Antibacterial properties of combined non-thermal treatments based on bioactive edible coating, ozonation, and gamma irradiation on ready-to-eat frozen green peppers: evaluation of their freshness and sensory qualities
Résumé
Antibacterial activity of an optimized formulation (edible coating), gaseous ozone, γ-irradiation treatments, and their combinations on ready-to-eat frozen pre-cut green peppers against Escherichia coli, Salmonella enteric, and Listeria innocua as foodborne pathogen bacteria, was assessed. In situ results showed that the antibacterial coating presented a large spectrum activity against Gram-positive and Gram-negative bacteria. In addition, ozone gaseous treatment at concentration of 10 ppm during 5 min allowed a total inhibition of E. coli after 4 days and a noticeable log reduction in Listeria and Salmonella during storage time. According to the obtained results, irradiation was the most effective technique to inhibit the growth of bacteria in alone or combined treatments. Different treatments had no significant impact on color parameters of pre-cut green peppers. Furthermore, no significant effect on chlorophyll content of pre-cut green peppers was also observed which is in accordance with the colorimetric results. Some statistical differences were noted in vitamin C content of pre-cut green peppers after coating treatment due to the additional ascorbic acid content in coating formulation, although no negative effect of treatments on the quality of pre-cut green peppers (total AA + DHA content) was observed. Furthermore, the sensory analysis confirmed that treatments had no significant effect (p > 0.05) on sensory attributes of peppers (color, odor, and taste).