Identifying genes for resistant starch, slowly digestible starch, and rapidly digestible starch in rice using genome-wide association studies.

In this study, optimum conditions to produce slowly digestible starch (SDS) and RS from rice starch were investigated as a function of pullulanase concentrations, storage temperature, and autoclaving‐cooling cycles. Then, the physicochemical properties of the rice starches obtained were compared with native rice starch. Response surface methodology (RSM) was used to evaluate the effects of independent variables, namely the enzyme (pullulanase) concentration (X1), storage temperature (X2), and autoclaving‐cooling cycle (X3) on the production of SDS and RS fraction. The optimum conditions for SDS and RS occurred in the treatment with application of pullulanase at 482 and 610 µL, and storage temperature at 36 and 63°C with autoclaving cycles of three times, respectively. SDS and RS obtained through optimum conditions showed higher amylose content and water solubility index as compared to native starch. While the SF and water absorption index were lower than native starch. The extent of hydrolysis α‐amylose decreased in the order cooked starch>SDS>RS>native starch. SDS and RS had lower RVA parameters (except pasting temperatures) than native starch.

The objective of this study was to investigate the effects of amylose (AM):amylopectin (AP) ratio, extrusion, storage duration, and enzyme supplementation on starch digestibility of corn. Three corn varieties with high (0.60; HA), medium (0.44; MA), and low (0.39; LA) AM:AP ratios, respectively, were selected from 74 corn samples to evaluate the in vitro and in vivo digestibility of starch. In Exp. 1, during wk 4 after extrusion, resistant starch (RS) content of the 3 selected corn varieties (LA, MA, and HA) increased (P < 0.05) each week and starch digestibility in vitro decreased as storage time increased (P < 0.05). The AM:AP ratio affected the formation of RS (P < 0.01). The RS content of the 3 corn varieties was ranked as LA < MA < HA in each week (P < 0.05). Correlation analysis showed that AM:AP ratio and storage duration were both positively correlated with RS content (P < 0.01). Furthermore, a significant quadratic relation was found between storage duration and RS content in each corn variety as well as storage duration and digestibility. Starch digestibility was negatively correlated with RS content (P < 0.001). In Exp. 2, digestion trials were performed on cannulated pigs with BW of 13.20 ± 0.94 kg. Extrusion increased ileal digestibility of GE and starch of either HA or LA compared with the enzyme-supplemented diets (P < 0.001). Enzyme supplementation did not improve ileal energy and starch digestibility. The ileal digestibility of starch and GE of LA varieties was greater than HA samples (P < 0.05). The results implied that AM:AP ratio and storage duration after extrusion may be important determinants of RS formation and digestibility of starch for corn. In addition, RS content could be an important indicator of digestibility of starch in extruded corn. Using a lower AM:AP ratio corn or reducing the storage duration of extruded corn would help to reduce the formation of RS and improve the starch bioavailability of corn for piglets.

This study determined the effect of micronization (high intensity infrared heating) on the concentrations of rapidly digestible starch (RDS), slowly digestible starch (SDS), and resistant starch (RS) in normal barley (NB), high-amylose barley (HAB), and waxy barley (WB). The gelatinized starch contents and the thermal properties of the micronized samples also were determined. Samples of each barley type were tempered to each of three moisture contents (approximately 17, 31, or 41%), and then each tempered sample was micronized to each of three surface temperatures (100, 120, or 140 degrees C). Micronized barley samples were substantially lower in RS and in SDS and, therefore, higher in RDS than corresponding unprocessed samples. In general, higher concentrations of RDS and of gelatinized starch were associated with higher initial moisture contents and higher surface temperatures. The lowest concentrations of RS were observed in micronized WB samples. Similar concentrations of RS were observed in corresponding NB and HAB samples. Micronization resulted in slight increases in the onset (To), peak (Tp), and completion (Tc) gelatinization temperatures and in substantial reductions in the gelatinization enthalpy (DeltaH), the latter reflecting the levels of gelatinized starch in micronized samples, particularly in samples micronized at higher moisture contents and to higher surface temperatures. Endothermic transitions were evident only in samples tempered to 17% moisture or 31% moisture (surface temperature of 100 degrees C only).

Sorghum can be utilized as raw material to produce resistant starch because of its high amylose content. Resistant starch is the starch that is resistant to gastric acid hydrolysis and it cannot be digested by pancreatic digestive enzymes, it cannot be absorbed in the human small intestine, but it can be fermented by intestinal microbial in the colon. This study aims to increase the levels of resistant starch in modified sorghum flour by lactic acid bacteria fermentation and autoclaving-cooling cycling. Parameters analyzed in this study were proximate analysis starch digestibility, amylose content, total starch, reducing sugar, RDS (rapidly digestible starch), SDS (slowly digestible starch), and resistant starch. The combination treatment of fermentation and 2 cycles of autoclaving-cooling (FAC-2S) is the best treatment because it was able to produce the highest resistant starch content (39.06% dw) and it increased resistant starch 8.1 fold when compared with control. Improvement the number of autoclaving-cooling cycles was applied will increase the resistant starch content and decrease the digestibility of modified sorghum flour. High amylose content in modified sorghum flour is useful in the formation of resistant starch.

The objective of this study is to investigate formation of slowly digestible starch (SDS) and resistant starch (RS) and change in physicochemical properties of sweet potato and yam starches under a combination of acid and heat–moisture treatments using three mild organic acids including acetic acid, lactic acid and citric acid and heating temperature at 110°C for 8 h. The results show that the SDS and RS in sweet potato starch significantly increased from 6.6 and 14.7% in native starch to 8.7–13.2% and 37.5–42.1% in acid and heat–moisture treated starches, respectively. Likewise, the SDS and RS in yam starch increased from 4.7 and 21.6% in native starch to 10.0–11.3% and 39.0–46.4% in the treated starches, respectively. The RS content in the acid and heat–moisture treated starches was also significantly higher than that of the heat–moisture treated starches without acid hydrolysis. Yam starch produced higher amount of RS under acid and heat–moisture treatment as compared to sweet potato starch at the same condition. Swelling power and viscosity of starches significantly decreased, whereas the solubility significantly increased after treatments. The citric acid had the most impact on RS formation and starch properties, followed by lactic acid and acetic acid. As a result, the combination of acid and heat–moisture treatment is a useful method to produce higher amount of resistant starch, which can be applied for functional foods.

Inhibition of Starch Digestion by Dallic Acid and Alkyl Gallates

ABSTRACTThe influence of amylose content, cooking, and storage on starch structure, thermal behaviors, pasting properties, and rapidly digestible starch (RDS), slowly digestible starch (SDS), and resistant starch (RS) in different commercial rice cultivars was investigated. Long grain rice with high‐amylose content had a higher gelatinization temperature and a lower gelatinization enthalpy than the other rice cultivars with intermediate amylose content (Arborio and Calrose) and waxy type (glutinous). The intensity ratio of 1047/1022 cm–1 determined by Fourier Transform Infrared (FT‐IR), which indicated the ordered structure in starch granules, was the highest in glutinous and the lowest in long grain. Results from Rapid ViscoAnalyser (RVA) showed that the rice cultivar with higher amylose content had lower peak viscosity and breakdown, but higher pasting temperature, setback, and final viscosity. The RDS content was 28.1, 38.6, 41.5, and 57.5% in long grain, Arborio, Calrose, and glutinous rice, respectively, which was inversely related to amylose content. However, the SDS and RS contents were positively correlated with amylose content. During storage of cooked rice, long grain showed a continuous increase in pasting viscosity, while glutinous exhibited the sharp cold‐water swelling peak. The retrogradation rate was greater in rice cultivars with high amylose content. The ratio of 1047/1022 cm–1 was substantially decreased by cooking and then increased during storage of cooked rice due to the crystalline structure, newly formed by retrogradation. Storage of cooked rice decreased RDS content and increased SDS content in all rice cultivars. However, no increase in RS content during storage was observed. The enthalpy for retrogradation and the intensity ratio 1047/1022 cm–1 during storage were correlated negatively with RDS and positively with SDS (P ≤ 0.01).

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.

Measurement and Characterization of Dietary Starches

Digestibility and physicochemical properties of rice (Oryza sativa L.) flours and starches differing in amylose content

In vitro Digestibility Profiles of Different Types of Resistant Starch With Bioactive Guest Inhibitors

SummaryInfluence of diverse botanical sources (wheat, maize, waxy maize, cassava, potato, rice or waxy rice) on in vitro native starch digestibility has been investigated. Physicochemical properties (chemical composition, particles size and shape, surface features) of starch granules were determined with a view to explaining digestibility differences between samples. Rapidly digestible starch (RDS), slowly digestible starch (SDS) and resistant starch (RS) contents were measured according to Englyst method. Potato starch was shown to be composed of large rounded granules having smooth surfaces, which explains its slow enzymatic breakdown. Potato starch displayed the highest RS (86%) content and the lowest RDS content (9.9%). Since RS positively influences health and SDS may result in cell, tissue and/or organ damages, potato starch is an ideal starch nutrient. Conversely, waxy rice starch was rich in amylopectin and displayed small diameters and angular shapes, which are both known to facilitate enzymatic starch hydrolysis. It exhibited a near‐zero RS content (0.9%) and a high RDS fraction (60%). According to this study, potato starch exhibited the best nutrient profile, followed up in this order by cassava, waxy maize, wheat, maize and waxy rice starches.

Effect of roasted pea flour/starch and encapsulated pea starch incorporation on the in vitro starch digestibility of pea breads

The effects of ultrasonic treatment on physicochemical properties and in vitro digestibility of semigelatinized high amylose maize starch

Background/objectivesThe health benefits provided by resistant starch have been well documented; however, few studies are available on the resistant starch content of wheat products in India. Moreover, few studies have examined the in vivo efficacy of resistant starch in wheat products in improving glucose levels. This study was conducted to evaluate the effect of cooking and storage temperature on the formation of resistant starch in Indian wheat products and its effect on blood glucose levels in humans and rats.MethodsWheat products were prepared by common cooking methods including roasting (Chapati), boiling (Dalia), Shallow frying (Paratha), and Deep frying (Poori). They were then stored at different temperatures including freshly prepared within 1 h (T1), stored for 24 h at room temperature (20-22°C) (T2), kept at 4°C for 24 h (T3) and reheated after storing at 4°C for 24 h (T4). The products were then analyzed for proximate composition (moisture, crude protein, crude fat, ash crude fibre, and carbohydrates). The effect of different cooking methods and storage temperatures on Resistant, non-resistant and total starch, total dietary fibre (soluble and insoluble), in vitro starch digestion rate (rapidly and slowly digestible starch), amylose and amylopectin content were analysed using standard operating procedures. The effect of products found to have higher resistant starch was studied on the post prandial blood glucose response of 10 healthy individuals using change in by analysing their glycemic index and glycemic load of wheat products. Further, the effect of resistant starch rich chapati on the blood glucose level of rats was also studied. Tukey’s test in factorial CRD was used to assess the effect of cooking and temperature on various parameters.ResultsThe amount of resistant starch was found to be high in dalia (boiling, 7.74%), followed by parantha (shallow frying, 4.94%), chapati (roasting, 2.77%) and poori (deep frying 2.47%). Under different storage temperatures, it was found high in products stored at 4°C (T3), followed by products stored at room temperature (T2), reheated products (T4) and lesser in freshly prepared products (T1). The glycemic index and glycemic load were found low in chapati (43, 32.3) and dalia (41.1, 28.6) stored at 4°C (T3) compared to others. The resistant starch content found in chapati stored at T3 was found to be more effective at reducing blood glucose levels in rats from 291.0 mg/100 mL to 225.2 mg/100 mL in 28 days of study compared to freshly prepared chapati (T1) and stored at room temperature (T2).ConclusionCooking methods including boiling, roasting and shallow frying increased the amount of resistant starch in foods, but cooking methods such as deep frying decreased the amount of resistant starch in food. Products stored at 4°C and at room temperature for 24 h increased the amount of resistant starch whereas the products that were freshly cooked and reheated decreased the amount of resistant starch in foods. At 4°C the stored products have a high amount of insoluble dietary fibre, slowly digestible starch, high amylose and low glycemic index. They take time to digest, meaning that they slowly increase blood glucose levels. The effect of insoluble dietary fibre and resistant starch in the inhibition of glucose diffusion in the small intestine is suggested to be due to the absorption or inclusion of the smaller sugar molecules. In vivo research showed that fibre and resistant starch in the digestive system of rats acts as the main factors in slowing glucose absorption and reducing a rise in blood glucose levels by promoting glycogen synthesis and inhibition of gluconeogenesis.