MICROBIOLOGICAL QUALITY, NUTRITIONAL CONTENT AND AFLATOXIN-PRODUCTION POTENTIAL OF ISOLATED ASPERGILLUS SPECIES OF “KATI”; A FERMENTED SORGHUM BASED FOOD

Abstract

This study was designed to evaluate the microbiological quality, nutritional content and aflatoxin potential of Aspergillus flavus associated with kati. The sorghum seeds were purchased from Oba Market, Akure while the kati was obtained from four different locations namely Akungba, Ikare, Oka and Okeagbe in Akoko area of Ondo State, Nigeria. The sorghum seeds were cleaned, sorted, soaked, wet-milled and then fermented for 72 hours prior to kati production. Isolation of microorganisms was carried out using 10-fold serial dilution and pour plate techniques. The pH and total titratable acidity of the fermented sample were monitored on daily basis during the fermentation process. The aflatoxigenic test on the isolated A. flavus was carried out. The proximate, antinutrient, mineral and vitamin contents of the samples were determined using various chemical methods. The aflatoxin content of the samples were also determined. The highest bacterial counts of 4.7x105 cfu/g was obtained from sorghum with least counts 3.0x105 cfu/g from kati purchased from Okeagbe Akoko. Sorghum recorded highest fungal counts 4.7x105 sfu/g followed by kati purchased from Akungba Akoko with 4.5x105 sfu/g while the least fungal counts was found from kati purchased from Oka Akoko and Ikare Akoko respectively with 3.0x105 sfu/g. The pH of the fermented samples from Okeagbe, Oka, Ikare, Akungba and laboratory made kati decreased from 5.20 to 4.21, 5.90 to 5.01, 5.72 to 4.27 and 5.94 to 3.81 with increase total titratable acidity from 1.04 to 1.98, 1.09 to 2.24, 0.88 to 2.65, 1.02 to 2.64 and .97 to 2.43 respectively. . The amino acids analysis revealed that all the samples had good essential amino acids with glutamate being the highest, while valine and cyestein had the lowest values in all the samples. The distribution of aflatoxigenic strain recorded high value 3(27.3%) in Ikare sample with the least 1(9.09%) from Oka sample when compared with the laboratory made kati with no aflatoxigenic strain. The carbohydrate content increased in all the samples. High protein content of kati 13.43% was obtained from Akungba sample when compared with other samples. There was no significant difference (p<0.05) in the crude fibre and ash contents of kati. High fat content 9.87% was obtained from Okeagbe sample while low moisture content was obtained from sorghum when compared with other samples. High phytate and glycoside contents were recorded from all the samples. Laboratory made sample had increase in oxalate and phenol contents 14.03mg/g and 13.87mg/g respectively. Tannin content 15.00mg/g was obtained from Oka sample. All the samples had high phosphorus content. Samples from Okeagbe, Ikare, Akungba and sorghum recorded high aflatoxin A content while Oka sample recorded high aflatoxin B1 with no significant difference (p<0.05) in aflatoxin content obtained from laboratory made kati. The reduction in aflatoxin content of the laboratory made kati from sorghum with improved nutritional content suggest its importance as cheap and readily available raw material in the production of foods, safe for human consumption.