Soy Protein Improves the Shelf Life of a Spray-Dried Probiotic for Poultry

Abstract

Spray drying is a cost-effective, scalable, and efficient method for encapsulating probiotics such as Ligilactobacillus salivarius CRL 2217. However, the elevated temperatures involved in this process can notably reduce bacterial viability. The combination of soy protein and carbohydrates in the encapsulating matrix may form a protective barrier around bacteria, potentially mitigating this adverse effect. This study aimed to evaluate various matrices containing soy protein isolate for encapsulating Lg. salivarius CRL 2217 via spray drying, and identify combinations that maintain viability over 12 months of storage at different temperatures. Additionally, the study investigated the effect of excipients on the maintenance of low water activity in the powders. Lg. salivarius CRL 2217 was spray-dried with different soy protein isolate matrices and stored at −18, 5, and 25 °C for 12 months. The microcapsule structure, innocuity, retention of the probiotic properties of the strain, and viability during storage were analysed. The results demonstrated innocuous spherical particles without surface cracks and with unaltered surface properties of the probiotic strain. Response surface methodology predicted a viability loss of less than 1 log CFU/g when storing powders with the highest soy protein isolate concentration between −18 and 6 °C for 12 months. This study is the first to evaluate the shelf life of spray-dried probiotic bacteria with soy protein isolate over a year at various temperatures, demonstrating high viability retention.