-In this work, two-step enzymatic hydrolysis of sweet potato peel was optimized. The effects of time, enzyme dose and temperature on glucose concentration were investigated. The Box-Behnken design was applied and a total of 17 experimental runs were generated for each step. For the liquefaction step, an ANOVA test showed the quadratic model obtained to be significant (p < 0.05). The statistical model predicted the maximum glucose concentration to be 126.66 g/L at a temperature of 56.4 °C, α-amylase dose 1% (v/v) and time 60 min. A quadratic model was also obtained for the saccharification step and the model was also significant (p < 0.05). The statistical model for the second step predicted the maximum glucose concentration to be 178.39 g/L, established at the temperature of 45 °C, glucoamylase dose 1% (v/v) and time 60 min. The optimized liquefaction and saccharification conditions were validated with the actual glucose concentrations of 126.03 and 176.89 g/L, respectively.

This work was carried out in collaboration between all authors. Author JSA was the supervisor and authors ARI and TAY carried out the project work including design of the study and the draft of the manuscript. Author JF performed the statistical analysis while author ICA managed the analyses of the study and the literature searches. All authors read and approved the final manuscript.

The effects of local processing techniques on the nutrients and anti-nutrients content of bitter cassava were investigated. Raw bitter cassava tubers were boiled to produce (Rogo), sundried to produce (chips), roasted to produce (roasted chips), fried to produce (Kuese), partially fermented and sun dried to produce (Elubo), fermented by submersion to produce (Akpu) and finally, fermented by solid state to produce (yellow and white Gari). All these locally processed cassava products were subjected to proximate, mineral and anti-nutrient analysis using standard methods. The result of the proximate showed that, raw bitter cassava is composed of 1.85% ash, 64.38% moisture, 4.11% crude fibre, 1.03% crude protein, 0.66% lipids and 30.88% total carbohydrate. Mineral analysis of the raw bitter cassava tuber contained 32.00mg/100g Calcium, 12.55mg/100g Magnesium, 1.38mg/100g Iron and 80.17mg/100g Phosphorous. Even though all processing techniques significantly expose more of the the mineral content, fermentation had highest effect. The anti-nutrients analysis showed that the raw peeled tuber contained 98.16mg/100g cyanide, 44.00mg/100g oxalate 304.20mg/100g phytate and 73.00mg/100g saponin. In general all the processing techniques showed a significant reduction of the phytate, oxalate and saponin content of the cassava. However, only fermentation, sun drying and garification were able to reduce the cyanide content of bitter cassava below the safe level (10mg/100g) recommended by Standard Organization of Nigeria. Yellow gari(with the addition of palm oil) showed low cyanide content (1.10 mg/100g) than white gari (3.51 mg/100g). This also emphasis that processing methods involving fermentation reduce cyanide and other anti-nutrients in the cassava to levels that are safe for consumption and should be widely practiced.

Spices have been reported to impart nutrients, improve shelf life and overall sensory properties of foods. The incorporation of naturally occurring materials like spices in food production has proved to be a promising alternative to the use of chemicals due to public health concern. The effects of aqueous extract of Aframomum danielli at varying level of concentration on the nutritional, microbial and sensory properties of fura were investigated and analysed using standard methods. The moisture, protein, fat, crude fibre and ash content of the fura samples ranged from 51.39-54.62%, 7.49-12.02%, 1.41-1.80%, 0.41-0.99% and 0.19-0.57% respectively. The calcium, sodium, potassium, iron, manganese, magnesium and phosphorus content of the fura samples ranged from 1.9-2.4 mg/100g, 0.94-1.2 mg/100g, 0.23-0.29 mg/100g, 48.25-63.2 mg/Kg, 8.25-8.86 mg/kg, 1225-1352.7 mg/kg and 16.72-18.44 mg/kg respectively. The bacteria and mould count ranged from 15-30 x 105 cfu/g and 10-20 x 105 cfu/g respectively. The bacteria count of the untreated fura increased 10-fold while the mould count tripled after 48 hours of production. There existed significant differences (P>0.05) between the untreated and treated fura samples in all the parameters examined. The treated fura samples compared favourably with untreated sample in all the sensory properties evaluated, while being more acceptable after 48 hours of production. The use of the aqueous extract of Aframomum danielli brought about a general increase in the nutritional properties of fura samples, reduced microbial load, thus improve shelf stability and general acceptability of fura analysed.