Effect of Pre-treatment Methods on the Quality Characteristics of Stored Irvingia kernel

Abstract

Aims: To evaluate effects of pre-treatment methods on the keeping quality of stored Irvingia kernels using ethanol and Ash from palm fronds as preservative agents. Study Design: Study of the microbial isolation using sabouraud dextrose agar and nutrient agar, introduction of these microbial isolates on the differently treated freshly harvested Invingia kernels under experimental conditions. Place and Study Duration: Department of Applied Microbiology and Brewing Nnamdi Azikiwe University, PMB 5025, Awka, Anambra state, Nigeria between March, 2013 to September, 2014. Methodology: Sample collection, kernel extraction, treatment with Ash and ethanol and storage in a storage shelf for a period of six (6) months then microbial enumerations and chemical analyses. Effectiveness of each preservative agent were assayed both chemically and microbiologically. Results: Results showed that the pre-treated samples had better quality characteristics than that of the control sample at the end of the storage period. Fungal population of the pre-treated samples differed significantly with the untreated sample (control) at (P<0.05). Total aflatoxin analysis carried out on the samples was positive for the control sample only thus, depicted a contamination by Aspergillus flavus which was identified in the control sample. Aflatoxin concentration of 13.90 ppb was reported. This is above the National Agency for Food and Drugs administration and Control, Nigeria (NAFDAC) recommended maximum permissible level in food (10 ppb). Zero bacterial counts upon enumeration using  nutrient agar  was reported in both treated and untreated samples and therefore, suggested that preponderance of the Irvingia kernels post- harvest spoilage organisms are fungi. Conclusion: Results from this work showed that pre-treatment of Irvingia kernel with ethanol before storage significantly improved the chemical and microbial quality characteristics of the Irvingia kernel during the storage. Pre – treatment with the ethanol also reduced the fungal populations of the stored Irvingia kernels and inhibited the growth of Aspergillus flavus which is a known aflatoxin producer. It is therefore recommended that Irvingia kernel be pre – treated with ethanol before storage as this will not only improve the storage quality of the Irvingia kernel but will also guarantee health and safety of the people that consume the kernel.