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Use of caprylic acid to control pathogens ( Escherichia coli O157:H7 and Salmonella enterica serovar Typhimurium) in apple juice at mild heat temperature
Author(s) -
Kim S.A.,
Rhee M.S.
Publication year - 2015
Publication title -
journal of applied microbiology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.889
H-Index - 156
eISSN - 1365-2672
pISSN - 1364-5072
DOI - 10.1111/jam.12926
Subject(s) - caprylic acid , salmonella enterica , escherichia coli , salmonella , food science , chemistry , bacteria , population , lactic acid , log reduction , microbiology and biotechnology , biology , biochemistry , fatty acid , medicine , genetics , gene , environmental health
Aims The aim of this study was to examine the effects of caprylic acid ( CA ) on pathogens in apple juice having intrinsic organic acids, and to determine any synergistic effects. Methods and Results Bactericidal effects of CA were examined against Escherichia coli O157:H7 and Salmonella Typhimurium present in apple juice at mild heating temperatures. Apple juice containing each of the pathogens was treated with CA (0·1, 0·2, 0·4, 0·6 or 0·8 mmol l −1 ) at 50 or 55°C. Treatment with 0·8 mmol l −1 (0·013%) CA at 50°C for 5 min or with 0·6 mmol l −1 (0·010%) CA at 55°C for 5 min resulted in the complete eradication of E. coli O157:H7 (initial population: 7·25–7·34 log CFU ml −1 ). Salmonella Typhimurium were more sensitive than E. coli O157:H7: all bacteria (7·81–7·55 log CFU ml −1 ) were eradicated by treatment with 0·2 mmol l −1 (0·0032%) CA at 55°C for 5 min or with 0·6 mmol l −1 CA at 50°C for 5 min. By contrast, when pH ‐adjusted apple juice ( pH 7·0) was treated with 0·8 mmol l −1 CA , there was no significant difference in bactericidal effects between CA ‐treated samples and controls (heat treatment alone or heat + 0·1% ethanol treatment). This result suggested that acidic pH in the apple juice boost the antibacterial effects of CA . CA treatment did not affect ( P > 0·05) the pH , colour or °Brix of the apple juice. Conclusion This study highlights the utility of CA as a natural antibacterial agent that can eliminate micro‐organisms from apple juice at very low concentrations (≤0·013%) and temperatures (≤55°C) within a short time (≤10 min). Significance and Impact of the study The results of our study may contribute to the development of an efficient method for improving the microbiological safety of apple juice.