This research characterized flour and raw starches isolated from red and white sweet potato cultivars. Their composition, determined by proximate analysis, is typical of sweet potato cultivars. These cultivars have high amylose content (32-34%) and exhibit a Ca-type X-ray diffraction pattern. Similar gelatinization characteristics were detected for both starches with onset temperature of 67 degrees C and enthalpy of 10.5-11.0 J/g. Starches of both red and white cultivars had well-correlated (r (2) = 0.982) and high solubilization and swelling temperatures, starting at 80 degrees C. Pasting properties of the white cultivar exhibit lower tendency for retrogradation. Water and oil absorption capacities were low for both red and white flours. When parboiled, both cultivars showed improved water absorption capacity and decreased least gelation concentration. It is concluded that the white cultivar should be preferred when low retrogradation tendency is required.

Soy isoflavones, present in many processed soy foods, are known for their phytoestrogenic and antioxidant activities. The aim of this work was to study the kinetics of genistein and daidzein degradation at elevated temperatures and to follow changes in their antioxidant activity. Daidzein and genistein in model solutions (pH 7 and 9) were thermally treated at 120 degrees C or incubated at 70, 80, and 90 degrees C. Isoflavone degradation was observed at all temperatures, with apparent first-order kinetics at 70-90 degrees C, and E(a) = 8.4 and 11.6 kcal/mol at pH 9, respectively. Microcalorimetric stability tests showed a similar pattern of degradation, however, with higher E(a) (genistein, 73.7 kcal/mol; daidzein, 34.1 kcal/mol) that may be attributed to the anaerobic conditions. The antioxidant activity of incubated isoflavone solutions, followed by the ABTS test, decreased rapidly at pH 9 for genistein, whereas only moderate reduction was observed for daidzein (pH 7 and 9) or genistein at pH 7. This may indicate different degradation mechanisms for genistein and daidzein.

The rheological (Pasting, farinograph, and alveograph) properties of wheat flour (WF) replaced with breadfruit four (05–40%) was analyzed. Baking and sensory qualities of the resulting bread were evaluated. Differences in baking properties of loaves produced under laboratory and industrial conditions were analyzed with t‐test, whereas ANOVA was used for other analyses. Peak and final viscosities in the composite blends (CB) ranged from 109.20 to 114.06 RVU and 111.86 to 134.40 RVU, respectively. Dough stability decreased from 9.15 to 0.78 min, whereas farinograph water absorption increased 59.7–65.9%. Alveograph curve configuration ratio increased from 1.27 to 7.39, whereas specific volume (Spv) of the loaves decreased from 2.96 to 1.32 cm3/g. The Spv of WF loaves were not significantly different (P > 0.05) from that of the 5% CB, whereas production conditions had no significant effects on absorbed water (t = 0.532, df = 18 P = 0.3005), weight loss during baking (t = 0.865, df = 18, P = 0.199), and Spv (t = 0.828, df = 14.17, P = 0.211). The sensory qualities of the 5% blend were not significantly different from the WF.

Marble vine (Dioclea reflexa) seed flour was defatted using n-hexane and made into a protein isolate by alkaline solubilization and acid precipitation. The protein isolate was hydrolyzed using alcalase and fractionated into different peptide sizes of <1, 1-3, 3-5 and 5-10 kDa using ultrafiltration membranes. The hydrolysate and its membrane fractions were evaluated for amino acid composition and in vitro antioxidant activities. The results showed that sequential fractionation resulted in higher serine, glutamic acid1glutamine, glycine and tyrosine contents. The 5-10 kDa peptides exhibited significantly (P < 0.05) higher 1,1 diphenyl-1-picryhydradzyl radical scavenging and metal chelation activity when compared to the unfractionated protein hydrolysate and other peptide fractions. Lipid oxidation was significantly (P < 0.05) attenuated by the peptide fractions. We conclude that peptide antioxidant activities were significantly (P < 0.05) improved by membrane fractionation, especially for the <1 kDa and 5-10 kDa fractions. PRACTICAL APPLICATIONSOxidative deterioration of foods, which limits shelf life, increases economic losses and may even lead to formation of toxic compounds which can be prevented using synthetic antioxidants. However, there is increased consumer preference for natural sources of antioxidants. The protein hydrolysate and membrane fractions produced in this work showed antioxidant ability that could make them candidates to replace potentially toxic synthetic antioxidants in foods. Metal chelating ability of the peptides can be used to prevent metal ion-dependent initiation of toxic free radical formation in foods. Incorporation of the peptides into foods will enhance scavenging of toxic free radicals that may form during storage, thereby improving product freshness and longevity. The linoleic acid inhibition potential of the peptides can be used to prevent lipid peroxidation and fatty acid deterioration in foods. Therefore, the Dioclea reflexa seed protein hydrolysates represent good natural sources of antioxidant food preservatives.

Tempe, an Indonesian mold fermented food, was prepared from cowpeas and soybeans using the traditional oriental process with modifications where appropriate. Four complementary foods were developed from whole maize meal or dehydrated fermented maize (ogi) flour fortified with either cowpea tempe or soybean tempe. Wholesomeness and potentials of the vanilla-flavored foods as weaning diets were determined. The nutrient content of all the developed products were within the range prescribed by the FAO/WHO pattern for processed weaning foods. The products had loose bulk densities between 0.40-0.55 g/ml and packed bulk densities between 0.68-0.75 g/ml; reconstitution indexes were between 92.30-104.00 g/ml; viscosities were 34.2-65.0 CP at 70 degrees C and 45.0-76.9 CP at 30 degrees C. Total plate counts ranged from 3.2 x 10(3) - 4.3 x 10(4) cfu/g; coliforms staphylococcus, mold, and yeast were absent in some of the products. The results on sensory attributes showed that tempe-based weaning diets were comparable with Mameal, a commercial product. Maize and maize-fortified diets were slightly higher in packed bulk density. Fortification reduced the viscosity of the diets and the values reduced with increasing temperature. Tempe-based weaning foods reconstituted easily in hot water, while cooking destroyed most of the microorganisms present. Maize-based tempe fortified foods were relatively inexpensive and have potential as weaning foods.

The nutritional quality of food transcends the availability of nutrients in food to being utilizable by the consumer. In this study, a complementary diet for infants was formulated with quality protein maize, soybean protein concentrate, and cassava starch. The formulated diet was extruded and the effect of extrusion on some antinutritional factors and in vitro protein and starch digestibilities of the meals were assessed. The amino acid profile of the samples was determined while other protein quality indices were calculated. The essential amino acid index of the formulated meal ranged from 87.3 in tryptophan to 133.7 in tyrosine-phenylalanine. Protein efficiency ratio of the formulated meal ranged from 1.20 to 2.45. The calculated biological value ranged from 92.57 to 95.20%.Extrusion cooking significantly improved the in vitro protein and starch digestibilities and significantly reduced some antinutritional factors of the formulated meals. Practical applicationsAdequate nutrition during infancy and early childhood is fundamental to the development of each child's full human potential. It is well recognized that the period from birth to 2 years of age is a "critical window" for the promotion of optimal growth, health, and behavioral development. Longitudinal studies have consistently shown that this is the peak age for growth faltering and common childhood illnesses. Nigeria is well endowed with adequate food supplies, however, more than one third of the children under the age of 5 are malnourished and of all deaths of children lower than 5 years of age are directly or indirectly attributable to malnutrition hence the reason for carrying out this study. Foods with balanced amino acid profile can be obtained by mixing legumes and cereal grains. Extrusion cooking utilizes the high temperature short time phenomenon which is effective for the improvement of the biological value of food. K E Y W O R D S amino acid profile, antinutritional factors, complementary diet, essential amino acid, extrusion cooking, in vitro protein digestibility, in vitro starch digestibility, protein quality, quality protein maize, soybean protein concentrate

Summary This study investigated the effect of some preprocessing techniques on the physicochemical and technological properties of pearl millet flour for possible industrial application. Pearl millet was processed into flour using different preprocessing techniques (blanching, debranning, fermentation and malting) and evaluated for physicochemical and functional properties, grain morphology and total viable count. The result showed that fermentation and malting brought about loosening of starch granules. Fermentation significantly reduced the bulk density by 22% and improved the colour lightness and paste viscosity properties of the preprocessed flour. Malting alone resulted in about 50% increase in protein content of the flour with improved solubility up to 64 g/100 g. Total viable count was highest in fermented sample in the order of 108 cfu g−1. Thus, the combination of fermentation and malting would give the best pearl millet flour with improved technological properties for application in the industries, thereby promoting food security in the region.

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