NMR-based metabolomics profiling of no-added-nitrite Chinese bacon (unsmoked) during processing

Variations in the taste quality of no-added-nitrite Chinese bacon (unsmoked) during processing were investigated using ¹ H-NMR and multivariate data analysis. The results showed that 21 metabolites were dominant during processing, which involved marinating, air-drying, fermentation, and baking, including amino acids, sugars, organic acids, nucleic acids and their derivatives, and alkaloids. The contents of isoleucine, leucine, valine, alanine, acetate, glutamate, succinate, glycine, sucrose, tyrosine, and phenylalanine increased continuously throughout the process. The lactate, creatine, carnosine, betaine, taurine, hypoxanthine, and AMP contents all significantly increased after baking; the inosine content significantly increased after fermentation and then decreased; the histamine content significantly increased after air-drying and then decreased; and the histidine content decreased. Each processing treatment promoted taste formation in no-added-nitrite Chinese bacon (unsmoked), especially baking. The baking point owned relatively higher levels of metabolites and sensory evaluation compared to other treatments. Sensory evaluation revealed that the ultimate taste of Chinese bacon (unsmoked) at the end of baking tended toward umami (glutamate), sweetness (AMP), and sourness (lactate). The first and second principal components explained 74.0% and 13.4% of the variables, respectively. These findings indicated the potential of NMR-based metabolomics for assessing the taste quality of no-added-nitrite Chinese bacon (unsmoked), which could contribute to a better understanding of taste compound changes in meat products. PRACTICAL APPLICATION: Nitrite is commonly used in Chinese bacon (unsmoked), but excessive intake is not good for human health. Nitrite has been replaced with nitrite substitutes to prepare no-added-nitrite Chinese bacon (unsmoked). The metabolites of no-added-nitrite Chinese bacon (unsmoked) were detected to determine the key treatment that contributes to the formation of taste during processing. This study determined the main taste components of no-added-nitrite Chinese bacon (unsmoked) and its formation process, which provides new insight into the production and characteristics of flavor in Chinese bacon (unsmoked).