Abid Hasnain

Morphological, Physicochemical, and Pasting Properties of Modified White Sorghum (Sorghum bicolor) Starch

Starch isolated from white sorghum (nWSS) was subjected to chemical modifications to prepare acid thinned (aWSS), oxidized (oWSS), and dual modified acetylated-oxidized (aoWSS) white sorghum starch. Chemical modifications resulted in roughness on the surface of sorghum starch granules. Solubility and paste clarity improved significantly due to the three modifications. Pasting temperature, peak viscosity, and time to reach peak viscosity of modified starches was significantly less than nWSS. Reassociative tendency was curtailed in modified starches as is evident by the decline in setback viscosity. At 8% starch concentration, oWSS and aoWSS completely failed to form a proper gel network.

Functional and Morphological Characterization of Low-Substituted Acetylated White Sorghum (Sorghum bicolor) Starch

Starch isolated from white sorghum (Sorghum bicolor) was acetylated by addition of acetic anhydride at concentrations of 3%, 6%, and 9% w/w of starch under alkaline conditions to produce starch acetates of three different degrees of substitutions. Morphological characterization through scanning electron microscopy revealed roughness on the surface of acetylated starch granules. The modified biopolymer exhibited improved swelling power, solubility, water binding capacity, and paste clarity compared to its native counterparts. Decrease in percent syneresis and gel hardness and extent of reduction in percent transmittance indicate reduced retrogradation tendency of white sorghum starch acetates.

Mango kernel starch-gum composite films: Physical, mechanical and barrier properties

Composite films were developed by the casting method using mango kernel starch (MKS) and guar and xanthan gums. The concentration of both gums ranged from 0% to 30% (w/w of starch; db). Mechanical properties, oxygen permeability (OP), water vapor permeability (WVP), solubility in water and color parameters of composite films were evaluated. The crystallinity and homogeneity between the starch and gums were also evaluated by X-ray diffraction (XRD) and scanning electron microscopy (SEM). The scanning electron micrographs showed homogeneous matrix, with no signs of phase separation between the components. XRD analysis demonstrated diminished crystalline peak. Regardless of gum type the tensile strength (TS) of composite films increased with increasing gum concentration while reverse trend was noted for elongation at break (EAB) which found to be decreased with increasing gum concentration. The addition of both guar and xanthan gums increased solubility and WVP of the composite films. However, the OP was found to be lower than that of the control with both gums. Furthermore, addition of both gums led to changes in transparency and opacity of MKS films. Films containing 10% (w/w) xanthan gum showed lower values for solubility, WVP and OP, while film containing 20% guar gum showed good mechanical properties.

Effect of guar and xanthan gums on functional properties of mango (Mangifera indica) kernel starch

The effects of different concentrations of guar and xanthan gums on functional properties of mango kernel starch (MKS) were studied. Both guar and xanthan gum enhanced the water absorption of MKS. The addition of xanthan gum appeared to reduce the SP (swelling power) and solubility at higher temperatures while guar gum significantly enhanced the SP as well as solubility of MKS. The addition of both gums produced a reinforcing effect on peak viscosity of MKS as compared to control. Pasting temperature of MKS was higher than that of starch modified by gums indicating ease of gelatinization. Guar gum played an accelerative effect on setback but xanthan gum delayed the setback phenomenon during the cooling of the starch paste. Both gums were found to be effective in reducing the syneresis while gel firmness was markedly improved.

Osmotic Dehydration of Mango Cubes: Effect of Novel Gluten-Based Coating

Edible coating before osmotic dehydration (OD) reduces solute uptake, which can deteriorate product quality. Polysaccharide-based coatings have been reported for this purpose with limited success. Gluten, due to its inherent film formation property, has the potential to be used for this purpose. In this study, mango cubes of different maturity were osmotically dehydrated with and without gluten-based coating. An edible coating was prepared through fractionation of gluten. Osmotic dehydration was performed at 50°C for 2 h with osmotic solutions (OSs) at various concentrations (45, 55, 65 °Brix). Coating improved the dehydration efficiency index (DEI) due to a substantial decrease in solute gain (SG) and slight increase in water loss (WL). The coating modified the physicochemical properties and this effect was significantly observed at 55 °Brix. Coated mango cubes were harder and shrank more than uncoated mango. The physicochemical properties after OD were also found to be influenced by the maturity of raw mangoes.

Effect of succinylation on functional and morphological properties of starches from broken kernels of Pakistani Basmati and Irri rice cultivars.

Starch extracted from broken kernels of Basmati and Irri rice varieties of Pakistani rice were subjected to modification by addition of succinic anhydride at levels of 2%, 4% and 5% based on dried weight of starch. The succinyl content of Irri rice starch increased with the concentration of succinic anhydride. Scanning electron micrographs revealed presence of dents and fusion of rice starch granules. Swelling power and water retention capacity (WRC) significantly improved after succinylation while on refrigerated storage percent decline in paste clarity of modified rice starches was stable as compared to native Basmati (BC) and Irri (IC) rice starches. Succinylation also reduced solubility, pasting temperature (PT) and gel hardness of starch gels. Improvement was observed in cold storage stability of rice starch succinates as evident from textural profile analysis.

Effect of pentosans addition on pasting properties of flours of eight hard white spring wheat cultivars.

The effects of water extractable pentosans (WEP) and water unextractable pentosans (WUP) on pasting properties in flours of eight different hard white spring wheat (HWSW) cultivars was studied. WEP and WUP isolated from a hard wheat flour were added to each of the cultivars at 1% and 2% level. The results indicated that WEP exhibited a pronounced effect on pasting properties as compared to WUP and variety. Univariate analysis of variance (ANOVA) was used to evaluate sources of variation. The variety significantly (P < 0.001) influenced all the pasting parameters. WUP caused significant (P < 0.001) variation in paste viscosities (except breakdown). WEP influenced more pronouncedly the hot paste, cold paste, breakdown and setback viscosities with F values—221.802, 214.286, 98.073 and 120.159, respectively. Variety-by-WEP interaction exhibited significant (P < 0.01) influence on pasting time, peak, hot paste and cold paste viscosities. Whereas, variety-by-WUP interaction only significantly (P < 0.001) influenced the pasting- time and -temperature. Duncan’s test was used to analyze the significant difference (P < 0.05) within the variety. The results revealed that WUP did not induce significant (P < 0.05) influence on all the pasting parameters, whereas, WEP influenced significantly (P < 0.05) the paste viscosities of some of the varieties. It was also found that the addition of WEP remarkably reduced the setback, hot paste, cold paste viscosities and increased the breakdown viscosity in all cultivar flours. The effect of WEP was greater at higher level of supplementation on paste viscosities.

Mango kernel starch as a novel edible coating for enhancing shelf- life of tomato (Solanum lycopersicum) fruit

Mango kernel starch (MKS) coatings containing different plasticizers were used to extend the shelf life of tomato. The coating slurry was prepared by gelatinizing 4% mango kernel starch, plasticized with glycerol, sorbitol and their 1:1 mixture (50% of starch weight; db). The samples were kept at room temperature (20°C) and analyzed for shelf life. Significant difference in coated and control fruits were observed and all the coated fruits delayed ripening process that was characterized by reduction in weight loss and restricted changes in soluble solids concentration, titratable acidity, ascorbic acid content, firmness and decay percentage compared to uncoated sample. The formulations containing sorbitol were found to be the most effective followed by combined plasticizers (glycerol: sorbitol) and glycerol. Sensory evaluation conducted to monitor the change in color, texture and aroma also proved the efficacy of MKS coating containing sorbitol by retaining the overall postharvest quality of tomato during the storage period. The results showed that MKS could be a promising coating material for tomatoes that delayed the ripening process up to 20days during storage at 20°C with no adverse effect on postharvest quality.

Influence of xanthan, guar, CMC and gum acacia on functional properties of water chestnut (Trapa bispinosa) starch

This study was performed to determine the effect of xanthan, guar, CMC and gum acacia on functional and pasting properties of starch isolated from water chestnut (Trapa bispinosa). Morphological properties of water chestnut starch with CMC were studied by scanning electron microscopy (SEM). The addition of hydrocolloids significantly enhanced the solubility of water chestnut starch (WCS) while reduced swelling power and freeze-thaw stability. The hydrophilic tendency of WCS was increased by xanthan gum; however, with addition of gum acacia it decreased significantly. Starch was modified with guar and gum acacia exhibited highest% syneresis. Guar gum was found to be effective in increasing the clarity of water chestnut starch paste. The addition of CMC significantly reduced the pasting temperature of WCS indicating ease of gelatinization. The setback was accelerated in the presence of xanthan gum but gum acacia delayed this effect during the cooling of the starch paste. Only xanthan gum was found to be effective in increasing breakdown showing good paste stability of WCS.

Thermal Characterization of Native and Modified White Sorghum (Sorghum Bicolor) Starch

Gelatinization and retrogradation characteristics of native and modified white sorghum (Sorghum bicolor) starches were studied using differential scanning calorimetry. The biopolymer was modified through acetylation, oxidation, and acid thinning reactions to prepare single- and dual-modified white sorghum starches. The results revealed that peak gelatinization temperature (Tp) of AWSS (acetylated white sorghum starch) and AOWSS (acetylated-oxidized white sorghum starch) was less than that of NWSS (native white sorghum starch), while oxidation and acid thinning significantly increased the peak gelatinization temperature. Gelatinization enthalpy (ΔH) of ATWSS (acid-thinned white sorghum starch) was the least among both native and modified starches, which indicates weakening of starch granules after acid modification. Rate of retrogradation was lower in AWSS, OWSS, and AOWSS than NWSS, whereas acid thinning increased the rate of retrogradation. After 12 days of refrigerated storage at 4°C, percent retrogradation was in the order ATWSS > NWSS > AWSS∼AOWSS > OWSS. However, percent increment in retrogradation enthalpy was the least in AWSS.