Xylan-cellulose core structure of oat water-extractable β-glucan macromolecule: Insight into interactions and organization of the cell wall complex

Water-extractable β-glucan with high molar mass (HM) determines health benefits of oat food. Oat β-glucan was extracted by a standardized in vitro digestion method and co-existing water-extractable polysaccharide (WEP) fraction and its HM-arabinoxylan (HM-AX) subfraction were isolated to identify their highly acid-resistant subunit and investigate molecular interactions between constituent polymers. The WEP and HM-AX samples consisted of arabinoxylans (AXs) (74 and 76 %, respectively), however, cellulose constituted the secondary component (6.6 and 12.8 %, respectively). Multi-detection HPSEC along with specific enzymatic hydrolysis of AXs revealed the presence of the HM-xylan domain (16 and 34 %, respectively) built of numerous single- and multi-component populations with random coil and rod-like conformations, which were embedded in a xylan matrix with spherical conformation and controlled the macromolecular shape. Unlike single-component populations, the multi-component ones were resistant to hydrolytic action of AX-hydrolyzing enzymes and represented the subunits that anchor matrix polysaccharides onto cellulose surface. These results indicate that water-extractable β-glucan macromolecule comprises as integral element a cellulose core with two linking populations, HM-xylan and low molar mass glucomannan, which are surrounded by a feruloylated AX-arabinan-arabinogalactan composite and next laminated by β-glucan matrix. The stiff cellulose-xylan backbone is the basis of HM β-glucan organization, controlled by its cellulose-like segments.

Dissolving Kraft Pulp Production and Xylooligosaccharide Coproduction: Effect of Pre-Hydrolysis Conditions

Due to cotton's declining sustainability, more lignocellulosic materials are being used to produce dissolving pulp for textile applications. Pre-hydrolysis kraft is one of the main processes used to produce this material. Pre-hydrolysis under conventional conditions removes most of the hemicelluloses, but the majority end up as xylose and furfural, traditionally burned in a recovery boiler. The xylooligosaccharides (XOS), derived from hemicelluloses are a specialty product and can be recovered but requires adapted operative conditions. Thus, the objective was to recover XOS and evaluate the effect of pre-hydrolysis conditions on the final pulp characteristics. A flow-through reactor (FTR) was used to study the pre-hydrolysis, which allowed for modification of the retention time of the xylan in the free liquor after extraction from wood. The results have shown that by changing the fluid retention time in the pre-hydrolysis, the proportion of XOS/xylose/furfural recovered can be strongly changed. The hemicellulose content of the dissolving pulp decreased from 6.8% to about 2.6% using the FTR pretreatment.

Chemical Characterization, Antioxidant, and Antihyperglycemic Capacity of Ferulated Arabinoxylan Extracted from “Chicha de Jora” Bagasse: An Ancestral Fermented Beverage from Zea mays L

Bagasse is a byproduct generated during the process of making the traditional Andean drink named “chicha de jora” in Peru, which is a potential source for the extraction of ferulated arabinoxylan (FAX). The aim of this study was to extract and characterize the FAX from bagasse and determine its antioxidant and antihyperglycemic capacity in vitro. As a result, FAX of molecular weight ≥3.5 kDa presented moisture content, pH, total ash, proteins, and total phenolic content with values of 8.00%, 5.81, 2.68%, 3.78%, and 5.72 mg EAG/g, respectively. Thin-layer chromatography identified the monosaccharides L-arabinose and D-xylose. HPLC-MS/MS analysis of FAX confirmed the presence of methyl-pentofuranosides or methyl-pentopyranosides. The FT-IR spectrum presented characteristic bands of FAX. The FAX showed antioxidant capacity determined by the DPPH assay (IC50 = 6.59 mg/mL and TEAC = 7.7844 μmol/g sample), ABTS (IC50 = 6.50 mg/mL and TEAC 35.34 μmol/g sample), and FRAP (14.08 μmol AA/g and 36.63 μmol FeSO4/g). On the other hand, FAX showed glucose adsorption capacity, inhibition of glucose diffusion, and inhibition of the enzyme α-amylase (IC50 = 4.73 mg/mL). The results showed that the FAX extracted from the bagasse generated during the production of the “chicha de jora” has in vitro antioxidant and antihyperglycemic capacity.

Extraction and characterization of arabinoxylans obtained from nixtamalized brewers' spent grains

The processes to obtain value-added products from brewers' spent grain, a contaminant industrial waste, require alkaline non-ecofriendly pre-treatments. The arabinoxylans from brewers' spent grain were extracted by nixtamalization evaluating the extraction procedure, antioxidant capacity and molecular characteristics. The best arabinoxylans yields were those extracted with CaO at 100°C and 25°C (6.43% and 3.37%, respectively). The antioxidant capacity by 2,2-diphenyl-1-picrylhydrazyl assay of the arabinoxylans after thermal treatment and additional arabinoxylans after thermal treatment proteolysis were 434 and 118 mg TE/g, while by 2,20'-azino-bis (3-ethylbenzothiazoline-6-sulphonic acid) diammonium salt assay the value was similar (380 μmol TE/g). The intrinsic viscosities and viscosimetric molecular weights were 69 mL/g and 13 kDa for arabinoxylans after thermal treatment, and 15 mL/g and 1.6 kDa for arabinoxylans after thermal treatment proteolysis, respectively. The protein and lignin contents were 3.1% and 6.4% for arabinoxylans after thermal treatment and, 0.9% and 4.6% for arabinoxylans after thermal treatment proteolysis, while their arabinose: xylose ratios were 0.39 and 0.36, with ferulic acid contents of 0.63 and 0.14 mg/g, respectively. Both products of arabinoxylans were molecularly identical by Fourier transform infra-red. Although the purity of the extracted arabinoxylans was improved with proteolysis, their intrinsic viscosity and viscosimetric molecular weight were affected. The extraction of arabinoxylans from brewers' spent grain by CaO nixtamalization alone or after additional proteolysis was successful to obtain purity and good antioxidant capacity.

Conformational Behavior, Topographical Features, and Antioxidant Activity of Partly De-Esterified Arabinoxylans

This study aimed to investigate the effect of arabinoxylans (AX) partial de-esterification with feruloyl esterase on the polysaccharide conformational behavior, topographical features, and antioxidant activity. After enzyme treatment, the ferulic acid (FA) content in AX was reduced from 7.30 to 5.48 µg FA/mg polysaccharide, and the molecule registered a small reduction in radius of gyration (RG), hydrodynamic radius (Rh), characteristic ratio (C∞), and persistence length (q). A slight decrease in α and a small increase in K constants in the Mark-Houwink-Sakurada equation for partially de-esterified AX (FAX) suggested a reduction in molecule structural rigidity and a more expanded coil conformation, respectively, in relation to AX. Fourier transform infrared spectroscopy spectra of AX and FAX presented a pattern characteristic for this polysaccharide. Atomic force microscopy topographic analysis of FAX showed a more regular surface without larger hollows in relation to AX. The antioxidant activity of FAX, compared to AX, was reduced by 30 and 41% using both 2,2'-azino-bis (3-ethylbenzothiazoline-6-sulphonic acid) (ABTS+) and 1,1-diphenyl-2-picryl-hydrazyl (DPPH) methods, respectively. These results suggest that feruloyl esterase treatment of AX could offer a strategy to tailor AX chains conformation, morphological features, and antioxidant activity, impacting the development of advanced biomaterials for biomedical and pharmaceutical applications.

Valorization of Heat-Treated Brewers' Spent Grain Through the Identification of Bioactive Phenolics by UPLC-PDA and Evaluation of Their Antioxidant Activities

Thermal processing not only disrupts cell membranes and cell walls, but also cleaves covalent bonds releasing low molecular phenolic. This study examined the impact of various heat treatments (100, 140, and 160°C) on the composition of phenolic acids and antioxidant activities in extracts obtained from defatted brewers spent grain (BSG) meal. Heating BSG at 160°C resulted in a 2-fold increase in total phenolic content [TPC, 172.98 ± 7.3 mg Gallic acid equivalent (GAE)/100 g defatted meal] and total flavonoid content [TFC, 16.15 ± 2.22 catechin equivalents (CE)/100 g defatted meal] compared to the untreated BSG extracts. The antioxidant activities of treated BSG extracts, determined by radical scavenging and ferric reducing antioxidant power (FRAP) were significantly (p < 0.5) higher than the corresponding untreated BSG extracts. Eleven phenolic acids were identified and quantified in BSG extracts by Ultra Performance Liquid Chromatography with Photodiode Array (UPLC-PDA). The amounts varied significantly (p < 0.05) depending on the degree of toasting BSG was subjected to. Chlorogenic acid, an ester of caffeic and quinic acid was the predominant phenolic acid present in all fractions. Significant (p < 0.05) increases in TPC, TFC, individual phenolic acids and antioxidant activity were observed in BSG extracts exposed to increasing oven temperatures. These results confirm the ability of heat processing to release bioactive phenolic from their bound forms thereby enhancing the phenolic acids and the digestibility of BSG meal in the intestinal tract.

Bioactive Compounds and Antioxidant Capacity in Pearling Fractions of Hulled, Partially Hull-Less and Hull-Less Food Barley Genotypes

Three food barley genotypes differing in the presence or absence of husks were sequentially pearled and their fractions analyzed for ash, proteins, bioactive compounds and antioxidant capacity in order to identify potential functional food ingredients. Husks were high in ash, arabinoxylans, procyanidin B3, prodelphinidin B4 and p-coumaric, ferulic and diferulic bound acids, resulting in a high antioxidant capacity. The outermost layers provided a similar content of those bioactive compounds and antioxidant capacity that were high in husks, and also an elevated content of tocols, representing the most valuable source of bioactive compounds. Intermediate layers provided high protein content, β-glucans, tocopherols and such phenolic compounds as catechins and bound hydroxybenzoic acid. The endosperm had very high β-glucan content and relative high levels of catechins and hydroxybenzoic acid. Based on the spatial distribution of the bioactive compounds, the outermost 30% pearling fractions seem the best option to exploit the antioxidant capacity of barley to the full, whereas pearled grains supply β-glucans enriched flours. Current regulations require elimination of inedible husks from human foods. However, due to their high content in bioactive compounds and antioxidant capacity, they should be considered as a valuable material, at least for animal feeds.

Interactive effects of molecular weight and degree of substitution on biological activities of arabinoxylan and its hydrolysates from triticale bran

Arabinoxylan (AX) has many beneficial health effects that are closely related to its structural characteristics. The current study aimed to investigate the effects of molecular weight (Mw) and degree of substitution (DS) on the antioxidant and hypoglycemic activities of triticale bran AX and its hydrolysates in vitro. At low and similar Mw, the antioxidant activity of AX was inversely proportional to its DS. When DS was close, the antioxidant activity of AX was inversely proportional to its Mw at high DS, but the opposite result was found at low DS. As for the hypoglycemic performance, when DS was similar, the hypoglycemic activity of AX was proportional to its Mw. At low and similar Mw, the α-glucosidase inhibitory ability and glucose adsorption ability of AX was positively correlated with DS, whereas the α-amylase inhibitory ability and glucose delayed absorption ability showed the opposite results. Mw and DS had significant effects on the antioxidant and hypoglycemic activities of AX, and these two factors often need to be combined to explain the varied effects under different conditions.

Optimisation of double-enzymatic extraction of arabinoxylan from fresh corn fibre

Enzymatic extraction of arabinoxylans (AXs) is an attractive and environmentally friendly extraction option, in which technical considerations (yield and purity) have been coupled with environmental concerns. Amano HC 90 and Cellulase were combined to evaluate their interactive effects on AX extraction from destarched, deproteinised bran (DSDPB). A response surface methodology was used to obtain the optimal extraction conditions. The experimental data fit well with the predicted values and the model adequately represented the actual relationship among the measured parameters. The extraction yield and AX content in the extract under optimal conditions (double-enzyme dose of 920 U/g, pH of 3.0, extraction temperature of 35.0 °C; extraction time of 6 h; and DSDPB to liquid ratio of 1:30) were 40.73 ± 0.09% and 75.88 ± 0.11%, respectively. The double-enzymatic extraction method of AX from fresh corn fibre was more efficient than the chemical method.

Distribution of free and bound phenolic compounds, and alkylresorcinols in wheat aleurone enriched fractions

Several companies have focused their attention on the development of technologies able to enrich/isolate the wheat aleuronic layer because it is a source of bioactive compounds. In this work two different wheat bran fractions enriched in aleurone (AF1, 55-70% aleurone and AF2, 75-90% aleurone) were obtained by a dry fractionation based on air classification. Free and bound phenolic compounds, and alkylresorcinols were determined in the two fractions by HPLC-DAD-ESI-TOF-MS and GC-MS, respectively. To our knowledge, feruloyl di-hexoside was described for the first time in wheat aleurone and flavonoids were quantified for the first time in this fraction. The results have shown that the most concentrated free phenolic compounds were flavonoids, and AF1 was the fraction that presented the highest flavonoid content; whereas trans ferulic acid was the most abundant bound phenolic acid, which highest content was obtained in AF2. Besides, total content of ferulic acid monomers in AF2 was 33.63% higher than in AF1, whereas total content of ferulic acid dimers/trimers in AF1 was 33.9% higher than in AF2. The highest content of alkylresorcinols was obtained in AF1 and it was 10.30% higher than the obtained in AF2. Therefore, it can be stated that this green technology could be used to produce enriched aleurone fractions as source of phenolic and alkylresorcinol compounds. These fractions could be of great interest for the formulation of enriched foods.

Advances on the Valorisation and Functionalization of By-Products and Wastes from Cereal-Based Processing Industry

Cereals have been one of the major food resources for human diets and animal feed for thousands of years, and a large quantity of by-products is generated throughout the entire processing food chain, from farm to fork. These by-products mostly consist of the germ and outer layers (bran) derived from dry and wet milling of the grains, of the brewers' spent grain generated in the brewing industry, or comprise other types obtained from the breadmaking and starch production industries. Cereal processing by-products are an excellent low-cost source of various compounds such as dietary fibres, proteins, carbohydrates and sugars, minerals and antioxidants (such as polyphenols and vitamins), among others. Often, they are downgraded and end up as waste or, in the best case, are used as animal feed or fertilizers. With the increase in world population coupled with the growing awareness about environmental sustainability and healthy life-styles and well-being, the interest of the industry and the global market to provide novel, sustainable and innovative solutions for the management of cereal-based by-products is also growing rapidly. In that respect, these promising materials can be valorised by applying various biotechnological techniques, thus leading to numerous economic and environmental advantages as well as important opportunities towards new product development (NPD) in the food and feed industry and other types such as chemical, packaging, nutraceutical (dietary supplements and food additives), cosmetic and pharmaceutical industries. This review aims at giving a scientific overview of the potential and the latest advances on the valorisation of cereal-based by-products and wastes. We intended it to be a reference document for scientists, technicians and all those chasing new research topics and opportunities to explore cereal-based by-products through a circular economy approach.

Production and characterization of functional wheat bran hydrolysate rich in reducing sugars, xylooligosaccharides and phenolic acids

The aim was to enhance production of functional hydrolysate from wheat bran (WB). WB was hydrolyzed with 3000 U/mL ɑ-amylase and 1200 U/mL alkaline protease to prepare WB insoluble dietary fibre (WBIDF). Functional hydrolysate production from the extract containing crude xylan of WBIDF by xylanase was optimized by Taguchi method. The optimal condition for xylan degradation and functional substances production was 78.50 U/mL xylanase, pH 10.0, 50 °C, and reaction time 6 h. The maximum yield of reducing sugars was 614.0 μg/mL, xylobiose increased from 12.9 μg/mL to 213.3 μg/mL, xylotriose increased from 34.9 μg/mL to 174.0 μg/mL, ferulic acid 13.1 μg/mL made up 57.5 % of the total identifiable phenolic pool in the hydrolysate. The total antioxidant activity of hydrolysate was 141.8 mg ascorbic acid equivalents g^-1 crude xylan, and the highest 1,1-diphenyl-2-picrylhydrazyl (DPPH) radical scavenging activity reached 92.7 %. The hydrolysate exhibited great potential in agricultural and food industry application.

Structural modifications to water-soluble wheat bran arabinoxylan through milling and extrusion

Feruloylated arabinoxylan (AX) is one of the most predominant dietary fiber in cereal grains. In recent decades, soluble AX has gained interest, as a result of its well-established health benefits. Apart from enzymatic degradation during cereal storage, food processing causes AX degradation. These reactions lead to structural modifications and influence both the AX functionalities and its health promoting effects. The aim of this study was to investigate the structural modifications and related property changes of health promoting water-extractable (WE) wheat bran AX through grain milling and extrusion. Multi-detector HPSEC revealed a correlation between M_w, conformational changes and the related viscosity behaviour depending on the processing type. Processing caused molecular degradation of insoluble high M_w AX, which increased the solubility significantly. Moreover, extrusion leaded to a more heterogenic AX fine structure. The detailed characterization of processed dietary fiber may help to facilitate the optimized incorporation of AX in health-promoting foods.

Phenolic Acids, Antioxidant Capacity, and Estimated Glycemic Index of Cookies Added with Brewer's Spent Grain

Brewers' spent grain (BSG) is the major by-product of the brewing industry, with great potential as a functional ingredient due to its bioactive compounds. Thus, BSG could be suitable for improving the low nutritional quality of wheat-based snacks highly consumed by young people. The objective of this study was to substitute wheat flour with BSG (0, 10, 20, and 30%) for cookies elaboration, and evaluate the dough rheology, phenolic acids, antioxidant capacity, arabinoxylans content and proximate composition of the cookies Protein content and bioactive compounds (ferulic and p-coumaric acids, water unextractable arabinoxylans) of cookies significantly (p < 0.05) increased with the substitution level. In comparison to the wheat-alone cookies, the 20% BSG-containing cookies showed a lower hydrolysis and glycemic index (GI), and less total starch. The low cost, protein-rich BSG with antioxidant capacity improves the nutritional quality of cookies and may confer health benefits beyond basic nutrition.

Effect of Ultrasound-Treated Arabinoxylans on the Oxidative Stability of Soybean Oil

Arabinoxylans (AX) are polysaccharides with antioxidant activity and emulsifying properties, which make them an attractive alternative for its potential application as a natural antioxidant in oils. Therefore, this work aimed to investigate the effect of ultrasonic treatment of AX on their antioxidant capacity and its ability to improve the oxidative stability of soybean oil. For this purpose, AX were exposed to ultrasonic treatment at 25% (100 W, AX-1) and 50% (200 W, AX-2) power and an operating frequency of 20 KHz during 15 min, and their macromolecular properties (weight average molecular weight (Mw), polydispersity index and intrinsic viscosity) were evaluated. The antioxidant capacity of AX was determined by the DPPH assay and Rancimat test. Results showed that ultrasonic treatment did not affect the molecular identity of the polysaccharide but modified its Mw distribution. AX-1 showed the highest antioxidant activity (75% inhibition) at 533 µg/mL by the DPPH method compared to AX and AX-2. AX at 0.25% (w/v) and AX-1 at 0.01% (w/v) exerted the highest protective effects on oxidative stability of soybean oil with induction periods of 7.69 and 5.54 h, respectively. The results indicate that AX could be a good alternative for the potential application as a natural antioxidant in oils.

Feruloylated Arabinoxylans from Maize Distiller’s Dried Grains with Solubles: Effect of Feruloyl Esterase on their Macromolecular Characteristics, Gelling, and Antioxidant Properties

Distiller’s dried grains with solubles (DDGS) are co-products of the maize ethanol industry. DDGS contains feruloylated arabinoxylans (AXs), which can present gelling, antioxidant, and health-promoting effects. However, AXs presenting high ferulic acid (FA) content can exhibit delayed fermentation by the colonic microbiota. Therefore, partial deferuloylation of AXs from DDGS while preserving the polysaccharide gelling and antioxidant properties could add value and favor the sustainable development of bioethanol plants. The aim of this work was to partially deferuloylated AXs from DDGS using feruloyl esterase and to evaluate the polysaccharide macromolecular characteristics, gelling, and antioxidant properties. The AXs presented FA and FA dimer contents of 3.27 and 0.30 µg/mg polysaccharide, respectively, which decreased to 1.26 and 0.20 µg/mg polysaccharide, respectively, in feruloyl esterase-treated AXs (FAXs). The molecular weight and intrinsic viscosity of FAXs were slightly less than those of AXs. The Fourier transform infrared spectroscopy data of AXs and FAXs were similar, confirming that the enzyme did not modify the polysaccharide molecular identity. FAX gels (2% w/v) exhibited a decrease in elasticity by 43% in relation to that of AXs gels. The antioxidant capacity of FAXs was reduced by 32% and 43% (DPPH and ABTS method, respectively), compared with that of AXs. The FAX gelling and antioxidant properties were -comparable to those reported for other AXs in the literature. Feruloyl esterase may offer an interesting approach for the design of functional FAXs as value-added products recovered from DDGS.

Arabinoxylan-Based Particles: In Vitro Antioxidant Capacity and Cytotoxicity on a Human Colon Cell Line

Background and objectives: Arabinoxylans (AX) can gel and exhibit antioxidant capacity. Previous studies have demonstrated the potential application of AX microspheres as colon-targeted drug carriers. However, the cytotoxicity of AX gels has not been investigated so far. Therefore, the aim of the present study was to prepare AX-based particles (AXM) by coaxial electrospraying method and to investigate their antioxidant potential and cytotoxicity on human colon cells. Materials and Methods: The gelation of AX was studied by monitoring the storage (G') and loss (G'') moduli. The morphology of AXM was evaluated using optical and scanning electron microscopy (SEM). The in vitro antioxidant activity of AX before and after gelation was measured using the 2,2'-azino-bis(3-ethylbenzothiazoline-6-sulfonic acid) (ABTS+), 2,2-diphenyl-1-picrylhydrazyl (DPPH) and ferric reducing antioxidant power (FRAP) methods. In addition, the effect of AX and AXM on the proliferation of human colon cells (CCD 841 CoN) was evaluated using the 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT) assay. Results: The final G' and G'' values for AX gels were 293 and 0.31 Pa, respectively. AXM presented spherical shape and rough surface with a three-dimensional and porous network. The swelling ratio and mesh size of AXM were 35 g water/g AX and 27 nm, respectively. Gelation decreased the antioxidant activity of AX by 61-64 %. AX and AXM did not affect proliferation or show any toxic effect on the normal human colon cell line CCD 841 CoN. Conclusion: The results indicate that AXM could be promising biocompatible materials with antioxidant activity.

Structural analysis and antioxidant activity of an arabinoxylan from Malvastrum coromandelianum L. (Garcke)

The structure of MAP was studied by degradative, derivatization and spectroscopic methods, and it was found to be an arabinoxylan comprising a backbone of →4)-β-d-linked Xylp(1→ with branching at O-2 by →3)-α-l-Araf(1→ and →3)-β-d-Xylp(1→ chains.

Understanding the structural and functional properties of carbohydrate esterases with a special focus on hemicellulose deacetylating acetyl xylan esterases

Acetyl and methyl esterifications are two major naturally found substitutions in the plant cell-wall polysaccharides. The non-cellulosic plant cell-wall polysaccharides such as pectin and hemicellulose are differentially esterified by the O-acetyl and methyl groups to cease the action of various hydrolytic enzymes secreted by different fungi and bacterial species. Thus, microorganisms have emerged with a special class of enzymes known as carbohydrate esterases (CE). The CE catalyse O-de, N-deacetylation of acetylated saccharide residues (esters or amides, where sugars play the role of alcohol/amine/acid). Carbohydrate active enzyme (CAZy) database has classified CE into 16 classes, of which hemicellulose deacetylating CE were grouped into eight classes (CE-1 to CE-7 and CE-16). Various plant biomass degrading fungi and bacteria secretes acetyl xylan esterases (AcXE); however, these enzymes exhibit varied substrate specificities. AcXE and xylanases-coupled pretreatment methods exhibit significant applications, such as enhancing animal feedstock, baking industry, production of food additives, paper and pulp, xylitol production and biorefinery-based industries, respectively. Thus, understanding the structural and functional properties of acetyl xylan esterase will significantly aid in developing the efficient AcXE with wide range of industrial applications.

Arabinoxylans from rice bran and wheat immunomodulatory potentials: a review article

Purpose

The purpose of this study is to discuss recent research on arabinoxylans from rice bran and wheat byproducts and their immunomodulatory potentials. Also, a potential receptor for arabinoxylans is proposed in relation to arabinoxylans structure.

Design/methodology/approach

This review summarises recent publications on arabinoxylans from rice bran and wheat, classification of arabinoxylans, a brief background on their method of extraction and their immunomodulatory potentials as they induce pro-inflammatory response in vitro, in vivo and in humans. The mechanism of action in which arabinoxylans modulate the immune activity is yet to be discovered, However, the authors have proposed a potential receptor for arabinoxylans in relation to arabinoxylans structure and molecular weight.

Findings

The effects of arabinoxylans from rice bran and wheat on the immune response was found to cause a pro-inflammatory response in vitro, in vivo and in humans. Also, the immune response depends on arabinoxylans structure, the degree of branching and origin.

Originality/value

This review paper focuses on the effects of arabinoxylans from rice bran and wheat on immunomodulatory potentials in vitro, in vivo and in humans. A new mechanism of action has been proposed based on the literature and via linking between arabinoxylans and lipopolysaccharide structure, molecular weight and suggested proposed receptor, which might be activated via both of them.

Arabinoxylan activates lipid catabolism and alleviates liver damage in rats induced by high-fat diet

BACKGROUND

Arabinoxylan was thought to have the potential to change lipid metabolism and redox homeostasis in human and animal. However, the effect of arabinoxylan on the liver damage induced by high-fat diet needs further exploiting.

RESULTS

Six-weeks-old 30 male Sprague-Dawley Rats were assigned randomly to three groups (n = 10 per group), i.e. a control diet (CON) group, a high-fat diet (HF) group and a high-fat diet supplemented with arabinoxylan (6% AX, HF-AX) group. Results showed that final body weight and liver weight were similar in CON group and HF-AX group, but higher in the HF group. In serum, the HF-AX group showed lower triglyceride concentrations than did the HF group. In liver, higher lipoprotein lipase, hepatic lipase, total lipase, and acyl-CoA oxidase activities and lower triglyceride and cholesterol level were observed in the HF-AX group than in the HF group. For the redox homeostasis, arabinoxylan supplemented in HF increased T-SOD activity and GSH-PX activity and reduced MDA + 4-HNE level in liver and/or compared with those in the HF group. Lipid droplets and liver cell damage were observed in the HF group compared with the CON and HF-AX groups.

CONCLUSION

Arabinoxylan could improve lipid metabolic disorder and alleviate liver damage in rats induced by high-fat diet via activating lipid catabolism and suppressing lipid peroxidation. © 2017 Society of Chemical Industry.

Health-related effects and improving extractability of cereal arabinoxylans

Arabinoxylans (AXs) are major dietary fibers. They are composed of backbone chains of β-(1-4)-linked xylose residues to which α-l-arabinose are linked in the second and/or third carbon positions. Recently, AXs have attracted a great deal of attention because of their biological activities such as their immunomodulatory potential. Extraction of AXs has some difficulties; therefore, various methods have been used to increase the extractability of AXs with varying degrees of success, such as alkaline, enzymatic, mechanical extraction. However, some of these treatments have been reported to be either expensive, such as enzymatic treatments, or produce hazardous wastes and are non-environmentally friendly, such as alkaline treatments. On the other hand, mechanical assisted extraction, especially extrusion cooking, is an innovative pre-treatment that has been used to increase the solubility of AXs. The aim of the current review article is to point out the health-related effects and to discuss the current research on the extraction methods of AXs.

Influence of heat and moisture treatment on carotenoids, phenolic content, and antioxidant capacity of orange maize flour

The aim of this work was to study the effect of heat and moisture treatment (HMT) on carotenoids, phenolic content and antioxidant capacity of ground, orange maize. Total carotenoid content (TCC) of untreated sample (53.39 mg/kg) was 2.2 times higher than measured in treated orange maize f (24.61 mg/kg). The rates of degradation with HMT were in the following order: β-carotene > β-cryptoxanthin > zeaxanthin > lutein. There was a significant interaction between longer heating time and higher moisture content on carotenoid degradation (p < .05). Total phenolic content (TPC) in raw sample (1664.74 mg/kg) was two-fold higher than in treated orange maize (827.89 mg/kg). Ferulic acid was the most abundant and stable phenolic acid in raw and treated orange maize. The antioxidant capacity of orange maize was higher in methanol than in butanol extracts. The highest correlation (0.924) was observed between TPC and ABTS+ scavenging capacity of methanol extracts.

Isolation and identification of feruloylated arabinoxylan mono- and oligosaccharides from undigested and digested maize and wheat

Feruloylated arabinoxylan mono- and oligosaccharides (F-AXOS) are a subject of interest because of their prebiotic and antioxidant properties. We aimed at isolating and identifying F-AXOS from maize, wheat, wheat bran and wheat aleurone using HPLC and LC-MS/MS. Prior to extraction of F-AXOS, samples were subjected to either simulated gastric fluid with enzymes (gastric) or without enzymes (pH) or water (aqueous) at 37 °C. F-AXOS present in all samples were identified as 5-O-feruloyl-α-L- arabinofuranose and possibly 5-O-feruloyl-α-L-arabinofuranosyl-(1 → 3)-O-β-D-xylopyranose. Their mean content, measured as esterified ferulic acid (FA), was 2.5 times higher in maize (10.33 ± 2.40 μg/g) compared to wheat. Digestion under gastric or pH conditions resulted in a two-fold increase in F-AXOS in all samples. The level of F-AXOS produced during gastric or pH condition was positively correlated to the insoluble bound FA content of the sample (R(2) = 0.98). 5-O-Feruloyl-α-L- arabinofuranose was the only identifiable F-AXOS released during gastric digestion. Our results suggest feruloyl arabinose is the most abundant form of F-AXOS in maize and wheat.

Inhibition of Intestinal α-Glucosidase and Glucose Absorption by Feruloylated Arabinoxylan Mono- and Oligosaccharides from Corn Bran and Wheat Aleurone

The effect of feruloylated arabinoxylan mono- and oligosaccharides (FAXmo) on mammalian α-glucosidase and glucose transporters was investigated using human Caco-2 cells, rat intestinal acetone powder, and Xenopus laevis oocytes. The isolated FAXmo from wheat aleurone and corn bran were identified to have degree of polymerization (DP) of 4 and 1, respectively, by HPLC-MS. Both FAXmo extracts were effective inhibitors of sucrase and maltase functions of the α-glucosidase. The IC50 for FAXmo extracts on Caco-2 cells and rat intestinal α-glucosidase was 1.03–1.65 mg/mL and 2.6–6.5 mg/mL, respectively. Similarly, glucose uptake in Caco-2 cells was inhibited up to 40%. The inhibitory effect of FAXmo was dependent on their ferulic acid (FA) content (R = 0.95). Sodium independent glucose transporter 2 (GLUT2) activity was completely inhibited by FAXmo in oocytes injected to express GLUT2. Our results suggest that ferulic acid and feruloylated arabinoxylan mono-/oligosaccharides have potential for use in diabetes management.

Antioxidant properties of diverse cereal grains: A review on in vitro and in vivo studies

Cereal grains and products have gained popularity in contributing to healthy eating behavior because of their antioxidant properties associated with protection against chronic diseases. In this review, notable studies on the in vitro and in vivo antioxidant activity of commonly consumed cereal grains are summarized. Cereals contain phytochemicals or certain minor components with antioxidant properties. The antioxidant potential of cereals depends on their bioaccessibility, absorption in the gastrointestinal and their bioavailability utilization in vivo. The in vitro gastrointestinal digestion and fermentation of cereals increased their antioxidant potentials which are significantly correlated with their total phenolic contents. Most studies performed in vivo have been concerned with the antioxidant properties of colored rice, wheat bran and rye products. There are inadequate in vitro and in vivo studies on antioxidative potentials of fermented versus unfermented cereals. Therefore, further studies are necessary to maximize possible health benefits of cereal antioxidative phytochemicals.