sodium-hypochlorite and chlorous-acid

The objective of this study was to investigate the effect of nisin in combination with heat or antimicrobial chemical treatments (such as lactic acid, chlorous acid, and sodium hypochlorite) on the inhibition of Listeria monocytogenes and total mesophiles in sturgeon (Acipenser transmontanus) caviar. The effects of nisin (250, 500, 750, and 1,000 IU/ml), lactic acid (1, 2, and 3%), chlorous acid (134 and 268 ppm), sodium hypochlorite (150 and 300 ppm), and heat at 60 degrees C for 3 min were evaluated for a five-strain mixture of L. monocytogenes and total mesophiles in sturgeon caviar containing 3.5% salt. Selected combinations of these antimicrobial treatments were also tested. Injured and viable L. monocytogenes cells were recovered using an overlay method. Treating caviar with > or =500 IU/ml nisin initially reduced L. monocytogenes by 2 to 2.5 log units. Chlorous acid (268 ppm) reduced L. monocytogenes from 7.7 log units to undetectable (<0.48 log units) after 4 days of storage at 4 degrees C. However, there were no synergistic effects observed for combinations of nisin (500 or 750 IU/ml) plus either lactic acid or chlorous acid. Lactic acid caused a slight reduction (approximately 1 log unit) in the microbial load during a 6-day period at 4 degrees C. Sodium hypochlorite was ineffective at the levels tested. Mild heating (60 degrees C for 3 min) with nisin synergistically reduced viable counts of L. monocytogenes and total mesophiles. No L. monocytogenes cells (<0.48 log units) were recovered from caviar treated with heat and nisin (750 IU/ml) after a storage period of 28 days at 4 degrees C.

Topics: Animals; Anti-Bacterial Agents; Chlorides; Colony Count, Microbial; Dose-Response Relationship, Drug; Fish Products; Food Handling; Food Microbiology; Food Preservation; Lactic Acid; Listeria monocytogenes; Nisin; Sodium Hypochlorite; Temperature; Time Factors

This study was undertaken to compare the efficacies of chlorous acid (268 ppm), sodium hypochlorite (200 ppm), and lactic acid (2%) in eliminating total mesophilic microorganisms, Salmonella Typhimurium, and Listeria monocytogenes on commercial mung bean sprouts immediately after treatment and during posttreatment refrigerated storage. Treatment with sodium hypochlorite for 10 min did not reduce the total aerobic count. However, treatment with lactic acid and chlorous acid for 10 min initially reduced the total aerobic count by 0.6 and 0.8 log CFU/g, respectively, and maintained the same level or a lower level of the total aerobic count during the storage time. Treatment with chlorous acid reduced Salmonella Typhimurium from 5.0 log to undetectable levels (<0.48 log CFU/g), and the pathogen remained undetectable over a 9-day storage period. Treatment with lactic acid resulted in an initial 3-log reduction and further reduced the number of Salmonella Typhimurium cells to undetectable levels after 3 days. For L. monocytogenes, treatment with chlorous acid resulted in an initial 5-log reduction, and treatment with lactic acid resulted in a 2-log reduction at the beginning and undetectable levels after 9 days. When chemically injured cells were investigated by the selective overlay method, no statistical difference was observed (P < 0.05) between the number of injured cells recovered following treatment with chlorous acid and the number of bacteria counted on selective media, whereas sodium hypochlorite generated more injured cells than the other treatments did. These data suggest that treatment with chlorous acid may be useful in reducing total mesophilic microorganisms, Salmonella Typhimurium, and L. monocytogenes in commercial mung bean sprouts.

Topics: Chlorides; Colony Count, Microbial; Disinfectants; Fabaceae; Food Handling; Food Microbiology; Lactic Acid; Listeria monocytogenes; Salmonella typhimurium; Sodium Hypochlorite; Time Factors; Treatment Outcome