Physicochemical and Pharmaceutical Properties of Carboxymethyl Rice Starches Modified from Native Starches with Different Amylose Content

Carboxymethyl rice starches (CMRS) were prepared from nine strains of native rice starches with amylose contents of 14.7–29.1%. The reaction was conducted at 50°C for 120 min using monochloroacetic acid as a reagent under alkaline conditions and 1-propanol as a solvent. After determining the degree of substitution (DS), the physicochemical properties including water solubility, pH, and viscosity of 1% (w/v) solution, scanning electron microscopy (SEM), and X-ray diffraction (XRD) analyses of the granules, as well as some pharmaceutical properties of CMRS powders and pastes were investigated. The DS range was 0.25–0.40. All CMRS dissolved in unheated water and formed viscous gel. A good positive correlation was observed between amylose content and DS (r = 0.9278) but not viscosity. SEM and XRD concurrently revealed significant physical alteration of CMRS granules compared with those of native starches, which reflected the changes in the properties of CMRS. At 3% (w/w), CMRS can function as tablet binder in the wet granulation of both water-soluble and water-insoluble diluents. The tablets compressed from these granules showed good hardness with fewer capping problems compared with those prepared using the pregelatinized native rice starch as a binder. In addition, most CMRS pastes formed clear films with varying film characteristics, depending upon the amylose content of the native starches. This type of modified rice starch can potentially be employed as a tablet binder and film-former for pharmaceutical dosage formulations.     

Changes in Retrogradation Properties of Rice Starches with Amylose Content and Molecular Properties

The increases in storage modulus (G′), retrogradation enthalpy change (ΔH) and ΔH‐related Avrami kinetic parameters of gelatinized rice starch dispersions at 25% (w/w) were investigated with respect to storage period, amylose content (AC), and molecular properties. Three high‐AC and five low‐AC rice cultivars were compared for understanding the multiple influences of AC and molecular properties involved. After refining the results of correlation analysis, the G′ of just‐cooled samples changed positively, mainly with AC and additionally with the average chain length of amylose (CL_AM) and the weight ratio of extra‐long plus long chains to short chains of amylopectin (AP) (r_APchain). The developed ΔH on short‐term storage (10 days) elevated with increasing AC and CL_AM and decreasing degree of polymerization of AP (DP_AP), but after long‐term aging for one to three months with increasing r_APchain, especially for the low‐AC cultivars examined. Greater Avrami rate constants for retrogradation could be attributed to the combination of a lower DP_AP and r_APchain or AP chain length and a greater CL_AM. The polynomials using these critical factors to describe the retrogradation parameters were elucidated and could account for 85–99.6% of data deviations.     

Fine Structures of Starches from Long‐Grain Rice Cultivars with Different Functionality

The structural features of rice starch that may contribute to differences in the functionality of three long‐grain rice cultivars were studied. Dried rough rice samples of cultivars Cypress, Drew, and Wells were analyzed for milling quality, grain physical attributes, and starch structures and physicochemical properties. Drew was lower in head rice yield and translucency and higher in percentage of chalky grains compared with Cypress and Wells. Apparent amylose content (21.3–23.1%), crude protein (8.3–8.6%), and crude fat (0.48–0.64%) of milled rice flours were comparable, but pasting properties of rice flours as measured by viscoamylography, as well as starch iodine affinity and thermal properties determined by differential scanning calorimetry were different for the three cultivars. Drew had higher peak, hot paste, and breakdown viscosities, and gelatinization temperature and enthalpy. Molecular size distribution of starch fractions determined by high‐performance size‐exclusion chromatography showed that the three samples were similar in amylose content (AM) (20.0–21.8%) but differed in amylopectin (AP) (64.7–68.3%) and intermediate material (IM) (10.9–13.5%). Drew had highest AP and lowest IM contents, whereas Cypress had the lowest AP and highest IM contents. High‐performance anion‐exchange chromatography of isoamylase‐debranched starch indicated that the AP of Drew was lower in A and B1 chains but higher in B2, B3, and longer chains.     

Molecular Structure and Some Physicochemical Properties of High‐Amylose Barley Starches

The molecular structure and some physicochemical properties of starches from two high‐amylose cultivars of barley, high‐amylose Glacier A (HAG‐A) and N (HAG‐N), were examined and compared with those of a normal cultivar, Normal Glacier (NG). The true amylose contents of HAG‐A, HAG‐N, and NG were 41.0, 33.4, and 23.0%, respectively. Iodine affinities before and after defatting of starch, and thermograms of differential scanning calorimetry, indicated that HAG‐A and HAG‐N starches had a higher proportion of amylose‐lipid complex than did NG starch. The amylopectins from HAG‐A and HAG‐N were similar to NG amylopectin in average chain length (18–19), β‐amylolysis limit (β‐AL 56–57%), number‐average degrees of polymerization (DP_n 6,000–7,500) and chain length distribution. Very long chains (1–2%) were found in amylopectins from all cultivars. HAG‐A amylopectin had a larger amount of phosphorus (214 ppm) than the others. The amyloses from HAG‐A and HAG‐N resembled NG amylose in DP_n (950–1,080) and β‐AL (70–74%). However, HAG‐A and HAG‐N had a larger number of chains per molecule (NC 2.4–2.7) than NG amylose (1.8) and contained the branched amylose with a higher NC (9.5–10.6) than that of NG amylose (5.8), although molar fractions of the branched amylose (15–20%) were similar.     

Molecular and Gelatinization Properties of Rice Starches from IR24 and Sinandomeng Cultivars

The differences in pasting properties involving gelatinization and retrogradation of rice starches from IR24 and Sinandomeng cultivars during heating‐cooling processes were investigated using a Rapid Visco Analyser (RVA)and a dynamic rheometer. The results were discussed in relation to the molecular structure, actual amylose content (AC), and concentration of the starches. Generally, both starches possessed a comparable AC (≈11 wt%), amylose average chain length (CL), iodine absorption properties, and dynamic rheological parameters on heating to 95°C at 10 wt% and on cooling to 10°C at higher concentrations. In contrast to Sinandomeng, IR24 amylose had a greater proportion of high molecular weight species and number‐average degree of polymerization (DP_n). IR24 amylopectin possessed a lower DP_n and greater CL, exterior CL (ECL), and interior CL (ICL). Comparing the results of RVA analysis and dynamic rheology, the gelatinization properties and higher retrogradation tendencies of IR24 starch can be related to the structural properties and depend on starch concentration. In addition, the exponent n of starch concentration for storage moduli at 25°C (G′₂₅ ∝ Cⁿ) increased linearly with increasing AC.     

Effect of Nitrogen Rate and the Environment on Physicochemical Properties of Selected High‐Amylose Rice Cultivars

Genetic marker haplotypes for the Waxy and alk genes are associated with amylose content and gelatinization temperature, respectively, and are used by breeders to develop rice cultivars that have physicochemical properties desired by the parboiling and canning industries. Cultivars that provide consistent processing quality across diverse production environments are important to the industry. This study determined if measures of processing quality differed among cultivars, fertility treatments, and production environments. Nine cultivars having high amylose content (>23.0%) but with different Waxy and alk haplotypes were evaluated in three environments and using three nitrogen fertility levels. Although environment and fertility levels significantly (P < 0.05) impacted protein content, gelatinization temperatures, and peak, trough, and final paste viscosities, cultivars performed consistently across production environments and fertility applications. Differences were observed among cultivars in paste viscosity measures and gelatinization temperatures that corresponded with their Waxy and alk haplotypes. However, discriminant analysis revealed subgroupings within the same Waxy and alk haplotypes that were primarily differentiated by trough paste viscosity. The results of this study demonstrated that although these high‐amylose cultivars had consistent ranking across environments and nitrogen fertility regimes, there were differences in rice processing quality traits that were not apparent from their Waxy and alk haplotypes.     

Effect of Growth Location in the United States on Amylose Content,Amylopectin Fine Structure,and Thermal Properties of Starches of Long Grain Rice Cultivars

Starch was isolated from kernels of 27 rice samples consisting of nine U.S. long grain rice cultivars grown in three different locations (Missouri, Arkansas, Texas). Amylose (AM) content of the starches and the fine structure of the respective amylopectin (AP) were determined and used to explain differences observed in gelatinization properties. The AM content of rice cultivars grown at the lower temperature Missouri location increased 0.4–3% and 0.5–4% when compared with the same rices grown in Arkansas and Texas, respectively. AP values of the rice samples were isolated, debranched, and separated by low‐pressure size‐exclusion chromatography. The eluted AP linear chains were divided into three fractions to represent extra long (FrI), long (FrII), and short chains (FrIII). The corresponding average degree of polymerization (DP_n) at the peaks of fractions FrI, FrII, and FrIII were 100, 39, and 16, respectively. Total carbohydrate analysis of the fractions indicated that cultivars grown in Missouri had a consistently higher proportion of FrIII and lower proportion of FrII as the same cultivars grown in Arkansas and Texas. Furthermore, the Missouri samples showed a shift toward shorter DP_n in FrII and FrIII and had more of the shortest chain components (DP_n < 6) of AP. The proportion of FrI did not follow a trend and varied depending on the cultivar and across location. Thermal analysis indicated that the higher temperature growth environments (Arkansas and Texas) resulted in higher onset, peak, and heat of gelatinization for the starches, suggesting longer cooking time and higher heat requirement. Overall, the data support the nonfield findings of other researchers that higher growing temperature results in AP with more DP_n short chains that are within a range of DP >10 to form consistent crystallites, and thus results in higher gelatinization temperatures and enthalpies.     

Effect of Physicochemical Properties of High‐Amylose Thai Rice Flours on Vermicelli Quality

Certain physicochemical properties, including chemical composition, pasting, thermal parameters, and the gel texture of flour prepared from six cultivars of Thai rice with similar high‐amylose content were determined. These properties were correlated with the quality of vermicelli prepared from these flours for cooking and textural properties. Flour prepared from a Thai rice cultivar currently used for commercial production of vermicelli served as reference for these comparisons. Many similarities, but some significant differences, in the physicochemical properties were observed between the test rice flours and to the reference cultivar. Vermicelli prepared from all of the test rice flours were within an acceptable range for cooking quality but showed greater variation in textural quality. Among the physicochemical properties, gel hardness was well correlated with cooking and textural quality of vermicelli, and was useful for predicting overall vermicelli quality.     

Preparation and Properties of Starch Phosphates Using Waxy,Common, and High‐Amylose Corn Starches. I. Oven‐Heating Method

The structure and physicochemical properties of waxy, common, and high‐amylose corn starch phosphates prepared by oven heating were studied. Starch phosphates prepared by either slurry or dry‐mixing treatment before oven heating were also compared. The slurry treatment more efficiently incorporated phosphorus into starch relative to the dry‐mixing treatment under the reaction conditions studied. In general, the phosphorylated starch prepared by the slurry treatment exhibited a lower gelatinization temperature, a higher peak viscosity, a lesser degree of retrogradation, and improved freeze‐thaw stability compared with those prepared by the dry‐mixing treatment. Phosphorylation occurred probably in both amylose and amylopectin, and the amount and location of incorporated phosphate groups varied with starch types likely due to their different amylose and amylopectin contents. Waxy starch was more prone to phosphorylation, followed by common and high‐amylose starches, respectively.     

Characterization of Resistant Starch Samples Prepared from Two High‐Amylose Maize Starches Through Debranching and Heat Treatments

The aim of the present study was to investigate effects of debranching, autoclaving‐storing cycles, and drying processes (oven‐drying or freeze‐drying) on RS contents, thermal, pasting, and functional properties of high‐amylose maize starches (Hylon V and Hylon VII). The resistant starch (RS) contents increased (≤57.8%) with increasing autoclaving‐storing cycles. RS contents of oven‐dried samples were higher than those of freeze‐dried samples due to ongoing retrogradation of starch during oven drying at 50°C. Debranching caused a significant decrease in peak transition temperature and enthalpy values as compared with native starches. Solubility and water binding values of RS preparations were higher than those of native starches. Addition of native and autoclaved samples had improving effect on emulsion properties of albumin. Cold viscosity values of oven‐dried samples were lower as compared with freeze‐dried samples; this might be due to higher number of H‐bonds in the oven‐dried samples expected to be formed during drying. Debranching and autoclaving‐storing cycles caused decreases in peak, breakdown, and final viscosity values. The results of present study showed that debranching and heat treatments increased the RS contents and improved the functional properties of high‐amylose maize starches.     

Comparison of Methods for Amylose Screening Among Amylose‐Extender (ae) Maize Starches from Exotic Backgrounds

Breeding for high‐amylose corn requires a rapid analytical method for determining starch amylose so that generating wet chemistry values does not pose a major limitation in the volume of materials that can be screened. Two methods for determining apparent amylose content (AAC) were examined and compared with an iodine‐binding method involving the solubilization of isolated starch in a sodium hydroxide solution (method 1). These methods included one based on near‐infrared transmittance spectroscopy (NIRT) (method 2) and another iodine‐binding method involving the solubilizing of starch from ground whole corn with a DMSO‐iodine solution (method 3). These methods were chosen because, aside from initial set up costs, they are relatively rapid and inexpensive to perform. The materials evaluated consisted of various exotic corn populations including plant introductions and experimental materials generated from the Germplasm Enhancement of Maize (GEM) project. Crosses were made between these materials and a Corn Belt dent hybrid (OH43 × H99) converted with the amylose‐extender (ae) allele. Grain from F2 ears, presumed to be homozygous for the ae allele based on visual selection of mutant kernels on F1 ears from which they were planted, were then evaluated to identify possible modifiers of ae conditioning high starch AAC. From a total of 1,006 F2 ears, a core set consisting of 155 samples was established and only these were subjected to starch AAC analysis, using all three methods to compare the methods. Method 2 showed poor correlation to method 1 (r = 0.88), however, NIRT did appear to discriminate between samples converted to ae vs. those with a normal or possibly segregating endosperm type. Method 3 showed a slightly better correlation with method 1 (r = 0.92) and appeared to more fully discriminate among samples with AAC values >65% from those at ≈55%. Results from this study suggest that NIRT may be useful when a quick screening method is needed to discriminate mutant from nonmutant genotypes within grain samples of exotic germplasm especially when visual identification is difficult. In addition, method 3 could be used to replace the more time‐consuming method 1 when trying to identify high AAC levels among ae genotypes, even though some inconsistency was observed between the two methods. Finally, this study revealed that exotic germplasm may be an important source of new modifiers to the ae allele because values as high as 70% AAC were identified.     

Resistance to α‐Amylase Digestion in Four Native High‐Amylose Maize Starches

Native and processed high‐amylose maize starch (HAMS) is an important source of resistant starch (RS). The objectives of this work were to use an in vitro procedure to estimate the RS content of native granules from a series of ae‐containing HAMS genotypes, and to examine the nature of the α‐amylase resistant starch (ARS). By the method of Englyst et al (1992), RS for ae V, ae VII, ae su2, and ae du were estimated to be 66.0, 69.5, 69.5, and 40.6%, respectively. By transmission electron microscopy, most of the residual granules from ae V, ae VII, and ae su2 showed little evidence of digestion. Partially digested granules had a radial digestion pattern in the interior and an enzyme‐resistant layer near the surface. Size and chain‐length profile of constituents of ARS were similar to those of the native HAMS (unlike type 3 RS), consistent with complete hydrolysis in susceptible granule regions. Between crossed polarizers, many iodine‐stained native and residual HAMS granules had blue centers and pink exteriors, which may be due to a difference in orientation of the amylose‐iodine complexes in the exterior. Four granule color types were observed for ae du, differing in enzyme resistance. The high‐enzyme resistance of native HAMS granules may result from altered granule organization, which appears to vary among and within granules from ae‐containing genotypes.     

Properties of Starches from Near‐Isogenic Wheat Lines with Different Wx Protein Deficiencies

To determine the effect of amylose content on the starch properties, the amylose content, pasting properties, swelling power, enzymatic digestibility, and thermal properties of partial and perfect waxy types along with their wild‐type parent were analyzed. As expected, amylose content decreases differently in response to the loss of each Wx gene, showing the least response to Wx‐A1a. Most of the characteristics, except the thermal properties of the amylose‐lipid complex in differential scanning calorimetry (DSC), differed significantly among the tested types. Furthermore, the breakdown, setback, and pasting temperatures from the Rapid Visco Analyser (RVA) and the enzymatic digestibility, swelling power, peak temperature, and enthalpy of starch gelatinization from DSC showed a correlation with the amylose content. The relationships between the peak viscosity from the RVA and the onset temperature of starch gelatinization determined by DSC with amylose content of the tested materials were not clear. Waxy starch, which has no amylose, showed a contrasting behavior in starch gelatinization compared with nonwaxy starches. Among the nonwaxy starches, lower setback, lower pasting temperature, higher enzyme digestibility, higher peak temperature, higher enthalpy of starch gelatinization, and higher swelling were generally associated with low amylose starches.     

不同中薯系列马铃薯淀粉组成与理化性质的差异分析

为分析不同品种马铃薯淀粉组成与理化性质的差异,本研究以15个不同品种中薯系列马铃薯为原料提取淀粉,并对其组成和理化性质进行了检测及相关性分析。光学显微镜和扫描电镜结果表明,马铃薯淀粉颗粒的粒径分布范围广,颗粒形貌存在差异,小颗粒多为卵圆形,大颗粒多为椭圆形、拉长形以及不规则形。不同马铃薯淀粉的理化性质存在显著差异,其溶解度、膨润力范围分别为25.92%~28.74%,4.90~6.26 g·g^-1;糊化初始温度(T_o)、峰值温度(T_p)、终止温度(T_c)、糊化焓值(ΔH)范围分别为61.44~65.55℃、64.49~68.69℃、67.87~72.54℃、7.21~13.49 J·g^-1;峰值黏度、衰减值、回生值范围分别为2 499.3~3 220.4、514.0~2 218.4、401.0~884.1 BU。相关性分析结果表明,马铃薯淀粉中磷含量与峰谷黏度呈显著正相关,与溶解度呈显著负相关;平均粒径D[4,3]与短程有序参数1 045/1 022 cm^-1 和1 022/995 cm^-1均呈显著正相关;T_o与峰值黏度呈显著负相关;糊化温度与峰值黏度和崩解值均呈显著负相关,与峰谷黏度、最终黏度和回生值均呈显著正相关。本研究结果可为中薯系列马铃薯淀粉在食品加工中的应用提供科学依据。     

Kernel and Starch Properties of U.S. and Imported Medium‐ and Short‐Grain Rice Cultivars

The production of medium‐ and short‐grain rice in the mid‐Southern U.S. rice‐growing region is increasing. This work aimed to identify the quality traits of importance to the markets for these grain types. Twenty‐five medium‐ and short‐grain milled rice samples were collected and analyzed for physical, gelatinization, pasting, and starch structural properties. Six samples were from Arkansas (AR), five from California (CA), and 14 imported (IM). Cluster and principal component analyses showed that the AR samples had greater gelatinization temperature, enthalpy, and percentages of amylopectin long chains (B2 and B3 chains) but lesser kernel whiteness, total setback viscosity, and percentage of amylopectin short chains (A chains) than the CA samples. With the exception of one sample from Taiwan, chemometrics indicated that the IM samples differed from the AR samples (cluster A) in some properties and were grouped into three clusters (clusters B, C, and D). Cluster B samples had properties that were similar to the CA samples; cluster C samples had lower gelatinization temperature and peak viscosity but greater percentages of amylose and A chains than the AR samples; and cluster D samples had lesser paste breakdown but greater final viscosity and percentage of B1 chains than the AR samples. Kernel width, color, and chalk were the primary sources of variation in milled rice appearance. In relation to structure and functionality, the percentages of amylopectin A and B3 chains and amylose content were the major sources of variation.     

Rheological Properties of Dispersions of Spherulites from Jet‐Cooked High‐Amylose Corn Starch and Fatty Acids

High‐amylose corn starch was cooked in an excess‐steam jet cooker in the presence of 5% oleic or palmitic acid, based on amylose. The cooked product was rapidly cooled in an ice bath and then freeze‐dried or drum‐dried. Amylose was removed from solution by forming helical inclusion complexes with the fatty acid, and the inclusion complexes formed submicron spherical particles upon cooling. The dried material was reconstituted to form a paste that exhibited gel‐like properties upon standing, but that flowed readily when shear was applied. The rheological properties of these pastes were measured to determine the effects on the flow properties of 1) the solids concentration in the reconstituted paste, 2) the method of sample drying and reconstitution, and 3) the fatty acid used. The materials were very spreadable, and at the highest concentrations their flow properties were similar to a commercial shortening. The pasting properties of the dried solids were also examined.     

Physicochemical and Functional Properties of Protein Isolates Obtained from Several Pea Cultivars

The goal of this research was to investigate the physicochemical and functional properties of protein isolates obtained from several pea cultivars grown at two locations in Canada. The functionalities of the pea protein isolates (PPIs) were then compared with those of commercial food protein ingredients derived from milk, egg, pea, soy, and wheat. Six pea cultivars (Agassiz, CDC Golden, CDC Dakota, CDC Striker, CDC Tetris, and Cooper) were collected from two years over two locations in Saskatchewan (Canada). Samples were evaluated for composition, surface properties, and functional properties. All PPIs had protein levels of ≈91% (db) and isolate and protein yields of ≈18 and ≈72%, respectively. Cultivars exhibited legumin/vicilin ratios from 0.36 (Agassiz) to 0.79 (CDC Golden). Differences among cultivars as well as significant cultivar × environment interactions were found only for maximum intrinsic fluorescence (195–267 arbitrary units), solubility (63–75%), and foaming capacity (167–244%). No differences owing to either cultivar or environment were observed for surface charge (zeta potential = approximately –24 mV), oil holding capacity (≈3.2 g/g), foam stability (≈75%), or emulsion stability (≈96%). Relative to the commercial isolates, PPIs prepared under laboratory conditions behaved most similarly to soy isolates, with the exception of solubility. Whey and egg were superior in solubility and foaming properties, whereas wheat and the commercial pea protein product were significantly lower in nearly all of the functionality tests. Based on their oil holding properties, the laboratory‐prepared PPIs may serve as good meat extenders. The findings also suggest that pea processors may not need to specify either the cultivar or the environment when acquiring raw material, thus creating advantages in their feedstock sourcing.     

Morphologies and Thermal Properties of Hydroxypropylated High‐Amylose Corn Starch

High‐amylose (80%) corn starch was modified by hydroxypropylation with different molar substitution (MS). The unique microstructure of high‐amylose starch keeps its granules intact after hydroxypropylation. However, the microstructures and thermal properties strongly depend on the MS of hydroxypropylation. With increasing MS, the granule size was increased, which is partly due to disrupted granule structure, particularly in the amorphous region. Unlike normal starch, the modified high‐amylose corn starch showed a narrow gelatinization range measured by differential scanning calorimetry (DSC), which can be explained by destruction of amylose‐lipid complex. Internal microstructures and morphologies of hydroxypropylated starch were investigated using confocal laser scanning microscopy and to further explore the mechanism of chemical reaction and phase transitions.     

Probing the Properties of Dough with Low‐Intensity Ultrasound

Ultrasonic assessments of the properties of dough have been used over the past 15–20 years to complement studies of dough properties that use other physical testing techniques. After the principles and techniques of low‐intensity ultrasound are introduced, its use as a tool for investigating the rheology and structure of dough is reviewed. One important outcome from ultrasonic assessments of dough properties is an understanding of how bubbles alter dough rheology.