Abstract
Porcine small intestine (PSI) develops a specific offensive odor after storage for only 0.5 to 1 day at 20°C, and bacterial counts increase exponentially during this storage period. Pretreatment at 500 MPa for 10 min at 20°C was found to drastically reduce microbial counts and maintain PSI freshly for at least 1 day after the treatment in terms of microbial counts, amounts of volatiles, and organoleptic features. Anaerobic storage of PSI was unable to inhibit offensive odor development, but gave a gas chromatographic pattern similar to that observed when PSI was stored under control storage conditions. Some chemicals, including those listed as legal food additives, retarded the evolution of the offensive odor and bacterial growth. However, these chemicals, added at levels below the legally permitted limits, were unable to effectively suppress development of the offensive odor. In storage experiments, the amount of methyl mercaptan (MM), the main volatile responsible for the offensive odor, was found to correlate significantly with the count of anaerobic bacteria. Furthermore, inoculation of anaerobes, among the various microbial groups separated from PSI, onto fresh PSI that had been pasteurized by high-pressure pretreatment led to development of the same, typical offensive odor (MM) as that produced by control PSI after storage. These results indicate that evolution of the offensive odor of PSI during storage is mostiy, if not completely, attributable to the growth of anaerobes.
