Effect of Addition of Yellow-Fleshed Sweet Potato Flour (Ipomoea batatas) and Fermentation on Chemical, Functional, Microbial and Sensory Attributes of an Instant Fura Powder

Aim: The objective of this work was to produce instant fura powder from the addition of yellow-fleshed sweet potato flour with millet flour and fermentation.

Methodology: Pearl millet flour and yellow fleshed sweet potato flour was used to produce fura in the ratio 90:10, 80:20, 70:30, 60:40 and 50:50 with traditional fura (TF) 100% pearl millet as the control sample. However, preliminary sensory evaluation was conducted on the various blends and 70:30 ratios were most preferred which was used to prepare the final blend ratio of fermented and Non-fermented blended fura (FBF and NFBF) respectively. The samples were subjected to standard analytical methods for their chemical, functional, microbial and sensory attributes of the product.

Results: The protein contents ranged from 12.95 to 18.60%. The FBF and NFBF were not significantly different (P≤0.05) but shows variation to the TF. The TF had the highest content of 77.12% and 364.78kj/kg, followed by 69.12% and 355.45 kj/kg while the FBF had 68.03% and 345.56kj/kg of carbohydrate and energy value respectively. There were no significant different (P≤0.05) in the ash, crude fibre, and fat content of the samples analyzed. The moisture content of the samples ranged from 5.00 to 9.20%. The selected functional properties of the samples during three months storage showed that there was significantly different (P≤0.05) between the loose and packed bulk density throughout the storage periods but there was no different in the TF and FBF samples in their packed bulk density. However, FBF had the lowest bulk density throughout the storage period. The reconstitution index (RI) and water absorption capacity (WAC) showed there were no significant different (P≤0.05) between the TF and NFBF throughout the storage periods. The NFBF had the highest value of bulk density (packed) and reconstitution index of 0.81 and 42.67g/cm3 respectively while the TF had the highest value of WAC of 36.87g/cm3 during the third month storage. The calcium content ranged from 276.00 to 329.67mg/100. The iron content ranged from 60.00 TF to 80.13mg/100g for FBF. However, FBF had the highest value of 3.92 and (1.31 mg/100 g) of pH and titratable acidity (TTA) respectively. The 0Brix level ranged from 3.0 to 5.02. There were no significant (P≤0.05) in the beta-carotene content, the value ranged from 0.26 to0.44mg/100g. The phytate content ranged from 0.34 to 0.73mg/100g. The microbial results revealed that total viable count (TVC) of all the samples were within the acceptable limit during the three months storage. While the total mould and yeast count (TMYC) results revealed that the TF and NFBF sample had too numerous to count (TNTC) of TMY on the last week of the storage duration while the FBF sample is still within the microbial limit of detection (LOD). Total coliform count (TCC) showed that no coliform count was detected. There were no significant different (P≤0.05) in the texture of FBI and NFBF and the taste of TF and FBF. There was no significant different (P≤0.05) in the colour and overall acceptability of the all the samples.

Conclusion: It was evident from the study that fermentation had improved the proximate, functional compositions significant (P≤0.05), also reduced the phytate content and extend the shelf life of the products. More so, addition of yellow-fleshed sweet potato had greatly increased the mineral, vitamins, sugar contents and overall acceptability of the products. Apparently, this work has shown that more value would be added to sweet potato utilization.