Physicochemical Characteristics of Starches from Unripe Fruits of Mango and Banana

Mango and banana starches were isolated from unripe fruits and their morphology; thermal and pasting properties; molar mass and chain length distribution were determined. Mango starch granules were spherical or dome‐shaped and split, while banana starch had elongated granules with a lenticular shape. Amylopectin of both fruit starches had a lower molar mass than maize starch amylopectin; however, mango amylopectin had the highest gyration radius. Banana amylopectin showed the lowest percentage of short chains [degree of polymerization (DP) 6–12] and the highest level of long chains (DP ≥ 37); mango amylopectin presented the highest fraction of short chains, but the level of longest chains was intermediate between those of banana and maize amylopectins. Banana starch presented the highest average gelatinization temperature followed by mango starch and maize starch had the lowest value; a similar pattern was found for the gelatinization enthalpy. The two fruit starches had a lower pasting temperature than maize starch, but the former samples showed higher peak and final viscosities than maize starch. Structural differences identified in the fruit starches explain their physicochemical characteristics such as thermal and pasting behavior.     

Structure and Viscoelastic Properties of Starches Separated from Different Legumes

A comparison between the morphological, structural, thermal and viscoelastic properties of starches separated from pigeon pea, chickpea, field pea, kidney bean and blackgram was made. The shape of the starch granules in the different legumes varied from oval to elliptical or spherical. X-ray diffraction of the legume starches indicated a typical C-pattern (mixture of A- and B-type). Granules of blackgram and pigeon pea starch had a higher degree of crystallinity than those of field pea and kidney bean starches. Apparent amylose content of field pea, kidney bean, chickpea, blackgram and pigeon pea starch was 37.9%, 36.0%, 34.4-35.5%, 32.9-35.6% and 31.8%, respectively. Distribution of isoamylase-branched materials among the starches revealed that the proportions of long and short side chains of amylopectin ranged between 13.6-18.5% and 41.7-46.5%, respectively. Field pea and kidney bean starch had the highest apparent amylose content and the lowest amount of long side chains of amylopectin, respectively. Blackgram and pigeon pea starch possessed higher proportions of both long and short side chains of amylopectin than field pea and chickpea starches. The onset, peak and conclusion temperatures of gelatinization (T_o T_p and T_c, respectively) were determined by differential scanning calorimetry. T_o and T_c ranged from 59.3 to 77.3°C, 66.8 to 79.6°C, 55.4 to 67.6°C and 68.3 to 69.3°C, respectively, for chickpea, blackgram, field pea and kidney bean starch. The enthalpy of gelatinization (ΔH_gel) of field pea, kidney bean, chickpea, blackgram and pigeon pea starches was 3.6, 3.0, 2.6-4.2, 1.6-1.7 and 2.6 J/g, respectively. Pastes of blackgram and pigeon pea starches showed lower storage and loss shear moduli G′ than field pea, kidney bean and chickpea starches. The changes in moduli during 10 h at 10°C revealed retrogradation in the order of: field pea> kidney bean> chickpea> blackgram> pigeon pea starch. In blackgram and pigeon pea starches, the lower proportion of amylose plus intermediate fraction and higher proportion of short and long side chains of amylopectin are considered responsible for the higher crystallinity, gelatinization temperature and enthalpy of gelatinization.     

Pisum sativum and Vicia faba Carbohydrates: Structural Studies of Starches

The fine structure of laboratory purified broadbean and smooth pea starches, with an amylose content of 32-34%, has been studied by pullulanase debranching, before or after beta-amylolysis, and by the properties of the chemically fractionated amylose and amylopectin. The enzymatic study has shown the presence of the three chain populations (DP > 60, 45 and 15) observed with other starches. The linear DP 15 and 45 chains occur in a ratio of 8.5 for broadbean and 9.75 for pea, which indicates an amylopectin similar to cereal starches. The λ_max, beta-amylolysis limit and intrinsic viscosity of the two amylopectins confirm the cereal-like nature. The two amylose components are not completely linear according to their beta-amylolysis limit of 81.5% which corroborates the in complete debranching of the total starch. The physical structure, studied by X-ray diffractometry, is of C-type. By submitting legume starch granules to mild acid hydrolysis (lintnerization), a residue has been obtained from both starches, which has an increase in the crystalline fraction, with a tendency towards the A-type pattern for broadbean and the B-type for pea. The crystallites are mainly formed of linear chains (CL 15) with some singly branched material (DP 25). Gelatinization of starch granules occurs at 44-65-86°C for broadbean with a heat of gelatinization of 3.8 cal g^?1 and at 48-61-80°C for pea with a heat of gelatinization of 3.2 cal g^?1.     

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.     

Physicochemical Properties of Sweetpotato Starches with Different Gelatinization Temperatures

Physicochemical properties of five sweetpotato starches differing in gelatinization temperature were examined. The gelatinization temperature of Koganesengan starch, an ordinary cultivar of sweetpotato in Japan, was 73.6°C, whereas those of the other starches were measured to be 71.6°C for Kyukei 96162–1, 65.8°C for Kyushu No.127, 63.9°C for Kyukei 240, and 54.9°C for Quick Sweet. Some relationships of the primary structural properties with the gelatinization temperature have been found. As the gelatinization temperature decreased: i) the content of phosphate groups attached to the glucosyl residues decreased, ii) the amylose content, which was determined as difference in long chains of debranched original starch and of its amylopectin, decreased, iii) the proportion of unit chains with DP > 100 in the amylopectin fraction increased, iv) the proportion of unit chains with DP 6 to 10 in the amylopectin fraction increased, whereas that of unit chains with DP 12 to 24 decreased, v) the B‐type crystallinity of the starch granules was enhanced, and vi) the proportion of longer chains constituting each Nägeli amylodextrin increased. Moreover, it was found that thin pastes of the low temperature‐gelatinizing starches retrograded slower during cold storage than the ordinary starch. Among the starches, Quick Sweet starch granules, having the lowest gelatinization temperature, were digested rapidly by pancreatin.     

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.     

Effect of Amylopectin Structure on the Gelatinization and Pasting Properties of Selected Yam (Dioscorea spp.) Starches

This study was aimed at elucidating the decisive structural parameters of amylopectin which govern the gelatinization or pasting behavior of yam starch dispersions, exemplified with four selected yam starches from Dioscorea alata and D. batatas with very similar amylose contents (32.2–34.6%). The results indicated that the yam amylopectins examined showed an average degree of polymerization (DP) of 3469–4474 anhydroglucose units (AGU), average chain length (CL) of 18.8–28.5 AGU, average exterior CL (ECL) of 11.8–16.4 AGU, average interior CL (ICL) of 6.0–11.1 AGU, and a noticeable proportion of extralong (> 100 AGU) and long (40–100 AGU) chains that gave the chain ratio r_(el+l)/s (the weight ratio of extralong and long chains to short chains) of 0.88–1.40. Generally, the yam amylopectin with a lower DP and NC possessed a greater CL, ECL, ICL, and r_(el+l)/s, associating with a higher blue value (BV) and maximal wavelength (λ_max) for their complexes with iodine. D. alata amylopectins exhibited a lower DP, longer chain lengths and greater r_(el+l)/s than the D. batata amylopectins. Statistically, r_(el+l)/s was decisive for the BV and λ_max; while CL and phosphate content were crucial for the gelatinization peak temperature and pasting viscosities of the yam starches examined. The role of swelling power or the volume fraction of dispersed remnants instead in governing the pasting viscosity was also mathematically explored.     

Chemical and Physical Properties of Kiwifruit (Actinidia deliciosa) Starch

Chemical and physical properties of kiwifruit (Actinidia deliciosa var. ‘Hayward’) starch were studied. Kiwifruit starch granules were compound, irregular or dome‐shaped with diameters predominantly 4–5 µm or 7–9 µm. Kiwifruit starch exhibited B‐type X‐ray diffraction pattern, an apparent amylose content of 43.1% and absolute amylose content of 18.8%. Kiwifruit amylopectins, relative to other starches, had low weight‐average molecular weight (7.4×10⁷), and gyration radius (200 nm). Average amylopectin branch chain‐length was long (DP 28.6). Onset and peak gelatinization temperatures were 68.9°C and 73.0°C, respectively, and gelatinization enthalpy was high (18.5 J/g). Amylose‐lipid thermal transition was observed. Starch retrograded for 7 d at 4°C had a very high peak melting temperature (60.7°C). Peak (250 RVU), final (238 RVU) and setback (94 RVU) viscosity of 8% kiwifruit starch paste was high relative to other starches and pasting temperature (69.7°C) was marginally higher than onset gelatinization temperature. High paste viscosities and low pasting temperature could give kiwifruit starch some advantages over many cereal starches.     

Chemometric Analysis of the Gelatinization and Pasting Properties of Long‐grain Rice Starches in Relation to Fine Structure

Chemometric tests were carried out to better understand the multidimensional facet of starch fine structure‐relationship concerning gelatinization and pasting properties. With Ward's hierarchical cluster analysis 20 long‐grain rice starch samples were sorted out into three clusters based on similarities in functional properties, particularly, paste peak (PV) and final viscosity (FV). The three clusters (arbitrarily named Clusters A, B, and C) exhibited a pasting profile trend of PV<FV, PV˜FV, and PV>FV, respectively. Cluster A samples were also lower in peak temperature, range and enthalpy of gelatinization, and swelling power. These attributes were associated with higher amylose content (AM), β‐amylolysis limit, and percentage of B1 chains (DP13‐24), but lower amylopectin weight‐average molar mass (M_w) and percentage of A chains (DP6‐12). A 5‐variable linear discriminant function correctly predicted 85% of the Ward's cluster membership of the individual cultivars. The discriminant function included the variables A, B1, and B2 (DP25‐36) chains, average chain length (ACL), and gyration radius (R_z). Fine structure variance was fully explained by a total of nine principal components, with the first three components cumulatively accounting for 74%. The leading variables included in the three rotated components pertained to amylopectin chain length distribution (A, B2, and B3+ or DP≥37 chains, and ACL) and amylopectin molar mass (M_w, R_z, and polydispersity). AM and M_w were loaded most frequently in the 4‐variable, best‐fit linear regression models for predicting gelatinization and pasting properties. A combination of at least two fine structure variables controls the functionality of rice starch.     

New Sweet Potato Line having low Gelatinization Temperature and altered Starch Structure

A new sweet potato breeding line, Kanto 116, was developed, featuring low gelatinization temperature and an altered starch fine structure. Starch granules from Kanto 116 showed an abnormal morphology characterized by cracking into granules. Starch content, amylose content and tuberous root appearance of Kanto 116 were similar to those of the control and the parents. Pasting temperatures of Kanto 116 starch determined by the Rapid Visco Analyser were 51.4 — 52.6 °C, approximately 20 °C lower than those of the control and parents starches. Onset, peak, and conclusion temperature of gelatinization, and gelatinization enthalpy of Kanto 116 starch determined by differential scanning calorimetry were 39.0 °C, 46.9 °C, 64.8 °C, and 8.8 J/g, respectively, and much lower than those of the control and parents starches. The chain‐length distribution of the amylopectin molecules, determined by high‐performance anion‐exchange chromatography, showed that Kanto 116 starch had a higher proportion of short chains (DP 6 — 11) and a lower proportion of chains between DP 12 — 28 than control and parent starches. The debranched β‐limit dextrin of Kanto 116 starch also showed that the proportion of both short and long B1 chains was different from those of the control and parents starches.     

Comparative study of three legume starches

Starch content of chickpea ( Cicer arietinum ), pigeon pea ( Cajanus cajan ) and bonavist bean ( Dolichos lablab ) was 58,52 and 50% respectively with recovery of 57.9, 48.1 and 49.0%. The amylose content was 33.5, 27.0 and 31.0%; amylose chain length was 1420,550 and 830 glucose units and amylopectin chain length was 29, 27 and 28 glucose units for chickpea, pigeon pea and bonavist bean respectively. Chickpea starch granules ranged from large oval shaped (21 × 30 pm) to small spherical (13 pm in diameter); pigeon pea from (35 × 42 pm) to 15.2 pm and bonavist bean (35 × 42 pm) to 15.2 pm. The gelatin-ization temperature range was 67–76°C for chickpea, 71–78°C for pigeon pea and 78–80°C for bonavist bean starch. The swelling power for chickpea, pigeon pea and bonavist bean at 95°C were 17, 18.5 and 22.5% respectively. The legumes showed a single-stage and somewhat restricted swelling. Solubility curves for legume starches showed a similar pattern and indicated that they have higher solubility at elevated temperatures than wheat starch. The liquefaction characteristics showed that chickpea has the highest resistance to cooking and was the most sensitive to a-amylase. The three legume starches gave stabilized Brabender hot-paste viscosity; chickpea had a lower overall viscosity due to its exceptionally long amylose chains.     

Effects of the Barley amo1 and wax Genes on Starch Structure and Physicochemical Properties

Starch structural mutants showing abnormal endosperm characteristics have been used for investigating the effects of the mutation on structure and physicochemical properties of starches. Inbred lines of barley cultivars ‘Shikoku Hadaka 97’ and ‘Glacier AC38’ were used to investigate the impact of amo1 and waxy genes on starch properties. The amo1 type starch had high apparent amylose content and low starch content. The amo1+waxy type starch contained very little amylose. The content of long chains of amylopectin as detected with high‐performance size‐exclusion chromatography (HPSEC) was decreased, and that of amylopectin chains with the degree of polymerization (DP) of 12‐36 was increased in amo1 and amo1+waxy type starches. The amo1 and amo1+waxy type starches exhibited high gelatinization temperatures and low gelatinization enthalpies.     

Physicochemical Properties of Pin Oak (Quercus palustris Muenchh.) Acorn Starch

Physicochemical properties of acorn (Quercus palustris) starch were studied. Acorn starch granules were spherical or ovoid, with diameters ranging from 3–17 μm. Acorn starch exhibited A‐type X‐ray diffraction pattern, an apparent amylose content of 43.4% and absolute amylose content of 31.4%. Relative to other A‐type starches, acorn amylopectin had a comparable weight‐average molar mass (3.9×10⁸ g/mol), gyration radius (288 nm) and density (16.3 g mol⁻¹nm⁻³). Average amylopectin branch chain‐length corresponded to DP 25.5. Onset gelatinization temperature was 65.0°C and peak gelatinization temperature was considerably higher (73.7°C). The enthalpy change of gelatinization was very high compared to non‐mutant starches (20.8 J/g). An amylose‐lipid thermal transition was not observed. Starch retrograded for 7 d at 4°C had very high peak melting temperature (54.2°C) relative to other A‐type starches. Final (260 RVU) and setback (138 RVU) viscosity of an 8% acorn starch paste was high relative to other starches and pasting temperature was 71.5°C.     

Effects of Cationization on Functional Properties of Pea and Corn Starches

Amylography, scanning electron microscopy and storage tests demonstrated that native pea starches were highly resistant to granule disintegration during heating in dilute slurries, resulting in low hot paste viscosity, high retrogradation and syneresis. Cationization at degrees of substitution of 0.02 to 0.05 reduced the pasting and gelatinization temperatures, increased peak viscosities and set-back on cooling but eliminated syneresis after storage at 4°C and − 15°C. The principal effects of cationization were to promote rapid granule dispersion at low pasting temperatures, yielding a molecular dispersion of amylose and amylopectin on heating to 95°C. On cooling, the gel structures were firm and the cationic groups controlled the realignment of starch chains during low temperature storage.     

Structures and Physicochemical Properties of Acid‐Thinned Corn,Potato and Rice Starches

The structures and physicochemical properties of acid‐thinned corn, potato, and rice starches were investigated. Corn, potato, and rice starches were hydrolyzed with 0.14 N hydrochloric acid at 50 °C until reaching a target pasting peak of 200—300 Brabender Units (BU) at 10% solids in the Brabender Visco Amylograph. After acid modification the amylose content decreased slightly and all starches retained their native crystallinity pattern. Acid primarily attacked the amorphous regions within the starch granule and both amylose and amylopectin were hydrolyzed simultaneously by acid. Acid modification decreased the longer chain fraction and increased the shorter chain fraction of corn and rice starches but increased the longer chain fraction and decreased the shorter chain fraction of potato starch, as measured by high‐performance size‐exclusion chromatography. Acid‐thinned potato starches produced much firmer gels than did acid‐thinned corn and rice starches, possibly due to potato starch's relatively higher percentage of long branch chains (degree of polymerization 13—24) in amylopectin. The short‐term development of gel structure by acid‐thinned starches was dependent on amylose content, whereas the long‐term gel strength appeared dependend on the long branch chains in amylopectin.     

Influence of molecular structural characteristics on pasting and thermal properties of acid-methanol-treated rice starches

Rice starches from TKW1, TNG67 and TCS17 varieties, differing widely in amylose contents (0.1, 18.3 and 29.2%) were treated at 45 °C for 1 h in methanol containing various amounts of HCl. The recovery, pasting properties, thermal behaviors, molecular size and chain length distribution of starch were observed. Starches exhibited widely different pasting and thermal behavior upon acid-methanol treated (AMT). Degradation of starches upon AMT affected the leaching extent and chain length of amylose. No obvious changes were found on chain length and content of chain fractions of amylopectin. The pasting viscosity of rice starch decreased with increasing concentration of HCl, and the pasting profiles depended on the variety of rice. The pasting profile of AMT-TNG67 starch showed a two-step increasing pattern during heating, while TKW1 and TCS17 starches showed smoothly increasing pasting curves. The relationship between pasting patterns of AMT-TNG67 starches with amylose leaching and two stages of swelling behavior of starch granules was investigated. Results indicated that the pasting of starch granules depend on the amount, as well as the chain length, of amylose in granules.     

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.     

Morphological,Physicochemical and Structural Characteristics of Oxidized Barley and Corn Starches

Barley starch was oxidized to different levels and the morphological, physicochemical and structural of the resultant oxidized barley starch were determined and compared with oxidized corn starch at the same oxidation level. The amylose content in oxidized starches decreased with increasing oxidation level, and the extent of decrease was similar for both starch types. No evidences of alteration in morphology and X‐ray diffraction pattern were noted after oxidation. The crystallinity of barley starch increased with increasing oxidation but corn starch displayed a reduced crystallinity at 5% NaOCl. The onset and peak gelatinization temperatures of oxidized starches as measured by differential scanning calorimetry showed a slight increase up to 3% NaOCl and then decreased at 5% NaOCl, whereas gelatinization enthalpy gradually decreased with increasing oxidation level. The melting temperature of retrograded oxidized starches increased with increasing oxidation. Both amylose and amylopectin were degraded during oxidation, but a higher degradation in both components as determined by high‐performance size‐exclusion chromatography (HPSEC) was noted for barley starch than for corn starch. Results of amylopectin chain‐length distribution showed that the proportions of A and B1 chains significantly increased while that of B2+ chains significantly decreased. These results suggest that differences in the structure of barley and corn starches affected their responses to oxidation. Barley starch seemed to be more susceptible to oxidation with more significant reduction in pasting temperature, viscosity, and molecular size than corn starch.     

Structural properties and gelatinisation characteristics of potato and cassava starches and mutants thereof

The molecular size of amylopectin (AP) and amylose (AM), AP chain length distribution, crystallinity and granular structure (morphology and granule size distribution) of five wild type potato starches (wtps), five AM free potato starches (amfps), four high-AM potato starches (haps), one wild type cassava starch (wtcs) and one AM free cassava starch (amfcs) were investigated and related to their gelatinisation characteristics. Starches with higher levels of short chains [degree of polymerisation (DP) 6–9 and DP 10–14)] had lower gelatinisation onset (T_o), peak (T_p) and conclusion (T_c) temperatures, whereas higher contents of longer chains (DP 18–25 and DP 25–80) led to higher gelatinisation temperatures. Gelatinisation enthalpies (ΔH) increased with degree of crystallinity. The granules of wtps were larger than those of amfps and haps, respectively. No differences in morphology were observed between wtps and amfps granules, but the haps granules had more irregular surfaces and showed multi-lobed granules.     

Granule‐bound SSIIa Protein Content and its Relationship with Amylopectin Structure and Gelatinization Temperature of Rice Starch

Starch characteristics such as gelatinization properties determine the quality of various products of rice. The eating, cooking and processing qualities of rice are a function of the gelatinization of rice starch. The gelatinization temperature (GT) of rice is controlled by the starch synthase IIa (SSIIa) gene. In the present study, the amount of the starch‐associated SSIIa protein and its relationship with amylopectin structure and GT were investigated. The results indicated that the starch associated SSIIa protein content was positively correlated with GT and level of amylopectin chains with degree of polymerization 12‐24 (DP12‐24), and negatively correlated with the fraction of chains with DP6‐11 and short chain ratio (SCR), i.e. DP6‐11/DP12‐24 (P<0.001). GT was also negatively correlated with DP6‐11 SCR, and positively correlated with DP12‐24. The SSIIa protein content and amylopectin structure showed significant difference between the two SSIIa single nucleotide polymorphisms (SNPs, i.e. guanine‐cytosine/thymine‐thymine (GC/TT)) groups. Rice with GC and TT SNPs had average SSIIa protein contents of 1.076 and 0.681, respectively. Rice with the GC SNPs displayed a lower amount of chains with DP6‐11 and more chains with DP 12‐24 than those with TT SNPs. A mechanism is postulated to explain how SSIIa could determine the distribution of amylopectin side‐chains, which affects the gelatinization temperature of rice starch.