milk chemical composition Flashcards
milk fat
- pleasant taste of milk and aroma, consistency and texture
- hydrolysis of milk fat = glycerin formed
- oxidation = ketones formed
lactose
- important for sweetened condensed milk
basic milk proteins
casein, albumin, globulin
protein present in milk
casein and whey
whey protein
prevents coagulation
very sensitive to heat
denaturation = 60oC
enzymes
lipase
phosphatase
peroxidase
catalos
reductase
endogenous enzymes
from mammary gland, native milk enzymes
exogenous enzymes
from MO and not considered normal pat of milk
physical properties of milk (6)
- milk acidity
- milk density
- surface tension of milk
- freezing point (-0.5oC)
- viscosity
- refraction index of light
milk acidity
- natural acidity = after milking pH 6.6, phosphate and carbonates give alkaline character
- formed > lactose > lactate by LAB
- titratable acidity - total natural and formed acidity
milk errors
colour change
change in taste and smell
change of appearanceo
colour change
- nutrition nd disease
red milk
- blood
- plants (blade, sieve, buttercup)
- MO (serattia and micrococcus)
yellow milk
- more carotene
- plants (saffron)
- drugs (tetracyclines)
- MO (pseudomonas, sarciria)
- disease (lepto + jaundice)
brown milk
- bleeding in udder, MO
blue milk
- nutrition (plants)
- MO
changes in taste and smell
forage, disease medicine, MO, enzymatic process, foreign odour and oxidation
bitter milk
food (beets, canola)
MO (pseudomonas, proteus)
physiological (oestrus and end of lactation)
salted milk
colostrum
non-specific udder inflamamtion
heated smell and taste
end of lactation
oestrus
mastitis
change of appearance
mucus
- physiological (colostrum)
- E.coli
- disease (sepsis, FMD, anthrax)
foaming
- physiological (before drying)
- food (more potatoes)
- MO
