Technological variables influencing the growth and stability of a silage inoculant based on spray‐dried lactic acid bacteria

Abstract

Aims: To investigate the influence of different culture media and fermentation conditions on growth performance and viability of three lactic acid bacteria (LAB) strains with potential as silage inoculants, and to optimize spray‐drying in order to enhance survival to dehydration and storage stability. Methods and Results: In house‐formulated MRS was a suitable low‐cost culture medium for Lactobacillus plantarum Hv75, Pediococcus acidilactici 3903 and L. buchneri B463. Uncontrolled pH biomass production conferred enhanced stability during storage at 4 °C after spray drying. The use of whey protein concentrate 35 (WPC)‐maltodextrin (M) as matrix, inlet temperature of 145‐150 °C and air flow rate of 601 l h−1 was adequate for the production of dehydrated LAB. According to the desirability function, at this optimized condition, moisture content, yield and solubility were predicted to be 3.96%, 73.68%, and 90.36% respectively. Those conditions also showed a decrease of 0.855 log CFU g‐1 after drying, no loss in viability at 4 °C for 6 months and 1 log CFU g‐1 reduction at 25 °C. Conclusions: Stable and economically feasible dehydrated LAB cultures were obtained by using alternative culture media, fermentation under uncontrolled pH, and optimizing spray‐drying process conditions through the desirability function method.