The fate of spore-forming bacteria throughout the gelatin processing

Abstract

Gelatin is a natural protein soluble in water and extracted from animal collagen through thermal and chemical treatments. Its physicochemical properties make it valuable for various applications in the food and pharmaceutical industries. Ensuring its microbiological quality is essential for maintaining its properties and ensuring the safety of products that use it as a raw material. This study analyzed the concentrations of four groups of spore-forming microorganisms (aerobic mesophiles, presumptive Bacillus cereus, aerobic thermophiles, and anaerobic mesophiles) throughout all stages of gelatin processing at three seasons of the year (spring, summer, autumn). A total of 600 samples were collected from a single plant located in São Paulo, Brazil. The isolated microorganisms were identified through 16S rRNA gene sequencing. Significant differences in the concentrations of spores of these groups were observed and analyzed using ANOVA and PLS-DA methods. The highest log-reductions of spores were observed as follows: aerobic mesophiles showed a log-reduction of γ = $-$1.9 from the extrusion to the final product; B. cereus showed a log-reduction of γ = $-$1.9 from the raw material to the pre-washing; aerobic thermophiles had a log-reduction of γ = $-$1.6 from the raw material to the pre-washing; and anaerobic mesophiles had a log-reduction of γ = $-$1.1 from the concentrated tank to the sterilization. Sequencing identified B. cereus group members, B. licheniformis, Geobacillus sp., Clostridium sp., Lysinibacillus sp., and Brevibacillus sp. These findings are significant for industry, as some of these microorganisms produce toxins harmful to humans and contribute to product deterioration through the production of gelatinases.