Heat Sensitization of Escherichia Coli by the Natural Antimicrobials Vanillin and Emulsified Citral in Blended Carrot-Orange Juice
35 Pages Posted: 29 Mar 2022 Publication Status: Published
Abstract
Efforts have been focusing on the way to overcome the impact of heating on food quality while achieving the desired shelf life. In this sense, the thermosensitization of E. coli using the natural antimicrobials vanillin (V; 0.8 and 1.0 g/L) or/and emulsified citral (C; 0.012 and 0.025 g/L) was assessed at 58 and 60°C in blended carrot-orange juice (pH 4.0; 9.0°Brix) . All combined treatments exceeded the inactivation achieved by the single thermal treatments in half the time. The inactivation of the binary treatments (V or C + heating) at 58°C was 3.84 - 0.62 log-cycles more effective than the control, particularly with vanillin. Ternary treatments (V + C + heating) at 58°C increased the microbial reduction approximately 30 %; however, at 60°C no further inactivation was observed, prevailing the thermal effect. This was verified by the higher b Weibullian parameter and the narrower frequency distributions. The selected treatments 1.0V + 0.012C at 58 and 60°C were challenged with the pathogenic E. coli O157:H7 resulting effective. In conclusion, there was an increase in heat sensitivity of E. coli due to the natural antimicrobials, particularly vanillin at 58°C. Therefore, reducing the intensity of the thermal processing will render to clean label, high-quality juices, while addressing food safety requirements.
Keywords: Vanillin, citral, heat sensitization, emulsion, mild thermal treatment, Weibull model, Escherichia coli
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