Abstract
Milk is a basic food for all age groups, having a very complex chemical compo-sition which differs among species and breeds, It is a perishable commodity which undergoes various deteriorative reactions, peroxidation being the main one. Such a reaction also depends upon the fat globule size of milk from different animals. Hence the composition and size of fat globules in milk have a definite effect and were therefore determined in different species of animals. The study showed signifi-cant variation in size of milk fat globules, maximum being 5.80 in buffalo and minimum 2,96 p. in camel.
I NTRODUCTI ON MATERIALS AND METHODS
Milk has very complex chemical com-position which differs not only among vari-ous species but also within species and even among individuals within that species. Wide variation in the composition of milk seems important in connection with the use of milk in human diet, especially when it furnishes a large part of food intake, as it does for in-fants. Fat globule size in milk also plays an important role in acceptability and keeping quality of milk. It varies with species, breed, stage of lactation and environmental condi-tions(Webb et at, 1974). In dairy industry homogenisation process is carried out to re-duce the fat globule into very small size, so that the taste becomes even and the shelf life of milk may increase by changing the physical structure of fat, It is also important for separation of fat from milk during churning of cream, shipping of milk or cream, and cheese making. The present study was an attempt to investigate the vari-ation in milk composition and milk fat glob-ule size in different species of milk produc-ing animals in Pakistan.
Composite samples of fresh milk of different species of animals such as cow, buffalo, sheep, goat except camel were ob-tained from the Livestock Experiment Station, University of Agriculture, Faisalabad. Composition: Protein was determined by formal titration and specific gravity by using lactometer according to the methods de-scribed by David (1974 Lactose was anal-ysed by Lane and Eynon method as de-scribed by Egan et al. (1984 Fat, SNF, Ash and Moisture were assessed according to A.0A.C. (1984). Fat globule size: The fat globule size was measured by microscopic technique of Cruickshank et al. (1975). A drop of repre-sentative milk sample was put onto well cleaned glass slide and smeared with the help of wireloop. Two drops of methylene blue dye were added onto it, set aside for 2-3 minutes and dried in air. After approxi-mately five minutes the slide was rinsed with distilled water and dried. One drop of oil emulsion was added and the fat globule size was determined under the microscope.
