Poster Topical Area: Nutritional Microbiology
Poster Board Number: 244
OBJECTIVES: This study was carried out to determine the levels of Cyanide, Phytate and Tannins; which are anti-nutrients in gari produced from fermented yellow fleshed cassava using eight varieties.
METHODS: Eight varieties of yellow fleshed cassava were collected from the Ubiaja sub-station of the International Institute of Tropical Agriculture (IITA) Ibadan. They were peeled, washed, grated and stored in sacks for fermentation over a period of 4 days. Samples of the fermenting cassava were collected every day from each variety, and roasted over open fire, as done locally, to obtain a granulated product called gari. The gari samples were then subjected to analyses.
Phytate determination: Known weight of each sample was placed in differently labelled flasks and 100mL of 2% HCl was added and allowed to stand for 3hrs. Then filter and add distilled water to give proper acidity. The phytic acid in samples was then titrated against Iron chloride solution using 0.3% ammonium thiocyanate solution as indicator.
Tannins determination: Spectrophotometric method, read at 250nm was used to estimate the level of Tannins.
Cyanide determination: Known weight of each variety was placed in a flask containing 2mL of Orthophosphoric acid to liberate hydrocyanic acid (HCN). The HCN liberated, is then titrated against 0.01M silver nitrate solution using 1.6mL of 5% potassium iodide solution as indicator.
RESULTS: Phytate: the results show a significant decrease (p<0.05) in level in all the eight varieties studied, for example IBA011368 recorded 8.24±0.01mg/g for Day 0 of fermentation and recorded 3.31±0.01mg/g for Day 4 of fermentation. While IBA141092 recorded the highest amount of phytate in Day 0 (19.77±0.01mg/g), IBA061635 recorded the highest at Day 4 of fermentation (11.54±0.01mg/g). Tannins: The levels in most of the varieties did not show any significant change (p>0.05) from Day 0 to Day 4 of fermentation. However, a few recorded a significant reduction (p<0.05) as the period of fermentation increases. Overall, variety IBA141092 recorded the highest level at Day 0 (0.20±0.00) and 0.18±0.00 for Day 1 which was also the highest for all the varieties for this period.
Cyanide: the study shows that the level of cyanide significantly decreased (p<0.05) from Day 0 to Day 4 in all the varieties studied. In the case of IBA011368 it was 10.39±0.00 mg/Kg for Day 0 and 4.15±0.01mg/Kg for Day 4.
CONCLUSION: This study has shown that yellow cassava has to be fermented for not less than 4 days to reduce the level of the residual toxic cyanide in gari and to also reduce the level of phytate. This study also shows that the level of tannins is not affected by fermentation of the yellow cassava before roasting into gari
Ambrose Alli University, Ekpoma.
Ekpoma, Edo, Nigeria