Effects of barley β-glucan-enriched flour fractions on the glycaemic index of bread

QTL Analysis of β-Glucan Content and Other Grain Traits in a Recombinant Population of Spring Barley

Barley with high grain β-glucan content is valuable for functional foods. The identification of loci for high β-glucan content is, thus, of great importance for barley breeding. Segregation mapping for the content in β-glucan and other barley grain components (starch, protein, lipid, ash, phosphorous, calcium, sodium) was performed using the progeny of the cross between Glacier AC38, a mutant with high amylose, and CDC Fibar, a high β-glucan waxy cultivar. The offspring of this cross showed transgressive segregation for β-glucan content. Linkage analysis based on single-nucleotide polymorphism (SNP) molecular markers was used for the genotyping of the parents and recombinant inbred lines (RILs). Two Quantitative Trait Loci (QTL) for β-glucan content and several QTL for other grain components were found. The former ones, located on chromosomes 1H and 7H, explained 27.9% and 27.4% of the phenotypic variance, respectively. Glacier AC38 provided the allele for high β-glucan content at the QTL on chromosome 1H, whereas CDC Fibar contributed the allele at the QTL on chromosome 7H. Their recombination resulted in a novel haplotype with higher β-glucan content, up to 18.4%. Candidate genes are proposed for these two QTL: HvCslF9, involved in β-glucan biosynthesis, for the QTL on chromosome 1H; Horvu_PLANET_7H01G069300, a gene encoding an ATP-Binding Cassette (ABC) transporter, for the QTL on chromosome 7H.

Durum Wheat Bread with a Potentially High Health Value through the Addition of Durum Wheat Thin Bran or Barley Flour

The enrichment of semolina bread with prebiotic ingredients such as β-glucans may exert health-promoting effects. This work presents the results of a general recipe development aimed at improving the nutritional value of bakery products. In this study, increasing amounts (0%, 2%, 5%, 7%, and 10%) of thin bran or barley flour were added into re-milled durum wheat semolina to prepare breads. The technological quality of doughs and breads was investigated. In general, the Farinograph water absorption of flour and dough stability increased with increasing inclusion levels of barley flour or thin bran (up to 73.23% and 18.75 min, respectively), contrarily to the increase of dough development time only in barley inclusion (4.55 min). At the same time, the softening index decreased for almost all of these, except for 2% of thin bran or barley flour inclusion. At Mixograph, mixing time increased (up to 5.13 min) whilst the peak height decreased. The specific volume and hardness of loaf differently decreased for almost all thesis (ranges 12.6-24.0% and 39.4-45.5%, respectively). The other quality parameters remained unchanged compared with semolina bread. After baking, β-glucan levels increased differently at all the inclusion levels (2.35-fold, on average). The breadcrumb color was deep brown, while the crust became lighter in color. The breads contain β-glucans even at low percentages of barley/bran inclusions while maintaining their technological performance. In conclusion, the results show an interesting potential of barley flour or thin bran as ingredients in breadmaking to increase the β-glucans daily intake, but further investigations are needed to achieve improved quality features.

Effects of whole-grain barley and oat β-glucans on postprandial glycemia and appetite: a randomized controlled crossover trial

This study aimed to determine the postprandial effects of barley bread (BB) and oat bread (OB), grain sources of β-glucans, on glycaemia and appetite by comparison with white bread (WB) and whole-wheat bread (WWB). This randomized controlled crossover trial included 20 healthy individuals (10 males and 10 females) who consumed WB, WWB, BB, and OB with a standard breakfast followed by an ad libitum lunch. Postprandial glucose and appetite responses were quantified as the incremental area under the curve (iAUC). Although the iAUC for glycaemic response was lower by 23.7%, 29.9%, and 27.9% after the consumption of BB, OB, and WWB compared with WB (p = 0.023), no differences were observed between BB, OB, and WWB (p > 0.05). BB had a lower iAUC for appetite sensation by 21.5%, 23.9%, and 55.7% compared with WB, WWB, and OB (p = 0.005). OB had no effect on appetite and was also less palatable than BB. Subsequent food intakes were similar after the consumption of all test breads (p > 0.05). The encouragement of healthier bread formulations that can beneficially modulate postprandial glycemia and appetite may contribute to the promotion of public health. This trial was registered at ClinicalTrials.gov as NCT04749498.

Indirect Measurement of β-Glucan Content in Barley Grain with Near-Infrared Reflectance Spectroscopy

β-Glucan is a component of barley grains with functional properties that make it useful for human consumption. Cultivars with high grain β-glucan are required for industrial processing. Breeding for barley genotypes with higher β-glucan content requires a high-throughput method to assess β-glucan quickly and cheaply. Wet-chemistry laboratory procedures are low-throughput and expensive, but indirect measurement methods such as near-infrared reflectance spectroscopy (NIRS) match the breeding requirements (once the NIR spectrometer is available). A predictive model for the indirect measurement of β-glucan content in ground barley grains with NIRS was therefore developed using 248 samples with a wide range of β-glucan contents (3.4%–17.6%). To develop such calibration, 198 unique samples were used for training and 50 for validation. The predictive model had R² = 0.990, bias = 0.013% and RMSEP = 0.327% for validation. NIRS was confirmed to be a very useful technique for indirect measurement of β-glucan content and evaluation of high-β-glucan barleys.

Dietary fiber in bakery products: Source, processing, and function

Bakery products are prevalently consumed foods in the world, and they have been regarded as convenient dietary vehicles for delivering nutritive ingredients into people's diet, of which, dietary fiber (DF) is one of the most popular items. The food industry attempts to produce fiber-enriched bakery products with both increasing nutritional value and appealing palatability. As many new sources of DFs become available, and consumers are moving towards healthier diets, studies of using these DFs as functional ingredients in baked goods are becoming vast. Besides, the nutrition value of DF is commonly accepted, and many investigations have also revealed the health benefits of fiber-enriched bakery products. Thus, this chapter presents an overview of (1) trends in supplementation of DF from various sources, (2) impact of DF on dough processing, quality and physiological functionality of bakery products, and (3) technologies used to improve the compatibility of DF in bakery products.

The contribution of gastric digestion of starch to the glycaemic index of breads with different composition or structure

Breads of higher density exhibit lower glycaemic index (GI) both in vivo and in vitro, a phenomenon generally attributed to a slower intestinal starch digestion. The aim of this work was to gain a better understanding of the relationship between bread density, oral and gastric digestion, and GI. Three breads were studied: industrial-style and traditional-style French baguettes (similar composition, different densities), and whole-wheat baguette. In vitro GI predictions confirmed that, for an identical composition, higher bread density was associated with a lower GI. Subsequent oro-gastric digestions, using the dynamic system DIDGI®, showed extensive starch digestion at the gastric stage by salivary α-amylase, in line with recently published data. They further showed that higher bread density led to a lower hydrolysis rate. The concurrence of these results with those of in vivo studies, suggests a mediating role for gastric digestion in the relationship between bread density and GI, possibly via the repercussions on the starch proportion that remains to be hydrolysed in the small intestine. This study therefore adds to the scientific knowledge of the importance of salivary α-amylase to starch digestion, and draws special attention to the possible role of the gastric phase in determining the GI.

Molecular Characteristics, Synthase, and Food Application of Cereal β-Glucan

Cereal β-glucan is a type of valuable dietary fiber that mainly exists in the aleurone, subaleurone, and endosperm of some cereal grains. β-Glucan is acknowledged as a functional food ingredient owing to its multiple health benefits, including the prevention of diabetes, reduction in the incidence of cardiovascular disease, antitumor effects, antioxidant activities, and immunostimulation. It is well documented that cellulose synthase-like CslF/H/J genes encode synthases responsible for β-glucan biosynthesis in cereal grains. Recently, β-glucan has been widely applied as an emulsion stabilizer, thickening agent, fat substitute, and bioactive ingredient in the food industry due to its water solubility, viscosity, gelation property, and health benefits. Therefore, the present paper aims to review the molecular characteristics, synthase gene family, and food application of cereal β-glucan in recent years.

Effects of the addition of waxy and normal hull-less barley flours on the farinograph and pasting properties of composite flours and on the nutritional value, textural qualities, and in vitro digestibility of resultant breads

Hull-less barley (HLB), especially waxy HLB, contains many physiologically active ingredients; however, its poor processing performance and end-product quality are unfavorable. In this study, 80% waxy or normal HLB wholegrain flour (WGF) and 20% wheat flour were used for baking bread. The farinograph and pasting properties of composite powders, and the nutritional value, textural properties, and in vitro hydrolysis of resultant breads were evaluated. The addition of a high proportion of HLB WGFs significantly increased the nutritional value of breads, especially the β-glucan contents of waxy HLB breads. The addition of HLB WGFs and a suitable amount of wheat gluten led to a lower degree of softening of HLB bread flours but improved its farinograph characteristics, such as higher water absorption rate, development time, stability time, and farinograph quality number. Although the sensory profiles of HLB breads were considerably lower than those of wheat bread, they still received a good overall acceptability from a panel of sensory evaluators. HLB breads, particularly the waxy types, exhibited higher hardness, gumminess, chewiness, and lower specific volume, glycemic index and equilibrium concentration in starch hydrolysis. After baking, the starch crystallinity of dough changed from A to V type, and the relative crystallinity decreased. Overall, waxy HLB breads had more nutritional value than normal HLB breads. Higher β-glucan and total dietary fiber content in HLB might have a positive effect on the nutritional value of the resultant breads. However, high β-glucan and total dietary fiber was also accompanied by a negative effect on the sensory quality and processing performance of the end product. PRACTICAL APPLICATION: The composite flour with 80 g hull-less barley wholegrain flour, 20 g wheat flour, and 30 g wheat gluten can be substituted in breadmaking. Compared to wheat bread, hull-less barley bread exhibited different but acceptable sensory properties and had more nutritional value, particularly the waxy one. Therefore, a high proportion of hull-less barley could be recommended for bread production.

Enrichment of bread with beta-glucans or resistant starch induces similar glucose, insulin and appetite hormone responses in healthy adults

PURPOSE

β-Glucans (βG) and resistant starch (RS) are known for their effects on the improvement of glucose tolerance and enhancement of insulin sensitivity. Enrichment of bread with βG or RS was performed to examine potential postprandial benefits regarding gastrointestinal hormone responses.

METHODS

Ten healthy normoglycaemic adults participated in the study and were provided with either a glucose solution (reference food, GS) or bread enriched with β-glucans (βGB) (3.6 g/30 g available CHO) or bread enriched with resistant starch (RSB) (15% of total starch), with 1-week intervals in amounts that yielded 50 g of available carbohydrates. Venous blood samples were collected before consumption and at 15, 30, 45, 60, 90, 120 and 180 min postprandially. Glucose, insulin, ghrelin, glucagon-like peptide-1 (GLP-1) and peptide YY (PYY) responses as well as glycaemic index (GI) and subjective appetite ratings were evaluated.

RESULTS

Ingestion of βGB and RSB elicited lower incremental area under the curve (iAUC) for glycaemic response compared to GS (P < 0.05). Both breads demonstrated a low GI (βGB: 48, RSB: 40). There were no significant differences in insulin response, ghrelin, GLP-1 or PYY between the two breads. A significantly lower desire to eat and higher fullness were detected 15 min after βGB and RSB consumption and until 180 min (P < 0.05 compared to GS).

CONCLUSION

Enrichment of bread with either βG or RS produced a low GI product but the two breads were not significantly different in relation to insulin, ghrelin, GLP-1 and PYY responses. The development of bread products which cause improved metabolic effects is of great importance for the promotion of public health.

Molecular Mechanism of Functional Ingredients in Barley to Combat Human Chronic Diseases

Barley plays an important role in health and civilization of human migration from Africa to Asia, later to Eurasia. We demonstrated the systematic mechanism of functional ingredients in barley to combat chronic diseases, based on PubMed, CNKI, and ISI Web of Science databases from 2004 to 2020. Barley and its extracts are rich in 30 ingredients to combat more than 20 chronic diseases, which include the 14 similar and 9 different chronic diseases between grains and grass, due to the major molecular mechanism of six functional ingredients of barley grass (GABA, flavonoids, SOD, K-Ca, vitamins, and tryptophan) and grains (β-glucans, polyphenols, arabinoxylan, phytosterols, tocols, and resistant starch). The antioxidant activity of barley grass and grain has the same and different functional components. These results support findings that barley grain and its grass are the best functional food, promoting ancient Babylonian and Egyptian civilizations, and further show the depending functional ingredients for diet from Pliocene hominids in Africa and Neanderthals in Europe to modern humans in the world. This review paper not only reveals the formation and action mechanism of barley diet overcoming human chronic diseases, but also provides scientific basis for the development of health products and drugs for the prevention and treatment of human chronic diseases.

Application of rich in β-glucan flours and preparations in bread baked from frozen dough

This study aims to define the changes in the quality of bakery products depending on the β-glucan source and its contribution using bake-off technology. The examined bread was enriched with a 10% addition of oat flour, barley flour, oat fibre preparation, and barley fibre preparation. Bread was tested for rheological parameters, baking performance, hardness and springiness, water content, specific volume, porosity, crust and crumb colour, and β-glucan content. In the executed research, the adverse effect of this component on the formation of gluten network and hardness of the crumb was observed. In the double compression test, it was shown that the highest hardness on the day of baking was characterized by the bread with the addition of barley preparation. The fastest rate of staling was observed in the bread with additional barley flour that was affected by the highest amount of β-glucan. A significant decrease of the β-glucan level was also found during the technological bake-off process, which can be explained by the activity of enzymes.

Influence of Yeast β-Glucan on Cookies Sensory Characteristics and Bioactivities

β-Glucan is biologically active polysaccharide, ubiquitously found in many grains, bacteria, and fungi and much yeast. The aim of this study was to determine the effect of substituting wheat flour by 1, 2, and 4% yeast isolated β-glucan in cookies on the sensory acceptance, antioxidants, oxidative stability, and quality evaluation which were investigated. According to the results, cookies supplemented at 2% yeast β-glucan were proved satisfactory on sensory quality perspective. During the storage study it was found that cookies made with 2 and 4% β-glucan have effectively (p>0.05) kept the peroxide value (PV) within acceptable range, demonstrating the promising role of β-glucan in deterring oxidative. It is further noted that 2 or 4% β-glucan incorporated cookies assimilated highest absorption spectra, suggesting the retardation in freshness losses, with having minimum microbial loads, showing microbiological safety. β-Glucan fortification in foods is technologically and economically feasible, suggesting that a significant prospect of β-glucan as low-cost food ingredient in formulating cookies at 2% offers exciting new use of β-glucan of yeast origin.

Glycaemic index and load values tested in normoglycemic adults for five staple foodstuffs: pounded yam, pounded cassava-plantain, placali, attieke and maize meal stiff porridge

There is currently an increased global interest in the published glycaemic index (GI) and glycaemic load (GL) values of foods. However, data on the GI and GL values of different varieties of foods within Côte d'Ivoire are very limited. The study therefore aimed at finding the GI and GL of the main food staples in Côte d'Ivoire. Following the International Standard Organisation's protocol (ISO/FDI 26642:2010), a selection of five staple foodstuffs were tested for their GI and GL. Fasted healthy subjects were given 50 g of available carbohydrate servings of a glucose reference, which was tested twice, and test foods which were tested once, on separate occasions. Excepted attieke (GI 63), the majority of foods tested have a high GI (GI>70). Attieke (agbodjama) had a high GL (GL 29) while placali (GL 17) and maize meal stiff porridge (GL 16) had medium GLs. The GLs of pounded cassava-plantain and pounded yam are 26 and 22. Consumption of attieke could minimize postprandial blood glucose spikes, in spite of high GL and potentially have benefit in the management and prevention of some chronic diseases.

A shift toward a new holistic paradigm will help to preserve and better process grain products’ food structure for improving their health effects

A holistic approach to grain products will help preserve their food structure and nutrient density and thus their health potential.

Wholegrain barley β-glucan fermentation does not improve glucose tolerance in rats fed a high-fat diet

Fermentation of oat and barley β-glucans is believed to mediate in part their metabolic health benefits, but the exact mechanisms remain unclear. In this study, we sought to test the hypothesis that barley β-glucan fermentation raises circulating incretin hormone levels and improves glucose control, independent of other grain components. Male Sprague-Dawley rats (n = 30) were fed a high-fat diet for 6 weeks and then randomly allocated to 1 of 3 dietary treatments for 2 weeks. The low- (LBG, 0% β-glucan) and high- (HBG, 3% β-glucan) β-glucan diets contained 25% wholegrain barley and similar levels of insoluble dietary fiber, available carbohydrate, and energy. A low-fiber diet (basal) was included for comparison. Immediately prior to the dietary intervention, gastric emptying rate (using the (13)C-octanoic breath test) and postprandial glycemic response of each diet were determined. At the end of the study, circulating gut hormone levels were determined; and a glucose tolerance test was performed. The rats were then killed, and indices of cecal fermentation were assessed. Diet did not affect live weight; however, the HBG diet, compared to basal and LBG, reduced food intake, tended to slow gastric emptying, increased cecal digesta mass and individual and total short-chain fatty acid pools, and lowered digesta pH. In contrast, circulating levels of glucose, insulin, gastric-inhibitory peptide, and glucagon-like peptide-1, and glucose tolerance were unaffected by diet. In conclusion, wholegrain barley β-glucan suppressed feed intake and increased cecal fermentation but did not improve postprandial glucose control or insulin sensitivity.

Quantification of amylose, amylopectin, and β-glucan in search for genes controlling the three major quality traits in barley by genome-wide association studies

Genome-wide association studies (GWAS) for amylose, amylopectin and β-glucan concentration in a collection of 254 European spring barley varieties allowed to identify 20, 17, and 21 single nucleotide polymorphic (SNP) markers, respectively, associated with these important grain quality traits. Negative correlations between the content of amylose and β-glucan (R = -0.62, P < 0.01) and amylopectin and β-glucan (R = -0.487, P < 0.01) were found in this large collection of spring barley varieties. Besides HvCslF6, amo1 and AGPL2, sex6, and waxy were identified among the major genes responsible for β-glucan, amylose and amylopectin content, respectively. Several minor genes like HvGSL4, HvGSL3, and HvCesA6, PWD were also detected by GWAS for the first time. Furthermore, the gene encoding β-fructofuranosidase, located on the short arm of chromosome 7H at 1.49 cM, and SRF6, encoding "leucine-rich repeat receptor kinase protein" on chromosome 2 H, are proposed to be new candidate genes for amylopectin formation in barley endosperm. Several of the associated SNPs on chromosome 1, 5, 6, and 7H mapped to overlapping regions containing QTLs and genes controlling the three grain constituents. In particular chromosomes 5 and 7H carry many QTLs controlling barley grain quality. Amylose, amylopectin and β-glucan were interacted among each other through a metabolic network connected by UDP showing pleiotropic effects. Taken together, these results showed that cereal quality traits related each other and regulated through an interaction network, the identified major genes and genetic regions for amylose, amylopectin and β-glucan is a helpful for further research on carbohydrates and barley breeding.

Review of human studies investigating the post-prandial blood-glucose lowering ability of oat and barley food products

Oat and barley foods have been shown to reduce human glycaemic response, compared to similar wheat foods or a glucose control. The strength of the evidence supporting the hypothesis that the soluble fibre, mixed linkage β-glucan, reduces glycaemic response was evaluated. A search of the literature was conducted to find clinical trials with acute glycaemic response as an end point using oat or barley products. Of the 76 human studies identified, 34 met the inclusion and exclusion criteria. Dose response and ratio of β-glucan to available carbohydrate as predictors of glycaemic response were assessed. Meals provided 0.3-12.1 g oat or barley β-glucan, and reduced glycaemic response by an average of 48 ± 33 mmol · min/l compared to a suitable control. Regression analysis on 119 treatments indicated that change in glycaemic response (expressed as incremental area under the post-prandial blood-glucose curve) was greater for intact grains than for processed foods. For processed foods, glycaemic response was more strongly related to the β-glucan dose alone (r(2)=0.48, P<0.0001) than to the ratio of β-glucan to the available carbohydrate (r(2)=0.25, P<0.0001). For processed foods containing 4 g of β-glucan, the linear model predicted a decrease in glycaemic response of 27 ± 3 mmol · min/l, and 76% of treatments significantly reduced glycaemic response. Thus, intact grains as well as a variety of processed oat and barley foods containing at least 4 g of β-glucan and 30-80 g available carbohydrate can significantly reduce post-prandial blood glucose.

The effect of dietary fibre on reducing the glycaemic index of bread

As bread is the most relevant source of available carbohydrates in the diet and as lowering dietary glycaemic index (GI) is considered favourable to health, many studies have been carried out in order to decrease the GI of bread. The most relevant strategy that has been applied so far is the addition of fibre-rich flours or pure dietary fibre. However, the effectiveness of dietary fibre in bread in reducing the GI is controversial. The purpose of the present review was to discuss critically the effects obtained by adding different kinds of fibre to bread in order to modulate its glycaemic response. The studies were selected because they analysed in vivo whether or not dietary fibre, naturally present or added during bread making, could improve the glucose response. The reviewed literature suggests that the presence of intact structures not accessible to human amylases, as well as a reduced pH that may delay gastric emptying or create a barrier to starch digestion, seems to be more effective than dietary fibre per se in improving glucose metabolism, irrespective of the type of cereal. Moreover, the incorporation of technologically extracted cereal fibre fractions, the addition of fractions from legumes or of specifically developed viscous or non-viscous fibres also constitute effective strategies. However, when fibres or wholemeal is included in bread making to affect the glycaemic response, the manufacturing protocol needs to reconsider several technological parameters in order to obtain high-quality and consumer-acceptable breads.

Food-based ingredients to modulate blood glucose

Maintenance of normal blood glucose levels is important for avoiding chronic diseases such as type 2 diabetes, cardiovascular problems, and obesity. Type 2 diabetes is one of the major health problems affecting the world population and this condition can be exacerbated by poor diet, low physical activity, and genetic abnormalities. Food plays an important role in the management of blood glucose and associated complications in diabetes. This is attributed to the ability of food-based ingredients to modulate blood glucose without causing any adverse health consequences. This chapter focuses on four important food groups such as cereals, legumes, fruits, and spices that have active ingredients such as soluble dietary fiber, polyphenols, and antinutrients with the ability to reduce glycemic and insulin response in humans. Other food ingredients such as simple sugars, sugar alcohols, and some proteins are also discussed in moderation.

Genome-wide association study of resistant starch (RS) phenotypes in a barley variety collection

Barley is primarily grown for feed and malt, but in some regions of the world it is also considered to be a staple food. Some barley types such as high-amylose barley have also gained importance as health-promoting foods. Starch that is not readily digested in the upper mammalian gastrointestinal system, or resistant starch (RS), is considered to be valuable because it prevents some diet-related diseases such as colon cancer. RS was quantified in a diverse collection of 209 spring barley varieties released in Europe during the past 100 years. The RS content varied from <1% to >15% in the collection, with 13 varieties having high RS content (>11%) and 15 varieties below 1%. Combined with genome-wide association scanning (GWAS), SNP markers and candidate genes controlling the RS content in grains were identified. This identified 40 SNP markers with a LOD score above 2, located on chromosomes 2H, 3H, 5H, and 6H, respectively. Among these SNPs, 10 genes with a known role in starch biosynthesis were associated on the basis of synteny conservation to the rice genome. The β-glucan content was quantified in 61 varieties selected to represent extreme as well as medium RS values. The β-glucan amount in the 15 varieties with RS <1% ranged from 1.7 to 3.2%, ranged from 1.76 to 2.54% in the 13 varieties with RS >11%, and ranged from 1.95 to 2.82% for those with 1%< RS < 11%. No statistically significant correlation between RS content and β-glucan content was found. This association analysis of commercial varieties revealed a large variation in RS content and identified a number of SNP markers that can be explored for selection and further dissection of the pathway and control of RS phenotype.