Postharvest Technology Program, School of Bioresources and Technology, King Mongkut's University of Technology Thonburi, Bangkok, 10140, Thailand

Abstract

Storage of ‘Khon Kaen 84-8’ peanut kernels in laminated bags (Low density polyethylene (LDPE)/Nylon) (20_30 cm; 120 mm thickness) under different packaging atmospheres had effect on quality, fungal occurrence and aflatoxin B1 (AFB1) contamination. During fifteen week storage, peanuts (6.4% moisture content) were kept under different packaging atmospheres with some inoculated (Inoc.) and without (Non-Inoc.) aflatoxin producing fungus Aspergillus flavus. The treatments include; 100% CO2þInoc., 100% N2þInoc., vacuum þ Inoc., Air þ Inoc., and Air þ Non-Inoc. packed with only ambient air. The storage room conditions were a temperature of 29±2 _C and 70 ± 5% r. h. Mycobiota occurrence, AFB1 level, moisture content, lipase activity, free fatty acids and rancidity (Thiobarbituric acid; TBA value) were investigated. A total of five major fungi were identified with four storage fungi and one field fungus; Rhizopus stolonifer, Aspergillus niger, A. flavus, Penicillium spp., and Fusarium spp., respectively. Packaging in 100% CO2þInoc. Significantly repressed the fungal occurrence especially A. niger while all other packaging atmospheres suppressed proliferation of both R. stolonifer and Penicillium spp. The peanuts kept in vacuum þ Inoc. Package revealed AFB1 level below detection limit (0.4 mg/kg). Peanut kernels in 100% CO2þInoc. Packaging atmosphere maintained an acceptable color indicated by L* and a* values, as well as the color change (DE) compared to other treatments. Different packaging atmospheres showed variable results in relation to the free fatty acids level with packaging under 100% N2 revealing the lowest. Subsequently, 100% N2 packaging atmosphere relatively inhibited rancidity occurrence in peanut kernels during storage. The results of this study portray that 100% CO2, 100% N2 and vacuum packaging atmosphere could have a potential to suppress occurrence of mycobiota, maintain peanut kernel quality in relation to color and lipid oxidation, and as well curtail AFB1 contamination respectively, for fifteen weeks or more given the quality of kernels at the end of storage.