Relating the composition and air/water interfacial properties of wheat, rye, barley, and oat dough liquor

The influence of water-soluble arabinoxylan on the rheological properties of model dough and the interfacial properties of imitation dough liquor

Imitation dough liquor was formulated from natural dough liquid phase components, primarily comprising water-soluble arabinoxylan and wheat-soluble protein. It was found that arabinoxylan limited the diffusion rate of actively adsorbing components (Kdiff: -0.134 mNm-1 s-0.5 to -0.0573 mNm-1 s-0.5) and decreased the zeta potential (10.91 ± 1.31 mV to 5.76 ± 0.27 mV), which enhanced the composite viscosity and exhibited viscous properties in the low shear rate range. Model dough viscoelasticity decreased while rigidity improved with rising arabinoxylan ratios and critical thresholds existed (1:1.5 wheat, 1:2 potato). Arabinoxylan-enriched dough exhibited elevated tanδ values during thermal processing, enhancing ductility and plasticity compared to controls. The "film-like" shaped structure observed in the dough cavity contributes to maintaining the stability of the air-water interface, which in turn affects the rheological properties of the dough. This research establishes foundations for improving high fiber, low glycemic index fermented products.

Integrative experimental and computational analysis of the impact of KGM's polymerization degree on wheat starch's pasting and retrogradation characteristics

This study investigated the influence of Konjac Glucomannan (KGM) with varying degrees of polymerization (DKGMx) on the gelatinization and retrogradation characteristics of wheat starch, providing new insights into starch-polysaccharide interactions. This research uniquely focuses on the effects of DKGMx, utilizing multidisciplinary approaches including Rapid Visco Analysis (RVA), Differential Scanning Calorimetry (DSC), rheological testing, Low-Field Nuclear Magnetic Resonance (LF-NMR), and molecular simulations to assess the effects of DKGMx on gelatinization temperature, viscosity, structural changes post-retrogradation, and molecular interactions. Our findings revealed that higher degrees of polymerization (DP) of DKGMx significantly enhanced starch's pasting viscosity and stability, whereas lower DP reduced viscosity and interfered with retrogradation. High DP DKGMx promoted retrogradation by modifying moisture distribution. Molecular simulations revealed the interplay between low DP DKGMx and starch molecules. These interactions, characterized by increased hydrogen bonds and tighter binding to more starch chains, inhibited starch molecular rearrangement. Specifically, low DP DKGMx established a dense hydrogen bond network with starch, significantly restricting molecular mobility and rearrangement. This study provides new insights into the role of the DP of DKGMx in modulating wheat starch's properties, offering valuable implications for the functional improvement of starch-based foods and advancing starch science.

Advances in the formation mechanism of set-type plant-based yogurt gel: a review

Plant-based yogurt has several advantages over traditional yogurt, such as being lactose and cholesterol-free, making it more suitable for individuals with cardiovascular and gastrointestinal diseases. The formation mechanism of the gel in plant-based yogurt needs more attention because it is associated with the gel properties of yogurt. Most plant proteins, except for soybean protein, have poor functional abilities, such as solubility and gelling properties, which limits their application in most food items. This often results in undesirable mechanical quality of plant-based products, particularly plant-based yogurt gels, including grainy texture, high syneresis, and poor consistency. In this review, we summarize the common formation mechanism of plant-based yogurt gel. The main ingredients, including protein and non-protein components, as well as their interactions involved in the gel are discussed to understand their effects on gel formation and properties. The main interventions and their effects on gel properties are highlighted, which have been shown to improve the properties of plant-based yogurt gels effectively. Each type of intervention method may exhibit desirable advantages in different processes. This review provides new opportunities and theoretical guidance for efficiently improving the gel properties of plant-based yogurt for future consumption.

Enhancing the technofunctionality of γ-aminobutyric acid enriched germinated wheat by modification of arabinoxylan, gluten proteins and liquid lamella of dough

To enhance the technofunctionality of germinated wheat enriched with γ-aminobutyric acid, xylanase (Xyn) and glucose oxidase (Gox) were incorporated with emphasis on modifying the key components. Combination of Xyn and Gox enhanced steamed bread quality with optimum loaf volume and textural property. Continuous and dense gluten network was facilitated and improved viscoelasticity of dough. Water solubility of arabinoxylan (AX) enhanced with Xyn and the molecular weight was more homogeneous distributed throughout bread making process with Xyn and Gox. Polymerization behavior of α-/γ-gliadin and glutenin was suppressed in steamed bread, while incorporation of AX to insoluble proteins was enhanced by enzymes. In addition, the promoted formation of high molecular weight glycoprotein in the liquid lamella of dough enhanced the thermal stability of foams and contribute to superior quality of steamed bread. Results demonstrated that germinated wheat could be exploited as a functional ingredient with desirable technofunctionality by modification of the components.

Surface tension of native and modified plant seed proteins

The present review, dedicated to Prof. Zbigniew Adamczyk on the occasion of his 70th anniversary, covers the literature data on surface tension and surface compression (dilational) rheology of the adsorbed layers of 21 plant seed proteins (10 leguminous and 11 non-leguminous plants). They are typically analyzed as protein concentrates or isolates, the latter usually obtained by isoelectric precipitation or diafiltration. Despite generally lower solubility, as compared to their animal counterparts (lactoglobulins, caseins, albumins, etc.), the plant seed proteins are also capable of lowering surface tension and forming viscoelastic adsorbed layers. Many seed proteins serve mostly as amino acids reservoirs for the future seedling (storage proteins), hence their instantaneous amphiphilicity is not always sufficient to induce strong adsorption at the aqueous-air interface. They can be, however, conveniently unfolded, hydrolyzed and/or chemically/enzymatically modified to expose more hydrophilic or hydrophobic patches. As shown in numerous contributions reviewed below, the resulting shift of the hydrophilic-lipophilic balance can boost their surface activity to the level comparable to that of many animal proteins or low molecular weight surfactants. An important advantage of the plant seed proteins over the animal ones is their much lower environmental cost and abundance in many plants (e.g. ~40% in sunflower or soybean seeds).

Isolation, Structural, Functional, and Bioactive Properties of Cereal Arabinoxylan─A Critical Review

Arabinoxylans (AXs) are widely distributed in various cereal grains, such as wheat, corn, rye, barley, rice, and oat. The AX molecule contains a linear (1,4)-β-D-xylp backbone substituted by α-L-araf units and occasionally t-xylp and t-glcpA through α-(1,2) and/or α-(1,3) glycosidic linkages. Arabinoxylan shows diversified functional and bioactive properties, influenced by their molecular mass, branching degree, ferulic acid (FA) content, and the substitution position and chain length of the side chains. This Review summarizes the extraction methods for various cereal sources, compares their structural features and functional/bioactive properties, and highlights the established structure-function/bioactivity relationships, intending to explore the potential functions of AXs and their industrial applications.

Baking Quality Assessment of Twenty Whole Grain Oat Cultivar Samples

Whole grain oat has become an increasingly popular baking ingredient. Still, oat baking poses many industrial challenges because the baking quality criteria have not been set for whole grain oat flours, and cultivar variation remains unknown. We aimed to assess the baking quality variation of twenty whole grain oat cultivar samples, and to identify the factors that caused the variation. It was hypothesised that by optimising the water absorption of the dough (i.e., dough yield) by test baking method, the best baking potential could be achieved for all oat cultivar samples. The baking trials were conducted as whole oat baking, without wheat or gluten additions. In most of the samples, good baking quality was obtained by dough yield optimisation. The highest specific volumes (1.9–1.93 mL/g) and best crumb properties were achieved in the samples with the highest optimal dough yields, 205. However, baking quality varied, as all samples could not be baked with good quality at high dough yields. Additionally, small median particle size and high fat content of the oat flours were related to good baking properties of whole grain oat at optimised dough yield (p < 0.05). These findings can benefit the development and the optimisation of industrial oat baking processes.

Effect of Bran Pre-Treatment with Endoxylanase on the Characteristics of Intermediate Wheatgrass (Thinopyrum intermedium) Bread

Previous work indicated that bran removal promotes network formation in breads prepared from intermediate wheatgrass (IWG) flour. However, refinement reduces yields as well as contents of nutritionally beneficial compounds such as fiber. This study evaluated xylanase pretreatment of IWG bran as a processing option to enhance the properties of bread made with half of the original bran content. Xylanase pretreatment did not affect stickiness but significantly reduced hardness and increased specific loaf volumes compared to negative (without xylanase) and positive controls (with xylanase but without pretreatment). However, the surface of breads with pretreated bran was uneven due to structural collapse during baking. Fewer but larger gas cells were present due to pretreatment. Addition of ascorbic acid modulated these effects, but did not prevent uneven surfaces. Accessible thiol concentrations were slightly but significantly increased by xylanase pretreatment, possibly due to a less compact crumb structure. Endogenous xylanases (apparent activity 0.46 and 5.81 XU/g in flour and bran, respectively) may have been activated during the pretreatment. Moreover, Triticum aestivum xylanase inhibitor activity was also detected (193 and 410 InU/g in flour and bran). Overall, xylanase pretreatment facilitates incorporation of IWG bran into breads, but more research is needed to improve bread appearance.

Gas cell stabilization by aqueous-phase constituents during bread production from wheat and rye dough and oat batter: Dough or batter liquor as model system

Proper gas cell stability during fermentation and baking is essential to obtain high-quality bread. Gas cells in wheat dough are stabilized by the gluten network formed during kneading and, from the moment this network locally ruptures, by liquid films containing nonstarch polysaccharides (NSPs) and surface-active proteins and lipids. Dough liquor (DL), the supernatant after ultracentrifugation of dough, is a model system for these liquid films and has been extensively studied mostly in the context of wheat bread making. Nonwheat breads are often of lower quality (loaf volume and crumb structure) than wheat breads because their doughs/batters lack a viscoelastic wheat gluten network. Therefore, gas cell stabilization by liquid film constituents may be more important in nonwheat than in wheat bread making. This manuscript aims to review the knowledge on DL/batter liquor (BL) and its relevance for studying gas cell stabilization in wheat and nonwheat (rye and oat) bread making. To this end, the unit operations in wheat, rye, and oat bread making are described with emphasis on gas incorporation and gas cell (de)stabilization. A discussion of the knowledge on the recoveries and chemical structures of proteins, lipids, and NSPs in DLs/BLs is provided and key findings of studies dealing with foaming and air-water interfacial properties of DL/BL are discussed. Next, the extent to which DL/BL functionality can be related to bread properties is addressed. Finally, the extent to which DL/BL is a representative model system for the aqueous phase of dough/batter is discussed and related to knowledge gaps and further research opportunities.

Lupin Protein Isolate Structure Diversity in Frozen-Cast Foams: Effects of Transglutaminases and Edible Fats

This study addresses an innovative approach to generate aerated foods with appealing texture through the utilization of lupin protein isolate (LPI) in combination with edible fats. We show the impact of transglutaminases (TGs; SB6 and commercial), glycerol (Gly), soy lecithin (Lec) and linoleic acid (LA) on the micro- and nanostructure of health promoting solid foods created from LPI and fats blends. 3-D tomographic images of LPI with TG revealed that SB6 contributed to an exceptional bubble spatial organization. The inclusion of Gly and Lec decreased protein polymerization and also induced the formation of a porous layered material. LA promoted protein polymerization and formation of homogeneous thick layers in the LPI matrix. Thus, the LPI is a promising protein resource which when in blend with additives is able to create diverse food structures. Much focus has been placed on the great foamability of LPI and here we show the resulting microstructure of LPI foams, and how these were improved with addition of TGs. New food applications for LPI can arise with the addition of food grade dispersant Lec and essential fatty-acid LA, by improved puffiness, and their contributing as replacer of chemical leavening additives in gluten-free products.

Normal-Phase HPLC-ELSD to Compare Lipid Profiles of Different Wheat Flours

Normal-phase high-performance liquid chromatography (HPLC) is widely used in combination with evaporative light scattering detection (ELSD) for separating and detecting lipids in various food samples. ELSD responses of different lipids were evaluated to elucidate the possibilities and challenges associated with quantification by means of HPLC-ELSD. Not only the number and type of polar functional groups but also the chain length and degree of unsaturation of (free or esterified) fatty acids (FAs) had a significant effect on ELSD responses. Tripalmitin and trilinolein yielded notably different ELSD responses, even if their constituting free FAs produced identical responses. How FA structure impacts ELSD responses of free FAs is thus not predictive for those of triacylglycerols and presumably other lipids containing esterified FAs. Because ELSD responses of lipids depend on the identity of the (esterified) FA(s) which they contain, fully accurate lipid quantification with HPLC-ELSD is challenging and time-consuming. Nonetheless, HPLC-ELSD is a good and fast technique to semi-quantitatively compare the levels of different lipid classes between samples of comparable FA composition. In this way, lipid profiles of different flours from near-isogenic wheat lines could be compared.

Genetic variation in wheat grain quality is associated with differences in the galactolipid content of flour and the gas bubble properties of dough liquor

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A QTL for breadmaking quality is associated with more galactolipids in flours.

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Dough liquor fractions from the same flours also have higher galactolipid contents.

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The dough liquor fractions with higher galactolipids exhibit increased elasticity.

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These increases indicate a mechanism of action for the quality QTL.

Lipids affect the quality of wheat flour for breadmaking. One possible mechanism is stabilization of the gas cells which are formed during dough mixing and expanded during fermentation, leading to a greater loaf volume and evenness of texture. We therefore compared the lipidomic profiles of flour and dough liquor fractions (which contain surface-active components present at the gas bubble interface) from two sets of wheat lines differing in allelic variation at a QTL for loaf volume. Analyses of fractions from three field trials showed consistent increases in the contents of galactolipids (monogalactosyl diglyceride and digalactosyl diglyceride) in flour and dough liquor of the lines with the increasing (good quality) allele. Biophysical analysis showed that this was associated with greater elasticity of the dough liquor fraction. This is consistent with published studies reporting a relationship between galactolipids and breadmaking quality and suggests a mechanism of action for the QTL.

Dietary fibre from berry-processing waste and its impact on bread structure: a review

The structure and function of by-products of berry-processing industries are reviewed, with particular attention to dietary fibre (DF) and its effects in food products. The complex chemical composition and physicochemical characteristics of DF have been investigated and strategies for extraction of specific fractions that provide tailored technological and physiological functionality have been reviewed. The aim of this review is to describe in detail the structural composition and isolation methods of dietary fibre derived from berry by-products, and to explore their potential functionality in foods. The goal is to introduce DF from berry waste streams into the food chain, for which bread is a major vehicle. However, the appeal of bread lies in its aerated structure, for which DF is generally detrimental. The technological influence of DF on the formation and stabilization of the aerated structure of bread is therefore reviewed, in order to understand how to incorporate DF into bread while maintaining palatability. The aerated structure of bread is stabilized by two mechanisms: the gluten matrix and the liquid film surrounding bubbles. Incorporating DF successfully into bread requires understanding its interactions with both of these mechanisms. DF fractions from berries offer superior nutritional value compared to cereal fibre, potentially with less damage to bread structure, due to the higher proportion of soluble fibre. By-products from berry-processing industries could be used as a source of technologically and nutritionally distinctive DF to fabricate foods with enhanced nutritional value. © 2019 Society of Chemical Industry.