LC-MS analysis reveals the presence of graminan- and neo-type fructans in wheat grains

Quality characteristics of cereal-based foods enriched with different degree of polymerization inulin: A review

Vegetables, cereals and fruit are foods rich in fibre with beneficial and nutritional effects as their consumption reduces the onset of degenerative diseases, especially cardiovascular ones. Among fibres, inulin, oligofructose or fructooligosaccharide (FOS) are the best-studied. Inulin is a generic term to cover all linear β(2-1) fructans, with a variable degree of polymerization. In this review a better understanding of the importance of the degree of polymerization of inulin as a dietary fibre, functions, health benefits, classifications, types and its applications in the food industry was considered in different fortified foods. Inulin has been used to increase the nutritional and healthy properties of the product as a sweetener and as a substitute for fats and carbohydrates, improving the nutritional value and decreasing the glycemic index, with the advantage of not compromising taste and consistency of the product. Bifidogenic and prebiotic effects of inulin have been well established, inulin-type fructans are fermented by the colon to produce short-chain fatty acids, with important local and systemic actions. Addition of inulin with different degrees of polymerization to daily foods for the production of fortified pasta and bread was reviewed, and the impact on sensorial, technological and organoleptic characteristics even of gluten-free bread was also reported.

Modified fructan accumulation through overexpression of wheat fructan biosynthesis pathway fusion genes Ta1SST:Ta6SFT

BACKGROUND

Fructans are water-soluble carbohydrates that accumulate in wheat and are thought to contribute to a pool of stored carbon reserves used in grain filling and tolerance to abiotic stress.

RESULTS

In this study, transgenic wheat plants were engineered to overexpress a fusion of two fructan biosynthesis pathway genes, wheat sucrose: sucrose 1-fructosyltransferase (Ta1SST) and wheat sucrose: fructan 6-fructosyltransferase (Ta6SFT), regulated by a wheat ribulose-1,5-bisphosphate carboxylase/oxygenase small subunit (TaRbcS) gene promoter. We have shown that T4 generation transgene-homozygous single-copy events accumulated more fructan polymers in leaf, stem and grain when compared in the same tissues from transgene null lines. Under water-deficit (WD) conditions, transgenic wheat plants showed an increased accumulation of fructan polymers with a high degree of polymerisation (DP) when compared to non-transgenic plants. In wheat grain of a transgenic event, increased deposition of particular fructan polymers such as, DP4 was observed.

CONCLUSIONS

This study demonstrated that the tissue-regulated expression of a gene fusion between Ta1SST and Ta6SFT resulted in modified fructan accumulation in transgenic wheat plants and was influenced by water-deficit stress conditions.

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.

Screening and Application of Novel Homofermentative Lactic Acid Bacteria Results in Low-FODMAP Whole-Wheat Bread

FODMAPs are fermentable oligo-, di-, monosaccharides, and polyols. The application of homofermentative lactic acid bacteria (LAB) has been investigated as a promising approach for producing low-FODMAP whole-wheat bread. The low-FODMAP diet is recommended to treat irritable bowel syndrome (IBS). Wheat flour is staple to many diets and is a significant source of fructans, which are considered FODMAPs. The reduction of fructans via sourdough fermentation, generally associated with heterofermentative lactic acid bacteria (LAB), often leads to the accumulation of other FODMAPs. A collection of 244 wild-type LAB strains was isolated from different environments and their specific FODMAP utilisation profiles established. Three homofermentative strains were selected for production of whole-wheat sourdough bread. These were Lactiplantibacillus plantarum FST1.7 (FST1.7), Lacticaseibacillus paracasei R3 (R3), and Pediococcus pentosaceus RYE106 (RYE106). Carbohydrate levels in flour, sourdoughs (before and after 48 h fermentation), and resulting breads were analysed via HPAEC-PAD and compared with whole-wheat bread leavened with baker’s yeast. While strain R3 was the most efficient in FODMAP reduction, breads produced with all three test strains had FODMAP content below cut-off levels that would trigger IBS symptoms. Results of this study highlighted the potential of homofermentative LAB in producing low-FODMAP whole-wheat bread.

Preparation, Structural Characterisation, and Bioactivities of Fructans: A Review

Polysaccharides are important components of higher plants and have attracted increasing attention due to their many nutraceutical benefits in humans. Fructans, heterogeneous fructose polymers that serve as storage carbohydrates in various plants, represent one of the most important types of natural polysaccharides. Fructans have various physiological and therapeutic effects, which are beneficial to health, and have the ability to prevent or treat various diseases, allowing their wide use in the food, nutraceutical, and pharmaceutical industries. This article reviews the occurrence, metabolism, preparation, characterisation, analysis, and bioactivity of fructans. Further, their molecular weight, monosaccharide composition, linkages, and structural determination are described. Taken together, this review provides a theoretical foundation for further research into the structure-function relationships of fructans, as well as valuable new information and directions for further research and application of fructans in functional foods.

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.

Multi-constituents variation in medicinal crops processing: Investigation of nine cycles of steam-sun drying as the processing method for the rhizome of Polygonatum cyrtonema

The rhizome of Polygonatum cyrtonema (Polygonati Rhizoma) is widely consumed as medicine-homology-food in Asia for its tonic effect, which can be enhanced by traditional steam-sun drying for nine cycles. However, the multi-constituents variation in this process was unclear, and the necessity of nine cycles should be further discussed. In this study, the multiple constituents, including saccharides, amino acids, nucleosides and bases, lipids, saponins, homoisoflavones and cinnamamides, in P. cyrtonema treated with sun drying, heated air drying, each cycle of steam-heated air drying, infrared drying and microwave drying were compared. The results showed that the content of total saccharides increased in samples from one to four cycles of steam-heated air drying (365.0-945.6 mg/g) and decreased from four to nine (945.6-288.0 mg/g). The content of fructose increased in samples from one to six cycles (29.9-234.7 mg/g) and decreased from six to nine (234.7-177.7 mg/g). The abundance of most phospholipids and free fatty acids increased continuously from one to nine cycles while most of the amino acids, nucleosides and bases showed continuous declining trend. Principal component analysis showed that the samples treated with one to four cycles were wider in distance than four to nine, indicating the chemical composition tending to be stable after fourth steaming. If taking total saccharides, fructose, and phospholipids as the major quality indicator, four cycles of steam-heated air drying processing should be the ideal postharvest processing method to obtain better taste, flavor and functionality. Samples treated with heated-air drying and infrared drying were far in distance from steaming ones by hierarchical cluster analysis, which means these processing methods were not suitable to replace the traditional steam-sun drying process. Collectively, the above results will not only provide novel processing methods that will obtain the high active ingredients for P. cyrtonema, but also shed light on the optimization of processing technology for the industrial production of medicinal crops which need nine cycles of steam-sun drying processing.

Fructan Structure and Metabolism in Overwintering Plants

In northern regions, annual and perennial overwintering plants such as wheat and temperate grasses accumulate fructan in vegetative tissues as an energy source. This is necessary for the survival of wintering tissues and degrading fructan for regeneration in spring. Other types of wintering plants, including chicory and asparagus, store fructan as a reserve carbohydrate in their roots during winter for shoot- and spear-sprouting in spring. In this review, fructan metabolism in plants during winter is discussed, with a focus on the fructan-degrading enzyme, fructan exohydrolase (FEH). Plant fructan synthase genes were isolated in the 2000s, and FEH genes have been isolated since the cloning of synthase genes. There are many types of FEH in plants with complex-structured fructan, and these FEHs control various kinds of fructan metabolism in growth and survival by different physiological responses. The results of recent studies on the fructan metabolism of plants in winter have shown that changes in fructan contents in wintering plants that are involved in freezing tolerance and snow mold resistance might be largely controlled by regulation of the expressions of genes for fructan synthesis, whereas fructan degradation by FEHs is related to constant energy consumption for survival during winter and rapid sugar supply for regeneration or sprouting of tissues in spring.

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.

Comprehensive profiling of semi-polar phytochemicals in whole wheat grains (Triticum aestivum) using liquid chromatography coupled with electrospray ionization quadrupole time-of-flight mass spectrometry

INTRODUCTION

Wheat (Triticum aestivum) it is one of the most important staple food crops worldwide and represents an important resource for human nutrition. Besides starch, proteins and micronutrients wheat grains accumulate a highly diverse set of phytochemicals.

OBJECTIVES

This work aimed at the development and validation of an analytical workflow for comprehensive profiling of semi-polar phytochemicals in whole wheat grains.

METHOD

Reversed-phase ultra-high performance liquid chromatography coupled with electrospray ionization quadrupole time-of-flight mass spectrometry (UHPLC/ESI-QTOFMS) was used as analytical platform. For annotation of metabolites accurate mass collision-induced dissociation mass spectra were acquired and interpreted in conjunction with literature data, database queries and analyses of reference compounds.

RESULTS

Based on reversed-phase UHPLC/ESI-QTOFMS an analytical workflow for comprehensive profiling of semi-polar phytochemicals in whole wheat grains was developed. For method development the extraction procedure and the chromatographic separation were optimized. Using whole grains of eight wheat cultivars a total of 248 metabolites were annotated and characterized by chromatographic and tandem mass spectral data. Annotated metabolites comprise hydroquinones, hydroxycinnamic acid amides, flavonoids, benzoxazinoids, lignans and other phenolics as well as numerous primary metabolites such as nucleosides, amino acids and derivatives, organic acids, saccharides and B vitamin derivatives. For method validation, recovery rates and matrix effects were determined for ten exogenous model compounds. Repeatability and linearity were assessed for 39 representative endogenous metabolites. In addition, the accuracy of relative quantification was evaluated for six exogenous model compounds.

CONCLUSIONS

In conjunction with non-targeted and targeted data analysis strategies the developed analytical workflow was successfully applied to discern differences in the profiles of semi-polar phytochemicals accumulating in whole grains of eight wheat cultivars.

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.

Meeting the challenge of developing food crops with improved nutritional quality and food safety: leveraging proteomics and related omics techniques

Eliminating malnutrition remains an imminent priority in our efforts to achieve food security and providing adequate calories, proteins, and micronutrients to the growing world population. Malnutrition may be attributed to socio-economic factors (poverty and limited accessibility to nutritional food), dietary preferences, inherent nutrient profiles of traditional food crops, and to a combination of all such factors. Modern advancements in "omics" technology have made it possible to reliably predict, diagnose, and suggest ways to remedy the low protein content and bioavailability of key micronutrients in food crops. In this review, we briefly describe how proteomics techniques can potentially be used for improving the nutrient profile of major crops, through high throughput multiplexed assays. Food safety is another important issue where proteomics and related platforms can offer solution for absolute quantitation of food allergens and mycotoxins present in the plant-based food. The purpose of the present review is to discuss the proteomic-based strategies in food crops to meet the challenges of overcoming malnutrition throughout the world.

Influence of acid depolymerization parameters on levan molar mass distribution and its utilization by bacteria

Levan is a fructan composed of β -(2, 6) linkages in its main chain. Its health properties, especially its prebiotic potential can be partially modified by changing its molar mass distribution. Given that native levan is rarely fermented by probiotic bacteria, especially lactic acid bacteria (LAB), levanoligosaccharides (LOS) were produced by mild acid hydrolysis. The response surface methodology (RSM) was applied to determine the optimum parameters for depolymerization. Gel permeation chromatography (GPC) was used to characterize the LOS produced and to show the differences between inulin and levan. The prebiotic potential of four fractions of LOS with different molar mass distributions was investigated. MRS (Mann Rogosa Sharpe) medium supplemented with the LOS were inoculated with bacterial strains and growth was monitored by measuring the turbidity of the cultures. The utilization of oligofructans was also confirmed by RP-UHPLC-UV-ESI-MS (liquid chromatography coupled with mass spectrometry) measurements of LOS derivatized with 1-phenyl-3-methyl-5-pyrazolone (PMP). It was observed that the degree of polymerization of LOS has an influence on the growth of the tested bacteria.

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.

Influence of Diet on the Course of Inflammatory Bowel Disease

BACKGROUND

While the importance of diet in the pathogenesis of inflammatory bowel disease (IBD) is generally recognized, influence of food on the course of IBD is little understood.

AIM

The purpose of this study was to assess the association between food intake and course of disease in patients with IBD.

METHODS

We performed a cross-sectional study on 103 adult patients (50 with active disease and 53 in remission, divided by their calprotectin level), who completed a food frequency questionnaire on their intake of several foods over 1 year. Diet, as assessed using a 146-item self-administered food frequency questionnaire, was correlated with objective evidence of disease based on fecal calprotectin levels.

RESULTS

Legumes and potato were inversely associated with disease relapse (p value for trend 0.023) with patients in the highest quartile for legume and potato consumption carrying a 79% lower risk of active disease (adjusted OR 0.21, 95% CI 0.57-0.81). A positive association emerged between meat intake and disease relapse, the highest quartile for meat consumption coinciding with a higher risk of active disease (OR 3.61, 95% CI 1.15-11.38), though this was not significant in the adjusted analysis. No statistically significant associations were found between disease relapse and the intake of vegetables, cereals, dairy products, or fish.

CONCLUSIONS

Our results suggest a potentially protective role of legumes and potato and a detrimental influence of meat in maintaining clinical remission in IBD patients. These findings have important public health implications, but further interventional studies will be needed to demonstrate these associations.

Structural Modifications of Fructans in Aloe barbadensis Miller (Aloe Vera) Grown under Water Stress

Aloe barbadensis Miller (Aloe vera) has a Crassulaceae acid metabolism which grants the plant great tolerance to water restrictions. Carbohydrates such as acemannans and fructans are among the molecules responsible for tolerating water deficit in other plant species. Nevertheless, fructans, which are prebiotic compounds, have not been described nor studied in Aloe vera, whose leaf gel is known to possess beneficial pharmaceutical, nutritional and cosmetic properties. As Aloe vera is frequently cultivated in semi-arid conditions, like those found in northern Chile, we investigated the effect of water deficit on fructan composition and structure. For this, plants were subjected to different irrigation regimes of 100%, 75%, 50% and 25% field capacity (FC). There was a significant increase in the total sugars, soluble sugars and oligo and polyfructans in plants subjected to water deficit, compared to the control condition (100% FC) in both leaf tips and bases. The amounts of fructans were also greater in the bases compared to the leaf tips in all water treatments. Fructans also increase in degree of polymerization with increasing water deficit. Glycosidic linkage analyses by GC-MS, led to the conclusion that there are structural differences between the fructans present in the leaves of control plants with respect to plants irrigated with 50% and 25% FC. Therefore, in non-stressed plants, the inulin, neo-inulin and neo-levan type of fructans predominate, while in the most stressful conditions for the plant, Aloe vera also synthesizes fructans with a more branched structure, the neofructans. To our knowledge, the synthesis and the protective role of neo-fructans under extreme water deficit has not been previously reported.

Chemical characterization and prebiotic activity of fructo-oligosaccharides from Stevia rebaudiana (Bertoni) roots and in vitro adventitious root cultures

Stevia rebaudiana (Bertoni) is widely studied because of its foliar steviol glycosides. Fructan-type polysaccharides were recently isolated from its roots. Fructans are reserve carbohydrates that have important positive health effects and technological applications in the food industry. The objective of the present study was to isolate and characterize fructo-oligosaccharides (FOSs) from S. rebaudiana roots and in vitro adventitious root cultures and evaluate the potential prebiotic effect of these molecules. The in vitro adventitious root cultures were obtained using a roller bottle system. Chemical analyses (gas chromatography-mass spectrometry, (1)H nuclear magnetic resonance, and off-line electrospray ionization-mass spectrometry) revealed similar chemical properties of FOSs that were obtained from the different sources. The potential prebiotic effects of FOSs that were isolated from S. rebaudiana roots enhanced the growth of both bifidobacteria and lactobacilli, with strains specificity in their fermentation ability.