Insoluble dietary fibre (IDF) accounts for more than 90% of the total dietary fibre in okara and has the potential as a functional ingredient. However, IDF in raw okara has some disadvantages when ...used in food industries so its modification is needed. This paper focused on IDF in okara modified by fermentation by Kluyveromyces marxianus. Two kinds of modified IDFs, namely, MIDF1 and MIDF2, were obtained through simple fermentation and the combination of fermentation and β-glucosidase hydrolysis at home. The purity of IDF ranged from 75.83 (OIDF) to 81.0 (MIDF1) and 87.70 g/100 g (MIDF2). Colour analysis, scanning electron micrographs, bulk density and viscosity showed positive effects for modification. The functional properties of SC, WHC, OHC, GAC and CAC in MIDF were all increased in modified IDF, but MIDF2 showed a more favourable effect than MIDF1. Overall, the research demonstrated that K. marxianus fermentation can improve the structure and function of IDF from okara, which provides guidance for the development and utilization of okara in the food industry.
•IDF from okara was modified by K. marxianus fermentation.•Modified IDF has a favourable effect on the structure.•Modified IDF increased functional properties.•Combining β-glucosidase hydrolysis was a more efficient way to modify IDF.
•CIDF-400 had the strongest adsorption and activity inhibition capacity for PL.•CIDF could quench PL by dynamic quenching process induced by the electrostatic interactions.•Binding of CIDF to PL ...induced structural and conformational change in PL.•Potential suppression mechanism was elucidated by multiple spectroscopy.
Insoluble dietary fibre from citrus peels (CIDF) was found to have adsorption and inhibitory effect on the activity of pancreatic lipase (PL). CIDF-400 exhibited the greatest adsorption and activity inhibition effect on PL. The fluorescence quenching spectra indicated that CIDF could quench PL through a dynamic quenching process induced by the electrostatic interactions with only one binding site between them. The synchronous fluorescence and three-dimensional fluorescence spectra showed that CIDF might combine with PL to induce the increase in hydrophobicity and the reduction in polarity of tyrosine (Tyr) and tryptophan (Try) residues, which further led to the conformational alternations of PL. Moreover, circular dichroism (CD) showed that CIDF altered the secondary structure of PL, decreased α-helical structure content, and increased β-sheet structure content, potentially resulting in PL structure opening and its active site exposure. This study provides new perspectives for the application of CIDFs produced from agricultural waste in regulating lipid metabolism.
This study aimed to identify the dietary fibre profiles of various winged bean components (green pods, whole seeds, endosperms, seed coats, and canned whole seeds). Soluble dietary fibre (SDF), ...insoluble dietary fibre (IDF) (hemicellulose, cellulose, and lignin), total dietary fibre (TDF), and oligosaccharide components (raffinose, stachyose, and verbascose), were analyzed. The various winged bean components had a higher IDF content than SDF content (21.12–50.11% and 0.83–1.25%, respectively), with the highest TDF content observed in the seed coat (51.81%). Raffinose was the most dominant oligosaccharide component in green pods (2.7 mg/g), while verbascose was the most dominant component in all seed form samples, including seed coats (1.41–3.65 mg/g). The IDF in all samples was dominated by cellulose (5.07–39.34%), followed by hemicellulose (1.5–27.19%), and lignin (0.09–0.98%). Seed dehusking led to significant decreases in all types of dietary fibre analyzed, except for stachyose. Soaking and sterilization processes resulted in an increase in SDF, but decreased IDF, stachyose, verbascose, and hemicellulose compared to raw whole seeds. Principal component analysis (PCA) revealed that raw whole seeds still exhibit similarities in dietary fibre composition with canned seeds, but differ from green pods, endosperms, and seed coats. These findings imply that all edible parts of winged beans offer a large quantity of dietary fibre, especially whole seeds, which have potential benefits as prebiotic sources to improve health.
•Whole seeds have higher levels of SDF, IDF, and TDF compared to green pods.•Green pods were dominated by raffinose, while seeds were dominated by verbascose.•All samples were mainly composed of cellulose, followed by hemicellulose and lignin.•Dehusking, soaking, and sterilization alter the composition of dietary fiber.•All edible parts of winged beans potentially serve as prebiotic sources.
Dietary fibre and polyphenols are widely used as functional food ingredients. In this study, carbohydrate composition and bound phenolics in dietary fibre of mango peels were determined. Total ...dietary fibre content was in the range of 40.6–72.5%. Galactose, glucose and arabinose were the major neutral sugars in insoluble and soluble dietary fibres. Bound polyphenolic and flavonoid contents were in the range of 8.1–29.5 and 0.101–0.392 mg/g, respectively, and were found to be more in ripe peel than in raw peel. Gallic, protocatechuic and syringic acids were the bound phenolic acids, and kaempferol and quercetin were the major flavonoids of the peels. Ferulic acid was identified only in dietary fibre of Raspuri peels. Thus, the studies indicated the presence of significant amount of bound phenolics in dietary fibre, which adds additional health benefits of antioxidant properties of mango peel, which can be used in functional foods.
•Dietary fibre scavenges carbonyl compounds under simulated physiological conditions.•Bound polyphenols contribute to the carbonyl trapping capacity of dietary fibre.•Carbonyl trapping capacity of ...dietary fibre is retained after in vitro digestion.•Methylglyoxal adducts of bound gallic acid, catechin and quercetin are identified.
Polyphenols bound to insoluble fibre may scavenge reactive carbonyl species by surface chemical reactions. In the present study, this hypothesis was tested by investigating the ability of bound-polyphenol rich insoluble dietary fibre (BP-IDF) isolated from blackberry pomace, red cabbage, and wheat bran in scavenging carbonyl compounds. Three BP-IDF showed high scavenging efficacy for glyoxal, methylglyoxal, acrolein and malondialdehyde. Upon in vitro digestion, trapping capacity was retained by the insoluble fraction suggesting that carbonyl trapping activity and physiological relevance needs to be extended to undigestible materials. The removal of bound polyphenols from the polysaccharide backbones through alkaline and acidic treatment reduced by up to 90% of trapping capacity of BP-IDF. Moreover, methylglyoxal-polyphenol adducts were detected bound to blackberry pomace BP-IDF after hydrolysis. These findings demonstrated that polyphenols bound to IDF scavenged reactive carbonyl species and highlighted the physiological relevance of BP-IDF in limiting carbonyl stress along all the gastrointestinal tract.
The effects of in vitro gastric digestion conditions on the properties of the soluble (SC) and insoluble (IC) components of apple cell walls were investigated. Apple fruits were homogenized and ...successively treated in natural saliva (3 min, 37 °C) and in simulated gastric fluid (SGF, 2 h, 37 °C). The incubation pH (5.0, 3.0, 1.8) and the ratio of apple mixture to SGF (1:0.05, 1:0.5, 1:1, v/v) were varied. Pectin (GalA 74 wt%, Mw 1800 × 103 g/mol, yield 1.9–2.4%) was a major high-molecular-weight component of SC obtained at pH 1.8, whereas at pH 3.0 and 5.0, proteins (41–55 wt%) and phenolic compounds (2.7–3.1 wt%) were dissolved together with pectins (15–24 wt% GalA, Mw 28-33 × 103 g/mol, yield 0.6–0.8%). Rhamnogalacturonan-I (RG-I) and homogalacturonan (HG) were identified in all pectins. HG was the major component of pectins extracted at pH 1.8; RG-I was the major component of pectins extracted at pH 3.0 and 5.0. The dissolution of cell wall pectins of apple fruits in SGF increased the viscosity of the SC of the apple mixture, decreased the hardness of the apple mixture, increased the water retention and water swelling capacity of the IC, and improved the capacity of high-molecular-weight soluble and insoluble components to retard glucose diffusion. The difference in surface morphology of insoluble components obtained at different values of pH incubation was observed under a SEM.
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•The pH affects solubility of apple cell wall pectins during incubation in SGF.•HG was the major component of pectins extracted at pH 1.8•RG-I was the major component of pectins extracted at pH 3.0 and 5.0•Incubation at pH 1.8 enhances the hydration properties of insoluble components.•Pectin and insoluble components isolated at pH 1.8 similarly inhibit glucose diffusion.
Dietary fibre fortified products have increased in popularity as health-conscious consumers seek convenient ways to increase fibre intake. Fibres from wholegrains are particularly desirable ...inclusions in food products because of their proven physiological health-benefits. When fortifying beverages with fibre, however, the insoluble dietary fibre components present in wholegrains often contribute to unpleasant gritty sensations making the products unpalatable. Consequently, designing wholegrain-fortified beverages with sufficient fibre-content to make health related fibre claims is a major challenge in the food manufacturing industry. This work aims to take a systematic approach in identifying the texture/mouthfeel related sensory impact and interaction between two commercial oat fibre ingredients (Oatwell28XF® and Milled Oats) when added to a model beverage system. Eighteen samples were prepared containing either or both the ingredients, at varying levels, and were assessed by a trained panel using conventional sensory descriptive techniques. The results indicate that the two different oat bran fibres produced distinct mouthfeel perceptions which could be attributed to the varying soluble and insoluble fibre content of the samples. Insoluble dietary fibre concentrations above 2% (w/w) resulted in particle-related sensory properties chalkiness, dryness and particle perception, which dominated the overall mouthfeel and textural sensory perception of the samples. Samples with predominantly soluble β-glucan, resulted in perceptions of smoothness, sliminess and stickiness residue, while thickness, mouthcoating and cloying sensations were driven by total fibre concentration, irrespective of fibre solubility. This work provides a solid foundation for food manufacturers aiming to rationally design and develop nutritionally superior fibre-fortified beverages and is relevant to fibre content concentrations required for labelling/nutrition claims for consumer products in many developed nations.
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•A systematic approach allowed for a rational investigation of the sensory interaction between soluble and insoluble fibres in a model beverage matrix.•Samples with added Oatwell28XF®, predominantly soluble β-glucan, resulted in perceptions of smoothness, sliminess and stickiness residue.•Samples with added Milled Oats bran, predominantly comprising insoluble cellulosic fibres, resulted in particle perception, chalkiness and dryness.•Sensory attributes thickness, mouthcoating and cloying were driven by total fibre concentration, irrespective of fibre solubility.•The sensory threshold for insoluble fibre particle perception was just below 2% (w/w) insoluble dietary fibre in the model beverage matrix.
The winemaking grape pomaces are rich in bioactive phytochemicals and dietary fibre (DF). DFs are phenolic-rich DF matrix and are dietary supplement with benefits on human health. As a result of the ...increased attention to sustainability of winemaking by-products, efforts have been made to use grape pomace in different bio-industries. In this review, we summarize the existing knowledge on the bioactivity and potential applications of DF from grape pomace, as well as the chemical compositions of DF. Furthermore, the biological activities of DF such as, anti-cancer activity, antibacterial activity, anti-inflammatory activity, antioxidant activity, improving gastrointestinal health activity, anti-apoptotic activity, preventing cardiovascular disease activity, anti-hypercholesterolemic activity, are discussed. Finally, the possible applications and future prospects of grape pomace DF in various fields are also summarised.
Phenolic compounds associated with dietary fibre are present in free, soluble conjugated and insoluble-bound forms. In this study, total soluble, free, esterified, etherified and insoluble-bound ...phenolic fractions were extracted from the insoluble dietary fibre (IDF) and soluble dietary fibre (SDF) of hulless barley. Total phenolic content (TPC), total flavonoid content (TFC) and antioxidant activities of five phenolic fractions of IDF and SDF were evaluated. Major phenolic acids and flavonoids were analyzed by high performance liquid chromatography. The results revealed that the TPC and TFC of five phenolic fractions of IDF were 2.42–7.33 and 3.08–10.00 times, respectively, which were higher than those in SDF. Insoluble-bound phenolic fractions had the highest TPC and TFC among the five phenolic fractions. A significant positive linear correlation between TPC and antioxidant activity was observed in each of the five phenolic fractions from IDF and SDF (P < 0.05). Furthermore, ferulic acid was an abundant phenolic compound in total soluble and insoluble-bound phenolic fractions among IDF and SDF. This study indicates that IDF and SDF are rich in phenolic compounds which can be considered as functional food ingredients or nutraceuticals.
•Hulless barley dietary fibre is rich in polyphenols with antioxidant capacity.•TPC and TFC of five phenolic fractions of IDF were higher than those of SDF.•Insoluble-bound phenolic fractions had the highest contents among five fractions.•Total phenolic content was strongly correlated with antioxidant activity.•DF can be considered as a functional food ingredient and nutraceutical.
Summary
Okara, a natural source of dietary fibre (DF), is recognised as an edible and safe material. In this study, lactic acid bacteria (LAB) and
Kluyveromyces marxianus
were used to ferment okara ...in separately or in combination, and the physicochemical and functional characteristics of obtained insoluble dietary fibre (IDF) excluded from okara were compared. The result showed that compared with non‐fermented okara, the content of IDF from co‐fermented okara by LAB and
K. marxianus
increased by 6.8%, while separate fermentations were 2.4% and 4.0%. Scanning electron microscopy result showed that the structure of co‐fermented okara IDF was looser and porous with the edge disappeared compared to separate and non‐fermented okara. All the fermentation treatment groups effectively reduced the particle size and affected the cellulose and hemicellulose functional groups of IDF. Furthermore, compared with non‐fermented okara, processing performance, and the activities of hypoglycaemic and hypolipidaemic of IDF were greatly improved in fermented okara.
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