Paste viscosity of rice starches of different amylose content and carboxymethylcellulose formed by dry heating and the physical properties of their films

Starch modified by combination with sodium carboxymethylcellulose (CMC) has been reported to have improved film properties. In this study, rice starches with different amylose content were heat-treated in a dry state after being impregnated with low or medium-viscosity CMC. Noticeable change was found in pasting properties of the starches after dry heat treatment with CMC. It indicated that crosslinkage occurred between the starch and CMC. The waxy starch showed significant change in viscosity throughout pasting after dry heating with CMC, suggesting that the ester bonds were mostly formed between the hydroxyl groups in amylopectin branches of rice starch and carboxylate acid groups of CMC. Particle size also increased after heat treatment with CMC. The modified starch-based films showed improvement in the tensile strength. Both water vapor and oxygen permeability reduced for the modified starch-based films. Dynamic mechanical analysis (DMA) study showed that the values of G′ of modified starch-based film were higher than those of native starch-based film over the temperature range −40 to 60 °C. The heating process with CMC could be used as a modification method for starch and provide desirable properties of starch-based films.     

Rheology and functional properties of starches isolated from five improved rice varieties from West Africa

Starches were isolated from five improved rice varieties developed by West African Rice Development Agency (WARDA) namely FARO 32, FARO 51, FARO 52, FARO 54 and NERICA. Starch yield and amylose content varied between 73.77–70.02% and 22.88–24.48% respectively. Starches were polyhedral in appearances and within the size range 1.5–6.1 μm. The X-ray diffraction patterns of the starches show a peak centered on 2θ = 15.1°, a doublet on 17.1° and 18.1°, and another single peak at 23.12°. However, NERICA shows no doublet but a single peak at 2θ = 17.1° with a small shoulder. The peak viscosity of the starches ranged between 147.48 and 209.17 RVA corresponding to FARO 52 and NERICA respectively. A neat distinction is observed between the marked shear thinning of FARO 52 and the apparently plastic behavior of the other samples. Important differences appear in the low shear region where the viscosity increases in the following order: FARO 52 < FARO 54 < FARO 51 < FARO 32 < NERICA. The mechanical spectra exhibit similar profiles as the storage modulus (G′) prevails over the viscous component (G″) and is weakly dependent on the frequency. However, the storage modulus increases in the same order observed for low shear viscosity. The percentage retrogradation was between 61.9 and 86.6% and NERICA starch showed the least retrogradation indication. NERICA starch exhibited highest swelling and solubility, while the least was observed in FARO 52. Rheology and functional properties are dependent of amylose composition. This study provides knowledge for the utilization of starches isolated from improved rice varieties that would be relevant for both domestic and industrial applications.     

Effects of annealing on the physicochemical properties and enzymatic susceptibility of rice starches with different amylose contents

This study investigated the effects of annealing (ANN) on the properties of rice starches with high, medium and low-amylose contents. The starches were heated with excess water at 45 °C, 50 °C and 55 °C for 16 h. The swelling power, solubility, pasting properties, enzymatic susceptibility, morphology and X-ray crystallinity of the starches were evaluated. Annealing reduced the swelling power and solubility of the starches. ANN at 55 °C increased the pasting temperature and decreased the peak viscosity of the high-amylose rice starch. However, annealing decreased the peak viscosity of the low-amylose starch. The annealed rice starches presented a lower final viscosity and setback than did the native starches, with the exception of the low-amylose starch, which showed an increase in setback. Annealing increased the starches’ susceptibilities to α-amylase and promoted a reduction in their relative crystallinity.     

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.     

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.     

两种大米淀粉及其磷酸酯淀粉理化特性的比较研究

对比分析2种大米(籼米和粳米)的全粉、淀粉和取代度均为0.068的磷酸酯淀粉的理化特性.粳米的全粉、淀粉和磷酸酯淀粉的膨胀力分别为7.5,10.7,21.6 g/g,分别高于籼米的全粉、淀粉和磷酸酯淀粉的膨胀力(5.8,8.9,17.4 g/g).2种大米淀粉经磷酸酯化后透光率增高,相应淀粉的透光率次之,全粉的透光率最低,籼米的全粉、淀粉和磷酸酯淀粉的透光率分别低于粳米的全粉、淀粉和磷酸酯淀粉的透光率.经快速黏度分析仪测定的糊化特性结果表明,淀粉或变性淀粉膨胀力高,其峰值黏度和崩解值也高,此外,蛋白质含量和直链淀粉含量也极大的影响了淀粉的糊化特性.使用动态流变仪测定的流变特性表明,在相同的温度下,籼米的全粉、淀粉和变性淀粉的储能模量(G')分别比粳米的全粉、淀粉和变性淀粉的储能模量(G')高,对于相同的大米品种,全粉的储能模量(G')最高,变性淀粉的储能模量(G')最低.     

Properties of starches separated from potatoes stored under different conditions

Starches from 11 potato cultivars stored at five temperatures (4, 8, 12, 16 and 20 °C) for 120 days were evaluated for physicochemical, thermal and pasting properties. Amylose content and swelling power increased with increase in storage temperatures. The proportion of small size granules was higher in starches from potatoes stored at 4 °C. The starch granules of stored potatoes were slightly rough-surfaced and pitted; the effect was pronounced in those stored at 4 °C. Starches from potatoes stored at 4 °C showed lower onset gelatinization temperature and conclusion temperature than did starches from potatoes stored between 8 and 20 °C. Starches from potatoes stored at higher temperature (20 °C) showed higher peak viscosity, set back, as well as gel hardness, chewiness and gumminess than did starches from those stored between 4 and 16 °C. Amylose content showed significant positive correlation with gumminess and setback while swelling power showed significant positive correlation with peak viscosity and hot-paste viscosity.     

不同品种小麦淀粉提取及糊化粘度性质比较

采用实验室方法提取30种不同小麦籽粒淀粉;并用快速粘度分析仪(RVA)测定不同品种小麦淀粉糊化粘度性质,分析各粘度性质相关性及差异性。结果表明:普通小麦淀粉糊化粘度性质参数明显不同,粘度性质参数差异性显著,各参数间相关性极显著。     

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.     

Improving gel formation of rice starch added with cross‐linked resistant starch prepared from rice starch

The gel formation properties of non‐waxy rice starch with cross‐linked resistant starch with phosphate (RS4, 10, 20, and 30% based on rice starch) prepared from three rice varieties with different amylose (AM) content were investigated to increase dietary fiber content, improve gel structure, and reduce the glycemic index of rice products. The AM contents of rice starches were 1.71% in Hanganchal1, 22.47% in Nampyeong, and 33.39% in Goamy. All RS4 showed A‐type crystallinity and their RS levels were 46.91, 54.54, and 66.01%, respectively. The initial pasting temperatures of RS4 added rice starches increased as RS4 contents increased, but peak and breakdown viscosities and enthalpy change (△H) reduced. The RS4 addition improved gel shape and texture properties including hardness, cohesiveness, and gumminess, except the 30% Goamy RS4 added gel. The 20% RS4 addition was appropriate to form rice starch gels. The network structure of RS4 added gel formed more regular and firmer than that of control, because RS4 granules were entrapped within the gel matrix like observed by light microscope and scanning electron microscopy. It is suggested that RS4 not only assist in forming a rigid network structure but also increasing a dietary fiber content.

     

A novel size-exclusion high performance liquid chromatography (SE-HPLC) method for measuring degree of amylose retrogradation in rice starch

The objective of this study was to develop a new method to measure the degree of amylose retrogradation in rice starch using size-exclusion high performance liquid chromatography (SE-HPLC). This developed method is based on the change in molecule size related to the retention time of amylose. Results showed that SE-HPLC was able to provide accurate data to evaluate the amylose retrogradation by comparing with other well-established methods. The principle of the measurement was further studied in molecular level by molecular dynamic (MD) simulation. It indicated that amylose molecules were transformed from disordering configuration to ordering one due to the increase in Van der Waals (Vdw) and hydrogen forces, and decrease in bonded interaction during the short-term storage.     

Isolation,composition, morphological and pasting properties of starches from rice cultivars grown in Nigeria

The isolation, composition, morphology and pasting properties of rice starches from different rice cultivars (N2R, Nerica II rice; IGR, Igbemo rice; ILR, Ilaje rice; and EAR, Efon Alaye rice) were studied. The starches were isolated from their flours by using a modified deproteination method in 0.1% NaOH. The highest starch yield of 65% was obtained from EAR with a residual protein of 0.41% and lowest starch yield of 45.70% from IGR with a residual protein of 0.42%. The AAM concentration of rice starches ranged from 21.88 to 26.04%. The sizes of the starch granules obtained from SEM were between 3 and 8 µm, some of the granules were individual (single) while others were fused (compound granules). The starch granules were small, polygonal and irregular in shape. The pasting parameters were evaluated using rapid visco analyser (RVA). Significant differences were observed in individual pasting parameters such as peak viscosity (PV), breakdown viscosity (BV), final viscosity (FV) and setback viscosity (SV). Cooked ILR starch had the highest PV (279.69 RVU; rapid viscosity units) and BV (52.50 RVU) when compared to the other starches. In contrast, N2R showed the highest FV (329.92 RVU) and SV (102.50 RVU), the latter due to the high concentration of AAM. The results revealed that cultivar has an effect on composition and pasting properties of rice starch.     

Characterisation of starch quality from barley varieties grown in South Africa

Starch is a major determinant of grain quality in cereals but the variation in starch structure has yet to be fully explored in its relation to processing impacts. This study examined the starch properties of South African grown malting barley varieties. Starch amounts, amylose content, covalently bound phosphate, starch granule size, starch molecular structure and pasting properties were examined. There was no difference in amylose content but there was variation in the amylose chain length distribution, despite all barleys showing similar granule parameters. The longer amylose chain length resulted in increased pasting temperature. There was no difference in phosphate content for these samples. Starch properties for the brewing industry are important in the context of the production of fermentable sugars. The variation in starch structure was not observed when measuring content and could impact on fermentation efficiency through variation in fermentable sugars hydrolysed from the starch.     

In vitro measurement of resistant starch of cooked milled rice and physico-chemical characteristics affecting its formation

Resistant starch (RS) content was determined in 10 indica and japonica milled rices with different levels of amylose. The effect of microbial growth during starch digestion on the measurement of RS, and the correlation between physico-chemical characteristics and RS contents of milled rice were analysed. Results indicated a significant decrease (P < 0.01) in assay values of RS after antibiotics addition, and the markedly decreased sample pH due to fermentation might be the main reason for errors in RS determination. Correlation analyses showed that RS contents of milled rice were closely related to amylose content (r = 0.75, P < 0.05) and protein content (r = 0.78, P < 0.01). No significant correlation existed between RS content and some relatively simple physical properties, such as width, shape and elongation ratio of rice grain, which were reported to be good indictors of rate of rice starch digestion, while a significant positive correlation was found between elongation ratio and digestible starch in cooked milled rice (r = 0.67, P < 0.05).     

不同直链淀粉含量大米淀粉性质的研究

以4种不同直链淀粉含量的米淀粉为原料,采用扫描电镜（SEM）、全波长自动扫描仪,质构仪等对其颗粒形貌、淀粉-碘复合物性质、ATP指标及透明度性质进行观察研究。结果表明,不同直链淀粉含量的大米淀粉颗粒形貌差异不大,均呈现不规则多边形,表面不光滑;随着直链淀粉含量的增加,淀粉颗粒的平均链长和聚合度不断增大,优糯3号淀粉颗粒内部短链数量较多,随着直链淀粉含量的增加淀粉颗粒内部的长短链比率逐渐趋近于1;淀粉糊的质构性质测定显示出淀粉糊的硬度、胶着性和咀嚼性随着直链淀粉含量的增加呈现出明显的上升趋势,弹性随着直链淀粉含量的增加变化不大,而凝胶的粘聚性明显下降;糊透明度随直链淀粉含量的增大而不断降低。      

Some characteristics of acetylated, cross-linked and dual modified Indian rice starches

Starches from broken rice grains derived from three varieties (PUSA-44, PR-106, and PR-114) were modified by hydroxypropylation with propylene oxide and esterification with adipic acid anhydride and/or vinyl acetate. Degree of substitution and acetyl contents (in parentheses) was relatively low; ranges between 0.02 (0.53%) and 0.12 (3.09%) for hydroxy-propylated cross-linked and acetylated starch samples. The acetylation and dual modification of starches increased the paste clarity, solubility, swelling power, sediment volume, and gel strength but decreased the gel elasticity in all the three varieties. However, the adhesiveness increased only upon dual modification in PUSA-44 and decreased in other two varieties. Cross-linking reduced the solubility, swelling power, sediment volume, and gel elasticity while increased the paste clarity, gel strength and adhesiveness. The physico-chemical characteristics of relatively high amylose variety PUSA-44 among three varieties were significantly lower than those from varieties with low amylose content whereas PUSA-44 had shown improved gel properties as compared to other two varieties.     

Physiochemical,Pasting, and Thermal Properties of Starch Isolated from Different Barley Cultivars

Starches from eight different barley cultivars were isolated and evaluated for their physiochemical, thermal, and pasting properties. The amylose content varied significantly among cultivars and ranged from 21.0 to 28.3%. The majority of the starch granules were of the B-type (20 to 40 μm) in size and accounted for 50.5 to 61.6% of the total granules. The starch gel from RD-2052 showed the highest firmness (0.55 N). The pasting behavior of starch varied significantly; the PL-172 cultivar showed the highest peak viscosity (2622 cP) while it was lowest for RD-2035 (1913cP). The time to peak of pasting properties exhibited a significant (p ≤ 0.05) negative correlation with water solubility index (r =??0.74). The pasting temperature showed a significant (p ≤ 0.05) positive correlation with water binding capacity (r = 0.73) and significant negative correlation with water solubility index (r =??0.82). The highest enthalpy of gelatinization (ΔH) was exhibited by DWR-28 cultivar (4.9 J/g). Amylose content showed a significant (p ≤ 0.01) negative correlation with ΔH (r =??0.90). A significant (p ≤ 0.01) positive correlation was observed between gelatinization temperature range and water binding capacity of starch (r = 0.85).     

Multi‐scale structural and digestion properties of wheat starches with different amylose contents

The physicochemical and digestion properties of three wheat starches with different amylose contents were studied. Scanning electron microscopy (SEM) showed they displayed a spherical disc‐like form, a lenticular shape and an irregular morphology, respectively. Compared with waxy and normal wheat starches, high‐amylose wheat starch (HAWS) was characterised by the presence of lower molecular weight amylose fraction, and its granules demonstrated the highest resistance to the cooking. The changes in the IR ratio 1022/999–1047/1022 cm^?1 following the gel storage suggested the molecules of HAWS are more readily to re‐associate and re‐organise into a more organised status than other two starches. The determination of glucose release showed that HAWS had the lowest digestion kinetics (P < 0.001), and this difference in the digestion properties between HAWS and the other two starches might imply that starch molecular structure, in particular amylose structure is another key factor for manipulating starch digestion property rather than amylose content alone.     

Relationship between physicochemical and rheological properties of starches from Indian wheat lines

Starches from nine Indian wheat lines were evaluated to study the relationships between physicochemical and rheological properties. Large granules (>15 μm) were present in the highest proportion followed by medium (5–15 μm) and small granules (<5 μm). Amylose content ranged between 27.4 and 37.2%. Starch with the highest proportion of large granules (68.9%) showed higher values of G′_peak (576 Pa) and G′_final (432 Pa). Amylose content showed positive relationships with retrogradation, gel firmness, gumminess and adhesiveness while negative with springiness. Cooked starch pastes with the highest amylose content (37.2%) had higher ΔH_ret (0.88 J g^?1), G′_ret (361 Pa), adhesiveness (1.48 Ns), firmness (0.45 N) gumminess (0.22 N) and the lowest springiness (0.88). Amylose–lipid complex (AML) dissociation showed negative relations with swelling power, G′_peak, G′_breakdown and breakdown viscosity (r = ?0.779, ?0.66, ?0.771 & ?0.775, respectively, P < 0.05) while positive relationship with pasting temperature (r = 0.775, P < 0.05).