Optimization of the inlet temperature during spray drying increases the productivity and quality of kefir powder

Abstract

This study aimed to optimize the inlet temperature for the spray drying process to increase productivity, improve physicochemical quality, and maintain the viability of microorganisms in the kefir products. Kefir was powdered using a laboratory-scale spray dryer at inlet temperatures of 120 °C, 140 °C, 160 °C, and 180 °C, coupled with a feed pump rate to maintain the desired outlet temperature between 66 and 68 °C. The outlet temperature was obtained by increasing the pump rate at higher inlet temperatures and controlling atomization pressure and aspirator pressure. The physicochemical quality and microbial viability at different inlet temperatures and processing times, and the yield of dried kefir were observed. The results revealed that an inlet temperature of 160 °C showed the most effective drying condition. This inlet temperature recorded a faster process rate (19.35 ml/min) with decreased residence time (20.67±0.94 min) while maintaining high bacterial viability (8.75 log CFU/g) and protein content (15.14±0.28%) in the products. The inlet temperature of 160 °C has an impact on high productivity, while the outlet temperature of 66 – 68 ℃ maintains physicochemical quality and microbial viability. These spray-drying parameters can be applied in commercial kefir production to produce marketable products with better manufacturing efficiency.