Amylose Content Research Articles

Enhancing Productivity and Antioxidant Activities in Thai Colored Rice Cultivars ‵RD69′ and ‵Hawm Gulahb Deang′ Using Chitin-Based Material and Rice Husk

Rice is the major crop of Thailand. However, the rice yield is still limited, especially in local cultivars. Fermented chitin (FC) application to soil has been demonstrated to improve rice growth and yield. The application of biostimulants has been proposed to improve both the yield and quality of ‛RD69’ and ‛HGD’ rice varieties. While FC has been suggested as a potential solution, the specific effects of FC on seed quality and quantity remain insufficiently explored. In this study, pot experiments were conducted to determine the effects of FC and FC with rice husk (FC+RH) treatments on the grain quantity and quality of two rice cultivars, ‛RD69’ and ’Hawm Gulahb Deang’ (HGD), which are colored rice varieties with high antioxidant levels. ‛RD69’ has low apparent amylose content (AAC) and a high percentage of rapidly available glucose (RAG), while ‛HGD’ is the local Thai rice with medium AAC and low %RAG. FC and FC+RH were applied as soil supplements at concentrations of 0.01%, 0.1%, and 0.2% (w/w). The supplementation of 0.2% FC+RH resulted in the highest yield of ‛RD69’ (73%) and ‛HGD’ (30%). Although both FC and FC+RH did not significantly affect the AAC content of both cultivars, FC+RH decreased their %RAG. Interestingly, although FC+RH enhanced the antioxidant activity of the seeds of both cultivars, ‛RD69’ was more responsive to the effects of FC and FC+RH treatments than ‘HGD’, as significantly higher antioxidant levels were detected in ‛RD69’ seeds. These findings suggest that FC+RH supplementation can enhance the yield and quality of colored rice.

Optimization of ultrasound-assisted extraction of mango cotyledon starch: Physicochemical, structural, thermal and functional properties

Mango (Mangifera indica L.) seed, a byproduct of mango pulp and juice processing, is recognized for its abundant starch content. The advancement of the modern food industry has prompted a shift away from traditional starch extraction methods due to their environmental impact and low efficiency. The study aimed to optimize the ultrasound-assisted extraction process of starch from the cotyledons of mango seeds, employing response surface methodology with a customized optimal design and an optimal-I optimality criterion. We investigated the effects of cotyledon/water ratio, time, power, and sonication frequency on maximizing starch extraction yield. We explored the impact of ultrasound on structural, morphological, functional, and pasting properties. The maximum starch extraction yield was 50.74%. This yield was about 82.4% higher than that of conventional wet extraction. Ultrasound-assisted extraction increased starch purity and amylose content; it reduced granule size while enhancing all starch pasting properties without affecting starch's chemical structure and morphological, thermal, and functional properties. The mango cotyledon starch can be classified as medium to normal amylose content starches, exhibiting A-type polymorphs, fast-swelling, and capable of forming strong, firm, low-sticky gels. These results demonstrate the potential applications of mango residue and ultrasound technology in the food and pharmaceutical industry.

Influence of Elevated Potassium Fertilization on Structural and Functional Properties of Sweet Potato Root Tuber Starch

Nine sweet potato varieties with different flesh colors were cultivated under uniform environmental conditions with potassium (K) fertilizer treatments at levels of 0, 22.5, and 45 kg/ha. The structural and functional properties of the starches were subsequently analyzed. The soluble sugar content in the dry root tuber increased, with higher K levels in most varieties. Amylose content decreased in Sushu16 but increased in Ningzishu1, with no significant differences observed in other varieties across different K levels. Elevated K levels had no effect on starch protein content, crystalline type, or gelatinization enthalpy. The impact of K fertilizer on starch thermal and pasting properties varied among the varieties. PLSR and PLS-DA analyses revealed that genotype background was the primary factor influencing starch properties. This research will provide a reference for the improvement of sweet potato production quality and efficiency and a scientific basis for the cultivation and utilization of sweet potato root tubers.

Glutinous rice gel as all-natural ink supply for extrusion-based food 3D printing – the chemical basis of gel printability

In this study, four varieties of glutinous rice were screened out of 18 varieties as representative model inks. Gel prepared using variety WN9612 of high amylose content displayed high viscosity and large overall print deviation (OPD = 17.4 ± 0.4 %) due to difficulties in extrusion. Printed item by variety 19,415 of medium amylose content showed good printability (OPD = 4.4 ± 0.4 %) and highest hardness (197.5 ± 7.3 N). Similarly good printability was demonstrated by variety 19,416 (OPD = 4.1 ± 0.2 %) containing low amylose content but abundant protein and bound-water. Variety WN9446 lacking protein and moisture created item with fluid structure, lowest gel strength (738.5 ± 20.9 Pa) and standing ability. Therefore, low to medium amylose content rendered suitable viscosity, extrudability and printability of rice gel while non-starchy components predominated water mobility and texture of 3D printed items. This study for the first time establishes theoretical groundwork of selecting glutinous rice varieties with appropriate chemical composition as all-natural materials in 3D printing and food customization.

The properties of potato starch with different moisture content treated by cold plasma:Structure, physicochemical and digestive properties

To investigate the effect and mechanism of water on the structure, physicochemical properties, and in vitro digestibility of starch treated with CP, different moisture content (16.7 %, 28.6 %, 37.5 %, 44.4 %, and 50 %, w/w) were used, followed by treatment with CP (40 V, 1 A, 3 mins). Results show that CP treatment preserves the Maltese cross pattern, crystal morphology, and Fourier transform infrared spectroscopy spectra of potato starch. However, significant changes were observed in molecular weight, chain length distribution, average particle size, ordered structure, and relative crystallinity. As moisture content increased, the etching effect on the particle surface intensified, leading to further reductions in molecular weight and ordered structure. Concurrently, amylose content, solubility, relative crystallinity, and resistant starch content increased. At higher water levels, water molecules exhibited protective effects, mitigating CP-induced structural damage by reducing etching and loss of molecular weight. These findings suggest that the role of water in CP treatment is complex and provide insights into the interaction between CP and water in starch properties, highlighting its potential applications in starch-based foods.

Mechanism of starch multi-scale structural in determining the textural properties and formability of starch pearls

Starch pearls are widely used in bubble tea and desserts, yet the mechanistic understanding of the formation process of their textural properties remain unclear. To investigate the relationship between the multi-scale structure of starch and the textural properties of starch pearls, analyses of fine structure, crystal structure, rheological behavior, and textural profiling were conducted. The results showed that starch gels with a higher content of short-chain amylose (100 < X ≤ 1000) exhibited weaker formability during starch pearl preparation, leading to a lower flow behavior index (n*). This, in turn, positively influenced the hardness and resilience of the starch pearls. Cassava, potato, and yam starch pearls contained a large amount of long-chain amylopectin (24 < X ≤ 100) and long-chain amylose (5000 < X ≤ 20,000). The high proportion of long chains resulted in a weaker ordered structure, leading to increased peak viscosities and final viscosities and a higher consistency coefficient (k*). This structural feature enhanced the formability stability, viscosity, and chewability of starch pearls. Our findings reveal that variations in starch multi-scale structure significantly influence the textural quality and formability of starch pearls, providing valuable insights for optimizing starch selection and processing techniques in the food industry.

Modulating the assembly of starch-lecithin inclusion complexes and its underlying mechanism for controlling starch digestibility under the dense system

Starch-lipid inclusion complexes were used to regulate starch digestibility by changing the binding affinity of digestive enzymes such as α-amylase and α-glucosidase. However, when above a critical aggregation concentration (CAC) of starch and lipid molecules, they tended to self-assemble into double helices or normal micelles respectively, rather than interacting with each other to form starch-lipid complexes. Thus, how to enhance the complexation efficiency under a dense system is the key approach for the improvement of starch bioaccessibility and nutritional function. Herein, based on the dimethyl sulfoxide (DMSO) reverse solvent method, the effect of water/DMSO ratios and starch chain structures on the interaction and assembly behaviors between starch and lecithin molecules in high concentrations were systematically investigated. The results revealed that water/DMSO in a ratio of 1.5:1 promoted the interactions between cavities of starch helices and long alkyl chains of lecithin molecules, with higher level of complexed lecithin content, relative crystallinity (RC), enthalpy (ΔH) (Tp＞100°C), ordered-aggregation structures and resistant starch (RS) content. In this kind of solvent, starch samples with higher content of amylose and longer chains (degree of polymerization (DP) of B2 chains and B3+ chains) is advantageous to the formation of VII-type inclusion starch-lecithin complexes, with a rise in RS from 14.17% to 43.64%. It provided an effective method to modulate starch digestibility under the dense system of starch and lecithin via modulating the water/DMSO ratios and starch fine structures and lay the foundation for the large-scale preparation and application of starch-lecithin complexes.

‘Dapum’, a Late-Maturing Rice Cultivar with Low Amylose Content in the Chungnam Plain Area, Korea

‘Dapum’, a Late-Maturing Rice Cultivar with Low Amylose Content in the Chungnam Plain Area, Korea

Nitrogen affects the grain quality and antioxidant response of super rice varieties of fragrant and non-fragrant genotypes under different planting methods

The fragrant genotype of super rice contributed to the high yield, superior quality and strong aroma in rice production. The different responses of super rice varieties of fragrant and non-fragrant genotypes to nitrogen fertilization and planting methods are still unclear. A two-year field experiment was conducted to investigate the effects of nitrogen fertilizer and planting methods on the head rice yield, quality, photosynthesis and biomass of fragrant (Yuxiangyouzhan) and non-fragrant (Jiyou615) genotypes of super rice. The results revealed that the head rice yield and grain quality of Yuxiangyouzhan were greater than those of Jiyou615. Increased nitrogen fertilization significantly improved the grain quality of both cultivars, with greater improvement in Jiyou615. Yuxiangyouzhan presented the highest head rice yield, milling quality, and protein content under HT, followed by under MD, and Jiyou615 presented the highest under MT and MD. Both cultivars had higher amylose content and lower alkali under MD. Grain quality differences were attributed to the effects of nitrogen and planting method on photosynthesis and biomass. Nitrogen fertilizer and planting method promoted increased biomass and rates of grain filling through enhanced photosynthesis, which ultimately led to improved head rice yield and milling quality and a harder texture in both cultivars. Additionally, N2 application increased the 2-AP content of YXYZ under MD, which may be related to the effects of antioxidant enzymes on proline content. Considering the cost, we concluded that 220 kg hm−2 of nitrogen fertilizer application under MD improved the quality and aroma of the fragrant genotype of super rice.

Effects of exogenous brassinosteroids on the starch structure, physicochemical properties and digestibility of wheat under high-temperature stress at the early grain-filling stage

The starch synthesis of wheat was seriously affected by high temperature stress, which affected its yield and quality. At the same time, plant hormones are often used to regulate crop production and mitigate environmental stress in times of adversity. However, whether Brassinosteroids (BRs) can alleviate the adverse effects of high-temperature stress on wheat starch and its internal mechanism are still unclear. Therefore, a two-year field experiment was carried out from 2020 to 2022 to explore the effects of exogenous BRs spraying on the wheat yield, morphological structure and physicochemical properties of starch under high-temperature stress at the early grain-filling stage. The results showed that exogenous spraying of BRs under high-temperature stress increased the activity of key enzymes involved in starch synthesis, the contents of amylose (25.34 %) and amylopectin (11.57 %) were increased on average in two years, and ultimately increased the yield. On the other hand, BRs increased the number of B-type (49.90 %) and C-type starch granules (23.19 %), decreased the number of A-type starch granules (6.38 %) under high-temperature stress, and reduced the chain length of B1 (5.04 %) and B2 (4.88 %) chains of amylopectin. Moreover, BRs decreased crystallinity (25.40 %), gelatinization enthalpy (4.76 %) and 1047/1022 cm−1 (1.25 %), thereby improving the cooking quality of the starch. Through further analysis of the rheological properties and digestibility of starch, BRs improved the processing quality of starch and increased the content of resistant starch (RS, 15.77 %), which provided insights for the processing and utilization of food. In summary, under high-temperature stress, exogenous BRs increased wheat yield and improved starch quality. We recommend BRs as an effective management measure to mitigate high-temperature stress to cope with future climate change.

Modifying the Resistant Starch Content and the Retrogradation Characteristics of Potato Starch Through High-Dose Gamma Irradiation

Potato starch is widely utilized in the food industry. Gamma irradiation is a cost-effective and environmentally friendly method for starch modification. Nevertheless, there is a scarcity of comprehensive and consistent knowledge regarding the physicochemical characteristics of high-dose gamma-irradiated potato starch, retrogradation properties in particular. In this study, potato starch was exposed to gamma rays at doses of 0, 30, 60, 90, and 120 kGy. Various physicochemical properties, including retrogradation characteristics, were investigated. Generally, the apparent amylose content (AAC), water absorption, gel viscosity, gel hardness, and gumminess decreased as the doses of gamma irradiation increased. Conversely, the resistant starch (RS), amylose content evaluated by the concanavalin A precipitation method, water solubility, and enthalpy of gelatinization were increased. Additionally, swelling power, crystalline structure, and amylopectin branch chain length distribution either remained stable or exhibited only minor changes. Notably, the degree of retrogradation of potato starches on day 7 was positively correlated with the doses of gamma irradiation.

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.

Starch modification by low-dose electron beam irradiation: A comprehensive study between buckwheat starch, potato starch and pea starch

Electron Beam Irradiation (EBI) is an emerging technique for food decontamination and starch modification, but a comprehensive evaluation at safe doses (<10 kGy) for different starch sources is lacking. This study investigated the effects of low-dose EBI (2–8 kGy) on the physicochemical properties of buckwheat starch (BS), potato starch (POS), and pea starch (PS), each with different crystalline types (A-, B-, and C-type, respectively). EBI significantly reduced moisture and amylose content, decreased pasting viscosity, and retarded retrogradation dose-dependently for all starches. It also altered relative crystallinity (RC), thermal properties, rheological properties, and in vitro digestion, with effects varying by starch source. EBI-treated BS and POS showed decreased RC, gelatinization temperature and enthalpy, and increased paste flowability, while EBI-treated PS exhibited the opposite trend. Digestibility of EBI-treated BS initially decreased then increased with dose, while POS digestibility increased, and PS digestibility remained unchanged. This study highlights the versatility of EBI in starch modification, emphasizing its potential in developing low-viscosity starchy foods.

Thermo-reversible gel synthesized by 4-α-glucanotransferase with sol-gel transition tuned by subtle amylose manipulation

Thermo-reversible gels have garnered significant interest in food, pharmaceutical, cosmetic, and therapeutic delivery sectors. The increasing demand for plant-based ingredients has further propelled research into plant-derived gels. This study investigates the application of 4-α-glucanotransferase from Thermus thermophilus STB20 (Tt4αGT) to synthesize thermo-reversible gels from seven starches. Detailed rheological analyses and fine structural characterizations were conducted to elucidate the mechanisms underpinning gel formation. The results indicate that amylose content and amylopectin chain length distribution are pivotal factors; specifically, an amylose content exceeding 5% is essential for gel formation was proposed for the first time. Modified starches exhibited a higher proportion of both short (DP 6–8) and long chains (DP > 26) compared to their native counterparts. Rheological assessments demonstrated that these gels maintained thermal stability through repeated heating and cooling cycles between 90 °C and 4 °C. Notably, Tt4αGT treatment significantly enhanced gel strength, particularly in tapioca starch (TS), and improved the thickening performance and reversibility of starch. The gel network structure was primarily stabilized by hydrogen bonds, supplemented by electrostatic interactions. These findings highlight the potential of Tt4αGT-treated starches as versatile materials for various industrial applications.

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.

Effect of ultrasonic treatment on the structure and functional properties of protein-fortified potato powder

Potato powder has substantial nutritional value and gluten-free protein, making it an ideal ingredient in gluten-free foods that meet the dietary requirements of individuals with gluten allergies. However, the absence of gluten protein limits the processing and utilization of potato powder-based products. Different levels of power density (1–5 W/cm3) was used on potato powder enriched with whey protein and determine the impact of structural and functional characteristics by CLSM, FTIR spectroscopy, X-ray diffraction, low-field nuclear magnetic resonance and thermogravimetric analyses. The results showed that ultrasonic treatment destroyed the structures of starch and protein in protein-fortified potato powder, resulting in smaller starch granules. Compared with the blank group, the amylose content increased by 0.13-fold, relative crystallinity (RC) increased to 15.9%, water absorption capacity increased by 36% and oil absorption capacity increased by 112.5%. Ultrasonic treatment increased the contents of disulfide bonds, α-helices and β-sheets in protein-enhanced potato powder; improved the strength and construction rate of the protein network structure; promote the transformation of immobilized-water to bound-water and reduce the water mobility of dough and increased the hardness of protein-enhanced potato powder gel by 1.5-fold. In contrast, excessive ultrasonic power had a negative effect while consuming energy.

Creating of novel Wx allelic variations significantly altering Wx expression and rice eating and cooking quality

Granule-bound starch synthase I (GBSSI) encoding gene Waxy (Wx), which largely regulates the amylose content of rice grains, is a master module determining rice eating and cooking quality (ECQ). Fine-tuning amylose level of grains is an ideal strategy to improve rice quality. Through fine editing of Wxa promoter and 5′UTR by CRISPR/Cas9 system, we created 14 types of novel Wx allelic variations, of which MT7 and MT13 were able to alter Wx expression and amylose content of grains. MT7 showed fragment deletion and base insertions in CAAT-boxes, hardly detectable expression levels of GBSSI mRNA and protein, and generated 5.87% amylose in grains. MT13 had fragment deletions in the A-box and the TATA-box, low expression levels of GBSSI mRNA and protein, and generated 9.61% amylose in grains. Besides of the amylose content, MT7 and MT13 significantly reduced protein content and increased lipid content of grains compared with Wxa. A comparison of MT7, MT13 and other allelic lines demonstrated the importance of base insertion around the second CAAT-box and 31bp-deletion following the second TATA-box in modulating Wx expression. Thus, our study generated two novel Wx allelic variations which significantly alter Wx expression and amylose content of rice grains, providing not only new germplasms for soft rice breeding, but also insights into candidate cis elements of Wx.

Enhancing 3D printing accuracy of cassava starch gel through temperature-controlled freezing

Starch is an important renewable resource, however, the performance of 3D printing inks prepared from it requires improvement. This study revealed the effects of different freezing temperatures (25 °C, 4 °C, 0 °C, −20 °C, −40 °C, −80 °C) on the 3D printing accuracy of cassava starch (CS) gels in terms of starch gel properties (rheological properties, moisture distribution, submicroscopic structure) and multiscale structure (molecular size, chain length distribution, short-range ordered structure). As the freezing temperature decreased, the molecular size and the amylose (Am) content in CS gel were increased, particularly for short Am chains (X∼100–1000). These resulted in a greater orderly structure of the starch, enhancing the elastic modulus of the gel. Moreover, the lower the freezing temperature, the higher mobility of water molecules within the gel matrix after thawed, which in turn caused the reduction of gel viscosity and facilitated the smooth squeezing of the gel. After freeze-thawing at cryogenic temperatures, the above changes in CS gel properties improved the stiffness and support performance of the gel structure, thereby enhancing the 3D printing precision. This study provides insights into the development of 3D printing technology for starchy food materials, emphasizing its potential to transform the customization of starch-based food processing by enabling customized food products, enhancing texture, and offering consumers personalized food choices and improved sensory experiences.

Elucidating the impact of dual modification with hydroxypropylation and enzymatic hydrolysis on physicochemical properties of corn and sago starch

Enzymatic hydrolysis is one of the most commonly used techniques in starch modification. However, the performance of enzymatic hydrolysis has been restricted by the inherent properties of native starch. In this study, hydroxypropylation with two different concentration levels of propylene oxide (10% and 20%) was carried out on corn and sago starches. The effect of hydroxypropylation on the physico-chemical properties of the enzyme-hydrolyzed starch was investigated. The results showed that the starches treated with 20% propylene oxide had higher molar substitution and dextrose equivalent with greater effects. Scanning electron microscope (SEM) revealed that hydoxypropylation had developed pores and pits on the granular surfaces and subsequently enhanced enzyme penetration. Hydroxypropylation showed no changes in the crystalline pattern, yet a decrease in the amylose content of both corn and sago starches, respectively. Other than that, hydroxypropylation decreased the pasting properties and retrogradation tendency but increased the swelling power of enzymehydrolyzed starch significantly. Overall, this work suggested that hydoxypropylation pretreatment could improve the efficiency of subsequent enzyme hydrolysis and produce modified starch with great potential in food processing applications.

Heat-treated brown rice starch structure and effect on short-chain fatty acids and mouse intestinal microbiota

Rice with high resistant starch (RS) exhibits the potential to improve glucose metabolism, insulin sensitivity. In this study, using two rice varieties—Samgwang, a medium-amylose rice, and Dodamssal, a high-amylose rice containing RS—we analyzed the composition and molecular structural characteristics of brown rice and its starch and the effects on fasting blood glucose levels, fecal short-chain fatty acid (SCFA), and gut microbiota after 8 weeks of consumption in mice. The amylose content of heat-treated Samgwang (HS) and -Dodamssal (HD) was 21.0 ± 0.2 and 47.5 ± 0.3 %, respectively, while RS contents were 0.8 ± 0.0 and 14.7 ± 1.0 %. HD exhibited a C-type starch crystallinity with a lower proportion of short chains and a higher proportion of long chains compared to HS. HD-fed mice exhibited lower fasting blood glucose levels and the highest SCFA levels in their feces. They also had the highest abundance of Ruminococcus bromii, an RS-degrading bacterium, the highest positive correlation with Faecalicatena fissicatena (r = 0.9), and the highest negative correlation with Lachnoclostridium scindens and Lawsonibacter asaccharolyticus (r = −0.8). Overall, HD consumption can improve glucose metabolism by increasing intestinal SCFA production and can serve as a prebiotic dietary ingredient to improve obesity and diabetes.