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Antimicrobial activity of collagen casing impregnated with nisin against foodborne microorganisms associated with ready-to-eat sausage

Batpho, Kasirin, Boonsupthip, Waraporn, Rachtanapun, Chitsiri
Food control 2017 v.73 pp. 1342-1352
Fourier transform infrared spectroscopy, Lactobacillus plantarum, Listeria monocytogenes, Staphylococcus aureus, agar, anti-infective properties, bacteria, cell viability, collagen, color, food pathogens, food safety, minimum inhibitory concentration, nisin, ready-to-eat foods, sausages, shelf life, spoilage bacteria, tensile strength
Antimicrobial collagen casing incorporated with nisin was developed to inhibit foodborne pathogens and spoilage bacteria associated with ready-to-eat (RTE) sausage. Collagen casing was impregnated with 10,000 ppm of nisin solution at vacuum pressure (-680 mmHg) under various conditions of a vacuum time range from 150 to 600 s and an atmospheric time range from 30 to 90 s. The antimicrobial activity of the collagen casing impregnated with nisin was screened using the survival cell count method against Listeria monocytogenes strain Scott A. After that, the most active antimicrobial casing was examined both in vitro and in Vienna sausage. In vitro, the antimicrobial casing decreased L. monocytogenes by 2.8 log CFU/mL, Staphylococcus aureus by 2.1 log CFU/mL and Lactobacillus plantarum by 2.4 log CFU/mL (>99% reduction) when compared with a pre-treated collagen casing (CTRL). After applied to the sausage, the antimicrobial casing extended shelf-life of the sausage at least 90 days at 4 °C and 49 days at 10 °C, respectively. Furthermore, it reduced artificially inoculated L. monocytogenes by 1.1 log CFU/g (>90% reduction) during storage at 4 °C. The concentration of nisin released from the casing was evaluated using the agar well diffusion method. An amount of 852 ppm nisin was released from the antimicrobial casing which was higher than the minimum inhibitory concentration (MIC) values of tested bacteria (25–250 ppm). The FTIR spectral band of the antimicrobial casing showed interaction between nisin and collagen casing at 1800-800 cm−1. Furthermore, physical properties of the antimicrobial casing and CTRL were not significantly different in color, thickness and percent elongation (%E) but the tensile strength of IMP was higher than CTRL. Therefore, it can be concluded that the antimicrobial collagen casing impregnated with nisin has the potential to control foodborne microorganisms in order to enhance the microbial food safety and shelf life of RTE sausage.