Effects of elevated growth temperature and carbon dioxide levels on some physicochemical properties of wheat starch

Crops of winter wheat (cv. Hereward) were grown in the field under double-skinned polyethylene tunnels in two consecutive seasons (1991–92 and 1992–93). Air containing ambient (350 ppm) or elevated (700 ppm) concentrations of carbon dioxide was circulated through the tunnels, and temperature gradients, typically from 1°C below ambient to 4–7°C above ambient, were maintained within each tunnel. Despite a shorter crop duration and warmer temperatures in the first season, most grain and starch properties showed a similar response to temperature between seasons. Thousand grain weight and grain starch content declined with increase in temperature (from 55±5 mg to 18±2 mg, and from 31±3 mg to 7±2 mg, respectively), the latter reflecting both decreases in granule sizes and fewer amyloplasts per endosperm. Contents of total amylose and lipid-free amylose increased with temperature (from 26±1% to 31±1%, and from 21±1% to 25±1%, respectively), but the contents of lipid-complexed amylose (5·2±1·5%) and lysophospholipids (0·9±0·2%) varied independently of temperature. Starch gelatinisation temperatures ranged from 57·5 to 64·5°C in the first season, and from 58·0 to 61·9°C in the second season, increasing with increase in temperature in both seasons, the data for the two seasons providing almost separate clusters. Gelatinisation enthalpy was constant in the first season (12·6±1 J/g amylopectin) and in the second season (15·5±0·5 J/g amylopectin) with no effect of temperature. The differences in carbon dioxide concentration had no consistent effects on the parameters measured, but small effects were discernible on thousand grain weight, starch content and lipid-free amylose content. There were also effects in certain treatment combinations, specifically at warmer temperatures in the first season and at cooler temperatures in the second season, on thousand grain weight, non-starch solids and lipid-complexed amylose contents.     

糯性普通小麦的产生及其淀粉特性研究

以江苏白火麦（缺失Wx-Dl)和关东107（缺失Wx-Al和Wx-Bl）为亲本配制杂交组合，采用花粉和籽粒剖面染色、蛋白质电泳进行筛选和鉴定，人工创造得到自然界不存在的糯性小麦，并对其直链淀粉含量及淀粉品质性状进行研究。结果表明，所得到的两个糯性小麦吕系直链淀粉含量很低（小于1％），其糊化特性、膨胀势特性亦与普通小麦品种不同；RVA高峰粘度明显低于其亲本，其高峰粘度出现较快，而且反弹值不明显；其淀粉膨胀能力远大于亲本。     

Texture determinants of cooked,parboiled rice. II: Physicochemical properties and leaching behaviour of rice

This paper reports the pasting, gelatinisation and leaching behaviour of 11 cultivars of rice, the starch structural properties of which were determined in the preceding paper. The results show that the contents of leached amylose in the cooking water, as determined by both size exclusion–high performance liquid chromatography (SE–HPLC) and iodine colorimetry, were correlated positively with the texture of cooked rices, which possessed total amylose contents in the range 18·4–29·5%. The amount of leached amylose depended on the total amylose content of the rice. A similar correlation between the conventional «setback» value, measured using the Viscoamylograph, and the texture of cooked rice may be a result of the leached starch content. The gelatinisation temperatures of rice starches determined by differential scanning calorimetry (DSC) were not correlated with the texture of cooked rice, but were significantly related to the crystallinity of the rice starch. The longest chain population (92–98 DP_n), which had been detected previously in the hard rice samples, was not found in their corresponding leached starches. This observation may well support the suggestion in the preceding paper that the longest amylopectin chains could interact with other components in rice, the resultant complexes being retained in the cooked grain and inhibiting softening.     

Physicochemical properties and amylopectin fine structures of A- and B-type granules of waxy and normal soft wheat starch

This work fractionated waxy and normal wheat starches into highly purified A- and B-type granule fractions, which were representative of native granule populations within parent native wheat starches, to accurately assess starch characteristics and properties of the two granule types. Wheat starch A- and B-type granules possessed different morphologies, granule specific surface area measurements, compositions, relative crystallinities, amylopectin branch chain distributions, and physical properties (swelling, gelatinization, and pasting behaviors). Within a genotype, total and apparent amylose contents were greater for A-type granules, while lipid-complexed amylose and phospholipid contents were greater for B-type granules. B-type (relative to A-type) granules within a given genotype possessed a greater abundance of short amylopectin branch chains (DP_n < 13) and a lesser proportion of intermediate (DP_n 13–33) and long (DP_n > 33) branch chains, contributing to their lower relative crystallinities. Variation in amylose and phospholipid characteristics appeared to account for observed differences in swelling, gelatinization, and pasting properties between waxy and normal wheat starch fractions of a common granule type. However, starch granule swelling and gelatinization property differences between A- and B-type granules within a given genotype were most consistently explained by their differential amylopectin chain-length distributions.     

The Effect of Heat–Moisture Treatment on the Structure and Physicochemical Properties of Normal Maize,Waxy Maize,Dull Waxy Maize and Amylomaize V Starches

Normal maize, waxy maize, dull waxy maize and amylomaize V starches were heat treated at 100 °C for 16 h at a moisture content of 30%. The results showed that the X-ray intensities of the major d-spacings of all starches increased on heat–moisture treatment (waxy maize > normal maize > dull waxy maize > amylomaize V). This treatment decreased the apparent amylose content (amylomaize V > normal maize), swelling factor (amylomaize V > waxy maize > dull waxy maize > normal maize), amylose leaching (amylomaize V > normal maize), pasting viscosities (amylomaize V > normal maize), acid hydrolysis (amylomaize V > normal maize > waxy maize > dull waxy maize), enzyme hydrolysis (amylomaize V > normal maize > dull waxy maize > waxy maize) and syneresis (amylomaize V > normal maize > waxy maize ≈ dull waxy maize). The gelatinization transition temperatures of all starches increased on heat–moisture treatment (amylomaize V > normal maize > waxy maize > dull waxy maize). However, the gelatinization temperature range increased only in normal maize and amylomaize V starches (amylomaize V > normal maize), while it remained unchanged in both the waxy starches. The enthalpy of gelatinization remained unchanged on heat–moisture treatment in all starches and the pasting viscosities of the two waxy starches were also unaffected. The foregoing data showed that starch chains within the amorphous and crystalline regions of the granule associate during heat–moisture treatment. However, the extent of this association was of a greater order of magnitude within the amorphous regions. DSC studies have indicated associations involving amylose chains (amylose–amylose and amylose–native starch lipids) resulted in the formation of new crystallites of different stabilities. In contrast, associations involving amylopectin chains (amylopectin–amylopectin) did not lead to crystallite formation.     

施氮量对川西平原酿酒小麦原粮及其酿酒品质的影响

为明确施氮量对酿酒小麦原粮品质和酿酒品质的影响,以绵麦902和中科紫糯麦168（糯性）两个小麦品种为材料,设置6个施氮量（0、45、90、135、180、225 kg·hm^-2）,对小麦产量、原粮品质和酿酒品质进行了分析。结果表明：（1）两供试小麦品种的产量和有效穗数无显著差异;随施氮量增加,两品种的有效穗数、穗粒数及产量增加,均在施氮225 kg·hm^-2达最大值。（2）随施氮量增加,两个小麦品种的籽粒蛋白质、脂肪和灰分含量增加,均在135 kg·hm^-2处理下较高;淀粉含量和粉质率降低,绵麦902直链淀粉含量和直支比均以180 kg·hm^-2处理最高,分别为22.6%和0.641,支链淀粉含量以45 kg·hm^-2处理最高,为 42.6%;中科紫糯麦168直链淀粉含量和直支比均以45 kg·hm^-2处理最高,分别为3.9% 和0.058,支链淀粉含量以90 kg·hm^-2处理最高,为69.3%。（3）与中科紫糯麦168相比,绵麦902出酒率较高,总酸、总酯含量较低,增施氮肥显著降低总酸含量,显著增加总酯含量;施氮90~135 kg·hm^-2范围内两品种出酒率较高,总酸和总酯含量较协调;（4）相关分析表明,出酒率与直链淀粉含量和粉质率呈显著和极显著正相关,与脂肪含量呈极显著负相关;总酸含量与总淀粉、支链淀粉和脂肪含量呈显著正相关,与粉质率呈显著负相关;总酯含量与灰分含量呈显著负相关。本研究认为,绵麦902和中科紫糯麦168酿酒品质各具优势,绵麦902出酒率高,中科紫糯麦168具有更好的产酯特性;在90 ~135 kg·hm^-2施氮范围内,两品种蛋白质含量较适宜,总淀粉和支链淀粉含量较高,灰分含量高,脂肪含量适宜,出酒率和总酸含量也较高,是川西平原酿酒小麦较佳施氮量范围。     

施氮量对糯小麦和非糯小麦籽粒淀粉组分与理化特性的影响

为探明氮肥对小麦籽粒淀粉组分和理化特性的影响,采用田间试验,分析了4个施氮量(0、100、200、300kg·hm~(-2))对糯小麦(农大糯50222)和非糯小麦(轮选987)籽粒淀粉组分与理化特性的影响。结果表明,随施氮量的增加,小麦籽粒淀粉含量降低,轮选987籽粒中B型淀粉粒的数目占比增加,而农大糯50222籽粒的B型淀粉粒数目占比呈减少趋势;增施氮肥能显著提高小麦籽粒淀粉的峰值黏度和谷值黏度。相同施氮量处理下,轮选987淀粉的被测糊化特征参数(除谷值黏度外)均大于农大糯50222。施氮量不同,2个品种籽粒淀粉X-衍射图谱中各峰的位置和相对强度明显不同。随施氮量的增加,轮选987淀粉的相对结晶度增大,而农大糯50222淀粉的相对结晶度减小。相关分析表明,小麦籽粒的直链淀粉含量和直支比与最终黏度、稀澥值、反弹值、糊化温度和峰值时间呈显著正相关,与谷值黏度和相对结晶度呈显著负相关;支链淀粉含量反之。小麦籽粒的B型淀粉粒数目占比与峰值黏度、稀澥值呈显著负相关。综上所述,施氮量可影响小麦籽粒的淀粉含量和粒度分布,进而改变其糊化特性和晶体特征。     

Characterisation of Starch from Inner and Peripheral Parts of Normal and Waxy Barley Kernels

A previous microscopical examination of barley kernels indicated an uneven distribution of amylose in the waxy cultivar SW7142-92, where the subaleurone layer was strongly stained by iodine. To explain these results, starch was isolated from fractions of inner and peripheral parts of kernels of the waxy cultivar and a cultivar with normal starch. Analyses of amylose content showed a higher concentration of amylose in starch from the outer part of the waxy barley kernel, where the amylose, determined by a colorimetric method, made up 8·6% of the starch compared with 5·9% in the middle and 2·2% in the innermost part of the waxy kernel. This difference in amylose distribution was not observed in the normal starch kernel. The results were confirmed by gel permeation chromatography. No differences in amylopectin chain length distribution were detected by size exclusion HPLC and HPAEC-PAD of amylopectins from different parts of the barley kernels.     

糯大麦与非糯大麦种子萌发和胚乳消亡的比较研究

为探明糯大麦与非糯大麦种子萌发和胚乳消亡的差异,以典型糯大麦品种白青稞和甘垦5号以及非糯大麦品种扬农啤10号和苏裸麦1号为材料,采用组织化学染色、树脂半薄切片和光学显微镜观察等方法,研究了糯大麦与非糯大麦胚乳的消亡和淀粉体形态变化。结果表明,在种子萌发过程中,糯大麦种子萌发较好,发芽率较高;糯大麦和非糯大麦颖果胚乳的消亡过程基本相同,呈现出一定的时序性,均是从近胚端的腹部开始消耗,逐渐延伸至背部,最后沿腹沟延伸至远胚端;在大麦种子萌发过程中,近糊粉层中淀粉体最先消亡,小淀粉体早于大淀粉体被消耗;与非糯大麦相比,糯大麦胚乳淀粉体的消亡时间较早、消亡速率较快。概言之,糯大麦与非糯大麦种子萌发过程中胚乳的消亡规律基本相同,但糯大麦种子萌发好,胚乳消亡快。     

Analyses of albumins, globulins and amphiphilic proteins by proteomic approach give new insights on waxy wheat starch metabolism

Starch is composed of two types of glucose polymers: amylose and amylopectin. The Waxy (Wx) locus controls amylose synthesis in the wheat kernel. Hexaploid wheat has three Wx loci located on chromosomes 7A (Wx-A1), 4A (Wx-B1), and 7D (Wx-D1). Eight near isogenic lines (NILs) of Triticum aestivum cv. Tremie with one, two or three Wx null alleles were used. The albumin–globulin fraction, and amphiphilic proteins were separated using 2-dimensional electrophoresis (2DE) allowing the changes in the waxy kernel to be identified. Albumin–globulin fraction showed overexpression of sucrose synthases in the waxy NILs compared to the normal form of Tremie and a decrease in many proteins related to stress and defence metabolism such as serpins. A subunit of ADP-glucose pyrophosphorylase (AGPase), which is known to play a major role in starch synthesis, was also shown to be down regulated in the waxy NILs. Amphiphilic proteins confirmed the observations made on the albumin–globulin fraction with a decrease in a stress-related protein. These different regulations linked to observations made on wheat kernel (thousand kernel weight (TKW), protein amount per grain, size and distribution of the starch granules) led to formulation of the hypothesis that waxy endosperm does not reach maturity of the wild-type endosperm.     

Starch Properties of a Bread Wheat (Triticum aestivum L.) Mutant with an Altered Flour-pasting Profile

Ethyl methanesulphonate treatment of seeds from cultivar Kanto 107 lacking Wx-A1 and Wx-B1 proteins induced a mutant, named K107Afpp4, showing an altered flour-pasting profile, i.ea markedly increased viscosity at a low temperature and a decreased peak time in Rapid Visco Analyser measurement. The colour of the iodine complex of the isolated starch from the mutant remained bluish-purple but its λ_maxdecreased to 584 nm from 601 nm shown by the wild type Kanto 107. The absorbance at 680 nm (blue value) of the mutant starch decreased to 0·206 from 0·324 for Kanto 107. The amylose content of K107Afpp4 starch was 12·7% measured by concanavalin A method, compared to 21·9% for the wild type. The apparent amylose content of the mutant starch measured by amperometric titration was 15·9% while that of Kanto 107 was 25·3%. Gel permeation chromatography showed that the mutant starch has a decreased amount of lower molecular weight fractions than starch from the wild type. Differential scanning calorimetry indicated that mutant starch has a higher gelatinisation peak temperature, 61·8 °C, than the wild type, 59·5 °C. The mutant will be useful as a genetic resource for altering wheat starch/flour properties and for clarifying the relationship between amylose content and wheat quality.     

糯小麦与酿酒谷物黏度特性的比较

为明确糯小麦与其他酿酒谷物糊化特性的差异,为糯小麦在白酒酿造中的应用提供参考依据,比较分析了CD糯麦-2、普通小麦、糯米、高粱和玉米籽粒的淀粉RVA黏度特性。结果表明,不同作物的糊化特性有很大的差异,高梁的峰值黏度最高,糯小麦次之,玉米最低,普通小麦比糯米高,但二者差异较小;到达峰值黏度的时间为5.2~11.2 min,其中糯米糊化最快,糯小麦与糯米接近,比普通小麦快近2 min,普通小麦与高粱相近,玉米最慢;到达峰值黏度的温度为67.2~92.2℃,其中糯小麦和糯米低,分别为70.3℃和67.2℃,普通小麦和高粱分别为84.6℃和83.1℃,玉米则高达92.2℃,糯小麦比普通小麦低约14.3℃。糯小麦配粉能改变谷物的黏度特性,对糊化温度和糊化时间的影响小于对峰值黏度的影响,从不同作物考虑,糯小麦配粉对糯米的黏度特性影响相对较小。结果显示,糯小麦像糯米一样直链淀粉含量极低,其淀粉易糊化,糊化温度低,耗能少;向其他谷物中添加糯小麦可改变其淀粉黏度特性;糯小麦具有代替其他谷物酿造新型风味白酒的潜在优势。     

糯小麦快速选育及糯性亚基纯合速度对选择的响应

为创建糯小麦快速育种程序,进而培育出优质糯小麦新品种,选用4份糯性亲本材料和6份非糯性亲本材料进行杂交,并对分离后代进行早代籽粒碘染、乳熟期田间单株籽粒碘染选择、农艺性状选择、多重PCR分子标记检测和淀粉糊化特性测定。结果显示,糯性亲本作母本或父本,F₀代杂交籽粒均为非糯;大部分杂交组合F₁代自交籽粒中糯性籽粒的出现频率符合1/64的分离比例;非糯性材料作父本的三交组合F₁代自交分离后,糯性籽粒的出现频率符合1/512的分离比例。13个组合中,5个组合的糯粒比例达到100%,7个组合的糯粒比例超过98%,而没有经过籽粒碘染筛选的3个组合的糯粒比例仅为0.79%～6.10%,说明糯性亚基纯合速度对选择可做出快速响应,经过1代籽粒糯性筛选,糯性遗传即可稳定。中选单株均具有糯性小麦典型的RVA图谱,糯小麦面粉的低谷黏度、最终黏度、回生值和峰值时间较非糯小麦面粉显著降低,而峰值黏度、稀懈值和糊化温度在糯小麦和非糯小麦之间差异不显著。对经过2代籽粒糯性筛选的13个杂交组合共410份单株材料进行多重PCR检测,发现全糯质小麦398株...     

Interplay between starch and proteins in waxy wheat

Most of the unique properties of waxy wheat have been associated with the lack of amylose, that in turn may affect the mutual interactions between starch and proteins. To address this particular aspect, we carried out molecular, rheological, and calorimetric studies on flours from two waxy wheat lines that were compared with a non-waxy one. Dough thermal properties and water binding capacity were investigated by Differential Scanning Calorimetry (DSC) and by thermogravimetric analysis, respectively. Protein solvation, aggregation, and thiol accessibility were also investigated, together with dough mixing properties and stickiness. Proteins in waxy wheat samples needed more water to complete solvation, likely because of the water-retaining capacity of waxy wheat starch. In waxy wheat dough, water was tightly bound to starch, and DSC studies indicated an increase in gelatinization temperature. Moreover, the low water mobility in waxy wheat resulted in low and retarded gluten hydration and in high stickiness. In samples with the highest stickiness, protein aggregates were stabilized mainly by hydrophobic interactions. Differences between waxy wheat lines may be attributed to a different structural organization of components within each class of biopolymers.     

Texture determinants in cooked, parboiled rice. I: Rice starch amylose and the fine stucture of amylopectin

The constituent starches from eleven cultivars of non-waxy rice with different degrees of cooking hardness were subjected to detailed analysis. No significant differences were observed in the granule morphology, crystallinity and size distribution of the starch granules that could be correlated with the textures of the cooked, parboiled rices. Differences in the contents of amylose and the fine structures of amylopectin were detected, however, which did correlate with texture. It appeared that the texture of the rices was critically controlled by the proportion of the longest (DP 92–98) and shortest (DP&lE25) amylopectin chains but not the intermediate (DP 43–68) chains. Hard cooking rice tended to have a higher amylose content (or amylose:amylopectin ratio) and more longer chain amylopectin than soft cooking rice, which feature is thought to encourage more extensive intra and/or inter molecular interactions with other components in rice grain, such as protein, lipid and non-starch polysaccharides and results in a firmer texture. The different amylopectin structures may explain why rices that possess similar amylose contents can have different textural properties. Such a correlation suggests that the structure of the starches determined from the SE–HPLC profile of the debranched amylopectin could be useful as a sensitive screening method in the classification of cooked rice texture.     

Impact of pre-germination on amylopectin molecular structures,crystallinity, and thermal properties of pre-germinated brown rice starches

Ungerminated brown rice (UGBR) and pre-germinated brown rice (PGBR) obtained from different pre-germination durations were studied to investigate the changes in total starch contents of flour, amylopectin molecular structures, crystallinity, and thermal properties of starches as affected by pre-germination. Each paddy of three rice cultivars with different amylose contents (RD6, waxy; KDML105, low amylose; and RD31, high amylose) was soaked in water at 30°C for 12 h and incubated over different periods until the three stages of embryonic growth length (EGL) were achieved. The total starch contents of three-stage PGBR flour from all rice cultivars decreased when pre-germination durations were increased. The three-stage PGBR starches from the three rice cultivars had lower weight-average molecular weight (Mw) and number-average molecular weight (Mn) than UGBR starches. All starches from the three rice cultivars displayed an A-type X-ray diffraction pattern (XRD). Isolated UGBR starch from RD6 had the highest (31.33%) relative crystallinity (RC), while RD31 showed the lowest RC (26.79%). The slight increases in the RC of three-stage PGBR starches from three rice cultivars were found after pre-germination. Isolated PGBR starches from the three rice cultivars had higher gelatinization temperatures and enthalpy, but lower retrogradation enthalpy and %retrogradation than UGBR starches.     

小麦籽粒淀粉合成动态及糊化特性的基因型差异

为了明确不同基因型小麦品种籽粒灌浆过程中的淀粉合成动态,为小麦的高产优质栽培提供参考信息,对6个不同基因型小麦籽粒形成过程中淀粉组分的变化及淀粉糊化特性进行了分析。结果表明,非糯性小麦的直链淀粉含量随着花后天数的增加呈上升的趋势,糯性小麦则呈先上升后下降的趋势,所有品种的支链淀粉含量均呈上升的趋势;不同基因型小麦直链、支链淀粉积累速率均呈单峰曲线图,不同品种直链淀粉最大积累速率出现的时间不同,而支链淀粉最大积累速率出现的时间均在花后21d;不同小麦品种的峰值粘度、低谷粘度、最终粘度均随着花后天数的增加而上升;不同品种淀粉糊化特性不同:糯性小麦之间在糊化时间、反弹值上无差异,而在峰值粘度、低谷粘度、最终粘度、稀懈值上的差异达显著水平;对于非糯性小麦,豫麦50和其他品种的多数糊化参数差异达显著水平;糯小麦和非糯小麦在糊化参数上的差异达1%显著水平。     

Swelling and Enzymatic Hydrolysis of Starch in Low Water Systems

The matrix effects of starch to water ratio, temperature and time on the gelatinisation, swelling and enzymatic (alpha -amylase) hydrolysis of five starches (waxy maize, maize, wheat, tapioca and potato) were investigated. It was established that by controlling the extent of gelatinisation with appropriate incubation conditions, some residual order could be retained. With starch to water ratios of 1:1, the amount of residual order represented 67·5, 40·9, 37·7, 30·3 and 15·1 for waxy maize, maize, wheat, tapioca and potato starches respectively. Whilst gelatinisation was controlled by the availability of water together with temperature and time, the effect on swelling was more marked. This reflects the fact that although granule order may be (just) lost under limiting (water) conditions, the expansion of amorphous material is more extensively moderated when water is restricted. Under the conditions investigated, the amount of hydrolysis exceeded the swelling factor which shows that although the granules may be only partially swollen, they are susceptible to amylase hydrolysis and hence potentially digestion. However, the amount of hydrolysis is also intimately related to the extent of gelatinisation which has important implications to food, alcohol production and other industrial processes.     

Retrogradation and Gel Textural Attributes of Corn Starch Amylose and Amylopectin Fractions

An understanding of relationships between starch molecular structure and function could increase the opportunity to develop additional uses for starch. Using a combined aqueous (aq.) leaching and alcohol precipitation technique, six amylose fractions were obtained from regular and two high amylose (hAM) corn starches (50 and 70%). Five amylopectin fractions were obtained from regular and waxy corn starches. After freeze-drying the fractions, high performance size exclusion chromatography (HPSEC) was used to estimate weight-average (M_w) and number-average (M_n) molecular weights, and to determine polydispersity (M_w/M_n) and purity. Increase in fraction reducing power after pullulanase treatment was determined and expressed as a relative index of branching. Amylose-fractions showed varying but similar (P>0·05) M_w(1·40–5·68E+05), similar polydispersities (2·1–2·9), and branching values (1·93E-04–4·14E-05). Amylose branching increased with decreasing M_w. Amylopectin had varying M_w(2·88–5·43E+07) and similar polydispersities (1·3–1·5), but different branching values (7·30E-04–1·54E-03), that did not follow any M_worder. Fraction melting temperatures, enthalpies, and gel retrogradation behaviours were determined using differential scanning calorimetry (DSC). No enthalpies were observed for amylose fractions. Amylopectin fractions with high branching values that had intermediate to low M_w(3·75–2·88E+07), showed marked retrogradation. Enthalpy was correlated neither to branching nor M_w. Gel textural profile analysis (fracturability, adhesive force, cohesiveness, and springiness) showed that for amylose, intermediate M_wfractions promoted less fracturability, while adhesive force, and stringiness increased with a decrease in M_w. For amylopectin, the intermediate M_wand highly branched fractions reduced fracturability, and promoted adhesive force, and stringiness. Amylopectin fractions of intermediate M_wand high extent of branching underwent increased retrogradation. Amylose gel textural attributes were governed by molecular weight, while molecular weight and branching governed amylopectin gel textural properties.