QUALITY ATTRIBUTES OF PANCAKES FROM PEELED AND UNPEELED SWEETPOTATO FLOURS WITH CASSAVA STARCH

This study evaluated some quality attributes of pancakes from peeled and unpeeled sweetpotato flours and cassava starch. Cassava starch was substituted up to 30% of the total composite flour. The proximate composition, colour, carotenoid and functional properties of the different flour blends were determined. The flour blends were processed into pancakes and the proximate composition and sensory acceptability of the pancakes were determined. Data obtained were subjected to analysis of variance. The result showed that they were significant differences (p<0.05) in the functional properties of the flour blends. Bulk density, Water absorption capacity, Oil absorption capacity, swelling capacity ranged from 0.70 to 0.78 g/ml, 1.87 to 2.30 g/ml, 1.02 to 1.40 g/ml and 5.18% to 6.66%  respectively. There were significant differences (p<0.05) in the proximate composition of the pancake samples. The values ranged from 42.76 to 45.53%, 2.13 to 3.98%, 9.06 to 10.34%, 5.01 to 7.18%, 3.75 to 6.01% and 29.19 to 35.33% for moisture, ash, fat, protein, crude fibre and carbohydrate contents, respectively. Pancake produced from 100:0 peeled and unpeeled sweetpotato flour had the highest score for overall acceptability which can compare favorably, with pancakes from wheat flour which is the control sample. In conclusion, sweetpotato flour blended with cassava starch at different ratio gave good proximate and functional properties which resulted in pancakes of good quality attributes.   &nbsp

Effect of frying treatments on texture and colour parameters of deep fat fried yellow fleshed cassava chips

Effects of frying treatments on texture (hardness) and colour parameters (L, a, b, Delta) during deep fat frying of yellowfleshed cassava root slices (TMS 01/1371) were investigated. Slices (dimension of 40mm × 25mm × 3 mm) were divided into three portions and subjected to vacuum frying (fresh slices) and atmospheric frying (fresh and predried slices) and equivalent thermal driving forces (ETDF) of 60∘C, 70∘C, and 80∘C were maintained during frying. The quality attributes investigated were best preserved in vacuum fried chips. The overall colour change in chips fried under vacuum conditions at 118∘C and 8 min was the least (21.20) compared to fresh and atmospherically predried ones (16.69 and 14.81, resp.). A sharp reduction in the breaking force was obtained for all frying treatments after 8 min and this effect was the least in vacuum fried chips. First-order kinetics modeled the changes in quality attributes for all the temperatures investigated. Rate constants k (min−1) obtained for vacuum frying were almost equal to that of atmospheric frying while activation energies for hardness and colour change were 53.30 and 467.11 KJ/mol, respectively. Quality attributes studied were best preserved during vacuum frying

Adsorption isotherms and thermodynamics properties of water yam flour

Adsorption isotherms of water yam flour were determined by static gravimetric method of saturated salt solutions in the range of water activities between 0.11 and 0.96 and at temperatures of 25, 35 and 45 °C. The experimental sorption data was fitted to five models: Guggenheim-Anderson-De Boer (GAB), Peleg, Iglesias-Chirife, Exponential and Oswin and the differential enthalpy and entropies were determined. Equilibrium moisture contents decreased with increase in temperature at all the water activities studied. Peleg model gave the best fit for the sorption isotherm of water yam flour. Monolayer moisture content values estimated from the GAB-model were found to decrease with increases in temperature. The differential enthalpy and entropy decreased with increases in moisture content. The isokinetic temperature was 371.32 K and the compensation theory was satisfied

Mineral and antinutrient content of high quality cassava-tigernut composite flour extruded snack

This study investigated the mineral and antinutrient composition of extruded snack produced from different blends of high quality cassava and tigernut flour. The extruded snacks were produced using a single-screw laboratory extruder at constant feed moisture (27%), screw speed (60 rpm) and barrel temperature (80C). It was observed that the extrudates had higher values for mineral composition (phosphorus, calcium, magnesium, potassium and iron) than the composite flour which showed that extrusion cooking improves the absorption of the minerals. The antinutrient (tannin, phytate, saponin, oxalate, alkaloids and total phenolic) contents of all the flour blends significantly (P < 0.05) increased with tigernut flour inclusion. Extrusion cooking resulted in significant (P < 0.05) reduction in the antinutrients of the extrudates. The study showed that extrusion cooking reduced the antinutritional factors thereby increasing the bioavailabilty of minerals. Also, the minerals were not affected by the extrusion cooking process probably because minerals are heat stable

Effect of species, pretreatments, and drying methods on the functional and pasting properties of high-quality yam flour

The study investigated the functional properties of HQYF (high-quality yam flour) from tubers of four dioscorea species. The tubers were processed into HQYF using two pretreatments (potassium metabisulphite: 0.28%, 15 min; blanching: 70°C, 15 min) and drying methods (cabinet: 60°C, 48 h; sun drying: 3 days). Significant differences (P < 0.05) were observed in pasting characteristics of flours among the four species. The drying method significantly affected only the peak viscosity. The interactive effect of species, pretreatment, and drying methods on the functional properties was significant (P < 0.05) except for emulsification capacity, angle of repose, and least gelation concentration. The significant variation observed in most of the functional properties of the HQYF could contribute significantly to breeding programs of the yam species for diverse food applications. The pastes of flour from Dioscorea dumetorum pretreated with potassium metabisulphite and dried under a cabinet dryer were stable compared to other samples, hence will have better applications in products requiring lower retrogradation during freeze/thaw cycles

Optimization of some processing parameters and quality attributes of fried snacks from blends of wheat flour and brewers' spent cassava flour

The effect of some processing parameters (frying temperature [140–160°C], frying time [2–4 min], level of brewers' spent cassava flour (BSCF) [20–40%], and thickness [2–4 mm]) on some quality attributes of wheat-BSCF fried snack was investigated. Response surface methodology based on Box–Behnken design was used to optimize the effect of process parameters on product quality. Sensory evaluation of the optimized sample to determine its level of acceptability was carried out as well as the comparison with fried snack from 100% wheat flour. Increasing temperature had significant (P < 0.05) negative effect on the texture. Based on the desirability (0.771) concept, a frying temperature of 140 °C, frying time of 4 min, 32% level of BSCF, and 2 mm thickness was obtained as the optimized conditions. Sensory analyses showed that the optimized sample was preferred in terms of texture and its oiliness to fried snack prepared from 100% wheat flour, but, the aroma, taste and appearance of the wheat snack were preferred

Effect of Frying Treatments on Texture and Colour Parameters of Deep Fat Fried Yellow Fleshed Cassava Chips

Effects of frying treatments on texture (hardness) and colour parameters ( , , , Δ ) during deep fat frying of yellow fleshed cassava root slices (TMS 01/1371) were investigated. Slices (dimension of 40 mm × 25 mm × 3 mm) were divided into three portions and subjected to vacuum frying (fresh slices) and atmospheric frying (fresh and predried slices) and equivalent thermal driving forces (ETDF) of 60 ∘ C, 70 ∘ C, and 80 ∘ C were maintained during frying. The quality attributes investigated were best preserved in vacuum fried chips. The overall colour change in chips fried under vacuum conditions at 118 ∘ C and 8 min was the least (21.20) compared to fresh and atmospherically predried ones (16.69 and 14.81, resp.). A sharp reduction in the breaking force was obtained for all frying treatments after 8 min and this effect was the least in vacuum fried chips. First-order kinetics modeled the changes in quality attributes for all the temperatures investigated. Rate constants (min −1 ) obtained for vacuum frying were almost equal to that of atmospheric frying while activation energies for hardness and colour change were 53.30 and 467.11 KJ/mol, respectively. Quality attributes studied were best preserved during vacuum frying

Production and quality evaluation of extruded snack from blends of bambara groundnut flour, cassava starch, and corn bran flour

Protein dense, fiber-rich extruded snacks were produced from blend of bambara groundnut flour, cassava starch, and corn bran flour using a single screw cooking extruder. The snacks were analyzed for their physical properties and proximate composition using standard laboratory procedures. The expansion ratio, specific volume, breaking force, and breaking strength index (BSI) of the snacks ranged from 0.85 to 1.22, 0.75 to 1.30 g/cm3, 3.95 to 36.45 N, and 0.99 to 9.11 N/mm, respectively. The breaking force and BSI were high and increased at increasing levels of cassava starch and corn bran inclusion. Moisture, protein, fat, carbohydrates, crude fiber, and total dietary fiber contents of the snacks were 5.40–10.80, 3.26–17.62, 0.68–10.35%, 60.56–85.03, 0.32–4.78, and 7.36–28.74%, respectively. The study revealed a great potential of obtaining a nutrient dense extruded snack from underutilized plant commodity (bambara groundnut) and waste from corn milling (corn bran)

Performance evaluation of downdraft gasifiers under various conditions

This research studied the effect of biomass types and moisture content on the performance of a downdraft gasifier. Sawdust, woodchip and bean chaff were used as test samples at three moisture contents (10, 20 and 30% w.b) which was determined with oven drying method and Pascal’s manometric tube was prepared to measure the quantity of methane, hydrogen sulfide, carbon dioxide and carbon monoxide in the syngas. The gas obtained at 10% moisture content for the three biomass after gasification was analyzed and compared to standard values. Ash content, gasification time and temperature were measured using standard methods. The ash contents at 10, 20 and 30% moisture contents for wood chips, sawdust and bean chaff were 0.210, 0.457, 0.750kg, 0.202, 0.290, 0.651kg and 0.295, 0.228, 0.394kg respectively. The gas samples were taken at 10% moisture for analysis because it produced the lowest ash content. Gas produced at 10% moisture content showed that methane, CO2 and H2S contents for wood chips; sawdust and bean chaff were 60.85, 27.50, 0.44%; 62.33, 23.77, 0.87% and 63.94, 18.91, 0.58% respectively. The values of CO was insignificant. The moisture content of the biomass significantly (p < 0.05) affected the values of ash content, gasification time and temperature but the effects of biomass types were not significant. Ash content and gasification time increased with increase in moisture level with the least value of 0.210 kg and 61 minutes at 10% moisture content respectively. The gasification temperature decreased as moisture level increased and vice versa. Increase in moisture level increased the ash content and gasification time. The higher the gasification temperature, the lower the time. Gasifier efficiency was also affected by moisture content and biomass types. The best gasifier efficiency was observed at 10% moisture content with 60, 57 and 75% for sawdust, woodchips and bean chaff respectively

Development of small-scale downdraft gasifiers for biomass gasification

Biomass gasification mainly involves a process whereby agricultural residues or biomass are subjected to partial combustion for the biomass to undergo pyrolysis and reduction, thereby releasing its gaseous component such as hydrogen, carbon-dioxide and methane. Past studies have laid emphasis on the need to study the effect of moisture content and biomass types on the rate of gasification and gasifier efficiency. This study focused on the development of a downdraft gasifier for production of syngas using agricultural wastes as raw materials. The design of the Imbert type downdraft gasifier was based on specific gasification rate, called hearth load Gh, nozzle air blast velocities, throat inclination angle, air inlet diameter and size of reduction zone. The developed gasifier consisted of a reactor, cyclone and filtration unit of 0.006, 0.016, and 0.006 m3 capacities respectively. The testing and evaluation of the designed gasifier showed adequate capacity for biomass treatment by pyrolysis. The fabricated gasifier also showed high efficiency in the pyrolysis of the selected biomasses and the product yields are appreciable. The development and use of such gasifier especially for the treatment of other agricultural wastes is hereby solicited