23 dairy herds Holstein heifers, at the quarter level, the
identify all IMI. However, at the heifer level sensitivity and specificity of CMT
identification of IMI. SCC can be useful for detecting IMI and is cheaper than
cultures (Sargeant et al., 2001). CMT scores at drying off might be good
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isolation of major pathogens and the CMT score in milk samples obtained one
week before and those at drying off has been reported (Bhutto et al., 2010).
The California Mastitis Test has previously been adapted for use in an
inline, cow-side sensor and relies on the fact that the viscosity of the gel
(Verbeek et al., 2008). The CMT has been reported to play a useful role in
dairy herd monitoring programs as a screening test to detect fresh cows with
from the farm to the processing unit. The reduction time was significantly
correlated (P < 0:001) with the critical control point of milk collection in the
chain i.e., between udder and dairy cooperative society, and udder and
the udder to the processing point. Estimation of microbial load in raw milk is
crucial in relation to its spoilage and keeping quality. Several techniques are
currently available for determining the total viable cell count as well as
microbial load including the laboratory methods for determining total viable
cell count include direct microscopic count (DMC), most probable numbers
(MPN), and standard plate count (SPC) (Ahmed and Jindal, 2006). However,
the most frequently used methods for indirect estimation of the microbial load
in raw milk in the dairies and milk collection centers are based on dye
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(MBRT) is widely used at the milk collection centers (Ahmed and Jindal,
2006).
In the present study, the total viable counts varied from <103 to
The data is presented in Table 3.2 and Fig. 3.3. The total counts at udder level
and for samples from milking utensils differed significantly (P<0.005) from
that of receiving dock level. Similar findings were reported by Godefay and
cow's milk taken at different sampling points from four dairy farms and a milk
collection centre. A high increase in the mean total aerobic plate count was
observed in milk samples taken from the bucket (1.1 x 105 CFU/ml), storage
container before cooling (4 x 106 CFU/ml) and upon arrival at the processing
Table 3.2. Average total plate counts in cfu/ml of milk samples at different
levels (season wise)
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Lack of knowledge about clean milk production, use of unclean milking
equipment and lack of potable water for cleaning purposes were some of the
factors which contributed to the poor hygienic quality of raw milk in the study
farms (Godefay and Molla, 2000). The total aerobic plate count per ml of pre-
processed raw milk was found to be high ranging from 5.8 x 105 to 5.7 x 108 in
Trinidad (Adesiyun, 1994). The average total viable counts of can rinse were
3.11x106. Fresh milk drawn from a healthy cow normally have a low microbial
load, but the loads may increase up to 100 fold or more once it is stored for
mastitis milk with fresh clean milk may be one of the reasons for the high
microbial load of bulk milk (Jeffery and Wilson, 1987). Highest microbial load
occurred during summer season, while the lowest counts occurred during
winter season. The total counts of the samples collected during October at
udder level were significantly different from the counts of the samples
collected during January (Table 3.3; Fig 3.4). Also the total counts of the
counts of the samples collected from milking utensils during April. The
indicated increased microbial growth. It was observed that the load of the
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Table 3.3. Average total plate counts at different levels of collection.
Uten.
microorganism was high in raw milk in all seasons. The high microbial load
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microorganism increasing microbial load. In some cases, from DCS to dock
microbial load increased by 1-3 log unit per ml. Enumeration of mesophilic
aerobes (MA) is the main quality and hygiene parameter for raw and
In this study, the coliform counts of the market milk ranged between <
were 0.73x104 for aluminum cans, 0.23x104 for steel cans, and 6.33x104 at
processing lines (Table 3.4). The average total counts of milk samples from
bulk coolers were 4.5x105. The detection of coliform bacteria and pathogens in
udder, milk utensils or water supply used (Olson and Mocquot, 1980; Bonfoh
et al., 2003). While determining the total coliform counts in 250 samples of
Coliforms were detected in 62.3% of 131 bulk tank milk samples in eastern
South Dakota and western Minnesota (Jayarao and Wang., 1999). In a study in
Zimbambwe, the coliform counts ranged from <10 to 6.0x103 CFU/ml; 10% of
milk samples on delivery had more than 103 CFU/ml coliform counts (Gran et
al., 2002).
count (CC) in dairy farms (n = 10) indicated geometric mean in-line milk CC
CFU/ml (Pantoja et al., 2011). Rate of fall-offs, rate of cluster washes, outdoor
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and indoor temperature, indoor humidity, sampling duration, and parity group
between liner CC, rate of cluster washes, rate of milking units fall-offs, and
ILCC indicated that managing and monitoring such events had the potential for
three smallholder dairies in Zimbabwe 83% utensils used for milking had >300
cfu per 20 cm2 (Gran et al., 2002). In order to reduce contamination of the
milk, utensils used for milking should be rinsed, cleaned using detergent and
disinfected immediately after use (Dodd & Phipps, 1994; FAO and WHO,
1997b; IDF, 1990). The use of detergents and good quality water for cleaning
Use of disinfection, either chemical or hot water, would mostly reduce the
and their hygiene practice in milk handling could be expected to influence the
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The mean value of total bacterial count in the barn air was 1.73 x 103
with minimum of 1.5 x 102 and maximum of 2.1 x 104. Earlier study
(Matkovic et al., 2006) reported the mean value of total bacterial count in the
barn air ranging from 2.82 104 CFU/m3 at noon to 7.76 104 CFU/m3 in the
directly influenced by air temperature, relative humidity and air flow velocity,
and also could be attributed to daily animal and human activities in the barn
(Matkovic et al., 2006) whereas, the outdoor air bacterial emission depends on
the source of contamination, position of air outlet on the barn roof or wall,
primary source being the animals themselves, then the fodder and humans.
Bacteria are only one of the many groups of air pollutants. Bacterial count may
housing, and feeding, grooming, milking, and other activities (Lange et al.,
Bacterial count in the air of a dairy barn may provide appropriate data
on the hygienic condition at the farm from where milk starts on its way to the
consumer. In addition, for the assessment of the effect of dairy barns on the
local environment, bacterial count in the barn air and monitoring of its
emission from the barn to the adjacent environment are important parameters
(Matkovic et al., 2006). Seasonal changes in airborne fungi, bacteria and in the
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animal feeding operation has been reported in the southwest United States
(Alvarado et al., 2009). High spore counts can occur at the dairy farm and feed
and milking equipment can act as reservoirs or entry points for potentially
highly heat-resistant spores into raw milk (Scheldeman et al., 2005). Good
hygienic measures could probably reduce the contamination level of raw milk,
spoilage of milk and dairy products. In view of the current concerns of effects
importance to allow the dairy or food industry to adequately deal with newly
under strict hygienic conditions. Ideally all the milk leading to the dairies
should be bulk cooled. Possible cooling at DCS will decrease the load of
microorganisms.
regarding the different areas of animal health, animal welfare and food safety.
Monitoring animals, farm conditions and farm records can be extended with
risk identification and risk management. The hazard analysis critical control
the production process on the areas of animal health, animal welfare and food
safety.
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An integrated approach to controlling food safety throughout the entire
greater food safety level for consumer products (Valeeva et al., 2004). In line
with these ideas about food safety, a number of countries have developed and
introduced new regulations to assure food safety at different stages of the food
safety should focus not only on assuring safe food production within a single
The health of the dairy herd, milking and pre-storage conditions are
study the bacteriological counts in milk due to unclean udders was low but
increased the count of microflora in milk. The use of unclean milking and
transport equipment contributed also to the poor hygienic quality of the milk.
These observations are in line with findings in Ethiopia (Godefay and Molla,
The number of containers used in the milk chain was the main source
refrigeration and poor standard of hygiene means that milk, which often
contains a large number of bacteria, acidifies on its way to the processing unit.
importance to the economy of the farmer and the sustainability of the dairy
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Microbial contamination of raw milk may occur from 3 main sources:
organism transfer via dirty udder and teat surfaces, and from improperly
prolonged storage of milk can also influence bacterial count by increasing the
It was observed that the period between time of collection of milk and its
transportation to the processing unit was critical for change in microbial count.
The milk produced at farmers field was of the best quality except on few
contamination. Presence of mastitis increases the microbial count of the raw milk.
As far as possible the time duration between milking and arrival of milk at
established at far off places for initial cooling of milk so that the bacterial
animals, shed, utensils and the milking personnel all contribute to the quality of
milk. A backward linkage of quality of milk and status of animal health together
with the milking surroundings need to be established. This will help in taking
corrective actions and breaking the unhealthy link. High microbial counts and
the occurrence of pathogens are likely to affect the keeping quality and safety
that training and guidance should be given to farms owners and their workers
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with contaminated raw milk should be extended to the public, so that
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