Milk
1Carbohydrate
breakdown(souring,fermentation).Lactose to lactic acid+alcohols.Casein
coagulates at low pH-Curdling leaving whey.Pasteurized milk spoils differently
2Protein
breakdown(proteolysis)-1st amino acids,unpleasant smelling
gas(H2S),"putrid"
3Fat
breakdown(lipolysis)production of fatty acids+glycerol catalysed by
lipases(soapy,rancid)
Beneficial
changes-cheese manufacture-Acid production(by rennet),curd is
obtained&heated&separated from whey,pressed into blocks&allowed to
maturate