Effect of lactic acid addition on physicochemical properties and microbial community dynamics during low-salt shrimp paste fermentation

This study evaluated the effects of lactic acid on the physicochemical properties and bacterial community of low-salt shrimp paste fermentation. Parameters, including pH, amino acid nitrogen (AAN), free amino acids, total protein, malondialdehyde (MDA), and biogenic amines (BAs), were monitored. AAN and free amino acid contents increased in all samples, accompanied by a decrease in total protein, indicating ongoing proteolysis. During fermentation, the paste with lactic acid exhibited a lower pH (6.26 to 8.50) and significantly lower levels of MDA and total BAs in comparison to the control paste. This suggests a reduced lipid oxidation and improved safety. High-throughput sequencing revealed that <i>Staphylococcaceae</i> and <i>Staphylococcus</i> were the predominant family and genus, respectively, after 8 days of fermentation of paste with lactic acid. <i>Staphylococcus</i> abundance positively correlated with pH and AAN levels. These findings highlight lactic acid's potential to modulate microbiota and improve product quality and safety.