The contribution of glutathione to the destabilizing effect of yeast on wheat dough

Effect of magnetic fields on the structure, properties, baking performance of frozen wheat dough at different frozen stage

As an emerging physical technology, magnetic fields have been used to improve the quality of frozen and refrigerated foods. This study compared the effect of applying a static magnetic field (2 mT) at different stages of freezing and storage on the quality of frozen dough. Results suggested that the magnetic field significantly impacted frozen dough quality. It not only prevented the formation of ice crystals during the pre-freezing stage but also inhibited ice crystal growth during the following frozen storage. This effect helped to maintain the integrity of gluten proteins and their adhesion to starch granules by preventing the breakage of disulfide bonds and the depolymerization of gluten macromolecules. It was also observed that yeast inactivation and glutathione release were reduced, resulting in improved air retention and air production capacity of the dough. This, in turn, led to a more appealing volume and texture quality of the finished bread.

Selenium-enriched yeast, a selenium supplement, improves the rheological properties and processability of dough: From the view of yeast metabolism and gluten alteration

This study investigated the effect mechanism of selenium (Se)-enriched yeast on the rheological properties of dough from the perspective of yeast metabolism and gluten alteration. As the yeast Se content increased, the gas production rate of Se-enriched yeast slowed down, and dough viscoelasticity decreased. The maximum creep of Se-enriched dough increased by 29%, while the final creep increased by 54%, resulting in a softer dough. Non-targeted metabolomics analyses showed that Se inhibited yeast energy metabolism and promoted the synthesis of stress-resistance related components. Glutathione, glycerol, and linoleic acid contributed to the rheological property changes of the dough. The fractions and molecular weight distribution of protein demonstrated that the increase in yeast Se content resulted in the depolymerization of gluten. The intermolecular interactions, fluorescence spectrum and disulfide bond analysis showed that the disruption of intermolecular disulfide bond induced by Se-enriched yeast metabolites played an important role in the depolymerization of gluten.

Solid-state fermentation by S. cerevisiae with high resistance to ferulic acid improves the physicochemical properties of wheat bran and quality of bran-rich Chinese steamed bread

Wheat bran has numerous health benefits, but its poor processing and sensory properties limit its application in the staple food industry. Fermentation by S. cerevisiae changes the performance of wheat bran. However, high levels of ferulic acid (FA) inhibit S. cerevisiae. The effects of solid-state fermentation of S. cerevisiae with high resistance to FA on the physicochemical properties of wheat bran and the quality of bran-rich Chinese steamed bread (CSB) were investigated. The results showed that the growth of S. cerevisiae was inhibited by FA in a dose-dependent manner. Short-term adaptation strategies efficiently improved the tolerance of S. cerevisiae to FA stress. Compared with the parental strain (PS), fermentation of the short-term adapted strains (adapted strains) significantly increased the FA, total phenol, and soluble dietary fiber content in wheat bran. Wheat bran fermented by the adapted strains had a higher antioxidant capacity than wheat bran fermented by PS. In addition, compared with the PS, the wheat bran fermented by the adapted strains can decrease the hardness, improve the specific volume, and the quality of CSB. Thus, solid-state fermentation of the adapted strain is a potentially effective method to improve the nutritional and physicochemical properties of wheat bran as a cereal food ingredient.

Effect of yeast on functional and rheological characteristics of whole wheat flour and its effect on quality of chapati

Chapati is unleavened flat bread originated from Indian sub-continent and is considered as staple product in everyday meals. Its quality attributes are dependent on number of factors including the wheat used, ingredients added and processing parameters. The study was aimed to observe the effect of yeast addition on functional, rheological, and sensory characteristics on whole wheat flour and chapati at varying percentage (0.25-1.0). All the experiments conducted were compared with a control flour/chapati without yeast addition. The results showed that all the attributes were favourably affected with yeast addition when compared with control samples. It was noticed that the peak viscosity, setback, breakdown and final viscosity decreased with yeast addition and the paste obtained had higher gel strength. Alveogragh results also depict the increase in tensile strength and decrease in extensibility of dough on yeast incorporation. Textural and sensory studies revealed that yeast concentration upto 0.75% w/w in whole wheat flour resulted in chapati with good overall acceptability.

Glutathione for Food and Health Applications with Emphasis on Extraction, Identification, and Quantification Methods: A Review

Glutathione is a naturally occurring compound that plays a crucial role in the cellular response to oxidative stress through its ability to quench free radicals, thus mitigating the risk of potential damage, including cell death. While glutathione is endogenously present in different plants and animal cells, their concentration varies considerably. The alteration in glutathione homeostasis can be used as a potential marker for human diseases. In the case of the depletion of endogenous glutathione, exogenous sources can be used to replenish the pool. To this end, both natural and synthetic glutathione can be used. However, the health benefit of glutathione from natural sources derived from fruits and vegetables is still debated. There is increasingly growing evidence of the potential health benefits of glutathione in different diseases; however, the determination and in situ quantification of endogenously produced glutathione remains a major challenge. For this reason, it has been difficult to understand the bioprocessing of exogenously delivered glutathione in vivo. The development of an in situ technique will also aid in the routine monitoring of glutathione as a biomarker for different oxidative stress-mediated diseases. Furthermore, an understanding of the in vivo bioprocessing of exogenously delivered glutathione will also aid the food industry both towards improving the longevity and profile of food products and the development of glutathione delivery products for long-term societal health benefits. In this review, we surveyed the natural plant-derived sources of glutathione, the identification and quantification of extracted glutathione from these sources, and the role of glutathione in the food industry and its effect on human health.

Multi-scale dough adhesion analysis: Relation between laboratory scale, pilot scale and human sensory

Undesired dough adhesion is still a challenge during the production of baked goods. There are various methods for determining the adhesive texture properties of dough. In the majority of scientific papers, dough stickiness is measured analytically by the force-distance recording of dough detachment. In this study, we describe a new multi-scale approach to compare dough adhesion phenomena in a laboratory, pilot sale and human sensory assessment. In it, the adhesive material properties of dough were investigated using a pilot scale toppling device representing dough adhesion behavior in the production process, in the laboratory by texture analysis with the Chen-Hoseney method and furthermore with a new, implemented non-oral human sensory analysis. To simulate different dough adhesion behavior, the dough mechanical and adhesion properties were varied by applying dough-modifying enzymes and different dough storage times. The structural changes in the different wheat dough system were compared by rheological characterization. By characterizing the different adhesion phenomena of the doughs, the sample with bacterial xylanase showed the highest values after 80 min of storage time in all three methods. Correlation analysis revealed a strong relationship between the detachment time (pilot scale) and human sensory assessment attributes (Force R = 0.81, Time R = 0.87, Distance R = 0.92, Stickiness R = 0.80) after 80 min of storage time. Even though human sensory assessment showed limits in the detectability of differences in dough adhesion behavior compared to the Chen-Hoseney method, it was better suited to predict machinability.

Impact of Different Frozen Dough Technology on the Quality and Gluten Structure of Steamed Buns

To advance the industrialization production of steamed buns, the current study explored the freeze-stability of unfermented, pre-fermented and par-steamed frozen dough. The results showed that the steamed bun made from unfermented dough with 2.0% yeast, the pre-fermented dough with a pre-fermented time of 30 min and the par-steamed dough with a pre-steamed time of 15 min showed the best sensory properties quality upon frozen storage. The gassing power of un- and pre-fermented dough gradually decreased, and dough with longer pre-fermented time exhibited more evident loss of gassing power. Freeze-induced depolymerization of gluten protein was the least distinct in the par-steamed dough, followed by the pre- and un-fermented dough, which was probably related to the superior freeze stability of glutenin-gliadin macro-crosslinks upon the pre-steaming stage. The surface hydrophobicity of gluten proteins of frozen dough decreased during the initial storage and was enhanced subsequently, which was related with the combined effects of the unfolding and synchronous aggregation induced by freezing and steaming, respectively. Moreover, the surface hydrophobicity of gluten in par-steamed frozen dough and steamed buns was more resistant to frozen storage, which was probably attributed to the established stable structure during the pre-steaming process.

Modification of myofibrillar protein gelation under oxidative stress using combined inulin and glutathione

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Inulin and glutathione (GSH) are combined to treat myofibrillar proteins (MP).

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GSH significantly suppresses oxidation-induced carbonylation and protein insolubility.

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Inulin, GSH and their combination improve the gelling properties of oxidized MP.

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Treatment with inulin + GSH shows the best oxidative stability and textural characteristics.

The effects of inulin (1.5%), glutathione (GSH, 0.05%), and their combination (1.5% inulin + 0.05% GSH) on the conformational structure and gel performance of pork myofibrillar protein (MP) under oxidation condition were examined. The addition of GSH significantly prevented oxidation-induced carbonylation, reduction of α-helix content, and protein aggregation. As a result, treatment with GSH significantly reduced the particle size of oxidized MP by 35%, increased the solubility by 17.3%, and improved the gelling properties. The presence of inulin also obviously enhanced the gelling behavior of MP under oxidation condition, although it could hardly inhibit the modification of MP structure caused by oxidation. Treatment with inulin + GSH exhibited the highest cooking yield (84.2%) and the best textural characteristics, with a denser and more uniform network structure comprising evenly distributed small pores. The findings of this study provide a useful method for processing meat protein gel products with better oxidative stability and textural properties.

Assessment of the influence of gluten quality on highland barley dough sheet quality by different instruments

This study was to compare the results of texture analyzer with those of farinograph and extensograph and determine whether texture analyzer could be used to evaluate the processing quality of highland barley flour (HBF) dough sheet. The farinograph and extensograph tests were used to determine the reconstituted flour properties, a texture analyzer was applied to measure the tensile strength of HBF dough sheet, and the content of glutenin macropolymer (GMP), free sulfhydryl (-SH) and secondary structure of protein and microstructure in HBF dough sheet were investigated. Furthermore, correlations between these parameters were determined by regression analysis and Pearson correlation coefficient. It was suggested that the reconstituted flours with a higher gluten index showed a higher farinograph quality number (FQN) and greater maximum resistance to extension (R_m ). HBF dough sheets with higher gluten index possessed higher GMP and lower free -SH contents, a more ordered secondary structure of protein, resulting in a more compact gluten network and a stronger tensile strength (TS). The regression and correlation analysis showed that TS was positively correlated with FQN and R_m . In addition, it was significantly correlated with the content of GMP, -SH, secondary structure of protein and gluten network. It was concluded that texture analyzer could be an alternative approach to evaluate the processing quality of HBF dough sheet. Moreover, the gluten index of flours could be used to predict the processing quality of HBF dough sheet. This article is protected by copyright. All rights reserved.

Effects of different solid-state fermentation ratios of S. cerevisiae and L. plantarum on physico-chemical properties of wheat bran and the quality of whole wheat bread

BACKGROUND

The addition of wheat bran (WB) could improve the nutritional quality of whole wheat bread (WWB); however, it also caused many negative effects on the quality of bread. To improve the physico-chemical properties of WB and the quality of WWB, WB was solid-state fermented with different ratios of commercially available S. cerevisiae and L. plantarum, and utilized to prepare WWB.

RESULTS

The physico-chemical properties of WB including dietary fiber content and its components, amino acid composition, and antioxidant activities were determined. After solid-state fermentation, the physico-chemical properties of WB were improved. WB_{Sac:Lac = 2:1} showed higher antioxidant activity (only the total antioxidant activity was slightly lower than WB_{Sac:Lac = 1:1} ), and greater concentration of soluble dietary fiber (9.22%) and essential amino acids / total amino acids (42.04) than the other WB samples. Whole wheat bread quality was investigated by measuring specific volume, porosity, texture, aroma, and volatile compounds. The WWB made with WB_{Sac:Lac = 2:1} showed a higher specific volume, more uniform porosity structure, better texture, and more volatile compounds than the other samples.

CONCLUSION

Using a ratio of yeast and lactobacilli of 2:1, the solid-state fermentation maximally improves the processing properties of WB, and prepares WWB with the best quality. © 2021 Society of Chemical Industry.

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.

A review on mechanistic aspects of individual versus combined uses of enzymes as clean label-friendly dough conditioners in breads

Numerous dough improvers are used alone or in combination to enhance the quality of baked goods such as breads. While modern consumers demand consistent quality, the expectations for ingredients have changed over the past few years, and reformulations have taken place to provide "clean label" options. However, the effects and mechanisms of blended dough conditioners suitable for such baked products have not been systematically summarized. In this review, dough and bread properties as affected by different improver combinations are examined, with a focus on additive or synergistic interactions between enzymes or between enzymes and ascorbic acid. The combination of enzymes that hydrolyze starch and cell wall polysaccharides has been shown to reduce textural hardness in fresh and stored bakes goods such as breads. Enzymes that hydrolyze arabinoxylans, the main nonstarch polysaccharide in wheat, have synergistic effects with enzymes that result in cross-linking of wheat flour biopolymers. In some studies, the effects of bread improvers varied for wheat flours of different strength. Overall, bread products in which wheat is used in whole grain form or in a blend with other flours especially benefit from multiple improvers that target different flour constituents in doughs.

Histamine Intolerance Originates in the Gut

Histamine intolerance (HIT) is assumed to be due to a deficiency of the gastrointestinal (GI) enzyme diamine oxidase (DAO) and, therefore, the food component histamine not being degraded and/or absorbed properly within the GI tract. Involvement of the GI mucosa in various disorders and diseases, several with unknown origin, and the effects of some medications seem to reduce gastrointestinal DAO activity. HIT causes variable, functional, nonspecific, non-allergic GI and extra-intestinal complaints. Usually, evaluation for HIT is not included in differential diagnoses of patients with unexplained, functional GI complaints or in the here-listed disorders and diseases. The clinical diagnosis of HIT is challenging, and the thorough anamnesis of all HIT-linked complaints, using a standardized questionnaire, is the mainstay of HIT diagnosis. So far, DAO values in serum have not been established to correlate with DAO activity in the gut, but the diagnosis of HIT may be supported with determination of a low serum DAO value. A targeted dietary intervention, consisting of a histamine-reduced diet and/or supplementation with oral DAO capsules, is helpful to reduce HIT-related symptoms. This manuscript will present why histamine should also be taken into account in the differential diagnoses of patients with various diseases and disorders of unknown origin, but with association to functional gastrointestinal complaints. In this review, we discuss currently increasing evidence that HIT is primarily a gastrointestinal disorder and that it originates in the gut.

Brewer’s Spent Yeast (BSY), an Underutilized Brewing By-Product

The repurposing of by-products and the reduction of waste from food processing streams is an ever-increasing area of interest. Brewer’s spent yeast (BSY) is a prevalent by-product of the brewing industry. The spent yeast cells are removed at the end of the bulk fermentation. A small amount of it is used to start the next batch of fermentation; however, the majority of the spent yeast is discarded. This discarded yeast is high in nutrients, in particular proteins, vitamins and minerals, as well as containing functional and biologically active compounds such as polyphenols, antioxidants, β-glucans and mannoproteins. At present, BSY is mainly used in animal feed as a cheap and readily available source of protein. This review explores alternative, value-added applications for brewer’s spent yeast including nutritional ingredients, functional food additives as well as non-food applications. A major challenge in the utilization of BSY in food for human consumption is the high level of RNA. An excess of RNA in the diet can lead to an increase in uric acid in the bloodstream, potentially causing painful health conditions like gout. This issue can be overcome by RNA degradation and removal via additional treatment, namely heat treatment and enzymatic treatment. There is potential for the use of BSY ingredients in various food applications, including meat substitutes, bakery products and savory snacks.

Considering histamine in functional gastrointestinal disorders

In westernized countries, adverse reactions to ingested foods are reported to affect up to 20% of the population. Functional, nonspecific, non-allergic gastrointestinal complaints are mainly due to the intolerance/malabsorption of carbohydrates (lactose and fructose), proteins (gluten), and biogenic amines (histamine). Food intolerance/malabsorption is defined by one or several of the above mentioned food components not being degraded and/or absorbed properly within the gastrointestinal tract. Food intolerance/malabsorption causes variable, functional, nonspecific, non-allergic gastrointestinal and extra-intestinal complaints, and a detailed diagnostic workup for all possible etiologic factors in individual patients is essential. Usually, evaluation for histamine intolerance is not included in differential diagnoses of patients with functional, nonspecific, non-allergic gastrointestinal complaints. A targeted dietary intervention for single or possibly combined intolerance/malabsorption is required. In this article, we review currently discussed differential diagnoses and available tests for intolerance/malabsorption. Accordingly, we aim to outline why including histamine and, histamine intolerance, should be considered in differential diagnoses of patients with functional, nonspecific, non-allergic gastrointestinal complaints.

Definition of network types - Prediction of dough mechanical behaviour under shear by gluten microstructure

This study defines network types of wheat gluten to describe spatial arrangements of gluten networks in relation to dough mechanical behaviour. To achieve a high variety in gluten arrangements, ten specific and unspecific gluten-modifying agents in increasing concentrations were added to wheat dough. Gluten microstructure was visualized by confocal laser scanning microscopy and quantified by protein network analysis. Dough rheological behaviour was determined by both oscillatory and creep-recovery tests. Based on correlation matrices and principal component analysis, six different network types were identified and associated to their rheological characteristics: a cleaved (low viscous), rigid (highly viscous), spread (viscoelastic), strengthened (viscoelastic), particulate and dense (highly viscous) or particulate and loose (low viscous) network. Furthermore, rheological dough properties of specifically gluten-modified samples were predicted with five microstructural gluten attributes (lacunarity, branching rate, end-point rate, protein width, average protein length) and assigned properly by the obtained partial least square model with an accuracy up to 90% (e.g., R2Y = 0.84 for G*, 0.85 for tanδ, 0.90 for Jmax). As a result, rheological properties of wheat doughs were predicted from microstructural investigations. This novel, quantitative definition of the relation between structure and mechanical behaviour can be used for developments of new wheat products with targeted properties.

Effect of Glutathione Dehydrogenase of Lactobacillus sanfranciscensis on Gluten Properties and Bread Volume in Type I Wheat Sourdough Bread

Disulfide exchange reactions in wheat dough impact the polymerization of gluten and the volume of bread. In wheat sourdoughs fermented with Lactobacillus sanfranciscensis, glutathione reductase activity accumulates thiols. This study investigated the role of glutathione reductase and NADH oxidase of L. sanfranciscensis on disulfide exchange reactions, peroxide levels, and gluten polymerization in type I wheat sourdoughs. Fermentation with L. sanfranciscensis DSM20451 Δ gshR lacking glutathione reductase activity reduced the thiol levels in dough when compared to the wild type strain L. sanfranciscensis DSM20451. Fermentation with any strain reduced peroxides in wheat doughs when compared to a chemically acidified control. The impact of baker's yeast on thiol and peroxide levels was greater than the impact of lactobacilli. The depolymerization of gluten proteins was dependent on the free thiol content and dough acidification. Bread produced with the glutathione reductase deficient mutant strain had the highest specific volume compared with all the other groups.

Gluten Polymer Networks-A Microstructural Classification in Complex Systems

A classification of gluten polymer networks would support a better understanding of structure-function relationships of any gluten polymer material and thus, the control of processing properties. However, quantification and interpretation of the gluten network structures is challenging due to their complexity. Thus, the network formation was altered by specific gluten-modifying agents (glutathione, ascorbic acid, potassium bromate, glucose oxidase, transglutaminase, bromelain) in this study in order to clarify if structural alterations can be detected on a microstructural level and to specify different polymer arrangements in general. Microstructure analysis was performed by confocal laser scanning microscopy followed by quantification with protein network analysis. It was shown that alterations in gluten microstructure could be elucidated according to the kind of modification in cross-linking (disulphide, (iso) peptide, dityrosyl). Linear correlations of structural network attributes among each other were found, leading to an assertion in general: the higher the branching rate, the thinner the protein threads and the larger the interconnected protein aggregate. Considering the morphological attribute lacunarity, a quantitative classification of different gluten arrangements was established. These assertions were extended by using unspecific gluten-modifying agents in addition to the specific ones. Ultimately, five network types were proposed based on diverse polymer arrangements.

Non-celiac gluten sensitivity: people without celiac disease avoiding gluten-is it due to histamine intolerance?

INTRODUCTION

Food intolerance/malabsorption is caused by food ingredients, carbohydrates (mainly lactose and fructose), proteins (gluten), and biogenic amines (histamine) which cause nonspecific gastrointestinal and extra-intestinal symptoms. Here we focus on possible etiologic factors of intolerance/malabsorption especially in people with non-celiac gluten sensitivity (NCGS) or the so-called people without celiac disease avoiding gluten (PWCDAG) and histamine intolerance.

METHODS

Recognizing the recently described symptoms of NCGS (PWCDAG) we review correlations and parallels to histamine intolerance (HIT).

RESULTS

We show that intestinal and extra-intestinal NCGS (PWCDAG) symptoms are very similar to those which can be found in histamine intolerance.

CONCLUSIONS

After a detailed diagnostic workup for all possible etiologic factors in every patient, a targeted dietary intervention for single or possibly combined intolerance/malabsorption might be more effective than a short-term diet low in fermentable oligo-, di- and monosaccharides and polyols (FODMAP) or the untargeted uncritical use of gluten-free diets.

Substrate-Limited Saccharomyces cerevisiae Yeast Strains Allow Control of Fermentation during Bread Making

Identification and use of yeast strains that are unable to consume one or more otherwise fermentable substrate types could allow a more controlled fermentation process with more flexibility regarding fermentation times. In this study, Saccharomyces cerevisiae strains with different capacities to consume substrates present in wheat were selected to investigate the impact of substrate limitation on dough fermentation and final bread volume. Results show that fermentation of dough with maltose-negative strains relies on the presence of fructan and sucrose as fermentable substrates and can be used for regular bread making. Levels of fructan and sucrose, endogenously present or added, hence determine the extent of fermentation and timing at the proofing stage. Whole meal is inherently more suitable for substrate-limited fermentation than white flour due to the presence of higher native levels of these substrates. Bread making protocols with long fermentation times are accommodated by addition of substrates such as sucrose.

Impact of gas formation kinetics on dough development and bread quality

The baking performance and gas retention capacity of wheat dough depends on production rate and total volume of CO₂ during fermentation. This study aims to examine the effect of the CO₂ formation kinetics and the gas volume fraction on the structural integrity of wheat dough and the resulting bread quality. The gas release characteristics were evaluated using a rheofermentometer with varied concentrations of compressed yeast and instant dry yeast (CY and IDY respectively). For this purpose, the maximum CO₂ formation rate was calculated through the derivation of hydrostatic pressure curves measured in the rheofermentometer. For CY, the time when gas escapes the dough matrix (Tx, time of porosity) as well as the corresponding gas volume depended on the gas formation rate, whereas the gas retention capacity of wheat dough leavened with IDY was not affected by the CO₂ formation rate. Although the dough leavened with IDY showed improved extensibility during fermentation, the specific bread volume was 21% below that of the samples leavened with CY. These results indicate that an increase in the maximum gas formation rate considerably affects the structural integrity of the dough matrix. Because of the reduction of the loaf volume, the effect is reinforced by the application of IDY.