Physicochemical,Thermal, Morphological and Pasting Properties of Starches from some Indian Black Gram (Phaseolus mungo L.) Cultivars

The starches separated from thirteen different black gram cultivars were investigated for physicochemical, thermal, morphological and pasting properties. Amylose content, swelling power, solubility and water binding capacity of starches ranged between 30.2–34.6%, 16.0–22.3 g/g, 14.8–17.3% and 73.5–84.5%, respectively. The diameter of starch granules, measured using a laser‐light scattering particle‐size analyzer, varied from 12.8 to 14.3 μm in all black gram starches. The shape of starch granules varied from oval to elliptical. The transition temperatures (T_o, T_p and T_c) and enthalpy of gelatinization (ΔH_gel) determined using differential scanning calorimetry, ranged between 66.1–71.3, 71.0–76.2, 75.9–80.4°C and 6.7–9.4 J/g, respectively. Pasting properties of starches measured using the Rapid Visco Analyser (RVA) also differed significantly. Pasting temperature, peak viscosity, trough, breakdown, final viscosity and setback were between 75.8–80.3°C, 422–514, 180–311, 134–212, 400–439 and 102–151 Rapid Visco Units (RVU), respectively. Turbidity values of gelatinized starch pastes increased during refrigerated storage. The relationships between different properties were also determined using Pearson correlation coefficients. Amylose content showed a positive correlation with swelling power, turbidity and granule diameter. Swelling power showed a negative correlation with solubility and setback. T_o, T_p and T_c showed positive correlation with turbidity, pasting temperature and were negatively correlated to peak and breakdown viscosity.     

Relationships between various functional,thermal and pasting properties of flours from different Indian black gram (Phaseolus mungo L.) cultivars

Flours from different black gram cultivars were investigated for functional, thermal and pasting properties and related to each other using Pearson correlations and principal component analysis (PCA). Ash, fat, protein content and bulk density of flours ranged between 25.7 and 32.5, 5.2 and 10.2, 220 and 289 g kg^?1 and 519 and 563 kg m^?3, respectively. The water absorption capacity (WAC) and oil absorption capacity (OAC) of flours ranged between 2390 and 3450, and 1130 and 1700 g kg^?1, respectively. Least gelation concentration (LGC) for various black gram flours ranged between 8 and 12%, thereby suggesting their good gelating ability. The results showed that the foams produced by black gram flours were relatively thick with low foaming capacity (36.2–49.2%) and foam stability > 90% after 120 min of storage. The transition temperatures (T_o, T_p and T_c) and enthalpy of gelatinization (ΔH_gel) determined using differential scanning calorimeter, ranged between 71.0 and 75.7, 76.1 and 80.4, 81.9 and 86.0 °C, and 3.08 and 3.67 J g^?1, respectively. Pasting temperature, peak‐, breakdown‐, final‐ and setback viscosity were between 68.9 and 81.1 °C, 2988 and 3699, 1200 and 1730, 2839 and 3520, and 1110 and 1474 mPa s, respectively. PCA showed that UG‐218 and UG‐1008 flours were located at the far left of the score plot with a large negative score, while the KU‐3 and UG‐1017 flours had a large positive score in the first principal component (PC1). Overall, these flours differed to the greatest degree in terms of the properties of their flours. Several significant correlations between functional, thermal and pasting properties were revealed both by Pearson correlation and PCA. Copyright © 2007 Society of Chemical Industry     

Physicochemical and functional properties of flours from three Black gram (Phaseolus mungo L.) cultivars

Flours processed from three black gram cultivars (Mash1‐1, PU‐19 and T‐9) were studied for proximate composition, physicochemical and functional properties. Protein, fat, ash and crude fibre content varied significantly (P ≤ 0.05) from 24.5 – 28.4%, 1.1–1.4%, 2.7–3.3% and 2.7–3.4%, respectively, among the cultivars. Significant differences were also observed in other physicochemical properties. Pasting properties like peak viscosity, breakdown viscosity and setback viscosity were in the range of 2078.7–2473.0 cP, 644.0–863.7 cP and 588.3–804.0 cP, respectively. Textural profile analysis of flour gels displayed significant differences in hardness (13.0–18.9 g), gumminess (2.8–5.9 g), chewiness (2.0–5.7 g) and adhesiveness (21.0–40.9 g). Differential scanning calorimetry revealed starch gelatinisation from 63.5 to 75.6 °C and amylose lipid complex melting from 105.0 to 136.1 °C. Protein solubility profile in the pH range of 2–9 varied from 6.3 to 97.3%. Emulsifying activity index and Emulsifying stability index at pH 3, 5 and 7 varied correspondingly from 6.0 to 14.5 m² g^?1 and 18.8 to 64.9 min. Foaming capacity of 2% flour suspensions at pH 2, 4, 6, 8 and 10 varied significantly from 67.3 to 130% among the cultivars. Foam stability varied at different pH and was observed between 0 and 70.8% among the cultivars.     

The effect of rice flour on pasting and particle size distribution of green gram (Phaseolus radiata, L. Wilczek) dried batter

The effect on the pasting characteristics of green gram flour of the addition of rice flour was studied. The gelatinization temperature decreased from 75 °C for the control to 72 °C for samples containing different levels of rice flours. Average particle size of dried batter mix increased with the addition of varying percentages of rice (10, 15, 20 and 25%) from a control value of 236 μm to a maximum 310 μm. The addition of rice flour to green gram increased the water absorption in line with the amount of rice flour added. When rice flour was added, the protein content of the mixed sample of green gram batter and rice flour was reduced accordingly and the fat absorption in the samples also decreased. The foaming capacity of native ground flour, measured after 0.5 min, was double (130 mL) that of dried green gram batter (60 mL) which had been prepared by soaking, wet grinding and drying.     

The effects of extruded black rice flour on rheological and structural properties of wheat-based dough and bread quality

Addition of raw black rice flour leads to deficient processability on bread making quality. One of the effective methods to modify the functional properties of black rice flour (BRF) composite dough is to extrude black rice flour (EBRF) before incorporation. This study investigated and compared the effect of BRF and EBRF addition level of 10%–50% on the rheology, microstructure of dough and bread quality. The rheological properties of composite dough were recorded by Mixolab, stress relaxation and tensile test. The substitution of EBRF presented higher water absorption but lower development time, protein weakening, starch gelatinization, starch gel stability and starch retrogradation than wheat flour dough. Both the BRF and EBRF dough presented solid-like behaviour, while the EBRF dough showed more viscous, higher resistance and extensibility than BRF dough. The dough microstructure of dough was observed by SEM, and a more compact structure of EBRF dough could be seen than BRF dough. The incorporation of EBRF in bread quality presented higher specific volume, lower bake loss and firmness than BRF bread. These findings indicated the potential utilisation value of extruded black rice flour in bread making.     

Phytic acid content of chickpea (Cicer arietinum) and black gram (Vigna mungo): varietal differences and effect of domestic processing and cooking methods

Phytic acid content of various cultivars showed a narrow variation: 7.48-8.00 g kg^?1 and 6.47-6.68 g kg^?1 for chickpea (Cicer arietinum L) and black gram (Vigna mungo L), respectively. Phytic acid was lowered significantly by the common methods of domestic processing and cooking including soaking, cooking, autoclaving and sprouting of the legume grains. Sprouting had the most marked phytic acid lowering effect followed by autoclaving and soaking. Cooking of soaked seeds lowered phytic acid by 20-26% in chickpea and 35-40% in black gram grains whereas the loss was 7-11% and 6-9% in these pulses, respectively, when unsoaked seeds were cooked.     

Effect of extrusion conditions on the physicochemical properties of a snack made from purple rice (Hom Nil) and soybean flour blend

Soy flour was added at levels of 5%, 10%, and 15% of Hom Nil rice flour for extrusion at 190 °C barrel temperature and 350 rpm screw speed. The extruded snack qualities decreased inversely with soy flour. However, product qualities were considered to be optimised when soy flour at 5% was added. The effect of feed moisture content (15, 17, 19 g (100 g)^?1 wb), barrel temperature (150, 170, 190 °C) and screw speed (350, 400, 450 rpm) on physicochemical properties of the snack were then investigated. The physicochemical properties of the product including expansion ratio, density, water absorption index (WAI), water solubility index (WSI) and hardness were evaluated. All properties were related, as linear equations, in terms of feed moisture content, barrel temperature, screw speed with relative correlation (R²) at 0.83–0.94. The snack properties along with consumer acceptance were all highest when the extruded condition were 15 g (100 g)^?1 wb feed moisture content, 170 °C of barrel temperature and 450 rpm of screw speed.