The Effect of the Ultra-High-Pressure Homogenization of Protein Encapsulants on the Survivability of Probiotic Cultures after Spray Drying

Interest in probiotic foods and ingredients is increasing as consumers become more aware of their potential health benefits. The production of these products often involves the use of dry culture powders, and the techniques used to produce such powders often suffer from significant losses of viable cells during drying or require the use of expensive drying technologies with limited throughput (e.g., freeze drying). In this study, the authors examined whether culture survivability during spray drying could be increased via the treatment of two common protein encapsulants with ultra-high-pressure homogenization (UHPH). Lactobacillus plantarum NRRL B-1927 (also known as ATCC 10241), a probiotic strain, was suspended in either soy protein isolate (SPI) or whey protein isolate (WPI) which had been either treated with UHPH at 150 Mpa or left untreated as a control. The suspensions were then dried using either concurrent-flow spray drying (CCSD), mixed-flow spray drying (MFSD) or freeze drying (FD) and evaluated for cell survivability, particle size, moisture content and water activity. In all cases, UHPH resulted in equal or greater survivability among spray dried cultures, showed reductions in particle size measures and, except for one marginal case (CCFD SPI), significantly reduced the moisture content of the dried powders. The combination of these findings strongly suggests that UHPH could allow probiotic powder manufacturers to replace freeze drying with spray drying while maintaining or increasing product quality.