Antimicrobial potential of cauliflower, broccoli, and okara byproducts against foodborne bacteria

The antimicrobial potential of cauliflower, broccoli, and okara byproducts was assessed against Gram-positive and Gram-negative bacteria. Salmonella enterica serovar Typhimurium, Escherichia coli O157:H7, Bacillus cereus, and Listeria monocytogenes serovar 4b growth behavior was assessed under exposure to 5% vegetable byproducts added to the reference medium, buffered peptone water (0.1% [wt/vol]), at 37°C. Although the byproducts were not effective against L. monocytogenes, they were bactericidal against Salmonella Typhimurium, E. coli O157:H7, and B. cereus. The most promising results were achieved with the cauliflower-Salmonella Typhimurium combination, because the bacterial population was reduced by 3.11 log10 cycles after 10 h of incubation at 37°C as a result of 5% cauliflower addition. Further studies were carried out for this combination, at different cauliflower concentrations (0, 0.5, 1, 5, 10, and 15%) and at temperatures in the range of 5-37°C. The greatest inactivation level (6.11 log10 cycles) was achieved at refrigeration temperature (5°C) using 15% cauliflower addition. Both temperature and cauliflower concentration significantly (p≤0.05) influenced the Salmonella Typhimurium inactivation level. The kinetic parameters were adjusted to mathematical models. The modified Gompertz mathematical model provided an accurate fit (root-mean-square error (RMSE) [0.00009-0.21] and adjusted-R(2) [0.81-0.99]) to experimental Salmonella Typhimurium survival curves describing inactivation kinetics of the pathogen to the antimicrobial effect of cauliflower byproduct.