Correlation Studies of Starch Pasting Properties Determined Through Rapid Visco Analyzer

In present study, pasting properties of wheat varieties were investigated through rapid visco analyzer (RVA). Starch content was determined by Megazyme kit method varied from 68.88 to 72.73%. Pasting properties indicated variability from 65.25 to 67.80 °C (pasting temperature), 3.22 to 6.00 min (peak time), 1330 to 1784 cP (peak viscosity), 645 to 1002 cP (trough viscosity), 1799 to 2565 cP (final viscosity) 685 to 782 cP (breakdown viscosity) and 1154 to 1563 (setback viscosity). Starch content and seven parameters observed from RVA profiles of various wheat varieties were evaluated for their inter- dependence. Starch content indicated a significantly positive association with trough viscosity (r = 0.926*) and final viscosity (r = 0.917*). Present data show that peak viscosity had significant and positive relationship with setback (r = 0.879*) and trough viscosity (r = 0.976**). Novelty statement. Pasting properties determine end use quality of wheat flour and primarily relates to starch content of wheat flour, which is present in largest proportion. In Pakistan, various wheat cultivars are grown in different climate. As a result, the variations in physico-chemical as well as rheological properties of wheat varieties is anticipated. Significant correlations found out in present study are valuable for the evaluation of effect of pasting properties alone and their interaction.

Meta-Analysis of Qtl Associated With Starch Pasting Viscosity in Rice (Oryza Sativa L.)

Rapid Visco Analyzer (RVA) profiles are important traits for indicating rice quality, which are controlled by quantitative trait loci (QTL). In the past two decades, hundreds of QTL for rice RVA profiles have been detected, but without an integration study. Consistent QTL regions associated with rice RVA profiles by QTL meta-analysis with genetic information of 592 QTL for eight RVA profiles were studied. A total of 82 meta-QTL for RVA profiles were detected on 12 chromosomes. MQTL possessed narrower confidence intervals than the initial QTL and candidate genes were identified within each MQTL. These MQTL and candidate genes are beneficial for future marker-assisted selection gene cloning. Bangladesh J. Bot. 50(2): 269-276, 2021 (June)

Pasting Properties of Composite of Cassava and Wheat Flours

Classification of cassava and wheat using only amylose content is not sufficient enough to predict starch viscosity for end product recommendation, hence this study aimed at characterizing and categorizing the pasting profile of composite flours from cassava-citrus and wheat-watermelon using Rapid Visco Analyzer (RVA) (used in confectionary products), dried cassava, citrus rind, wheat grain and watermelon rind were processed into flour by grinding. Cassava-citrus and wheat-watermelon flours were blended in the ratio of 100:0, 25:75, 50:50 and 75:25 and labeled as AB1, AB2, AB3, AB4 and BC1, BC2, BC3, BC4 respectively. The data obtained from the pasting properties of composite cassava-citrus and wheat-watermelon flours are as follows: range of peak viscosity (249.6-446.0) and (97.1-116.3) RVU, trough value (158.5-251.5) and (59.5- 70.3) RVU, breakdown viscosity (91.1-184.1) and (37.6-46.0) RVU, final viscosity (222.3-509.3) and (184.4-214.2) RVU, setback viscosity (63.3-247.8) and (124.9-143.8) RVU, peak time (4.27-5.27) and (5.53- 5.67) min and pasting temperatures (72.45-73.40) and (90.40-91.25) oC. The pasting properties of wheat watermelon composite flours increased with increasing substitution of watermelon fibre while those of cassava citrus composite flours decreased with increasing substitution of citrus fibre until 50% replacement. Composite Cassava-citrus flour AB3 and wheat-watermelon flour BC1 respectively had the highest value for all the pasting properties evaluated. Hence, cassava-citrus flour AB3 with 50% citrus substitution and wheat-watermelon flour BC1 without any substitution could find applications in confectionery and pastry industries. Thus, the results also indicated that by incorporating citrus and watermelon fibre, it is possible to enhance the pasting properties of our local cassava and wheat flour. This will also serve as a way of converting wastes from citrus (citrus vesicles) and Watermelon rinds (Citrullus larnatus) into useful materials, thereby reducing environmental pollutions caused by these wastes.

Technological potential of under-utilized starches from eight varieties of legumes grown in Cameroon

Starch samples from eight legumes cultivars instar of one variety of Vigna unguiculata L. (Cowpea), one variety of Vigna subterrenea V. (Bambara groundnut) and six varieties of Phaseolus vulgaris L. (Common bean), grown in Cameroon were isolated, and their physicochemical and pasting properties were evaluated. The objectives of the study were to investigate the starch properties and processing characteristics of different bean varieties, and to establish the basic foundation of improving the functionality of beans and their starch grown in the region. The result revealed significant differences amongst the properties of the starches. The swelling power of the legume starch isolates put them in the category of highly restricted-swelling starch. This characteristic is desirable for the manufacture of value-added products such as noodles and composite blends with cereals. The pasting properties were determined using a rapid visco analyzer, and various legumes bean starches exhibited different pasting profiles. The high breakdown viscosity (BV) was founded for Cowpea and Bambara groundnut and confirmed their low. ability to resist heat and shear stress when compared to Common bean varieties studies. The factors which influence the pasting characteristics resulting to decrease in peak viscosity (PV), trough viscosity (TV) and final viscosity (FV) of starch are attributed to the interaction of starch with the protein, fat, etc. which depended to their variety.

Pasting properties of raw and extruded cowpea cotyledons flours

There is little research on the viscosity profile analysis of cowpea cotyledon flour (CCF). Due to the new ways of using pulses grains in the diet, it is important to evaluate the viscoamylographic behavior of raw and processed CCF. The CCF was obtained from the cultivars BRS Guariba and BRS Novaera and evaluated in the Rapid Visco Analyzer (RVA). For raw CCF it was used the “Standard 1” program. The extruded CCF was obtained from the cultivar BRS Guariba, which was processed following a central rotational composite design, combining thermoplastic extrusion temperatures (124; 130; 145; 160; 166 °C) and conditioning moisture (16.2%; 17%; 19%; 21%, 21.8%). The obtained extrusions were ground (Ø > 0.5 mm) and evaluated in the RVA using the program “Extrusion 2”. The raw CCF from BRS Guariba presented higher protein, lipid and mineral content and lower carbohydrate content than BRS Novaera. The raw CCF from BRS Guariba showed lower values of pasting temperature (79.35 °C), viscosity breakdown (103.00 cP) and seatback (1447.33 cP) compared to raw CCF from BRS Novaera. The extrusion process drastically changed all viscosity parameters, increasing the initial viscosity value and decreasing the value of other parameters. The extruded CCF had different pasting properties. CCF extruded at 166 °C and 19% moisture resulted in flours with higher initial viscosity and lower retrogradation values, which can be used as a thickener in food products, in addition to increase nutritional value.

Effect of blending and pregelatinizing order on properties of pregelatinized starch from rice and cassava

The aim of this work was to investigate the effects of processing order by mixing and pregelatinizing on properties of pregelatinized starch blends of cassava (C) and rice (R) starches, either mixed in various ratios (0, 10, 30, 50, 70, 90 and 100%C) before pregelatinizing (MP) or with that order exchanged (PM, for pregelatinizing the components before mixing). Starch solids of 45% in water were pregelatinized using double drum drying at 120oC. The water absorption index (WAI) and water solubility index (WSI) were measured, and pasting properties were characterized using Rapid Visco Analyzer (RVA). The results showed that MP (30 - 70%C blends) had WSI half of that of PM, while with 10%C the former gave the higher WSI. In RVA viscosities, especially the hot peak viscosity, MP cases had significantly higher values (p<0.05) than PM for all mixing ratios, indicating interactions in MP and less degradation of starch molecules. The choice of processing order gives some additional control over pregelatinized starch blend behavior in water, while a larger range of control is available by selection of the blend proportions.