Effects of Fermentation on Off-Odour Reduction and Flavour Compounds in Pig Large Intestines.

Pig large intestines (PLIs) are usually processed into various dishes for consumption through cooking methods such as stir frying, stewing, and braising, which are difficult for many consumers to accept because of their unique and pungent off-odours. To reduce the number of off-odour substances present in PLIs, we compared the effects of an untreated control group (blank), added flour (WF), and added mixed 4% flour in PLIs for fermentation (SC) on the treatment of PLIs. We analysed colour, thiobarbituric acid reactive substance (TBARS) values, and total volatile basic nitrogen (TVB-N) values; additionally, sensory evaluations were performed. The results showed that after 5 h of fermentation, the mixed flour exhibited the most significant effect on reducing the off-odour of PLIs, exhibited the least effect on the TBARS value and TVB-N was controlled within a reasonable range, while simultaneously maintaining good quality. A total of 415 volatile compounds were identified via flavouromics. Combined with principal component analysis (PCA) and orthogonal partial least squares discriminant analysis (OPLS-DA), the key off-odour substances, including indole (faecal odour), 2-pentylthiophene (fat odour), (E)-2-octenal (fishy odour), and 2-methoxy-phenol (smoky odour), were reduced by 28.1%, 23.90%, 21%, and 22.89%, respectively, after fermentation. Moreover, the content of ethyl octanoate increased 31.04-fold, which enriched the flavour components of the PLIs. The results showed that fermentation of mixed flour could be used as a method to reduce the off-odours of PLIs.