Physicochemical,Pasting, Thermal and Morphological Characteristics of Indian Water Chestnut (Trapa natans) Starch

Starch extracted from Indian water chestnut was investigated for its physicochemical characteristics. The results were compared with those obtained from two commercial starches (corn and potato). The pasting properties were tested in the Rapid Visco Analyser and thermal properties with a differential scanning calorimeter. Water chestnut starch possessed higher breakdown viscosity (BV) and setback viscosity (SV) than corn and potato starches. However, the pasting temperature of water chestnut starch was not significantly different from that of corn starch. Lower ΔH_gel values were obtained for water chestnut starch than for the other two starches whereas the onset, peak and conclusion temperatures of gelatinization (T_o, T_p and T_c) for water chestnut starch were quite comparable with corn starch. Scanning electron micrographs showed similarity in starch granule shape between water chestnut and potato starch with corn starch showing surface wrinkles on starch granule surfaces.     

Pasting Properties of Potato Starch and Waxy Maize Starch Mixtures

The pasting viscosity, morphological properties, and swelling properties of potato starch and waxy maize starch mixtures at different ratios were investigated. Pasting analysis of the starch mixtures (7% solids in water, w/w) using a Rapid Visco Analyser showed linear changes in peak viscosity and pasting temperature according to the mixing ratios of both starches, but not in breakdown and setback. The pasting profile revealed that the starches rendered mutual effects during pasting, more significantly when the amounts of potato and waxy maize starches were similar. The volume fraction of swollen granules and the presence of amylose appeared to be important parameters in the mutual effects of both starched during pasting. Under a light microscope, the swelling of potato starch granules was delayed by the presence of waxy maize starch. Overall results indicate that new pasting properties can be generated by mixing starches of different botanical sources.     

Relationships Between Selected Properties of Starches from Different Corn Lines

Starch was isolated from the corn lines obtained by crossing two different germ pools (MS and Tux pool) and evaluated for amylose content, swelling power, solubility, water binding capacity (WBC) and syneresis. The gelatinization (T_o, T_p, T_c, ΔH_gel, PHI & R) and pasting (pasting temperature, peak viscosity, breakdown viscosity, final viscosity and set back) properties of starches were measured using Differential Scanning Calorimeter (DSC) and Rapid Visco Analyzer (RVA), respectively. The relationships between different properties were also determined using pearson correlation coefficients. Amylose content was negatively correlated to swelling power and WBC (p < 0.05). Several significant relationships were also observed between thermal and pasting properties of isolated starches. Transition temperatures (T_o, T_p & T_c) and PHI showed positive correlation with peak, trough and breakdown viscosity (p < 0.05). Syneresis of starches was positively correlated to amylose content (p < 0.05).     

Relationships Between Some Physicochemical Properties of Starches from Maize Cultivars Grown in East China

Granule size, amylose content, degree of crystallinity, thermal, pasting, and gel textural properties of starches separated from thirty seven maize cultivars grown in East China were studied with a laser particle size analyzer, spectrophotometer, X‐ray diffractometer, differential scanning calorimeter, Rapid Visco Analyser, and texture analyzer. Various correlations between the physicochemical properties were observed. The correlation coefficient between T_o and T_p, between T_o and T_c, and between T_p and T_c were 0.967, 0.879, and 0.941 (p<0.01), respectively. Amylose content was correlated negatively with T_c (r=‐0.640, p<0.01). Pasting temperature was positively correlated to T_p (r=0.738, p<0.01). Significantly positive correlations were observed between amylose content and final viscosity, between amylose content and setback (r=0.665 and 0.735, respectively, p<0.01) and between peak viscosity and breakdown (r=0.893, p<0.01). Trough viscosity was positively correlated to final viscosity and setback (r=0.851 and 0.704, respectively, p<0.01). Significant correlations existed between final viscosity and setback, and hardness (r=0.972 and 0.615, respectively, p<0.01). There was a significant interrelationship between setback and hardness (r=0.655, p<0.01).     

Physicochemical properties of acetylated starches from some Indian kidney bean (Phaseolus vulgaris L.) cultivars

Starches separated from four kidney bean cultivars were modified by acetylation to reduce retrogradation and increase gel stability and compared with respective native starches (data of native starch reported by Wani et al., 2010 ). Acetylation was carried out by treating starches with 0.04 and 0.08 g of acetic anhydride per gram of starch dry weight basis (dwb) at 25 °C and pH between 8.0 and 8.5. The extent of acetylation increased proportionally with the concentration of acetic anhydride used. The pasting curves of 10.7% starch determined by Rapid Visco Analyzer at 160 rpm showed that acetylation decreased the setback viscosity values by 0.64–34.58% and pasting temperature by 4.4–9.2 °C when compared with the native starch. Differential scanning calorimetry observations also revealed significant (P ≤ 0.05) decrease in gelatinisation temperature of acetylated starches than the corresponding native starches. Hardness of starch gels varied between 14.3 and 44.0 g, which was significantly (P ≤ 0.05) lower than the corresponding native starch gels.     

Effect of ionic gums and dry heating on physicochemical,morphological, thermal and pasting properties of water chestnut starch

Starch from water chestnuts (Trapa natans) was isolated and modified by dry heating and hydrocolloids [carboxy methyl cellulose (CMC) and sodium alginate]. Native and modified starches were evaluated for their physicochemical, pasting, thermal and morphological properties. Pasting and thermal properties were studied using Rapid Visco Analyzer (RVA) and Differential Scanning Calorimeter (DSC) respectively. Morphological properties were studied by Scanning Electron Microscopy (SEM). Modification of the starch by dry heating with and without gums reduced paste clarity and increased the water and oil binding capacity; solubility and swelling power decreased. Dry heating of native starch increased peak viscosity; however, with addition of CMC, peak viscosity decreased. Starch modified with CMC and 4 h heating exhibited lowest gelatinization temperature (T₀). Pasting characteristics of native water chestnut starch were largely affected by the addition of gums and/or heat treatment. Overall onset gelatinization temperature reduced with heat treatment and addition of gums. Morphological studies revealed no significant variation in starch granule size. Starch granules were seen agglomerated because of leaching of amylose and granule interspacing decreased with addition of gums.     

Physicochemical and structural characteristics of starches from Chinese hull‐less barley cultivars

Fourteen hull‐less barley cultivars, collected from four major cultivated areas in China, were employed to investigate the structural and physicochemical properties of their starches in this study. Relatively wide variations in physicochemical properties of the starches were observed. Amylose content ranged from 23.1% to 30.0%, swelling power and water solubility index ranged from 12.8 to 19.9 g g^?1 and 12.7% to 23.7% respectively. Peak viscosity was from 170 to 346 Rapid Visco Unit (RVU), peak temperature (T_p) of starch gelatinisation was from 55.6 to 61.8 °C and enthalpy of starch retrogradation ranged from 0.3 to 3.1 J g^?1. Weight‐based chain‐length proportions of fa, fb₁, fb₂ and fb₃ in amylopectins ranged from 21.65% to 24.95%, 44.48% to 49.44%, 15.56% to 17.19% and 9.83% to 16.66% respectively. Correlation analyses showed that amylose content was inversely related to pasting parameters and enthalpy of gelatinisation. Pasting properties and amylopectin structures were the most important parameters to differentiate starch properties among different hull‐less barley cultivars in this study. This work will be useful for exploring applications of Chinese hull‐less barley starches in food and non‐food industries.     

Physicochemical Properties of Caribbean Sweet Potato (Ipomoea batatas (L) Lam) Starches

The proximate compositions and physicochemical properties of 21 Caribbean sweet potato (Ipomoea batatas (L) Lam) starches were investigated. Proximate composition, amylose, reducing and non-reducing sugars were determined using standard methods. Swelling power and solubility were evaluated and pasting properties of the starches were determined using Rapid Visco Analyzer. Moisture (8.0–12.4%), protein (0.0–0.2%), ash (0.1–0.5%), and reducing (0.3–2.3%) and non-reducing sugar (0.1–0.2%) contents of starches were significantly different (P < 0.05) among the cultivars. Amylose content varied significantly between 12.8–21.3%. Swelling power and solubility ranged between 7.8–31.1% and 1.5–9.6%, respectively. Pasting properties such as peak viscosity measured in Rapid Visco Units (143.2–288.8 RVU), breakdown viscosity (29.4–162.6 RVU), and setback viscosity (15.0–78.8 RVU), pasting temperature (73.5–87.7 °C) and time to pasting temperature (3.6–4.5 min) varied significantly among the cultivars. Breakdown viscosity was poorly correlated with final viscosity attained (r = − 0.0507, P < 0.05); however, pasting temperature was correlated (r = 0.479, P < 0.05) with setback viscosity. The variability observed in the physicochemical properties of the starches was related to specific requirements for use in the production of noodles, pasta, and inclusion in bread and weaning food formulations.     

Proximate Composition of Triangular Pea,White Pea,Spotted Colored Pea,and Small White Kidney Bean and Their Starch Properties

Physicochemical properties of beans and starches extracted from triangular pea, white pea, spotted colored pea, and small white kidney bean grown in China were investigated. Results pointed out that each of the different legumes might be a good resource of starch and protein, which could be utilized for specific applications in food processing. Starches separated from different legumes differed significantly with respect to their protein content, amylose/amylopectin ratio, lipid content, ash content, swelling power, and solubility. The scanning electron micrographs revealed the presence of kidney or elliptical- to irregular-shaped granules and with a diameter ranging from 5 to 40 μm. All starches exhibited a C-type X-ray diffraction pattern. The pasting properties were tested in a Rapid Visco Analyser and thermal properties with a differential scanning calorimeter. Small white kidney bean had the highest peak, trough, breakdown, and final viscosity among various starches. Triangular pea starch showed the highest gelatinization transition temperatures (T _o, T _p, and T _c) and enthalpy of gelatinization, while white pea starch showed the lowest transition temperatures and gelatinization enthalpy. The results obtained provide a technical basis for processing these legumes and starches.     

Effect of Amylose Content on Gelatinization,Retrogradation and Pasting Properties of Flours from Different Cultivars of Thai Rice

Presently, rice cultivars are categorized according to amylose content into three groups: low, medium and high amylose content cultivars. The correlation of amylose content with gelatinization properties, retrogradation, and pasting properties of eleven cultivars of Thai rice were investigated. Rice flour was prepared from milled rice by the wet grinding process. Onset (T_o), peak (T_p) and conclusion (T_c) temperatures of gelatinization, (determined by DSC) were found to be highly positively correlated with amylose levels. This correlation could be used for prediction of amylose content of rice flour. Low amylose starch could also be characterized by low degree of retrogradation (%R). The data obtained from RVA‐viscograms (peak viscosity, breakdown, setback, and pasting temperature) can be used only for characterization of the group of low amylose starches (waxy rice). It was demonstrated that low amylose rice starch provided the highest peak viscosity and breakdown and the lowest setback and pasting temperature among the groups investigated.     

Physico‐chemical properties of starches from Indian kidney bean (Phaseolus vulgaris) cultivars

Starches isolated from four Kidney bean cultivars (French Yellow, Contender, Master Bean, Local Red) grown in temperate climate were studied for their physico‐chemical, morphological, thermal, pasting, textural and retrogradation properties. Physico‐chemical properties such as composition, amylose content, water absorption capacity, swelling power, syneresis, freeze–thaw stability and light transmittance showed significant differences among starches. Amylose content (36.4–41.7%) showed strong correlations with peak, trough, breakdown, final and setback viscosity, gel hardness, gumminess and chewiness. The starch granule morphology of these starches showed considerable variation when studied by scanning electron microscopy. Starch granules were observed to be round, irregular or elliptical with smooth surfaces. Master Bean starch granules were larger than those of other kidney bean starches. Pasting and textural properties of French Yellow starches were found to be higher than other kidney bean starches. Local Red starches showed the highest gelatinisation transition temperatures, whereas Master Bean starches showed the lowest transition temperatures.     

Thermal and Pasting Properties of Microwaved Corn Starch

Corn starch with 15–40% moisture was irradiated at 0.17 or 0.5 W/g for 1 h using the sophisticated Ethos 1600 microwave apparatus that accurately controls temperature and wattage. Temperature of irradiated starch was measured during microwaving. Thermal and pasting properties were studied on dehydrated starch after microwave irradiation. Temperature increases were greatest during the first 10 min for starch at all moisture contents at both microwave power levels. Starch irradiated at 0.17 W/g had a temperature below onset gelatinization temperature (T_o) after 1 h. Higher temperatures were observed for starch with higher moisture content and microwaved at 0.5 W/g. Compared to native starch, starch with 15–40% moisture had higher T_o (measured using differential scanning calorimetry) and with 35–40% moisture had higher peak gelatinization temperature and lower enthalpy change of gelatinization. All paste viscosity parameters measured by the Rapid Visco Analyser were reduced and pasting temperature was elevated for starch irradiated at 0.5 W/g compared to native starch.     

Development and Testing of Methods to Screen Chickpea Flour for Starch Characteristics

Rapid screening methodology has been developed for assessing the chemical composition and the gelatinisation and pasting properties of starch using flour from chickpea seeds. The methodology allows samples to be assessed using a minimal amount of sample and for starch information to be interpreted in the presence of other components present in the flour. The starch content of the flour and the amylose content of the starch was determined by modifying existing kit-based methods (Megazyme International Ltd). Using the Differential Scanning Calorimeter (DSC), starch gelatinisation characteristics can be assessed based on temperature of gelatinisation (T_p), specific heat capacity (Cp^sp ) and half width of transition (½ΔT). Pasting properties could be assessed using the Rapid Visco Analyser (RVA), based on the determination of onset temperature for the RVA profile (T \displaystyle _o^{RVA} ), T_p − T \displaystyle _o^{RVA} and final viscosity (FV) values. The developed methodology was tested using a range of chickpea samples. No significant variation was found between the samples for starch content or for the proportion of amylose/amylopectin in the various starches. Significant variation was found in the starch properties of two of the samples, while the variation between the remaining samples was very small.     

Influence of Heat‐Moisture Treatment and Acid Modifications on Physicochemical,Rheological, Thermal and Morphological Characteristics of Indian Water Chestnut (Trapa natans) Starch and its Application in Biodegradable Films

Water chestnut starch was subjected to acid modification and heat‐moisture treatment. Hydrochloric acid was used for acid modification at three different concentrations (0.25 M, 0.5 M and 1 M) for 2 h. Modifications did not alter the granule morphology. Heat‐moisture treatment (HMT) resulted in slight reduction in the granular size of the starch granules. Acid modification lowered the amylose content, swelling power, water‐ and oil‐binding capacity but improved the solubility of starch to a considerable level. Light transmittance of acid‐modified (AM) starches improved significantly. A significant reduction in peak, trough, final and setback viscosity was observed by acid‐thinning. In case of heat‐moisture treated starch the final viscosity (F_v) was found to be even higher than the peak viscosity (P_v). Native water chestnut starch exhibited a lower onset temperature (T_o) and peak temperature (T_p) of gelatinization than the corresponding acid‐treated starches. Starch films prepared from native starch exhibited excellent pliability, whereas those prepared from AM and HMT starches showed good tensile strength. Starch films prepared from acid‐treated starches provided better puncture and tensile strength.     

Relationships Between Selected Properties of Seeds,Flours, and Starches from Different Chickpea Cultivars

ABSTRACT

Five desi (PBG-1, PDG-4, PDG-3, GL-769, and GPF-2) and one kabuli type (L-550) chickpea cultivars were evaluated for their seed mass, volume, hydration capacity, swelling capacity, cooking time, and instrumental textural properties (hardness, cohesiveness, gumminess, and chewiness). Flour was prepared from these chickpea cultivars and various physicochemical and functional properties were determined. The pasting (pasting temperature, peak viscosity, breakdown, and final viscosity) and gelatinization (T _o, T _p, T _c, and ΔH _gel) properties of these flours were measured using Rapid Visco Analyzer (RVA) and Differential Scanning Calorimeter (DSC), respectively. Starch was also isolated from chickpea cultivars and evaluated for amylose content, swelling power, solubility, and syneresis values. Physicochemical, cooking, and instrumental textural properties of seeds of different chickpea cultivars were related to physicochemical, gelatinization, and pasting properties of their flours and physicochemical properties of their starches. Selected properties of chickpea seeds were significantly correlated with the properties of their starches and flours. Hardness value of soaked chickpea seeds was positively correlated to cooking time, seed mass, seed volume, hydration, and swelling capacity (p < 0.01). Water solubility index (WSI) of chickpea flours was positively correlated to seed mass, volume, hydration capacity, and hardness value (p < 0.05). Selected instrumental textural parameters of seeds had positive correlation with ΔH _gel of flours (p < 0.01). Peak viscosity of flours showed positive correlation to breakdown, final viscosity, bulk density, and negative correlation to cohesiveness of soaked seeds (p < 0.01). Final viscosity showed negative correlation to bulk density and water absorption index (WAI) (p < 0.01) of flours.     

Gelatinisation Characteristics of Cassava Starch Settled in the Presence of Different Chemicals

Addition of chemicals during the extraction of cassava starch for enhancing the settling rate, whiteness and compactness of the settled starch is an accepted commercial practice. The effect of addition of selected chemicals such as acids (sulphuric and hydrochloric acids), bleaching and oxidising agents (sodium metabisulphite and sodium hypochlorite) and alum during settling on the thermal and pasting properties of the cassava starch was examined. Treatment with sulphuric acid produced a noticeable increase in all DSC gelatinisation parameters, viz. onset gelatinisation temperature (T_o), temperature at peak minimum (T_p) and end temperature (T_e), with increasing concentration of acid, while only a marginal shift could be obtained even at higher concentration of hydrochloric acid. However, no major effect resulted from treatment with sodium metabisulphite, sodium hypochlorite and alum. The gelatinisation enthalpy was hardly affected by the treatments. An exception was hydrochloric acid, which brought about a perceptible decrease in enthalpy at higher concentrations indicating that starch crystallinity is influenced to a small extent by hydrochloric acid. Pasting characteristics studied using a Rapid Visco Analyser showed that sulphuric acid, even at the lowest concentration (5 mM), considerably affected the structural characteristics of cassava starch, while hydrochloric acid induced similar effect only at higher concentrations. Alum reduced the paste viscosity while the bleaching agents (sodium metabisulphite and sodium hypochlorite) were not so effective in modifying the starch viscosity characteristics.     

Some Physical and Chemical Properties of Starch Isolates of Cassava Genotypes

Cassava starches (Manihot esculenta Crantz) were prepared from tubers of Kaesetsart 50 (KU50), Rayong 5, Hanatee and KMUL 36‐YOO2 (YOO2) and their physicochemical properties studied using the Rapid Visco Analyser (RVA), differential scanning calorimetry (DSC) and rheometry. Amylose content was determined by iodine potentiometric titration (IPT) and gel permeation chromatography (GPC). Starch contents of the tubers varied from 34.2 to 35.1% and protein and fiber contents in the starches varied from 0.8 to 1.1% and 0.6 to 0.8%, respectively. The cassava starches contained 0.06–0.12% lipid and 0.7% to 0.9% ash. Amylose content determined by IPT (15.9 to 22.4%) had higher positive correlation with peak viscosity, breakdown and gel consistencies (R₂ = 0.835, 0.772, 0.859), respectively, whereas GPC (18.1 to 25.3%) showed high correlation with setback (R₂ = 0.923) and ΔH (R₂ = 0.579). The onset gelatinization temperatures varied from 59.7–64.4°C, and KU50 exhibited highest ΔH of 13.7 J/g. Hanatee and YOO2 formed clear gels with higher peak viscosities, setback and gel consistency viscosities attributed to their higher amylose contents. Retrogradation of KU50 and Rayong 5 tended to be more severe on cooling and formed opaque gels, showing higher resistance to shearing, properties attributed to recrystallized amylopectin fractions.     

Use of the Rapid-Visco-Analyzer to Measure Starch Pasting Properties. Part I: Effect of Sugars

The Rapid Visco-Analyzer (RVA) was used to measure the effects of dextrose, sucrose, corn syrup solids and polydextrose on maize, tapioca and wheat starch pasting properties. The addition of 1 part sugar: 1 part starch tended to decrease peak viscosity, whereas peak viscosity increased at higher sugar concentrations (up to 4 parts sugar: 1 part starch). Time to onset of viscosity increase and time to peak viscosity increased as sugar concentrations increased. Dextrose, sucrose and corn syrup solids increased the maximum setback viscosity, of the starches, but polydextrose reduced setback viscosity. As the molecular weights of the sugars increased, the effects generally increased for maize and tapioca starches but not for wheat starch. Pasting property parameters measured in the RVA concurred with data obtained using other viscometers or by other techniques previously reported. The RVA is useful as an alternative tool for studying starch pasting properties and the effects of food ingredients on starch performance.     

Physicochemical,morphological, thermal and rheological properties of starches separated from kernels of some Indian mango cultivars (Mangifera indica L.)

The starches separated from kernels of five different Indian mango cultivars (Chausa, Totapuri, Kuppi, Langra and Dashehari) were investigated for physicochemical, morphological, thermal and rheological properties. Mean granule length and width of the starches separated from mango cultivars ranged between 15.8–21.7 and 8.7–14.1 μm, respectively. The shape of starch granules varied from oval to elliptical. Amylose content of mango kernel starches from different cultivars ranged from 9.1 to 16.3%. Totapuri kernel starch, with the largest mean granular size, had the highest amylose content, while Chausa kernel starch, with the lowest mean granular size had the lowest amylose content. The transition temperatures (T_o, T_p and T_c) and enthalpy of gelatinization (ΔH_gel) were determined using differential scanning calorimetry (DSC). T_o, T_p and T_c varied from 73.4 to 76.3, 78.1 to 80.3 and 83.0 to 85.7 °C, respectively. Chausa kernel starch showed the highest T_o, T_p, T_c, ΔH_gel and peak height index among starches from different mango cultivars. The rheological properties of the starches from different mango cultivars measured using a dynamic rheometer, showed significant variations in the peak G′, G″ and peak tan δ values. Totapuri kernel starch showed the highest peak G′, G″, breakdown in G′ and lowest peak tan δ values. The large-size granules of Totapuri kernel starch appeared to be associated with higher values of peak G′ and G″. The turbidity of the gelatinized aqueous starch suspensions, from all mango cultivars, increased with increase in storage period. Dashehari starch paste showed lower turbidity values than other mango cultivars.     

Properties of starches of some West African yams

The tuber starches of several species and varieties of yam (Dioscorea) grown as food crops in West Africa were examined. The granule sizes were investigated, and the forms of the starch granules are illustrated in photographs. Amylose contents were also measured, together with ‘pasting temperatures’, viscous properties and gel strength. The granules of D. rotundata and D. alata were large (10–70 μ) while those of D. esculenta and D. dumetorum were much smaller (1–5 μ). The starch of D. rotundata gave the most viscous solutions, but that of D. alata gave the strongest gel. Pasting temperatures ranged between 76° and 85°.