Yellow mustard gum: pilot-scale production and characterization.

BACKGROUND: Yellow mustard gum (YMG), which is extracted from the mucilaginous part of yellow mustard bran, has been considered an emerging natural hydrocolloid gum but lacks commercial development and production. To promote the commercial utilization of YMG, this study developed a pilot-scale YMG production protocol in an economic and environmentally friendly way to produce a clean-label YMG product. This YMG produced at pilot scale (YMW) was characterized in terms of chemical composition, rheological properties, and interaction with a commercial gum, κ-carrageenan, and was compared with purified YMG through ethanol precipitation (YME). RESULTS: The protocol processed up to 100 L of raw material with zero solvent and a minimal number of steps and showed strong quasi-industrial potential. The YMW showed a similar chemical composition as YME. However, the YMW contained a slightly lower amount of carbohydrate and a much larger amount of ash and potassium than the YME. The rheological results concluded that both the YMW and YME solutions exhibited shear-thinning flow behavior and a weak gel, with YME showing higher viscosity and stronger gel structure. Most interestingly, YMW could form unpourable gels when blended with native κ-carrageenan whereas YME barely achieved this despite the equivalent total gum concentration. CONCLUSION: This study demonstrated the feasibility of YMG production at a large scale with economic and green procedures and discovered its new functionality for commercial utilization. The gelling ability of YMG could provide it with wider applications as a result of a new potential synergistic combination. All this information should accelerate the process of full commercialization of YMG as a clean-label functional ingredient. © 2024 His Majesty the King in Right of Canada. Journal of The Science of Food and Agriculture © 2024 Society of Chemical Industry. Reproduced with the permission of the Minister of Agriculture and Agri-Food Canada.

Therapeutic potential of non-starch polysaccharides on type 2 diabetes: from hypoglycemic mechanism to clinical trials.

Non-starch polysaccharides (NSPs) have been reported to exert therapeutic potential on managing type 2 diabetes mellitus (T2DM). Various mechanisms have been proposed; however, several studies have not considered the correlations between the anti-T2DM activity of NSPs and their molecular structure. Moreover, the current understanding of the role of NSPs in T2DM treatment is mainly based on in vitro and in vivo data, and more human clinical trials are required to verify the actual efficacy in treating T2DM. The related anti-T2DM mechanisms of NSPs, including regulating insulin action, promoting glucose metabolism and regulating postprandial blood glucose level, anti-inflammatory and regulating gut microbiota (GM), are reviewed. The structure-function relationships are summarized, and the relationships between NSPs structure and anti-T2DM activity from clinical trials are highlighted. The development of anti-T2DM medication or dietary supplements of NSPs could be promoted with an in-depth understanding of the multiple regulatory effects in the treatment/intervention of T2DM.

Role of Amino Acids in Blood Glucose Changes in Young Adults Consuming Cereal with Milks Varying in Casein and Whey Concentrations and Their Ratio.

BACKGROUND: Increasing the total protein content and reducing the casein to whey ratio in milks consumed with breakfast cereal reduce postprandial blood glucose (BG). OBJECTIVES: We aimed to explore associations between plasma amino acids (AAs), BG, and glucoregulatory hormones. METHODS: In this repeated-measures design, 12 healthy adults consumed cereal (58 g) and milks (250 mL) with 3.1 wt% or high 9.3 wt% protein concentrations and with casein to whey ratios of either 80:20 or 40:60. Blood was collected at 0, 30, 60, 120, 140, 170, and 200 min for measurement of the primary outcome, BG, and for the exploratory outcomes such as plasma AA, gastric emptying, insulin (INS), and glucoregulatory hormones. Measures were made prior to and after an ad libitum lunch at 120 min. Exploratory correlations were conducted to determine associations between outcomes. RESULTS: Pre-lunch plasma AA groups [total (TAA), essential (EAA), BCAA, and nonessential (NEAA)] were higher after 9.3 wt% than 3.1 wt% milks by 12.7%, 21.4%, 20.9%, and 7.6%, respectively (P ≤ 0.05), while post-lunch AA groups were higher by 10.9%, 19.8%, 18.8%, and 6.0%, respectively (P ≤ 0.05). Except for NEAA, pre-lunch AAs were higher after 40:60 than 80:20 ratio milks by 4.5%, 8.3%, and 9.3% (P ≤ 0.05). When pooled by all treatments, pre-lunch AA groups associated negatively with BG (r/ρ ≥ -0.45, P ≤ 0.05), but post-lunch only TAA and NEAA correlated (r ≥ -0.37, P < 0.05). Pre-lunch BG was inversely associated with Leu, Ile, Lys, Met, Thr, Cys-Cys, Asn, and Gln (r/ρ ≥ -0.46, P ≤ 0.05), but post-lunch, only with Thr, Ala, and Gly (r ≥ -0.50, P ≤ 0.05). Pre-lunch associations between AA groups and INS were not found. CONCLUSIONS: Protein concentration and the ratio of casein to whey in milks consumed at breakfast with cereal affect plasma AA concentrations and their associations with decreased BG. The decrease in BG could be explained by INS-independent mechanisms. This trial was registered at www.clinicaltrials.gov as NCT02471092.

Interfacial Activity and Self-Assembly Behavior of Dissolved and Granular Octenyl Succinate Anhydride Starches.

The mechanisms of granular octenyl succinate anhydride (GOSA) and dissolved OSA (DOSA) starches in emulsion stabilization were investigated. In general, DOSA starch offered better emulsification activity by generating greater ζ-potential, lower particle size as well as long-term stability in comparison to GOSA starch of close degree of substitution (DS). A compact interface in DOSA starches was determined, resulting from an increased surface loading value of 2.37 mg/m2 in comparison to that of GOSA of 1.6 mg/m2. Additionally, the irreversibly adsorbed and predominantly elastic interface of both DOSA and GOSA starches indicated that the DOSA starch may be a Pickering emulsifier rather than a biopolymer surfactant. This assumption was confirmed by transmission electron microscopy. Spherical micelles with average diameters of 100 nm were observed above the critical micelle concentration of 1 mg/mL. Moreover, samples G28 (representing DS of 0.028), D28, G16, and D16 could reach equilibrium interfacial tensions of 19.4, 16.5, 20.0, and 19.3 mN/m, respectively. However, due to the misleading contact angle as a result of rough surfaces and nonignorable gravity of GOSA starch, the energy escape equation failed to be employed in this study.

Increased milk protein content and whey-to-casein ratio in milk served with breakfast cereal reduce postprandial glycemia in healthy adults: An examination of mechanisms of action.

This study describes the effects on glycemic response and the underlying mechanisms of action of increasing the protein concentration and decreasing the casein-to-whey ratio in milk when consumed with a high glycemic breakfast cereal. Twelve healthy men and women, aged 18 to 30 yr and with a body mass index of 20 to 24.9 kg/m2, consumed (in random order) milk beverages (250 mL) containing either 3.1 or 9.3% protein and casein-to-whey ratios of either 80:20 or 40:60. We measured postprandial appetite, glucose, regulatory hormones, and stomach emptying rate over 200 min, as well as food intake at an ad libitum meal at 120 min. Although pre-meal appetite was suppressed to a greater extent with milk beverages that had high (9.3%) compared with regular (3.1%) protein content, food intake was similar among all 4 treatments. Pre-meal mean blood glucose was lower with beverages that had high rather than regular milk protein content, with the lowest glucose peaks after the high milk protein treatment with the 40:60 casein-to-whey ratio. Pre-meal insulin and C-peptide levels were not affected by milk protein content or casein-to-whey ratio, but pre-meal glucagon-like peptide 1 was higher after the treatment containing high milk protein and the 40:60 casein-to-whey ratio, and pre-meal cholecystokinin was higher after the treatments containing high milk protein content. Plasma paracetamol response was also lower after the treatments containing high compared with regular milk protein content. When consumed with carbohydrate, milk beverages with high protein content and (to a lesser extent) a decreased casein-to-whey ratio lowered postprandial glycemia through insulin-independent mechanisms, primarily associated with delayed stomach emptying.

Effect of milk protein intake and casein-to-whey ratio in breakfast meals on postprandial glucose, satiety ratings, and subsequent meal intake.

Whey and casein proteins differentially affect postprandial blood glucose and satiety mechanisms, with relevance for type 2 diabetes and obesity. Therefore, the purpose of this work was to investigate the effect of the casein-to-whey protein ratio and total protein concentration of milks consumed with cereal on postprandial blood glucose, appetite ratings, and subsequent food intake in a randomized, controlled, double-blinded study with healthy young adults (n = 32, 23.4 ± 3.1 yr, body mass index = 22.2 ± 2.5 kg/m2). Fasted participants consumed milk (250 mL) with either 80:20 or 40:60 (modified) casein-to-whey protein ratios at commercially normal (3.1%, wt) or high protein (9.3%, wt) concentration, or control (water with whey permeate), each along with 2 servings of oat-based breakfast cereal. Blood glucose concentrations were determined from finger prick blood samples and appetite was assessed using visual analog scales. Participants consumed a measured ad libitum pizza lunch at 120 min and blood glucose determination and appetite assessment continued following the lunch meal (140-200 min) to observe the second meal effect. Pre-lunch (0-120 min) incremental area under the curve (iAUC) and mean change from baseline blood glucose were reduced with consumption of all milk treatments relative to control. However, we found no differences between all treatments on pre-lunch appetite change from baseline and total area under the curve (tAUC) or lunch meal food intake. In terms of protein concentration results, high protein (9.3%, wt) treatments contrasted to normal protein (3.1%, wt) treatments lowered blood glucose change from baseline and iAUC, and post-lunch appetite change from baseline and tAUC. Protein ratio showed a modest effect in that modified (40:60) protein ratio lowered pre-lunch blood glucose change from baseline but not iAUC, and normal (80:20) protein ratio lowered pre-lunch appetite change from baseline but not tAUC. Therefore, high-carbohydrate breakfast meals with increased protein concentration (9.3%, wt) could be a dietary strategy for the attenuation of blood glucose and improved satiety ratings after the second meal.

The role of alginates in regulation of food intake and glycemia: a gastroenterological perspective.

Regulation of food intake through modulation of gastrointestinal responses to ingested foods is an ever-growing component of the therapeutic approaches targeting the obesity epidemic. Alginates, viscous and gel-forming soluble fibers isolated from the cell wall of brown seaweeds and some bacteria, are recently receiving considerable attention because of their potential role in satiation, satiety, and food intake regulation in the short term. Enhancement of gastric distension, delay of gastric emptying, and attenuation of postprandial glucose responses may constitute the basis of their physiological benefits. Offering physical, chemical, sensorial, and physiological advantages over other viscous and gel-forming fibers, alginates constitute promising functional food ingredients for the food industry. Therefore, the current review explores the role of alginates in food intake and glycemic regulation, their underlying modes of action and their potential in food applications.

Preparation of liquid yogurt in the presence of pectin and its formation mechanism.

We had previously observed that adding pectin into milk before fermentation inhibited gelation of yogurt but did not affect the pH. Thus, this work aimed to prepare such liquid yogurt and clarify its formation mechanism. It was found that liquid yogurt was obtained in the presence of 0.10%-0.20% pectin. However, at lower or higher pectin concentrations, yogurt was gelled. Confocal laser scanning microscopy analysis demonstrated that 0.10%-0.20% pectin induced milk protein aggregating into separated particles rather than a continuous network, which explained why liquid yogurt was formed. Moreover, adding 0.10%-0.20% pectin into the casein micelle suspension induced aggregation of casein micelles at pH 6.8. After pH decreased to 4.3, casein micelles showed more aggregation but they were still separated particles, which was the same in the corresponding yogurt samples. These results suggested that pectin changed the aggregation mode of casein micelles and induced formation of liquid yogurt.

Enhanced hypoglycemic effects of konjac glucomannan combined with Polygonatum cyrtonema Hua polysaccharide in complete nutritional liquid diet fed type 2 diabetes mice.

In our aging society, dysphagia and malnutrition are growing concerns, necessitating intervention. Liquid nutrition support offers a practical solution for traditional dietary issues, but it raises a key issue: the potential for post-meal glucose spikes impacting efficacy. This study examined the effects of supplementation of Polygonatum cyrtonema Hua polysaccharide (PCP), konjac glucomannan (KGM) and their combination on acute phase postprandial glycemic response and long-term glucose metabolism in T2DM mice on a complete nutritional liquid diet. KGM was more effective in reducing postprandial glucose response, while PCP was more prominent in ameliorating long-term glucose metabolism. The KGM-PCP combination demonstrated superior outcomes in fasting blood glucose, insulin, and glucose homeostasis. PCP and KGM also influenced the composition and abundance of the gut microbiome, with the H-PCP group showing optimal performance. Moreover, the KGM-PCP combination improved body weight, lipid homeostasis, and liver health the most. PCP potentially regulates glycemia through metabolic pathways, while KGM improves glycemic metabolism by reducing postprandial glucose levels in response to viscous intestinal contents. This research identifies the structure, viscosity properties, and hypoglycemic effects of KGM and PCP in complete nutritional liquid diet fed T2DM mice, enabling their strategic utilization as hypoglycemic components in nutritional administration and glycemic regulation.

Effects of soy-soluble fiber and flaxseed gum on the glycemic and insulinemic responses to glucose solutions and dairy products in healthy adult males.

OBJECTIVE: Soy-soluble polysaccharides and flaxseed gum are underutilized dietary fibers of interest to the food industry. However, because the ability of soluble fibers to modulate postprandial glucose and insulin metabolism has been related to their viscous effects, the utility of these and other low-viscosity soluble fibers remains unproven. The objective of this study was to examine the associations between soy-soluble polysaccharides and flaxseed gum concentration, product viscosity, and the postprandial glycemic and insulinemic responses in the context of glucose solutions as well as fluid and gelled dairy products. METHODS: Twelve healthy males participated in a randomized crossover postprandial study in which they visited the laboratory following overnight fasts on 11 occasions to consume one of 11 study treatments, each consisting of 50 g available carbohydrates. The study treatments included a glucose reference (in duplicate), glucose solutions containing soy-soluble polysaccharides (6%), flaxseed gum (0.7%), or guar gum (0.23%), all matched for an apparent viscosity of 61 mPa·s at 50 s⁻¹, as well as dairy-based beverages and puddings with 0% or 1% soluble fiber added. Blood samples were collected at fasting and up to 2 hours postprandially for determination of glucose and insulin concentrations. Area under the curve (AUC), peak concentration, and time-to-peak values as well as glycemic index (GI) and insulinemic index (II) were calculated. RESULTS: Fiber fortification of a 50 g glucose solution had no effect on postprandial blood glucose or insulin levels, even at a high concentration (i.e., 6% soy-soluble polysaccharides). Glucose AUC and GI values for the dairy-based beverage (p < 0.05) and pudding (p < 0.01) controls were significantly lower than the glucose reference. Glucose AUC and GI values for the soy-soluble polysaccharide-fortified dairy products (p < 0.01) and flaxseed gum-fortified dairy products (p < 0.001) were significantly lower than the glucose reference. No significant differences were observed between the fiber-fortified fluid and gelled dairy-based study treatments and no significant differences were observed in terms of the insulin AUC, II, and peak insulin concentration between any of the dairy products. CONCLUSIONS: All dairy products had lower glycemic responses relative to the reference, with no effect of beverage versus pudding matrix observed and minimal impact of 1% flaxseed gum or soy-soluble polysaccharides. Product apparent viscosity, but not fiber concentration, was significantly and inversely correlated with glucose AUC and GI.

Caloric beverages consumed freely at meal-time add calories to an ad libitum meal.

The objective was to compare the effects of ad libitum consumption of commonly consumed meal-time beverages on energy and fluid intakes and post-meal average subjective appetite and blood glucose in healthy adults. In a randomized controlled design, 29 males and females consumed to satiation an ad libitum pizza meal with one of five beverages in unlimited amount including water (0 kcal), 1% milk (44 kcal/100 ml), regular cola (44 kcal/100 ml), orange juice (44 kcal/100 ml) and diet cola (0 kcal). Food and fluid intakes were measured at the meal. Average subjective appetite and blood glucose were measured before and for 2h after the meal. Although energy intake from pizza was similar among all beverage treatments, the amount of fluid consumed (g) varied among the beverages with intake of orange juice higher than regular and diet cola, but not different from water or milk. Meal-time ingestion of caloric beverages, milk, orange juice and regular cola, led to higher total meal-time energy intakes compared to either water or diet cola. Post-meal blood glucose area under the curve (AUC) was lower after milk than after meals with water, orange juice and regular cola and post-meal average subjective appetite AUC was lower after milk than after meals with water. Meal intakes of nutrients including protein, calcium, phosphorus, zinc, vitamins B12, A and D were higher at the meal with milk compared to the other beverages. Thus, caloric beverages consumed ad libitum during a meal add to total meal-time energy intake, but 1% milk favors a lower post-meal blood glucose and average subjective appetite score and adds to nutrient intake.

Energy and macronutrient content of familiar beverages interact with pre-meal intervals to determine later food intake, appetite and glycemic response in young adults.

The objective was to compare the effects of pre-meal consumption of familiar beverages on appetite, food intake, and glycemic response in healthy young adults. Two short-term experiments compared the effect of consumption at 30 (experiment 1) or 120 min (experiment 2) before a pizza meal of isovolumetric amounts (500 mL) of water (0 kcal), soy beverage (200 kcal), 2% milk (260 kcal), 1% chocolate milk (340 kcal), orange juice (229 kcal) and cow's milk-based infant formula (368 kcal) on food intake and subjective appetite and blood glucose before and after a meal. Pre-meal ingestion of chocolate milk and infant formula reduced food intake compared to water at 30 min, however, beverage type did not affect food intake at 2h. Pre-meal blood glucose was higher after chocolate milk than other caloric beverages from 0 to 30 min (experiment 1), and after chocolate milk and orange juice from 0 to 120 min (experiment 2). Only milk reduced post-meal blood glucose in both experiments, suggesting that its effects were independent of meal-time energy intake. Combined pre- and post-meal blood glucose was lower after milk compared to chocolate milk and orange juice, but did not differ from other beverages. Thus, beverage calorie content and inter-meal intervals are primary determinants of food intake in the short-term, but macronutrient composition, especially protein content and composition, may play the greater role in glycemic control.

Entrapment of cyanidin-3-O-glucoside in ß-conglycinin: From interaction to bioaccessibility and antioxidant activity under thermal treatment.

The thermal-induced interaction between ß-conglycinin (7S) and cyanidin-3-O-glucoside (C3G) on the bioaccessibility and antioxidant capacity of C3G was investigated. High ratio of 7S to C3G (1:100) led to a more ordered secondary structure of 7S. Thermal treatment promoted the formation of 7S-C3G complexes via hydrophobic and hydrogen bonds but did not induce the formation of 7S-C3G covalent products. Thermal treatment at 65 °C and 121 °C enhanced the binding affinity of 7S-C3G complexes by 46.19 % and 1203 % compared with 25 °C. The 7S-C3G interaction decreased C3G bioaccessibility by 4.37 %, 8.74 %, and 46.37 % at 25 °C, 65 °C, and 121 °C. Diphenylpicrylhydrazyl (DPPH) and ABTS antioxidant capacity assay indicated an antagonistic effect between 7S and C3G. The increased binding affinity of C3G to 7S limited the bioaccessibility of C3G and promoted the antagonism of antioxidant capacity between 7S and C3G. 7S addition was detrimental to the antioxidant capacity and bioaccessibility of C3G in vitro after thermal processing.

The digestive fate of beef versus plant-based burgers from bolus to stool.

Ultra-processed, plant-based burgers (PB) and traditional comminuted-beef burgers (BB) share similar organoleptic characteristics, yet a knowledge gap exists in understanding how consumption of these divergent physical structures alters the lipemic response and gut microbiota. PB, comprised of highly refined ingredients, is formulated with no intact whole food structure, while BB entraps lipids throughout the myofibrillar protein network. PB presented significantly higher free fatty acid (FFA) bioaccessibility (28.2 ± 4.80 %) compared to BB (8.73 ± 0.52 %), as obtained from their FFA release profiles over digestion time after characterizing them with a modified logistic model (SLM), using the simulated TIM Gastro-Intestinal Model (TIM-1). Additionally, the rate of lipolysis, k, obtained from the SLM for PB (90% CI [0.0175, 0.0277] min-1) was higher than for BB (90% CI [0.0113, 0.0171] min-1). Using the Simulated Human Intestinal Microbial Ecosystem (SHIME®), the Firmicutes to Bacteroidetes ratio (F/B ratio) was significantly higher for PB than BB; and linear discriminant analysis effect size (LEfSe) showed Clostridium and Citrobacter were more highly represented in the microbial community for the PB feed, whereas BB feed differentially enriched Megasphaera, Bacteroides, Alistipes, and Blautia at the genus level. Additionally, short-chain fatty acid (SCFA) production was altered (p < 0.05) site-specifically in each colon vessel, which could be attributed to the available substrates and changes in microbial composition. Total SCFAs were significantly higher for PB in the ascending colon (AC) and descending colon (DC) but higher for BB only in the transverse colon (TC). This research illustrates the crucial role of meat analog physical structure in modulating nutritional aspects beyond food composition alone.

A new quantitative method to measure activity of ice structuring proteins using differential scanning calorimetry.

There are very few quantitative assays to measure the activity of antifreeze proteins (AFPs, or Ice Structuring Proteins, ISPs) and these can be prone to various inaccuracies and inconsistencies. Some methods rely only on unassisted visual assessment. When microscopy is used to measure ice crystal size, it is critical that standardized procedures be adopted, especially when image analysis software is used to quantify sizes. Differential Scanning Calorimetry (DSC) has been used to measure the thermal hysteresis activity (TH) of AFPs. In this study, DSC was used isothermally to measure enthalpic changes associated with structural rearrangements as a function of time. Differences in slopes of isothermal heat flow vs. time between winter wheat ISP or AFP type I containing samples, and those without ISP or AFP type I were demonstrated. ISP or AFP type I containing samples had significantly higher slopes compared to those without ISP or AFP type I. Samples with higher concentration of ISP or AFP type I showed higher slope values during the first hour and took up to 3 hr to attain equilibrium. Differences were attributed to activity of the proteins at the ice interface. Proteinaceous activity of ISPs or AFP type I was confirmed by loss of activity after treatment with protease.

Polyphenol-Polysaccharide Complex: Preparation, Characterization, and Potential Utilization in Food and Health.

Polysaccharides and polyphenols coexist in many plant-based food products. Polyphenol-polysaccharide interactions may affect the physicochemical, functional, and physiological properties, such as digestibility, bioavailability, and stability, of plant-based foods. In this review, the interactions (physically or covalently linked) between the selected polysaccharides and polyphenols are summarized. The preparation and structural characterization of the polyphenol-polysaccharide conjugates, their structural-interaction relationships, and the effects of the interactions on functional and physiological properties of the polyphenol and polysaccharide molecules are reviewed. Moreover, potential applications of polyphenol-polysaccharide conjugates are discussed. This review aids in a comprehensive understanding of the synthetic strategy, beneficial bioactivity, and potential application of polyphenol-polysaccharide complexes.

The effects of ß-lactoglobulin on cyanidin-3-O-glucoside antioxidant activity and bioaccessibility after heat treatment.

The impact of heat treatment at different temperatures on the interaction of ß-lactoglobulin (ß-Lg) and anthocyanin-3-O-glucoside (C3G) was studied. Heat treatment and the addition of C3G changed the secondary structure of ß-Lg with decreasing ß-sheets and increasing random coils. Interactions between C3G and ß-Lg were mainly via hydrogen bonds and van der Waals forces at 25 °C. The elevated temperature promoted hydrophobic interactions between C3G and ß-Lg due to an increase in the hydrophobic groups and amino groups on the surface of ß-Lg molecules. The addition of ß-Lg to the C3G eliminated heat-induced thermal degradation of C3G. The ß-Lg-C3G interactions accompanied with increased particle size and constant zeta potential could increase the antioxidant capacity of C3G approximately by 4% to 10% and protect the colour of C3G from degradation under heat treatment. The C3G bioaccessibility with ß-Lg addition increased by 26.08%, 33.45%, 83.09%, 72.27%, and 354.62% compared with C-25, C-60, C-85, C-100, and C-121, respectively. The protective effect of the non-covalent interactions on C3G at high temperatures (85 °C to 121 °C) was significantly stronger than at 25 °C and 60 °C. The application of ß-Lg in foodstuffs could enhance the antioxidant activity and bioaccessibility of C3G.

Conformational Properties of Flaxseed Rhamnogalacturonan-I and Correlation between Primary Structure and Conformation.

The pectic polysaccharides extracted from flaxseed (Linum usitatissiumum L.) mucilage and kernel were characterized as rhamnogalacturonan-I (RG-I). In this study, the conformational characteristics of RG-I fractions from flaxseed mucilage and kernel were investigated, using a Brookhaven multi-angle light scattering instrument (batch mode) and a high-performance size exclusion chromatography (HPSEC) system coupled with Viscotek tetra-detectors (flow mode). The Mw of flaxseed mucilage RG-I (FM-R) was 285 kDa, and the structure-sensitive parameter (ρ) value of FM-R was calculated as 1.3, suggesting that the FM-R molecule had a star-like conformation. The Mw of flaxseed kernel RG-I (FK-R) was 550 kDa, and the structure-sensitive parameter (ρ) values ranged from 0.90 to 1.21, suggesting a sphere to star-like conformation with relatively higher segment density. The correlation between the primary structure and conformation of RG-I was further discussed to better understand the structure-function relationship, which helps the scale-up applications of pectins in food, pharmaceutical, or cosmetic industries.

Fluorescent labeling affected the structural/conformational properties of arabinoxylans.

Three fluorescent-labeling methods, including DMSO/DBTD, reductive amination and fluoresceinamine (FA), were applied to label arabinoxylan (AX). The conjugates were named AF, ATF and ACF, respectively. Compared to AX, the water solubility of AF significantly decreased while that of ATF significantly increased (p < 0.05); both showed decreased solubility with increasing degree of substitution (DS). However, AX was not successfully labeled by the FA method due to poor solubility. The structural and conformational properties of the AF and ATF conjugates under different DS were compared. Results showed that fluorochrome (FITC) was successfully grafted onto AX molecule by using the DMSO/DBTD and reductive amination methods. A slight increased Mw was noticed for both AF and ATF. AF existed in a more compact conformation, while the chain conformation of ATF was more elongated at a lower DS (1.15 %) and more compact at a higher DS (1.34 %).

Catechin-grafted arabinoxylan conjugate: Preparation, structural characterization and property investigation.

In this study, a high molecular weight arabinoxylan (AX, Mw: 694 kDa) from wheat bran was alkaline extracted and covalently linked with Catechin (CA) by free radical catalytic reaction. Comparing to AX, arabinoxylan-catechin (AX-CA) conjugates demonstrated an extra UV-vis absorption peak at 274 nm, a new FT-IR absorption band at 1516 cm-1 and new proton signals at 6.5-7.5 ppm, which all confirmed the covalently linked structure. Grafting CA onto AX not only decreased the molecular weight, thermal stability and apparent viscosity of AX, but also enhanced its inhibition effects on starch digestibility in vitro. The in vitro fermentation test with pig feces showed that the degradation & utilization rate of AX, the total short-chain fatty acid (SCFA) and acetic acid levels produced all were significantly delayed after grafting. This study provided a novel approach to synthesize AX-CA conjugates that could be a novel dietary fiber of enhanced functional/bioactive properties using in the fields of functional foods and medicine.