Rapidly Digestible Starch Content Research Articles

The Influence of Different Polyphenols on the Digestibility of Various Kinds of Starch and the Value of the Estimated Glycemic Index

Considering the prevalence of diet-related diseases, new ways of preventing them are being sought. One of them is the addition of polyphenols to high-starch products to inhibit their digestibility and reduce their glycemic index. Therefore, this study aimed to investigate the differences between polyphenols popular in food ((+)catechin, epigallocatechin gallate, quercetin, kaempferol, naringenin, hesperidin, trans-ferulic acid, and p-coumaric acid), in terms of their impact on wheat, rice, potato, and maize starch digestibility. Polyphenols were added to starch separately, before and after its pasting, in one of the following doses: 5, 10, and 20 mg. Starch was digested in the presence of single polyphenols to measure RDS (rapidly digestible starch), SDS (slowly digestible starch), RS (resistant starch), and TS (total starch) content. On that basis, the SDI (starch digestion index) was calculated, and the GI (glycemic index) was estimated. The results show that polyphenols inhibit starch digestion at different levels depending on the type of tested starch and the time of polyphenol addition. However, in terms of RDS, TS, and eGI (estimated glycemic index), the greatest impact was observed for epigallocatechin gallate in a dose of 20 mg most frequently, independently of the kind of tested starch and the time of polyphenol addition.

Physicochemical and digestible properties of corn starch/gelatin complexes: Effect of pH, type of gelatin, and gelatin/starch ratio

Reducing the starch digestibility is particularly important for the prevention of obesity, diabetes and other related diseases. This work evaluated the effects of type-A gelatin (GA) or type-B gelatin (GB) of different ratios (12.5%, 25.0% and 50.0%, gelatin/starch, w/w) on the in vitro digestibility of corn starch (CS) at pH 4.0, 5.0 and 6.0. The complexation of CS and gelatin was electrostatic interactions and hydrogen bonds. The gelatin addition increased the turbidity of the system, the gelatinization temperature of CS, decreased the rapidly digestible starch (RDS) content, crystallinity, gelatinization enthalpy and viscosity of CS, and embedded within the internal CS matrix. At the same pH, the RDS content decreased with the increase of GA/CS or GB/CS ratio except for the TS -25.0%GA sample at pH 4.0. Ranked in order of RDS content, the pH values of the complexes were generally as follows: pH 5.0 > pH 6.0 > pH 4.0. Compared to GB, GA significantly reduced RDS content of CS under the same gelatin/starch ratio and pH conditions. The TS-25.0%GA complex exhibited the lowest RDS content of 56.36% at pH 4.0. These results will help to learn more about the mechanism of interaction between CS and gelatin, as well as the development of low content RDS corn starch-based food.

Electron beam irradiation application for improving the multiscale structure and enhancing physicochemical and digestive properties of acetylated naked barley

The study used electron beam (EB) irradiation pretreatment to prepare acetylated (AC) naked barley starch. EB pretreatment enhanced the degree of substitution in acetylation from 0.027 to 0.109 %. The starch granules treated with EB and AC had a rough surface but maintained integrity. EB depolymerized the starch structure, providing opportunities for molecular rearrangement, thereby increasing the efficiency in the subsequent acetylation process. Therefore, EB pretreatment decreased AC starch amylose content (27.82 to 21.61 %), amylopectin molecular weight, relative crystallinity (31.04 to 26.23 %), short-range order, and increased amylose molecular weight comparing EB or AC-treated alone. These structural changes improve the properties of starch; thus, EB pretreatment reduced the thermal transition temperature, gelatinization enthalpy, pasting parameters, rapidly-digestible starch content (67.09–51.74 %), solubility, and improved content of slowly-digestible starch (23.82–36.65 %) and resistant starch (9.09–11.62 %). EB pretreatment can enhance efficiency and improve the structure and performance of acetylated modified starch.

Effect of Microwave Treatment on the Properties of Starch in Millet Kernels

AbstractThe microwave is widely applied to process cereals and grains. However, its effects on their chemical components are still not explored clearly. In this study, millet kernels are treated by microwave. The physical and chemical properties of starch in microwave‐treated millet kernels (SMM) are investigated and compared to those in untreated millet kernels (SUM). The experimental results indicate that the peak viscosity of SMM reduces with the increase of microwave time and initial moisture content of millet kernels (IMM). The peak viscosity of SUM is 831.00 BU. Compared with that of SUM, the peak viscosity of SMM decreases after microwave treatment (MT). When the IMM is 35%, the peak viscosity of SMM decreases by 66.23%. MT significantly increases (p < 0.05) the rapidly digestible starch (RDS) and slowly digestible starch (SDS) content of SMM, which reduces its resistant starch (RS) content. Under MT time of 150 s, the SDS of SMM is up to 35.92%. When the IMM is 35%, after MT, the RDS content of SMM reaches 52.10%. Additionally, the relative crystallinity and short‐range order of SMM are both decreased after MT. Therefore, the microwave is a useful tool for improving the properties of the starch in millet.

Effects of heating method and refrigerating time on nutritional quality and digestive characteristics of refrigerated Chinese steamed bread

Two re-heating methods and different refrigerating time were carried to compare the re-heating stored, refrigerated bread quality. Compared with the natural thawed steamed, sensory properties of re-heating bread were significantly improved, steam method improved moisture content while that re-heated by microwave decreased, the secondary structure of protein was significantly affected by re-heating. Rapidly digestible starch (RDS) content in bread re-heated by steam and by microwave decreased significantly, compared with fresh bread. With the storage time increasing, the sensory quality of bread showed a downward trend after being re-heated by steam; water content increased and then decreased; β-turn decreased gradually, while random coil increased gradually; starch aging showed a trend of gradual enhancement. RDS content and protein digestibility decreased gradually. Nutritional quality of the bread re-heated by steam was better than that by microwave, optimum cold storage time for the bread re-heated by steam should be no more than 24 h.

Genetic variability and genome‐wide marker association studies for starch traits contributing to low glycaemic index in pearl millet

AbstractPearl millet grains are naturally rich in high quality starch, dietary fibre, polyphenols and important micronutrients. Grains from a random subset of the global diversity panel (PMiGAP) comprising 166 pearl millet accessions were assessed for total starch (TS), rapidly digestible Starch (RDS), slowly digestible starch (SDS) and resistant starch (RS) content based on available glucose percentage after digestion at various time points. Highly significant genetic variations for SDS, RS and other starch traits were evident amongst the PMiGAP accessions leading to the identification of best accessions for use in the future pearl millet‐breeding programmes. To identify potential candidate genes associated with these starch traits, genome‐wide association studies (GWAS) were performed using 78K single‐nucleotide polymorphisms (SNPs) well distributed across the seven chromosomes of pearl millet. A total of 902 SNPs showed a strong association with various starch traits at ‐log p‐value range from 4.0–9.08. A total of 364 probable candidate genes were identified in the flanking regions of the significantly associated SNPs and high LD (linkage disequilibrium) region, which explains a correlation between nearby variants. Out of these, 19 probable candidate genes exhibited functional relationships with the starch biosynthesis pathway. Three starch synthase genes (Pgl_GLEAN_10026059 and Pgl_GLEAN_10027180) were found to be key probable candidate genes for SDS owing to their prior demonstrated involvement in amylose biosynthesis. Pgl_GLEAN_10018323, encoding β‐amylase and Pgl_GLEAN_10009197, encoding α‐amylase enzyme were identified as probable candidate genes for RDS content. The genetic variability being reported for SDS and RS in the germplasm panel, and the SNP markers associated with such variability, raises the possibility of developing pearl millet varieties with low glycaemic index using conventional and molecular breeding approaches.

Effect of Heat-Moisture Treatments on Digestibility and Physicochemical Property of Whole Quinoa Flour.

The starch digestion processing of whole grain foods is associated with its health benefits in improving insulin resistance. This study modified the digestibility of whole quinoa flour (WQ) via heat-moisture treatment (HMT), HMT combined with pullulanase (HMT+P), HMT combined with microwave (HMT+M), and HMT combined with citric acids (HMT+A), respectively. Results showed that all the treatments significantly increased (p < 0.05) the total dietary fiber (TDF) content, amylose content, and resistant starch (RS) content, however, significantly decreased (p < 0.05) the amylopectin content and rapidly digestible starch (RDS) content of WQ. HMT+P brought the highest TDF content (15.3%), amylose content (31.24%), and RS content (15.71%), and the lowest amylopecyin content (30.02%) and RDS content (23.65%). HMT+M brought the highest slowly digestible starch (SDS) content (25.09%). The estimated glycemic index (eGI) was respectively reduced from 74.36 to 70.59, 65.87, 69.79, and 69.12 by HMT, HMT+P, HMT+M, and HMT+A. Moreover, a significant and consistent reduction in the heat enthalpy (ΔH) of WQ was observed (p < 0.05), after four treatments. All these effects were caused by changes in the starch structure, as evidenced by the observed conjunction of protein and starch by a confocal laser scanning microscope (CLSM), the decrease in relative crystallinity, and transformation of starch crystal.

New insights into how starch structure synergistically affects the starch digestibility, texture, and flavor quality of rice noodles

The functionalities of gluten-free rice noodles are significantly affected by starch hierarchical structures. Identifying the structures that synergistically determine noodle integrated functionalities is vital to designing health-promoting starchy foods with desirable consumer sensory and nutritional qualities. This study reports on the changes in starch structures and functionalities (starch digestibility, texture, and flavor) of rice noodles during household cooking processes (steaming, boiling, and stir-frying), and describes an underlying structure-functionality relationship. Results show that all the cooking processes examined increased starch reassembled ordered structures, especially short-range ordered structures, helical and crystalline structures, and ordered aggregate structures. Steaming and boiling led to a decrease in rapidly digestible starch (RDS) and an increase in slowly digestible starch, while stir-frying yielded a reduction in RDS content and an increase in resistant starch in rice noodles. Steaming and boiling decreased while stir-frying increased the flavor variety of noodles. All cooking processes examined altered noodle textures, with a significant increase in hardness, gumminess, and chewiness. Structure-functionality relationships suggested short-range ordered structures, crystalline structures, and the ordered molecular and aggregate structures of noodles synergistically determined starch digestion, texture, and flavor. By structuring such key structures, the digestion, texture, and flavor of rice noodles can thus be reasonably controlled.

Effect of Annealing on Structural, Physicochemical, and In Vitro Digestive Properties of Starch from Castanopsis sclerophylla

AbstractAnnealing is a hydrothermal treatment that changes the structural and functional properties of starches. This study investigates and compares the effects of one‐step annealing for 24 and 48 h, respectively, and two‐step annealing on the structural, physicochemical, and digestive properties of Castanopsis sclerophylla starch (CaS). Annealing has no effect on CaS morphology, crystalline pattern, and short‐range ordered structures. However, annealing decreases the swelling power, solubility, setback, and peak viscosity of CaS and increases its crystallinity and thermal stability. Post annealing, the rapidly digestible starch (RDS) of CaS decreases, the slowly digestible starch (SDS) increases while the resistant starch (RS) content of CaS remains unchanged. Comparing with One‐step annealing for 24 h, one‐step annealing for 48 h and two‐step annealing does not further change the RDS and SDS content of annealed CaS.

Changes in physicochemical, nutritional characteristics and ATR-FTIR molecular interactions of cereal grains during germination.

The cereal grains such as wheat, barley, sorghum, millets were evaluated before and after germination (24h, 48h and 72h) and compared for their proximate composition, antioxidant activity, total phenolic content, total flavonoid content, pasting properties, in vitro starch digestibility and FTIR spectroscopy. Germination inversely affected the protein, fat, and ash content of different cereal grains. The germinated flours have less water content and higher oil absorption capacities along with reduced starch content. The contents of rapidly digestible starch (RDS), slowly digestible starch (SDS) and resistant starch (RS) in the ungerminated cereal flours ranged from 20.7 to 32.1%, 26.9 to 38.0% and 6.2 to 17.6% respectively but after germination of 72h, the RDS content increased from 26.5 to 36.2% while SDS and RS content decreased from 26.1% (sorghum) to 16% (barley) and 14.7% (barley) to 4.6% (wheat) respectively. The drought-tolerant crops (sorghum, millets and barley) are potential sources of antioxidants and phenolic content and yielded lower hydrolysis index and estimated glycaemic index upon germination. The highest section of antiparallal β-sheet, α-helix and β-turns were found in wheat flour followed by sorghum flour and their proportion decreased with continuous germination. The continuous reduction of viscosity was evaluated with the progress in germination. Overall, germination is a way to get health-promoting compounds from less utilizing cereal such as millets, sorghum and barley and enhance their uses to nourish the huge population with the aim to fulfill their nutritional requirements.

Influence of Storage Period on the Physicochemical Properties and In Vitro Digestibility of Starch in Packaged Cooked Chestnut Kernel

AbstractLong shelf life is important for industrially packaged cooked chestnut kernel. This study aims to investigate the physicochemical and digestive properties of starch in cooked chestnut stored for varying periods of up to 12 months. Apparent amylose content decreases significantly during the initial storage period of 2 months and then increases gradually in the succeeding 10 months. During storage, the degree of gelatinization decreases, whereas the degree of retrogradation (DR) increases. The relative crystallinity of cooked chestnut starch increases during storage and shows a significant positive correlation with DR. The content of rapidly digestible starch (RDS) decreases significantly during shelf life. Starch retrogradation and relative crystallinity exhibit a significant negative correlation with RDS content, and the short‐range molecular order of starch is negatively correlated with the content of slowly digestible starch. The results indicate that the digestibility of cooked chestnut kernel decreases during storage because of an increase in the crystallinity of starch.

Digestibility of common native starches with reference to starch granule size, shape and surface features towards guidelines for starch‐containing food products

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.

Optimization of Processing Condition of Instant Rice to Lower the Glycemic Index.

White rice is classified as having a low to high glycemic index (GI) depending on its amylose:amylopectin ratio. High GI food can be detrimental to diabetics since they can rapidly increase the glucose level in blood during digestion. Instant rice is increasing in popularity and is produced by dehydrating whole grain cooked rice, therefore, to make it more suitable for diabetics, the effect of the processes involved in the production on GI were tested. The objective was to optimize cooking temperature and the ratio of water to rice to reduce in vitro starch digestibility and GI of instant rice made from three Thai rice cultivars (Hom Mali (KDML105), Pathumthani Fragrant (PT) and Sao Hai (SH)) that had different amylose contents. Response surface methodology (RSM) was used to optimize the cooking conditions. The rapidly digestible starch (RDS) content and estimated glycemic index (eGI) decreased as cooking temperature decreased and the ratio of water to rice increased. The decrease in RDS content was associated with the increase in both slowly digestible starch (SDS) and resistant starch (RS) contents. The microstructure of instant rice kernels after cooking at higher temperature or lower volumes of water showed larger voids and a less compact surface, which facilitated enzymatic accessibility and increased starch digestibility. Rice cooked at higher temperature (90 °C) showed lower peak viscosity and breakdown in pasting properties, compared with lower temperature 82 °C. The optimal cooking condition for producing lower GI instant rice was cooking at 82 °C with 1.9-fold water volume. PRACTICAL APPLICATION: Rice has a high glycemic index (GI) that makes it unsuitable for consumption by many people with type 2 diabetes and obesity. Therefore, preparation of an instant rice product with a lower GI would ensure the product was beneficial to a wider range of the population.

Digestion rate of tapioca starch was lowed through molecular rearrangement catalyzed by 1,4-α-glucan branching enzyme

The 1,4-α-glucan branching enzyme (GBE) was used to modify native starch. GBE treatment resulted in the molecular rearrangement of tapioca starch, leading to an increase in the α-1,6 linkage content, the weight ratio of the short-chain fraction to the long-chain fraction (SF:LF), the content of cyclic molecules, and a decrease in the average ECL. GBE treatment also suppressed the digestion rate of starch. The magnitude of these changes increased in a time-dependent manner. After a 10-h GBE treatment, the rapidly digestible starch (RDS) content of starch was decreased by 14.5%. The RDS content was negatively related with the α-1,6 glycosidic linkage content (R2 = 0.8982) and the SF:LF ratio (R2 = 0.9646) but positively related with the average ECL of starch (R2 = 0.9406). Cyclic structures may also have suppressed the hydrolytic activity of pancreatin and amyloglucosidase. These joint actions of the molecular rearrangements catalyzed by GBE, not just the increase in α-1,6 linkage content, provides a mechanistic basis for the digestion rate reduction.

Fetal autopsy: Case report

The in vitro digestibility, molecular structure and crystalline structure of waxy rice starches isolated from six Korean cultivars (Shinsun, Dongjin, Baekok, Whasun, Chungbaek, and Bosuk) were investigated. The molecular weight (Mw) of waxy rice starches ranged from 1.1 × 108 g/mol to 2.2 × 108 g/mol. Chungbaek waxy rice starch had the highest average chain length (24.3) and proportion (20.7%) of long branch chains (DP ≥ 37), and the lowest proportion (19.0%) of short branch chains (DP 6–12) among the tested six waxy rice starches. The relative crystallinity and intensity ratio of 1047/1022 ranged from 38.9% to 41.1% and from 0.691 to 0.707, respectively. Chungbaek had the highest gelatinization temperature and enthalpy. Chungbaek had the highest pasting temperature (70.7 °C), setback (324 cP) and final viscosity (943 cP), whereas Baekok showed the highest peak viscosity (1576 cP) and breakdown (1031 cP). Chungbaek had lower rapidly digestible starch (RDS) content and expected glycemic index (eGI), and higher resistant starch (RS) content, whereas Whasun exhibited higher RDS content and eGI. The slowly digestible starch (SDS) content of Shinsun (38.3%) and Bokok (32.0%) was significantly higher than that of other cultivars (11.3–22.0%).

Influence of micronization on physicochemical properties of maize grains

Micronization of maize varieties viz. Nityashree (NAH-2049) and Arjun (EH-434042) was carried out in a near-infrared (NIR) based system. Infrared (IR) processing conditions such as moisture content and time of exposure were standardized to inactivate peroxidase and lipase enzymes and, to improve starch digestibility. Micronization of maize at 200°C for 4 min resulted in 16–20% increase in rapidly digestible starch (RDS) content. The process was effective in completely inactivating peroxidase enzyme and reducing lipase activity by 83–86%. The process did not induce any marked changes in total carbohydrates and protein contents. Reduction in pasting viscosities, peak viscosity (PV), and set back viscosity (SV) of micronized maize flour indicated partial gelatinization of starch. Micronized Arjun flour exhibited higher RDS content, which was correlated with lower viscosity profile values compared to Nityashree flour. Inactivation of enzymes in micronized maize provides the scope for shelf-life extension of flour. Improvement in RDS content increased water absorption capacity, and low viscosity profile provides an opportunity for its inclusion in preparing calorie dense foods having high solids concentration.

Impact of germination on the structures and in vitro digestibility of starch from waxy brown rice

The in vitro digestibility as well as the molecular and crystalline structures of waxy rice starches isolated from brown rice, germinated brown rice (GBR), ultrasonicated GBR, and heat-moisture treated GBR were investigated. The germinated brown rice starch (GBRS) had a lower average molecular weight and a higher proportion of DP 6-12 in amylopectin than brown rice starch (BRS). The relative crystallinity, intensity ratio of the band at 1047cm−1 and 1022cm−1, gelatinization temperature and pasting temperature of waxy rice starch were reduced by germination. However, the ultrasonication and heat-moisture treatment of GBRS increased the relative crystallinity and gelatinization temperature. The digestibility of starch from brown waxy rice was increased by germination. The rapidly digestible starch (RDS), slowly digestible starch (SDS) and resistant starch (RS) contents were 50.5%, 42.4%, and 7.1% in BRS, and 69.0%, 27.9% and 3.1% in GBRS, respectively. The ultrasonication and heat-moisture treatment of GBRS reduced RDS content and increased RS content in raw and gelatinized starches. The decrease in starch digestibility of cooked GBR was more pronounced after heat-moisture treatment than after ultrasonication.

Effect of extrusion on morphology, structural, functional properties and in vitro digestibility of corn, field pea and kidney bean starches

Native and extruded corn, field pea (FP), and kidney bean (KB) starches were evaluated for structure, in vitro digestibility and functional properties. Starches were extruded at 20 and 24% feed moisture (FM) using a twin screw extruder. Starches extruded at higher FM showed higher L* (luminosity) values while lower a* and b* values. Extrusion led to complete structure destruction, reduced crystallinity and formation of V type polymorph in starches. Extruded starches showed lower water absorption index (WAI), retrogradation (syneresis) and paste viscosities but higher water solubility index (WSI) as compared to native starches. CS showed lower retrogradation tendency than KB and FP starches. WAI, WSI, and retrogradation were higher at lower FM than those at higher FM. Extruded starches showed higher rapidly digestible starch (RDS) and lower resistant starch (RS) content. All starches extruded at higher FM showed significantly lower RDS content as compared to those extruded at lower FM. KB showed the highest RS content followed by FP and CS. Starches extruded at higher FM showed higher RS content as compared to those extruded at lower FM.

Influence of molecular structure on physicochemical properties and digestibility of normal rice starches

Normal rice starches were isolated from six different rice varieties grown in Korea and their molecular structure, crystalline structure, and in vitro digestibility were investigated. Apparent amylose content was the highest in starch from Junam cultivar (25.5%) and lowest in Hopum (22.4%). Starch from Hiami cultivar had the lowest molecular weights of amylose and amylopectin, average amylopectin chain length, proportion of short chains (DP 6–12), and proportion of long chains (DP≥37) among the tested rice starches. The relative crystallinity and ratio of 1047/1022 ranged from 30.2 to 36.7% and from 0.638 to 0.652, respectively. Hiami had the lowest gelatinization temperatures and the highest gelatinization enthalpy. Hiami had the highest pasting temperature (92.1°C), the lowest setback (515cP) and final viscosity (876cP), whereas Hanareum had the lowest pasting temperature (82.7°C), the highest setback (1002cP), and final viscosity (1580cP). The rapidly digestible starch (RDS), slowly digestible starch (SDS), and resistant starch (RS) content ranged from 43.9–53.5%, 35.5–52.6%, and 0.5–15.6%, respectively. The Junam cultivar had the lowest RDS content, whereas Hiami had the highest RDS content. The RS content of Hanareum (16.2%) and Boramchan (14.5%) was significantly higher than that of other normal rice cultivars (3.0–6.5%).

Micronization of maize flour: Process optimization and product quality

Micronization refers to high temperature short time processing of grains using near infrared rays. The present study is focused on optimization of process conditions for micronization of maize flour with an emphasis on enhancing rapidly digestible starch (RDS) content for enhancing starch digestibility and inactivation of peroxidase enzyme for probable extension of shelf-life. The study employed a central composite design (CCD) with three variables namely, time (60–180 s), temperature (130–170 °C) and moisture content (20–40%) with RDS and peroxidase contents as responses. The optimized micronization conditions (173 s, 159 °C, 40% mc; 164 s, 166 °C and 40% mc) resulted in 7.1–7.7% increase in RDS content and 92.5–96.2% inactivation of peroxidase enzyme, respectively, without significantly affecting protein, carbohydrate and fat content of flour. Validation studies showed that experimental values matched well with that of predicted, suggesting suitability of the model used. At the optimized conditions, micronization was also able to inactivate lipase activity by 66.9–68.2%.