title: Assessment of Clostridium perfringens spore response to high hydrostatic pressure and heat with nisin.
abstract: The elimination of spores from low-acid foods presents food-processing and food-safety challenges to high-pressure processing (HPP) developers as bacterial spores are extremely resistant to pressure. Therefore, the effects of pressure (400-800 MPa), temperature (35-95 °C), and nisin (0-496 IU/mL) on the inactivation of Clostridium perfringens AS 64701 spores at various pressure-holding times (7.5-17.5 min) were explored. A second-order polynomal equation for HPP- and nisin-induced inactivation of C. perfringens spores was constructed with response surface methodology. Experiment results showed that the experimental values were shown to be significantly in agreement with the predicted values because the adjusted determination coefficient (R (Adj)²) was 0.9708 and the level of significance was P < 0.0001. The optimum process parameters (obtained by solving the quadratic polynomal equation) for a six-log cycle reduction of C. perfringens AS 64701 spores were pressure of 654 Mpa, temperature of 74 °C, pressure-holding time of 13.6 min, and nisin concentration of 328 IU/mL. The validation of the model equation for predicting the optimum response values was verified effectively by ten test points that were not used in the establishment of the model. Compared with conventional HPP techniques, the main process advantages of HPP-nisin combination sterilization in the UHT milk are, lower pressure, temperature, natural preservative (nisin), and in a shorter treatment time. The synergistic inactivation of bacteria by HPP-nisin combination is a promising and natural method to increase the efficiency and safety of high-pressure pasteurization.
authors.affiliation: College of Food Science and Engineering, Nanjing University of Finance and Economics, No. 128, Railway North-Street, Nanjing 210003, Jiangsu Province, People's Republic of China. gaoyl6@yahoo.com.cn
authors.forename: Yulong
authors.initials: Y
authors.lastname: Gao
authors.forename: Weifen
authors.initials: W
authors.lastname: Qiu
authors.forename: Ding
authors.initials: D
authors.lastname: Wu
authors.forename: Qiang
authors.initials: Q
authors.lastname: Fu
mesh_terms: D000465:Algorithms; D000818:Animals; D000900:Anti-Bacterial Agents / Q000494:pharmacology; D003016:Clostridium perfringens / Q000187:drug effects / Q000254:growth & development; D015169:Colony Count, Microbial; D003257:Consumer Product Safety; D005516:Food Microbiology; D005519:Food Preservation / Q000379:methods*; D006358:Hot Temperature; D008892:Milk / Q000382:microbiology*; D015233:Models, Statistical; D009561:Nisin / Q000494:pharmacology*; D011312:Pressure; D013171:Spores, Bacterial / Q000187:drug effects / Q000254:growth & development
chemical_list: D000900:Anti-Bacterial Agents; D009561:Nisin