Rakesh Kumar Raigar, Said Prashant Pandharinath and Indrajit Dalai
College of Agricultural Engineering and Post Harvest Technology, CAI-I, Ranipool, Gangtok, Sikkim
Yak (Bos grunniens) is a source of livelihood for the community living in Himalayas of Sikkim at 4,000–6,500 meters above mean sea level. Yaks are reared since ages for milk and milk products, transportation, dung for fuel, and hides for housing, essential for rural population residing in high altitudes in Sikkim. Different value-added products are being traditionally manufacture by farmers at cottage scale from the yak milk, the most common being the hard cheese (Churpi). The cottage cheese is more popular in high altitude places. The major unit operation is involved in the process such as filtration, separation, boiling, coagulation, pressing, cutting, drying, and packaging. The yak milk cottage cheese (hard churpi) is having moisture content from 8-10%, protein 60-65% and carbohydrate. The Yak milk churpi is the key source of enhance the income of high-altitude places. In this study, after drying yak milk churpi samples in the ranges of 50–70 °C inlet air temperature and 0.6 and 1.7 m/s air velocity in a laboratory-scale cabinet dryer, the quality characteristics, including moisture content, pH, titrable acidity, hardness, colour, antioxidant, and total phenol content, were measured. The responses were significantly (p ≤ 0.05) influenced by the temperature and velocity of the drying method. The higher temperature and higher velocity have opened the surface of the churpi sample and reduced the whiteness of the sample. The results of the study showed that the drying process at 50°C at 1.7 m/s was the optimal condition with the least time and the highest rate of drying. In addition, SEM was used for the optimised samples to express the microstructure of the churpi after drying.