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Effects of organic acid alone and in combination with H2O2 and NaCl on Escherichia coli O157:H7: An evaluation of antioxidant retention and overall acceptability in Basil leaves (Ocimum basilicum)

Valiolahi, Masome, Najafi, Mohamad Ali, Eskandani, Majid Alipour, Rahnama, Mohamad
International journal of food microbiology 2019 v.292 pp. 56-63
2,2-diphenyl-1-picrylhydrazyl, Escherichia coli O157, Ocimum basilicum, acetic acid, antioxidant activity, ascorbic acid, basil, citric acid, cold storage, gallic acid, hydrogen peroxide, lactic acid, leaves, sanitizers, sanitizing, sensory properties, sodium chloride, temperature
In this study, the efficacy of household sanitizers application on reduction of Escherichia coli O157:H7, ascorbic acid, total phenolics, DPPH (2,2-diphenyl-1-picrylhydrazyl) radical scavenging and overall acceptability of inoculated fresh basil leaves (Ocimum basilicum), at temperature of 40 °C was investigated. Sanitizers containing lactic acid (LA), acetic acid (AA) and citric acid (CA) were used at concentration of 2%, individually or in combination with H2O2 (1% or 2%), and NaCl (7%). Control a and b were unwashed and washed leaves with distilled, deionized and sterilized water, respectively. All sanitizing treatments, in comparison to the control a, reduced the numbers of E. coli O157:H7 (0.24 ± 0.12–3.37 ± 0.48 log CFU/g) at day 1 (1 h after sanitizing). The lowest number of E. coli O157:H7 population (2.35 ± 0.26 log CFU/g) was observed by applying the LA + H2O2 (%2) treatment at first day of chilled storage. The highest amount of ascorbic acid (27.77 ± 0.06 mg/100 g), total phenolic (112.2 ± 0.5 mg gallic acid equivalents/100 g) and DPPH radical scavenging activity (95.2 ± 0.5%) was observed in control a at first day (P < 0.05). The results showed that the amount of ascorbic acid, total phenolics, DPPH radical scavenging activity and overall acceptability of basil leaves decreased during chilled storage. On day 2 of storage, the scores of sensory attributes for the control group were less than the minimum score of acceptance (i.e. 5 points). The results of this study indicated that LA + H2O2 (2%) treatment rendered the samples favorable in terms of overall appearance (≥5) up to 48 h.