Antimicrobial efficacy of vanillin in conjunction with mild heat treatment against Escherichia coli O157:H7 in sweetened lassi

Abstract

Dairy foods are prone to contamination by pathogens and spoilage microorganisms at various stages of production and distribution. Escherichia coli O157: H7 is potent shiga toxin producer that leads to human illness. Synthetic antimicrobial are used in processed dairy products to improve food safety and enhance self life. The print and electronic media have created awareness about adverse health effect of synthetic chemical used as preservatives in foods and “green consumerism” among health consumers. Now a day’s consumer prefers foods without or limited concentrations of chemicals as a part of “green consumerism”. This has driven the attention of food manufacturer’s for use of natural antimicrobials to enhance food safety and self life. The present investigation was aimed to evaluate antimicrobial efficacy of vanillin in conjunction with mild heat treatment against E. coli O157: H7 in sweetened Lassi , a very popular Indian fermented milk dairy drink to improve its food safety against E. coli O157: H7 and shelf life in conjunction with mild heat treatment. Escherichia coli O157:H7 was exposed to different mild heat treatments (52, 55 and 58 °C) and vanillin concentrations @900, 1400 and 1900 ppm. The results were validated by Weibull parameters of survival curves fitting in Mafrat model equation. The observations on antimicrobial efficacy of vanillin in conjunction with mild heat treatment revealed that low temperatures exhibited protective effects to the target organism i.e. E. coli O157:H7. The vanillin addition enhanced the inactivation rates of E. coli O157:H7 at any mild heat treatment given. Significant differences (P<0.05) were recorded in Weibull parameters of survival curves and time taken for 4 log cell reduction in populations. These results demonstrated that combined process of vanillin and mild heat treatment could be a potential approach to control E. coli O157:H7 in sweetened Lassi an Indian fermented dairy drink vis a vis other fermented and non fermented dairy products. These finding would enable the dairy or food industry to manufacture milk and milk products with improved food safety and shelf life.