Plant-Based Antioxidants in Gluten-Free Bread Production: Sources, Technological and Sensory Aspects, Enhancing Strategies and Constraints

The recognized contribution of antioxidant compounds to overall health maintenance and spotted deficiencies in celiac patients' diets has driven more intensive research regarding antioxidant compounds' inclusion in gluten-free bread (GFB) production during the last decade. The presented review gathered information that provided insights into plant-based antioxidant sources which are applicable in GFB production through the resulting changes in the technological, sensory, and nutritional quality of the resulting antioxidant-enriched GFB. The influence of the bread-making process on the antioxidant compounds' content alteration and applied methods for their quantification in GFB matrices were also discussed, together with strategies for enhancing the antioxidant compounds' content, their bioaccessibility, and their bioavailability, highlighting the existing contradictions and constraints. The addition of plant-based antioxidant compounds generally improved the antioxidant content and activity of GFB, without a profound detrimental effect on its technological quality and sensory acceptability, and with the extent of the improvement being dependent on the source richness and the amount added. The determination of a pertinent amount and source of plant-based antioxidant material that will result in the production of GFB with desirable nutritional, sensory, and technological quality, as well as biological activity, remains a challenge to be combated by elucidation of the potential mechanism of action and by the standardization of quantification methods for antioxidant compounds.

The Improved Quality of Gluten-Free Bread Due to the Use of Flaxseed Oil Cake: A Comprehensive Study Evaluating Nutritional Value, Technological Properties, and Sensory Quality

The development of gluten-free bakery products, the quality of which is comparable to the quality of regular wheat-based products, remains a technological challenge. In this study, flaxseed oil cake (FOC), a by-product of flaxseed oil extraction and a source of nutritional and functional compounds, was used as an ingredient in the experimental bread formulation as partial replacement of starches (5%, 15%, and 30%). The gluten-free breads (GFBs) were evaluated for technological parameters, nutritional value, and sensory quality. Compared with the control, all FOC-enhanced GFBs were significantly (p < 0.05) richer in proteins, fat, and dietary fibre, with an increase that was proportional to the concentration of FOC in the formulation. At low-to-moderate levels (5% and 15%), FOC improved the specific volume, texture characteristics (reduced crumb hardness, gumminess, and chewiness), and appearance of GFBs, which allowed us to ameliorate its sensory features, but at 30% of FOC, the quality of the crumb texture decreased significantly (p < 0.005). Among the experimental GFBs, FOC15% exhibited improved technological characteristics and was rated by the sensory panel as the best in terms of overall quality. The results of the conducted research highlighted the benefits of incorporating FOC into GFB as a promising approach to developing a palatable, high-quality bakery product that may be a healthier option for individuals on a gluten-free diet, offering nutritional benefits. Nevertheless, it should be emphasised that the amount of FOC in GFB requires careful regulation.

Spray-Drying Impact the Physicochemical Properties and Formation of Maillard Reaction Products Contributing to Antioxidant Activity of Camelina Press Cake Extract

Spray-drying is one of the most popular techniques in the food industry for converting liquid material from a fluid state into a form of dried particles to produce encapsulated or instant products. Instant products are considered as convenient foods; moreover, the goal of encapsulation is to close the bioactive compounds in a shell, preventing them from being affected by environmental factors. The purpose of this study was to examine the influence of spray-drying conditions, in particular three inlet temperatures, on the physicochemical and antioxidant properties of powders obtained from Camelina Press Cake Extract (CPE). The CPE was spray-dried at 140 °C, 160 °C and 180 °C. The solubility, Carr and Hausner Indexes, tapped densities and water activity of the powders were analyzed. The structural changes were also detected using FTIR spectroscopy. Additionally, the characteristics of the initial and reconstituted samples and their rheological properties were evaluated. The antioxidant potential, total polyphenols and flavonoids content, free amino acids, and the Maillard reaction products contents in the spray-dried powders were also evaluated. The results indicate a cascade of changes between the initial and reconstituted samples, and important changes in the bioactive potential of samples. The inlet temperature significantly influenced the solubility, flowability and particle sizes of the powders, as well as Maillard products formation. The results of the rheological measurements illustrate the changes after the reconstitution of extracts. This study indicates the optimal parameters of CPE spray-drying, those that yield favorable physicochemical and functional values, which may open up a promising path for CPE valorization, indicating its potential and the possibilities of its use.

Effect of Flaxseed Oil Cake Extract on the Microbial Quality, Texture and Shelf Life of Gluten-Free Bread

Extending the shelf life of gluten-free bread (GFB) is a challenge. Mainly due to the ingredients used and their characteristics, GFB has numerous drawbacks such as unsatisfactory texture and rapid staling beyond a low nutritional value. In the present study, flaxseed oil cake extract (FOCE) was used to replace water (25-100%) in GFB formulations in order to test FOCE's potential to reduce GFB staling and extend microbial stability. Texture (TPA test), water activity (LF NMR), acidity (pH measurements) and microbiological quality of GFBs were tested. Moreover, the content of a lignan with broad health-promoting potential, secoisolariciresinol diglucoside (SDG), in GFB with FOCE was analyzed. The results showed that the use of FOCE enriched experimental GFB in valuable SDG (217-525 µg/100 g DM) while not causing adverse microbiological changes. A moderate level (25-50%) of FOCE did not change the main texture parameters of GFB stored for 72 h, the quality of which was comparable to control bread without FOCE. Meanwhile, higher proportions of FOCE (75-100% of water replacement) shortened GFB shelf life as determined by water activity and texture profile, suggesting that GFB with FOCE should be consumed fresh. To summarize, FOCE at moderate levels can add value to GFBs without causing a drop in quality, while still fitting in with the idea of zero waste and the circular economy.

Nutritional facts regarding commercially available gluten-free bread worldwide: Recent advances and future challenges

Recently, there has been an increase in demand for gluten-free (GF) products due to the growing number of gluten-intolerant and healthy individuals choosing to follow a gluten-free diet. Gluten-free bread (GFB) is a staple food product; therefore, many recent studies have reported the nutritional properties of GFB. However, an overview of the current ingredients and nutritional labeling of GFB worldwide has not yet been provided. This review aimed to gather the latest information regarding the most used ingredients in GFB formulations and the nutritional quality of these products from different countries, based on studies published in the last decade (2010-2020). Our analysis showed that GFB had a lower protein and a higher fat content than gluten-containing bread, and the dietary fiber content was highly variable between countries. Some studies have revealed a high glycaemic index in most products, which is associated with the extensive use of rice flour and starch as the main ingredients in GFB formulation. Label information presented significant differences from the data obtained through the chemical analysis of fiber and other nutritional components. Micronutrient fortification is not common in the GFB. The nutritional quality of commercial GFB is a crucial issue that needs to be addressed.

Daily oligofructose-enriched inulin intake impacts bone turnover markers but not the cytokine profile in pediatric patients with celiac disease on a gluten-free diet: Results of a randomised, placebo-controlled pilot study

BACKGROUND

Bone metabolism disturbances are commonly observed in patients with newly diagnosed celiac disease (CD). The only available treatment for CD-the intake of a gluten-free diet (GFD)-has been found to be insufficient in effectively improving bone health in some patients. Therefore, there is an urgent need to modify the GFD so as to allow for the provision of all the necessary nutrients and improved absorption. Prebiotics intake reportedly improves the absorption of bone-related vitamin D and calcium as well as bone metabolism. The effect of prebiotic intake on bone health in CD patients has not been studied yet. This study aimed to evaluate the effect of oligofructose-enriched inulin intake on bone metabolism and immune response in children with CD on a GFD.

METHODS

A total of 34 children with CD were randomised into two groups receiving 10 g of oligofructose-enriched inulin (Synergy 1) or a placebo (maltodextrin) for three months, together with a strict GFD. The children's bone metabolism marker levels and cytokine profiles were analysed before and after the intervention.

RESULTS

After supplementation, the concentration of osteocalcin increased significantly in children receiving Synergy 1, while the concentration of bone alkaline phosphatase increased in both groups, independent of supplementation. After the intervention, the level of pyridinoline increased significantly in the placebo group, resulting in a concentration that was two times higher than that in the Synergy 1 group, in which it remained stable. Moreover, the plasma concentrations of N-terminal telopeptides of type I collagen decreased in both the groups, whereas the tartrate-resistant acid phosphatase 5b level increased particularly in the Synergy 1 group. The intervention did not lead to immunological response changes.

CONCLUSIONS

The proposed supplementation beneficially altered bone metabolism, through increased bone formation rates and decreased bone resorption process rates. Supplementation of GFD with prebiotic oligofructose-enriched inulin may be a promising auxiliary therapy for bone metabolism improvements in children with CD.

The Profile of Urinary Headspace Volatile Organic Compounds After 12-Week Intake of Oligofructose-Enriched Inulin by Children and Adolescents with Celiac Disease on a Gluten-Free Diet: Results of a Pilot, Randomized, Placebo-Controlled Clinical Trial

The concentration of volatile organic compounds (VOCs) can inform about the metabolic condition of the body. In the small intestine of untreated persons with celiac disease (CD), chronic inflammation can occur, leading to nutritional deficiencies, and consequently to functional impairments of the whole body. Metabolomic studies showed differences in the profile of VOCs in biological fluids of patients with CD in comparison to healthy persons; however, there is scarce quantitative and nutritional intervention information. The aim of this study was to evaluate the effect of the supplementation of a gluten-free diet (GFD) with prebiotic oligofructose-enriched inulin (Synergy 1) on the concentration of VOCs in the urine of children and adolescents with CD. Twenty-three participants were randomized to the group receiving Synergy 1 (10 g per day) or placebo for 12 weeks. Urinary VOCs were analyzed using solid-phase microextraction and gas chromatography⁻mass spectrometry. Sixteen compounds were identified and quantified in urine samples. The supplementation of GFD with Synergy 1 resulted in an average concentration drop (36%) of benzaldehyde in urine samples. In summary, Synergy 1, applied as a supplement of GFD for 12 weeks had a moderate impact on the VOC concentrations in the urine of children with CD.

A Randomized, Placebo-Controlled, Pilot Clinical Trial to Evaluate the Effect of Supplementation with Prebiotic Synergy 1 on Iron Homeostasis in Children and Adolescents with Celiac Disease Treated with a Gluten-Free Diet

Iron deficiency anemia (IDA) occurs in 15–46% of patients with celiac disease (CD), and in some cases, it may be its only manifestation. Studies in animal models have shown that prebiotics, including inulin, may help to increase intestinal absorption of iron. The aim of this study was to evaluate the effect of a prebiotic, oligofructose-enriched inulin (Synergy 1), on iron homeostasis in non-anemic children and adolescents with celiac disease (CD) in association with a gluten-free diet (GFD). Thirty-four CD patients (4–18 years old) were randomized into two groups receiving Synergy 1 (10 g/day) or a placebo (maltodextrin) for three months. Before and after intervention, blood samples were collected from all patients for assessment of blood morphology, biochemical parameters and serum hepcidin concentration. We found that serum hepcidin concentration after the intervention was significantly decreased by 60.9% (p = 0.046) in the Synergy 1 group, whereas no significant difference was observed in the placebo group. No differences in morphological and biochemical blood parameters (including ferritin, hemoglobin and C-reactive protein (CRP)) were observed after intervention in either group. Given that hepcidin decrease may improve intestinal iron absorption, these results warrant further investigation in a larger cohort and especially in patients with IDA.

Beneficial Effect of Oligofructose-Enriched Inulin on Vitamin D and E Status in Children with Celiac Disease on a Long-Term Gluten-Free Diet: A Preliminary Randomized, Placebo-Controlled Nutritional Intervention Study

Prebiotics have been shown to improve absorption of some nutrients, including vitamins. This pilot study evaluated the effect of the prebiotic oligofructose-enriched inulin (Synergy 1) on fat-soluble vitamins status, parathormone, and calcium-related elements in pediatric celiac disease (CD) patients (n = 34) on a strict gluten-free diet (GFD). Participants were randomized into a group receiving 10 g of Synergy 1 or placebo (maltodextrin) together with a GFD. At baseline and after 3 months of intervention, 25-hydroxyvitamin D [25(OH)D], parathormone, vitamin E and A, calcium, phosphate, magnesium, total protein, and albumin were determined. Concentration of 25(OH)D increased significantly (p < 0.05) by 42% in CD patients receiving Synergy 1 in GFD, whereas no change was observed in placebo. Vitamin D status reached an optimal level in 46% of patients receiving Synergy 1. No significant difference in parathormone, calcium, and phosphate levels was observed. Concentration of vitamin E increased significantly (p < 0.05) by 19% in patients receiving Synergy 1, but not in the placebo. Vitamin A levels were not changed. Supplementation of GFD with Synergy 1 improved vitamin D and vitamin E status in children and adolescents with CD and could be considered a novel complementary method of management of fat-soluble vitamins deficiency in pediatric CD patients.

A targeted metabolomic protocol for quantitative analysis of volatile organic compounds in urine of children with celiac disease

Volatile organic compounds (VOCs) in biological samples have gained popularity for disease monitoring and diagnosis. Celiac disease (CD) is one of the many prevalent health conditions which are challenging to diagnose. The aim of this study was to optimize a solid phase microextraction followed by gas chromatography-mass spectrometry, for quantitative analysis of a wide range of VOCs in the urine of patients with CD. Multivariate design of experiment was used to optimize the extraction conditions for the analysis of 15 urinary VOCs. Based on the performed experiments, extraction using 2.98 g of sodium chloride and 21 μL of 6 M hydrochloric acid for 15 min at 30 °C, using a CAR/PDMS fiber in headspace mode was found to be the most effective procedure for the analysis of the selected biomarkers. It was also demonstrated that the proposed method could distinguish between children with CD and healthy children based on the profile of VOCs. It is believed that quantitative analysis of these biomarkers will extend our understanding of CD and could be used for monitoring in patients under treatment.

The effect of oligofructose-enriched inulin supplementation on gut microbiota, nutritional status and gastrointestinal symptoms in paediatric coeliac disease patients on a gluten-free diet: study protocol for a pilot randomized controlled trial

Background

A lifelong gluten-free diet (GFD) is regarded as the only proven and accepted therapy for coeliac disease (CD). However, even patients who strictly follow a GFD often suffer from intestinal symptoms and malabsorption. Selective modulation of intestinal microbiota with prebiotics could remedy various symptoms associated with CD. The use of prebiotics in the treatment of intestinal diseases remains insufficiently investigated. To our knowledge, this study makes the first attempt to evaluate the effect of prebiotic supplementation on gastrointestinal symptoms and nutritional status of children with CD. We hypothesized that adherence to a GFD supplemented with oligofructose-enriched inulin (Synergy 1) would deliver health benefits to children suffering from CD without any side effects, and that it would alleviate intestinal inflammation, restore and stabilize gut microbial balance and reverse nutritional deficiencies through enhanced absorption of vitamins and minerals.

Methods

A randomized, placebo-controlled clinical trial was designed to assess the impact of the Synergy 1 on paediatric CD patients following a GFD. We randomized 34 children diagnosed with CD into an intervention group receiving 10 g of the Synergy 1 supplement daily and a placebo group (receiving maltodextrin) during a 12-week nutritional intervention. Selected biochemical parameters, nutritional status and the characteristics of faecal bacteria will be determined in samples collected before and after the intervention. Analysis of vitamins and amino acids concentration in biological fluids will allow to assess the dietary intake of crucial nutrients. The compliance to a GFD will be confirmed by a Food Frequency Questionnaire (FFQ-6) and the analysis of serum anti-tissue transglutaminase and faecal gluten immunogenic peptides (GIP).

Conclusion

The identification of the beneficial effects of the Synergy 1 supplement on children with CD could have important implications for nutritional recommendations for CD patients and for alleviating the harmful effects of the disease.

Trial registration

ClinicalTrials.gov Registration Number: NCT03064997.

Electronic supplementary material

The online version of this article (doi:10.1186/s12937-017-0268-z) contains supplementary material, which is available to authorized users.

Administration of Inulin-Supplemented Gluten-Free Diet Modified Calcium Absorption and Caecal Microbiota in Rats in a Calcium-Dependent Manner

In coeliac disease (CD), the risk of adverse calcium balance and reduced bone density is induced mainly by the disease, but also by a gluten-free diet (GFD), the only accepted CD therapy. Prebiotics through the beneficial impact on intestinal microbiota may stimulate calcium (Ca) absorption. In the present study, we hypothesised that the dietary inulin in GFD would influence positively the intestinal microbiota, and by that will stimulate the absorption of calcium (Ca), especially in the conditions of Ca malnutrition. In a six-weeks nutritional experiment on growing a significant (p < 0.05) luminal acidification, decrease in ammonia concentration and stimulation of short chain fatty acids formation indicated inulin-mediated beneficial effects on the caecal microbiota. However, the effect of inulin on characteristics of intestinal microbiota and mineral utilization depended on the dietary Ca intake from GFDs. Inulin stimulated bifidobacteria, in particular B. animalis species, only if a recommended amount of Ca was provided. Most benefits to mineral utilization from inulin consumption were seen in rats fed Ca-restricted GFD where it increased the relative Ca absorption. Administration of inulin to a GFDs could be a promising dietary strategy for beneficial modulation of intestinal ecosystem and by that for the improvement the Ca absorption.

Inulin and fructooligosaccharide affect in vitro calcium uptake and absorption from calcium-enriched gluten-free bread

Compromised intestinal calcium absorption affecting a deterioration of bone state is a sign of coeliac disease. Experimental calcium-fortified gluten-free bread (GFB) of improved calcium bioavailability could increase calcium content in the diets of coeliac disease patients, allowing them to obtain the amount of calcium they need for therapeutic use. Prebiotics, including inulin-type fructans (IFs) have a beneficial effect on calcium bioavailability. In the present study, the in vitro model composed of the intestinal-like Caco-2 cells and the human intestinal bacteria (Lactobacillus, Enterococcus and Enterobacteriaceae) were used to analyse the effect of inulin and fructooligosaccharide (FOS) of different chain lengths, on calcium uptake and absorption from experimental GFB. Analysed IFs, especially short-chain FOS, significantly (p < 0.05) increased cellular calcium uptake from GFB digest and stimulated the intestinal bacteria applied in the cultures to the intensive synthesis of organic acids. In particular, the concentration of butyric, valeric and lactic acids increased significantly. Similarly, in the calcium absorption experiment, IFs increased the cellular calcium retention but concomitantly reduced its content in basolateral filtrates. The results obtained suggest that the applied IFs affected differentially calcium uptake and absorption from the experimental calcium-enriched GFB, therefore a further study is needed to assess whether these observations made in vitro contribute to IF effects on calcium absorption from experimental GFB in vivo.

Calcium in Gluten-Free Life: Health-Related and Nutritional Implications

Calcium deficiency and metabolic bone diseases are a frequent co-morbidity of coeliac disease (CD). Gluten-free diet (GFD) is the only effective treatment of CD. However, CD patients on the strict GFD consume less than the recommended amounts of calcium. In this review, the main etiological factors responsible for calcium deficiency in CD were presented. Additionally, the research on the application of calcium supplements in the gluten-free breadmaking was reviewed, and its effect on the technological and sensory properties of baked products was indicated. Calcium-fortified gluten-free products could increase the calcium content in the diet of CD patients, supplying the amount of calcium they need for prophylactic or therapeutic use. Apart from this, the consumption of the naturally GF products as well as functional ingredients beneficially affecting calcium absorption need to be encouraged.

Pathologic bone alterations in celiac disease: etiology, epidemiology, and treatment

Low bone mineral density (BMD), osteopenia, and osteoporosis are frequent complications of celiac disease (CD). The etiology of pathologic bone alterations in CD is multifactorial; however, two main mechanisms are involved: intestinal malabsorption and chronic inflammation. A strict gluten-free diet (GFD) is thought to be the only effective treatment for CD; but treating bone complications related to CD remains complex. The objective of this review is to elucidate the bones problems related to CD and to increase awareness of osteoporosis development, considered as a sign of atypical CD presentation. Currently, a question of whether GFD alone is an effective treatment to correct the bone alterations in patients with CD is under debate. This review presents factors contributing to pathologic bone derangement, recent research on the epidemiology of low BMD, osteoporosis, and fractures, and the treatment of bone problems in patients with CD. The roles of calcium and transport mechanisms are additionally presented.

Application of dairy proteins as technological and nutritional improvers of calcium-supplemented gluten-free bread

Effect of dairy proteins on gluten-free dough behavior, and nutritional and technological properties of gluten-free bread was evaluated. Experimental doughs, containing dairy powders, showed low consistency. Obtained gluten-free breads were rich in proteins, and, regarding the energy value delivered by proteins, they could be considered as a source of proteins or high in proteins. Applied dairy proteins affected the technological properties of experimental breads causing a significant (p < 0.05) increase of the specific volume, crust darkening, and crumb lightness, depending on the dairy supplementation level, rather than the protein type. Dairy proteins incorporated at a 12% level, significantly (p < 0.05) decreased the hardness; nevertheless, the highest amount of proteins tested led to the opposite effect. These results indicate that milk proteins tested could be successfully added to gluten-free bread with beneficial effects on technological and nutritional properties.

Native and microwaved bean and pea starch preparations: physiological effects on the intestinal ecosystem, caecal tissue and serum lipids in rats

Dietary beans and peas provide fibre, resistant starch and other nutrients that are often lacking in the human diet. The influence of native starches of beans and peas (and microwaved preparations) on N utilisation, biochemical indices in blood serum and caecal ecosystem state (SCFA, bacterial enzymes, micro-organisms) was studied in vivo. The native pea starch contained more resistant starch compared with its bean counterpart (31 v. 17 %); however, processing decreased these amounts to 25 v. 10 %. N digestibility was found to decrease considerably in all experimental groups. A considerable reduction was observed in glucose and total cholesterol concentration in rat blood serum as a result of feeding both dietary legume starch preparations under microwave treatment. This indicates that starch of bean origin activated glycolytic bacterial enzymes; however, all the analysed starches were found to reduce the activity of beta-glucuronidase. In addition, both dietary bean starches significantly induced the formation of SCFA in the caecal digesta. As compared with the control group, a significant decrease in the pH of caecal and colonic digesta was demonstrated for both bean starch preparations. In comparison with the diet with native pea starch, its microwaved preparation reduced the concentrations of acetic, butyric and propionic acids among caecal SCFA and increased the pH of caecal and colonic digesta. The atherogenic index was significantly lower in rats fed microwaved pea starch. All investigated starch preparations increased the population of Bifidobacterium spp. in caecal digesta, but were also good substrates for opportunistic Enterococcus or Escherichia coli.

Native wheat, potato and pea starches and their physically modified preparations tested in vitro as the substrates for selected Bifidobacterium strains

The wheat, potato and pea starches subjected to physical modification were studied in vitro as a substrate for selected Bifidobacterium strains (Bifidobacterium breve KN14, Bifidobacterium animalis KS20a1). The effects of these substrates on bifidobacterial growth, acidifying activity, metabolic end-products and changes in starch microstructure were assayed after 24-h fermentation. Physically modified starch preparations were better utilized substrates for growth of Bifidobacterium monocultures, in comparison with native starches. Lactic acid occurred in the highest concentration in the culture of B. breve KN14 (55-104 micromol/100 ml), whereas acetic acid was highest in the culture of B. animalis KS20a1 (329-378 micromol/100 ml). The microstructure pictures showed meaningful differences between native and modified starches stemmed from the enzymatic action of examined Bifidobacterium strains during fermentation. Obtained results confirmed the stimulation of growth and acidifying activity of selected Bifidobacterium strains by investigated physically modified starches in comparison with native starch.