Changes of volatiles in soy sauce‐stewed pork during cold storage and reheating

Pork, soy sauce, and pork in soy sauce were cooked separately for 4 h; their volatiles were isolated, analysed and compared. Many of the volatiles reported to be present in pork or soy sauce were lost, and some volatiles identified in this research were generated from precursors in pork and soy sauce during cooking. Water‐boiled pork and soy sauce‐stewed pork were prepared and stored at 4 °C; they were reheated daily and stored again at 4 °C for 10 days. During storage the amount of compounds containing sulphur, such as dimethyl trisulphide and thialdine, was higher in the water‐boiled pork than in the soy sauce‐stewed pork. 3,5‐Dimethyl‐ trans ‐1,2,4‐trithiolane was found only in the soy sauce‐stewed pork. Significantly more aldehydes produced from lipid oxidation, such as hexanal, 2,4‐decadienal and 2‐undecenal, were present in the water‐boiled pork than in the soy sauce‐stewed pork during storage. These aldehydes reached a maximum quantity at day 6 of storage. In contrast, the soy sauce‐stewed pork contained more hexadecanal, octadecanal and 9‐octadecenal than the water‐boiled pork.