Differences In Amylose Content Research Articles

Effect of composition on the structure and digestibility of starch in Idli batter

AbstractThis study investigates the effects of varying the proportion of parboiled rice, raw rice, mixed rice, and black gram on idli batter structure and starch digestibility. A total of six different batters (batters 1 to 6) were prepared by varying the composition of raw material. Batter 1 (Parboiled Rice: Black gram dal: Baking soda), Batter 2 (Parboiled Rice: Black gram dal: Yeast), Batter 3 (Parboiled Rice: Raw Rice: Mixed Rice: Black gram dal), Batter 4 (Raw Rice: Mixed Rice: Black gram dal), Batter 5 (Raw rice: Yeast) and Batter 6 (Parboiled Rice: Black gram dal). In comparison to the other five batters, batter 6 (parboiled rice (3): Black gram dal (1)) exhibited superior texture, sensory, enzyme activity, and better digestibility. Structure changes in starch for batter 6 were noticeable until day five and complete degradation was observed after day seven, whereas in other batters, the structure degraded from 3rd day of storage. Batter 6 exhibited the highest protein content (0.6 mg/g to 0.3 mg/g) and lowest reducing sugar content (4.51 mg/g to 6.66 mg/g) from day 1 to day 7 of the storage period. The difference in amylose content from day 1 to day 7 (27.80% to 26.75%) was low compared to others. The starch digestibility index of batter 6 was 40.35% on day 1 and 68.96% on day 7 which was comparatively less compared to other prepared batters. As a result, the proportion of dal and parboiled rice used in batter preparation significantly influences its storage, digestibility, and enzyme activity. Thus, studying the method and proportion of idli preparation helps us understand how the batter is stored, digested, and modified, thereby improving our understanding of Indian cuisine.

Expression Characteristics and Sequence Variation Analysis of Rice Starch Regulator 1 Gene in Japonica Rice With Transgressive Variation

The parents and transgressive variation lines of hybrids with significant difference in amylose content were selected to compare and analyze the accumulation characteristics of amylose and the change of OsRSR1 expression in grains in the process of grain filling, and the PCR technology was used to clone the OsRSR1 gene base sequence of four varieties. The results showed that the amylose content in grains increased gradually with grain filling process, the amylose content of offspring and parents with high amylose content were higher than the offspring and parents with low amylose content, hybrids could obtain the transgressive variation lines through the continuous directional selection of amylose content in grain, and the accumulation of amylose content in grain was closely related to genotypes. The expression quantity of OsRSR1 gene in grain was increasing during the grain filling process, the amylose content of grain was closely related to the activity of OsRSR1 gene, and the expression of grain OsRSR1 gene could also produce transgressive variation.

Organic Pea Starches – I. Comprehensive Investigation of Morphological and Molecular Properties

AbstractThe comparatively high amylose (AM) content in native pea starch leads to a good functionality in food and non‐food products. Nevertheless, it has also been reported that pea starch tends to cause manufacturing problems more often than other starches. It has been suggested that this is due to substantial variation of the starch qualities originating from different pea starch varieties. Therefore, additional research which explores morphological, physicochemical, molecular, and techno‐/functional properties of starches from multiple pea varieties is necessary. Here, a large variety of pea starches are analyzed. The structure and size of the starch granules is studied using scanning electron microscopy (SEM), laser particle sizing (LPS), and image analysis of optical microscopy (IAOM). The morphological appearance and size do not differ significantly between the pea cultivars. The AM content is determined with two methods, both based on iodine interaction with the AM helix. The method suggested here (SEC‐prep) results in systematically higher AM content. This is due to better solubilization of the starch. Nevertheless, only small differences between the pea cultivars are observed. No differences in morphological appearance, particle size, and only minor differences in AM content, significant variations in the molar mass distribution of the total starch fraction (MwST) and of the AM fraction (MwAM) are found.

Effect of Germination on Improving Grain Quality, Chemical Composition, Antioxidants, and Phytic Acid in Rice (Oryza sativa)

This study aimed to study the effect of the germination process on grain quality, chemical composition for brown rice and comparing them with white rice for use it is on a commercial scale . Three rice varieties namely Sakha 104(Japonica), Giza 178(Japonica- Indica), and Giza 182(Indica) were used in this study. And the three statuses (milled rice, brown rice, and germinated brown rice). A completely randomized design in the factorial arrangement was used in this experiment to determine some cooking and eating quality characters i.e. gelatinization temperature, amylose content and elongation %, Water uptake, hardness, chemical composition: Phytic acid, total antioxidant capacity, and panel test evaluation for rice samples. The results indicated that there were significant differences in amylose content and gelatinization temperature among the three rice statuses and no significant difference in these characters with the three rice varieties under study. Germinated brown rice showed the lowest amylose content (15.58%), followed by brown rice (17.26%) and white rice (18.39%). Brown rice gave the highest temperature followed by germinated brown rice then milled rice. A maximum elongation ratio was observed in Giza178 (Japonica Indica). White rice gave the maximum elongation (47.18%) followed by germinated brown (24.56 %) then brown rice (16.08 %). Japonica rice exhibited lower hardness than indica rice. The strongest value (4.82) was recorded at brown rice, while the weakest value (3.64) was in white rice. The Indica rice variety Giza181 had the highest protein and fat%. The germinated brown rice had the highest value of protein, crude fiber, and fat (7.27, 1.98, and 2.87%, respectively), compared with compared to brown rice and white rice. White rice had lower Phytic acid (%) followed by germinated brown rice, then brown rice. Japonica rice cultivar (Sakha 104) has a higher antioxidant level than Indica rice cultivar (Giza 182)....

Waxy Gene-Orthologs in Wheat × Thinopyrum Amphidiploids

Starch, as the main component of grain in cereals, serves as the major source of calories in staple food and as a raw material for industry. As the technological and digestive properties of starch depend on its content, the management of its components, amylose and amylopectin, is of great importance. The starch properties of wheat grain can be attuned using allelic variations of genes, including granule-bound starch synthase I (GBSS I), or Wx. The tertiary gene pool, including wheatgrass (Thinopyrum) species, provides a wide spectrum of genes-orthologs that can be used to increase the allelic diversity of wheat genes by wide hybridization. Octaploid partial wheat–wheatgrass hybrids (amphidiploids, WWGHs) combine the complete genome of bread wheat (BBAADD), and a mixed genome from the chromosomes of intermediate wheatgrass (Thinopyrum intermedium, genomic composition JrJrJvsJvsStSt) and tall wheatgrass (Th. ponticum, JJJJJJJsJsJsJs). Thus, WWGHs may carry Wx genes not only of wheat (Wx-B1, Wx-A1 and Wx-D1) but also of wheatgrass origin. We aimed to assess the level of amylose in starch and investigate the polymorphism of Wx genes in 12 accessions of WWGHs. Additionally, we characterized orthologous Wx genes in the genomes of wild wheat-related species involved in the development of the studied WWGHs, Th. intermedium and Th. ponticum, as well as in the putative donors of their subgenomes, bessarabian wheatgrass (Th. bessarabicum, JbJb) and bluebunch wheatgrass (Pseudoroegneria stipifolia, St1St1St2St2). Although no significant differences in amylose content were found between different WWGH accessions, SDS-PAGE demonstrated that at least two WWGHs have an additional band. We sequenced the Wx gene-orthologs in Th. bessarabicum, P. stipifolia, Th. intermedium and Th. ponticum, and developed a WXTH marker that can discriminate the Thinopyrum Wx gene in the wheat background, and localized it to the 7E chromosome in Th. elongatum. Using the WXTH marker we revealed the allelic polymorphism of the Thinopyrum Wx gene in the studied WWGHs. The applicability of Thinopyrum Wx genes in wheat breeding and their effect on starch quality are discussed.

Comparative analysis on grain quality and yield of different panicle weight indica-japonica hybrid rice (Oryza sativa L.) cultivars

Indica-japonica hybrid rice (Oryza sativa L.) cultivars showed high yield potential and poor tasting quality when compared with common japonica rice cultivars. Large panicle is a prominent factor of high yield for indica-japonica hybrid rice cultivars, and the panicle weight varies greatly among different indica-japonica hybrid rice cultivars. It is important to research on yield and grain quality of different panicle weight indica-japonica hybrid rice cultivars. In this study, two different panicle types indica-japonica hybrid cultivars were used to research on the relation of yield and grain quality. The yields of two heavy panicle weights indica-japonica hybrid cultivars were significantly higher than that of two medium panicle weight rice cultivars. The cooking and eating quality and starch properties of different panicle type cultivars were evaluated. Yongyou 6715 (medium panicle) and Yongyou 1852 (heavy panicle) got the relatively higher cooking and eating quality. Rice cultivars with medium panicle weight had more large starch granules and higher relative crystallinity than cultivars with heavy panicle weight. Transition temperature and retrogradation enthalpy (ΔHret) of medium panicle type cultivars were significantly higher than that of heavy panicle type cultivars. There was no significant difference in amylose content among different panicle type cultivars. Protein content of heavy panicle type cultivar was higher than that of medium panicle type cultivar, and protein content is the main factor affect cooking and eating quality in this study. The cultivar Yongyou 6715 got the highest taste value with the lowest protein content. Thus, it is suggested that the emphasis on improving rice cooking and eating quality of indica-japonica hybrid rice cultivars is how to reduce the protein content in rice grain. According to the results of this study, medium panicle type with high grain weight is the desired panicle type for high quality indica-japonica hybrid rice breeding.

Understanding the mechanism of ultrasonication regulated the digestibility properties of retrograded starch following vacuum freeze drying

The digestibility properties and structural changes of retrograded starch (RS3) induced by ultrasonic treatment (UT) were investigated. The digestion profiles showed that UT increased the slowly digestible starch (SDS) or resistant starch (RS) of RS3 as an effective green process, corresponding to a change in hydrolysis kinetic parameters (equilibrium starch hydrolysis percentage and kinetic constant). SEM analysis showed that ultrasound led to breakage of RS3 particles followed by cracking, reorientation and crystallization. Differences in amylose content, granule size, and ζ-potential were found for native RS3 and ultrasound-treated RS3 (UT-RS3). UT decreased the relative crystallinity and gelatinization enthalpy but enhanced short-range order of RS3 based on the results of XRD, DSC, and FT-IR, respectively. Surprisingly, diffractive peaks at 13°and 20° (V-type crystalline structure) and a new exothermic peak were also observed for UT-RS3. The outcome was believed to open new pathways for regulating the digestibility properties of RS3 by UT and development of low glycemic response food.

Characterisation of starch quality from barley varieties grown in South Africa

SummaryStarch 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.

Physicochemical properties of potato starches manufactured in Hokkaido factories.

Potato starch is an important agricultural product in Hokkaido, the northernmost island of Japan, with output of around 0.18 million tons/year. The present investigation was conducted to evaluate the physicochemical properties of potato starch samples manufactured in 10 factories in Hokkaido. The starch samples were analyzed for pasting properties by rapid visco analyzer (RVA), gelatinization properties by differential scanning calorimetry (DSC), color components, and minerals, amylose, and resistant starch (RS) contents. The phosphorus and potassium contents of potato starches averaged 746ppm and 681ppm, ranging from 669 to 835ppm and from 481 to 803ppm, respectively. Relatively wide ranges were noted in the contents of sodium (35-134ppm), magnesium (50-121ppm), and calcium (34-164ppm). RVA analysis revealed clear differences in peak viscosity (PV) and breakdown (BD) among starch samples examined. Higher contents of divalent cations, magnesium, and calcium, were associated with lower values of PV and BD, whereas the phosphorus content did not affect PV and BD. The differences in amylose content, DSC gelatinization properties and color components as well as RS content in raw starch were not large.

Molecular Structure and Physicochemical Properties of Starches from Rice with Different Amylose Contents Resulting from Modification of OsGBSSI Activity.

OsGBSSI, encoded by the Waxy (Wx) gene, is the key enzyme in the synthesis of amylose chains. Transgenic rice lines with various GBSSI activities were previously developed via site-directed mutagenesis of the Wx gene in the glutinous cultivar Guanglingxiangnuo (GLXN). In this study, grain morphology, molecular structure, and physicochemical properties were investigated in four transgenic lines with modified OsGBSSI activity and differences in amylose content. A milky opaque appearance was observed in low- and non-amylose rice grains due to air spaces in the starch granules. Gel permeation chromatography (GPC) and high-performance anion-exchange chromatography (HPAEC) analyses showed that although OsGBSSI can synthesize intermediate and extra-long amylopectin chains, it is mainly responsible for the longer amylose chains. Amylose content was positively correlated with trough viscosity, final viscosity, setback viscosity, pasting time, pasting temperature, and gelatinization temperature and negatively with gel consistency, breakdown viscosity, gelatinization enthalpy, and crystallinity. Overall, the findings suggest that OsGBSSI may be also involved in amylopectin biosynthesis, in turn affecting grain appearance, thermal and pasting properties, and the crystalline structure of starches in the rice endosperm.

Physicochemical characterisation, digestibility and anticonstipation activity of some high‐resistant untraditional starches from zingiberaceae plants

SummaryTo find new starch sources with particular characteristics, five untraditional starches from zingiberaceae plants were studied about their physicochemical properties, digestibility and anticonstipation activity and compared with starches from traditional sources (potato and corn). All the five starches presented the shape of triangular, with visible thin sheet, which were significantly different from conventional sources. The crystal type of these five starches was B‐type pattern. Swelling power at 75 °C was negatively correlated with crystallinity. There was no significant difference in amylose content between starches from rhizome and tuber of Curcuma phaeocaulis Val., while they displayed significant variability in RS content. Starches from rhizome of Curcuma kwangsiensis, Curcuma wenyujin, Curcuma phaeocaulis Val. and Curcuma longa L. possessed much higher resistant starch content (range from 87.06% to 95.40%) and could better prevent constipation than potato and corn starches, which made them potential for managing diabetes and improving defecation conditions.

Physicochemical characterization of starch from hexaploid triticale (X Triticosecale Wittmack) genotypes

The starch granules of complete and substituted triticale genotypes were analyzed for morphology and size distribution using scanning electron microscopy (SEM) and laser diffraction, respectively. A quantitative comparison of total carbohydrate, starch, and amylose contents was also performed. The results showed that the complete triticales contained 8.8% more total carbohydrate content and 13.8% more starch content than the substituted ones. No significant differences in the average amylose content (22.8%) were observed between the two sets of triticales. However, the A- and B-type starch granules of the substituted triticales showed significant differences in amylose content. Starch granule distribution profiles showed that the sizes of the A- and B-type starch granules of complete triticales were larger (in the range of 18–41 μm and 2–13 μm, respectively) than those of substituted triticales (in the range of 8–38 μm and 0.5–6 μm, respectively). This study demonstrated that the starch in triticale genotypes differs in physicochemical properties.

Development of mucoadhesive buccal films from rice for pharmaceutical delivery systems.

The aim of this work was to investigate the suitable rice varieties for developing pharmaceutical buccal films. Two rice varieties with extreme difference in amylose content were used. Rice powders were chemically modified to yield the carboxymethyl rice prior to film preparation. Scanning electron microscope (SEM) and X-ray diffractometer (XRD) were used to investigate the solid structure of rice powders. The results indicated that amylose content in the rice grains played the effects on the morphology and crystalline structure of the modified rice powders as well as the film properties. The modified rice powders of low amylose content showed halo pattern XRD whereas some crystalline peaks could be observed from the high amylose content modified rice powders. Adding of glycerin caused the films better properties of more transparency and getting rid of air bubbles. High amylose rice films showed more transparency and higher mucoadhesive property and was considered to be suitable for incorporating the drug. Adding of surfactant caused the increase in tensile strength and decrease in elongation of the rice films. The most suitable surfactant for diclofenac buccal rice film is Tween 20. This study demonstrates that rice grains are the promising natural source for pharmaceutical film forming agent. Suitable pharmaceutical buccal films could be developed from the rice with high amylose content.

Effect of genotype and environment on the concentrations of starch and protein in, and the physicochemical properties of starch from, field pea and fababean.

The effects of genotype and environment and their interaction on the concentrations of starch and protein in, and the amylose content and thermal and pasting properties of starch from, pea and fababean are not well known. Differences due to genotype were observed in the concentrations of starch and protein in pea and fababean, in the onset temperature (To) and peak temperature (Tp) of gelatinization of fababean starch, and in the pasting, trough, cooling and final viscosities of pea starch and fababean starch. Significant two-way interactions (location × genotype) were observed for the concentration of starch in fababean and the amylose content, To, endothermic enthalpy of gelatinization (ΔH) and trough viscosity of fababean starch. Significant three-way interactions (location × year × genotype) were observed for the concentration of starch in pea and the pasting, trough, cooling and final viscosities of pea starch. Differences observed in the concentrations of starch and protein in pea and fababean were sufficient to be of practical significance to end-users, but the relatively small differences in amylose content and physicochemical properties of starch from pea and fababean were not.

Determination of Amylose Content and Its Relationship with RVA Profile Within Genetically Similar Cultivars of Rice ( Oryza sativa L. ssp. japonica)

Anther culture pure lines with antisense Wx gene were generated by Agrobacterium tumefaciens-mediated co-transformation followed by anther culture in transgenic rice ( Oryza sativa L. ssp. japonica). The antisense Wx transgenic pure lines were used to analyze the differences and the relationship between RVA eigenvalues among the lines with different amylose contents. 77 pure lines of anther culture having antisense Wx gene were studied for the amylose content of its offspring cultivar, Wuyunjing 7. It was found that levels of amylose content were similar to the control in 19 lines (16.0%); 1-5% lower than control in 50 lines, of which, within 11.0-13.9% in 40 lines; and 3.1-4.0% in 8 lines. The effect of the amylose content on RVA eigenvalue was analyzed through the RVA profile graphic comparison and test of significance for RVA eigenvalues. The analysis of RVA profiles with different amylose contents indicated that there were two kinds of RVA profiles within genetically similar cultivars. The lines with 3.1-4.0% of amylose content were distinctly different from other lines and conventional glutinous rice. The comparison of the similarity curve of RVA profile of the lines with different amylose contents showed that the lines with lower amylose content had a distinguished RVA profile with the curve increasing gradually, but not exceeding the first apex. The test of significance for eigenvalues of the RVA profile in the lines with different amylose contents indicated that there were five eigenvalues remarkably different among the lines with 3.1-4.0% of amylose content compared with other two groups. Further, there were three eigenvalues remarkably different among the lines with 11.0-13.5% of amylose content compared with control group. An optimized mathematical model, which characterizes the relationships between the amylose content and RVA eigenvalue, has been established in this study. From this model, it was clearly indicated that the parameters PeT and SBV were more related to amylose content. It was concluded that the differences in amylose content not only affected the eigenvalues of RVA but also caused different RVA profiles within genetically similar cultivars. The introduction of antisense Wx gene could lead to reduce the amylose content and lay theoretical foundation for quality improvement in rice breeding programs.

Genetic Effect of PUL Allelic Variation on Rice Cooking and Eating Qualities

Pullulanase (PUL) is a type of starch debranching enzymes involved in starch biosynthesis. To test the effect of PUL allelic variation on cooking and eating qualities in rice ( Oryza sativa L.), 2 sets of near-isogenic lines (NILs) for PUL gene were developed by crossing and backcrossing Guichao 2 ( indica) and Suyunuo ( japonica glutinous) and selected with the help of the gene-specific STS marker on PUL gene. The NILs had no significant differences in amylose content, gel consistency, and starch crystalline structure compared with their corresponding recurrent parents. In contrast, the starch paste viscosity and starch thermal property changed obviously between the NILs and their recurrent parents. It was concluded that PUL gene plays an important role in determining rice grain cooking and eating qualities, and functional differentiation occurred at the PUL locus between indica variety Guichao 2 and japonica variety Suyunuo. The gene-specific molecular marker for PUL gene developed on the basis of genomic sequence diversity could be directly applied in rice good quality breeding program.

米を中心とする穀物胚乳澱粉の構造と物性に関する研究

1． 近年わが国で育成された米品種の胚乳澱粉の構造と物性 近年わが国で育成されたモチ米，低アミロース米，中アミロース米，高アミロース米の4タイプの米試料の胚乳澱粉の性質を調べた．ウルチ性澱粉の真のアミロース含量とRVAによるピーク粘度との間に高い負の相関関係が観察された．高アミロース米の中には，見かけのアミロース含量は約30%と同様であるが，アミロペクチンの超長鎖含量，RVAのピーク粘度，セットバックが異なる性質を示す澱粉をもつ試料米が存在していた．アミロペクチンの超長鎖含量とRVAによる糊液のセットバックとの間に高い正の相関関係が観察されたことから，アミロペクチンに存在する超長鎖は澱粉糊のセットバックに大きな影響を及ぼすと考えられる．アミロペクチンの短鎖領域の側鎖長分布と超長鎖含量の両方とも，米澱粉の糊化温度に大きな影響を及ぼす．75°Cの水中で米澱粉を加熱する際，アミロペクチンに存在する超長鎖は，澱粉の膨潤および溶解に対して，いずれも関与しない傾向がみられた．2． アジアとその他の諸外国の品種米の胚乳澱粉の構造と性質 アジアとその他の諸外国の75品種米から胚乳澱粉を調製した．インディカおよび中国インディカのウルチ性品種米の澱粉は，見かけのアミロース含量，アミロペクチンの超長鎖含量ともに高い値を示し，アミロペクチンの最も短い側鎖画分(6-12量体，Fr.A)は低い値を示した．Fr.A含量は米澱粉のDSCによる糊化ピーク温度と負の関係が観察された．また，米澱粉中のWxタンパク質量と超長鎖含量との間に高い正の相関関係が得られた．米の胚乳澱粉の分類方法の一つとして，アミロペクチンの超長鎖含量とFr.A含量の間の関係を示すことを提案した． 3． 澱粉合成酵素の変異が澱粉の性質に及ぼす影響 ジャポニカ米の日本晴を遺伝的背景にもち，インディカ米のカサラスの染色体断片を含む3種の準同質遺伝子系統(NIL(Wxa)，NIL(SSIK)，NIL(Alk))の米試料を用いて，3種の澱粉合成酵素GBSSI，SSI，SSIIaが澱粉の性質に及ぼす影響を調べた．Wxa遺伝子によって日本晴とカサラスとの間のアミロース含量の違いをほぼ説明することができた．またWxa遺伝子によって澱粉のピーク粘度，ブレークダウンは減少した．NIL(Alk)のアミロペクチンは，6-11量体の短い側鎖が少なく，13-23量体の中鎖の多いカサラスと非常によく似た鎖長分布を示した．またDSCによる熱測定により，NIL(Alk)の炊飯米の老化速度が速いことがわかった．

Grain Qualities and Their Genetic Derivation of 7 New Rice for Africa (NERICA) Varieties

NERICA are interspecific rice varieties from crossing between the high-yielding Asian rice ( Oryza sativa spp. Japonica) with locally adapted African rice ( Oryza glaberrima). In this study, we analyzed grain qualities of 7 NERICA varieties (NERICA 1 to 7) and genetic derivation of quality-related genes. Quality analyses of NERICA grains showed that 7 NERICA varieties were clearly classified into two groups based on the difference of amylose content, and the difference influenced the pasting and physical properties of grains. Genetic analysis of the gene encoding granule-bound starch synthase I (GBSSI), which is known as a key enzyme on amylose synthesis in rice grain, revealed that varieties with higher amylose content ( approximately 29%) have the gene derived from O. glaberrima parent, and group 2 with lower amylose content ( approximately 22%) have the gene from O. sativa parent. These results indicated that the difference in amylose content as well as grain properties among 7 NERICA varieties is mainly determined by the genetic derivation of GBSSI. Further genetic analysis of starch synthesis-related genes suggested that the genetic derivation of SSIIa also influences the chain length of amylopectin in 7 NERICA varieties.

Influence of Starch and Gluten Characteristics on Rheological Properties of Wheat Flour Gel at Small and Large Deformation

ABSTRACTStarch and gluten were isolated from 10 wheat cultivars or lines with varied amylose content. The rheological properties of 30% wheat flour gel, starch gel, and the gel of isolated gluten mixed with common starch were determined in dynamic mechanical testing under shear deformation, creep‐recovery, and compression tests under uniaxial compression. Variation of wheat samples measured as storage shear modulus (G′), loss shear modulus (G″), and loss tangent (tan δ = G″/G′) was similar between flour and starch gels and correlated significantly between flour and starch gel. The proportion of acetic acid soluble glutenin exhibited a significant relationship with tan δ of gluten‐starch mixture gel. The small difference in amylose content strongly affected the rheological parameters of flour gels in creep‐recovery measurement. Wheat flour gel with lower amylose content showed higher creep and recovery compliance that corresponded to the trend in starch gel. Compressive force of flour gel at 50 and 95% strain correlated significantly with that of starch gel. Gel mixed with the isolated gluten from waxy wheat lines appeared to have a weaker gel structure in dynamic viscoelasticity, creep‐recovery, and compression tests. Starch properties of were primarily responsible for rheological changes in wheat flour gel.

Pasting Behavior of Amylose, Amylopectin and Their Mixtures as Determined by RVA Curves and First Derivatives

AbstractThe relationship between amylose to amylopectin ratio and functional properties of maize starch blends (system I) and “model mixtures” (system II) made of waxy and high amylose maize starch were investigated using the Rapid Visco Analyser (RVA). A 4‐5% difference in amylose content caused significant difference in RVA curves and their first derivatives. Based on the first derivative of the RVA curves four different parameters (Peak 2, Peak Time 2, Peak 3, Peak Time 3) were defined. Peak viscosity and parameters were negatively correlated with amylose content confirming that amylopectin is mainly responsible for water uptake. The final viscosity of starch was very high and decreased as amylopectin or amylose was added, indicating that this parameter is the most sensitive to interactions in starch. In system II amount and characteristics of amylopectin seemed to primarily determine the pasting properties. Traditional RVA curves and parameters proved to be feasible to detect the differences between gel properties of the two systems after cooling. First derivative viscograms and alternative parameters seemed to be suitable to demonstrate the importance of interactions between the starch components during gelatinization. Our results confirmed that the Rapid Visco Analyser is a sensitive rheological tool for evaluating effects of starch structure and chemical composition on functional properties providing valuable help for food technologists.