Nutritional and sensory challenges of gluten-free bakery products: a review

There is a growing need for gluten-free bakery products. Currently, gluten-free bakery products deliver lower protein, fibre and mineral content and elevated glycaemic index (GI) than gluten-containing foods. Only a mixture of rice and buckwheat flour or a low addition of either egg white or whey protein, has shown potential for the improvement of both nutrition and sensory qualities. To increase the fibre content, isolated cereal fibre and soluble fibre isolates have been incorporated into gluten-free formulations with some sensory success. Studies have shown that the GI of modern gluten-free products is no longer a major concern with the improvement of ingredient formulations and processing methods. The currently low mineral content can be increased with the use of mineral-rich ingredients such as amaranth, buckwheat or flaxseed flour. Nonetheless, consumers still show a preference to refined, low fibre breads over wholegrain fibre-rich bread.     

The effect of starch-protein interaction in wheat on the glycemic response and rate of in vitro digestion

To determine the effect on blood glucose of removal of protein from wheat products, healthy volunteers took test meals of white bread made from either regular or gluten-free flour. After bread made from gluten-free flour, the blood-glucose rise was significantly greater. This corresponded with a significantly more rapid rate of digestion in vitro and reduced starch malabsorption in vivo as judged by breath-H2 measurements. Addition of gluten to the gluten-free bread mix did not reverse these effects. Factors associated with unprocessed wheat flour, such as the natural starch-protein interaction, may therefore be important in wheat products in reducing both their rate of absorption and glycemic response. They may have implications in the dietary management both of diabetes and of diseases where small intestinal absorptive capacity is impaired.     

Gluten-free bread formulated with Prosopis ruscifolia (vinal) seed and corn flours

Abstract

Vinal (Prosopis ruscifolia) is a wild leguminous tree found widely in the north of Argentina. Like other Prosopis, vinal can grow under extreme temperatures, in poor soils and can tolerate high saline conditions. Taking into account the high protein and gums contents of vinal seeds, a gluten-free bread was developed including them and corn flour. A central composite design involving vinal seed flour/corn starch ratio (X1) and corn flour/corn starch ratio (X2) was used, and second-order models for specific volume (Y1) and bread score (Y2), evaluated by an expert panel, were employed to generate response surfaces. In the optimum zone of response surfaces, a product with higher protein content (5.2 g/100 g) than gluten-free breads found in local commercial markets was obtained. Also, an interesting antioxidant activity (115 mg ascorbic acid equivalent/100 g) was found in optimized gluten-free bread.     

Enrichment of gluten-free cakes with lupin (Lupinus albus L.) or buckwheat (Fagopyrum esculentum M.) flours

In the present study, the effect of debittered lupin flour (LF) and whole buckwheat flour (BF) on the nutritional and sensory quality of gluten-free cake was studied. LF (10, 20, 30 and 40%) and BF (5, 10, 15 and 20%) were partially replaced with corn starch and rice flour mixture (1:1 w/w) in the gluten-free cake recipe. LF increased the protein, calcium, iron, manganese, phosphorus and zinc contents of the cakes, while BF caused a significant increase (P < 0.05) especially in potassium and magnesium contents of the gluten-free cakes. According to the overall acceptability rating, it was concluded that gluten-free cake could be produced with satisfactory results by the addition of LF and BF up to 30% and 10%, respectively.     

Hydrocolloids in gluten-free breads: a review

Bread is a traditional food generally prepared from wheat flour. The main wheat component responsible for bread quality is gluten, which is an essential structure-binding protein. Although important, this protein can cause health problems in predisposed individuals, and is avoided in the diet of celiac disease patients. As diagnosis methods are improved, revealing the high incidence of gluten-intolerance in the western world, the demand for novel, nutritious and high-quality gluten-free foods also ascends. However, for the production of gluten-free breads the absence of gluten is critical and challenging in regards to the bread structure. Various gluten-free formulations have applied hydrocolloids to mimic the viscoelastic properties of gluten. They comprise a number of water-soluble polysaccharides with varied chemical structures providing a range of functional properties that make them suitable to this application. This paper reviews some actual facts about celiac disease and focuses on the reported applications of hydrocolloids in gluten-free breads.     

Enrichment of gluten-free cakes with lupin (Lupinus albus L.) or buckwheat (Fagopyrum esculentum M.) flours

In the present study, the effect of debittered lupin flour (LF) and whole buckwheat flour (BF) on the nutritional and sensory quality of gluten-free cake was studied. LF (10, 20, 30 and 40%) and BF (5, 10, 15 and 20%) were partially replaced with corn starch and rice flour mixture (1:1 w/w) in the gluten-free cake recipe. LF increased the protein, calcium, iron, manganese, phosphorus and zinc contents of the cakes, while BF caused a significant increase (P < 0.05) especially in potassium and magnesium contents of the gluten-free cakes. According to the overall acceptability rating, it was concluded that gluten-free cake could be produced with satisfactory results by the addition of LF and BF up to 30% and 10%, respectively.     

Occupational buckwheat allergy as a cause of allergic rhinitis,asthma, contact urticaria and anaphylaxis—An emerging problem in food-handling occupations?

Buckwheat is a known, though uncommon, allergen in occupational settings. It has recently gained popularity as healthy food and as an ingredient in gluten-free diets. We describe a series of six patient cases with occupational immediate allergy to buckwheat. Three cooks, two bakers, and a worker in a grocery store were occupationally exposed to buckwheat flour and developed immediate allergy to buckwheat, which was confirmed by skin prick testing and measurement of specific immunoglobulin E antibodies. Four of the patients were diagnosed with occupational asthma, four with occupational rhinitis, and two with occupational contact urticaria caused by buckwheat. Three of the six patients suffered anaphylaxis as consequence of their occupational buckwheat allergy after ingestion of food that contained buckwheat. The high rate of life-threatening reactions, together with a short exposure time to buckwheat before sensitization occurred in these cases, highlights the importance of a detailed occupational history and a high index of suspicion for occupational food allergens.     

Analysis of ingredient and nutritional labeling of commercially available gluten-free bread in Brazil

This study aimed at evaluating the ingredients and nutritional information of commercially-available gluten-free bread (GFB) in Brazil. A total of 128 products were studied, of which 87% presented the sandwich loaf shape. Traditional GFBs (n?=?114) had as main ingredient the refined rice flour and starches, whereas alternative ones (n?=?14) presented whole rice flour. Raw materials suggested by science to improve nutrients and bioactive compounds of gluten-free foodstuffs were observed in the ingredient list of most products (n?=?86); however, they were used in lower levels, thus no significant differences were observed for nutritional information between the different categories of GFB. No products with added vitamins or minerals were found, though 77% of them included hydrocolloids in their formulations – other food additives were also observed. Despite the increased gluten-free food market, there is still a gap between science and market, especially regarding the approaches to improve the GFB diversity and nutritional quality.     

Oral Consumption of Bread from an RNAi Wheat Line with Strongly Silenced Gliadins Elicits No Immunogenic Response in a Pilot Study with Celiac Disease Patients

Celiac disease (CD) is a genetically predisposed, T cell-mediated and autoimmune-like disorder caused by dietary exposure to the storage proteins of wheat and related cereals. A gluten-free diet (GFD) is the only treatment available for CD. The celiac immune response mediated by CD4+ T-cells can be assessed with a short-term oral gluten challenge. This study aimed to determine whether the consumption of bread made using flour from a low-gluten RNAi wheat line (named E82) can activate the immune response in DQ2.5-positive patients with CD after a blind crossover challenge. The experimental protocol included assessing IFN-γ production by peripheral blood mononuclear cells (PBMCs), evaluating gastrointestinal symptoms, and measuring gluten immunogenic peptides (GIP) in stool samples. The response of PBMCs was not significant to gliadin and the 33-mer peptide after E82 bread consumption. In contrast, PBMCs reacted significantly to Standard bread. This lack of immune response is correlated with the fact that, after E82 bread consumption, stool samples from patients with CD showed very low levels of GIP, and the symptoms were comparable to those of the GFD. This pilot study provides evidence that bread from RNAi E82 flour does not elicit an immune response after a short-term oral challenge and could help manage GFD in patients with CD.     

Two patients with occupational asthma who returned to work with dust respirators

OBJECTIVES—To assess the efficacy of dust respirators in preventing asthma attacks in patients with occupational asthma (asthma induced by buckwheat flour or wheat flour).
METHODS—The effect of the work environment was examined in two patients with occupational asthma with and without the use of a commercially available mask or a dust respirator. Pulmonary function tests were performed immediately before and after work and at 1 hourly intervals for 14 hours after returning to the hospital.
RESULTS—In patient 1, environmental exposure resulted in no symptoms during and immediately after work, but coughing, wheezing, and dyspnoea developed after 6 hours. Peak expiratory flow rate (PEFR) decreased by 44% 7 hours after leaving the work environment, showing only a positive late asthmatic reaction (LAR). In patient 2, environmental exposure resulted in coughing and wheezing 10 minutes after initiation during bread making, and PEFR decreased by 39%. After 7 hours, PEFR decreased by 34%. The environmental provocation tests in both patients were repeated after wearing a commercial respirator. This resulted in a complete suppression of LAR in patient 1 and of immediate asthmatic reaction (IAR) and LAR in patient 2.
CONCLUSIONS—Two patients with asthma induced by buckwheat flour or wheat flour in whom asthmatic attacks could be prevented with a dust respirator are reported. Dust respirators are effective in preventing asthma attacks induced by buckwheat flour and wheat flour.


Keywords: asthma: buckwheat flour: wheat flour; environmental provocation test     

The glycaemic and C-peptide responses of foods rich in dietary fibre from oat,buckwheat and lingonberry

Dietary fibre has a beneficial effect on metabolic syndrome, e.g. by influencing the absorption of glucose. The source and structure of fibre affect the glucose response. In this study, the glycaemic and insulinaemic response to oat bread, oat bread with lingonberry fibre, oat–buckwheat bread and buckwheat porridge were tested in a small-scale clinical study (KHSHP E514/09). Nine healthy volunteers consumed test foods after overnight fasting. Serum glucose and C-peptide levels were determined by colorimetric and ELISA methods, respectively, from samples taken at seven time points during 120 min. The mean glycaemic and C-peptide indexes (C-pepIs) were 32 and 100 for oat bread, 47 and 119 for oat–lingonberry fibre bread, 58 and 105 for oat–buckwheat bread and 71 and 77 for buckwheat porridge. Similar to rye, buckwheat porridge having a relatively high glycaemic index (GI) tended to have a low C-pepI. Buckwheat and lingonberry fibres provide new alternatives for low GI foods.     

Potential use of cyclodextrin-glycosyltransferase enzyme in bread-making and the development of gluten-free breads with pinion and corn flours

Abstract

Gluten-free breads are an alternative for celiacs but are characterized by deficient sensory qualities compared with traditional breads. This work aimed to incorporate a commercial CGTase enzyme and the CGTase produced by Bacillus firmus strain 37 in the production of these breads to overcome these drawbacks. The flours employed were corn and pinion flours, which had the best CD production by CGTase, and exhibited good antioxidant activity, respectively. Rice flour was used as a control. The addition of the CGTase enzyme increased the specific volume and improved the texture of the breads. In the sensory analyses, the best score given by non-celiacs was for bread with pinion and rice flours and CGTase from B. firmus strain 37, while celiacs awarded the best score to the bread with rice flour only and same enzyme. The results demonstrate an improvement in the sensory and technological characteristics of gluten-free breads using the CGTase enzyme.     

Effect of hydrocolloids on selected properties of gluten-free dough and bread

Addition of hydrocolloids (H/C) in gluten-free (GF) bread formulation is necessary in order to act as polymeric substances that should mimic the viscoelastic properties of gluten and increase the dough's gas-retaining ability. The properties of H/C vary depending on their origin and chemical structure. Addition of H/C (hydroxypropylmethylcellulose (HPMC), xanthan, κ-carrageenan and guar gum) of different origins at 1%, 1.5% and 2% (w/w) in GF formulations based on corn starch and rice flour was carried out to investigate the effects on dough rheology and bread quality. The consistency, viscosity and thermal properties of doughs were evaluated. According to results, 1% and 1.5% addition of H/C (except from xanthan) contributed to bread with higher loaf volume and better color compared to control GF bread as well as to increased shelf life due to its moisture-absorption ability. Sensory evaluation by a trained panel revealed a preference for bread containing 1.5% HPMC because of its loaf volume, appearance and firmness characteristics. The micrographs of the dough showed a continuous matrix between starch and HPMC obtaining a more aerated structure.     

Estimated Levels of Gluten Incidentally Present in a Canadian Gluten-Free Diet

Avoiding exposure to gluten is currently the only effective treatment for celiac disease. However, the evidence suggests that for most affected individuals, exposure to less than 10 mg/day is unlikely to cause histological changes to the intestinal mucosa. The daily diet of people with celiac disease does not rely solely on gluten-free pre-packaged foods, but also on naturally gluten-free grains (e.g., rice, buckwheat, ...) and foods with grain-derived ingredients (i.e., flour and starches) used for cooking and baking at home. The objective of this study was to estimate the level of incidental gluten potentially present in gluten-free diets from a Canadian perspective. We have conducted gluten exposure estimations from grain-containing foods and foods with grain-derived ingredients, taking into consideration the various rates of food consumption by different sex and age groups. These estimates have concluded that if gluten was present at levels not exceeding 20 ppm, exposure to gluten would remain below 10 mg per day for all age groups studied. However, in reality the level of gluten found in naturally gluten-free ingredients is not static and there may be some concerns related to the flours made from naturally gluten-free cereal grains. It was found that those containing a higher level of fiber and that are frequently used to prepare daily foods by individuals with celiac disease could be a concern. For this category of products, only the flours and starches labelled “gluten-free” should be used for home-made preparations.     

Using white sorghum flour for gluten-free breadmaking

Cornstarch/sorghum flour (X?) ratio, water added (X?) and amount of hydroxypropyl methylcellulose (HPMC) used (X?) were varied for making gluten-free bread so as to optimize batter softness (Y?), specific volume (Y?) and crumb grain (Y?). A second-order model was employed to generate a response surface. It was found that the softness of the batter depends significantly on three factors in a linear way. The specific volume (Y?), in particular, was increased significantly with the increment of X? and X?. The crumb grain (Y?) depended significantly on three factors, its scores increased with X? and decreased with the water added (X?). Finally, 0.55 cornstarch/sorghum flour ratio, 90% of water added and 3% of HPMC were chosen as the best conditions, considering acceptable levels of specific volume and of crumb grain, and also taking into account the possibility of using the highest proportion of sorghum flour.     

Development and Acceptability of Gluten-Free Madeleine

The objective of this study was to develop gluten-free madeleine with classic organoleptic features as well as nutritional and sensory quality. In its formulation, the madeleine wheat flour was replaced by almond flour, rice flour, and xanthan gum. Proper ingredient and preparation technique choices has enabled the improvement of a product with acceptability rates over 90% among celiac and non-celiac tasters. In addition, it has lower calorie and lipid values as well as larger fiber content, significantly improving the nutritional product value when compared to those available in the market.     

Green banana pasta: an alternative for gluten-free diets

The objective of this study was to develop and analyze a gluten-free pasta made with green banana flour. The study was divided into five steps: preparation/selection, chemical, sensory, technological, and statistical analysis. The modified sample presented greater acceptance (84.5% for celiac individuals and 61.2% for nonceliac) than standard samples (53.6% for nonceliac individuals). There was no significant difference between the modified and the standard samples in terms of appearance, aroma, flavor, and overall quality. The modified pastas presented approximately 98% less lipids. Green bananas are considered a subproduct of low commercial value with little industrial use. The possibility of developing gluten-free products with green banana flour can expand the product supply for people with celiac disease and contribute to a more diverse diet.     

Physico-chemical and sensory characteristics of gluten-free breads made with pine nuts (Araucaria angustifolia) associated to other flours

Pine nuts are the seeds of Araucaria angustifolia, which have a good nutritional value and relevance to be investigated in food technology, especially in bakery products for celiac people. This study aimed to evaluate physico-chemical and sensory properties of gluten-free breads made with pine nuts. Four different formulations (T1, T2,T3, and T4) of bread were prepared, varying the percentages flours, and were submitted to physical, chemical, and sensory analysis. The formulation made with pine nut and potato starch and the one made with pine nuts associated with potato starch and rice flour are promising alternatives for celiac patients.     

Cereal-Based Gluten-Free Food: How to Reconcile Nutritional and Technological Properties of Wheat Proteins with Safety for Celiac Disease Patients

The gluten-free diet is, to date, the only efficacious treatment for patients with Celiac Disease. In recent years, the impressive rise of Celiac Disease incidence, dramatically prompted changes in the dietary habit of an increasingly large population, with a rise in demand of gluten-free products. The formulation of gluten-free bakery products presents a formidable challenge to cereal technologists. As wheat gluten contributes to the formation of a strong protein network, that confers visco-elasticity to the dough and allows the wheat flour to be processed into a wide range of products, the preparation of cereal-based gluten-free products is a somehow difficult process. This review focuses on nutritional and technological quality of products made with gluten-free cereals available on the market. The possibility of using flour from naturally low toxic ancient wheat species or detoxified wheat for the diet of celiacs is also discussed.     

Making bread with sourdough improves mineral bioavailability from reconstituted whole wheat flour in rats

OBJECTIVE: We compared the effects of different kinds of bread fermentation on mineral bioavailability. METHODS: Wistar rats were fed one of the following experimental diets for 21 d: control, reconstituted whole wheat flour (white flour plus bran), yeast bread, and sourdough bread. The apparent mineral absorption and intestinal fermentation were measured in each animal. RESULTS: Phytate contents in yeast and sourdough bread were lower than in reconstituted whole wheat flour (-52% and -71%, respectively). Total cecal pool of short-chain fatty acids, in particular the butyrate pool, was significantly increased by the ingestion of unrefined products. Calcium homeostasis was not modified by these nutritional conditions, whereas magnesium absorption was significantly greater in rats fed the control and sourdough diets than in those consuming whole wheat flour and yeast bread. Magnesium kidney excretion was slightly stimulated by sourdough bread. Compared with the control diet, iron balance was significantly reduced by reconstituted whole wheat flour diet. Yeast bread making counteracted the deleterious effects of whole wheat on iron absorption, whereas sourdough bread making enhanced iron absorption. Further, liver and plasma iron and transferrin saturation levels were lower in rats adapted to the flour diet than in other groups. Zinc absorption was strongly depressed in the presence of unprocessed reconstituted whole wheat flour in the diet, but yeast fermentation afforded a zinc assimilation comparable to the control diet, whereas the sourdough bread led to maximal zinc absorption. Copper absorption increased significantly when rats were fed the sourdough bread, whereas unprocessed whole flour depressed copper absorption (-41% versus control diet). CONCLUSION: Mineral bioavailability from reconstituted whole wheat flour can be improved by bread making. Although yeast fermentation minimizes the unfavorable effects of phytic acid, sourdough bread is a better source of available minerals, especially magnesium, iron, and zinc.