Postharvest dip treatment of Bacillus subtilis for maintaining quality and shelf life of guava cv. Allahabad Safeda

Abstract

In North India, guava fruits are harvested twice in a year yet maintaining the quality during storage is still a challenge due to its perishable nature. The use of chemicals for extending shelf life of guava should be avoided due to food safety concern since it is consumed along with skin. Recently bio-agents are being used as dip treatment for effective control of storage pathogens like Colletotrichum sp., Pestalotiopsis sp.and Lasiodiplodia sp. in fruits like apple, pear and strawberry. However, no such report is available for guava. In the present study Bacillus subtilis was used as bio-agent for enhancing the shelf life of guava. Guava fruits cv ‘Allhabad Safeda’ were subjected to post harvest dip treatments for 30 minutes with four strains of Bacillus subtilis viz. MTCC 7607, 7606, 7612, and 7605 @ 108cells/ml dip solution and stored at 18 ±2oC and 57±5 % R.H. The fruits were analyzed for physico-chemical parameters as well as microbial population at regular intervals. Among the treatments, fruits treated with Bacillus subtilis strain MTCC 7607 showed highest firmness after 10 days of storage. In general bio-agent treated fruits were glossy in appearance, better in quality and taste with uniform colour development and least disease incidence.Surface microbial analysis reflected the dominance of treated bacterial strain over other micro-organisms. Preliminary results indicate that Bacillus subtilis strain MTCC 7607 @ 108cells/ml could act as a potent bio-agent for shelf-life extension of guava to control postharvest diseases.