Antibacterial Activity of Irradiated Powdered Tetrapleura tetraptera Fruit and the Moisture Sorption Isotherm of the Whole Fruit

Abstract

Aim: To assess the microbial load and antibacterial activity of irradiated T. tetraptera fruit and the appropriate equilibrium relative humidity for the storage of irradiated fruit of T. tetraptera. Methodology: The whole fruit was analyzed for aerobic mesophiles count and moisture sorption isotherm was determined; while the powdered samples were analyzed for antibacterial potency. Results: Irradiating the samples reduced the microbial load significantly. A dose of 10 kGy eliminated all microflora from the products while a dose of 5 kGy reduced the initial microbial count from 1.1x104 to 80 CFU/g (i.e. 93% reduction). The net gain of moisture by fruits stored at 55% to 75% ERH was minimal and no growth of fungi was observed on the fruits. ERH above 75% reintroduce some microbes. Conclusion: Irradiation completely eliminated the microflora at 10 kGy and substantially reduced the antibacterial ability of T. tetraptera fruit against the bacteria strains studied. The irradiated and unirradiated T. tetraptera fruits were better stored up to 75% equilibrium relative humidity.