Effect of gamma irradiated Lactobacillus bacteria as an edible coating on enhancing the storage of tomato under cold storage conditions

Abstract

ABSTRACT This study was carried out during the two successive seasons of 2017 and 2018 to study the effect of both unirradiated and irradiated Lactobacillus paracasei cell-free supernatant in combination with glycerol and starch as well as gelatin as an edible coating (G/S/G unirradiated LAB supernatant and G/S/G irradiated LAB supernatant edible coating) on preserving tomato fruits under cold storage conditions. Thirteen lactic acid bacteria (LAB) were isolated from 20 samples of dairy products from local markets. The best LAB isolate gave the highest antimicrobial activity against 27 pathogenic bacterial strains isolated from injured tomato fruits and it was identified by 16SrRNA phylogenetic identification as Lactobacillus paracasei. Antagonistic activity of this isolate exposed to different doses of gamma radiation against the isolated pathogenic bacteria was examined. It was found that 3.5 KGy irradiation dose increased the antimicrobial activity of LAB isolate. On the other hand, it was found that both edible coatings gave better results than untreated fruits such as diminishing weight loss, decay percentage, higher ascorbic acid, lycopene, titratable acidity, total sugars and total soluble phenols concentration as well as lower bacterial load, T.S.S./T.A. than uncoated fruits.