S.O. Awonorin

Effect of Texture Modifiers on the Physicochemical and Sensory Properties of Dried Fufu

Glycerol monostearate (GMS) and monoglyceride phosphate (MGP) were added to fufu flour at different levels (0.5%, 1.0% and 1.5%) in hydrated and powdered form. There were evaluated the effects of those additives on physicochemical and sensory properties of dried fufu. Addition of GMS and MGP had a significant effect on the swelling power, solubility, pasting properties and sensory quality of fufu flour. Results obtained were: Dispersibility (69%-70.33%), water absorption index (WAI, 47.7%-54.4%), least gelation concentration (LGC, 4.67%-6.67%) and water absorption capacity (WAC, 119.3%-136%) for the fufu flour treated with GMS and MGP. Solubility of the samples mixed with the powdered form of the modifier ranged between 23.2% and 31.7%, while that of the samples mixed with the hydrated form of GMS and MGP ranged between 5.3% and 12.7%. The pasting time varied between 8.25min and 18.50min, fufu flour mixed with 1.5% GMS powder had the lowest value while that mixed with 1.0% MGP powder and 0.5% hydrated MGP recording the highest value. Pasting temperature ranged from 67.00°C to 72.00°C, with flour mixed with 1.0% hydrated GMS and 0.5% GMS powder having the lowest and highest value, respectively. The highest value of peak viscosity (762.50BU) was recorded by fufu flour containing 1.0% hydrated GMS. The lowest value of starch stability (255.50BU) was recorded by fufu flour without modifier while the highest value (499.00BU) was recorded by fufu flour containing 0.5% GMS powder. There were significant differences (p 0.05) in the sensory qualities except for colour of fufu flour samples. The overall quality index (OQI) comprised between 5.24 and 6.01, fufu sample containing 0.5% hydrated GMS had the lowest OQI and that containing 1.0% hydrated MGP the highest OQI. Addition of 0.5% texture modifier to dried fufu may be economically feasible according to the estimated cost of production.

Optimization of Blanching Conditions Prior to Deep Fat Frying of Yam Slices

The effect of low-temperature blanching and frying time at a frying temperature of 170°C on moisture and oil contents, breaking force and colour of yam chips was investigated using response surface methodology to establish the optimum blanching conditions and frying time. A central composite rotatable design was used to study the effects of variation in levels of blanching temperature (60–80°C), blanching time (1–5 min) and frying time (2–6 min) on quality attributes of yam chips. The effect of blanching temperature and frying time was more significant than the time of blanching on the quality attributes. The response variables were fitted to predictive models applying multiple linear regressions. Statistical analysis with response surface regression showed that moisture content, oil content, breaking force and L* (lightness) parameter were significantly (P < 0.05) correlated with blanching temperature and time and frying time. However, the regression equation showed a poor fit for a* and b* respectively. The optimum conditions were a blanching temperature of 70–75°C, blanching time of 4–5 min while frying for about 5 min.

Evaluating Some Empirical Models for Predicting Water Absorption in African Breadfruit (Treculia Africana) Seeds

Abstract Water absorption process during soaking of African breadfruit (ABF) seeds was studied at five typical soaking temperatures, ranging between 30 and 70°C. The progress of water absorption by the seeds followed an exponential increase with increase in temperature. The experimental data were fitted to three empirical equations. All the equations were able to explain over 90% of the experimental data. The predicted water absorption capacity (M e ), which ranged between 68 and 92/100 g dry solid were not significantly affected by temperature changes (p > 0.05) while the time to achieve maximum water absorption capacity ranged between 9 and 140 h. The water absorption rate constant in Singh–Kulshresthas model was more sensitive to temperature changes than from the others. By applying Arrhenius equation, it was shown that water absorption at 30–70°C was the predominant process responsible for the changes in mass of ABF seeds. The differences in the experimental and predicted data from the three models were compared to evaluate their goodness of fit. The chi-square and the root mean square deviation (RMSD) showed that Singh–Kulshrestha and Pilosofs models described better the moisture variation in soaked ABF seeds with time. In terms of residual moisture plots, Singh–Kulshresthas model gave a more random distribution at all soaking temperatures, making it a better fitting equation.

Evaluation and Optimization of Steam and Lye Peeling Processes of Sweet Potato (Ipomea batatas) using Response Surface Methodology (RSM)

Abstract Sweet potato of uniform sizes and shape were subjected to steam peeling (temperature 80–100°C and peeling time 5–15 min) and lye peeling (sodium hydroxide concentration 8–12%, temperature 80–100°C and peeling time 3–5 min). Response surface methodology was used to analyze and optimize the process parameters in each case. For steam peeling, the peel loss and unpeeled surface area were 6.85 and 28.16%, respectively, while optimum peeling conditions where temperature and peeling time of 100°C and 5 min, respectively, for minimum peel loss and unpeeled surface area. For lye peeling, however, the peel loss and unpeeled surface area were 13.19 and 13.35%, respectively, and optimum peeling conditions were lye concentration, temperature and peeling time of 8.89%, 100°C and 4.75 min, respectively, for minimum peel loss and unpeeled surface area. The models developed in each case (R-squared of 0.9225 and 0.8428; 0.5929 and 0.8346) were adequate in producing responses as a function of the independent variables. From the optimized values and results obtained, lye peeling was more suitable for sweet potato.

Changes induced by soaking period on the physical properties of maize in the production of Ogi

Abstract This study was aimed at investigating the effect of soaking method and period on some selected physical properties on maize varieties. Five varieties of maize (A4W, C3Y, D8W, B2Y and E9W) were soaked for 12–96 h at ambient temperature of 28 and average hot temperature of 65°C as generally praciticed in the production of Ogi from cereals. Some selected physical properties were evaluated based on a 5 × 2 × 9 factorial design (varieties × soaking methods × soaking periods). The reseult revealed that the linear dimensions of the five varieties of soaked maize increased with increase in linear dimensions up to about 36th hour of soaking. The percentage increase in width was in the range of 5.482–9.67%, 4.064–8.25%, 3.76–6.81% and 0.88–1.81%, for C3Y, B2Y, D8W, A4W and E9W for both soaking conditions, respectively. Significant difference (p < 0.05) existed between the maize varieties for surface area and the volume. These increased with increase in moisture content and soaking period with the highest surface area recorded for maize variety E9W at 36th hours of 65°C. There were significant differences (p < 0.05) between unsoaked and soaked maize varieties for all the samples. Values obtained for sphericity increased with increase in soaking period. There was no significant difference (p > 0.05) in the values obtained for sphericity at soaking condition of 65°C compared with soaking at 28°C. This study showed that the period of soaking had significant effect (p < 0.05) in increasing the overall dimensions of maize grains up to 36th hour and thereafter witnessed an irregular pattern.

Modelling of mechanical properties of five maize varieties at critical processing conditions in the production of fermented slurry-ogi

ABSTRACT This research work was conducted to investigate the impact of critical processing conditions on the selected mechanical properties of maize in the production of fermented ogi slurry. Five varieties of maize (A4W, C3Y, D8W, B2Y, and E9W) were soaked at 28 ºC and average hot soaking at 65ºC, respectively, for 96 h at 12-h interval. Selected mechanical properties were evaluated based on a 5 × 2 × 9 factorial design (varieties× soaking methods× soaking periods). Force (FB) and energy required to break (EB) maize grains decreased significantly (p < 0.05) up to the 12th hour. The EB reduced from 873.3 to 70.0 N mm and from 873.3 to 77.8 N mm for variety E9W at soaking conditions of 28ºC and 65ºC, respectively. Similar trends were observed for other maize varieties. Modulus of elasticity and resilience decreased significantly (p < 0.05) with increase in soaking period and moisture content. The EB to break maize grains was directly proportional to the product of Young’s modulus and area (Em A1.5), the FB and area (Fm A°.5) and force required to break and geometric mean diameter (F Dg2) of maize grains with a high R2 (0.9610.999). This study suggested that the duration of soaking between 12 and 24 h should be enough to significantly (p > 0.05) reduce the hardness, force, and energy required to break whole maize grains in the production of this fermented product and relevant for predicting minimum required energy for a large-scale operation.

Modeling of particle size distribution and energy consumption of wet milled maize at varying soaking period and method in the production of Ogi

ABSTRACT Energy consumptions and particles size distribution of soaked maize grains at varying time were studied and modeled. Rosin–Rammler–Bennet (RRB) model well fitted first milling size distribution with a high coefficient of determination (R2) and low root mean square error (RSME). The milling energy of maize grains decreased significantly (pu2009<u20090.05) with increase in soaking time. The milling energy decrease from 32 to 8.72u2009kWh/kg and 32.00 to 9.00u2009kWh/kg for maize variety E9W at 24th hour soaking conditions of 28 and 65°C, respectively. Similar observations for A4W, B2Y and C3Y at 24u2009h of soaking were recorded. The Work index, Kick’s and Rittinger’s constants decreased with increase in soaking time. There was significant difference (pu2009<u20090.05) in values obtained for Bond work index, Rittinger’s and Kick’s constants; these decreased with increase in soaking time. Predicted energy consumption followed similar trend. The interaction effect between energy consumption, Moisture content, and Milling time showed a high R2 (0.8767–0.99349); while the regressed model for determining energy consumption from relationship between the mass, moisture content, milling time and the ratio of the geometric diameter mean and final size of the product were also established in this work with R2 ranging from 0.9355 to 0.967.