Slow Digestion Research Articles

Insights into the rheological properties, multi-scale structure and in vitro digestibility changes of starch-β-glucan complex prepared by ball milling

High amylose corn starch (HACS)-oat β-glucan (OBG) complex was prepared by ball milling treatment. The morphology and structure of the samples were characterized, and the digestibility of the samples was studied. SEM analysis showed that the grain structure of oat β-glucan-starch after ball milling showed an irregular aggregate shape. The rheological results indicated that the apparent viscosity of the solution of HACS-OBG complex prepared by ball milling, with the values of both G′ and G″ decreasing on the increase of OBG addition. Multi-scale structure analysis showed that the disorder of the crystal structure and short-range structure of the HACS-OBG complex would lead to the decrease of the double helix structure content. In terms of digestibility, the RDS of the complex decreased from 75.88 % to 66.26 %, which suppressed the digestibility of starch. Molecular docking and quantum chemistry techniques further demonstrated the strong hydrogen bond interaction between HACS and OBG and the inhibition rate of OBG on the enzyme, which was conducive to the slow digestion of HACS-OBG complex. Therefore, ball milling treatment can promote the binding of OBG to starch, which may be an effective method for postprandial blood glucose control.

Seaweed as a Potential New Source for Starch, Produced in the Sea: A Short Review

AbstractThe social concern with sustainable development encourages the study of new sources of starch; among these sources, the cultivation of macroalgae is a strategy for the development of a sustainable bioeconomy. This mini‐review aims to present the main aspects related to the current seaweed market, the extraction, composition, and properties of starch, as well as its prospects as a sustainable ingredient capable of generating income and health for the world's population. The green algae species Ulva has been suggested as a promising source for starch extraction; however extraction is a challenge mainly due to the difficulty in breaking down the cell walls and isolating the starch granules. The algal starch granule is small (1.7–7 µm), and another characteristic is the high amylose content, above 55%, which may indicate that it is a resistant starch or slow digestion. Seaweed starch still needs to be scaled its production, extraction, and application potential, as a main ingredient or as a co‐product of gum processing, which already have a production chain, as they have great potential as nutraceutical or functional starch for food of low calorie, or for applications as a thickener in the food, cosmetics, and other industries.

A novel starch-based microparticle with polyelectrolyte complexes and its slow digestion mechanism

Encapsulation with polyelectrolyte complexes (PECs) was a novel approach to construct the starch based-microparticle with slow digestibility. In this study, sodium alginate (SA), gellan gum (GG) and chitosan (CS) were used to prepare SA/GG/CS based-PECs, while potato starch (PS) or its complex with lauric acid (PSL) were taken as the starch materials to obtain the starch based-microparticles (PSM or PSLM, respectively). The characteristic properties, morphological features, stability, and in vitro digestibility of their microparticles were investigated. From structure aspect, the PECs were steadied by the electrostatic interactions from negative and positive donors, and wrapped around starch granules to form the highly-hydroscopic hydrogel. This structure could withstand the heating treatment and in vitro simulated digestive fluid to some extent, thereby exhibiting better stability and slower digestibility than starch samples. Also, the slowly digestible starch content and the resistant starch content could be preserved at high levels, especially for PSLM. Besides, the release rate of lauric acid from PSLM was still low during the in vitro simulated digestion, which was also beneficial to health in terms of fatty acid intake. Hence, that was to say that the starch microparticle with SA/GG/CS based-PECs had the potential to be utilized in diet for hyperglycemia patients.

Effect of thermal treatments and non‐starch fraction on in vitro starch digestibility of oat bran

The effects of removing non-starch constituents like lipids, proteins, and β-glucan on the in-vitro digestibility of oat bran by steaming, microwaving, and hot air drying were investigated in this study. The results showed that the rapidly digestible starch (RDS) content of steaming oat bran decreased significantly (p < 0.05), and the glycemic index (e GI) was the lowest (66.11). The resistant starch (RS) content decreased, and in vitro digestibility, hydrolysis index, and eGI values of pretreated oat bran increased after removing the non-starch constituents. Lipid removal increased in vitro digestibility the most, followed by β-glucan and protein removal. The solubility of oat bran with removing protein increased significantly after steaming and microwaving treatment (p < 0.05). The relative crystallinity of oat bran decreased during steaming and increased after microwave and hot air drying. In conclusion, co-existed components like proteins, fiber and lipids are helpful to a purpose of a low GI and slow starch digestion. Practical applications In this study, high value-added utilization of oat bran was realized, which solved the problems of resource waste and environmental pollution. Meanwhile, the steaming oat bran with intact structure is helpful for a purpose of low GI and slow starch digestion and is more beneficial to human health.

190 Hyperosmolar salt concentrations slow digestion of milk and meconium by pancreatic enzymes

190 Hyperosmolar salt concentrations slow digestion of milk and meconium by pancreatic enzymes

Dietary compounds slow starch enzymatic digestion: A review.

Dietary compounds significantly affected starch enzymatic digestion. However, effects of dietary compounds on starch digestion and their underlying mechanisms have been not systematically discussed yet. This review summarized the effects of dietary compounds including cell walls, proteins, lipids, non-starchy polysaccharides, and polyphenols on starch enzymatic digestion. Cell walls, proteins, and non-starchy polysaccharides restricted starch disruption during hydrothermal treatment and the retained ordered structures limited enzymatic binding. Moreover, they encapsulated starch granules and formed physical barriers for enzyme accessibility. Proteins, non-starchy polysaccharides along with lipids and polyphenols interacted with starch and formed ordered assemblies. Furthermore, non-starchy polysaccharides and polyphenols showed robust abilities to reduce activities of α-amylase and α-glucosidase. Accordingly, it can be concluded that dietary compounds lowered starch digestion mainly by three modes: (i) prevented ordered structures from disruption and formed ordered assemblies chaperoned with these dietary compounds; (ii) formed physical barriers and prevented enzymes from accessing/binding to starch; (iii) reduced enzymes activities. Dietary compounds showed great potentials in lowering starch enzymatic digestion, thereby modulating postprandial glucose response to food and preventing or treating type II diabetes disease.

Effect of hydroxypropyl methylcellulose, protein and fat on predicted glycemic index and antioxidant property of gluten‐free bread from rice flour

Due to the lack of gluten, hydroxypropyl methylcellulose (HPMC), whey protein concentrate (WPC) and soy protein isolate (SPI) were fortified (4 g/100 g flour) into gluten-free bread made from rice flour. The heteropolymer structure of HPMC and protein covered starch granules, resulting in a decrease in predicted glycemic index (pGI) of bread from 84.08 to 67.20–71.04. Addition of butter reduced the pGI to 73.55. By changing the baking mode from hot air baking to microwave baking and microwave-hot air baking, the pGI was reduced from 73.55 to 70.51–70.81 (p ≤ 0.05). With addition of HPMC or/ and protein, the gluten-free bread exhibited stronger inhibition of 2,2-diphenyl-1-picrylhydrazyl (DPPH) radicals than the wheat bread. Therefore, starch digestibility of the gluten-free bread was mainly reduced by mixture of HPMC, proteins and butter in the dough recipe. Addition of HPMC and WPC further benefited the improvement of antioxidant activity by DPPH assay. Practical applications The finding of this research was the technique to manipulate GI and antioxidant activity in the rice-flour bread by microwave assisted baking process and addition of HPMC, WPC and butter. The outcome of this research could increase health benefit of gluten-free bread from rice flour, in terms of slow starch digestion and high antioxidant activity.

Incorporation of defatted quinoa flour affects in vitro starch digestion, cooking and rheological properties of wheat noodles

Quinoa is a lipid-rich pseudocereal, and lipid oxidation limits the shelf life of quinoa flour. It has been shown that defatting improves the storage properties of quinoa. However, there is a lack of research to support the application of defatted quinoa flour. The rheological properties of dough and in vitro starch digestibility, cooking quality, and texture properties of noodles containing 0%–30% (w/w) defatted quinoa flour (DQF) were investigated. The results showed that the storage modulus (G') of dough substituted with 10% DQF was higher than wheat dough, and the deformation decreased as the DQF content increased. Noodles with DQF (10–20%) had a lower cooking loss and water absorption than noodles with 10% full quinoa flour (FQF), while the noodles with 30% DQF exceeded the satisfactory point of industry standards for cooking loss. On the other hand, the noodles with DQF presented a higher hardness and chewiness than wheat noodles. In vitro digestion results showed two simultaneous digestion fractions for all noodle samples. The noodles' maximum digestion amount and slow digestion fraction content decreased by 5.77% and increased by 9.64%, respectively, with 10% DQF. Considering digestive and cooking characteristics of noodles, we recommend incorporating 10% DQF into noodle formulations. This study will provide scientific support to the industrial product application of quinoa noodles.

Effects of Extrusion on Starch Molecular Degradation, Order-Disorder Structural Transition and Digestibility-A Review.

Extrusion is a thermomechanical technology that has been widely used in the production of various starch-based foods and can transform raw materials into edible products with unique nutritional characteristics. Starch digestibility is a crucial nutritional factor that can largely determine the human postprandial glycemic response, and frequent consumption of foods with rapid starch digestibility is related to the occurrence of type 2 diabetes. The extrusion process involves starch degradation and order–disorder structural transition, which could result in large variance in starch digestibility in these foods depending on the raw material properties and processing conditions. It provides opportunities to modify starch digestibility by selecting a desirable combination of raw food materials and extrusion settings. This review firstly introduces the application of extrusion techniques in starch-based food production, while, more importantly, it discusses the effects of extrusion on the alteration of starch structures and consequentially starch digestibility in various foods. This review contains important information to generate a new generation of foods with slow starch digestibility by the extrusion technique.

In Vivo Digestibility of Carbohydrate Rich in Isomaltomegalosaccharide Produced from Starch by Dextrin Dextranase.

Slowly digestible carbohydrates are needed for nutritional support in diabetic patients with malnutrition. They are a good source of energy and have the advantage that their consumption produces a low postprandial peak in blood glucose levels because they are slowly and completely digested in the small intestine. A high-amount isomaltomegalosaccharide containing carbohydrate (H-IMS), made from starch by dextrin dextranase, is a mixture of glucose polymers which has a continuous linear structure of α-1,6-glucosidic bonds and a small number of α-1,4-glucosidic bonds at the reducing ends. It has a broad degree of polymerization (DP) distribution with glucans of DP 10－30 as the major component. In our previous study, H-IMS has been shown to exhibit slow digestibility in vitro and not to raise postprandial blood glucose to such levels as that raised by dextrin in vivo. This marks it out as a potentially useful slowly digestible carbohydrate, and this study aimed to evaluate its in vivo digestibility. The amount of breath hydrogen emitted following oral administration of H-IMS was measured to determine whether any indigestible fraction passed through to and was fermented in the large intestine. Total carbohydrate in the feces was also measured. H-IMS, like glucose and dextrin, did not result in breath hydrogen excretion. Carbohydrate excretion with dietary H-IMS was no different from that of glucose or water. These results show that the H-IMS is completely digested and absorbed in the small intestine, indicating its potential as a slowly digestible carbohydrate in the diet of diabetic patients.

Comparative RNA-Seq analysis unravels molecular mechanisms regulating therapeutic properties in the grains of traditional rice Kavuni

Developing rice varieties with enhanced levels of functional bioactives is an important intervention for achieving food and nutritional security in Asia where rice is the staple food and Type II diabetes incidences are higher. The present study was aimed at dissecting out the molecular events underlying the accumulation of bio active compounds in pigmented traditional rice Kavuni. Comparative transcriptome profiling in the developing grains of Kavuni and a white rice variety ASD 16 generated 37.7 and 29.8 million reads respectively. Statistical analysis identified a total of 9177 exhibiting significant differential expression (DEGs) between the grains of Kavuni and ASD 16. Pathway mapping of DEGs revealed the preferential up-regulation of genes involved in the biosynthesis of amylose and dietary fibres in Kavuni accounting for its low glycemic index (GI). Transcripts involved in the biosynthesis of carotenoids, flavonoids, anthocyanins, phenolic acids and phenylpropanoids were also found to be up-regulated in the grains of Kavuni. This study identified up-regulation of key transcripts involved in the accumulation of phenolic acids having potential for inhibiting major hydrolytic enzymes α-amylase and α-glucosidase and thus accounting for the slow digestibility leading to low GI. Overall, this study has identified molecular targets for the genetic manipulation of anti-diabetic and anti-oxidant traits in rice.

Effect of storage conditions on the textural properties and in vitro digestibility of wheat bread containing whole quinoa flour

This research aimed to clarify the evolution of textural characteristics and in vitro digestibility under different storage conditions. Quickly increasing hardness and decreasing resilience was observed in quinoa bread after 5d cold (4 °C) storage. However, when stored at −18 °C for 5d, bread crumb still maintains a dense alveographic with 52.33% of cell density and 33.76% area fractions. In addition, the starch digestion rate decreased with increasing retrogradation degree. Scanning electron microscope (SEM) characterizations illustrated that the chunky matrix gradually disappeared with digestion. However, quinoa starch (QS) granules were the most difficult to digest owing to the relative intactness and wrapping in the protein-starch bulk. Meanwhile, X-ray diffraction (XRD) showed that the crystal structure of starch remained 21.09% stored in frozen conditions, and wheat type-A (WA) starch was mainly involved in gelatinization. The results of water migration proved that water participated in the retrogradation of starch and affected the quality of quinoa bread. Overall, bread stored in frozen conditions can maintain good texture characteristics and slow starch digestion rate. This study indicates that quinoa flour fortified bread has the potential to be developed as staple food with both low glycemic index values and storage stability.

Effects of maltogenic α-amylase treatment on the proportion of slowly digestible starch and the structural properties of pea starch

In this study, pea starch was modified with maltogenic α-amylase and then its physicochemical properties, chain length distribution, and in vitro digestibility were examined. An analysis of the starch products resulting from the maltogenic α-amylase treatment revealed a decrease in the molecular weight, an increase in the proportion of short chains [degree of polymerization (DP) <13], a decrease in the proportion of long chains (DP > 13), and a decrease in viscosity, resulting in slower digestion. The results indicated that maltogenic α-amylase can selectively hydrolyze α-1,4- and α-1,6-glycosides to some extent. Cleaving the α-1,4 linkage of starch facilitated the transfer of the non-reducing D-glucosyl residues of maltose, thereby generating an α-1,6 branch linkage. The reaction between maltogenic α-amylase and pea starch was affected by the reaction time and enzyme concentration. The maximum slowly digestible starch content (38.5%) was obtained by digesting samples with 60.0 ppm maltogenic α-amylase for 4.0 h. These findings demonstrate that modifying pea starch using maltogenic α-amylase can generate starch products with new branching structures conducive to slow digestion.

Using buckwheat starch to produce slowly digestible biscuits with good palatability

AbstractBackground and ObjectiveDue to the rapid digestibility, cooked starch can cause a high postprandial blood glucose response (hyperglycemia), one of the risk factors for metabolic diseases, such as obesity and diabetes. The objective was to understand the properties of starch that provided slow digestibility in low‐moisture baked goods. Buckwheat (Fagopyrum esculentum Moench) starch was used to prepare biscuits with slowly digestible starch and was compared with wheat (Triticum aestivum) starch.FindingsBuckwheat starch had higher gelatinization temperature and smaller breakdown viscosity (in pasting curve) than wheat starch. Slower starch digestion rate and higher amount of undigested starch were observed when 60% (w/w) wheat flour in biscuits was substituted by buckwheat starch than by wheat starch. The biscuits containing buckwheat starch or wheat starch also showed a structure with lower firmness than the control biscuits.ConclusionBuckwheat starch was more resistant to gelatinization and breakage during baking, and thus was less susceptible to enzyme digestion in biscuits than wheat starch.Significance and NoveltyThis is the first study utilizing a starch having a normal amylose content without any modification, except partial gelatinization during baking, as a source of slowly digestible starch in biscuits. Buckwheat starch not only provided slow digestibility, but also improved the palatability of the biscuits, creating a smoother and less firm texture than those made using whole grain flour.

Preparation of Slowly Digested Corn Starch Using Branching Enzyme and Immobilized α-Amylase.

The aim of this study was to modify the digestibility and structure of corn starch by treatment with compound enzymes. Corn starch was treated with two enzymes (α-amylase, which catalyzes hydrolysis, and branching enzyme, a transglycosidase that catalyzes branch formation), and the reaction was monitored by determining the content of slowly digestible starch in the reaction product. The fine structure and physical and chemical properties of enzyme-modified starch samples were analyzed using scanning electron microscopy, gel chromatography, and X-ray diffraction methods; modified starch has a high degree of branching, a high proportion of short-chain branched structures, and greatly improved solubility. The results show that the slow digestion performance of corn starch was significantly improved after hydrolysis by α-amylase for 4 h and treatment with branching enzyme for 6 h. These results show that enzymatic modification of corn starch can improve its slow digestibility properties.

Soluble Papain to Digest Monoclonal Antibodies; Time and Cost-Effective Method to Obtain Fab Fragment.

Antigen binding fragments (Fabs) used in research (e.g., antibody mimetics, antibody-drug conjugate, bispecific antibodies) are frequently obtained by enzymatic digestion of monoclonal antibodies using immobilised papain. Despite obtaining pure Fab, using immobilised papain to digest IgG has limitations, most notably slow digestion time (more than 8 h), high cost and limited scalability. Here we report a time and cost-effective method to produce pure, active and stable Fab using soluble papain. Large laboratory scale digestion of an antibody (100 mg) was achieved using soluble papain with a digestion time of 30 min and isolated yields of 55–60%. The obtained Fabs displayed similar binding activity as Fabs prepared via immobilised papain digestion. Site-specific conjugation between Fabs and polyethylene glycol (PEG) was carried out to obtain antibody mimetics FpF (Fab-PEG-Fab) indicating that the native disulphide bond had been preserved. Surface-plasmon resonance (SPR) of prepared FpFs showed that binding activity towards the intended antigen was maintained. We anticipate that this work will provide a fast and less costly method for researchers to produce antibody fragments at large scale from whole IgG suitable for use in research.

The Underlying Physicochemical Properties and Starch Structures of indica Rice Grains with Translucent Endosperms under Low-Moisture Conditions.

Rice grain quality is a complex trait that includes processing, appearance, eating, cooking, and nutrition components. The amylose content (AC) in the rice endosperm affects the eating and cooking quality along with the appearance of milled rice. In this study, four indica rice varieties with different ACs were used to study the factors affecting endosperm transparency along with the physical and chemical characteristics and eating quality of translucent endosperm varieties. Endosperm transparency was positively correlated with water content and negatively correlated with the cumulative area of cavities within starch granules. The indica landrace 28Zhan had a translucent endosperm and exhibited good taste. Based on starch fine structure analysis, long-chain amylopectin and the B2 chain of amylopectin might be major contributors to the good taste and relatively slow digestion of this landrace.

Alkali-washing facilitates thermal-processed lignin to slow the hydrolysis of pancreatic α-amylase in starchy foods

Lignin, despite being able to slow starch digestion, needs to be heated at over 300 °C. To make the benefit achievable at a food-grade temperature, alkali-washing is studied as an additional procedure to facilitate the thermally processed lignin to slow the starch digestion in vitro. Lignin was firstly washed using Na2CO3/NaHCO3 mixture of various pH 7–10 followed by the thermal process at 150, 200, 250, and 300 °C respectively. The mild alkali-washing (pH 10) was found to allow the lignin heated at only 200 °C to achieve a significant inhibition on the hydrolysis of pancreatic α-amylase (α-AA) in starch-rich pasta. After the structural-characterization using atomic force microscopy and fluorescence spectroscopy, the mechanism hypothesis is confirmed due to a modification of insoluble-lignin surface morphology which might immobilize the α-AA content in solution. The findings highlight the potential of alkali-washing for facilitating thermally processed lignin in slowing the digestion of starchy foods.

α-Gal present on both glycolipids and glycoproteins contributes to immune response in meat-allergic patients

The α-Gal syndrome is associated with the presence of IgE directed to the carbohydrate galactose-α-1,3-galactose (α-Gal) and is characterized by a delayed allergic reaction occurring 2 to 6 hours after ingestion of mammalian meat. On the basis of their slow digestion and processing kinetics, α-Gal-carrying glycolipids have been proposed as the main trigger of the delayed reaction. We analyzed and compared the invitro allergenicity of α-Gal-carrying glycoproteins and glycolipids from natural food sources. Proteins and lipids were extracted from pork kidney (PK), beef, and chicken. Glycolipids were purified from rabbit erythrocytes. The presence of α-Gal and IgE binding of α-Gal-allergic patient sera (n= 39) was assessed by thin-layer chromatography as well as by direct and inhibition enzyme-linked immunosorbent assay. The invitro allergenicity of glycoproteins and glycolipids from different meat extracts was determined by basophil activation test. Glycoprotein stability was evaluated by simulated gastric and intestinal digestion assays. α-Gal was detected on glycolipids of PK and beef. Patient IgE antibodies recognized α-Gal bound to glycoproteins and glycolipids, although binding to glycoproteins was more potent. Rabbit glycolipids were able to strongly activate patient basophils, whereas lipid extracts from PK and beef were also found to trigger basophil activation, but at a lower capacity compared to the respective protein extracts. Simulated gastric digestion assays of PK showed a high stability of α-Gal-carrying proteins in PK. Both α-Gal-carrying glycoproteins and glycolipids are able to strongly activate patient basophils. In PK and beef, α-Gal epitopes seem to be less abundant on glycolipids than on glycoproteins, suggesting a major role of glycoproteins in delayed anaphylaxis upon consumption of these food sources.

Effects of dietary fibre and soybean oil on the digestion of extruded and roller‐dried maize starch

SummaryThe effects of soybean dietary fibre (SDF), microcrystalline cellulose (MCC), konjac glucomannan (KGM), soluble soybean polysaccharide (SSPS) and soybean oil (SO) on in vitro digestion of extruded maize starch (EMS) and roller‐dried maize starch (RDMS) samples were investigated. Adding MCC, particularly in high doses, induced slow digestion in EMS and RDMS samples, but not after adding SDF. KGM and SSPS addition reduced starch hydrolysis of RDMS but did not have a significant effect on EMS, whereas SO addition reduced starch hydrolysis of EMS but had no effect on RDMS. Principal component analysis demonstrated that the addition of MCC, SO, KGM (0.51%), and SSPS (0.51%) to EMS and KGM (0.51%) to RDMS were the best choices to slow the hydrolysis of starch, compared with that of other additives. These findings provide useful information on the selection of exogenous additives in the development of low glycaemic index products for maize starch.