EFFECTS OF DIFFERENT DRYING AND STORAGE METHODS ON THE AFLATOXIN CONCENTRATION OF GROUNDNUTS (Arachis hypogaea Linn) IN THE NORTHERN REGION OF GHANA

Abstract

Arachis hypogaea Linn is a very important cash crop and of great nutritional value but has a high tendency to be infested with aflatoxin by Aspergillus flavus. A survey was conducted to find out the general levels of aflatoxin contamination in dried groundnuts in storage over a period of three months in Northern Region. Groundnuts samples were taken from a total of five hundred households in twenty communities using purposive sampling. Aflatoxin analysis on the samples was carried out using Flouro Quant AflaPlus machine. Aflatoxin concentrations obtained were in the range of 11.08ppb to 367.5ppb for the samples in storage over a period of three month whilst those that were tested freshly from the field were in the ranges of 4.35ppb to 13.06ppb with one abnormality recorded at 110ppb in a community called Tarikpaar. Different drying treatments were used on the fresh samples after which they were tested for aflatoxin after being in storage over a period of three (3) months in different storage bags. The results obtained showed that the best method for the reduction of aflatoxin levels in peanuts was to dry them on tarpaulin and store them in platic bags and placed on pallets. This treatment gave the lowest reading of 21.03±27.91 ppb in the aflatoxin concentration. Isolations of fungi species were done using dilution and direct plating method from groundnut samples with aflatoxin concentrations above 30ppb and those below 10ppb to identify the fungi species responsible for the high and low aflatoxin values recorded. The percentage occurrence of these species were found to be 60% for Asperghillus flavus , 20% Aspergillus niger, 15% Aspergillus parasiticus and the last two species Rhizopus stolonifer and Penicillium chrysogenum had 5% occurrence respectively. The findings from this works recommend that tarpaulin should be used by farmers for drying their nuts and storage should be done in a plastic bag stored on a raised structure. It also recommends that plugging of nuts should be done right immediately after harvest