Rheological behaviour, physical and sensory properties of orange fleshed sweet potato and soy concentrate bread.

Trends on the use of non-wheat flours for bread production has led to researches on improving the rheological characteristics of such non-wheat flours. This aim of this study was to determine the effect of soy concentrate on the protein and rheological behaviour (pasting and mixolab) of the orange-fleshed sweet potato composite flour as well as the physical and sensory qualities of the bread produced. The experimental design to obtain the optimum blends was carried out using optimum design of response surface methodology; with sweat potato, soy bean concentrate, date palm flour and potato starch as the independent variables. The result shows that protein values ranged from 6.19 to 21.10%, carotenoid values ranged from 0.11 to 26.18 mg/100 g. pasting temperature ranged from 68.50 to 82.33 °C; peak viscosity ranged between 159 and 1040 RVU, the breakdown value ranged between 24 and 272 RVU and the setback value ranged from 75 to 368 RVU. The bread loaf weights ranged from 111 to 256 g and the specific loaf volume ranged from 0.7 to 1.6cm3/g. The bread samples varied significantly (p < 0.05)  with the consumer's acceptability in terms of aroma, appearance, taste and overall acceptability. It was observed that soy-concentrate increase the protein content and improves rheological properties of the composite flour for the production of gluten free bread.

Biochemical and antioxidant properties of cream and orange-fleshed sweet potato.

The rate of micronutrient deficiency has been on an increase since the last decade and the utilization of bio-fortified crops could help to alleviate this deficiency and food insecurity in Africa especially in Nigeria. The aim of this study was to compare the biochemical and antioxidant properties of cream-fleshed and orange-fleshed sweet potato. The varieties of OFSP used in this study were mother's delight (MDP) and king J (KJP) orange-fleshed sweet potato while the other variety was cream-fleshed sweet potato (CFSP). The tubers were processed into flour and analyzed for proximate, minerals, anti-nutrient and antioxidant properties using standard methods. The ash content ranged from 4.60 to 7.20%, carbohydrate content ranged between 73.47 and 78.61%. MDP has the highest beta carotene content with 18.83 mg/100g followed by KJP and CFSP. Magnesium value ranged between 124.0 and 148.2 mg/100g, potassium ranged from 1226.5 to 2350.0 mg/100g. Sodium-potassium ratio (Na/K) was <1. The antioxidants properties evaluated were all higher in OFSP than CFSP. The bio-fortified sweet potato showed an improved biochemical and antioxidant properties compared to the CFSP, thus OFSP will be suitable to combat micronutrient deficiency and food insecurity in Africa.

Orange-fleshed sweet potatoes composite bread: A good carrier of beta (ß)-carotene and antioxidant properties.

Orange-fleshed sweet potato (OFSP) is one of the unique varieties of sweet potatoes tuber that has attracted food professionals due to its great health benefits. This study investigates into ß-carotene and antioxidant properties of OFSP composite bread. Random Surface Methodology was used for the experimental design. Analysis carried out on the bread includes antioxidant activity, alpha-amylase, and alpha-glycosidase inhibitory activity, protein & ß-carotene retention/losses, glycemic index, and sensory evaluation. Total phenol ranged from 7.32 to 21.93 mg GAE/g, total flavonoid ranged between 6.12 and 13.20 mg QE/g and FRAP ranged from 12.31 to 40.36 mg AEE/g. The estimated glycemic index ranged from 51.42% to 72.80%. The value of ß-carotene before and after processing ranged from 15.4 to 39.1 mg/100 g and 8.9 to 18.4 mg/100 g, respectively. OFSP composite bread has high antioxidant potential and may be used as functional foods. PRACTICAL APPLICATIONS: Orange-fleshed sweet potatoes (OFSP) is a novel variety of sweet potatoes that have been sight-saw to owe numerous health benefits in terms of vitamins, minerals, ß-carotene, antioxidants but it is low in protein. Incorporation of plant protein will help to increase its protein content and enhance its utilization in confectionery industries as a good carrier for antioxidants and other health benefits components.

Physicochemical evaluation and Fourier transform infrared spectroscopy characterization of quality protein maize starch subjected to different modifications.

Quality protein maize (QPM) is a biofortified maize rich in lysine and tryptophan, essential amino acids required in human nutrition. This research therefore characterizes native and modified starches from QPM by evaluating the physicochemical properties, Fourier transform infrared spectra (FTIR), and pasting properties. The native QPM starch was modified by oxidation, acetylation, pregelatinization, and acid thinning techniques. The starch yield of native QPM was 43.80%, while that of modified starches were from 88.22 to 98.34%. The moisture content of the native and modified starches was from 4.56 to 9.20 g/100g. Modifications significantly (P ≤ 0.05) reduced the lipid, protein, and amylose contents of the QPM. While the native starch had 0.72 g/cm3 bulk density, modified starches were between 0.59 and 0.88 g/cm3 ; chemical modification reduced the bulk density and physical modification increased it. In addition, all the modifications except oxidation significantly (P ≤ 0.05) increased water absorption capacity. The oil absorption of the starch samples was increased by modification techniques used with the exception of physical modification. Chemical modification reduced the viscosity of QPM starch while physical modification increased it. The reducing sugar content of the starch was reduced by both the physical and chemical starch modification techniques. Acetylated sample exhibited the highest swelling power while acid-thinned sample had the least. The major functional groups identified via FTIR were OH, C-H, C=H, and C≡H. Modifications did not affect the functional groups as all the native and modified starches (except oxidized sample) all have similar spectrum and bands stretch. PRACTICAL APPLICATION: The study contributes to existing knowledge on valorization of modified starch from quality protein maize. Profiling the chemical attributes of modified starches is especially valuable in novel food processing techniques.

Development and evaluation of extruded ready-to-eat snack from optimized rice, kersting's groundnut and lemon pomace composite flours.

Composite flour comprising rice, kersting's groundnut and lemon pomace were produced. The percentage blends of the composite flours based on the proximate composition and functional properties were optimized using optimal mixture design of response surface methodology (RSM). The optimum blends were subjected to further analyses (pasting properties and Mixolab). The overall best blend was selected for extrusion. The extrusion process was optimized using central composite design of RSM. The variables were moisture content, screw speed and temperature while the dependent variables were lateral expansion, residence time, throughputs, water absorption index and water solubility index. The microbial analysis as well as the sensory evaluation of the extrudates was also evaluated. The result showed that addition of kersting's groundnut had positive effect on the protein content while lemon pomace had positive effect on both fibre and protein contents. Blend with highest rice flour had the best pasting properties. The Mixolab results had C1 stage similar to wheat flour while it had no C2-C5 stages. The optimum blend for extrusion was 97 °C barrel temperature 12% moisture and 90 rpm screw speed which present the best lateral expansion, water absorption index and water solubility index. All the snacks had high general acceptability.

Quantitative and qualitative characterization of mango kernel seed oil extracted using supercritical CO2 and solvent extraction techniques.

Characterization of mango kernel seed oil extracted using supercritical CO2 (SC-CO2) and conventional solvent (hexane, petroleum ether, ethanol and acetone) extraction techniques was carried out using differential scanning calorimetry (DSC), Fourier-transform infrared spectroscopy (FTIR), Gas chromatography mass spectroscopy (GC-MS) and fluorescence microscope. The extractor and separator temperatures of the SC-CO2 were 60 and 50 °C respectively while the pressure was varied from 35 to 40 MPa. Solvent extractions were maintained at the boiling points of the various solvents. The results indicated that solvent extraction had higher yields (8.02-19.88%) while SC-CO2 had a lower yield (2.5-3.6 %); the yield of conventional solvent extraction increased with decreasing particle sizes. Ethanol extracted oil had lowest enthalpies of endothermic reaction (1.17-2.74 J/g); while other solvents were between 42.54 and 45.64 J/g with SC-CO2 having 37.40 J/g. The melting points for ethanol extracted oil were 7.34 and 35.20 °C; other solvents ranged between 13.39 and 15.15 °C while, SC-CO2 was 35.05 °C. SC-CO2 extracted oil had no crystallization parameter, while conventional solvent extracted oil with the exception of ethanol were between -33.23 and -33.97 J/g. The FTIR showed that CH3, CH2 and COH were the predominant functional groups in hexane, petroleum ether, acetone and SC-CO2-extracted oil; ethanol extracted oil had -OH and CH2. The extracted oil using solvent extraction technique was higher in unsaturated fatty acid (UFA) with the exception of acetone extracted oil. SC-CO2 extracted oil had higher saturated fatty acid (SFA) content (47.01%). The predominant UFA and SFA were oleic acid stearic acid.

Optimization of the functional characteristics, pasting and rheological properties of pearl millet-based composite flour.

Optimisation of composite flour comprising pearl millet, kidney beans and tigernut with xanthan gum was evaluated for rheological evaluations. The functional properties of the composite flour were optimized using optimal design of response surface methodology. The optimum blends, defined as blends with overall best functional characteristics were run 3 (75.956% pearl millet, 17.692% kidney beans, 6.352% tigernut flours), run 7 (85.000% pearl millet, 10.000% kidney beans, 5.000% tigernut flours) and run 13 (75.000% pearl millet, 20.000% kidney beans, 5.000% tigernut flours). The pasting characteristics and rheological evaluation of the optimized blends were further evaluated in rapid visco units (RVU). Run 7 had the overall best pasting characteristics; peak viscosity (462 RVU), trough (442 RVU), breakdown viscosity (20 RVU), final viscosity (975 RVU), setback (533 RVU), peak time (5.47 min) and pasting temperature (89.60 °C). These values were found to be better than several composite flours consisting mixture of wheat and non-wheat crops. In addition, the rheological characteristics (measured by Mixolab) showed that run 7 is the best in terms of dough stability, swelling, water absorption and shelf stability. Composite flour with 85% pearl millet flour in addition to kidney beans and tigernut flours could therefore serve as a viable alternative to 100% wheat flour in bread production.

Antioxidant, functional and rheological properties of optimized composite flour, consisting wheat and amaranth seed, brewers' spent grain and apple pomace.

Consumer's interest in functional food has continued to increase due to its potential health benefits. This study therefore is aimed at developing a functional wheat based flour comprising, amaranth (Amaranthus hypochondriacus) seed, brewers' spent grain and apple pomace. The statistical analyses were carried out using response surface methodology (RSM). For the experimental design, the composite flour components were the variables while the proximate and mineral compositions were the responses. After the statistical optimisation process, the best three blends were chosen for further analyses; determination of antioxidant, functional and rheological properties. From the results, the best blends were Runs 11, 13 and 19, with percentages composition of wheat, amaranth seed, brewers, spent grain and apple pomace of 65 %, 30 %, 2 %, 3 %; 60.43 %, 29.68 %, 4.1 %, 5.79 % and 81.94 %, 6.75 %, 3.39 %, 7.92 % respectively. The ANOVA, R(2) and R(2) adjusted values for the proximate and mineral compositions showed that the composite flours were statistically satisfactory. The results also indicated that the antioxidant, functional and rheological properties of the three best blends showed good and acceptable nutritional and rheological properties. Composite flours with acceptable and excellent nutritional composition, functional properties and rheological behaviour can be obtained from composite blends consisting wheat, amaranth seed, brewers, spent grain and apple pomace flours.