Effects of β-glucan and various thermal processing methods on the in vitro digestion of hulless barley starch

Expression and characterization of two acidophilic β-1,3-1,4-glucanases from Trichoderma asperellum ND-1 suitable for cello-oligosaccharides production

Enzymatic transformation of plant biomass offers an desirable pathway to yield high-value macromolecules, e.g., cello-oligosaccharides. Two acidophilic GH16 family β-1,3-1,4-glucanases (TaGlu16A and TaGlu16B) from Trichoderma asperellum ND-1 were successfully expressed in Komagataella phaffii and estimated to be ∼30 and 50 kDa by SDS-PAGE. TaGlu16B was a glycoprotein with a carbohydrate content of ∼30 % (w/w). TaGlu16A and TaGlu16B exhibited maximum activities at pH 4.0 and 5.0, respectively. Both enzymes were ethanol-tolerant, retaining >70 % activities in the presence of 0-20 % ethanol. Substrate-specificity analysis suggested that TaGlu16A was exclusively active toward barley β-glucan (Vmax = 1041.5 μmol/min/mg, Km = 2.45 mg/mL), yielding tetrasaccharide and trisaccharide. Notably, TaGlu16B initially released tetrasaccharide and trisaccharide from barley β-glucan and further degraded into disaccharide and glucose, suggested a bifunctional enzyme with both endo-β-1,3-1,4-glucanase and exo-acting glucanase activities. Site-directed mutagenesis indicated that (Glu151 and Glu156) and (Glu134 and Glu139) were crucial catalytic residues for TaGlu16A and TaGlu16B activities, respectively. Moreover, the addition of TaGlu16A and TaGlu16B to saccharification process could remarkably reduce the viscosity by 6.21 and 8.69, and filtration time by 26.66 % and 39.25 %, respectively. These results provided insights into β-1,3-1,4-glucanase activities and paved the way for degradation of lignocellulosic biomass.

Characterization of glucans from diverse sources and their influence on fat and carbohydrate absorption, digestion in vitro, and glucose tolerance in vivo

Glucan, a recognized prebiotic primarily derived from fungi, bacteria, and plants, possesses significant nutritional value and biological activity. It serves as a thickener and emulsifier stabilizer, enhancing the texture and sensory properties of food. This study aimed to compare the inhibitory effects of glucans from yeast, oats, and bacteria on energy intake by characterizing their physicochemical properties and evaluating their impact on fat and glucose adsorption, starch and fat digestion in vitro, and glucose tolerance in vivo. The findings revealed that despite sharing similar active groups, the glucans exhibited distinct structures, viscosities, water solubilities, thermal degradation behaviors, and micromorphologies. All three sources demonstrated effectiveness in adsorbing fat and glucose, inhibiting starch and fat digestion, and improving glucose tolerance in mice, albeit with notable differences. Among these, Salecan glucan, derived from bacterial sources, exhibited superior performance in fat absorption, inhibition of starch and fat digestion, and enhancement of glucose tolerance. This is likely attributable to its higher viscosity, greater water solubility, and linear molecular structure. These results highlight the functional significance of glucans from different sources and underscore their potential application in developing functional foods aimed at managing energy intake.

Structural barriers governing starch digestibility in intact highland barley cells: A closer insight from cell wall and protein matrix

The endosperm cell structure plays an important role in starch digestion. This study aimed to evaluate the effects of the structural properties of the cell wall and protein matrix on starch digestibility in intact cells isolated from the endosperm of highland barley. Damaged cells with different degree of cell wall degradation were obtained by controlling the time of β-glucanase hydrolysis of isolated cells. Intact cells exhibited the lowest starch digestibility (61.80 %) and gelatinization enthalpy change (3.55 J/g). As the degree of β-glucanase hydrolysis increased, the starch digestibility of damaged cells markedly increased and was close to that of mechanically crushed flour. Penetration of amylase-sized fluorescent probes showed that the probes barely penetrated the raw and cooked cell walls, indicating that the cell wall strongly blocked the contact between amylase and starch. Additionally, the compound network formed by the protein matrix and expanded starch hindered probe diffusion. However, the starches in the cells with the greatest cell wall loss were fully digested after 6 h of digestion. Therefore, the cell wall, an effective structural barrier to amylase, mainly limits starch digestibility, whereas the protein matrix/network acts as a secondary barrier. This study provides new insights into the processing of slow-digested cereals.

Modulation of rice starch physicochemical properties and digestibility: The role of highland barley non-starch polysaccharide fractions

Highland barley non-starch polysaccharides (HBNP), particularly β-glucans, are known for their health-promoting effects, including modulation of glycemic response and enhancement of gut health. This study investigated the impact of different HBNP fractions on the properties and digestibility of high-glycemic index rice starch. HBNP was segmented into five fractions (HBNP-15, HBNP-30, HBNP-45, HBNP-60, and HBNP-75) using gradient ethanol precipitation, and these fractions exhibited varying molecular weights, monosaccharide compositions, and β-glucan contents. All fractions reduced rice starch's pasting viscosity, with 1 % HBNP-75 leading to a 99.1 % decrease in final viscosity. Morphological and size distribution analyses showed that HBNP fractions limited granule swelling and disrupted starch's continuous phase structure. HBNPs also reduced starch digestibility and increased the formation of resistant starch from 10 % to 28 %. These results suggest potential uses for HBNP fractions in developing low-glycemic starch-based foods.

Strategic exploration of whole grain cereals in modulating the glycaemic response

In the current context, diabetes presents itself as a widespread and complex global health issue. This study explores the significant influence of food microstructure and food matrix components interaction (protein, lipid, polyphenols, etc.) on the starch digestibility and the glycaemic response of post-prandial glycemia, focusing on the potential effectiveness of incorporating bioactive components from whole grain cereals into dietary strategies for the management and potential prevention of diabetes. This study aims to integrate the regulation of postprandial glycaemic homeostasis, including the complexities of starch digestion, the significant potential of bioactive whole grain components and the impact of food processing, to develop a comprehensive framework that combines these elements into a strategic approach to diabetes nutrition. The convergence of these nutritional strategies is analyzed in the context of various prevalent dietary patterns, with the objective of creating an accessible approach to mitigate and prevent diabetes. The objective remains to coalesce these nutritional paradigms into a coherent strategy that not only addresses the current public health crisis but also threads a preventative approach to mitigate future prevalence and impact.

A review of endogenous non-starch components in cereal matrix: spatial distribution and mechanisms for inhibiting starch digestion

As compared with exogenous components, non-starch components (NSCS), such as proteins, lipids, non-starch polysaccharides (NSPs), and polyphenols, inherently present in cereals, are more effective at inhibiting starch digestibility. Existing research has mostly focused on complex systems but overlooked the analysis of the in-situ role of the NSCS. This study reviews the crucial mechanisms by which endogenous NSCS inhibit starch digestion, emphasizing the spatial distribution-function relationship. Starch granules are filled with pores/channels-associated proteins and lipids, embedding in the protein matrix, and maintained by endosperm cell walls. The potential starch digestion inhibition of endogenous NSCS is achieved by altering starch gelatinization, molecular structure, digestive enzyme activity, and accessibility. Starch gelatinization is constrained by endogenous NSCS, particularly cell wall NSPs and matrix proteins. The stability of the starch crystal structure is enhanced by the proteins and lipids distributed in the starch granule pores and channels. Endogenous polyphenols greatly inhibit digestive enzymes and participate in the cross-linking of NSPs in the cell wall space, which together constitute a physical barrier that hinders amylase diffusion. Additionally, the spatial entanglement of NSCS and starch under heat and non-heat processing conditions reduces starch accessibility. This review provides novel evidence for the health benefits of whole cereals.

Exploring the relationship between starch structure and physicochemical properties: The impact of extrusion on highland barley flour

Highland barley (HB) is an intriguing plateau cereal crop with high nutrition and health benefits. However, abundant dietary fiber and deficient gluten pose challenges to the processing and taste of whole HB products. Extrusion technology has been proved to be effective in overcoming these hurdles, but the association between the structure and physicochemical properties during extrusion remains inadequately unexplored. Therefore, this study aims to comprehensively understand the impact of extrusion conditions on the physicochemical properties of HB flour (HBF) and the multi-scale structure of starch. Results indicated that the nutritional value of HBF were significantly increased (soluble dietary fiber and β-glucan increased by 24.05%, 19.85% respectively) after extrusion. Typical underlying mechanisms based on starch structure were established. High temperature facilitated starch gelatinization, resulting in double helices unwinding, amylose leaching, and starch-lipid complexes forming. These alterations enhanced the water absorption capacity, cold thickening ability, and peak viscosity of HBF. More V-type complexes impeded amylose rearrangement, thus enhancing resistance to retrogradation and thermal stability. Extrusion at high temperature and moisture exhibited similarities to hydrothermal treatment, partly promoting amylose rearrangement and enhancing HBF peak viscosity. Conversely, under low temperature and high moisture, well-swelled starch granules were easily broken into shorter branch-chains by higher shear force, which enhanced the instant solubility and retrogradation resistance of HBF as well as reduced its pasting viscosity and the capacity to form gel networks. Importantly, starch degradation products during this condition were experimentally confirmed from various aspects. This study provided some reference for profiting from extrusion for further development of HB functional food and "clean label" food additives.

The impact of different soluble endogenous proteins and their combinations with β-glucan on the in vitro digestibility, microstructure, and physicochemical properties of highland barley starch

The impacts of protein types and its interaction with β-glucan on the in vitro digestibility of highland barley starch were investigated through analyzing physicochemical and microstructural properties of highland barley flour (HBF) after sequentially removing water- (WP), salt- (SP), alcohol- (AP) and alkali-soluble (AlkP) proteins. Resistant starch (RS) increased significantly in HBF after removing WP and SP, and RS of HBF was lower than that of without β-glucan. After removing WP, SP and AP, swelling powers of HBF without β-glucan (9.33-9.77) were higher than those of HBF (12.09-15.95). Trends of peak viscosity and peak temperature (thermal degradation temperature) were similar as swelling power, and HBF without AP showed the highest peak temperature (310.33 °C). Removals of different proteins improved the crystalline structure and short-range order of starch. There was a blue shift in T2 values and an opposite change in free water proportion. The matrix on starch surface was mainly formed by AP and AlkP, which could be aggregated by β-glucan. But, the inhibitory effect of AP or AlkP was stronger than that of proteins combined with β-glucan. These results help in the development of starch-based foods with different digestive properties by combining different protein types with β-glucan.

Comparison of quinoa and highland barley derived dietary fibers influence on the physicochemical properties and digestion of rice starch

This study investigated the potential of highland barley and quinoa dietary fibers, rich in β-glucan and pectin respectively, as cost-effective and nutritionally valuable physical modifiers for rice starch (RS). HPAEC revealed differences between the monosaccharide composition of soluble and insoluble dietary fibers sourced from highland barley and quinoa (HSDF, HIDF, QSDF and QIDF). Results from both RVA and DSC analysis revealed that the addition of low amounts of dietary fiber significantly modified the pasting properties of RS. Notably, the addition of quinoa soluble dietary fiber (QSDF) significantly inhibits the formation of a stable gel network in rice starch, even at low concentrations (0.1 %), as confirmed by rheological measurements. Furthermore, the incorporation of QSDF effectively reduces the content of rapidly digestible starch in rice starch by 15.6 % and increases the content of slowly digestible starch, from 23.36 % ± 3.02 % to 31.07 % ± 3.98 %. By leveraging the compositional richness of these fibers, this research opens up novel opportunities for developing functional food products with improved nutritional profiles, as well as for improving texture and reducing glycemic index (GI) in starch-based foods.

Toward a comprehensive understanding of various milling methods on the physicochemical properties of highland barley flours and eating quality of corresponding sugar-free cookies

Highland barley (HB) was subjected to dry-, semidry-, wet-milling methods and assessed for flour physicochemical properties and eating quality of corresponding sugar-free cookies. Results showed that there were significant differences between different milled flours in damaged starch content, particle size, hydration, pasting properties, and color. High a* values and poor hydration/pasting properties of wet-milled flours were associated with its smallest particle size and lowest content of damaged starch (25.3%), β-glucan (1.87%), and dietary fiber (10.87%), resulting in dark brown color, slightly high spread ratio, low hardness, and fast digestibility of the corresponding cookies. Conversely, the low digestibility of the cookies (predicted glycemic index 58.85) prepared from dry-milled flours was attributed to the higher content of dietary fiber, β-glucan and V-type starch-lipid complex, which would affect enzyme accessibility and may be beneficial for making HB sugar-free cookies. This study is expected to promote the development of HB functional foods.

The contribution of cell wall integrity to gastric emptying and in vitro starch digestibility and fermentation performance of highland barley foods

Studies have shown that the structure, composition, and bioavailability of compounds in whole grains are affected by processing and the role of cells walls. In this study, the effects of different processing methods on highland barley, one of the mostly widely produced whole grains worldwide, were investigated. The processing methods applied were flaking-boiling (HB flake), sand-roasting (Puffed HB), and sand-roasting-milling (Tsamba). Results showed Puffed HB and Tsamba had higher levels of damaged starch content, starch short-range molecular order, and relative crystallinity than HB flake. The half-time of gastric emptying (t_1/2) was the slowest for Tsamba (132.3 min) compared to HB flake (122.5 min) and Puffed HB (84.0 min), indicating the slowest gastric emptying rate, which could be attributed to its high viscosity of gastric digesta. After in vitro gastroduodenal digestion, Puffed HB exhibited the lowest starch digestibility and the least amount of β-glucan due to its less damaged cellular structure. Furthermore, Puffed HB resulted in a 21% and 18% higher in vitro production of total short-chain fatty acids than Tsamba and HB flake, respectively. Besides, undigested starch of Puffed HB after in vitro gastroduodenal digestion delayed in vitro fecal fermentation of β-glucan. Our study provided insight into the potential mechanisms of how cell wall integrity affected the gastric emptying, in vitro starch digestibility, and in vitro fecal fermentation of highland barley foods.

Effects of cereal grain cell wall composition and structure on starch digestion

BACKGROUND

Wheat is an important food crop, and its characteristics vary depending on the region of cultivation; different environments have varying effects on the composition of the grains. We previously reported the effects of environmental factors on wheat grain cell wall composition and structure.

METHODS

The variations in the structure of aleurone cell walls between different wheat samples were examined to determine the effects of aleurone cell walls on grain starch digestion properties. Ten different varieties of wheat grains with different aleurone cell wall structure and composition constituted a simple research system used to study their effect on the starch digestion of bread.

RESULTS

The aleurone cell wall thickness ranged from 3.05 μm to 4.67 μm, and the arabinose to xylose ration of water-extractable arabinoxylan was 0.79-0.97. With the increase in arabinoxylans content or cell wall thickness, the total digestibility of starch within the bread decreased; this phenomenon may be related to the changes in the interaction between polysaccharides and starch granules in this process.

CONCLUSION

Our study showed that the wheat cell wall structure has a great impact on starch hydrolysis, indicating that the change in the digestibility of starch in flour and bread may be due to changes in the cell wall structure leading to different combinations, thus affecting digestibility. The present study showed that the cell wall combines the starch granules during the bread-making process; thus, the diffusion of enzymes through the cell wall was hindered. This article is protected by copyright. All rights reserved.

Effects of Highland Barley Flour with Different Particle Sizes on the Characteristics of Reconstituted Flour and Noodles

To study the effects of highland barley flour with different particle sizes on dough characteristics and noodle quality, highland barley flours (median particle sizes of 223.25, 143.12, 90.73, 42.33 and 19.26 μm, respectively) were mixed with the wheat flour to make noodles. The damaged starch content of highland barley flour with five particle sizes was 47.0, 61.0, 62.3, 102.0, and 108.0 g/kg, respectively. The reconstituted flour containing highland barley powder with smaller particle sizes showed higher viscosity and water absorption. The smaller the particle size of barley flour, the lower the cooking yield, shear force and pasting enthalpy of the noodles, and the higher the hardness of the noodles. As the particle size of barley flour decreases, the structural density of the noodles increases. This study is expected to provide a constructive reference for the development of barley-wheat composite flour and the production of barley-wheat noodles.

A novel chitinous nanoparticles prepared and characterized with black soldier fly (Hermetia illucens L.) using steam flash explosion treatment

This is the first report of the use of steam flash explosion (SFE) to prepare chitinous nanoparticles from black soldier fly (BSF). SFE treatment was performed at a steam pressure of 0.45 to 1.60 MPa with a holding time of 60 s. As the pressure increased, the particle size of the chitinous particles decreased. Under SFE at 1.60 MPa, chitinous nanoparticles with sizes ranging from 59 to 162 nm were produced. SEM, AFM, Raman spectroscopy, FT-IR spectroscopy, ¹H NMR, TGA, and DSC were used to characterize the BSF chitin materials. It was demonstrated that SFE treatment deacetylated chitin to obtain chitosan with 91.24 % deacetylation. In addition, the polymer backbone was maintained, and the degree of polymerization of chitosan nanoparticles was reduced. The activity of the cationic groups of chitosan nanoparticles was improved, thereby enhancing the temperature sensitivity of the polymeric material. It can be concluded that the SFE one-step processing method is a simple and efficient way to prepare homogeneous biomaterial nanoparticles. This study has implications for the development of chitosan nanomaterials for biomedical applications.

Extraction and characterization of waxy and normal barley β-glucans and their effects on waxy and normal barley starch pasting and degradation properties and mash filtration rate

Interactions between β-glucan and starch influence the health benefits of barley-based foods and barley brewing performance. Here, we characterized β-glucans from waxy and normal barley varieties and compared the effects of different β-glucans on the pasting and degradation of waxy and normal barley starches as well as the filterability of mashes from unmalted waxy and normal barley. Waxy barley Zangqing18 β-glucan displayed more compact micrographic features, higher molecular weight, larger particle size, higher thermal decomposition temperature and lower rheological viscosity than normal barley Zangqing2000 β-glucan. β-Glucan not only significantly decreased the pasting viscosities of waxy and normal starches but also lowered the pasting temperatures and peak times of normal starch, likely by inhibiting granule swelling and disrupting the integrity of the continuous phase. β-Glucan also decreased in vitro digestion extent of starch and increased the resistant starch. The unmalted waxy barley had a mash filtration rate much faster than normal barley because starch and β-glucan in waxy barley were rapidly and completely digested and formed more open filter passages. The effects of β-glucan on starch properties varied with the types and contents of β-glucans, whilst the types of starches showed more significant effects. CHEMICAL COMPOUNDS STUDIED: β-Glucan (Pubchem CID: 439262); Amylopectin (Pubchem CID: 439207); Starch (Pubchem CID: 156595876).

Relations between in vitro starch digestibility of commercial baked products and their macronutrients

BACKGROUND

Baked products such as biscuits and breads are the staple foods for a large population, with the starch digestion rate having a crucial effect on human health. Currently, there is a lack of information on general starch digestibility in commercial baked products and its correlation with macronutrient content.

RESULTS

The present study investigated the starch digestibility of 35 commercial baked products, ranging from low to high moisture contents. Biscuits generally had a slower starch digestion rate than mini-breads, whereas breads including whole wheat bread had the fastest digestion rate. Additionally, starch digestibility was negatively correlated with the calorie (R²  = 0.71) and fat content (R²  = 0.56) in per serving size, possibly because of the formation of amylose-lipid complex.

CONCLUSION

The present study provides a database for the in vitro starch digestibility of a large number of food items, which gives general indications on the performance of starch components of commercial products in the human gastrointestinal tract. © 2022 Society of Chemical Industry.

Effect of Heat–Moisture Treatment on the Physicochemical Properties, Structure, Morphology, and Starch Digestibility of Highland Barley (Hordeum vulgare L. var. nudum Hook. f) Flour

This study modified native highland barley (HB) flour by heat–moisture treatment (HMT) at different temperatures (90, 110, and 130 °C) and moisture contents (15%, 25%, and 35%). The effects of the treatment on the pasting, thermal, rheological, structural, and morphological properties of the native and HMT HB flour were evaluated. The results showed that HMT at 90 °C and 25% moisture content induced the highest pasting viscosity (3626–5147 cPa) and final viscosity (3734–5384 cPa). In all conditions HMT increased gelatinization temperature (T_o, 55.77–73.72 °C; T_p, 60.47–80.69 °C; T_c, 66.16–91.71 °C) but decreased gelatinization enthalpy (6.41–0.43 J/g) in the HMT HB flour compared with that in the native HB flour. The HB flour treated at 15% moisture content had a higher storage modulus and loss modulus than native HB flour, indicating that HMT (moisture content, 15%, 25%, and 35%) favored the strengthening of the HB flour gels. X-ray diffraction and Fourier-transform infrared spectroscopy results showed that HMT HB flour retained the characteristics of an A-type crystal structure with an increased orderly structure of starch, while the relative crystallinity could be increased from 28.52% to 41.32%. The aggregation of starch granules and the denaturation of proteins were observed after HMT, with additional breakage of the starch granule surface as the moisture content increased. HMT could increase the resistant starch content from 24.77% to 33.40%, but it also led to an increase in the rapidly digestible starch content to 85.30% with the increase in moisture content and heating temperature. These results might promote the application of HMT technology in modifying HB flour.

Characterization of Volatile Compounds by HS-GC-IMS and Chemical Composition Analysis of Colored Highland Barley Roasted at Different Temperatures

Colored highland barley (CHB) is featured with its potential health-promoting benefits. CHB is frequently processed through roasting, which changes its volatile smells, color, and composition. The objective of this work was to establish the volatile fingerprints of CHB that had been roasted at different temperatures using E-nose and headspace-gas-chromatography-ion-mobility spectroscopy (HS-GC-IMS). The findings showed that roasting increased the relative contents of pyrazines, aldehydes, and ketones while decreasing the relative contents of alcohols, esters, and sulfides. Pyrazines were identified as the markers for volatile substances of the roasted CHB (RCHB). The outcomes of the principal component analysis (PCA) and hierarchical clustering analysis (HCA) demonstrated that the volatiles could easily distinguish between raw CHB and RCHB instead of differentiating between CHB roasted at different temperatures. Additionally, after roasting, the color characteristics and CHB constituents underwent changes, and the effect of roasting temperature on these changes differed depending on the cultivar. Protein, free amino acids, and flavonoids appeared to primarily participate in the variations of volatile substances, and the free fluorescence intermediary compounds might involve changes in color parameters and aromas. These findings improved our knowledge of the volatiles in CHB that were roasted under various conditions.

Effect of steam explosion on nutritional components, physicochemical and rheological properties of brown rice powder

Brown rice powder is underutilized mainly due to its lower starch digestibility and poor processing performance. The present study investigated the potential of steam explosion on the improvement of nutritional and physicochemical characteristic in brown rice powder and rheological property of paste. Compared with native brown rice powder, steam explosion at 0.5 MPa for 7 min increased the water-extractable arabinoxylans (5.77%), reducing sugar content (21.04%), and iodine blue value (30.38%), which indicated steam explosion that destroyed the intact cells of brown rice. Later the crystalline structure of brown rice powder was destroyed into an amorphous structure by steam explosion. Steam explosion enhanced the degree of gelatinization (4.76~351.85%) and solvent retention capacity (SRC) of brown rice powder, compared with native sample. The effect on the intact cells and starch structure of brown rice caused the starch digestibility enhancement remarkable. Viscoelastic profiles confirmed that steam explosion weakened the paste strength and elasticity corresponded with hardness and cohesiveness by increasing the loss factor (tanδ). This work provided important information for brown rice powder modified by steam explosion (0.5 MPa, 7 min) with good nutritional property (nutrients and digestibility) and processability (SRC, textural, and rheological property). Steam exploded brown rice powder (0.5 MPa, 7 min) could serve as a potential ingredient widely used in food products.

Improving bioaccessibility and physicochemical property of blue-grained wholemeal flour by steam explosion

Whole grain contains many health-promoting ingredients, but due to its poor bioaccessibility and processibility, it is not widely accepted by consumers. The steam explosion was exploited to modify the nutritional bioaccessibility and the physicochemical properties of wholemeal flour in this study. In vitro starch digestibility, in vitro protein digestibility of wholemeal flour, total flavonoids content, and total phenolics content of digestive juice were used to evaluate the bioaccessibility, and a significant variation (p < 0.05) was noted. Results showed that steam explosion enhanced the gastric protein digestibility ranged from 5.67 to 6.92% and the intestinal protein digestibility ranged from 16.77 to 49.12%. Steam-exploded wholemeal flour (0.5 MPa, 5 min) had the highest protein digestibility and rapidly digestible starch content. Compared with native flour, steam explosion (0.5 MPa, 5 min) contributed to a 0.72-fold and 0.33-fold increment of total flavonoids content and total phenolics content in digestible juice. Chemical changes of wholemeal flour, induced by steam explosion, caused the changes in the solvent retention capacity, rheological property of wholemeal flour, and altered the falling number (and liquefaction number). An increasing tendency to solid-like behavior and the gel strength of wholemeal flour was significantly enhanced by the steam explosion at 0.5 MPa for 5 min, while the gluten was not weakened. This study indicated that steam-exploded wholemeal flour (0.5 MPa, 5 min) could serve as a potential ingredient with the noticeable bioaccessibility and physicochemical properties in cereal products.

A reference-guided TILLING by amplicon-sequencing platform supports forward and reverse genetics in barley

Barley is a diploid species with a genome smaller than those of other members of the Triticeae tribe, making it an attractive model for genetic studies in Triticeae crops. The recent development of barley genomics has created a need for a high-throughput platform to identify genetically uniform mutants for gene function investigations. In this study, we report an ethyl methanesulfonate (EMS)-mutagenized population consisting of 8525 M₃ lines in the barley landrace "Hatiexi" (HTX), which we complement with a high-quality de novo assembly of a reference genome for this genotype. The mutation rate within the population ranged from 1.51 to 4.09 mutations per megabase, depending on the treatment dosage of EMS and the mutation discrimination platform used for genotype analysis. We implemented a three-dimensional DNA pooling strategy combined with multiplexed amplicon sequencing to create a highly efficient and cost-effective TILLING (targeting induced locus lesion in genomes) platform in barley. Mutations were successfully identified from 72 mixed amplicons within a DNA pool containing 64 individual mutants and from 56 mixed amplicons within a pool containing 144 individuals. We discovered abundant allelic mutants for dozens of genes, including the barley Green Revolution contributor gene Brassinosteroid insensitive 1 (BRI1). As a proof of concept, we rapidly determined the causal gene responsible for a chlorotic mutant by following the MutMap strategy, demonstrating the value of this resource to support forward and reverse genetic studies in barley.

Effect and mechanism of glycerol monostearate dimer (GMS-D) and baking-treatment on the structure, in vitro digestion of gelatinized potato starch-GMS-D

With the increasing progress of society and in-depth scientific research, dietary regulations, especially sustained glucose releases, are regarded as an effective and significant way to lighten or even cut the emergence of diabetes. In this research, the starch-lipid complex gelatinized potato starch-glycerol monostearate dimer (GPS-GMS-D) was developed to provide a low-glycemic index functional food component for type 2 diabetes. Briefly, the higher complexation index (CI, 71.02%), lower rapidly digestible starch (RDS, 35.57%), and lower estimated glycemic index (eGI, 52.34%) were referred to as GPS-GMS-D. It was assumed that the solid V-type crystal structure, induced with the helix between GMS-D and GPS due to high amylose, high saturation, and low steric hindrance, contributed to the lower digestibility. In addition, baking treatment for 5 min was systematically exerted to improve the flavor of GPS-GMS-D with a relatively high CI (59.98%) and low eGI (54.15%). It was believed that rapid dehydration and close interaction during baking treatment could slow down the decomposition of GPS-GMS-D and conversions of starch fractions. Therefore, these results suggested that the as-developed GPS-GMS-D was a promising low GI functional dietary food component for diabetes mellitus, and a suitable baking post-thermal treatment was successfully proposed to enhance the flavor of GPS-GMS-D. PRACTICAL APPLICATION: The higher amylose and solid V-type crystal structure in gelatinized potato starch-glycerol monostearate dimer (GPS-GMS-D) would induce the formation of slowly digestive starch (SDS) and resistant starch (RS) to suppress enzymatic hydrolysis. Moreover, the flavor of GPS-GMS-D was enhanced with appropriate and moderate thermal processing (baking), which was likely to improve the quality of life of a person with diabetes. Thus, we believe that GPS-GMS-D is a promising functional food component for diabetes mellitus.

In Vitro and In Vivo Digestive Fate and Antioxidant Activities of Polyphenols from Hulless Barley: Impact of Various Thermal Processing Methods and β-Glucan

The unfavorable bioaccessibility of polyphenols in cereal-based food limits their physiological functions as most polyphenols bind spontaneously to the cell-wall polysaccharides. Effects of β-glucan and various thermal processing methods including flaking and roasting, stir-frying, steam-flash explosion, and popping expansion on the bioaccessibility and antioxidant properties of polyphenols from hulless barley in vitro and in vivo were investigated in this study. The bioaccessibility and antioxidant capacity (via DPPH, ·OH, and ·O₂^- free radical scavenging, TAC, and FRAP assays) of polyphenol extracts from hulless barley treated by steam-flash explosion and popping expansion increased significantly before and after in vitro digestion compared to those from raw and other processed hulless barley. Further, the total polyphenol content of hulless barley elevated dramatically following hydrolyzing with β-glucanase, which was positively correlated with the antioxidant activity. Additionally, the hulless barley treated with steam-flash explosion exhibited potent antidiabetic effects and antioxidant capacity (via TAC, SOD, GSH-Px, CAT, and MDA assays) in type 2 diabetic rats. The absorption of individual phenolic compounds in the alimentary canal of rats was impacted obviously by thermal processing. This study provides new insights into enhancing the bioaccessibility of the polyphenols and suggests that β-glucans interact with polyphenols and proteins in the hulless barley matrix.

Bioconversion of High-Calorie Potato Starch to Low-Calorie β-Glucan via 3D Printing Using Pleurotus eryngii Mycelia

Edible fungi play an important role in material and energy cycling. This study explored the role of Pleurotus eryngii mycelia in the transformation of potato high-calorie starch to low-calorie β-glucan. First, the 3D printing performance of the potato medium was optimized. After inoculating the fermentation broth of Pleurotus eryngii in 3D printing, we studied the microstructure and material composition of the product. Along with the increase in 3D printing filling ratio, the starch content of the culture product decreased from 84.18% to 60.35%, while the starch content in the solid medium prepared using the mold was 67.74%. The change in β-glucan content in cultured products was opposite to that of starch, and the content of the culture product increased from 12.57% to 24.31%, while the β-glucan content in the solid medium prepared using the mold was 22.17%. The amino acid composition and content of the 3D printing culture system and solid culture products prepared using the mold were similar. The 3D printing culture system promoted the bioconversion efficiency of mycelia. It also showed high application potential of Pleurotus eryngii mycelia for the preparation of low-calorie food.

Possible regulation of liver glycogen structure through the gut-liver axis by resistant starch: a review

Liver glycogen α particles in diabetic patients are fragile relative to those in healthy individuals, and restoring these fragile glycogen particles to a normal state shows potential to contribute to the remission of diabetes. Resistant starch (RS) is beneficial for diabetes management through its interactions with the gut microbiota. However, its effects on glycogen fragility are not fully understood. This review aims to summarize the recent understanding of the interactions between RS and the human gut microbiota and the possible connections to liver glycogen biosynthesis to elucidate its role in the development of glycogen fragility. RS might regulate glycogen fragility in diabetes by modulating the postprandial glycemic response and glycogen biosynthesis pathways. Before RS can be applied to repair fragile glycogen, more work should be done to better understand in vivo RS structures and identify the factor binding glycogen β particles together. This review contains important information on the connections between glycogen fragility and RS-gut microbiota interactions, which could help to better understand the health benefits of RS consumption.

Align resistant starch structures from plant-based foods with human gut microbiome for personalized health promotion

Resistant starch (RS) is beneficial for human health through its interactions with gut microbiota. However, the alignment between RS structures with gut microbiota profile and consequentially health benefits remain elusive. This review summarizes current understanding of RS complex structures and their interactions with the gut microbiota, aiming to highlight the possibility of manipulating RS structures for a targeted and predictable gut microbiota shift for human health in a personalized way. Current definition of RS types is strongly associated with starch digestion behaviors in small intestine, which does not precisely reflect their interactions with human gut microbiota. Distinct alterations of gut microbiota could be associated with the same RS type. The principles to describe the specificity of different RS structural characteristics in terms of aligning with human gut microbiota shift was proposed in this review, which could result in new definitions of RS types from the microbial perspectives. To consider the highly variable personal features, a machine-learning algorithm to integrate different personalized factors and better understand the complex interaction between RS and gut microbiota and its effects on individual health was explained. This review contains important information to bring interactions between RS and gut microbiota to translational practice.