Novel combinations of chitosan, carnocin and sulphite for the preservation of chilled pork sausages

The aim of this study was to develop novel preservation systems for fresh pork sausages based on combinations of chitosan (polymeric β-1,4-N-acetylglucosamine) carnocin (a bacteriocin produced by Carnobacterium piscicola) and low concentrations of sulphite. Two pilot-scale trials showed that 0.6% chitosan combined with low sulphite (170 ppm) retarded the growth of spoilage organisms more effectively (3–4 log cfu/g) than high levels (340 ppm) of sulphite alone at 4 °C for up to 24 days. Microbial counts for frozen sausages showed that the preservative efficacy of the chitosan/sulphite combination was maintained following frozen storage. Carnocin did not protect sausages from spoilage but in a challenge trial, it reduced the numbers of Listeria innocua by up to 2.0 log cfu/g in the first 5 days of chill-storage. Sulphite was degraded rapidly within the first 3 days of storage in all the sausages that contained only this preservative but levels decreased less rapidly and persisted for longer in the presence of chitosan. Results of Quantitative Descriptive Analysis using 31 trained panellists reflected the gradual deterioration of all the sausages during storage. The batch containing chitosan and sulphite deteriorated less rapidly and was judged to be more acceptable for a longer period than all the other batches.