Milk as commodity

Milk as commodity

• 1.
  MILK Objective of thetopic •Know the processing of milk •Identify various types of milk •Understand pasteurization and homogenization
• 2.
  Introduction  Milk generallyrefers to milk from cows,in certain parts of the world the milk of camels, sheep, buffall or mares also plays an important role.  Milk( lait) is a nutritious food. It is very commonly used in many dishes such as soups, sauces, puddings, desserts, cakes and for hot & cold drinks  Milk has sugar called lactose and this is the reason why milk changes colour when heated for long time.
• 3.
  Composition of milk Constituents Percentagepresent in milk Proteins 11 Fats 3-6 Minerals 1 Vitamins 1 Carbohydrates 2 Water 82
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  Processing of milk To ensure safe milk free from disease- producing bacteria, toxic substances and foreign flavours, fresh whole milk is to be processed before marketing. milk processing operations consist of :- Clarification Pasteurization Homogenization
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  Clarification  Noticeable quantitesof foreign materials, such as     paricles of dust, dirt and many undesirable sustances . To remove this , milk is generally passed through a centrifugal clarifier. The speed of the clarifier will be such that there is little seperation of cream This operation removes all dirt, filth, cells from udder and some bacteria. Clarification does not remove all pathogenic bacteria from milk.
• 6.
  Pasteurization  Pasteurization isthe heating of liquids, to high temperature improves their keeping quality.  The aim of pasteurization of milk is to get rid of any disease-producing bacteria.  2 methods are employed for Pasteurization are 1. The Flash method:- milk is brought to 72⁰C and held for not less than 15 sec ( HTST) 2. Holding method:- milk is heated to 63⁰C and held at this temp. for not less than 30 mins.(LTLT)  Another treatment is given called ultra – high treatment at 149.5⁰C for 1 sec.
• 7.
  Pasteurization contd…..  Aspasteurized milk is not sterilized , it must be quickly cooled after pasteurization to prevent multiply of surviving bacteria.  Pasteurization does not produce an objectionable cooked flavour and no important change in nutritive value.
• 8.
  Homogenization  The processof making a stable emulsion of milk fat and milk serum by mechanical treatment and rendering the mixture homogenous.
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  Types of milk Whole milk:- this milk contains at least 3.5per cent of butter fat, which gives it the wholesome taste.  Homogenised milk :- this milk that has been processed so that the cream does not separate and form a layer of the milk.  Sterlised/ ultra heat teatred(UHT):- this is homogenesed milk heated to a high temp. for very short time. This product have shelf life of 6 months without refrigration.  Skimmed milk:- this milk contains very small percentgae of the milk fat but all minerals and proteins of whole milk.
• 10.
  Types contd…..  Buttermilk:- it is a by product of butter making and contains much of the mineral and protien content of the whole milk.  Condensed milk:- it is milk from which a large proportion of the water has been removed. Sugar may be added. It is used in sweet dishes.  Evaporated milk:- it is similar to condensed milk but without added sugar and with more water.  Dried Or Powdered milk:- prepared from skimmed milk, from which most of the water content has been removed