Low-amylose Rice Research Articles

Rice with lower amylose content could have reduced starch digestibility due to crystallized resistant starch synthesized by linearized amylopectin.

High resistant starch (RS) rice with a low glycemic index (GI) is digested more slowly, resulting in a slow increase in the postprandial blood glucose level. People with milled rice as a staple diet, and with sedentary lifestyles, are more prone to acquire type 2 diabetes in the long term. With an increasing population of diabetics worldwide, one possible solution is the development of rice-based, low-GI foods with high RS content rice. In addition to amylose content (AC), linear chains of amylopectin also affect the rate of starch digestibility. The values of GI (52.49-63.0), RS (0.64% to 2.28%), and AC (3.82% to 24.52%) were found to vary widely in 110 rice genotypes. Genotypes IG 23 and IG 40, with contrasting AC (15.65% and 24.52%, respectively), revealed that amylose alone did not affect digestion rate. Starch morphology, bioaccessibility, and pasting properties differed noticeably among genotypes. A starch debranching enzyme pullulanase assay indicated the role of the linear amylopectin chain in crystallized RS formation within the grains of lower AC genotype IG 23. Enhanced activity of the starch-debranching enzyme pullulanase produced linearized amylopectin resulted into reduced starch digestibility in low-amylose rice. This is probably the first report on the natural presence of high RS (crystallized) in rice with lower AC (IG 23). Development of rice-based food with low GI and high RS could be a promising strategy for lowering the prevalence of type 2 diabetes. © 2024 Society of Chemical Industry.

The Consumption of High-Amylose Rice and its Effect on Postprandial Blood Glucose Levels: A Literature Review.

Background/Objectives: Rice is a major staple in the diets of East Asian populations. Numerous meta-analyses have shown an association between high white rice consumption and a higher risk of diabetes. High-amylose rice (varieties with over 25% amylose content) is absorbed more slowly in the gut compared to low-amylose rice, and it results in lower levels of postprandial blood glucose. Various intervention studies have investigated the effects of high-amylose rice consumption on postprandial blood glucose and the glycemic index. The quantity of the research suggests that a comprehensive review of these diverse findings is necessary. Methods and Results: We reviewed 17 clinical trials, most of which showed that high-amylose rice ingestion results in lower postprandial blood glucose levels and glycemic index compared to low-amylose rice diets. Although they differed in their sample size, study design, rice type and quantity, and amylose content, most of these studies suggested that there is a reasonable effect of high-amylose rice consumption on postprandial blood glucose. In particular, the effect on blood glucose suppression tended to be related to the amylose content. However, long-term intake studies are still limited and require further investigation. Conclusions: In conclusion, high-amylose rice shows promise for blood glucose management.

Fine structure of starch biomacromolecules and digestibility: The regulative role of amylose and amylopectin in the digestive hydrolysis of starch in rice

The digestibility of starch in staple foods has rarely been examined at the bio-macromolecular level. This study addresses this by investigating the fine structures of amylose and amylopectin to understand their roles in starch digestibility in cooked white rice. Using the static INFOGEST protocol and oral processing by human volunteers, we assessed the starch digestion characteristics of 13 rice varieties, with amylose and amylopectin chain length distribution being analyzed using size-exclusion chromatography and high-performance anion exchange chromatography, respectively. Kinetic modelling revealed that chewed white rice follows a typical parallel digestion pattern, with rapidly (SF) and slowly digestible starch (SS) being digested simultaneously at distinctly different rates. Amylose content (AC) and amylose weight were significantly and positively correlated with the digestion rate and extent of SS, whereas the digestion rate and extent of SF were closely linked to amylopectin, particularly its short and intermediate chains (degree of polymerization 13–36). Compared to low-amylose rice (AC < 25 %), high-amylose rice exhibited significantly higher SS but with a lower digestion rate, attributed to its higher AC with shorter chains and fewer short to intermediate Ap branches. These findings provide insights into starch structure-digestibility relationships, aiding the development of rice varieties with slower digestion rates.

Varieties and cooking conditions difference in quality of instant brown rice

Amylose content is an important indicator that determines the hardness and softness of rice, which depends on rice varieties. Three types of specialty colored rice in Vietnam were selected for research on instant rice production including DH6 brown rice (DH6), Huyet Rong rice (HR), and Cam Cai Lay rice (CL). Proximate compositions and antioxidant properties such as total anthocyanin and total phenolic content in three kinds of rice were analyzed and compared. In addition, the effect of varieties and ratios of rice and water on the cooking time, volume expansion, antioxidant compounds and sensory properties were observed. The results showed that varieties led to differences in the nutritional profile of rice. CL and HR have the highest anthocyanin content (54.9-56.5 mg/100 g). DH6 brown rice is considered as the low amylose rice, with the content of amylose about 4.6%. Besides, it was also found that using “Cam Cai Lay” rice could create products with good structure and high sensory value. The results also confirmed that the product is of good quality when using a ratio of rice: water 1:2 and a cooking time of 30 mins. Types of rice and cooking conditions remarkably affected the quality of instant rice, which could further optimize for the up-scale process.

Effect of proteins and gums on rheology of rice flour, quality characteristics and estimated glycaemic index of low amylose rice gluten‐free penne

SummaryGluten‐free rice penne (GFRP) was developed from low amylose rice flour by incorporating egg white protein, soy protein isolate, guar gum and xanthan gum to produce penne with low estimated glycaemic index (eGI). The rheology of rice flour, textural properties, cooking quality, resistant starch (RS) and eGI of GFRP were investigated. Addition of proteins and hydrocolloids increased the storage modulus (G′) and loss modulus (G″). Rice gel with proteins and hydrocolloids formed a stronger and more elastic gel than the control, with highest G′ observed in rice gel with 5% egg white protein and 1% guar gum. Incorporation of proteins and hydrocolloids in GFRP significantly increased firmness, improved cooking quality and increased RS content. The eGI of GFRP added with egg white protein and guar gum reduced from seventy‐one to fifty‐three. Results suggested that the development of low eGI penne was possible by incorporating egg white proteins and guar gum.

Effects of Binding between Ca in Hard Water and Phosphorus in Amylopectin on the Qualities of Boiled Rice and Rice Noodle Prepared by Soaking and Boiling in Hard Water.

Recently, global warming has led to an increase in chalky rice grains. This has consequently resulted in the deterioration in quality of rice products. Although we previously reported that hard water, rich in Ca, is useful for the quality improvement of high-temperature-damaged rice grains, the mechanism was not elucidated sufficiently. Therefore, we used various kinds of rice cultivars, from waxy to high-amylose ones, for soaking and boiling in hard water and compared physical and chemical properties of the products. It was shown that the degree of quality improvement, such as final viscosities in pasting property, and textural properties of boiled rice, was more remarkable for high-amylose rice than low-amylose rice. As we found that the phosphorus contents showed positive correlations with amylose and long chains of amylopectin, we estimate that the effects are mainly due to binding of calcium and phosphorus. Because that high-amylose or long-chain-rich amylopectin rice cultivars showed high calcium contents in rice products, these rice cultivars would be very useful to supply calcium through dietary intake via hard water cooking.

Effect of nitrogen fertilizer on the quality traits of Indica rice with different amylose contents.

Nitrogen is a key factor affecting the quality of rice. Studying the impact of nitrogen fertilizer on the taste, physicochemical properties, and starch structure of Indica rice with different amylose contents is of great significance for scientifically fertilizing and cultivating high-quality rice varieties for consumption. The results indicate that increasing nitrogen fertilizer application reduces the amylose content and increases the protein content, resulting in a decrease in taste quality. Simultaneously, it reduces the intergranular porosity of starch particles, improving the appearance and milling quality of rice. Compared to the N1 treatment (nitrogen fertilizer application rate of 90 kg ha-1), the taste of low-amylose rice (Yixiangyou 2115) and high-amylose rice (Byou 268) decreased by 14.24% and 19.79%, respectively, under N4 treatment (nitrogen fertilizer application rate of 270 kg ha-1). The effect of nitrogen fertilizer on low-amylose rice is mainly reflected in increased rice hardness, enthalpy value, and setback viscosity, resulting in a decline in taste. The effect of nitrogen fertilizer on high-amylose rice is mainly reflected in a decrease in peak viscosity, an increase in gelatinization temperature, and crystallinity under high nitrogen levels. Increasing nitrogen fertilizer application can improve the appearance and milling quality of rice, but it also leads to an increase in protein content, hardness, gelatinization enthalpy, decrease in breakdown value, and a decline in palatability. In practical production, different production measures should be taken according to different production goals. © 2024 Society of Chemical Industry.

Physicochemical, functional, pasting, and amino acid compositions of milled rice, and extrusion behavior of milled rice from basmati and nonbasmati varieties

AbstractBackground and ObjectivesThis study was carried out to evaluate the difference in physiochemical, functional, cooking, textural, and pasting properties along with amino acid profile of nine basmati and nine nonbasmati rice varieties. Principle component statistical analysis was done to analyse the relationships among different properties of these varieties. Some verities containing high amylose content and good amino acid profile were selected for further development of extruded products (rice extrudates).FindingsVariations were observed in the physicochemical and functional properties of basmati and nonbasmati varieties. Low amylose rice varieties had higher cooking time, firmness, pasting temperature, and lower pasting viscosity. Selected high amylose‐containing varieties were showed higher bulk density but lower expansion ratio and hardness of rice extrudates. Result of this study will help industry for selection of rice for development of gluten‐free rice‐based breakfast cereals, puffed rice snacks, and so forth.ConclusionsAmong all varieties, PR122, PR128, PB3, PB4, and PB1121 exhibited higher levels of ash content, amylose content and protein content. Consequently, these varieties demonstrated longer CT, greater GSL, higher cooked grain firmness, and higher pasting PT, although they exhibited lower PV. PB1637, PB1509, PB1121, and PB4 displayed higher levels of essential AAs and sweet taste attributing amino acids, such as serine, glycine, and alanine, when compared to the other varieties. The results showed that rice containing higher amylose had lower expansion ratio of the extrudates, while higher bulk density and hardness. PR126 and CSR30 had the highest expansion ratio among the varieties that have been evaluated. Based on these results, PR126 and CSR30 could be used to make gluten‐free rice‐based breakfast cereals, rice snacks, and instant products.Significance and NoveltyPhysiochemical, functional, cooking, texture, pasting properties as well as amino acid profile were evaluated of different basmati and non‐basmati Indian (Punjab) varieties. Principle component (Relationship) analysis between various properties and different rice varieties was carried out. Extrusion is the most versatile processing technology used in the food industry to develop the product having better functional and sensory characteristics. The findings highlight the necessity of taking amylose content and amino acid composition into account when selecting rice types for preparation of extruded rice food.

Evaluation of Distintion, Homogeneity and Stability (DHS) Traits and Agronomic Value of Low Amylose Rice varieties under Growing Conditions in the Senegal River Valley

Evaluation of Distintion, Homogeneity and Stability (DHS) Traits and Agronomic Value of Low Amylose Rice varieties under Growing Conditions in the Senegal River Valley

Investigation of low amylose rice extrudates blended with germinated green gram and bhimkol flour

Ready-to-eat breakfast cereals (RTEBCs) have been developed from low-amylose rice by incorporating germinated green gram and bhimkol flour. A four variable central composite design (CCD) was used to evaluate the effects of independent variables on product responses, viz. blend ratio (80:10:10–60:30:10) of low-amylose rice flour, germinated green gram and bhimkol), screw speed (200–400 rpm), barrel temperature (90–130 °C) and feed moisture content (10.5–20.5%, wet basis), respectively. Extrudates developed in the optimized condition showed acceptable physic-chemical properties viz. EI (5.5) and BS (0.215 N/mm2), WAI (483.21 g/100 g), WSI (46.22 g/100 g), PV (484 cp) and FV (154 cp). The extrudates were found to have dietary fibre content and vitamin B1 content of 5.16% and 0.847 μg/g, respectively. MTT-proliferation study showed 75.45% survivality for extrudate made of low amylose rice blended with germinated green gram and bhimkol flour at maximum concentration of 50 mg/ml, respectively. Thus it was demonstrated that germinated green gram and bhimkol could be extruded to have a healthy RTBCs as well as weaning food.

The characterization of modified rice flour by combination of ultrasonication and acetylation process for biodegradable packaging

Acetylation in starch resulted in intermediate and high degree of substitution (DS) that has hydrophobic properties. However, it needs a long reaction time. A combination of ultrasonication and acetylation can speed up the acetylation process. This study aims to produce a higher DS of rice flour by the combination of ultrasonication and acetylation. The rice flour was processed in an ultrasonic bath to improve the acetylation. The modified rice flour was then characterized based on the morphology, physicochemical, and pasting properties. Results showed that ultrasonication treatment can speed up the acetylation process and enhance the DS value up to 2.68 times higher than acetylation without ultrasonication. In this case, the low amylose rice flour resulted in a higher DS value and lower solubility which implied higher hydrophobicity. Therefore, modified rice flour can be the potential for coatings as well as biodegradable packaging.

Development of low amylose rice (&lt;em&gt;Oryza sativa.&lt;/em&gt; L) variety at 309 for rice based confectionery production in Sri Lanka

Tropical Agricultural Research and Extension is a peer-reviewed international scientific journal covering a wide range of subject areas in tropical and subtropical agriculture published quarterly by the Faculty of Agriculture, University of Ruhuna, Sri Lanka. The journal is also available on the Faculty of Agriculture, University of Ruhuna website https://www.agri.ruh.ac.lk/tare/index.htm .

In vitro testing indicates an accelerated rate of digestion of starch into glucose of cooked rice with the development of low amylose rice in China.

The consumption of low amylose rice has substantially increased in China in recent years. This in vitro study showed that the starch digestion process was distinctly different between a group of commercial rice samples (CR, n=34) with low amylose content (14-20%) and a group of control rice samples (CK, n=16) with high amylose content (24-30%). In particular, the CR group had an active digestion duration that was∼90% shorter and a rate of glucose production within the active digestion duration that was nearly 50% higher compared to the CK group. The findings of this study indicate that the development of low amylose rice in China can result in an acceleration in the rate of digestion of starch into glucose of cooked rice, highlighting the need for in vivo assessment of the potential risk of diabetes associated with the consumption of low amylose rice.

Effects of konjac glucomannan on pasting, rheological, and structural properties of low-amylose rice starch

Abstract Blend of starch and polysaccharide is a secure and feasible modifying method for starch. Effects of konjac glucomannan (KGM) on pasting, retrogradation, rheological and structural properties of low-amylose rice starch were evaluated. KGM addition reduced the pasting temperature, breakdown and setback values, but raised the peak viscosity. When KGM concentration increased, the storage and loss moduli showed an upward trend. Fourier transform infrared spectroscopy (FTIR) showed redshifts at 3450 and 1640 cm−1 and suggested the formation of intermolecular hydrogen bond between KGM and starch molecules. X-ray diffraction (XRD) indicated that KGM decreased the relative crystallinity from 11.88 to 3.10%. Scanning electron microscopy (SEM) of KGM induced samples showed looser network structures, and confocal laser scanning microscopy (CLSM) detected less cloud-like blurry pastes surrounding around the starch ghosts. KGM addition suppressed the starch retrogradation. These results could be used to broaden the application of KGM in the food industry.

Pre-soaking treatment can improve cooking quality of high-amylose rice while maintaining its low digestibility.

Rice is a staple food for more than half of the world's population and it is regarded as a high glycemic index (GI) food. Breeders developed high amylose rice having low digestibility, but it also has inferior palatability. This study used high-amylose rice (HAR) produced by gamma irradiation and compared the digestion and physicochemical properties related to palatability with those of low-amylose rice (LAR). Pre-soaking and different-pH treatments were adopted to find a way to enhance the palatability of HAR while maintaining its low digestibility. After pre-soaking, HAR had a higher water uptake ratio (4.68 vs. 4.11 g g-1), proportion of leached starch (16.6 vs. 12.6%) and adhesiveness (77 vs. 39), but lower setback (0.092 vs. 0.107 Pa s), hardness (10.1 vs. 12.6 kg) and resilience (0.20 vs. 0.25). The results showed that pre-soaking was able to enhance the quality of the cooked rice mainly by modifying the starch amorphous region while maintaining the low digestibility of HAR. Pre-soaking can be adopted as a practical and effective household cooking method to prepare rice with relatively low digestibility and good palatability.

Probing a best suited brown rice cultivar for the development of extrudates with special reference to Physico-chemical, microstructure and sensory evaluation

Seven Pakistani brown rice cultivars (KS-282, SB, C-9, SUPRI, PK-386, IRRI-9 and IRRI-6) were investigated as an alternative raw material to develop directly expanded extrudates. Results indicated that bulk density remained constant in all rice cultivars, whereas SUPRI presented a higher length-breadth (LB) ratio and lower thousand kernel weight and starch content than other cultivars. Amylose content was higher in KS-282, C-9 and IRRI-9 and lowest in SB. SUPRI rice extrudates produced optimum expansion and crispiness with reduced hardness, piece and bulk density. Scanning electron micrographs showed more cell pockets and evenness in porosity per unit area in SUPRI brown rice extrudates, indicating more porous and crispier extrudates. It is also evidenced from the micrographs that cavities were evenly distributed and less ruptured in SUPRI brown rice. Consequently, SUPRI extrudates exhibited better microstructure, crispiness (No. of peaks 9), and porosity (0.838 ± 0.009) along with minimum piece density (0.038 ± 0.001 g/cm3) and hardness (17.85 ± 1.05 N). Conclusively, low amylose rice cultivar (SUPRI) perform better as substitute raw material for extrudates development.

Posttranslational Modification of Waxy to Genetically Improve Starch Quality in Rice Grain.

The waxy (Wx) gene, encoding the granule-bound starch synthase (GBSS), is responsible for amylose biosynthesis and plays a crucial role in defining eating and cooking quality. The waxy locus controls both the non-waxy and waxy rice phenotypes. Rice starch can be altered into various forms by either reducing or increasing the amylose content, depending on consumer preference and region. Low-amylose rice is preferred by consumers because of its softness and sticky appearance. A better way of improving crops other than downregulation and overexpression of a gene or genes may be achieved through the posttranslational modification of sites or regulatory enzymes that regulate them because of their significance. The impact of posttranslational GBSSI modifications on extra-long unit chains (ELCs) remains largely unknown. Numerous studies have been reported on different crops, such as wheat, maize, and barley, but the rice starch granule proteome remains largely unknown. There is a need to improve the yield of low-amylose rice by employing posttranslational modification of Wx, since the market demand is increasing every day in order to meet the market demand for low-amylose rice in the regional area that prefers low-amylose rice, particularly in China. In this review, we have conducted an in-depth review of waxy rice, starch properties, starch biosynthesis, and posttranslational modification of waxy protein to genetically improve starch quality in rice grains.

Polishing conditions in rice milling differentially affect the physicochemical properties of waxy, low- and high-amylose rice starch

Effect of polishing condition during milling of rice on the properties of rice starch was investigated. Waxy, low- and high-amylose rice were polished with different milling speeds (750, 950 and 1050 r/min) and milling durations (20, 40 and 60 s) to obtain polished rice. Rice starches were extracted from the polished rice. Swelling power and solubility index of low- and high-amylose rice starches increased with milling speed and duration compared with unpolished rice starches. However, for waxy rice starch, there was no significant change. The peak, trough and final viscosities decreased for waxy rice starch and increased for high-amylose rice starch with increased polishing, whereas those of low-amylose rice starch increased first and then decreased. Polishing induced greater pseudoplasticity in starch relative to that from unpolished rice. Polishing duration during milling caused greater changes in swelling behavior and pasting properties, whereas polishing duration caused greater effects on structural properties. This study showed that both polishing speed and duration impacted the physicochemical and rheological properties of different rice starches, but to a different extent.

Screening of Local Rice Varieties Grown in Khyber Pakhtunkhwa; Blending High Amylose Rice Flour Modified Functional and Pasting Profile of Low Amylose Rice Flour

Screening of Local Rice Varieties Grown in Khyber Pakhtunkhwa; Blending High Amylose Rice Flour Modified Functional and Pasting Profile of Low Amylose Rice Flour

Quality of gluten-free cookies made with rice flour of different levels of amylose and cowpea beans

PurposeThe objective of this study was to evaluate the effects of rice flour obtained from rice grains with different levels of amylose on technological, nutritional and sensory properties of cookies made with a blend of rice and cowpea flour.Design/methodology/approachThe cookies preparation was set at a ratio of rice flour and cowpea beans 70:30. The studied formulations were: LA: low amylose rice flour; MA: medium-amylose rice flour; HA: high amylose rice flour. The quality of the obtained cookies was analyzed for proximate composition, in vitro protein digestibility, thickness, diameter, dispersion factor, texture, color, amino acid profile and sensory properties.FindingsProximate composition and in vitro protein digestibility showed no differences between the three studied formulations. The medium and low amylose rice flour cookies showed the lowest hardness values. The combination of rice and beans allowed a good balance of essential amino acids. The cookies formulated with high amylose rice flour presented lighter coloration, low hardness and greater sensory preference.Originality/valueRice and cowpea flours are an alternative source for the preparation of gluten-free bakery products, such as cookies. The high amylose content of rice flour has less negative interference in the texture characteristics of the cookies. The combination of rice and beans flour provides a balance of essential amino acids.