Microbiological, physical, and sensory characteristics of marinated chicken drumsticks treated with nisin, thermal treatment, tumbling and the lactoperoxidase system

Currently meat marination is practiced to improve product's physical and sensory attributes, and usually not intended to improve the microbial quality of the product. Nisin, which is a natural, nontoxic, and heat stable polypeptide produced by Lactococcus lactis, has been shown to inhibit many microorganisms, and has been approved for use in some dairy products. Thermal treatment has been widely applied to control the growth of microorganisms in the food industry for years. Tumbling, which helps the distribution of marinade solution during processing should enhance the action of antimicrobial agents. The lactoperoxidase system (LPS) consists of lactoperoxidase (LP), thiocyanate (SCN−), and hydrogen peroxide (H ₂O₂), is an inhibitory system that is present naturally in bovine milk, and had been showed to be inhibitory against some microorganisms. Limited information on the contribution of marination, nisin, thermal treatment, tumbling, and the lactoperoxidase system to the microbial quality of treated poultry products is available.; In the first part of the dissertation, four studies (experiments 1 to 4) focused on the microbial quality of the treated samples. The results showed that the combinations of nisin plus thermal treatment, nisin plus tumbling, nisin plus LPS, and LPS plus thermal treatment resulted in lower total microbial and psychrotrophs counts of the treated samples compared with the control samples during the 7 days of refrigerated storage at 4°C. Depending on the combinations of treatment, some interactions among treatments existed. Further studies were conducted to evaluate whether these combined treatments had any influence on the physical and sensory characteristics of the treated samples. In the second part of the dissertation, four studies (experiment 5 to 8) focused on the physical and sensory qualities of the treated samples. The results showed that the combinations of treatments did not impair most of the physical or sensory qualities of the treated samples. In conclusion, based on the microbial, physical and sensory qualities, marinated chicken drumsticks treated with the combinations of nisin plus thermal treatment, nisin plus tumbling, nisin plus LPS, or LPS plus thermal treatment were acceptable.