The effects of nisin (200 and 400 ppm), ε-polylysine (0.1 and 0.2%) and chitosan (0.5 and 1%) in combination with a Mixed Extract (green tea, stinging nettle and olive leaves extracts) on the physicochemical, microbiological characteristics, fatty acid composition and sensory attributes of the nitrite-free frankfurter-type sausages were assessed during 45 days of storage. The results revealed no significant differences on moisture, fat, protein, ash, salt and water activity (aw) among treatments. 1% Chitosan + Mixed Extract sausages displayed the lowest thiobarbituric acid reactive substances (TBARS) and total volatile nitrogen (TVN) values compared to Control after 45 days of refrigerated storage. Combinations of 0.2% ε-Polylysine or 1% Chitosan with Mixed Extract were effective to inhibit total viable count (TVC), yeasts and molds growth. 1% Chitosan preserved the luminosity of sausages during refrigerated storage. However, redness values of 1% Chitosan treatment was lower than those obtained from Control sausages and a significant increase was observed between days 30-45. Total amounts of saturated, monounsaturated and polyunsaturated fatty acids (SFA, MUFA, and PUFA) of frankfurter-type sausages were not largely influenced by the combination of natural antioxidants and antimicrobial compounds. Combinations of 0.2% ε-Polylysine and 1% Chitosan with Mixed Extract were effective to improve the shelf life of nitrite-free frankfurter-type sausages. Therefore, these combinations could be considered as promising nitrite replacer in frankfurter-type sausages.
Keywords: Chitosan; Frankfurter-type sausage; Nisin; Phenolic compounds; Shelf life; ɛ-Polylysine.
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