Relationship between the structure,physicochemical properties and in vitro digestibility of rice starches with different amylose contents

The in vitro digestibility and molecular and crystalline structures of rice starches (Long-grain, Arborio, Calrose, and Glutinous) differing in amylose content were investigated and the relationship between the structure and in vitro digestibility of starch was studied. Long-grain showed the highest amylose content (27.2%), whereas Glutinous showed the lowest amylose content (4.2%). Long-grain had the highest average amylopectin branch chain length (18.8) and proportion (8.7%) of long branch chains (DP ≥ 37), and the lowest proportion (26.9%) of short branch chains (DP 6–12). Among the non-waxy rice starches (Long-grain, Arborio, and Calrose), Calrose had the lowest average chain length (17.7) and the lowest proportion (7.1%) of long branch chains (DP ≥ 37). The relative crystallinity of rice starch followed the order: Glutinous (33.5%) > Calrose (31.4%) > Arborio (31.0%) > Long-grain (29.9%). Long-grain had the highest gelatinization temperature and the lowest gelatinization temperature range, whereas Glutinous showed the highest gelatinization temperature range and gelatinization enthalpy. Arborio had the highest melting enthalpy for amylose–lipid complex among the tested rice starches. Pasting temperature, setback, and final viscosity increased with increasing amylose content, whereas the peak viscosity and breakdown showed negative correlations with amylose content. The rapidly digestible starch (RDS) content of the tested rice starches followed the order: Glutinous (71.4%) > Calrose (52.2%) > Arborio (48.4%) > Long-grain (39.4%). Contrary to this, the slowly digestible starch (SDS) and resistant starch (RS) contents showed an opposite trend compared to RDS. Digestibility (RDS, SDS, and RS) of the rice starches was significantly correlated (p ≤ 0.05) with amylose content, proportions of DP 6–12 and DP 13–24, relative crystallinity, intensity ratio (of 1047 cm⁻¹ to 1022 cm⁻¹ from Fourier transform infrared spectroscopy), swelling factor, amylose leaching, onset temperature of gelatinization, gelatinization temperature range, gelatinization enthalpy, pasting temperature, peak viscosity, breakdown, setback, and final viscosity.     

In vitro starch digestibility,expected glycemic index,and thermal and pasting properties of flours from pea,lentil and chickpea cultivars

In vitro starch digestibility, expected glycemic index (eGI), and thermal and pasting properties of flours from pea, lentil and chickpea grown in Canada under identical environmental conditions were investigated. The protein content and gelatinization transition temperatures of lentil flour were higher than those of pea and chickpea flours. Chickpea flour showed a lower amylose content (10.8–13.5%) but higher free lipid content (6.5–7.1%) and amylose–lipid complex melting enthalpy (0.7–0.8 J/g). Significant differences among cultivars within the same species were observed with respect to swelling power, gelatinization properties, pasting properties and in vitro starch digestibility, especially chickpea flour from desi (Myles) and kabuli type (FLIP 97-101C and 97-Indian2-11). Lentil flour was hydrolyzed more slowly and to a lesser extent than pea and chickpea flours. The amount of slowly digestible starch (SDS) in chickpea flour was the highest among the pulse flours, but the resistant starch (RS) content was the lowest. The eGI of lentil flour was the lowest among the pulse flours.     

Starch affecting anti-staling agents and their function in freestanding and pan-baked bread

Anti-staling agents with different mechanisms were added to a normal white wheat bread to investigate the relation between bread staling, amylopectin retrogradation and water-related properties (i.e. water content and distribution between crumb and crust). Bread was baked both as pan-baked and freestanding loaves. The anti-staling agents maltogenic α-amylase, distilled monoglyceride and lipase had a direct influence on starch retrogradation, whereas gluten and waxy wheat flour diluted the amylopectin content or changed the ratio between amylose and amylopectin. The degree of staling was measured as the firmness and springiness, together with two new methods, crumbliness and cutability. In addition, the degrees of amylopectin retrogradation and amylose–lipid complex formation were analyzed by differential scanning calorimetry, and the water content, water loss and water migration were measured. The addition of α-amylase improved most staling parameters, although the changes were not as large as expected. Furthermore, monoglyceride and lipase increased the formation of amylose–lipid complexes, but only lipase gave better results regarding the specific volume and firmness. Increased amylose–lipid complex formation was seen to increase water migration from crumb to crust. Adding 10% waxy wheat flour appeared to lead to a slight overall improvement i.e. lower water migration and better cutability. Adding gluten or 3% waxy wheat flour only improved the specific volume. The method of baking the loaves, i.e. freestanding or pan-baked, had a greater influence than the anti-staling agents, which shows that bread quality is not always improved by starch affecting anti-staling agents without process changes.     

Genotypic diversity in physico-chemical,pasting and gel textural properties of chickpea (Cicer arietinum L.)

Twenty chickpea cultivars were evaluated for genetic diversity in seeds (physical, hydration and cooking), flours (composition, pasting and gel textural) and starch (swelling, thermal, amylose content and amylopectin structure) properties. Frequency distribution and principal component analysis revealed significant differences among the cultivars studied. Pasting temperature, peak viscosity, breakdown, final viscosity and setback of flours ranged from 75.0 to 87.1 °C, 564 to 853 cP, 32 to 123 cP, 573 to 969 cP, and 84 to 185 cP, respectively. Amylose content of starch ranged from 28.26% to 52.82%. Amylopectin unit chains of DP 6–12, 13–18, 19–24 and 25–30 ranged from 36.2% to 43.25%, 36.44% to 38.68%, 14.86% to 18.22% and 4.95% to 6.9%, respectively. To establish the relationships between different properties Pearson correlation coefficients (r) were computed. Cluster analysis for grain and flour characteristics was also done to see the association between chickpea cultivars.     

Composition,molecular structure,and physicochemical properties of starches from two grass pea (Lathyrus sativus L.) cultivars grown in Canada

The morphology, molecular structure and physicochemical properties of starches from two cultivars (NC8A97, Lath 96) of grass pea (Lathyrus sativus L.) were examined. In both cultivars, starch granules were irregular to oval to round to elliptical shaped, with smooth surfaces. No significant differences was observed between the cultivars with respect to mean granule diameter (26.3–27.3 μm), mean granule length (32–34.5 μm), amylose content (37.95–38.30%), bound lipid content (0.08%), amylopectin chain length distribution, average chain length (19.2) and X-ray diffraction pattern (‘C’ type). However, NC8A97 and Lath 96 starches differed significantly with respect to the degree of crystallinity (Lath 96 > NC8A97), B-polymorphic content (Lath 96 > NC8A97), granular swelling (NC8A97 > Lath 96), extent of amylose leaching (NC8A97 > Lath 96), peak viscosity (Lath 96 > NC8A97), shear stability (Lath 96 > NC8A97), set-back (NC8A97 > Lath 96) and susceptibility towards enzyme and acid hydrolysis (NC8A97 > Lath 96). The results showed that physicochemical properties of the grass pea starches were influenced by the extent of interaction between starch chains (Lath 96 > NC897) in the amorphous regions, amount of crystallites (NC8A97 > Lath 96) and crystallite heterogeneity (NC8A97 > Lath 96).     

Structural characterizations and digestibility of debranched high-amylose maize starch complexed with lauric acid

Structural characterizations and digestibility of debranched high-amylose maize starch complexed with lauric acid (LA) were studied. The cooked starch was debranched by using pullulanase and then complexed. Light microscopy showed that the lipids complexed starches had irregularly-shaped particles with strong birefringence. Gel-permeation chromatograms revealed that amylopectin degraded to smaller molecules during increasing debranching time, and the debranch reaction was completed at 12 h. Debranching pretreatment and prolonged debranching time (from 2 h to 24 h) could improve the formation of starch lipids complex. X-ray diffraction pattern of the amylose–lipid complexes changed from V-type to a mixture of B- and V-type polymorphs and relative crystallinity increased as the debranching time increased from 0 to 24 h. In DSC thermograms, complexes from debranched starch displayed three separated endotherms: the melting of the free lauric acid, starch–lipid complexes and retrograded amylose, respectively. The melting temperature and enthalpy changes of starch–lipid complex were gradually enhanced with the increasing of debranching time. However, no significant enthalpy changes were observed from retrograded amylose during the starch–lipid complex formation. Rapidly digestible starch (RDS) content decreased and resistant starch (RS) content increased with the increasing of debranching time, while the highest slowly digestible starch (SDS) content was founded at less debranching time of 2 h. The crystalline structures with dense aggregation of helices from amylose-LA complex and retrograded amylose could be RS, while SDS mostly consisted of imperfect packing of helices between amylopectin residue and amylose or LA.     

Impact of annealing on the molecular structure and physicochemical properties of normal,waxy and high amylose bread wheat starches

Starch from normal (CDC teal), high amylose (line 11132) and waxy (99 WAX 27) bread wheat cultivars was isolated and its morphology, composition, structure and properties were studied before and after annealing. Granule diameters, total phosphorus, total amylose, lipid complexed amylose chains, crystallinity, gelatinization temperature range, gelatinization enthalpy, swelling factor (at 90 °C), and amylose leaching (at 90 °C), in the above starches ranged from 2–38 μm, 0.007–0.058%, 26.9–32.3%, 13.4–18.7%, 28.6–42.8%, 12.7–14.3 °C, 11.3–13.3 J/g, 27.6–72.2 and 22.2–26.2%, respectively. Peak viscosity, thermal stability, set-back and susceptibility towards acid hydrolysis followed the order: 99WAX27 > CDC teal > 11132, 11132 > CDC teal > 99WAX27, CDC teal > 99 WAX 27 > 11132, and 99WAX27 > 11132 > CDC teal, respectively. Susceptibility towards α-amylase hydrolysis followed the order: 99 WAX 27 > 11132 > CDC teal (<24 h) and 11132 > CDC teal > 99WAX27 (>24 h). The extent of retrogradation measured by spectroscopy and differential scanning calorimetry followed the order: 11132 > CDC teal > 99WAX27 and 99WAX27 > CDC teal > 11132, respectively. In all starches, concentration of amylose, lipid complexed amylose chains, gelatinization temperature range, swelling factor, amylose leaching, peak viscosity, final viscosity, set-back, light transmission, susceptibility towards α-amylase and acid hydrolysis and the proportion of small (2–8 μm) B-type granules decreased on annealing. Thermal stability and crystallinity increased on annealing. In all starches, gelatinization, enthalpy, retrogradation rate and amylopectin chain length distribution remained unchanged on annealing. Pores and indentations were formed on the granule surfaces of CDC teal and 99WAX27 starches on annealing.     

Effect of extrusion conditions on physicochemical and sensorial properties of corn-broad beans (Vicia faba) spaghetti type pasta

Corn-broad bean spaghetti type pasta was made with a corn/broad bean flour blend in a 70:30 ratio, through an extrusion-cooking process (Brabender 10 DN single-screw extruder with a 3:1 compression ratio). The effect of temperature (T = 80, 90 and 100 °C) and moisture (M = 28%, 31% and 34%) on the extrusion responses (specific consumption of mechanical energy and pressure) and the quality of this pasta-like product (expansion, cooking-related losses, water absorption, firmness and stickiness) was assessed. The structural changes of starch were studied by means of DSC and XRD. The extrusion-cooking process, at M = 28% and T = 100 °C, is appropriate to obtain corn-broad bean spaghetti-type pasta with high protein and dietary fibre content and adequate quality. The cooking characteristics and resistance to overcooking depended on the degree of gelatinisation and formation of amylose–lipid complexes. The critical gelatinisation point was 46.55%; beyond that point, the quality of the product declines.     

Formation of starch spherulites: Role of amylose content and thermal events

Commercial maize starches and potato starches of two cultivars differing in physicochemical composition (granule size distribution; amylose to amylopectin ratio) and crystallinity were heated to 180 °C and then cooled by fast quench using a differential scanning calorimeter (DSC), in order to produce spherulitic starch morphologies. Among the raw maize starches, waxy maize starch had highest relative crystallinity (49%) whereas a lowest crystallinity of 33–39% was calculated for high-amylose maize starches. Potato starches showed a relative crystallinity of 50%. The temperatures and enthalpies of gelatinisation and melting varied among all the starches. High-amylose maize starches showed higher transition temperatures of gelatinisation (T_gel), whereas waxy maize starch had lowest T_gel and enthalpy of gelatinisation (ΔH_gel). Similarly, a considerable variation in parameters related with crystalline melting (T_m1, T_m2 and ΔH_m1, ΔH_m2) was observed for different starches. The superheated gels of different starches treated using DSC were subjected to polarised microscopy, to confirm the formation of spherulites. Both the high-amylose starch gels showed the presence of spherulites exhibiting birefringence and a weak crystalline pattern. No birefringence was observed for waxy maize starch gel, while potato starch gels had some birefringence. The particle size distribution of high-amylose maize starch gels analysed through Zetasizer showed the sizes of spherulitic particles fall in the range of 300 nm–900 nm. The scanning electron micrographs of the dried high-amylose maize starch gels showed the presence of round spherulites consisting of several aggregated spherulitic particles. Amylose content and melting of crystallites during heating play an important role during recrystallisation of amylose (spherulite morphologies).     

Physico-chemical properties of potato starches

Starches were isolated and characterised from 10 potato cultivars grown under the same conditions (with a commercial starch for reference). The chemical composition revealed some differences amongst the starches with protein ranging from 0.30% to 0.34%, amylose 25.2% to 29.1% and phosphorus 52.6–66.2 mg 100 g⁻¹. High performance size-exclusion chromatography (HPSEC) fractionation of isoamylase debranched amylopectin showed that the amylopectin molecules were less branched and consisted of more B1, but less A-chains, than cereal starches. Gelatinisation onset (T_o), peak (T_p) and conclusion (T_c) temperatures of the native potato starches ranged from 58.7 to 62.5 °C, 62.5 to 66.1 °C and 68.7 to 72.3 °C, respectively, whilst the gelatinisation enthalpies ranged from 15.1 to 18.4 J g⁻¹. The gelatinisation temperatures of the starches increased in common with the amounts of short and intermediate sized amylopectin chains. The ¹³C magic angle spinning nuclear magnetic resonance (¹³C CP-MAS NMR) and wide angle X-ray diffraction (XRD) data (30.6% ± 0.22% crystallinity on average) showed little variance amongst the samples. Particle sizing results, however, revealed more variance (20.6–30.9 μm mean diameter). Overall, these data reveal the subtleties of cultivar specific variation against a background of constant environmental conditions.     

Physical–chemical and functional properties of maca root starch (Lepidium meyenii Walpers)

The starch of maca (Lepidium meyenii Walpers) presented oval and irregular morphology, with granule size between 7.4 and 14.9 μm in length and 5.8 and 9.3 μm in diameter. The isolated starch showed the following features: purity of 87.8%, with 0.28% lipids, 0.2% fibre and 0.12% fixed mineral residue, and no protein detected; the ratio between the amylose and amylopectin contents were 20:80; the solubility at 90 °C was 61.4%, the swelling power was 119.0 g water/g starch and the water absorption capacity was 45.9 g water/g starch; the gel turbidity rose 44% during the storing time; the gelatinization temperature was 47.7 °C and the transition enthalpy 6.22 J/g; the maximum viscosity reached 1260 UB at 46.4 °C, with breakdown, setback and consistence of 850, 440 and −410 UB, respectively. The low gelling temperature and the stability during gel refrigeration could be adequate for foods requiring moderate temperature process, but not for frozen food.     

Studies on tuber and root starches. I. Structure and physicochemical properties of innala (Solenostemon rotundifolius) starches grown in Sri Lanka

Starches from two cultivars (Bola and Dik) of innala tubers (Solenostemon rotundifolius) grown in the same location and under identical environmental conditions in Sri Lanka was isolated and some of the characteristics determined. The yield of starch from both cultivars was 16.0% on initial tuber weight. The shape of the granules in both cultivars was dome shaped and hemispherical with 4–5 slightly concaved facets. Pores were found randomly distributed over the surface of both starch granules. The amylopectin branch chain length distribution was nearly similar for both starches. However, the starches differed with respect to granular swelling, amylose leaching, susceptibility towards acid and enzyme hydrolysis, gelatinization characteristics, pasting properties and retrogradation kinetics. The results showed that differences in amylose content, lipid complexed amylose chains, relative crystallinity and extent of interaction between amylose chains in the amorphous regions of the granule had a substantial impact on the observed differences in physicochemical properties.     

Impact of structural changes due to heat-moisture treatment at different temperatures on the susceptibility of normal and waxy potato starches towards hydrolysis by porcine pancreatic alpha amylase

The objectives of this study were to determine the impact of structural changes within the amorphous and crystalline domains of normal potato (NP) and waxy potato (WP) starches subjected to heat-moisture treatment (HMT) at 80, 100, 120 and 130 °C for 16 h at a moisture content of 27% and to determine the impact of structural changes at each of the above temperatures on the susceptibility on hydrolysis by porcine pancreatic α-amylase (PPA). The results showed that structural changes due to HMT were influenced by differences in starch chain mobility at the different temperatures of HMT. Starch chain mobility in turn was influenced by the interplay between the extent to which B-type crystallites were transformed into A + B-type crystallites, kinetic energy imparted to starch chains and amylose content. The main type of structural changes influencing physicochemical properties at the different temperatures of HMT was starch chain interactions (at 80 and 100 °C), disruption of hydrogen bonds between amylose (AM)–amylopectin (AMP) and AMP–AMP chains (at 120 and 130 °C), disorganization of AMP chains near the vicinity of the hilum (at 100, 120 and 130 °C) and formation of interrupted helices (at 130 °C). The susceptibility of NP and WP starches towards α-amylase decreased at 80 °C, but increased in the range of 100 to 130 °C. This suggested that α-amylase hydrolysis of HMT starches was influenced by the interplay of: 1) amount of A-type crystallites, 2) starch chain interactions and 3) changes to double helical conformation. Differences in granule morphology in PPA hydrolyzed NP and WP starches were largely influenced by the higher granular swelling in the latter. NP and WP starches exhibited heterogeneity in degradation (NP > WP) in both their native and HMT states.     

Effect of hydroxypropyl β-cyclodextrin on physical properties and transition parameters of amylose–lipid complexes of native and acetylated starches

The effect of hydroxpropyl β-cyclodextrin (HPβ-CD) on physical properties and digestibility of wheat, potato, waxy maize and high-amylose maize starches before and after acetylation was studied. Effect of HPβ-CD on amylose–lipid complexes in native and acetylated potato starches synthesized using α-lysophosphatidylcholine was also studied. Acetylation increased swelling factor, amylose leaching, peak viscosity and susceptibility to α-amylase hydrolysis, but decreased gelatinization temperature and enthalpy and gel hardness in all starches. HPβ-CD markedly increased swelling factor and amylose leaching in native and acetylated wheat starches but had little or no impact on other starches. Wheat starch gelatinization enthalpy decreased in the presence of HPβ-CD but gelatinization temperature of all the starches was slightly increased. HPβ-CD had no influence on enzymatic hydrolysis. Melting enthalpy of amylose–lipid complex in both native and acetylated wheat starches was decreased by HPβ-CD. Acetylation also decreased the melting enthalpy of amylose–lipid complex in wheat starch. Similar trend of thermal transitions was observed in the presence of HPβ-CD for the amylose–lipid complexes synthesized in potato starch. Acetylation reduces the complex formation ability of the amylose polymer. Similar to gelatinization, acetylation widened the melting temperature range of amylose–lipid complexes while shifting it to a lower temperature. Higher swelling and amylose leaching, and decreased gelatinization temperature and enthalpy resulting from acetylation of wheat starch is consistent with its influence on starch hydration. Similar effects resulting from the inclusion of HPβ-CD were consistent with the disruption of amylose–lipid complex by HPβ-CD which promotes granular hydration.     

Effect of heat-moisture treatment on the formation and physicochemical properties of resistant starch from mung bean (Phaseolus radiatus) starch

Mung bean starch was subjected to a range of heat-moisture treatments (HMT) based on different moisture contents (15%, 20%, 25%, 30%, and 35%) all heated at 120 °C for 12 h. The impact on the yields of resistant starch (RS), and the microstructure, physicochemical and functional properties of RS was investigated. Compared to raw starch, the RS content of HMT starch increased significantly, with the starch treated at 20% moisture having the highest RS content. After HMT, birefringence remained at the periphery of the granules and was absent at the center of some granules. The shape and integrity of HMT starch granules did not change but concavity was observed under scanning electronic microscopy. Apparent amylose contents of HMT starch increased and the HMT starch was dominated by high molecular weight fraction. Both the native and HMT starches showed A-type X-ray diffraction pattern. Relative crystallinity increased after HMT. The gelatinization temperatures (To, Tp, and Tc), gelatinization temperature range (Tc–To) and enthalpies of gelatinization (ΔH) increased significantly in HMT starch compared to native starch. The solubility increased but swelling power decreased in HMT starches. This study clearly shows that the HMT exhibited thermal stability and resistance to enzymatic hydrolysis owing to stronger interactions of starch chains in granule.     

The effect of acid dextrinisation on enzyme-resistant starch content in extruded maize starch

The enzyme-resistant starch (ERS) content in processed high amylose and regular maize starches has been studied, with and without acid dextrinisation. The physicochemical and structural characteristics of the starches were analysed using a variety of techniques. The increase in ERS in high amylose maize starch with dextrinisation was related to the formation of a critical molecular weight fraction (MW ∼ 20,000) that could rearrange structurally. Further dextrinisation reduced the processed starch MW to below where it could still form ERS. Regular maize starch containing less than 30% amylose did not increase its resistance to amylase digestibility with acid dextrinisation, probably due to impairment of amylose rearrangement by the numerous branched amylopectin chains. The ERS, which is likely to form during the enzyme-digestion process, is a linear molecule with a maximum degree of polymerisation (DP) of 30, irrespective of the starch source, processing conditions applied or type and amount of acid used.     

Physicochemical,thermal, and pasting properties of flours and starches of eight Brazilian maize landraces (Zea mays L.)

Both genetic and environmental factors create significant variation in the amount and quality of maize landrace constituents. Details on the flours and starch characteristics have not been fully investigated. The physicochemical, pasting and thermal properties of 8 promising cultivars were assessed in this study and those properties were correlated. Higher values of swelling and solubility (RJ – 13.14%; 14.39%), lipid content (MG – 5.53%), WBC (PR – 18.89%), and amylose content (PR – 27.43%) were found for those genotypes. Lower onset temperatures of gelatinization (To) were observed for RX-F1 (66.1 °C) as RX-F1 (68.7 °C) genotype showed the lower pasting temperatures. A wide range of viscosity values was found among the maize landraces (MG-F0, 343 mPa s and RJ-F1, 175 mPa s) as well as for the retrogradation (R8C-F1, 796 mPa s and RX-F1, 22 mPa s). ATR-FTIR spectroscopy revealed amylose, amylopectin, lipids, and proteins as major flours constituents and their differences were discriminated by PCA analysis.     

Microstructure & rheology of mixed colloidal dispersions: Influence of pH-induced droplet aggregation on starch granule–fat droplet mixtures

The creation of high quality reduced-fat food products is challenging because the removal of fat adversely affects quality attributes, such as appearance, texture, and flavor. This study investigated the impact of pH-induced droplet aggregation on the properties of model food systems consisting of fat droplets and starch granules. Oil-in-water emulsions (2 wt.% oil) containing whey-protein coated lipid droplets aggregated extensively when heated (90 °C, 5 min) at pH values around their isoelectric point (pH 5) but not at lower (pH 3.5) or higher (pH 7) values, which was attributed to changes in electrostatic repulsion. The physicochemical properties of mixed lipid droplet–starch dispersions (2 wt.% oil, 4 wt.% starch) prepared under similar conditions (pH 3.5, 5, and 7; 90 °C for 5 min) were also measured. At pH 5, extensive lipid droplet aggregation was observed in mixed systems, which led to a large increase in their yield stress and apparent viscosity when compared to mixed systems at pH 3.5 and 7. These results show that the rheological properties of mixed fat droplet–starch granule suspensions can be modulated by controlling the electrostatic interactions between the fat droplets so as to change their flocculation state. This study has important implications for fabricating high quality reduced-fat products with desirable sensory attributes.     

Prediction of sweetpotato starch physiochemical quality and pasting properties using near-infrared reflectance spectroscopy

A rapid predictive method based on near-infrared reflectance (NIR) spectroscopy (NIRS) was developed to measure sweetpotato starch physiochemical quality and pasting properties. The starch samples were scanned by NIRS and analyzed for quality properties by reference methods, respectively. Results of statistical modeling indicated that NIRS was reasonably accurate in predicting amylose content (AC), amylose percent (AP), total starch content (TSC), protein content (PRC), phosphorus content (PHC), solubility (SOL), swelling power (SP), average granule diameter (AGD), big granule percent (BGP), small granule percent (SGP), crystallinity (CRY), peak viscosity (PKV), hot paste viscosity (HPV), setback (SB), and pasting temperature (P_temp) with high coefficients of determination (RSQ = 0.85–0.92) and relatively low standard errors of prediction. The results showed that NIR analysis was sufficiently accurate and effective for rapid evaluation of starch physicochemical properties in sweetpotato. The NIR-based protocol developed in this study can be used for screening large number of starch samples in food enterprises and sweetpotato breeding programs.     

Crystalline,thermal and textural characteristics of starches isolated from chestnut (Castanea mollissima Bl.) seeds at different degrees of hardness

The crystalline, thermal and textural properties of chestnut starches (CSs I–V) at 0%, 25%, 50%, 75% and 100% degrees of hardening (DHs) were investigated in this work. CS I had a structure of C-type crystallinity. With the increase of DH, more B-type crystalline regions and amylose–lipid complexes were formed. The gelatinisation temperature of CS and melting temperature of amylose–lipid complexes were not significantly changed as DH increased. However, a significant (P < 0.05) increase of ΔH was observed for CS V. The texture analysis indicated that CS V had a lower firmness, adhesiveness and a higher cohesiveness than CS I. The correlation test confirmed the significant correlations between ΔHs of gelatinisation and melting of amylose–lipid complexes, firmness, adhesiveness, cohesiveness and DH. All the results indicated that degradation of CS should be one of important mechanisms for the hardening of chestnut, especially in the late period of hardening.