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Hydrothermal processing of gluten-free flours has been shown to enhance their functional and baking properties. Process variables such as temperature, moisture and treatment time conditions were optimised in relation to quality characteristics of acha flour and using a three-variable Box–Behnken design based on response surface methodology. The derived optimal heat-moisture treatment conditions for acha flour were 80 °C, 25% moisture and 17 min, and their effect on proximate and functional properties of acha flour was studied. It was revealed that optimal heat-moisture treatment had minimal impact on the proximate compositions of acha flour but increase water and oil absorption capacities (135% and 90%), swelling power (32%), peak viscosity (8%), pasting temperature (6%) and decreased solubility (9%), breakdown viscosity (9%), setback viscosity (42%) and bulk density (22%). Optimal modified acha flour or was blended with wheat flour at ratios 10:90, 20:80 and 30:70 and utilised in production of bread, and their physical properties and sensory acceptability were studied in relation to their native counterparts and 100% wheat flour. It was revealed that acha flour-wheat flour breads containing optimal heat-moisture treated flours had higher specific volumes and consumer acceptability scores, and more open crumb structures than those of their native acha counterparts regardless of inclusion level. Ratio 10:90 of optimal heat-moisture treated flour and wheat flour produced bread with properties closest to 100% wheat flour bread. Thus, the derived optimal heat-moisture treatment conditions were successful in enhancing the functional and baking properties of acha. Findings from this study will be of relevance to the flour mills and the baking industry as well as will enhance knowledge on the baking prospects of hydrothermal treatment and acha flour properties.

Sushi rice is a ready-to-eat traditional Japanese dish seasoned with vinegar, sugar and salt that has gained popularity worldwide. There are many rice cultivars grown in the world which vary in their cooking, sensory, and processing quality. The aim of this study was to analyse chemical, physical, and functional properties of three rice varieties (Vietnamese, Italian, and Australian) to determine their suitability for sushi rice production. Rice was cooked using industry norms and vinegar was then added; samples with no vinegar were prepared for comparison. The rice was stored during 5 days at 4 °C after cooking for texture profile analysis and samples were taken on day 1 and day 5. Flour composition as well as amylose content, gelatinisation properties using differential scanning calorimeter, pasting properties using Rapid Visco Analyser, water absorption capacity (WAC), oil absorption capacity (OAC) and swelling power of extracted starch were determined. Results showed that the amylose content (16.51 to 21.37%) had a large impact on the functional and quality characteristics of the rice variants including texture, pasting, gelatinisation and WAC properties. Australian starch showed the highest amylose content, setback viscosity, final viscosity, pasting temperature and lowest gelatinisation temperature. The lower amylose content and gelatinisation temperature contributed to a softer texture in the Vietnamese rice samples over life. The added vinegar aided in keeping the texture soft during the shelf-life of the rice. Since sushi rice is usually prepared with vinegar, Italian and Vietnamese rice are better candidates for sushi rice based on their lower hardness after 5 days of storage when compared to the Australian variety.

In the accompanying paper (Part 1), it was reported that forced convection roasting of wheat before milling can be directed to tailor the viscosifying properties of flour. The objective of the present work was to examine the effect of prior wheat roasting on flour proteins. Effective control of wheat roasting conditions proved to be essential to avoid the irreversible loss of flour functionality as deduced from the flour ethanol and lactic acid solvent retention capacity and mixography data. Response surface models predicted roasting at 108°C and 80 Hz (135 s) to maintain protein integrity. The microstructure of flour and isolated starch as well as X‐ray diffraction patterns revealed starch to be relatively unaffected by this heat treatment. Flour produced from roasted wheat can still be used for products that require the formation of a gluten network. Protein is more sensitive to roasting conditions than starch.

Dry thermal treatment of wheat modifies the properties of wheat and of flour prepared from it. The objective of this study was to investigate the effect of wheat roasting on microstructural properties of wheat grains using confocal laser scanning, X‐ray diffraction (XRD), and scanning electron microscopy (SEM) techniques. The impact of roasting on the damaged starch contents, the solvent retention capacity profiles, and the pasting properties of the resulting flour prepared from roasted wheat were also studied. Response surface models predicted wheat roasting at 115°C and 65 Hz (165 s) to enhance flour viscosifying properties. Roasting before milling resulted in grain puffing, slight damage to the starch granule surface, and destruction of the protein matrix, as observed using SEM. XRD analysis revealed that amylose–lipid complexation had occurred. As a result of roasting, the peak, hot paste, and final viscosities of flour from roasted wheat were significantly (p≤ .05) higher than those of flour produced from control wheat. Roasting induces structural changes in wheat. Flour produced from roasted wheat can be used to produce gel structures with increased viscosities. Dry thermal treatment improves the viscosifying properties of flour milled from roasted wheat.

•This study produced poundo yam from white yam supplemented with cassava flour.•Carbohydrate (80.83–85.33%) was the major nutrient in the flour & their composites.•Composite flours were more dispersible & showed increased ability to absorb water.•Composite flour had increased breakdown, final, peak & setback viscosities.•Addition of cassava flour produced dough that were firmer, stickier and gummier.

•A total of 45 volatile metabolites were found in the cooked pasta samples.•Similar (8) metabolites were observed across the four pasta samples.•Esters were the major metabolites found in the pasta samples.•All the pasta showed the presence of nutritionally important metabolites.•Fractionation prior to pasta making can distribute metabolites within pasta fractions.

Bambara groundnuts (Vigna subterranea) are a good source of starch that may be potentially used for various industrial applications. The effect of microwave heating time (0, 10, 30 and 60 s) on the physicochemical and functional properties of Bambara groundnut starch was investigated. Native and microwaved Bambara groundnut showed the A-type crystallinity pattern. However, there was a decrease in the relative crystallinity of the starch after microwaving. Microscopically, the native starch granules were smooth but had pinholes after microwaving. Microwaving resulted in significant (p ≤ 0.05) reduction in peak viscosity, hot paste viscosity, cold paste viscosity, pasting temperature and set back ratio. The swelling power of Bambara groundnut starch similarly decreased with increasing microwaving time. Microwave heating led to a shift in the gelatinization range to higher temperatures. However, the enthalpy of gelatinization decreased after microwaving. Short microwaving times (≤60 s) were sufficient to cause significant improvement in the pasting and thermal properties of Bambara groundnut starch. Microwaved Bambara groundnut starch with reduced swelling can be potentially used in food products that do not require high swelling such as noodles.

•Onion had higher (almost double) phenolic content (57.36 mg GAE/g) than garlic extract.•Flavonoid content (69.57 mg RE/ml) of onion extract was almost triple that of the garlic.•Both extracts reduced the growth of all tested organisms except the Enterobacteriaceae.•Gram +ve bacteria were more susceptible to onion & garlic extracts than Gram -ve strains.

There is an increase in the use of adoptable bioprocessing methods for the development of high-quality pulse ingredients. This study investigated the nutritional composition, physicochemical, bioactivity, in vitrodigestibility, functional, pasting, thermal and colour characteristics of germinated (24–72 h) pigeon pea. Germination increased (p ≤ 0.05) protein, dietary fiber, calcium, iron, zinc, vitamins B, vitamin C (1.25–8.46 mg/100 g), resistant starch, protein digestibility (72.30–82.66 g/100 g), total phenolic content, antioxidant activities and most amino acids. Phytic acid, tannin and trypsin inhibitor activity decreased significantly during germination. Germination also increased water absorption capacity, protein solubility, foaming capacity, emulsion stability and activity of the flours while bulk density decreased. Functional, pasting, thermal and color, properties of pigeon pea was modified following germination. This study demonstrated that short-term germination is a natural means for the development of functional pigeon pea flour to promote its application in the food industry.

Flour-additive complexes exhibit noteworthy characteristics which can be exploited in food applications. In this study, food additives namely guar gum (GG) and sodium stearoyl lactylate (SSL) were respectively complexed with cassava flour (CF) using dry-heat-moisture treatment and steam-heat-moisture treatment, respectively. Thus, the effect of the complexation processes on structural, functional, viscoelastic and thermal characteristics of CF were examined. It was revealed that all the complexation processes increased granule deformity and decreased granule size (d[4.3]; 48%–73%), as well as increased relative crystallinity (5%–19%), gelatinisation onset to conclusion temperature range (22%–51%) and gelatinisation enthalpy (ΔH; 23%–36%) of CF. All the complexation processes also decreased the swelling characteristics (swelling power and peak viscosity) and amylose retrogradation tendency (setback viscosity; 43%–64%) of CF. Furthermore, irrespective of heat-moisture treatment, CF-SSL complexes exhibited larger d[4.3]and greater paste and gel resistance to structural deformation and relative crystallinities than CF-GG complexes. It was also deduced that heat-moisture treatment had contrasting effects on the characteristics of the CF-additive complexes. Thus, the heat-moisture treated CF-additive complexes presented in this study can be used as structuring agents in food systems.

Amahewuis a traditional fermented beverage made from white maize that is widely consumed in South Africa. In this study, amahewuwas prepared from provitamin A-biofortified maize (PBM) and different inocula and the nutritional properties of the beverage were assessed using standard methods. The amahewusamples were prepared by fermenting maize porridge using lactobacillusstarter culture (LSC), wheat bran (WB) and malted provitamin A maize (MM) together with either MM or WB. The inoculum types did not substantially influence the overall composition of amahewu. Carbohydrate (82%) followed by protein (12%) were the major nutrients in all samples. However, inoculating amahewubeverage with LSC substantially reduced the fermentation time. Iron, zinc, and lysine contents increased slightly after fermentation, especially in the sample with added LSC. Protein digestibilities of amahewusamples also increased slightly after fermentation. The β-carotene contents (approx. 1.8 μg/g) were very similar across amahewusamples and these were substantially retained after fermentation. Hence, PBM may be a better alternative to white maize for the preparation of amahewubeverage with improved nutritional quality.

The physicochemical properties of starch extracted from fermented cassava roots was studied. Starches extracted from fermented cassava roots showed slightly lower amylose contents (24–26%) compared to starch extracted from unfermented cassava roots (27%). Fermented starches had partly broken granule with fissures or micro-holes and rougher surfaces with various starch granules clumping together. Fermentation resulted in significant reduction in the swelling power of cassava starch. Fermentation of cassava roots significantly (p ≤ 0.05) increased the onset, peak and conclusion gelatinization temperatures of starches. Pasting properties of cassava starch were significantly (p ≤ 0.05) affected by fermentation. Peak and breakdown viscosities decreased after fermentation, but the final and setback viscosities increased. However, fermentation of the cassava roots did not result in any significant changes (p > 0.05) on the pasting temperature and peak time of the starches. Fermentation of cassava roots prior to starch extraction can be used to produce modified starch, which can be used in various baking applications.