Microencapsulation of Lactobacillus plantarum NRRL B-1927 with Skim Milk Processed via Ultra-High-Pressure Homogenization

Several health benefits are associated with the consumption of probiotic foods. Lyophilized probiotic cultures are commonly used to manufacture probiotic-containing products. Spray drying (SDR) is a cost-effective process to microencapsulate probiotics. However, the high temperatures of the drying air in SDR can inactivate significant numbers of probiotic cells. Ultra-high-pressure homogenization (UHPH) processing can modify the configuration of proteins found in skim milk which may increase its protective properties as microencapsulating agent towards probiotic cells during SDR. The aim of this study was to evaluate the effect of microencapsulating probiotic Lactobacillus plantarum NRRL B-1927 (LP) with UHPH-treated skim milk after SDR or freeze drying (FD). Dispersions containing LP were made with either UHPH-treated (at 150 MPa or 300 MPa) or untreated skim milk and dried via concurrent SDR (CCSD), mixed-flow SDR (MXSD) or FD. Higher cell survival (%) of LP was found in powders microencapsulated with 150 MPa-treated skim milk than in those microencapsulated with non-UHPH-treated and 300 MPa-treated skim milk via FD followed by MXSD and CCSD, respectively. Increasing UHPH pressures increased the particle size of powders produced via CCSD; and reduced particle agglomeration of powders produced via MXSD and FD. This study demonstrated that UHPH processes improves the effectiveness of skim milk as a microencapsulating agent for LP, creating powders that could be used in probiotic foods.