Phenolic compounds in cowpea and horse gram flours in comparison to chickpea flour: Evaluation of their antioxidant and enzyme inhibitory properties associated with hyperglycemia and hypertension

Evaluation of phenolic contents and their in vitro bioactive functional properties of cowpea and horse gram flours in comparison to chickpea flour revealed that horse gram flour, which contain highest concentrations of total phenolics and total flavonoids was found to be the most active 2,2′-diphenyl-1-picrylhydrazyl (DPPH) radical scavenger. Hydrogen peroxide scavenging capacity, reducing power and metal chelating abilities were significantly higher in cowpea and horse gram than chickpea flour. Phenolic extracts from flours showed distinct variations in the inhibition of enzymes associated with hyperglycemia and hypertension. Although, α-glucosidase inhibitory activity was superior in cowpea (IC₅₀ 52.8 μg/ml), α-amylase (IC₅₀ 96.4 μg/ml) and angiotensin-I converting enzyme (IC₅₀ 32.8 μg/ml) inhibitory activities were predominant in horse gram. These results provided useful information for effective utilisation of legume flours as ingredients in composite flours and for the development of food products with health promoting functions.     

Nutritional implications and flour functionality of popped/expanded horse gram

Utilization of horse gram and its flour in legume composite flours and products is limited due to the presence of antinutritional components, poor functional and expansion properties. Enzymatic treatment was used to improve the expansion and functional properties of horse gram to facilitate its use as an ingredient in food processing. Xylanase-mediated depolymerization of cell wall polysaccharides of horse gram lead to the development of a new expanded/popped horse gram. Expansion process of enzyme treated horse gram resulted in increased length (5.3–6.8 mm) and higher yield of expanded grains (63–98%). The expanded horse gram had lower bulk density, higher protein digestibility and more resistant starch compared to the control raw grains. Dietary fibre content of raw and processed horse gram was in the range of 14.57–16.14%. High temperature short time (HTST) conditions used during expansion process lowered the levels of phytic acid, tannins and protease inhibitors by 46%, 61% and 92%, respectively. The flour obtained from xylanase treated and expanded horse gram had higher water (204.3 g/100 g) and oil absorption capacities (98.4 g/100 g) than unprocessed flour, which had 135.8 g/100 g and 74.6 g/100 g, respectively at ambient conditions. There was a decrease in foaming capacity and foam stability in expanded gram flour. However, emulsion stability increased significantly in the processed samples. Thus, the study indicated that nutritional value and flour functionality of horse gram could be improved by processing it into a new expanded product that can be used as an ingredient in food processing.     

Wheat flour proteins: isolation and functionality of gliadin and HMW-glutenin enriched fractions

The amount of glutenin subunits of high molecular weight (HMW-glutenins) appears to be closely related to breadmaking. The relationship of their specific functional properties and gluten quality has not been demonstrated. The difficulty in isolating non-denatured HMW-glutenins explains largely the lack of information. Investigations have been conducted to isolate HMW-glutenins without using denaturing agents such as SDS or urea. Using wholemeal treated in mild reducing conditions with Na₂SO₃, the procedure uses solubilisation in hot aqueous ethanol with the subsequent specific precipitation of HMW-glutenins at low temperature. Proteins present in the various extracts were anlaysed by SDS-PAGE and reverse-phase HPLC. The HMW-glutenins were obtained by precipitation at low temperature from ethanol extract (purification factor ∽12), whereas the supernatant mainly contained gliadins and LMW-glutenins. After addition of these fractions to meal the modifications of the rheological properties of the resulting dough were investigated. A model explaining the participation of the different fractions to the structure and the solubility of gluten is suggested. © 1998 Society of Chemical Industry.     

Wet separation of wheat flours into starch and gluten fractions: the combined effects of water to flour ratio–dough maturation time and the effects of flour aging and ascorbic acid addition

The process of making a dough, allowing time for maturation, dispersing the dough in water and wet sieving/washing to obtain a protein fraction and starch milk was studied using response surface methodology by changing the water to flour ratio in dough making (400–710 g kg^?1), maturation time (45–660 s) and the type of flour. Two grades of bread wheat flour and durum clear flour were studied. The effects of aging at ambient temperature for up to 29 days and the addition of ascorbic acid at 100 or 500 mg kg^?1 flour on separation behaviour were also studied for freshly milled high‐grade (65% extraction) bread wheat flours at constant maturation time, 600 s, and at optimum farinograph water absorption value. The quantities and dry matter contents of the protein fraction and starch milk were measured; a sample of starch milk was centrifuged to obtain decantate, tailings and prime starch fractions, and the dry matter contents of each were determined. All the dried samples were also analysed for protein content. The fractional recoveries of dry matter and protein in the protein fraction, prime starch, tailings and decantate were calculated for each experiment. The acid values of flour oils were also determined on some aged flour samples. The results indicated superior separation characteristics in high‐grade wheat flour compared with lower‐grade flours. The water to flour ratio was more influential than maturation time within the range studied. Contrary to the initial expectation, no statistically significant effect of flour aging was observed in the studies with no additive, and ascorbic acid addition was not found to improve the wet separation behaviour, the separation behaviour becoming even worse at the 100 mg kg^?1 level. Acid value showed a slight increase with time. © 2002 Society of Chemical Industry     

Separation of bread wheat flours into starch and gluten fractions: effect of water temperature alone or in combination with water to flour ratio

Two different commercial bread wheat flours (BF‐I, 65% extraction and BF‐V, 86% extraction) were separated into gluten and starch milk by making a dough, allowing some time for maturation, dispersing the dough in water and wet sieving/washing. The effect of using of warm water (20–45 °C) for dough making and washing on separation was studied for BF‐I flour at 640 g kg^?1 water to flour ratio of and 300 s maturation time, and the separation was found to improve with increase in temperature. The combined effects of water temperature (20–50 °C) and water to flour ratio (640–780 g kg^?1 for BF‐I and 620–870 g kg^?1 for BF‐V) were studied at 600 s maturation time. The quantities and dry matter contents of the gluten fraction and starch milk were measured; a sample of starch milk was centrifuged to obtain decantate, tailing and prime starch fractions, and the dry matter contents of each were determined. All the dried samples were also analysed for protein content, and the fractional recoveries of dry matter and protein in the gluten fraction, prime starch, tailings and decantate were calculated. The results indicated the optimum point for BF‐I flour to be the combination of optimum farinograph water absorption and 40 °C. BF‐V showed very poor separation behaviour within the ranges studied. At the optimum farinograph water absorption the use of warm water for dough making and 20 °C water for washing steps was also tried, but no significant improvement over the 20 °C results was obtained. © 2002 Society of Chemical Industry     

Fate of deoxynivalenol,T-2 and HT-2 toxins and their glucoside conjugates from flour to bread: an investigation by high-performance liquid chromatography high-resolution mass spectrometry

Deoxynivalenol, T-2 and HT-2 toxins are mycotoxins frequently occurring in cereals and cereal-based products along with their conjugated forms. In this paper, we provide insights into the fate of deoxynivalenol, T-2 and HT-2 toxins and their glucoside derivatives during bread making, using naturally contaminated wheat flour. High-resolution mass spectrometry was used to assess the extent of degradation of the three mycotoxins during bread baking and to identify some glucoside conjugates, namely deoxynivalenol, T-2 and HT-2 mono-glucosides, detected both in the flour and in the respective breads. Our findings show deoxynivalenol's levels markedly increased upon baking, whereas those of HT-2 and T-2 toxins were decreased in the final bread with special regard to the T-2 toxin.