Influence of milk powder on physical and chemical properties of yoghurt made from fresh zebu milk

Abstract

Yoghurt is a nutritious and palatable human food derived from the milk of dairy animals. Quality of yoghurt made from fresh milk is enhanced when solids content of milk is increased. This can be achieved by addition of milk powder to fresh milk for yoghurt production. In this study, milk powder was stirred into fresh milk at 0, 20, 40, 60, 80 and 100 g/L to improve the physico-chemical properties of the yoghurt. Time of curd formation in yoghurt varied from 6–10 hours. Addition of milk powder shortened coagulation time by 2-4 hours. The pH of yoghurt at 3 days of refrigerated storage varied significantly (p<0.05) among the treatments from 4.00–4.40. Yoghurt without milk powder had the highest value and yoghurt with 100 g/L milk powder had the least value. The chemical composition of yoghurt varied significantly (p<0.05) with addition of milk powder. Protein content of yoghurt increased from 3.18 – 4.24%; fat content increased from 4.43 – 5.85%; and total solids increased from 14.50 – 17.52% as level of milk powder in yoghurt milk increased. Sensory scores of yoghurt improved significantly (p<0.05) with incorporation of milk powder into fresh milk prior to fermentation. On a hedonic scale of 1-9, acceptability of the yoghurts were judged as 5.92, 6.80, 6.92, 7.44, 7.66 and 7.71 for 0, 20, 40, 60, 80, and 100 g/L of milk powder inclusion. It may be concluded therefore that, incorporation of milk powder into fresh milk prior to incubation shortened time of curd formation and improved nutritional and sensory qualities of yoghurt made from fresh zebu milk.