Effect of sub-lethal heat stress on viability of Lacticaseibacillus casei N in spray-dried powders

The potential of thermal adaptation enabling a probiotic Lacticaseibacillus casei N (N) to withstand heat stress and spray drying was investigated. Among the encapsulating agents used (maltodextrin, corn starch (CS), and acacia gum) for lactobacillus, CS had shown the highest survivability of 95.6% after spray drying. Further, the slurry prepared using L. casei (N), and CS as carrier material was subjected to sub-lethal heat stress at 45 and 50 degrees C for 60 min before spray drying. After spray drying, survivability was increased by 0.26 and 0.19 log in N + CS 45 and N + CS 50, respectively, compared to a control that was not treated to sub-lethal stress (N + CS). During storage studies for 90 days, the sub-lethal heat-stressed probiotic powders had shown better survivability at 4 degrees C. The survivability of L. casei (N) in spray-dried powders in simulated gastric fluid revealed that N + CS 45 had 3.06 log cycles higher survivability than N + CS. The SDS PAGE and FTIR analysis of intracellular proteins of heat-stressed L. casei (N) cells revealed overexpression of heat shock proteins indicating a change in protein structure. The study suggests that the sub-lethal heat stress before spray drying increases the viability of probiotic cultures, which have potential food applications.

Automated summary

The study found that sub-lethal heat stress before spray drying increases the viability and adaptation of probiotic cultures. Corn starch is an ideal encapsulating agent that can maximize the protection of probiotics. Probiotic powders subjected to heat stress show better survivability during storage.