Some properties of corn starches II: Physicochemical,gelatinization, retrogradation,pasting and gel textural properties

The physicochemical, thermal, pasting and gel textural properties of corn starches from different corn varieties (African Tall, Ageti, Early Composite, Girja, Navjot, Parbhat, Partap, Pb Sathi and Vijay) were studied. Amylose content and swelling power of corn starches ranged from 16.9% to 21.3% and 13.7 to 20.7 g/g, respectively. The enthalpy of gelatinization (ΔH_gel) and percentage of retrogradation (%R) for various corn starches ranged from 11.2 to 12.7 J/g and 37.6% to 56.5%, respectively. The range for peak viscosity among different varieties was between 804 and 1252 cP. The hardness of starch gels ranged from 21.5 to 32.3 g. African Tall and Early Composite showed higher swelling power, peak, trough, breakdown, final and setback viscosity, and lower ΔH_gel and range of gelatinization. Pearson correlations among various properties of starches were observed. Gelatinization onset temperature (T_o) was negatively correlated to peak-, breakdown-, final- and setback viscosity (r = −0.809, −0.774, −0.721 and −0.686, respectively, p < 0.01) and positively correlated to pasting temperature (r = 0.657, p < 0.01). ΔH_gel was observed to be positively correlated with T_o, peak gelatinization temperature and (T_p) and gelatinization conclusion temperature T_c (r = 0.900, 0.902 and 0.828, respectively, p < 0.01) whereas, it was negatively correlated to peak- and breakdown- (r = −0.743 and −0.733, respectively, p < 0.01), final- and setback viscosity (r = −0.623 and −0.611, respectively, p < 0.05). Amylose was positively correlated to hardness (r = 0.511, p < 0.05) and gumminess (r = 0.792, p < 0.01) of starch gels.     

A comparison of native and oxidized normal and waxy corn starches: Physicochemical, thermal, morphological and pasting properties

The effect of sodium hypochlorite on the physicochemical and functional properties of normal and waxy corn starches was investigated in this study. It was found that both carboxyl and carbonyl contents of oxidized starches from normal corn were higher than those of waxy corn. The introduction of carboxyl and carbonyl groups resulted in lower amylose content and swelling power. Both amylose and amylopectin were oxidized and degraded during oxidation but amylose was more susceptible to oxidation. Studies conducted on paste clarity revealed that the percentage transmittance increased after oxidation. The morphology of the starches was not altered after oxidation. Thermal properties measured by differential scanning calorimeter, showed that oxidation reduced transition temperatures (onset temperature, T_o; peak temperature, T_p; and conclusion temperature, T_c), gelatinization and retrogradation enthalpies of both normal and waxy corn starches. The retrogradation tendency was reduced after oxidation both in normal and waxy corn starches. Oxidation produced waxy starch with significantly higher peak (P_V), trough (T_V), breakdown (B_V), final (F_V), and setback viscosity (S_V) as demonstrated by using a rapid visco analyzer. Oxidation reduced the pasting temperature of both normal and waxy corn starches. Also, the principal component analysis (PCA) study was conducted to find the overall variations among the oxidized starches studied. Together, the first two components represent 88.7 g/100 g of the total variability.     

A comparison of native and acid thinned normal and waxy corn starches: Physicochemical, thermal, morphological and pasting properties

The starches isolated from normal and waxy corn varieties were hydrolyzed with hydrochloric acid (0.14 mol equivalent/L) and evaluated for physicochemical and functional properties. Acid thinning decreased the amylose content and swelling power but increased the solubility. The light transmittance of acid thinned (AT) starch pastes was higher than those of their native starches after similar storage intervals. The scanning electron microscopic observation demonstrated that the acid thinning did not cause any disruption of the granular crystalline structure. Native normal corn starches showed lower onset temperature (T_o) and peak temperature (T_p) as compared to their counterpart AT starches, whereas the reverse was observed for waxy corn starch. Enthalpy of gelatinization (ΔH_gel) was lower in AT normal and waxy starches as compared to their native starches. The percentage of retrogradation (%R) was significantly higher for native corn starches as compared to their AT starches. A significant reduction in peak—(P_V), trough—(T_V), breakdown—(B_V), final—(F_V), and setback viscosity (S_V) was observed by acid thinning, and the reduction was more pronounced in AT waxy starches. Among AT starches, AT waxy starch showed the lowest values of P_V, T_V, B_V, F_V and S_V.     

Physicochemical properties,resistant starch content and enzymatic digestibility of unripe banana,edible canna,taro flours and their rice noodle products

Unripe banana, edible canna and taro flours, which have been reported to contain significant amounts of fibre, were investigated for their physicochemical properties, resistant starch (RS) content and in vitro starch digestibility, and compared with commercial high‐fibre‐modified starches from corn and tapioca. Differential scanning calorimetry showed a single endothermic peak located around 70–83 °C for the samples except the modified starches, which exhibited no transition enthalpy. The samples showed different pasting behaviours in the Rapid Visco‐Analyser (RVA) ranging from full to restricted swelling. The RS content varied from 1–26 g per 100 g dry sample, and the estimated glycaemic indices (GIs) of the samples were from 67% to 99%. Generally, samples with high RS were low in GI values. The starches produced acceptable rice noodles but with reduced rate of starch digestion and GI. The effects of the unripe banana, edible canna and taro flours on starch digestibility were either comparable or better than the commercial modified starches. These flours can substitute commercial modified starches to lower GIs of noodles and identical foods.     

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.     

Protein characteristics and peroxidase activities of different Indian wheat varieties and their relationship to chapati-making quality

Different wheat varieties grown at a single geographical location were evaluated for protein quantity and quality, rheological properties, and activities of peroxidase as well as polyphenol oxidase. The protein content in these varieties ranged from 11.6 to 14.6%, farinograph water absorption ranged from 70 to 76%, and the damaged starch content varied from 12.3 to 16.3%. The total protein content of whole wheat flours significantly correlated to stiffness (R/E values) of the dough (r=0.73, p<0.05); however, it did not influence any of the quality parameters of chapati. However, the protein quality parameter, Glu-1 score, which reflects the high molecular weight (HMW) glutenin subunit composition, correlated significantly to the cutting force, which indicates the texture of chapati (r=0.78, p<0.05). The quantity of low molecular weight protein fraction having molecular weight of 20 kDa showed significant correlation to over all quality scores of chapati (r=0.78, p<0.05). The color of chapatis was significantly correlated to color of dough (r=0.76, p<0.05), which became darker on resting. Peroxidase activity greatly influenced the color of chapatis (r=0.81, p<0.05).     

Effect of calcium content in the corn flour on RVA profiles

Corn flour was produced using the traditional nixtamalization process and different steeping times of 0, 1, 5, 6, 10, 13, and 24 h. The flour particle size distribution was then evaluated in terms of the particles retained by using a 40 US mesh screen. The lime content, the Rapid Visco Analyzer (RVA) profiles, maximum peak viscosity, breakdown and final viscosity (V) were measured as a function of the steeping time. It was found that the initial rate of increase in viscosity (dV/dt), maximum peak viscosity, breakdown and final viscosity of fractions depended on the amount of calcium incorporated in the corn kernels during the steeping time (T_s) of the nixtamalization process. The particles retained using a 40 mesh that were steeped for 0-5 h, do not have the characteristic points of an RVA profile, i.e., maximum peak viscosity and breakdown. However, the particles retained using a 40 mesh and steeped for 6-24 h developed peak viscosity, breakdown and final viscosity. The corn flours that are recommended for making tortillas are precisely the flours whose particle size distributions develop these three characteristic points in the RVA profile. Differences in RVA measurements of the size fractions can be explained on the basis of the calcium content of the course fractions of corn flours. It was concluded that RVA characteristics may be changed by the calcium content in the starch polymer structures created during the nixtamalization process. Consequently, the increased calcium content in starch particles should be reflected in RVA measurements as an increase in the peak viscosity, in the gelatinization rate and in the development of a noticeable breakdown.     

Physicochemical and functional properties of whole legume flour

The physicochemical, functional and pasting properties of whole flours from pinto bean, lima bean, red kidney bean, black bean, navy bean, small red bean, black eye bean, mung bean, lentil and chickpea were investigated. Significant differences in physicochemical characteristics and functional properties were observed (P < 0.05). Bulk densities, water absorption indices, water solubility indices, oil absorption capacities, emulsion activities, and emulsion stabilities ranged from 0.543 g/mL to 0.816 g/mL, 4.09 g/g to 6.13 g/g, 19.44 g/100 g to 29.14 g/100 g, 0.93 g/g to 1.38 g/g, 61.14%–92.20%, and 84.15%–96.90%, respectively. Phaseolus legume flour exhibited higher water absorption capacity, oil absorption capacity, emulsion activity, and emulsion stability compared with other kinds of legume flour. Pasting properties were significantly different (P < 0.05). Pasting temperatures and the peak, final, and setback viscosities of the flours ranged from 73.2 °C to 83.0 °C, 96.2 RVU to 216.8 RVU, 118.5 RVU to 243.8 RVU, and 28.3 RVU to 103.2 RVU, respectively.     

Comparative study of the functional,thermal and pasting properties of flours from different field pea (Pisum sativum L.) and pigeon pea (Cajanus cajan L.) cultivars

Physicochemical, functional, thermal and pasting properties of flours from field pea (LFP-48 and PG-3) and pigeon pea (AL-15 and AL-201) cultivars were determined and related to each other using Pearson correlation and principal component analysis (PCA). Field pea flours (FPF) were significantly (P < 0.05) different from pigeon pea flours (PPF) in their lower ash and higher fat and protein contents. FPF also exhibited higher L^∗, ΔE value, water solubility index (WSI), oil absorption capacity (OAC), foaming capacity (FC) and lower a^∗, b^∗ value, water absorption index (WAI) and water absorption capacity (WAC) in comparison to PPF. FPF differed significantly from PPF in exhibiting lower transition temperatures (T_o, T_p, T_c), enthalpy of gelatinization (ΔH_gel), peak height index (PHI) and higher gelatinization temperature range (R). PCA showed that LFP-48 and PG-3 flours were located at the far left of the score plot with a large negative score, while the AL-15 and AL-201 flours had large positive scores in the first principal component. Several significant correlations between functional, thermal and pasting properties were revealed, both by Pearson correlation and PCA. Pasting properties of the flours, measured using the rapid visco analyzer (RVA), also differed significantly. PPF were observed to have higher pasting temperature (PT), peak viscosity (PV), trough viscosity (TV), breakdown (BV), final viscosity (FV) and lower setback viscosity (SV) as compared to FPF.     

Physicochemical,thermal and sorption properties of nutritionally differentiated flours and starches

The aims of this work were to analyze physicochemical and thermal properties of ahipa and cassava flours and starches and to determine their water sorption isotherms and thermodynamic properties. Both flours are naturally gluten-free products, obtained by relatively simple procedures (grating or slicing). Ahipa flour gelatinized at lower temperature than cassava, indicating a better aptitude for cooking. Gelatinization temperatures of flours were higher than those of their starches. Water holding capacity of ahipa flours was significantly higher than those of cassava, leading the slicing process the highest values. Sorption isotherms were determined at 10, 20 and 30 °C. Experimental data were satisfactorily fitted using different mathematical models. Thermodynamic parameters associated with water adsorption process were calculated from GAB model, as well as the monolayer water content. All samples could be considered as products with an acceptable stability.     

Physicochemical and bread-making properties of air flow pulverized wheat and corn flours

The air flow pulverized grain flours were prepared from American wheat (AWF), Korean wheat (KWF), and corn (CRF) at 3 different grinding speeds, 9,000, 10,000, and 11,000 rpm. The effects of grinding speed on the physicochemical and bread making characteristics of resulting flours were investigated. Pulverization at low grinding speed produced the flour similar to those from conventional milling in particle size (80–100 μm). The higher speed grinding at 11,000 rpm produced grain flours with smaller particle sizes (20–30 μm) and higher amount of damaged starches. Accordingly, grinding speed increased water holding capacity, swelling power, and water solubility of the resulting grain flour, and also increased pasting properties. Gluten addition was needed for KWF (15% gluten) and CRF (30% gluten) to facilitate optimum bread making. The flour pulverized at high speed produced the KWF and CRF bread with the highest loaf volume and the lowest firmness.     

Fatty acids,mineral composition ond functional (bread and chapati) properties of high protein and high lysine barley lines

Six barley lines derived from corsses involving Hiproly (SV 73608×Mona⁵) and Riso 1508 with higher yield recipients V 43-42 and V 5681, along with the four parents, were analyzed for faty acids and mineral composition. Dough properties, bread and chapaties were charcterized by blending barley line (B82503) at 2.5-25% with bread wheat flour (pak 81). Fatty acid contents were myristic acid, 0.60-1.16%; palmitic acid, 16.68-20.84%; stearic acid, 1.30-3.33% and degree of unsaturation 1.40-1.50%. The derived lines contained similar amounts of essential fatty acids. Significant variation for magnesium, copper, zinc, phosphorus and potassium was observed but overlapped among the lines and parents. The calciu, iron, and manganese showed non-significant differences among lines and parents. Blending up to 10% barley flour with bread wheat flour gave farinograph characteristics comparable to those of pure wheat flour, but increasing the proportion of barley beyond this decreased the mix time and dough stability. Breadbaking tests verfied that up to 10% barley could be mixed with wheat without adversely affecting loaf volume and other quality attributes. For chapati making up to 20% barley could be blended into the wheat, yet yield acceptable quality.     

Physicochemical properties of Pinhão (Araucaria angustifolia, Bert, O. Ktze) starch phosphates

Physicochemical properties of pinhão (seeds of Paraná pine) starch phosphates were evaluated and compared to corn starch phosphates. The phosphorylation process used yielded starch phosphates with three different degrees of substitution (DS): low (0.015), medium (0.07) and high (?0.12). Medium and high DS starch phosphates had higher cold water binding capacity, swelling power, and paste clarity, but lower paste syneresis (at 5 °C and after freeze-thaw cycles) than native starches (P<0.05). Low, medium, and high DS corn starches had higher solubility than native starches (3.8-, 8-, and 6-fold higher; P<0.05), but the solubility of pinhão starch increased only in medium DS starch phosphates (3-fold higher; P<0.05). Low DS starch phosphates had viscosity curves similar to native starches. In contrast, medium and high DS starch pastes had peak viscosity at room temperature, reached the minimum viscosity when heated to 95 °C, and had low setback.     

Physicochemical properties of potato and cassava starches and their mutants in relation to their structural properties

Physicochemical properties [swelling power (SP), pasting behaviour and retrogradation] of five wild type (wt), five amylose free (amf), four high-amylose (ha) potato starches (ps) and one wt and amf cassava starch (cs) were investigated. While swelling of wtps occurred in two phases, amfps showed a very fast swelling and no gel of swollen granules was observed at higher temperatures (>90 °C). Haps underwent only restricted swelling. SP of cassava starches were lower than those of potato starches. Wtps leached mainly amylose (AM) during heating at low temperatures. Molecules of higher molecular weight (MW) leached out at higher temperatures. Longer amylopectin (AP) chains [degree of polymerisation (DP) > 18] inhibited swelling while short chains (DP < 14) favoured swelling. Starch pasting behaviour of 5.0 and 8.0% starch suspensions was studied using Rapid Visco Analyser (RVA). For 5.0% suspensions, increased levels of high-MW AP and decreased levels of AM molecules led to higher peak viscosity. Longer AP chains (DP > 18) depressed peak viscosity, while short chains (DP < 14) increased peak viscosity for both concentrations. At 8.0%, peak viscosity increased with starch granule size. After 1 day of storage of gelatinised starch suspensions, wtps and especially amfps showed only limited AP retrogradation. In contrast, the high enthalpies of retrograded AP (ΔH_retro) and peak and conclusion temperatures of retrogradation (T_p,retro and T_c,retro) of haps suggested partial cocrystallisation between AM and AP. Chains with DP 18–25 seemed to be more liable to AP retrogradation. Wtcs and amfcs did not retrograde at room temperature.     

Physicochemical and functional properties of full fat and defatted cashew kernel flours

Full fat and defatted cashew kernel flours were prepared and analysed for their physicochemical and functional properties. There were significant increase in protein and carbohydrate contents of the flour as a result of defatting. The defatted flour possessed higher Ca, P, Na and K contents. It had improved gel strength, foaming and emulsion properties. Foam capacity for the full fat and defatted flours increased from 42% to 50% and 55% to 57% with increased NaCl concentration up to 0.25 and 0.05  m , respectively. The foam capacity and stability of the flours were also pH dependent. The emulsion activity and stability of both flours decreased with increasing NaCl concentration. Minimum and maximum protein solubility were at pH 4 and 8, respectively for the full fat and defatted flours. These results suggest that defatted cashew flour may have potential application as a functional ingredient and as a supplement in foods.     

Factor analysis of the functional properties of rice flours from mutant genotypes

A set of 27 waxy rice genotypes and 52 rice genotypes with medium and high amylose contents were screened for various functional properties of flour. In this study, 68 genotypes containing various amylose contents (1.2–30.4%) were mutants of the rice variety TNG67 widely grown in Taiwan. The proximate composition, pasting, thermal and textural properties of rice flours were determined and analysed with factor analysis to assess the genetic differences. A wide variation in various functional properties was observed. Factor analysis indicated that four factors relating to amylose content, gel textural, gelatinization and protein content could explain 80% of the variability among 79 rice flours. Correlation studies and scatter diagrams also indicated the larger role of amylose with respect to protein and lipid in determining the rice flour quality. The present study can be used for readily identifying differences between rice genotypes for eating/cooking quality.     

Effect of ground corn steeping on starch properties

Pasting and thermal properties, and microstructure of starch from ground corn (GS) steeped at 52 °C in sulphurous acid solution (0.20%) at different steep times (8, 16, 24, 32 and 40 h) were investigated. The isolated starch obtained by wet milling was characterised by determining pasting properties in Rapid Visco Analyser (RVA), retrogradation enthalpy in differential scanning calorimetry (DSC), and microstructure of granules in light (LM) and scanning electron microscopy (SEM). Milling before steeping and long steep time caused reduction in peak, hot paste, cool paste, breakdown and setback viscosities. Steep time provoked an increase in the retrogradation temperatures (onset and peak), whereas no significant differences were found in retrogradation enthalpy. Microstructure characteristics analysed by SEM showed many cracks and cavities on surface in samples steeped 8 h, whereas samples steeped 40 h showed a great alteration and disruption of their inner layer. LM with polarised light confirmed that starches retained birefringence with several differences depending on the steep time. The use of ground kernels allowed a better steep solution–endosperm interaction, which caused changes in rheological, thermal and microstructural starch characteristics.     

Gelation,thermal and pasting properties of pigeon pea (Cajanus cajan L.), dolichos bean (Dolichos lablab L.) and jack bean (Canavalia ensiformis) flours

This study evaluated the rheological, thermal and pasting properties of pigeon pea (PP), dolichos bean (DB) and jack bean (JB) legume flours and gels. Starch and protein contents were also measured and its molecular weight distribution was determined by electrophoresis. PP and DB showed the highest viscosities while JB had the highest pasting temperature. The minimum flour concentrations for gel formation were estimated at 6–8% for DB and PP and 10% for JB. Above these concentrations all flour suspensions heated to 95 °C led to gels with a solid-like behavior. Differential scanning calorimetry showed two endothermic peaks in all flours at 80–89 °C and 96–100 °C. Avrami model was successfully fitted to the hardening kinetics of PP and DB gels stored at 4 °C. The half-life times were 22 and 6 h for PP and DB respectively. PP and DB flours were able to form self-supporting gels and could be applied in the formulation of gel-like foods.     

Pre-treatment effect on the nutritional and functional properties of selected cassava-based composite flours

The low protein and lack of gluten in cassava (Manihot esculenta Crantz) are disadvantageous for its use for product development and is overcome through the use of composite flours incorporating cereal and/or legume flours. The functionality and nutritional attributes of cassava flour were altered in the present study by pre-treatment with termamyl and green gram amylase, pre-gelatinization and subsequent blending with cereals, legumes, bran sources etc. Malting of cassava flour with termamyl followed by pre-gelatinization reduced the starch and increased the sugar content of the mixes. Pre-gelatinization had little effect on the crude protein of the mixes; nevertheless, the fat content was higher by 0.15–1.0 units. Energy content was around 1176 and 1217 KJ/100 g for the rice bran added mixes from malted cassava, which slightly increased in the respective pre-gelatinized cassava mixes. The peak viscosity of termamyl treated cassava-based flour mixes was much lower than the respective gram amylase based mixes, indicating that the latter had much less amylolytic activity than termamyl and pre-gelatinization further reduced the viscosity. The very low viscosity for the enzyme treated cassava-based mixes was due to the inability for retrogradation of the hydrolyzed starch. Significant improvement in in vitro starch digestibility (IVSD) (enhancement by 5.0–16.0 units in termamyl treatment vs 5.0–9.0 units in gram amylase treatment) was observed for the pre-gelatinized mixes. Lowest IVSD (25–29 units) was for the two bran based mixes, suggesting its use in the nutrition therapy for controlling obesity linked diseases.

Industrial relevance

With the development in human society, the incidence of chronic diseases like diabetes, cancer, cardiovascular problems and conditions like obesity contributing to several diseases is on the increase. This has led to an increasing awareness and research efforts on the development of functional foods, pharmafoods etc, which have wide potential application in medical nutrition therapy. The present work aims at improving the nutritional and functional attributes of cassava through fortification with cereal and/ or legume flours, bran sources etc. and through pre- treatment with enzymes to improve the functionality and reduce the energy content. The study led to the development of cassava based composite flours with low starch digestibility, high protein content and low energy content which could be effectively utilized for developing designer foods for obese and diabetic people. Enhanced digestibility of pre- gelatinized malted flours from cassava finds potential application for the development of foods for geriatric and convalescent people.     

Physicochemical and functional properties of Caryota urens flour as compared to wheat flour

Starch digestibility, thermal, pasting and gelling properties of Caryota urens (CU) flour were investigated using wheat flour as reference. Amylose content of CU and wheat flour was 32.1% and 28.3%, respectively. CU flour had very low content of protein and lipid but had a high content of total starch (98.2%) and resistant starch (RS) [42.5%]. Gelatinisation temperature (78.5 °C) of CU flour was higher than wheat flour. Pasting behaviour of CU flour was similar to that of high swelling tuber and root and waxy starches. CU flour retrograded to a greater extent than wheat flour. Very specific gelling behaviour was noticed for CU flour where it produced significantly harder gel with high paste clarity, fracture ability, adhesiveness, gumminess and chewiness. Expected glycaemic index (eGI) of CU and wheat flour was 92.4 and 100.4, respectively. CU flour had high eGI despite high content of resistant starch.