EVALUATION METHODS FOR QUALITY AND PRICE OF
MILK AND DAIRY PRODUCTS
Young W. Park
Agricultural Research Station Fort Valley State University Fort Valley, GA 31030-4313 And
Department of Food Science and Technology The University of Georgia Athens, GA 30602
Production of Quality Goat Milk and Its Products
Fresh and normal goat milk from healthy, properly fed and milked animals, is a white, opaque liquid with a slightly sweet taste which has practically no odor (Le Jaouen, 1987). Production of quality goat milk should start at every farm level, because flavor and quality of the milk cannot be improved later in the processing stage (Park and Guo, 2006). The basic principle is that the better the milk, the better the processed products (Peters, 2000; Park and Guo, 2006). Milk quality is negatively affected by improper handling from many factors such as feeding, handling of animals prior and during milking, handling of the milk during and after milking, cooling and transportation, pasteurization, processing, packaging, and processing utensils (Peters, 1990; Haenlein, 1992). Off-flavor in goat milk can be attributed to the feeds, weeds, forages, chemicals, building materials, colostrum, estrus, mastitic milk, filthy utensils and strainer, unclean milking equipment, slow cooling, odors from bucks, barn and/or milk room. Good management of the entire farm system leads to good quality milk. The recommended milking procedure has to be practiced in a daily routine, maintain functioning and sanitary equipment, have healthy animals, and use recommended detergent, acid and sanitizers for cleaning and milking equipment.
Five major parameters are routinely checked by regulatory agencies for
quality raw milk production
1. Nutritional constituents in milk. 2. Somatic cell counts as related to mastitis. 3. Bacteria counts as related to sanitary
practices. 4. Adulteration and pesticide residue contents. 5. Flavor, taste, appearance and temperature.
Quality of Raw Milk tested by Individual Dairy Processing Plants
1. Standard plate count (SPC) 2. Direct microscopic count (DMC) 3. Freezing point determination (Cryoscope) 4. Presence of inhibitory substances (antibiotic screening test) 5. Sensory evaluation 6. Preliminary incubation (PI) – SPC 7. Direct microscopic somatic cell count (DMSCC) 8. Acid degree value (ADV) 9. Laboratory pasteurization count (LPC) 10. Thermoduric spore count 11. Fat content 12. Total solids content (can also include protein content) 13. Sediment test
Filteration of farmstead milk for further processing (Le Jaouen, 1987)
3M Petrifilm Plate Techniques
ADGA members on National Conference Interstate Milk Shipments On the Problem of Somatic Cell Count legal thresholds:
1. The Coulter Counter is not reliable for goat milk. 2. The only officially acceptable method to confirm high
cell counts in goat milk is the DMSCC using the special pyronine Y-methyl green stain (Standard Methods/Dairy Products 1985, pp. 229-230), or another appropriate method determining DNA contents. 3. The Fossomatic counter may be accurate in midlactation, but results need to be confirmed with the pyronine-Y stain method.
ADGA members on National Conference of Interstate Milk Shipments On the Problem of Somatic Cell Count legal thresholds: (Cont’d)
4. The CMT can be used as a screening test but high counts must be confirmed with the pyronine-Y stain.
5. SCC levels of normal goat milk increase from Spring to Fall well above the cow threshold of 1 million/ml, starting about 4 months after kidding, coinciding with start of estrus and late stage of lactation.
6. Easily achievable SCC levels of 100,000 – 300,000 SCC/ml in cow milk are unusual in even high quality managed goat herds.
Total Aerobic Plate Count
E. coli and Coliform counts
Yeast and Mold counts
Staphylococcus aureus count
Grade A raw milk for pasteurization
Temperature:
Cooled to 45oF (7oC) or less within two hours after milking, provided that the blend temperature after the first and subsequent milkings does not exceed 50oF (10oC).
Bacterial limits:
Individual producer milk not to exceed 100,000 per ml. prior to commingling with other producer milk. Not to exceed 300,000 per ml. as commingled milk prior to pasteurization.
Antibiotics:
Individual producer milk: No detectable zone with the Bacillus subtilies method or equivalent. Commingled milk: No detectable zone by the Sarcina lutea Cylinder Plate Method or equivalent.
Somatic cell count: Individual producer milk. Not to exceed 1,500,000 per ml.
Grade A pasteurized milk and milk products
Temperature: Cooled to 45oF (7oC) or less and maintained thereat.
Bacterial limits: 20,000 per ml.*
Coliform:
Not to exceed 10 per ml.: Provided that , in the case of bulk milk transport tank shipments, shall not exceed 100 per ml.
Phosphatase: Less than 1 microgram per ml. by the Scharer Rapid Method or equivalent.
Antibiotics:
No detectable zone by the Sarcina lutea Cylinder Plate Method or equivalent.
Effect of Somatic Cell Counts on Cheese Yield
\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_
Low group High group Difference .
Wisconsin mastitis test score
11
16
5
Somatic cell count (cells/ml) 529,000 667,000 138,000
Cheese yield potential (lbs/cwt) 9.52
9.26
0.27
Gross margin/cwt
$ 2.01
$ 1.78
$ 0.23
\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_
Terms for Milk Quality – Cont’d
B. Measurement of acidity of milk:
1. Titratable Acidity:
a. It is determined by adding NaOH (0.1 N) solution to raise the pH of the milk to about 8.3.
b. One ml of the base equals 0.1% lactic acid. c. %TA = ml 0.1 N NaOH x .009 x 100/gram of sample
2. SH (Soxhlet-Henkel) value:
a. It indicates how many ml of NaOH (25 mol/ml) are required to neutralize 100 ml of milk. One ml of 2% alcoholic phenolphthalein solution is added as indicator.
b. SH value of fresh milk ranges 6.4 – 7.0 c. SH value of raw milk <5.0 indicates mastitis. d. SH values of 8.0-9.0 gives sour taste, and coagulate.
Table 1. Minimum Pasteurization Temperature and Times
\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_
Product
Temperature
Time
\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_
1. Milk
145oF (62.8oC) 30 minutes
LTLT
161oF (71.7oC) 15 seconds
STHT
191oF (88oC) 1 second
UHT
194oF (89oC) 0.5 second
201oF (94oC) 0.1 second
204oF (96oC) 0.05 second
212oF (100oC) 0.01 second
2. Milk products of 10% fat or more or added sugar (half/half, cream, chocolate milk)
150oF 166oF 191oF 194oF 201oF 204oF 212oF
30 minutes 15 seconds 1 second 0.5 second 0.1 second 0.05 second 0.01 second
3. Eggnog and Frozen dessert Mixes
155oF 175oF 180oF
30 minutes 25 seconds 15 seconds
M icrobiological Standards for Some Grade A Dairy
Products (FDA Grade A M ilk Ordinance & Code 1, 1978)
Product
Standard Plate Count/ml
Coliform
C ount/m l
---------------------------------------------------------------------------------
Raw milk, at pickup
100,000
no standard
Raw milk, at balance
Tank of pasteurizing unit 300,000
no standard
Pasteurized milk and
Milk products
20,000
<10
Condensed milk
30,000
<10
Cottage cheese; wet, dry- ; <5,000-<20,000
<10
W hey
30,000
<10
Ice Cream
<20,000-<50,000
<10
Butter
<5,000-<20,000
-
Milk powder
<20,000-<50,000
no standard
Non-fat dry milk
30,000
<10
.
Quality Evaluation of Dairy Products/Cheeses
Quality of dairy products are changed during manufacturing, refrigeration, distribution and storage.
Qualities of all dairy products including cheeses are influenced by several parameters, such as chemical, microbiological, rheological and sensory scores of the products.
Proteolysis and lipolysis are two primary processes in cheese ripening with a variety of chemical, physical, microbiological, textural, and rheological changes which occur under controlled environmental conditions.
Studies showed that cheese quality is greatly influenced by levels of peptides, amino acids, and free fatty acids resulting from proteolysis and lipolysis.
pH
6 5.5
5 4.5
4 3.5
0 2 4 8 16 24 Aging Period (wk)
Plain soft Pepper soft Caciotta Monterey Jack Goat Cheddar Cow Cheddar Ripened Cow Cheddar
% WSN
35 30 25 20 15 10
5 0
0 wk 8wk 16wk 24wk Storage Time
Plain Soft Caciotta Monterey Jack Goat Cheddar Cow Cheddar
ADV
7 6 5 4 3 2 1 0
0 2 4 8 16 24 Aging Period (wk)
Plain soft Pepper soft Caciotta Monterey Jack Goat Cheddar Cow Cheddar Ripened Cow Cheddar
Milk Pricing System
A. Butterfat differentials Pricing
Butterfat differentials are the amount by which the price of farm milk is increased or decreased for each “point” (0.1%) of butterfat test.
The procedure used to calculate butterfat differentials in most US Federal Milk Order markets is to multiply the average wholesale price by 0.115 at Chicago, effective Dec. 1, 1983 (USDA support price for Grade A butter is $1.4325/lb)
At this price, the butterfat differential for farm milk is approximately 16.5 cents (1.4325 x 0.115).
Use of butterfat differentials to price farm milk assumes that fat and solids-not-fat prices and contents fluctuate together.
Milk Pricing System
B. Component pricing
Milk fat and protein are the two major variable constituents in milk.
Lactose remains fairy constant at about 5%, and minerals at about 0.7%, but protein and fat vary considerably between seasons.
On the average, farm cow milk contains about 3.7% milk fat and 8.55% solids-not-fat, including about 3.2% protein.
A one point (0.1%) change in milk fat test is normally associated with as 0.4 point (0.04%) change in solids-not-fat, and in protein.
Milk Pricing System
C. In Component Pricing System, goat milk farmers have a disadvantage with protein: - Goat milk has higher N content than cow milk, but
the former has higher nonprotein nitrogen, which gives good health benefits, but implicated with a lower milk pricing.
D. Calculation of 4% fat-corrected milk (4%FCM)
4% FCM = 0.4 x kg milk yield + 15 x kg fat yield
Milk Pricing System
E. Product Prices
The USDA purchase prices for butter, nonfat dry milk, and Cheddar cheese are calculated from the support price for milk. During the period of October, 1980-December 1, 1983; The purchase price for butter, $1.49/lb; nonfat dry milk, $0.94/lb; and Cheddar cheese, $1.395/lb ($1.8628/lb; 1998)
Per Hundredweight Milk;
a) A gross price to plants per hundredweight of milk is $14.32.
a) 4.48 lbs butter x $1.49 = $6.68 butter value in 100 lbs milk.
b) $14.32 - $6.68 = $7.64/8.13 = $0.94/lb USDA purchase price for nonfat dry milk.
Average performance of dairy GOAT BREEDS in different countries
\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_
Country
Lactation
Yield (kg)\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_
Goat breed
length (day)
Milk
Fat
4% FCM\_\_\_\_
Cyprus
Damascus
255
510
20
504
France
Poitevine
230
520
20
508
Greece
Native
230
160
9
199
India
Jamunapari
220
215
9
221
Norway
Nordie
275
650
24
620
Switzerland
Saanen
282
745
26
688
Turkey
Kilis
270
270
13
303
USA
Alpine
288
869
31
813
Nubian
288
710
32
764
US Toggenburg
292
870
30
798
\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_
(Haenlein, 2007)
Average performance of dairy SHEEP BREEDS
\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_i\_n\_\_d\_i\_f\_f\_e\_r\_e\_n\_\_t\_c\_o\_\_u\_n\_\_t\_r\_ie\_\_s\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_
Country
Lactation
Yield (kg)\_\_\_\_\_\_\_\_\_\_
Sheep breed
length (d)
Milk
Fat 4% FCM\_\_
Czechoslovakia
Prmenka
162
162
12
245
France
Lacaune
165
270
20
408
Germany
East Friesian
300
632
41
868
Greece
Chios
210
218
17
342
Israel
Israel Awassi
270
495
33
693
Italy
Comisana
150
132
11
218
Spain
Manchega
210
300
28
540
Turkey
Awassi
120
168
11
232\_\_\_\_
Haenlein (2007)
Comparative profitability of two systems of goat farming
\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_
GREECE
Intensive farming
Extensive farming
\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_
Gross return/goat/year, $
134.94
66.24
Expenses/goat/year, $ Labor, % Feed, % Capital, % Housing, % Others, %
110.89 39.1 42.8 12.2 4.4 1.5
58.69 51.8 31.6 13.4
2.1 1.1
Net return/goat/year, $
24.05
7.55
\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_
Comparative profitability of
two systems of goat farming
\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_
FRANCE
Milk sold from farm
Cheese sold from milk on farm
\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_
Milk production/goat/year, kg
553
461
Price/kg milk, $
0.40
0.94
Gross return/goat, $
243.83
584.00
Production cost/goat/year, $
118.17
190.83
Net return/goat/year, $
125.66
393.17
\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_
ITALY
Net return/goat/year, $
74.93
112.00
\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_
USA
Average herd production,
kg milk/goat/year
Break-even price/kg milk
\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_
680
0.52
907
0.39
\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_
CONCLUSIONS
1. The basic principle for production of quality dairy products is the better the original milk, the better the processed products.
2. Milk is highly perishable, and its quality is easily deteriorated by improper handling of feeding, animals prior and during milking, handling of the milk during and after milking, cooling and transportation, pasteurization, processing, packaging, and processing utensils, etc.
CONCLUSIONS – Cont’d
3. Each processing plant should establish appropriate quality control systems for each point of manufacturing facilities.
4. All personnel involved (farm level, transport, dairy plants) in production, processing, distribution, and marketing of dairy products must follow the required regulations (PMO) enforced by appropriate regulatory agencies (e.g. FDA, APHA).
5. Four important requirements for Grade A dairy products are: i) safe to drink, ii) good flavor, iii) relatively free from spoilage bacteria and somatic cells, and iv) composition.
THANK YOU!!
Ver+/-
