ASSESSMENT OF MICROBIAL, MICRONUTRIENT AND MACRONUTRIENT CONTENTS OF TIGERNUT (CYPERUS ESCULENTUS) SUBJECTED TO DIFFERENT FERMENTATION METHODS.

Abstract

Tigernut (Cyperus esculentus) was subjected to different fermentation methods such as natural, backslope and control. Feeds were also formulated from the raw and fermented samples. Haematological and histopathological studies were carried out on rats fed with formulated feeds. The raw and fermented tigernut samples were analysed for microbial, mineral, proximate, amino and fatty acids contents. The microorganisms isolated and identified were: Streptococcus lactis, Lactobacillus plantarum, Staphylococcus aureus, Bacillus cereus, Bacillus subtilis, Micrococcus luteus, Aspergillus fumigatus, A.niger, A.flavus and Penicillum italicum. Results of natural fermentation showed decrease in pH value (4.4 to 3.50) and increase in total titratable acidity (0.70 to 15.80). Mineral analysis revealed potassium and sodium as the most abundant mineral elements with their values ranging from 546.00mg/100g to 677.00mg/100g and 64.00mg/100g to 3383.33mg/100g respectively while copper was found in trace amount with value ranging from 0.03mg/100g to 0.05mg/100g. Proximate composition analysis showed that naturally fermented sample had highest moisture content of 6. 05% while least value was recorded in backslope fermented whole sample (3.75%). naturally fermented whole sample had the highest protein content of 7.65% while raw sample had the highest carbohydrate value of 70.46%. Backslope fermented sample had the lowest fat content of 21.50% and highest valve in ash. The results of anti-nutrients revealed that fermentation significantly decreased oxalate (3.15 to 1.37mg/g), phytate (1.56 to 1.13mg/g) and tannin (0.14 to 0.09mg/g) contents of the nut while there was an increase in alkaloid (1.23 to 2.38mg/100g) and saponin (0.32 to 4.33mg/g). Amino acid result showed arginine as the most available amino acid present in backslope fermented whole sample (23.02g/100g) while tyrosine was the least amino acid (0.5g/100g). The oil extracted from tigernut had a greater percentage of oleic acid (73.80%). The result of the feeding trials reveals that periodic weight gain was higher (33.76gms) in rats fed with cerelac (standard) compared to weight gain (17.66gms) in rats fed with fermented sample. The results of the haematological parameters shows that rats fed with fermented samples had higher level of packed cell volume, white blood cell, lymphocytes, mean cell volume and mean cell haemoglobin concentration and platelets. Results of some biochemical markers revealed that rat fed with backslope fermented sample showed higher level of total bilirubin and alanine amino transferase. Also, the rat fed with raw and fermented feeds had various mild pathological signs on organs assessed. The overall result of the investigation revealed that backslope fermentation was the best method of fermentation that enhanced crude protein, amino and fatty acid contents of tigernut