Thesis Abstract

The nutrient composition of yeast biofortified akamu, a cereal-based fermented food was determined using two different concentrations of inocula preparations at 5% and 10% glucose concentrations. While keeping the peptone and yeast extract constant at 2% and 1% respectively. These media were used to inoculate the akamu at different volumes of 2.5 ml, 5 ml and 7.5 ml and later incubated at room temperature (25oC) for 72 hours after which they were analysed. The yeast used in this research was Pichia kudriavzevii. The result of the analysis showed that the pH of yeast biofortified akamu (YBA) reduced as the volume of the inocula increased for both concentrations of glucose while the titrable acidity increased in YBA as the volume of the inocula increased for both concentrations of glucose. The protein and reducing sugar contents of YBA increased significantly (p < 0.05) as the volume of the inocula increased for the two glucose concentrations. The carbohydrate and fibre contents of YBA was not significantly (p > 0.05) reduced while the fat and ash contents of YBA was not significantly altered. The increase and decrease in amino acids content of YBA at 5% and 10% glucose concentrations were not volume dependent. Relative to the unfortified akamu, the YBA at 10% glucose concentration yielded higher amounts of amino acids than YBA at 5% glucose concentration. Alanine, cysteine, phenylalanine, tyrosine and tryptophan contents increased as the volume of inocula increased for both media inoculated in YBA. In the case of proline, there was an inverse relation with inoculum volume. The vitamin contents of yeast biofortified akamu at 5% and 10% glucose concentrations showed no significant change in the amount in the YBA compared to the ordinary akamu except the amount of vitamin A that was significantly reduced (P < 0.05) at both glucose concentrations. In the mineral contents of YBA inoculated at 5% and 10% glucose concentrations, the calcium, copper, manganese and zinc contents increased at both concentrations though, the increase was not volume dependent. Magnesium and iron conrtents increased at both concentrations except in YBA inoculated with 2.5 ml at 5% glucose and sodium and potassium in YBA inoculated with 2.5 ml and 5 ml at 5% glucose concentration. There was a significant reduction (P < 0.05) in phosphorous content of YBA at all the three volumes at 5% glucose and also for 2.5 ml and 5 ml inocula at 10% glucose concentration. It is concluded from this study that yeast (Pichia kudriavzevii) can serve as a vehicle for biofortification and that YBA inoculated at 10% glucose concentration yielded more nutrients compared to that inoculated at 5% glucose concentration.

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