Effect of Different Air Oven Temperatures on Chemical, Physical, and Microbial Properties of Dried Bio-Yoghurt Product

The aim of this study was to compare the physical, chemical, and microbiological features of bio-yoghurt that had been air-oven-dried at three temperatures (40, 50, and 60 ◦C) to those of fresh bio-yoghurt. The results showed that drying bio-yoghurt at 40–60 ◦C decreased the number of probiotic starter bacteria in dried yoghurt products compared to fresh bio-yoghurt. The dried yoghurt’s moisture, protein, fat, carbohydrate, and ash contents were 4.16–4.55%, 38.22–40.02%, 1.33–1.43%, 47.94–49.45%, and 6.37–6.55%, respectively. The pH and total acidity levels of dried yoghurt were within acceptable ranges at various temperatures and storage durations. At dif- ferent temperatures, the viscosity values of the products decreased by 620–550 cp; however, the hygroscopicity values remained constant. During a 90-day storage period, the dried yoghurt prod- uct’s physical, chemical, and microbiological characteristics remained within acceptable levels. Using a drying temperature of 40–50 ◦C kept the number of live bacteria below acceptable ranges during storage periods. Lactobacillus acidophilus counts were 6.75 and 6.70 log CFU/g, respectively, whereas Bifidobacterium bifidum numbers were 6.66 and 6.08 log CFU/g, respectively. In conclusion, drying bio-yoghurt in an air oven at 40–50 ◦C provided a dried product with a high number of viable probiotic bacteria and satisfactory physicochemical characteristics after 3 months.