Changes in physicochemical properties and water-soluble small molecular compounds of dry-cured Xuanwei ham during processing

Thirty experimental Xuanwei hams were processed by a traditional method using green hams from local Xuanhe pigs of Xuanwei, Yunnan province, PR China. Samples of Biceps femoris were collected from six hams randomly at the five key processing stages, that is green ham, salting, air drying, aging for 3 months, and aging for 7 months. Physicochemical properties and water-soluble small molecular (WSSM) compounds change during the processing period of Xuanwei ham were evaluated. Moisture contents, water activity, and total nitrogen contents (TN) decreased significantly (p < .05). On the contrary, chloride content, weight loss rate, non-protein nitrogen content (NPN), and the protein hydrolysis index (P.I.) were observed a significant increase during the processing. The WSSM compounds in various processing stages of Xuanwei ham were analyzed by proton nuclear magnetic resonance (H-1-NMR) technology. A total of 54 WSSM compounds were found, consisting of 26 amino acids and their derivatives, 10 organic acids, 6 nucleic acids, 4 amines and ammonia compounds, 3 alcohols, 2 sugars, and 3 other WSSM compounds. After aging for 7 months, the content of free amino acids in hams reached 58.93 mg/g, and the main amino acids were glutamic acid and alanine. In this study, the physicochemical properties of Xuanwei ham were evaluated effectively, which provided the basis for the quality control of Xuanwei ham. Practical applications Dry-cured Xuanwei ham is a traditional fermented meat product in Yunnan province of southwest China. The aim of this study was to determine the changes in physicochemical properties and water-soluble low molecular weight compounds of dry-cured Xuanwei ham during the production process. Our findings thus provide a theoretical analysis on the quality changes of dry-cured Chinese Xuanwei ham during processing. The results of this study can provide important theoretical basis for further study on protein degradation mechanism and characteristic flavor formation of Xuanwei ham.