No abstract

To deepen the understanding of the effect of potassium lactate on the taste of Rugao ham, proteolysis index, enzyme activities and protein degradation of Rugao ham salted with potassium lactate (0%, 0.5%, 1%, 2%) were investigated. Metabolites of Rugao ham were identified by 1H nuclear magnetic resonance (NMR) spectroscopy and the metabolic pathways of the key metabolites were enriched by the Kyoto Encyclopedia of Genes and Genomes (KEGG); the relationship between taste and metabolites was assessed by partial least square discriminant analysis (PLS-DA). The hams with 2% potassium lactate showed lower cathepsin B and L activities, and higher aminopeptidase activities than that of the control group. The contents of free amino acids and organic acids significantly increased from the control to the treatment of 2% potassium lactate. PLS-DA further demonstrated that aspartate, glutamate, alanine, serine, threonine, acetate, lactate, succinate, carnosine, β-glucose and glycerol were the key metabolites to improve the taste of Rugao ham in the treatment of 2% potassium lactate. Metabolic pathways analysis further demonstrated that amino acids metabolism was the main pathway for the taste development of Rugao ham.

To deepen the understanding in the effect of potassium lactate on the sensory quality and safety of Rugao ham, sensory attributes, physicochemical parameters, total volatile basic nitrogen (TVBN), microorganism community and biogenic amines of Rugao ham manufactured with different potassium lactate levels (0%, 0.5%, 1%, 2%) were investigated; the relationship between microbial community and the formation of TVBN and biogenic amines was further evaluated. With the increase of potassium lactate from 0% to 2%, the increased sensory scores and the decreased total aerobic bacterial count and TVBN were observed; the abundance of Staphylococcus increased, while the content of Halomonas decreased. LDA effect size (LEfSe) and correlations analysis showed that Staphylococcus equorum and Lactobacillus fermentum could be the key species to improve sensory scores and decrease biogenic amines and TVBN. Metabolic pathway analysis further showed that amino acids metabolism and nitrogen metabolism were mainly involved in decreasing TVBN and biogenic amines in the treatment of 2% potassium lactate.