Optimization of heat and relative humidity conditions to reduce Escherichia coli O157:H7 contamination and maximize the germination of radish seeds. (June 2016)

• Record Type: Journal Article
• Authors: Song, M.K.; Kim, H.W.; Rhee, M.S.
• Is Part Of: Food microbiology. Volume 56(2016:Jun.)
• Page Start: 14
• Page End: 20
• Publication Date: 2016-06
• Subjects: Response surface methodology -- Desirability function -- Heat and relative humidity -- Seed decontamination -- Optimization; Food Microbiology -- Periodicals; Aliments -- Microbiologie -- Périodiques; Food -- Microbiology; Periodicals; Food -- Microbiology -- Periodicals; Food contamination -- Periodicals; 664.001579
• DOI: 10.1016/j.fm.2015.12.001
• Languages: English
• ISSNs: 0740-0020

Abstract

Abstract: We previously reported that a combination of heat and relative humidity (RH) had a marked bactericidal effect on Escherichia coli O157:H7 on radish seeds. Here, response surface methodology with a Box-Behnken design was used to build a model to predict reductions in E. coli O157:H7 populations based on three independent variables: heating temperature (55 °C, 60 °C, or 65 °C), RH (40%, 60%, and 80%), and holding time (8, 15, or 22 h). Optimum treatment conditions were selected using a desirability function. The predictive model for microbial reduction had a high regression coefficient (R 2 = 0.97), and the accuracy of the model was verified using validation data (R 2 = 0.95). Among the three variables examined, heating temperature ( P < 0.0001) and RH ( P = 0.004) were the most significant in terms of bacterial reduction and seed germination, respectively. The optimum conditions for microbial reduction (6.6 log reduction) determined by ridge analysis were as follows: 64.5 °C and 63.2% RH for 17.7 h. However, when both microbial reduction and germination rate were taken into consideration, the desirability function yielded optimal conditions of 65 °C and 40% RH for 8 h (6.6 log reduction in the bacterial population; 94.4% of seeds germinated). This study provides comprehensive data that improve our understanding of the effects of heating temperature, RH, and holding time on the E. coli O157:H7 population on radish seeds. Radish seeds can be exposed to these conditions before sprouting, which greatly increases the microbiological safety of the products. Highlights: Combined use of heat and relative humidity (RH) inactivated pathogens on the seeds. Response surface methodology was used to establish a predictive model (R 2 = 0.97). The optimum conditions were 65 °C, 40% RH, for 8 h (6.6 log reduction). The model and optimized conditions will be of practical use to the sprout industry.