Cassia oil for controlling plant and human pathogens on fresh strawberries

Abstract

The inhibitory effects of cassia oil on the human pathogen Escherichia coli serotype O157:H7 and the plant pathogen Botrytis cinerea were tested in vitro at different concentrations (200–800 ppm). Cassia oil exhibited antibacterial and antifungal activity against both pathogens. Cassia oil at 400–800 ppm inhibited the growth of E. coli O157:H7 in vitro and on the surface of treated strawberries. Cassia oil also completely inhibited the growth of B. cinerea at 400–800 ppm. Spore germination and germ tube elongation of the pathogens in potato dextrose broth were strongly inhibited in the presence of 100 ppm cassia oil. Cassia oil at all concentrations reduced the percentage of decayed strawberries. Experiments on reducing the development of natural decay in strawberries gave similar results. None of the quality parameters tested (colour, total soluble solids, pH, total acidity and ascorbic acid) was affected by cassia oil treatment. Storage experiments on strawberry showed that the percentage weight loss was reduced by cassia oil treatment. Hence, cassia oil could be an alternative to synthetic chemicals for controlling human and plant pathogens on fruits such as strawberries during postharvest and storage.