MYCOFLORA AND AFLATOXIN LEVELS IN WALNUT SAMPLES STORED IN DIFFERENT PACKAGING MATERIALS IN OGUN STATE

Abstract

Aflatoxin levels in nuts and fruits pose a great threat to food storage and availability. This study aimed at determining the mycoflora and aflatoxin level in stored walnut under various conditions. Freshly harvested walnuts were stored for 90 days in three different media: jute bags, Plastic containers and sterile polythene bags under room (37ᵒC) and refrigeration (4ᵒC) temperature. After 90 days of storage, the stored walnuts were examined for fungal growth at one month interval after which colonial and morphological characterization were carried out to identify the fungi present. Proximate analysis and aflatoxin content of the walnut samples were determined by standard methods. Fungi isolated from the walnuts include; Aspergillus niger, Saccharomyces cerevisae, Penicillum notatum, Aspergillus sydowi, Fusarium oxysporium, and Rhizopus stolonifer. Walnuts stored in plastic container at room temperature had the lowest aflatoxin level of 0.002 ng/kg while that stored in polythene bags had the highest (0.054 ng/kg). Proximate analysis also revealed that walnuts stored in polythene bag reduced significantly (p<0.05) in protein, ash content, fat, fibre, moisture and carbohydrates while samples stored in jute bag and plastic container remained unchanged. This study shows that storage methods contributed to the overall quality, shelf life and aflatoxin content of walnut and hence care should be taken during post harvesting process.