Quick Review on Dairy Development

Vetnepal Review Note 2019-03-15
Quick Review on Dairy Development

QUICK INFORMATION

  • Louis Pasteur, 1856 invented pasteurization
  • June is national l dairy month
  • An enzyme from the stomachs of dairy cattle added to cheese to help coagulate the curds is called as rennet
  • 60:40 is the usual ratio of the amount of milk produced by the rear udder versus the fore udder
  • Myoepithelial are essential for milk letdown
  • Adrenaline hormone blocks milk letdown
  • The hollow cavity found inside the teat called teat cistern

MILK SECRETION PHENOMENON

Mammary gland:

  • Modified sweet gland which is located outside the abdominal cavity
  • Exterior to the udders there is intramam/mary groove
  • Rare quarter is large than front quarter and contains ¼ to ½ more sensory cells
  • Hind quarter produces 60% milk and front quarter produces 40% milk
  • Udder increase 1/3 in size in milking
  • Median suspensory ligament is elastic and divides into 2 halves
  • Lateral suspensory ligament is non-elastic
  • Myoepithelial cells which surround the each alveolus acts for “Let – down’ of milk

Hormones for growth:

  • Estrogen= duct system
  • Progesterone=lobule-alveolar development
  • Prolactin and GH in the last stage of pregnancy

Animals-Teat-duct/teat

  • Bitch:- Teats 5 Pairs - Duct/teat 8-20
  • Swine:- Teats 7 Pairs - Duct/teat 2-3
  • Horse:- Teats 1 Pairs - Duct/teat 2-4

Lactation:

  • Secretion or giving of milk by MG (Estrogen & Progesterone suppression)
  • Prolactin also called as: Lactogen/Lacteotropin/Galactin/mammotropin
  • Residual milk is higher in low producer than HF
    • Milk secretion: Synthesis of milk by epi. Cells (stop after 35hrs of last milking)
    • Lactogenesis: initiation of milk secretion (Prolactin from adenohypothysis)
    • Lactopoiesis: Maintenance of lactation (STH, ACTH, TSH, Oxytocin)
    • Milk ejection: Milk let-down (Oxytocin)
    • Involution; Being normal size

Udder growth:

  • Mammary gland is originate from Ectoderm
  • Mammary gland’s growth 3 times faster than body growth before puberty and pregnant
  • During the 1st month of pregnancy duct system proliferate and from 3rd months onwards secretory t/s proliferate

Nervous system:

  • Parasympathetic fiber not presents in MG.
  • Sympathetic (Help in vasoconstriction/inhibition of secretion) and afferent fiber (help in milk let-down) is present in MG

COMPOSITION OF MILK OF DIFFERENT LIVESTOCK SPECIES

Gross composition of milk:- Water- 87.25%, Dry matter (Total Solid)-12.75% which includes; Fat- 3.8% and SNF-9.5% containing 3.5% Protein, 4.8% Suger and 0.65% Ash.

  1. Cow: Water- 87.0%, Protein, 3.3%, Fat- 4.4%, Lactose 5.0%  and Ash 0.7% .
  2. Buffalo: Water- 82.05%, Protein, 4.0%, Fat- 7.89%, Lactose 5.18%  and Ash 0.79% 
  3. Sheep: Water- 81.23%, Protein, 5.6%, Fat- 7.8%, Lactose 4.4%  and Ash 0.85% 
  4. Goat: Water- 85.71%, Protein, 4.29%, Fat- 4.78%, Lactose 4.46% and Ash 0.76% 
  5. Mare: Water- 90.18%, Protein, 2.14%, Fat- 1.59%, Lactose 6.73%  and Ash 0.42% 
  6. Elephant: Water- 670.8%, Protein, 3.1%, Fat- 19.6%, Lactose 8.8%  and Ash 0.7% 
  7. Bitch: Water- 75.4%, Protein, 11.2%, Fat- 9.6%, Lactose 3.1%  and Ash 0.7% 

Chemical composition of milk:- Generally, milk contains: Amino acids-19 (10 essential and 9 non essential), Fat-11, Vitamins-4+2, Minerals-25, Suger-1, Nitrogenous substances-14 and Phosphate compound-5

FACTOR AFFECTING THE COMPOSITION OF MILK

  • Breeds- Governed by genetic factors (Fat & SNF ∞ 1/Yield) (Fat ∞ SNF) Holsstein-3.45% and Jersey-5.14% fat
  • Species: Genetic make up (Human-3.78%, Dog-9.6%) Fat
  • Day to day variation: Varies with climate, feeding (Fermentation increased-fat decreased) and intervals.
  • Fore milking: Small amount (50-100ml)- 1.2%
  • Middle milking (Maximum amount)-3.5-4%
  • Stripping: Last portion (100-200)ml-6.7%
  • Age: Decline with age (all)
  • Pregnancy: SNF increased and no effect in Fat
  • Excitement: Lower fat
  • Temperature: SNF decreased with increased in temperature and fat increased
  • Exercise: Fat increased, no change in SNF
  • Lactations period: Size of fat globules is bigger in early stage and decline at last stages     
  • Colostrums phase: 0-5 days
  • Normal phase: 6-300 days
  • Extended lactation phase: >300 days (Chlorine is increased)
  • Diseases: Mastitis milk- Chlorine increased, fat, lactose, casein acidity and SNF decreased

Ketosis milk- Fat increased and yield decreased

NUTRITIVE VALUE OF MILK

  • Milk is a perfect/ideal food
  • Milk is deficient in Fe, Cu and Vitamin C
  • Cow milk is deficient in Vitamin D
  • Developed acidity is due to Lactic acid
  • “Goaty flavour’ of goat milk is due to high amount of Caprylic acid in goat’s milk fat
  • Whey protein is albumin and globulin
  • About 80% of protein in milk is Casein
  • Capacity of udder cistern is 400 ml
  • The standard plate count (SPC)/ml of pasteurized milk should not exceed 30,000
  • Protein contain in colostrum: Cow milk-12.8% and Buffalo milk- 21.4%
  • Lactose is 6 times less sweeter, more reactive and less soluble in water than sucrose
  • Khowa is brown colour is due to reaction between sugar and protein called “Mettard reaction”
  • Chedder cheese contains 33% protein weare as Domestiv swis and commonbert cheese contain (26-30%) and 19% protein respectively
  • Fat= Provide flavor and palatability
  • Carotene= Gives milk as yellow colour
  • Riboflavin= Gives whey green yellow colour
  • Casein= Gives milk as a white colour
  • Xanthophylls= Gives yellow colour of egg yolk

PHYSIOCHEMICAL PROPERTIES OF MILK

a) Physical state of milk

  • Water – solvent
  • Lactose + protein of minerals – in solution form
  • Protein + other minerals –Colloidal form
  • Fat- emulsion form (Oil in water)

               b) Colour

  • White to golden yellow, depends upon breeds, fat and solid materials
  • White colour- due to reflection of light through fat globules
  • Yellow colour is due to carotene present in milk (in green grass)
  • Bluish yellow colour is due to riboflavin pigment
  • Green colour of whey is due to fewer amounts of fat particles

c) Flavour and test

  • It varies acc. to animal’s species, feed and fodder
  • Sweet taste is due to Lactose and Salty taste is due to minerals
  • Sour taste is due to lactic acid and butyric acid

d) Acidity and pH

  • pH of milk=6.4-6.9 (Blood pH-7.05)
  • pH is increased in mastitis and decreased in colostrums or developed acidity
  • Acidity of fresh milk is (0.13-0.17) % due to casein, citrate, phosphate and CO2 which is also called natural or apparent acidity
  • Developed acidity (>0.17%) is due to fermentation of lactose to lactic acid through lactobacilli (Limit of acceptance is 0.20%

e) Specific gravity

  • It is measured by wt. of milk/wt. of same volume of water in the same temperature
  • It is measured by lactometer (Sp. Gr.=1+CLR/1000)
  • Sp. Gr. of cow milk – 1.028-1.030
  • Sp. Gr. of buffalo milk – 1.030-1.032
  • Sp. Gr. of skim milk – 1.035-1.037

Sp. Gr. of water = 1.0, Protein = 1.346, Lactose = 1.666, Minerals = 4.12, Fat= 0.93, SNF = 1.616

f)       Refractive Index: Measured by Refrectometer, RI of milk is 1.35

g)      Surface tension: (45-46) dynes/sq cm

h)      Boiling point: A solution boils at higher temperature than pure solvent. BP of milk in normal temperature is 100.170C

i)        Freezing point: A solution freeze at lower temperature than pure solvent. FP of milk in normal temperature is (0.54-0.55)0C

j)        Specific heat: Water is 1.0, Fat-0.5, Protein-0.5, Lactose-0.3, Ash-0.7, Cream-1.05, Whey-0.98 and milk-0.938

k)      Viscosity: The significant of viscosity is due to casein and fat globules globules. It is measured by Viscosimeter. Milk=1.5-2.0 centipoise (CP=1/100 centipoise)

l)        Electric conductivity: 0.004-0.0055 ohms

  • Milk + acid=fermentation (Dahi)
  • Milk + enzyme=Coaulation (Rennin)
  • Milk + Yeast=Alcohol (Summer cream)
  • Milk + Bacteria=Off flavuor
  • Adhesives properties is due to the casein

PASTEURIZATION AND HOMOGENIZATION OF MILK

Homogenization: Process of passing the milk under the high pressure (2000-5000 psi) at a velocity of (600-800) ft/sec through small orifice therefore causing subdivision of fat globules.

  •  High pressure homogenizer
  •  Low pressure homogenizer
  •  Sonic vibrator type homogenizer

Pasteurization:

  • First discovered by Louis Pasteur in 1860-1870 by heating wine in 50-600C killed spoilage organisms
  • It is the process of heating each and every particles of milk to a temperature of at least 630C for 30 minutes or 71.50C for 15 seconds or any time and temperature combination.
  • It is also called as Continuous method (HTST) and Batch method (LTLT). 1450F for 30 minutes or 1610F for 15 seconds
  • Pasteurization kills 100% of pathogenic and 85-99% of spoilage bacteria
  • Process includes Heating, Holding and Cooling (immediately to 50C)
  • It also destroys the 20% of vitamin C.

HYGIENIC MILK PRODUCTION

 CMP is always profitable for producer, manufacturers & consumers due to the following reasons:

  • Producer’s interest
  • Manufacturer’s interest
  • Consumer’s interest

Methods of CMP

  • Health of the herd
  • Clean animals
  • Clean surrounding
  • Control flies-can carry typhoid, dysentery and other contagious diseases
  • The milkers’ cleanliness
  • The types of milk pan-Sanitary milking pails with dome shaped top should be used instead of open buckets or vessels during milking
  • Straining: To remove sediment
  • Feeding: Should be made an hour before milking. At the time of milking for the purpose of keeping milking cow busy, provide only concentrates which will be less dusty.
  • Cool & store milk properly: In winter-keeping in cold water & in summer ice cubes may be used.

Bacteriological standard of cow milk

  • Not exceeding- SPC/ml 2, 00,000 = Grade very good
  • Between- SPC/ml 2, 00,000-10,10,000 = Grade good
  • Between- SPC/ml 10, 00,000-50,10,000 = Fair
  • Over- SPC/ml 50, 00,000 = Grade Poor

The pasteurized milk should not exceed SPC/ml over 30,000