CHEMISTRY OF MILK

Module 1. Milk definition, composition and variation

Lesson 1
DEFINITION OF MILK AS PER FOOD STANDARDS AND SAFETY AUTHORITY OF INDIA, 2006 (FORMERLY PREVENTION OF FOOD ADULTERATION OF INDIA)

1.1 Introduction

Milk is a complex fluid containing many components in different states of dispersion. Understanding its properties and the changes that occur in it requires knowledge of all the components and their interaction with other constituents. An over view of the milk composition and their physical states of dispersion are being dealt in this lesson.

1.2 Milk Definition

Milk in legal terms (PFA1954) may be defined as whole, fresh,clean, lacteal secretions, obtained by complete milking of one or more healthy milch animals, excluding that obtained 15 days before or 5 days after or such periods as may be necessary to render the milk practically colostrum free and containing legally prescribed minimum percentage of fat and Solids-not-fat (SNF).

However in chemical terms milk may be defined as a complex chemical substance in which fat is present in the form of an emulsion, protein and some mineral matter in the colloidal state and lactose with some minerals and soluble proteins in the form of true solution.

All species of mammals secrete milk to provide nutrients required for the optimum growth of the new born,apart from protecting it from some of the common diseases. The development of the young one in all species of mammals is not uniform as such the composition of the milk secreted by these mammals will also vary depending up on the nutritional needs of the young one. It is a matter of academic interest to know the average composition of milk from some of the species along with the composition of milk from human. The scientific names of the mammals is given here

Table 1.1 Scientific names for some species of mammals



Table 1.2 Approximate composition of cow milk (western)

1.3 Differences in the Composition of Milk from Various Species

The Table 1.3 showing the composition of milk from various species is given for understanding the variation in the composition of the milk secreted by them. It could be observed that the buffalo milk is having the maximum fat while the fat content in sheep milk is also much close to that. Similarly the fat percent in goat milk is much similar to cow milk. Variation among the protein percent is also very less among these species. The lactose content in Human milk is characterized by having higher percent of lactose and fat while the protein and ash content is much less when compared with other species. The energy supplied through the milk is highest in buffalo and sheep while the difference is very much less between the milk from the remaining species

Table 1.3 Composition of milk from different animal species

1.4 Legal Standards for Various Classes of Milk

According to the FSSAI (2006) the standards for different classes and designations of milk in India are presented in Table 1.4.

Table 1.4 Legal standards for various classes of milk

(FSSAI, 2006)