Exploration of the mechanism of key odour substances in porcine large intestine by enzyme-alkali-alcohol ternary composite treatment: Efficacy of deodorisation treatments and impact on quality.

In this study, the key off-odour compounds in porcine large intestine were identified using headspace solid-phase microextraction coupled with gas chromatography-mass spectrometry (HS-SPME-GC-MS), through which thirty volatile compounds were detected, and a combined deodorisation process was subsequently developed. Odour activity value (OAV) analysis revealed eight key off-odour substances (OAV ≥ 1), whereas gas chromatography-olfactometry-mass spectrometry (GC-O-MS) further confirmed that 4-methylphenol, indole and 3-methylindole were the predominant contributors to the characteristic faecal and animal odours. In single-factor experiments, the deodorisation effects of ethanol, sodium hydroxide and papain were evaluated, and an optimal combined process was established, consisting of 1.2% papain (45 min), 1.2 g/L NaOH (30 min) and 35% ethanol (45 min). This combined treatment synergistically reduced the total content of the key off-odour compounds by 82.60%, markedly outperforming each individual method. Moreover, it improved the quality of the final product, as evidenced by reduced hardness and chewiness, and a 28.04% decrease in cooking loss. Collectively, these findings provide a scientific basis for quality enhancement by elucidating the key odour sources and the underlying deodorisation mechanisms.