Digestibility Of Rice Starch Research Articles

Microwave Assisted Cooking Improves Edible Quality of Germ Rice: Insights of Multiscale Starch Microstructure, In Vitro Digestion, and Flavor

AbstractGerm rice is a moderately processed products with high germ retention rate (>80%). Electric rice‐cooker and microwave cooking as the most common cooking methods have different effects on starch microstructures, digestibility, rheological behavior, texture, and flavor of germ rice. Microwave‐cooked germ rice contains more short‐range ordered structures and higher crystallinity than electric rice‐cooker cooked germ rice. The starch digestibility of germ rice (i.e., rapidly digestible starch) cooked by microwave under different power and time (50.74%–52.47%) is lower than that of electric rice‐cooker cooked by two modes (60.52%–60.82%). The rheology (modulus and shear viscosity) of germ rice treated by electric rice‐cooker is higher than that treated by microwave. Microwave‐cooked germ rice has lower adhesiveness (164–212 g s) than that cooked in electric rice‐cooker (286–295 g s). Aldehydes are the most abundant volatile components, and play a very important role in germ rice flavor. Microwave cooking can reduce the digestibility of starch and improve the flavor of cooked germ rice. Microwave is expected to be a promising cooking technique for germ rice cooking.

The structural characteristics and in vitro starch digestibility of rice noodles as affected by the addition of ultrafine whole pulp of bamboo shoots

Rice noodles are a high-carbohydrate food. Thus, the aim of this study is to evaluate the effect of different additions (CK (0%), 13%, 16%, 19%, and 21% w/w) Chimonobambusa quadrangularis ultrafine whole pulp (CQUWP) on rice noodles by in vitro digestion simulation and quality characterization. The results indicated that among the textural properties, the cooking characteristics, water absorption, and hardness of rice noodles were improved with the addition of an appropriate amount of CQUWP (13%). The predicted glycemic index (pGI) of 21% rice noodles was reduced by 25.28% compared with CK, and the elasticity and viscosity of starch gels (G′ and G″) increased with the increase of loss tangent (Tanδ). Finally, the sensory evaluation and principal component analysis (PCA) indicated that the addition of 13% rice noodles results in better flavor. Furthermore, this study aims to provide a theoretical basis for the subsequent development of bamboo shoot rice noodles.

Reducing starch digestibility of white rice by structuring with hydrocolloids

Controlling starch digestion in high glycaemic index staple foods such as white rice is of interest as it has been associated with reduced risk for conditions such as obesity and type-2 diabetes mellitus. Addition of hydrocolloids has been proposed to reduce the rate of post-prandial glucose by controlling the rate of starch hydrolysis. In this work, the potential of a range of hydrocolloids to modify starch digestibility when added (at 1 % maximum concentration) during cooking of white rice was first investigated. Low acyl gellan gum (LAG) showed the highest potential (in-vitro estimated Glycaemic Index reduced by about 20 %, from 94 in the control to 78 in the LAG rice) and was investigated further. While the grains of rice control and rice with LAG appeared similar, SEM images revealed a gel-like layer (a few micrometers in thickness) on the surface of the treated samples. Addition of LAG appeared to also have an effect on the breakdown of a simulated cm-sized bolus. During gastric digestion, bolus breakdown of the rice control was completed after 30 min, while the rice LAG bolus appeared intact after 1 h of observation. This was attributed to strengthening of the LAG gel in the acidic environment of the stomach. During intestinal digestion, rice samples containing 1 % LAG appeared to be less susceptible to breakdown when seen under a microscope and in environmental SEM, while they showed larger rice particle aggregates, compared to rice control. Overall, LAG showed potential to control starch digestion kinetics of white rice with a mechanism that may involve formation of a protective layer on the rice grains (um) that reduces bolus break down (cm) and enzymatic hydrolysis (nm). Outcomes of this work will be used to identify conditions for further relevant in-vitro and in-vivo investigations.

Quantitative prediction of rice starch digestibility using Raman spectroscopy and multivariate calibration analysis

Digestibility is an important characteristic of rice starch. It is affected by the growing environment, such as temperature and soil, so that even in the same genetic cultivar the digestibility of each product will be different. Here, we predicted rice starch digestibility by Raman scattering spectroscopy. A partial least squares (PLS) regression analysis was performed between biochemically quantified digestibility index values and Raman scattering spectra of purified starch from rice samples of different cultivars and growing conditions. The prediction model obtained by analyzing the individual cultivars was able to predict digestibility with a high accuracy, with an R2 of 0.95 and RMSEP of 0.43, whereas a mixture of all cultivars resulted in more than two times worse accuracy. Our finding suggests that the molecular structures affecting digestibility fluctuate depending on the growing environment while maintaining a unique balance regulated by cultivar-specific starch synthesis mechanisms.

Controlling the digestibility and multi-level structure of waxy rice starch by complexation with Artemisia sphaerocephala Kracsh Gum

In this study, the effects of various concentrations of Artemisia sphaerocephala Krasch gum (ASKG) on the digestibility and multi-level structure of waxy rice starch (WRS) were evaluated, and mechanism on controlling the digestibility from structural evolutions was revealed. Results showed that ASKG addition decreased the rapidly digestible starch (RDS) levels of WRS from 54.9% to 32.9%. Regarding the structural changes, it can be observed that ASKG addition effectively increased the values of gelatinization enthalpy (ΔH), short-range ordered degree (R1047/1024), relative crystallinity (RC), compactness (α), and microphase heterogeneity (ε) of WRS, indicating the formation of more ordered molecular structure, crystalline structure, nano-aggregated structure. Furthermore, after the addition of ASKG, starch-ASKG complexes presented tighter network structure with thicker layer wall and more uniform pores. And these structural alterations may contribute to reduce the digestion rate and extent of WRS. Hence, it can be concluded that digestibility of starch could be tailored by modulating its hierarchical structure through hydrocolloid addition.

Understanding starch digestibility of rice: a study in white rice

SummaryIn vitro starch digestibility, chemical, pasting, and gelatinisation properties of 10 uncooked pigmented and non‐pigmented Thai white rice were studied. Differing in amylose and starch contents, the samples were also significantly (P ≤ 0.05) different in pasting and gelatinisation properties, maximum digestible starch (40–53 g/100 g dry starch), and rate of starch digestion (0.028–0.054 min−1). The starch digestograms were adequately described (r2 > 0.63; P ≤ 0.001) by objective logarithm of slope (Sopade Objective Procedure), modified first‐order kinetic, and two‐term exponential and non‐exponential models to be all truly monophasic. The estimated glycaemic index (g/100 g) ranged from 64 and 84, compared to 41–95 for their brown rice forms (International Journal of Food Science and Technology, 2022, 57, 6699), highlighting how bran and hull components influence starch digestion of polished and non‐polished rice. This study is foundational to detailedly understand starch digestibility when the rice is further treated.

Effect of processing conditions on the functional properties of starches during formulation of quick-cooking brown rice

The demand for ready-to-cook and nutritious products is on the rise due to the lifestyle becoming more hectic throughout the world. In this study, quick-cooking brown rice was formulated from four rice varieties. For each variety, the process was optimized by analyzing different combinations of soaking time (10, 20, and 30 min), drying time (20, 30, and 40 min), and drying temperature (60, 70, and 80 °C). Central composite design (CCD) was used to select the best combinations based on the least cooking time and moisture content within the range of 12–14%, and the same was different for each rice variety. To comprehend the effect of these processing conditions on rice, its main constituent i.e. starch, known to affect the palatability of rice cultivars was investigated. The starches were extracted from all the four quick-cooking brown rice samples and their properties were compared with respective native starches. Results obtained indicated that the treated starch samples from all varieties had better solubility and swelling behaviors. Treated starches also demonstrated higher retrogradation as compared to native starches. Untreated starches showed a well-defined polygonal structure of starch granules while treated starches showed distorted structures under scanning electron microscopy indicating their partial gelatinization. X-ray diffraction results indicated that in all the varieties of rice A-type starch was present, however, upon treatment diffraction peaks changed for all the varieties and the typical A-type structure of untreated starch shifted to CA-type starch structure. Readily digestible starches (RDS%) of all the treated starches increased while slowly digestible starches (SDS%) of all the treated starches decreased. Results indicated that both soaking time, drying time and drying temperature had significant effect on the physicochemical properties and digestibility of rice starches.

Using mid‐infrared spectroscopy combined with chemometrics to determine digested starch and maltose concentration during in‐vitro digestion of starches

SummaryStarch digestion is typically evaluated using in‐vitro techniques. During and after the in‐vitro digestion, samples are collected (gastric and intestinal phases) at allotted time intervals where starch digestion is quantified through the analysis of sugars using routine chemical and enzymatic analysis. This paper reports the use of mid‐infrared (MIR) spectroscopy as rapid method to measure the concentration of maltose and % digested starch during the digestion of rice and potato starch, maize starch namely Gelose 50 (50% amylose), Gelose 80 (80% amylose) and pregelatinized corn starch collected at different time points (5, 10, 15, 20, 25, 30, 40, 50, 60, 75, 90, 105 and 120 min) from two in‐vitro digestion experiments. Two types of samples, turbid and supernatant were also evaluated. The coefficient of determination (R2) and the standard error in cross‐validation (SECV) ranged between 0.74 to 0.93 and 163 to 360 μg mL−1 for the prediction of the concentration of maltose. The use of turbid samples showed a better predictive ability when compared with the regression models developed using the supernatant samples. This method showed potential to significantly decrease the time and effort associated to determining maltose concentration and % digested starch during in‐vitro digestion.

Antioxidants and in vitro starch digestibility of coloured rice, and its effect on blood sugar and malonaldehyde in streptozotocin-nicotinamide-induced diabetic rats

Diabetes mellitus (DM) is an autoimmune disease caused by abnormal regulation of blood sugar, with type 2 DM representing 90 - 95% of total DM incidence. One of the preventive measures to improve blood sugar control is the regulation of eating patterns. The purposes of the present work were therefore (1) to determine the proximate composition, carotene and anthocyanin contents, starch digestibility, and antioxidant capacity of Baturraden white rice, Baturraden organic brown rice, and Sirampog black rice; and (2) to determine the effect of feeding these rice on fasting blood sugar and malondialdehyde (MDA) production in diabetic rats. Sirampog black rice had higher levels of carotene and anthocyanin, and higher radical scavenging activity than Baturraden organic brown and white rice. In diabetic rats, Sirampog black rice (Δ = 153.80 mg/dL) could reduce fasting blood sugar more effectively than Baturraden organic brown rice (Δ = 124.48 mg/dL) and Baturraden white rice (Δ = 14.62 mg/dL). Diabetic rats treated with Sirampog black rice also presented the lowest MDA levels of 2.62 nmol/mL when compared with that of Baturraden organic brown rice (3.96 nmol/mL) and Baturraden white rice (10.14 nmol/mL). Based on these results, patients with DM are advised to consume Sirampog black rice. In the future, it is necessary to perform trials in patients with DM to determine the effect of Sirampog black rice on fasting blood sugar and diabetic weight loss.

Influence of instant rice characteristics and processing conditions on starch digestibility-A review.

Instant rice is increasingly popular around the world due to its convenience, but it commonly has a high glycemic index, and a frequent consumption might contribute to the occurrence of many chronic diseases. In this review, the main factors determining starch digestibility of instant rice were comprehensively evaluated, aiming to help the rice industry develop instant rice with slow starch digestibility. Starch digestibility in instant rice can be reduced by manipulating its intrinsic and extrinsic nutrients. Processing conditions, including pre-gelatinization, storage, and reheating are also important for the starch digestibility of instant rice. Individual differences in terms of glycemic response to the same carbohydrate-based diet should be considered when knowledge is transformed from in vitro method to human conditions. This review contains important information that has the potential to reduce the starch digestibility of instant rice and improve public health.

Structures and digestibility of B-type high-amylose rice starches compared with A-type high-amylose rice starches

The starch structures and digestibility of starches prepared from newly developed Korean high amylose rice varieties were investigated. Amylose (AM) contents of Goami, Shingil, Goami 2, and Dodam starches were 25.56, 30.34, 36.33, and 45.78%, respectively. The Goami and Shingil starches were A-type crystallinity, while the Goami 2 and Dodam starches were B-type crystallinity. The molecular weights of AM were lower in the B-type starches (1.64 × 105 and 1.88 × 105) than in the A-type starches (3.88 × 105 and 3.00 × 105). The average chain length (CL) and longer branch CL (DP ≥ 25) of amylopectin (AP) were higher in B-type rice starches than in A-type rice starches. The ratio of 1045/1022 cm-1 and relative crystallinity were lower in the B-type rice starches. These results show that B-type starches have a higher AM content (>35%), gelatinization temperature, resistance to digestibility, and longer branch CL of AP, but a lower AM molecular weight than A-type starches.

Extrusion assisted interaction of rice starch with rice protein and fibre: Effect on physicochemical, thermal and in-vitro digestibility characteristics

Rice starch has high digestibility due to its large carbohydrate content. Macromolecular enrichment of starch has the tendency to retard rate of starch hydrolysis. Hence, the current investigation was aimed to check the combined effect of extrusion assisted addition of rice protein (0, 10, 15 and 20 %) and fibre (0, 4, 8 and 12 %) to rice starch on physico-chemical and in-vitro digestibility characteristics of starch extrudates. It was observed from the study that ‘a’ and ‘b’ values, pasting temperature and resistant starch of starch blends and extrudates increased with the addition of protein and fibre. However, lightness value, swelling index, pasting properties and relative crystallinity of blends and extrudates decreased with the addition of protein and fibre. Maximum increase in thermal transition temperatures was observed for ESP3F3 extrudates due to absorption capacity of protein molecules which led to late onset of gelatinization. Therefore, enrichment of protein and fibre to rice starch during extrusion can be considered as a novel approach to reduce rate of rice starch digestion for catering nutritional requirements of diabetic population.

Purple red rice bran anthocyanins reduce the digestibility of rice starch by forming V-type inclusion complexes

Purple red rice bran, a by-product of the rice polishing process, contained abundant anthocyanins. However, most of them were discarded resulting in a waste of resources. This study investigated the effects of purple red rice bran anthocyanin extracts (PRRBAE) on the physicochemical properties and digestive properties of rice starch and its mechanism of action. Infrared spectroscopy and X-ray diffraction indicated that PRRBAE could interact with rice starch through non-covalent bonds to form intrahelical V-type complexes. The DPPH and ABTS+ assays showed that PRRBAE could confer better antioxidant activity on rice starch. In addition, the PRRBAE could increase the resistant starch content and decrease the enzyme activities by changing the tertiary and secondary structure of starch-digesting enzymes. Further, molecular docking suggested that aromatic amino acids play a key role in the interaction of starch-digesting enzymes with PRRBAE. These findings will contribute to a better understanding of the mechanism of PRRBAE reducing starch digestibility, and to the development of high value-added products and low glycemic index (GI) foods.

Effect of starch-protein interaction on regulating the digestibility of waxy rice starch under radio frequency treatment with added CaCl2

This study investigated the effect of starch-protein interaction on regulating the digestibility of waxy rice starch under radio frequency (RF) treatment with added salts. The results showed that starch-protein interactions could significantly reduce the digestibility of waxy rice starch (WRS) under synergetic Ca2+-RF treatment. With the increase of Ca2+ content (0–2 %), the resistant starch content of WRS-WPI, WRS-SPI and WRS-PPI increased from 35.53 %, 36.12 % and 38.78 % to 51.05 %, 52.82 % and 55.93 %, respectively. The addition of appropriate Ca2+ content could increase the short-range ordered structure and lamella structure and form a more compact and uniform microstructure. In addition, the interaction between WRS and protein was mainly through hydrogen bonding and hydrophobic interactions during RF treatment. Furthermore, the presence of Ca2+ could improve the distribution and mobility of water molecules and regulate the rheological properties of WRS-protein complexes. This study offers theoretical guidance for the design and production of rice starch-based products with lower digestibility.

Structure, thermal stability, and in vitro digestibility of rice starch–protein hydrolysate complexes prepared using different hydrothermal treatments

In this study, rice starch-protein hydrolysate (WPH-S) complexes with high resistant starch (RS) content were prepared by heat-moisture treatment (HMT) and annealing (ANN). The effects of different hydrothermal treatments on the structure and thermal stability of the WPH-S complexes and their relationship with starch digestibility were further discussed. The results showed that RS contents of ANN-WPH-S complexes (35.09–40.26 g/100 g) were higher than that of HMT-WPH-S complexes (24.15–38.74 g/100 g). Under hydrothermal treatments, WPH decreased the hydrolysis kinetic constant (k) of starch form 4.07 × 10−2–4.63 × 10−2 min−1 to 3.29 × 10−2–3.67 × 10−2 min−1. HMT and ANN promoted hydrogen bonding between WPH and starch molecules, thus increasing the molecular size of starch. In addition, the shear stability of WPH-S mixture was improved with the hysteresis loop area decreased after HMT/ANN treatments, resulting in a more stable structure. Most importantly, the hydrothermal treatment made the scatterers of WPH-S complexes denser and the surface smoother. Especially after ANN treatment, the WPH60-S complex formed a denser aggregate structure, which hindered the in vitro digestion of starch to a certain extent. These results enrich our understanding of the regulation of starch digestion by protein hydrolysates under different hydrothermal treatments and have guiding significance for the development of foods with a low glycemic index.

Effects of storage temperatures on the starch digestibility of whole rice with distinct starch fine molecular structure.

Although the retrogradation of rice starch has been extensively investigated, there remain questions as to how storage temperature affects starch inter- and intramolecular interactions in cooked white rice, and the relationship of these interactions with the digestion rate. To this end, micromorphology, crystallinity polymorphisms, molecular interaction patterns and in vitro starch digestibility of 3 rice varieties kept under 5 different storage temperature programs (room temperature (RT), 4 °C, -18 °C, 4 °C/RT (4 °C for 24 h and then RT for 24 h), -18 °C/RT (-18 °C for 24 h and then RT for 24 h)) were investigated. As expected, a significant variance in starch digestibility was observed for samples after storage at different temperatures. Overall, storage at 4 °C could most effectively decrease the starch digestibility of retrograded rice. The digestion rate constant was for the first time found to be determined by short-range amylopectin intermolecular interactions rather than long-range starch molecular interactions, for all different storage conditions. Furthermore, the digestion extent was determined by both inter- and intramolecular interactions among starch molecules as well as by the long-range order of the retrograded double helices. These results could prove useful to devise storage regimes which use retrogradation to produce cooked rice with lower glycemic index.

The Effects of Starch Molecular Fine Structure on Thermal and Digestion Properties of Rice Starch.

Whole white rice is a major staple food for human consumption, with its starch digestion rate and location in the gastrointestinal tract having a critical role for human health. Starch has a multi-scale structure, which undergoes order-disorder transitions during rice cooking, and this structure is a major determinant of its digestibility. The length distributions of amylose and amylopectin chains are important determinants of rice starch gelatinization properties. Starch chain-length and molecular-size distributions are important determinants of nucleation and crystal growth rates, as well as of intra- and intermolecular interactions during retrogradation. A number of first-order kinetics models have been developed to fit starch digestograms, producing new information on the structural basis for starch digestive characteristics of cooked whole rice. Different starch digestible fractions with distinct digestion patterns have been found for the digestion of rice starch in fully gelatinized and retrograded states, the digestion kinetics of which are largely determined by starch fine molecular structures. Current insights and future directions to better understand digestibility of starch in whole cooked rice are summarized, pointing to ways of developing whole rice into a healthier food by way of having slower starch digestibility.

Thermodynamic, Thermal, Structural Properties and In Vitro Digestibility of Basmati Rice Starch Subjected to α‐Amylase

AbstractThe objective of this work is to evaluate the effect of drying temperature combined with enzymatic modification with α‐amylase on the in vitro digestibility, thermodynamic, thermal and structural properties of Basmati rice starch. The basmati rice starch is dried at drying temperatures (40, 45, 50, 55, and 60 °C), during the process thermodynamic properties such as enthalpy, entropy, and Gibbs free energy are analyzed. After drying, the raw starches are treated with α‐amylase (3 U mg−1) and analyzed by X‐ray diffraction and differential scanning calorimeter. The process is considered as endothermic and endergonic, where the temperature of 60 °C promotes a 22% reduction in the drying time and a higher hydrolysis yield (4.02%). The crystallinity index and the enthalpy of gelatinization are reduced according to the drying temperature and the type A crystallinity is not modified. This study shows that the drying temperature influences enzymatic susceptibility, with 60 °C being the most suitable temperature.

Structure, gelatinization, and digestion characteristics of starch from Chinese wild rice

ABSTRACT Two wild rice starches were isolated from Erhai in Dali, Yunnan Province (EWR) and Xinghua in Taizhou, Jiangsu Province (XWR), China, and compared with black rice (BR) starches, its structure, gelatinization and starch digestibility in vitro were studied. The results showed that the apparent amylose content of starches in EWR and XWR was 19.82% and 20.33%, respectively. The starch granules were irregular polygons and all were A-type crystals, with relative crystallinity of 25.6%~26.65%, similar short-range ordered structure and layered structure, and the thickness of the semi-crystalline layer ranged from 9.82 nm to 9.97 nm. XWR and EWR starches had exhibited the same gelatinization temperature range, enthalpy of gelatinization (ΔHgel) and swelling power, but XWR starches was higher than EWR in the gelatinization temperature and lower than EWR in the solubility. The rapidly digestible starch (RDS) content of wild rice starches in the two regions was low, only 3.63% and 37.32%, whether it was raw starches or gelatinized starches. After gelatinization, the RDS and slowly digestible starch (SDS) content were significantly increased and the resistant starch (RS) content was decreased, but the RS content was still higher than the common grains. Therefore, the wild rice starches are more suitable for processing and producing resistant starch products. Extracting starch from Chinese wild rice can provide guidance and reference for its application in edible and non-edible products, and promote the development and utilization of Chinese wild rice. Abbreviations: EWR, wild rice from Erhai in Dali, Yunnan Province; XWR, wild rice from Xinghua in Taizhou, Jiangsu Province; RDS, rapidly digestible starch; SDS, slowly digestible starch; RS resistant starch; TS, total starch; To, onset temperature of gelatinization; Tp, peak temperature of gelatinization; Tc, conclusion temperature of gelatinization; ∆Hgel, enthalpy of gelatinization.

Mechanism of peptides from rice hydrolyzed proteins hindering starch digestion subjected to hydrothermal treatment

Clarifying the interactions between food components is critical in designing carbohydrate-based foods with low digestibility. To date, the hindering effect of starch-protein interactions on starch digestion has attracted extensive attention. In this study, rice proteins were further hydrolyzed, and rice peptides (RP) with different molecular weights were obtained by ultrafiltration. The effects and possible mechanisms of RP with different molecular weights on the structure, thermal properties, and in vitro digestibility of cooked rice starch were investigated. All peptides slowed the digestion of rice starch in a concentration-dependent manner. A concentration of 10% RP>10 decreased the rapidly digestible starch content from 68.02 to 45.90 g/100 g, and increased the resistant starch content from 17.54 to 36.54 g/100 g. The addition of RP improved the thermal stability of the starch and reduced the amount of leached amylose. Infrared analysis shows that strong hydrogen bonds formed between RP (especially RP>10) and starch during co-gelatinization. In addition, RP improved the compactness of aggregated structure and played an important role in hindering the enzymatic hydrolysis of starch. These results enrich the theory of starch-protein interactions and have important implications for the development of carbohydrate-based foods with low digestibility and protein functional foods.