Distribution and characterisation of fructan in wheat milling fractions

In vitro and ex vivo metabolism of chemically diverse fructans by bovine rumen Bifidobacterium and Lactobacillus species

BACKGROUND

Inulin and inulin-derived fructooligosaccharides (FOS) are well-known prebiotics for use in companion animals and livestock. The mechanisms by which FOS contribute to health has not been fully established. Further, the fine chemistry of fructan structures from diverse sources, such as graminan-type fructans found in cereal crops, has not been fully elucidated. New methods to study fructan structure and microbial responses to these complex carbohydrates will be key for evaluating the prebiotic potency of cereal fructans found in cattle feeds. As the rumen microbiome composition is closely associated with their metabolic traits, such as feed utilization and waste production, prebiotics and probiotics represent promising additives to shift the microbial community toward a more productive state.

RESULTS

Within this study, inulin, levan, and graminan-type fructans from winter wheat, spring wheat, and barley were used to assess the capacity of rumen-derived Bifidobacterium boum, Bifidobacterium merycicum, and Lactobacillus vitulinus to metabolize diverse fructans. Graminan-type fructans were purified and structurally characterized from the stems and kernels of each plant. All three bacterial species grew on FOS, inulin, and cereal crop fructans in pure cultures. L. vitulinus was the only species that could metabolize levan, albeit its growth was delayed. Fluorescently labelled polysaccharides (FLAPS) were used to demonstrate interactions with Gram-positive bacteria and confirm fructan metabolism at the single-cell level; these results were in agreement with the individual growth profiles of each species. The prebiotic potential of inulin was further investigated within naïve rumen microbial communities, where increased relative abundance of Bifidobacterium and Lactobacillus species occurred in a dose-dependent and temporal-related manner. This was supported by in situ analysis of rumen microbiota from cattle fed inulin. FLAPS probe derived from inulin and fluorescent in situ hybridization using taxon-specific probes confirmed that inulin interacts with Bifidobacteria and Lactobacilli at the single-cell level.

CONCLUSION

This research revealed that rumen-derived Bifidobacteria and Lactobacilli vary in their metabolism of structurally diverse fructans, and that inulin has limited prebiotic potential in the rumen. This knowledge establishes new methods for evaluating the prebiotic potential of fructans from diverse plant sources as prebiotic candidates for use in ruminants and other animals.

Challenges to Increasing Dietary Fiber in White Flour and Bread

Increasing the intake of dietary fiber from staple foods is a key strategy to improve the health of consumers. White bread is an attractive vehicle to deliver increased fiber as it is widely consumed and available to all socio-economic groups. However, fiber only accounts for about 4% of the dry weight of white flour and bread compared to 10-15% in whole grain bread and flour. We therefore discuss the challenges and barriers to developing and exploiting new types of wheat with high fiber content in white flour. These include defining and quantifying individual fiber components and understanding how they are affected by genetic and environmental factors. Rapid high throughput assays suitable for determining fiber content during plant breeding and in grain-utilizing industries are urgently required, while the impact of fiber amount and composition on flour processing quality needs to be understood. Overcoming these challenges should have significant effects on human health.

The agavins (Agave carbohydrates) story

Fructans, are carbohydrates defined as fructose-based polymers with countable degree of polymerization (DP) ranging so far from DP3 to DP60. There are different types of fructans depending on their molecular arrangement. They are categorized as linear inulins and levans, neoseries of inulin and levan, branched graminans, and highly branched neofructans, so called agavins (Agave carbohydrates). It is worth to note that agavins are the most recently described type of fructans and they are also the most complex ones. The complexity of these carbohydrates is correlated to their various isomers and degree of polymerization range, which is correlated to their multifunctional application in industry and human health. Here, we narrate the story of the agavins' discovery. This included their chemical characterization, their benefits, biotechnological applications, and drawbacks over human health. Finally, a perspective of the study of agavins and their interactions with other metabolites through metabolomics is proposed.

Gluten and Wheat in Women's Health: Beyond the Gut

Since the rise of awareness of gluten/wheat-related disorders in the academic and clinical field in the last few decades, misinformation regarding the gluten-free diet (GFD) and its impact on health has been spreading among the general population. Despite the established link between gluten and celiac disease (CD), where a GFD is mandatory to reach clinical and histological remission, things are more complicated when it comes to non-celiac gluten/wheat sensitivity (NCGWS) and other autoimmune/dysimmune disorders. In the last conditions, a beneficial effect of gluten withdrawal has not been properly assessed, but still is often suggested without strong supporting evidence. In this context, women have always been exposed, more than men, to higher social pressure related to nutritional behaviors and greater engagement in controlling body weight. With this narrative review, we aim to summarize current evidence on the adherence to a GFD, with particular attention to the impact on women's health.

Fructan Concentrations in Cooked Cereal Grains as a Nutritional Consideration for Low-FODMAP Diet

Grains, essential for maintaining good health, contain short-chain carbohydrates like fructans, which can contribute to disorders in some individuals. Understanding and managing these FODMAPs (fermentable oligo-, di-, and monosaccharides and polyols) are essential for enhanced dietary guidance and well-being. The primary objective of the study was to establish safe portion sizes for grains and rice within low-FODMAP diets. A comprehensive analysis of fructan levels in diverse commercial cereal products contributes to an understanding of the potential digestive impact of FODMAPs in grains and supporting enhanced dietary guidance for individuals with FODMAP-related disorders. Various grains, like white and brown rice, barley, wheat groats, and buckwheat, highlight the challenges of handling fructans in a low-FODMAP diet. Fructans to heat-induced degradation, as demonstrated in bulgur, emphasize the need to consider cooking methods for managing their intake. Identification of potentially safe grains, like white long-grain rice and arborio rice, is significant, but caution is advised with barley groats and couscous, stressing personalized dietary decisions. Correlation analyses linking color parameters, moisture content, and fructan levels in cooked grains reveal a positive relationship, suggesting water content's potential impact on fructan stability and grain hydration properties. In conclusion, the study provides valuable insights into the intricate details of FODMAPs in grains, supporting the development of dietary strategies that enhance both health and sensory satisfaction.

Increasing fibre in white flour and bread: Implications for health and processing

Dietary fibre is beneficial for human health, but dietary intakes are below recommended levels in most countries. Cereals are the major source of dietary fibre in Western diets, with bread providing about 20% of the daily intake in the United Kingdom. Despite the promotion of fibre-rich wholegrain products, white bread (which has a lower fibre content) remains dominant in many countries due to cultural preferences. Increasing the fibre content of white bread and other products made from white flour is therefore an attractive strategy for increasing fibre intake. This can be achieved by exploiting genetic variation in wheat without major effects on the processing quality or the consumer acceptability of products. Modelling data for food consumption in the United Kingdom shows that increasing the fibre content of white flour by 50% (from about 4% to 6% dry weight) and in wholegrain by 20% will increase total fibre intake by 1.04 g/day and 1.41 g/day in adult females and males, respectively. Furthermore, in vitro studies indicate that the increased fibre content of white bread should reduce the rate of starch digestion and glucose release in the human gastrointestinal tract.

Influence of Hydrothermal Treatment of Brewer's Spent Grain on the Concentration and Molecular Weight Distribution of 1,3-1,4-β-D-Glucan and Arabinoxylan

Brewer's spent grain (BSG) is the most abundant residual in the brewing process. Non-starch polysaccharides such as 1,3-1,4-β-D-glucan (β-glucan) and arabinoxylan (AX) with proven beneficial effects on human health remain in this by-product in high amounts. Incorporating the valuable dietary fiber into the food industry could contribute to a healthy diet. However, a major challenge is extracting these dietary fibers (i.e., β-glucan and AX) from the solid residue. In this study, hydrothermal treatment (HT) was applied to dissolve the remaining water-insoluble carbohydrates from BSG with the aim to extract high amounts of β-glucan and AX. Particular focus was placed on the molecular weight (MW) range above 50 kDa and 20 kDa, respectively, as these are considered to have health-promoting effects. Different treatment temperatures, reaction times, and internal reactor pressures were tested to determine the best process settings to achieve high yields of β-glucan and AX and to examine the influence on their molecular weight distribution (MWD). Overall, 85.1% β-glucan and 77.3% AX were extracted corresponding to 6.3 g per kg BSG at 160 °C and 178.3 g kg-1 at 170 °C, respectively. However, less than 20% of both fiber substances were in the desirable MW range above 50 kDa and 20 kDa, respectively. When lower temperatures of 140 and 150 °C were applied, yields of only 3.0 g kg-1 β-glucan and 128.8 g kg-1 AX were obtained, whereby the proportion of desirable fiber fractions increased up to 45%. Further investigations focused on the heat-induced degradation of monosaccharides and the formation of undesirable by-products (i.e., HMF and furfural) that might pose a health risk.

FODMAP reduction strategies for nutritionally valuable baking products: current state and future challenges

Fermentable oligo-, di- and monosaccharides and polyols (FODMAP) comprise several previously unrelated carbohydrates, such as fructans, fructo-oligosaccharides, galacto-oligosaccharides, fructose (in excess of glucose), mannitol and sorbitol, and among others. For many patients with gastro-intestinal disorders, such as irritable bowel syndrome, the ingestion of FODMAP triggers symptoms and causes discomfort. Among the main contributors to the dietary FODMAP intake are baking products, in particular bread as a major global staple food. This is primarily due to the fructan content of the cereal flours, but also process induced accumulation of FODMAP is possible. To provide low-FODMAP baking products, researchers have investigated various approaches, such as bio-process reduction by yeast, lactic acid bacteria, germination of the raw material or the use of exogenous enzymes. In addition, the selection of appropriate ingredients, which are either naturally or after pretreatment suitable for low-FODMAP products, is discussed. The sensory and nutritional quality of low-FODMAP baking products is another issue, that is addressed, with particular focus on providing sufficient dietary fiber intake. Based on this information, the current state of low-FODMAP baking and future research necessities, to establish practical strategies for low-FODMAP products, are evaluated in this article.

Strategies for Producing Low FODMAPs Foodstuffs: Challenges and Perspectives

In recent years, there has been a growing interest in a diet low in fermentable oligosaccharides, disaccharides, monosaccharides, and polyols (FODMAPs) as a promising therapeutic approach to reduce the symptoms associated with irritable bowel syndrome (IBS). Hence, the development of low FODMAPs products is an important challenge for the food industry, and among the various foodstuffs associated with the intake of FODMAPs, cereal-based products represent an issue. In fact, even if their content in FODMAPs is limited, their large use in diet can be an important factor in developing IBS symptoms. Several useful approaches have been developed to reduce the FODMAPs content in processed food products. Accurate ingredient selection, the use of enzymes or selected yeasts, and the use of fermentation steps carried out by specific lactic bacteria associated with the use of sourdough represent the technical approaches that have been investigated, alone or in combination, to reduce the FODMAPs content in cereal-based products. This review aims to give an overview of the technological and biotechnological strategies applicable to the formulation of low-FODMAPs products, specifically formulated for consumers affected by IBS. In particular, bread has been the foodstuff mainly investigated throughout the years, but information on other raw or processed products has also been reported. Furthermore, taking into account the required holistic approach for IBS symptoms management, in this review, the use of bioactive compounds that have a positive impact on reducing IBS symptoms as added ingredients in low-FODMAPs products is also discussed.

Natural Variation in the Content and Degree of Polymerization of Fructans in Wheat: Potential for Selection of Genotypes with Beneficial Health Composition

Fructans are important biocompounds because of their health-promoting effects as dietary fiber and prebiotics and also because of their harmful effects as fermentable oligosaccharides, disaccharides, monosaccharides, and polyols (FODMAP) particularly in people suffering from irritable bowel syndrome (IBS) and inflammatory bowel disease (IBD), and recently as potential triggers of non-celiac wheat/gluten sensitivity. In this work, we have analyzed the fructan contents as well as its degree of polymerization (DP) in a genetically diverse set of wheat varieties, modern and landraces, from different commonly consumed species (N = 124). A significant variation in fructan contents within and between species was observed, with the following relationship: Triticum aestivum (Landraces) > Triticum aestivum (Modern) ≥ Triticum turgidum (Modern) = T. turgidum (Landraces) ≥ Triticum spelta. In addition, a substantial part of the fructans (>50%) showed a DP ≤ 6. Considering that wheat is a major source of fructans, our results can contribute to a better nutritional management of our diets and be a basis for targeted wheat breeding to alter fructan contents.

Comparative study of sugar extraction procedures for HPLC analysis and proposal of an ethanolic extraction method for plant-based high-protein ingredients

BACKGROUND

The increasing importance of plant-based proteins in the food sector makes a reliable compositional analysis of plant-based high-protein ingredients a necessity. Specifically, the quantification of short-chain carbohydrates is relevant for multiple areas, including food product development, food labelling and fundamental food chemistry and food technology research. Commonly used extraction procedures for subsequent high-performance liquid chromatographic separation and quantification of short-chain carbohydrates have been discussed controversially regarding a range of complications that can potentially lead to inaccurate sugar determination. The present study compares the sugar levels in wheat flour and wholemeal wheat flour determined with different aqueous and ethanolic extraction procedures. These procedures included measures to prevent enzyme activity and microbial growth, which represent two of the most relevant challenges in sugar extraction from food samples.

RESULTS

Differences in sugar levels (sum of sucrose/maltose, glucose and fructose) as high as 1.8% dry matter (wheat flour) were observed between the employed extraction procedures. Ethanolic extraction (80% ethanol in ultrapure water) with the use of the antimicrobial agent sodium azide but without Carrez clarification was identified as most promising for sugar determination in plant-based high-protein ingredients.

CONCLUSION

A screening of high-protein ingredients derived from cereals (wheat gluten), pseudocereals (quinoa, amaranth, buckwheat) and legumes (soy, pea, lupin, lentil, carob, chickpea, faba bean) concerning their levels of sucrose, maltose, glucose and fructose confirmed the applicability of the chosen extraction procedure. © 2021 Society of Chemical Industry.

Comparative characterization of the gluten and fructan contents of breads from industrial and artisan bakeries: a study of food products in the Spanish market

Background

The consumption of wheat/gluten is associated with adverse reactions for human health. Gluten and fructans are identified as the major compounds triggering and worsening adverse reactions to wheat, which are increasing, and as a consequence, avoidance of gluten/wheat is the common strategy of many individuals of the western population. Although bread is a product of daily consumption, there is a lack of information on the gluten and fructan contents and the influence of artisanal or industrial processes.

Objective

The aim of this study is to carry out a comparative characterization between artisan bakeries and hypermarkets in Spain for gluten and fructan contents in daily sold breads.

Design

A total of 48 types of bread highly consumed in Spain sold in artisan bakeries (long fermentation) and hypermarkets (short fermentations) were selected for comparing the gluten and fructan contents. Methods such as reverse phase-high performance liquid chromatography (RP-HPLC), R5 monoclonal antibody (moAb), and fructans protocols were used for the quantification of these compounds.

Results

Great variation for the content of gluten and fructans has been found between all bread categories. Although breads produced using long fermentation (artisan bakeries) contain significantly lower gluten, they have higher fructans than those using short fermentations (hypermarkets). Durum wheat breads had the lowest content of gluten. Moreover, spelt breads from artisan bakeries had the lowest content of fructans but not those from hypermarkets.

Discussion

In this study, we report the comparative characterizarion of the breads of the Spanish market. These food products presented variation in the amount of gluten and fructans, ligated in most of the cases to the nature of the providers: artisan bakeries against hypermarkets. Depending on the type of bread, the differences for the daily consumption of gluten and fructan can be 4.5 and 20 times, respectively.

Conclusions

We found strong differences for gluten and fructan contents among breads. These information may contribute to designing strategies to improve the management of gluten and fructans in bread.

Bioprocessing of Wheat and Amaranth Bran for the Reduction of Fructan Levels and Application in 3D-Printed Snacks

Bran can enrich snacks with dietary fibre but contains fructans that trigger symptoms in people with irritable bowel syndrome (IBS). This study aimed to investigate the bioprocessing of wheat and amaranth bran for degrading fructans and its application (at 20% flour-based) in 3D-printed snacks. Bran was bioprocessed with Saccharomyces cerevisiae alone or combined with inulinase, Kluyveromyces marxianus, Limosilactobacillus fermentum, or commercial starter LV1 for 24 h. Fructans, fructose, glucose, and mannitol in the bran were analysed enzymatically. Dough rheology, snack printing precision, shrinkage in baking, texture, colour, and sensory attributes were determined. The fructan content of wheat bran was 2.64% dry weight, and in amaranth bran, it was 0.96% dry weight. Bioprocessing reduced fructan content (up to 93%) depending on the bran type and bioprocessing agent, while fructose and mannitol remained below the cut-off value for IBS patients. Bran bioprocessing increased the complex viscosity and yield stress of dough (by up to 43 and 183%, respectively) in addition to printing precision (by up to 13%), while it lessened shrinkage in baking (by 20-69%) and the hardness of the snacks (by 20%). The intensity of snack sensory attributes depended on the bran type and bioprocessing agent, but the liking ("neither like nor dislike") was similar between samples. In conclusion, snacks can be enriched with fibre while remaining low in fructans by applying bioprocessed wheat or amaranth bran and 3D printing.

FODMAP modulation as a dietary therapy for IBS: Scientific and market perspective

A diet low in fermentable oligosaccharides, disaccharides, monosaccharides, and polyols (FODMAPs) is a promising therapeutic approach to reduce gastrointestinal symptoms associated with irritable bowel syndrome (IBS). However, a shift toward a more sustainable, healthy diet with higher inclusion of whole-grain cereals (i.e., wheat, rye, barley) and pulses, naturally rich in FODMAPs, poses a severe challenge for susceptible individuals. Dietary restriction of fermentable carbohydrates (commonly called the "low FODMAP diet") has received significant consideration. Hence, the development of functional low FODMAP products is emerging in food science and the food industry. In this review, we evaluate the most promising yet neglected (bio)-technological strategies adopted for modulating the FODMAP contents in complex food systems and the extent of their uptake in the global food market. We extensively investigated the global low FODMAP market, contrasted with the status quo in food science and discussed the key principles and concomitant challenges of targeted FODMAP reduction strategies. Powerful tools are available which are based either on the use of ingredients where FODMAPs have been physically removed (e.g., by membrane filtration) or biotechnologically reduced during the food processing, mediated by added enzymes, microbial enzymes during a fermentation process, and seed endogenous enzymes. However, <10% of the small market of functional products with a low FODMAP claim (total ∼800 products) used any of the targeted FODMAP reduction techniques. The global market is currently dominated by gluten-free products, which are naturally low in FODMAPs and characterized by inferior sensory attributes.

Process-Induced Changes in the Quantity and Characteristics of Grain Dietary Fiber

Daily use of wholegrain foods is generally recommended due to strong epidemiological evidence of reduced risk of chronic diseases. Cereal grains, especially the bran part, have a high content of dietary fiber (DF). Cereal DF is an umbrella concept of heterogeneous polysaccharides of variable chemical composition and molecular weight, which are combined in a complex network in cereal cell walls. Cereal DF and its distinct components influence food digestion throughout the gastrointestinal tract and influence nutrient absorption and other physiological reactions. After repeated consumption of especially whole grain cereal foods, these effects manifest in well-demonstrated health benefits. As cereal DF is always consumed in the form of processed cereal food, it is important to know the effects of processing on DF to understand, safeguard and maximize these health effects. Endogenous and microbial enzymes, heat and mechanical energy during germination, fermentation, baking and extrusion destructurize the food and DF matrix and affect the quantity and properties of grain DF components: arabinoxylans (AX), beta-glucans, fructans and resistant starch (RS). Depolymerization is the most common change, leading to solubilization and loss of viscosity of DF polymers, which influences postprandial responses to food. Extensive hydrolysis may also remove oligosaccharides and change the colonic fermentability of DF. On the other hand, aggregation may also occur, leading to an increased amount of insoluble DF and the formation of RS. To understand the structure–function relationship of DF and to develop foods with targeted physiological benefits, it is important to invest in thorough characterization of DF present in processed cereal foods. Such understanding also demands collaborative work between food and nutritional sciences.

Prebiotic Potential of Cereal Components

One type of functional food that has been receiving much attention is food rich in prebiotics. The old but still valid definition of prebiotics defines them as non-digestible food components that selectively stimulate the growth and/or activity of the beneficial bacteria in the colon and, as a result, improve the host health. Cereals, as one of the main components in the human diet, contain substantial levels of dietary fiber with probable prebiotic potential. In addition, dietary fiber, particularly soluble dietary fiber, has recently emerged as a promising natural highly functional food ingredient in food production. This review focuses on the prebiotic potential of cereal dietary fiber types and covers the achievements and developments regarding its isolation. First, the probiotic and prebiotic concepts will be discussed. Next, different components of dietary fiber and their effect on the host bacteria through in vitro and/or in vivo studies will be reviewed. In a last part, this paper also discusses means of boosting the prebiotic properties of cereal components and innovative strategies for the extraction of cereal dietary fiber. The review focuses on wheat as a leading cereal crop that is widely and intensely used throughout the world in food production.

Investigation of different dietary-fibre-ingredients for the design of a fibre enriched bread formulation low in FODMAPs based on wheat starch and vital gluten

Consumption of fermentable oligo-, di-, monosaccharides and polyols (FODMAPs) often induces symptoms of irritable bowel syndrome (IBS). Since FODMAPs and dietary fibre (DF) share certain characteristics, IBS-patients have a limited intake of DF. Therefore, enrichment of a low FODMAP model bread (based on 84% wheat starch and 16% vital gluten) with various fibres (bamboo, cellulose, psyllium, guar gum) in two different concentrations (3 g/100 g and 6 g/100 g) was investigated. Physico-chemical properties of doughs and breads were analysed (fermentation quality, gluten development, specific volume and hardness), as well as the release of reducing sugars during in vitro digestion. High performance anion exchange chromatography with coupled pulsed amperometric detection (HPAEC-PAD) was used to determine the FODMAP levels (contents of mannitol, sorbitol, fructose in excess of glucose, fructans and α-galactooligosaccharides) of both dough and bread. Prototypes were compared with wheat flour-based breads (bakers’ flour with and without wheat bran addition) to assess the performance of these prototypes. Prototypes showed a decreased quality compared to a baker’s flour control, however, a quality comparable to commercial wheat bran breads was found. This in combination with a lower release of reducing sugars during in vitro digestion underline the potential of fibre enriched breads as part of a healthier and more palateable low FODMAP diet. Furthermore, this study highlights the importance of the type (viscous and insoluble) and the concentration of fibres used. Application of psyllium in a concentration of 3 g/100 g showed the most beneficial impact on both physical (specific volume, hardness after 0 h and 24 h) and nutritional aspects of bread.

Genome-wide association study reveals the genetic complexity of fructan accumulation patterns in barley grain

We profiled the grain oligosaccharide content of 154 two-row spring barley genotypes and quantified 27 compounds, mainly inulin- and neoseries-type fructans, showing differential abundance. Clustering revealed two profile groups where the 'high' set contained greater amounts of sugar monomers, sucrose, and overall fructans, but lower fructosylraffinose. A genome-wide association study (GWAS) identified a significant association for the variability of two fructan types: neoseries-DP7 and inulin-DP9, which showed increased strength when applying a novel compound ratio-GWAS approach. Gene models within this region included three known fructan biosynthesis genes (fructan:fructan 1-fructosyltransferase, sucrose:sucrose 1-fructosyltransferase, and sucrose:fructan 6-fructosyltransferase). Two other genes in this region, 6(G)-fructosyltransferase and vacuolar invertase1, have not previously been linked to fructan biosynthesis and showed expression patterns distinct from those of the other three genes, including exclusive expression of 6(G)-fructosyltransferase in outer grain tissues at the storage phase. From exome capture data, several single nucleotide polymorphisms related to inulin- and neoseries-type fructan variability were identified in fructan:fructan 1-fructosyltransferase and 6(G)-fructosyltransferase genes. Co-expression analyses uncovered potential regulators of fructan biosynthesis including transcription factors. Our results provide the first scientific evidence for the distinct biosynthesis of neoseries-type fructans during barley grain maturation and reveal novel gene candidates likely to be involved in the differential biosynthesis of various types of fructan in barley.

Determination of FODMAP contents of common wheat and rye breads and the effects of processing on the final contents

The benefits of a diet, low in fermentable oligo-, di- and monosaccharides and polyols (FODMAP) for patients suffering from irritable bowel syndrome (IBS) has been well established. Thus, the exact knowledge of the amount and composition of FODMAPs in foods is of vital importance for these patients. This study investigated the possibilities of FODMAP reduction by adjusting the processing parameters, which are feasible in practise, while still producing marketable breads. Therefore, the impact of prolonged proofing and the addition of sourdough on the FODMAPs in the final products was evaluated. High performance anion exchange chromatography was used for qualitative and quantitative analysis. A prolonged proofing time resulted in reduction of the fructan content and in consequence of the total FODMAPs. In contrast, the addition of sourdough only altered the FODMAP composition, by reducing the fructan content but increasing the mannitol content. While all the breads produced from refined wheat flour meet the low-FODMAP criteria, the breads from rye and whole meal wheat flour have to be considered as high-FODMAP, regardless of the processing conditions investigated. Breads produced from rye flour exceeded the limits for fructans and mannitol, while whole meal wheat breads were found to exceed the threshold for excess fructose. Overall, the production of low-FODMAP rye breads was identified as the biggest challenge for future research, since it could not be achieved using conventional processing parameter.

The Two Faces of Wheat

Wheat-based foods have been staple foods since about 10,000 years and constitute a major source of energy, dietary fiber, and micronutrients for the world population. The role of wheat in our diet, however, has recently been scrutinized by pseudoscientific books and media reports promoting the overall impression that wheat consumption makes people sick, stupid, fat, and addicted. Consequently, numerous consumers in Western countries have started to question their dietary habits related to wheat consumption and voluntarily decided to adopt a wheat-free diet without a medical diagnosis of any wheat-related disorder (WRD), such as celiac disease, wheat allergy, or non-celiac gluten sensitivity. The aim of this review is to achieve an objective judgment of the positive aspects of wheat consumption as well as adverse effects for individuals suffering from WRDs. The first part presents wheat constituents and their positive nutritional value, in particular, the consumption of products from whole-grain flours. The second part is focused on WRDs that affect predisposed individuals and can be treated with a gluten-free or -reduced diet. Based on all available scientific knowledge, wheat consumption is safe and healthy for the vast majority of people. There is no scientific evidence to support that the general population would benefit from a wheat-free diet.

Presence of Fermentable Oligo-, Di-, Monosaccharides, and Polyols (FODMAPs) in commonly eaten foods: extension of a database to indicate dietary FODMAP content and calculation of intake in the general population from food diary data

Background

FODMAPs (Fermentable Oligo-, Di-, Monosaccharides And Polyols) are known for their health benefits but their fermentation may trigger gastrointestinal symptoms and a low-FODMAP diet is a commonly used intervention for functional gastrointestinal disorders. The use of direct measures of FODMAP is labor intensive and expensive and to facilitate the assessment of FODMAP intake in research and clinical work, a nutritional content database with good quality estimates on FODMAP values is needed. Further, the average intake of FODMAP in a general population would be a useful reference and knowledge of the most commonly eaten foods containing FODMAPs would facilitate clinical work utilizing FODMAP diet interventions.

Methods

A nutritional content database was extended with published FODMAP content data. The database was used to calculate FODMAP intake from four-day food diaries from 117 individuals from the general population in Sweden and the most common food items containing FODMAPs were identified.

Results

FODMAP content for 1060 food items was added to the database resulting in 1805 listed FODMAP values. Mean intake of total FODMAP in the diaries was 19 g (fructose: 15.2 g; fructan: 3.5 g; lactose: 14.1 g; galacto-oligosaccharides (GOS) 0.43 g and polyols 1.3 g per day). Overall the most common eaten food items containing FODMAPs were rye and wheat based foods.

Conclusion

Intake of FODMAPs as calculated using the extended database were in line with previous studies supporting its use of the database in both research and clinical interventions. The lists of the most commonly eaten FODMAP food items are provided and may be used to facilitate FODMAP diet interventions.

Strategies to improve wheat for human health

Despite their economic importance and growing demand, concerns are emerging around wheat-based foods and human health. Most wheat-based foods are made from refined white flour rather than wholemeal flour, and the overconsumption of these products may contribute to the increasing global prevalence of chronic diseases, particularly type 2 diabetes and obesity. Here, we review how the amount, composition and interactions of starch and cell wall polysaccharides, the major carbohydrate components in refined wheat products, impact human health. We discuss strategies and challenges to manipulate these components for improved diet and health using newly developed wheat genomics tools and resources. Commercial foods developed from these novel approaches must be produced without adverse effects on cost, consumer acceptability and processing properties.

Arabinoxylan content and grain tissue distribution are good predictors of the dietary fibre content and their nutritional properties in wheat products

Wheat millstreams and wheat-based foods (pasta, biscuits and bread) enriched or not in dietary fibre with fractions extracted from wheat grains, have been characterized either for their total dietary fibre content (TDF) and their arabinoxylan (AX) content. A strong correlation (r² = 0.98) is observed between the AX and TDF contents indicating that AX can be used to estimate TDF content in wheat products. Moreover, by adding a previous step including enzymatic hydrolysis with a xylanase, a functional evaluation of DF is proposed based on the amount of AX released by the enzyme. Xylanase hydrolysable AX are likely also released by microbiota's enzymes in the gut and therefore an indicator for the proportion of fermentable DF in grain fractions and wheat-based foods (pasta, biscuits and bread). This assay opens the door for simple characterization of qualitative attribute of cereal DF.

Variability in yeast invertase activity determines the extent of fructan hydrolysis during wheat dough fermentation and final FODMAP levels in bread

Consumption of fructan-containing cereal products is considered beneficial for most people, but not for those suffering from irritable bowel syndrome (IBS), as they should avoid the consumption of fermentable oligosaccharides, disaccharides, monosaccharides and polyols (acronym: FODMAP). Controlling fructan levels in cereal products is not trivial. However, controlling yeast invertase-mediated hydrolysis of fructan during dough fermentation might offer a handle to modulate fructan concentrations. In this work, the variability in invertase activity and substrate specificity in an extensive set of industrial Saccharomyces cerevisiae strains is investigated. Analysis showed a high variability in the capacity of these strains to hydrolyse sucrose and fructo-oligosaccharides. Industrial yeast strains with a high activity towards fructo-oligosaccharides efficiently reduced wheat grain fructans during dough fermentation to a final fructan level of 0.3% dm, whereas strains with a low invertase activity yielded fructan levels around 0.6% dm. The non-bakery strains produced lower levels of CO₂ in fermenting dough resulting in lower loaf volumes. However, CO₂ production and loaf volume could be increased by the addition of 3% glucose. In conclusion, this study shows that variation in yeast invertase activity and specificity can be used to modulate the fructan content in bread, allowing the production of low FODMAP breads, or alternatively, breads with a higher soluble dietary fibre content.

Comparative prebiotic activity of mixtures of cereal grain polysaccharides

The main components of the non-starch polysaccharide (NSP) fraction of wheat flour are arabinoxylan (AX) and β-glucan. These are also present in other cereal grains, but their proportions vary with AX being the major component in wheat and rye and β-glucan in barley and oats. Therefore, it was hypothesised that these NSPs could act synergistically when fermented in vitro at the ratios present in the major foods consumed, resulting in increased prebiotic activity. AX and β-glucan were therefore tested in in vitro fermentation studies to assess their prebiotic activity when used individually and/or in different ratios. Short-chain fatty-acids (SCFAs) produced from in vitro fermentation were measured using HPLC and bacterial populations were measured using flow cytometry with fluorescence in situ hybridisation (Flow-FISH). Fermentation of AX alone resulted in a significant bifidogenic activity and increased concentrations of SCFAs, mainly acetate, after 8-24 h of fermentation, however β-glucan alone did not show prebiotic activity. The greatest prebiotic activity, based on concentration of total SCFAs and increases in total bacteria as well as beneficial Bifidobacterium and Clostridium coccoides/Eubacterium groups, was observed when AX and β-glucan were combined at a 3:1 ratio, which corresponds to their ratios in wheat flour which is major source of cereal fibre in the diet. This indicates that the population of bacteria in the human GI tract may be modulated by the composition of the fibre in the diet, to maximise the prebiotic potential.

Technological Methods for Reducing the Content of Fructan in Wheat Bread

Irritable bowel syndrome (IBS) is a functional disorder of the gastrointestinal system. Adherence to a low-FODMAP (fermenting oligosaccharides, disaccharides, monosaccharides, and polyols) diet may be one of the solutions in this case. The major FODMAP carbohydrates found in wheat bread are fructans. The objective of this study was to produce wheat bread with a reduced fructans content. Breads were made from light and whole grain flour obtained from common wheat using two methods of dough development-I-stage method with the use of yeast, and II-stage method with the use of yeast and sourdough with a pure culture of Lactobacillus plantarum. Four different fermentation times were tested-60, 90, 120, and 150 min. Afterwards, quality attributes (loaf volume, crust and crumb color, and sensory properties) of the produced breads were evaluated, and the fructans content was determined. The results demonstrated that all the factors influenced the quality of wheat breads, as well as their fructans content. Breads made with the II-stage method and light flour had a lower content of fructans, which was decreased in breads along with extending the time of dough fermentation. The greatest impact on fructans content decrease in wheat bread was ascribed to the use of light flour, the II-stage method of dough development coupled with a dough fermentation time prolongation to 150 min.

Optimization and Validation of an HPAEC-PAD Method for the Quantification of FODMAPs in Cereals and Cereal-Based Products

This study presents an analytical method for the quantification of fermentable oligo-, di-, and monosaccharides and polyols (FODMAPs) in cereals and cereal-based products, considering diverse ingredients, such as different cereals in addition to wheat, pulses, or pseudocereals. All carbohydrates have been separated, identified, and quantified with a high-performance anion-exchange chromatographic system coupled with a pulsed amperometric detection (HPAEC-PAD). The total fructan content and the average degree of polymerization (DP_av) have been determined after enzymatic hydrolysis to the monomers glucose and fructose, on the basis of the principle of the official method for fructan quantification in food products, AOAC 997.08. The methods for extraction, separation, and detection as well as fructan determination are based on several other studies and were modified in order to minimize interferences in the analysis. The method has been validated with regard to the limits of detection and quantification, the linearity, the repeatability, and the accuracy as well as the DP_av of the fructans.

Enzymatic analysis of levan produced by lactic acid bacteria in fermented doughs

Levans and inulins are fructans with mainly β-(2→6) and β-(2→1) linkages, respectively. Levans are produced by many lactic acid bacteria, e.g. during sourdough fermentation. Levans have shown prebiotic properties and may also function as in situ-produced hydrocolloids. So far, levan contents have been measured by acid hydrolysis, which cannot distinguish levans from e.g. inulins. In order to develop a specific analysis for levan in food matrices, a Paenibacillus amylolyticus endolevanase was combined with exoinulinase for levan hydrolysis. A separate endoinulinase treatment was used to detect the possible presence of inulin. Interfering sugars were removed by a pre-wash with aqueous ethanol. Levan content was estimated from fructose and glucose released in the hydrolysis, with a correction made for the residual fructose and glucose-containing sugars. The method was validated using wheat model doughs spiked with commercial Erwinia levan, and tested by analyzing levan content in Leuconostoc mesenteroides DSM 20343-fermented fava bean doughs.

Applicability of Yeast Fermentation to Reduce Fructans and Other FODMAPs

A diet low in fermentable oligosaccharides, disaccharides, monosaccharides and, polyols (FODMAPs) is recommended for people affected by irritable bowel syndrome (IBS) and non-coeliac wheat sensitivity (NCWS) in order to reduce symptoms. Therefore, the aim of this study was to evaluate the impact of 13 sourdough-related yeasts on FODMAP degradation, especially fructans. First, a model system containing a typical wheat carbohydrate profile was applied to evaluate the growth rate of each yeast strain. Additionally, changes in the sugar composition, for up to four days, were monitored by high-pressure anion-exchange chromatography (HPAEC). A more realistic approach with a wheat flour suspension was used to characterize CO₂ production according to the Einhorn method. The reduction of the total fructans was analyzed using an enzymatic method. Furthermore, a fingerprint of the present fructans with different degrees of polymerization was analyzed by HPAEC. The results revealed strong differences in the examined yeast strains' ability to degrade fructans, in both the model system and wheat flour. Overall, Saccharomycescerevisiae isolated from Austrian traditional sourdough showed the highest degree of degradation of the total fructan content and the highest gas building capacity, followed by Torulasporadelbrueckii. Hence, this study provides novel knowledge about the FODMAP conversion of yeast strains.

Use of Sourdough in Low FODMAP Baking

A low FODMAP (fermentable oligosaccharides, disaccharides, monosaccharides, and polyols) diet allows most irritable bowel syndrome (IBS) patients to manage their gastrointestinal symptoms by avoiding FODMAP-containing foods, such as onions, pulses, and products made from wheat or rye. The downside of a low FODMAP diet is the reduced intake of dietary fiber. Applying sourdoughs—with specific FODMAP-targeting metabolic properties—to wholegrain bread making can help to remarkably reduce the content of FODMAPs in bread without affecting the content of the slowly fermented and well-tolerated dietary fiber. In this review, we outline the metabolism of FODMAPs in conventional sourdoughs and outline concepts related to fructan and mannitol metabolism that allow development of low FODMAP sourdough bread. We also summarize clinical studies where low FODMAP but high fiber, rye sourdough bread was tested for its effects on gut fermentation and gastrointestinal symptoms with very promising results. The sourdough bread-making process offers a means to develop natural and fiber-rich low FODMAP bakery products for IBS patients and thereby help them to increase their dietary fiber intake.

Kluyveromyces marxianus yeast enables the production of low FODMAP whole wheat breads

There is evidence that a diet low in Fermentable Oligo-, Di-, Monosaccharides And Polyols (FODMAPs) alleviates symptoms in approx. 70% of the patients suffering from irritable bowel syndrome. Through fructans, wheat containing products are a major source of FODMAPs in the western diet. Although fructans are partially degraded during dough fermentation by Saccharomyces cerevisiae invertase, wheat bread contains notable fructan levels. In this study, it was shown that Kluyveromyces marxianus strain CBS6014 can degrade more than 90% of the fructans initially present in wheat whole meal during bread making, which can be attributed to its high inulinase activity. As K. marxianus CBS6014 was not able to consume maltose during fermentation, alternative sugars (sucrose) or glucose releasing enzymes (amyloglucosidase) had to be included in the bread making recipe to ensure sufficient production of CO₂ and high bread quality. Five volatile flavor compounds were produced in significantly different levels when K. marxianus CBS6014 was used as starter culture compared with the conventional S. cerevisiae bakery strain. These differences were, however, not detected when sensory analysis of the crumb was performed. This study demonstrates the potential of inulinase-producing K. marxianus strains for the production of (whole meal) breads low in FODMAPs.

The Overlapping Area of Non-Celiac Gluten Sensitivity (NCGS) and Wheat-Sensitive Irritable Bowel Syndrome (IBS): An Update

Gluten-related disorders have recently been reclassified with an emerging scientific literature supporting the concept of non-celiac gluten sensitivity (NCGS). New research has specifically addressed prevalence, immune mechanisms, the recognition of non-immunoglobulin E (non-IgE) wheat allergy and overlap of NCGS with irritable bowel syndrome (IBS)-type symptoms. This review article will provide clinicians with an update that directly impacts on the management of a subgroup of their IBS patients whose symptoms are triggered by wheat ingestion.

Saccharomyces cerevisiae and Kluyveromyces marxianus Cocultures Allow Reduction of Fermentable Oligo-, Di-, and Monosaccharides and Polyols Levels in Whole Wheat Bread

Fermentable oligo-, di-, and monosaccharides and polyols (FODMAPs) are small molecules that are poorly absorbed in the small intestine and rapidly fermented in the large intestine. There is evidence that a diet low in FODMAPs reduces abdominal symptoms in approximately 70% of the patients suffering from irritable bowel syndrome. Wheat contains relatively high fructan levels and is therefore a major source of FODMAPs in our diet. In this study, a yeast-based strategy was developed to reduce FODMAP levels in (whole wheat) bread. Fermentation of dough with an inulinase-secreting Kluyveromyces marxianus strain allowed to reduce fructan levels in the final product by more than 90%, while only 56%  reduction was achieved when a control Saccharomyces cerevisiae strain was used. To ensure sufficient CO₂ production, cocultures of S. cerevisiae and K. marxianus were prepared. Bread prepared with a coculture of K. marxianus and S. cerevisiae had fructan levels ≤0.2% dm, and a loaf volume comparable with that of control bread. Therefore, this approach is suitable to effectively reduce FODMAP levels in bread.

Exploitation of Old Wheat Properties for Prevention of Human Disease

Cereals occupy an important place in the Mediterranean diet pyramid and carbohydrates derived from whole grains seem to exert a beneficial role. In this context, some ancient wheat varieties such as khorasan wheat ( Triticum turgidum ssp. turanicum) may offer unique nutritional and functional properties to prevent human disease. The current paper reviews specific features of dietary carbohydrates focussing the attention on khorasan wheat and its major potential health benefits once regularly introduced in the diet.

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.

Establishing the relative importance of damaged starch and fructan as sources of fermentable sugars in wheat flour and whole meal bread dough fermentations

It is generally believed that maltose drives yeast-mediated bread dough fermentation. The relative importance of fructose and glucose, released from wheat fructan and sucrose by invertase, compared to maltose is, however, not documented. This is surprising given the preference of yeast for glucose and fructose over maltose. This study revealed that, after 2h fermentation of wheat flour dough, about 44% of the sugars consumed were generated by invertase-mediated degradation of fructan, raffinose and sucrose. The other 56% were generated by amylases. In whole meal dough, 70% of the sugars consumed were released by invertase activity. Invertase-mediated sugar release seems to be crucial during the first hour of fermentation, while amylase-mediated sugar release was predominant in the later stages of fermentation, which explains why higher amylolytic activity prolonged the productive fermentation time only. These results illustrate the importance of wheat fructan and sucrose content and their degradation for dough fermentations.