Innovative approaches towards improved gluten-free bread properties

The evidenced relevance of dietary fibers (DF) as functional ingredients shifted the research focus towards their incorporation into gluten-free (GF) bread, aiming to attain the DF contents required for the manifestation of health benefits. Numerous studies addressing the inclusion of DF from diverse sources rendered useful information regarding the role of DF in GF batter’s rheological properties, as well as the end product’s technological and nutritional qualities. The presented comprehensive review aspires to provide insight into the changes in fiber-enriched GF batter’s fundamental rheological properties, and technological, sensory, and nutritional GF bread quality from the insoluble and soluble DF (IDF and SDF) perspective. Different mechanisms for understanding IDF and SDF action on GF batter and bread were discussed. In general, IDF and SDF can enhance, but also diminish, the properties of GF batter and bread, depending on their addition level and the presence of available water in the GF system. However, it was seen that SDF addition provides a more homogenous GF batter structure, leading to bread with higher volumes and softer crumb, compared to IDF. The sensory properties of fiber-enriched GF breads were acceptable in most cases when the inclusion level was up to 7 g/100 g, regardless of the fiber type, enabling the labeling of the bread as a source of fiber.

The rheological properties of Gluten-Free (GF) batter are an important factor to consider for designing GF bread recipes, which is critical when they are baked by ohmic heating. This research demonstrated that batter properties are not only significantly modified by the starch:water ratio, but also greatly by the starch source and structure, which influenced its physical properties (e.g., water holding capacity, swelling power, solubility, starch damage, and pasting properties). This study aimed to investigate the role of GF starches (corn, wheat, potato, cassava) and flours (rice and buckwheat), as well as the rheological behavior of GF batter and the final bread quality after baking with ohmic heating. The starch (or flour) to water ratios were 1:0.9, 1:1.3, and 1:1.7, while buckwheat needed higher water ratios of 1:1, 1:1.5, and 1:2. The attempt was to thoroughly understand the interaction between the rheological properties and ohmic baking and to define a suitable viscosity range for this processing approach. All batters consistently exhibited shear-thinning and dominant viscous behavior. Between viscosity and ohmic-heated bread properties, a non-linear relationship was observed. These breads were generally higher in volume and softer in texture as opposed to conventional baked bread. Two categories of required water content or viscosity ranges were defined for estimating final ohmic-heated GF bread properties: low water content with a viscosity range of 47.12–56.20 Pa·s for B-type starches (tuber starches) and medium water content with a low to medium viscosity range of 2.29–15.86 Pa·s for A-type starches (cereal starches). This fact showed that viscosity played a critical role in determining GF bread structure and crumb properties. This finding could be useful for further research to design GF batter viscosities for tailored bread quality.

The objective is to verify if gluten-free (GF) and gluten-containing (G) breads differ in their sodium content and lipid profile. Samples of GF (n = 20) and G (n = 14) sliced white sandwich bread of commercial brands most frequently consumed in Spain were collected. The fatty acid (FA) composition and the contents of sodium, fat, cholesterol and phytosterols were determined. Sodium, fat and cholesterol contents were significantly higher in GF bread. The FA composition also differed, while G breads declared in most instances the use of sunflower oil as fat ingredient and presented a higher polyunsaturated FA percentage; GF breads declared a wide variety of fats and oils as ingredients (coconut, palm, olive, sunflower, etc.) which was reflected in their FA profile. Cholesterol content was higher in GF bread because five samples declared the use of whole egg, while G samples did not include any egg product in their formulas. Phytosterol content was higher in G bread but its variability was greater in GF bread. In conclusion, nutritional quality of GF bread varied depending on the ingredients used and might be lower than that of G bread. However, these differences in composition could be reduced or eliminated through changes in the formulation of GF bread. Moreover, the comparison of the results obtained in our laboratory for fat and salt content with the declared contents on the labels showed a much higher deviation for GF samples and it can be concluded that the quality of the nutritional information declared was lower in GF samples.

Effect of arabinoxylans and laccase on batter rheology and quality of yeast-leavened gluten-free breads

The viscosity of gluten-free (GF) batter significantly influences GF bread quality. This study attempts to understand how the rheological properties of GF batter are affected by the type of starch and the amount of water and how they influence GF bread properties when baked with two methods (conventional oven, ohmic heating). For this purpose, the physical and chemical properties of different starches (corn, wheat, potato, cassava) and GF flours (rice, buckwheat) were evaluated. Rheological behavior of GF batter was not only influenced by the starch:water ratio, but also greatly by the starch source and structure, which influenced its physical properties (e.g., water holding capacity, swelling power, solubility, starch damage, and pasting properties). All batters consistently exhibited shear-thinning and dominant viscous behavior. Between viscosity and ohmic-heated bread properties, a non-linear relationship was observed. Two categories of required water content or viscosity ranges were defined for estimating final GF bread properties: low water content with a viscosity range of 47.12–56.20 Pa·s for B-type starches, and medium water content with a low to medium viscosity range of 2.29–15.86 Pa·s for A-type starches. This finding could be useful for further research to design GF batter viscosities for tailored bread quality.

The growing awareness of gluten-related health issues, such as celiac disease, non-celiac gluten sensitivity, and wheat allergies, has led to an increased demand for gluten-free (GF) bread. Producing GF bread, however, presents significant challenges due to the absence of gluten, which plays a crucial role in the texture and structure of traditional bread. Recent research efforts have been directed towards addressing these challenges through the use of alternative ingredients, the adoption of novel processing techniques, and the implementation of quality improvement strategies. This review critically examines the current state of GF bread production, focusing on the difficulties in replicating the properties of conventional bread and exploring various approaches to enhance product quality, including sourdough technology, alternative polymer networks such as arabinoxylans (AXs), enzyme technology, and high hydrostatic pressure (HHP). Key issues include the use of alternative flours, starches, hydrocolloids, enzyme applications, fermentation processes, non-conventional baking and packaging technologies, with particular attention to their impact on sensory and nutritional attributes. The findings suggest that while progress has been made, ongoing research is essential to meet consumer expectations for high-quality GF bread.

Information on what drives consumers to like or dislike bread is needed to provide insight on developing gluten-free (GF) bread, using indigenous and sustainable crops in Africa, such as sorghum and millet. Consumer attitudes toward the health and taste aspects of food are major drivers of food choices. The objectives of this work were (1) to determine the health and taste attitudes (HTAs) and general perceptions of a group of millennial consumers in South Africa (n = 354), concerning GF breads; and (2) to determine whether HTAs affect the acceptability of sensory properties of commercial GF breads, as assessed by consumers (n = 173), under informed and uninformed conditions. Mean scores of the taste factors were higher compared to health factors, indicating a greater taste orientation. The sensory properties of standard wheat breads were preferred over two commercial GF breads, irrespective of the health/taste interests of consumers, or if they were informed/uninformed about the nature of the bread (GF or wheat). Knowledge that bread samples were GF reduced only the acceptability of the aroma of GF bread. GF bread was perceived as healthier, but less tasty. For this group of millennials, the sensory properties of bread was the main driver of choice.

Recently there has been increasing interest in the production of gluten-free (GF) foods and studies on minor cereals and pseudocereals without celiac activity in order to fulfill the specific needs of people affected by celiac disease. GF bread, pasta, biscuits are usually manufactured using different combinations of thickenings and particular food processing procedures that could affect starch digestibility. Carbohydrates, mainly starch from cereals, play an important part in a balanced diet, and dietary guidelines suggest a diet with low glycemic index foods, that is to say rich in slowly digested carbohydrates. The present study was aimed at evaluating: 1) the importance of some GF food characteristics in relation to their effects on in vitro starch accessibility to digestion, in comparison with traditional gluten products; 2) the in vivo metabolic responses to GF foods. Firstly, starch digestibility of several products was evaluated in vitro. Then, an in vivo study was performed on a group of healthy volunteers. Postprandial glucose and insulin responses were evaluated after administration of three GF foods and traditional bread. Triglycerides and free fatty acids (FFA) were also evaluated. Attempts were also made to explore differences in metabolic responses to GF foods in healthy subjects with respect to celiac subjects. The area under the curve (AUC) of digested starch of GF bread was slightly higher than that of the traditional counterpart. No significant difference was observed in AUCs of digested starch between GF pasta and the traditional pasta. The AUCs of digested starch of quinoa and the two samples of pasta were not statistically different. Significant differences were observed between GF bread and bread-like products. Statistic differences in glucose responses to GF pasta were observed between healthy and celiac subjects. In healthy subjects, the AUCs of glucose response after GF bread were higher than those after bread with gluten. No significant differences were observed between the AUCs of insulin responses to all products tested. Glycemic index (GI) for GF pasta was similar to GI for GF bread while GI for quinoa was slightly lower than that of GF pasta and bread. Two-way ANOVA revealed that quinoa induced lower FFA levels with respect to GF pasta. In addition, triglyceride concentrations were significantly reduced for quinoa with respect to GF bread and bread. Our results indicate that the different formulations and the food processing procedures used in the manufacturing of GF products may affect the rate of starch digestion both in vitro and in vivo. It may be worthwhile improving the formulation of these products. Furthermore, quinoa seems to represent a potential alternative to traditional foods, even if further and larger studies are required to demonstrate its hypoglycemic effects.

Gluten-free (GF) staple food products, such as those from baking, are commonly presented with a low nutrient profile and are calorie-dense. The incorporation of nutrient-rich ingredients in the formulas, however, frequently led to physical and sensory impairments in the final products in spite of including structure-forming agents with the ability to mimic the gluten functionality. The aim of the present doctoral thesis is the study and evaluation of alternative and physically modified ingredients of high nutritional value for its inclusion in gluten-free baked product formulas. Initially, the use of a low-cost by-product such as buckwheat (BW) hulls to increase the dietary fibre content of gluten-free bread was explored. In the experimental development, the use of two different particle sizes (62.7 µm vs 307 µm; D50) and two addition levels (3 – 6 %) of BW hull particles in a GF bread formulation was tested. The addition of BW hull particles in the GF rice-based bread formulation increased the viscoelastic moduli values of the doughs by increasing the percentage of addition and by using the smaller BW hull particle size. All the resulting breads showed a significant increase in dietary fibre content together with an increase in phenol content and antioxidant capacity. Furthermore, the addition of 3% of BW hull particles at the smallest particle size led to breads without alterations in physical properties and with appropriate sensory attributes. On the other hand, the physical treatment of high hydrostatic pressure (HHP) was also studied to promote tailor-made techno-functional properties in a whole flour making it suitable for GF baking products. In the initial stage of this study, the evaluation of combined treatments of pre-soaking (4h, 40ºC) and pressure application in a single or double cycle of the HHP treatment (600 MPa, 30 min.) on unhulled buckwheat (BW) kernels was carried out. The resulting flours obtained from the combined treatments showed higher water absorption capacity and thermal stability in the pasting profiles. A lower enthalpy of gelatinisation was also observed and attributed to partial gelatinisation induced by the treatments. These flours also showed higher phenol content. In the next stage, the influence of the HHP processing conditions of holding time (0/5/15 min.) and pressure level (300/600 MPa) on the unhulled and pre-soaked BW kernels was evaluated. The flours resulting from the most intensive treatment conditions (600 MPa, 15 min.) showed increasing values in hydration properties and higher thermal stability. In addition, they showed significant increases in antioxidant capacity. This flour was also used to partially replace white rice flour in a GF bread formulation. The resulting breads made with the modified BW flour showed higher specific volume and lower crumb firmness than their counterparts made with untreated BW flour. The combined treatments of HHP (600 MPa) with increasing holding times and pre-soaking were also applied to rough rice. Similar to the BW flours obtained after intensive HHP treatment conditions, the brown rice flours resulting from the combined treatments showed increased water absorption capacity and lower viscosity values in their pasty profiles with increased thermal stability. Increasing the treatment holding time resulted in an increase in phenol content, antioxidant capacity and vitamin content in the resulting flours. GF breads made by replacing white rice flour with HHP-modified brown rice (600 MPa, 15 min.) resulted in breads with higher specific volumes and softer crumb textures compared to those made with a native brown rice flour. Based on these results, this study shows that alternative approaches such as the inclusion of fibre-rich by-products or physically-modified GF whole flour ingredients from HHP treatments could be effective tools for technologically and nutritionally improving the quality of GF breads.

The replacement of gluten in cereal-based goods still represents a significant technological challenge, and obtaining high-quality gluten-free (GF) breads brings about the search for ingredients and technologies able to improve the overall features of these products. Even if the use of sourdough has been extensively studied for the traditional baking, thanks to its positive effects on the product associated with the metabolic activities of sourdough-resident microorganisms; only in recent times, similar attempts have been made in GF baking. GF bread, in fact, is more generally produced by a straight-dough process, using compressed yeast as leavening agent. This research aimed to compare the properties of GF doughs and breads obtained using a Type I GF sourdough (GF-SD; in-lab developed), compressed yeast (Saccharomyces cerevisiae; CY), or their mixture (GF-SD + CY) during proofing. There are no studies, in fact, on Type I GF-SD with the stable association between the lactic acid bacterium Lactobacillus sanfranciscensis and the yeast Candida humilis. GF-SD doughs were comparable to CY doughs in terms of height development (adopting a longer fermentation step), and well-developed doughs were obtained in a short time when GF-SD was combined with CY. Despite the lower specific volume and the denser crumb, GF-SD breads were characterized by a more coherent texture, while CY breads were more prone to fracture during storage. Breads leavened with GF-SD + CY showed intermediate features. The promising results coming from the use of the in-lab developed GF-SD thus confirmed the positive effects of adopting the sourdough technology in GF breadmaking, too.

Commercial gluten-free (GF) breads often exhibit low nutritional quality due to limited fiber and bioactive compounds. The enzymatic treatment of vegetable by-products, such as broccoli and artichoke, represents a sustainable strategy to release soluble dietary fiber and phenolic compounds, enhancing the functional value of GF products. Five GF bread formulations were developed: a control bread, breads containing broccoli or artichoke extracts (BB and BA), and breads with enzymatically treated extracts using Viscozyme® L and Celluclast® 1.5 L (BBE and BAE). A commercial GF bread (BC) served as a reference. Nutritional composition, dietary fiber fractions, phenolic content, antioxidant capacity, starch digestibility, physicochemical parameters, and sensory properties were evaluated. Enzymatic treatments significantly improved the nutritional and functional properties of GF breads. Viscozyme L® produced the highest increases in antioxidant capacity and phenolic content (up to 30% higher in FRAP), while Celluclast® 1.5 L generated the highest rise in soluble dietary fiber (up to 2.75 g/100 g) and the best sensory acceptance. Moreover, Celluclast® 1.5 L significantly modified starch digestibility, reducing rapidly digestible starch by 14% and increasing slowly digestible starch by over 150%, suggesting a lower predicted glycemic response. Incorporating the enzyme-treated artichoke and broccoli by-products into GF breads effectively enhances soluble fiber, antioxidant potential, and sensory quality. Among treatments, Celluclast® 1.5 L applied to artichoke proved most effective overall, providing a balanced improvement in nutritional and functional attributes. These findings revealed the potential of Celluclast® 1.5 L-treated artichoke by-products as a source of natural bioactive compounds for developing clean-label, nutritionally enhanced GF breads.

The demand for gluten-free (GF) bread is steadily increasing. However, the production of GF bread with improved baking quality and enhanced nutritional properties remains a challenge. In this study, we investigated the effects of adding psyllium fibre (PSY) in varying proportions to buckwheat flour on the dough characteristics, bread quality, and starch digestion properties of GF bread. Our results demonstrate that incorporating PSY contributes to the formation of a gluten-like network structure in the dough, leading to an increase in the gas holding capacity from 83.67% to 98.50%. The addition of PSY significantly increased the specific volume of the bread from 1.17 mL/g to 3.16 mL/g. Bread containing PSY displayed superior textural characteristics and colour. Our study also revealed that the inclusion of PSY reduced the digestibility of starch in GF bread. These findings highlight the positive impact of incorporating PSY into GF bread, suggesting its potential in guiding the production of GF bread with a lower glycaemic index. This may be particularly beneficial for individuals seeking to regulate their blood sugar levels or adopt a low-glycaemic diet.

The demand for high-quality gluten-free (GF) baked goods is rising. Meeting these needs has been a technological challenge due to the limited functionality of GF ingredients. To help address these, a study was conducted to investigate how different levels of hydrocolloids, their combination, and starch type impacted rheological, textural, and physical properties of GF dough and breads developed with proso millet. The results indicate that hydrocolloid-formulations increased values of storage (G') and loss (G″) moduli with lower shift angle (tan δ) values. Also, hydrocolloid formulated GF bread showed reduced specific volume (1.88-2.88mL/g), compared to wheat bread (3.58mL/g). Additionally, all hydrocolloid formulations with 50% millet starch reported higher values for crust lightness (72.23-75.86) than wheat flour (43.86), with their respective formulations showing a negative shift to redness at both 2% and 3% gum levels. Storage studies showed significant reductions in bread firmness, although this observation was not influenced by hydrocolloid type and formulation level, but vice versa with respect to starch type, where corn/potato and millet starches produced the highest and lowest firmness, respectively. Overall, our results demonstrated that the comparative combination of hydrocolloids and starch with proso millet flour can help develop high-quality GF bread. PRACTICAL APPLICATIONS: The knowledge of how millet flour, a type of gluten-free ingredient, interacts with hydrocolloids and different types of starch is critical to improving the quality attributes of GF bread. This study provides insight into how various GF ingredients modulate the quality attributes of GF bread. The practicality of this is for the GF food industry, which is looking for new ingredients, and the consumer base that is seeking unique and varied GF products.

Summary Batter stabilisation presents a great challenge for gluten‐free (GF) bread, as CO 2 is released during bread‐making process, resulting in small, dense and crumbly breads. Apart from starch, protein plays a crucial role in gas cell stabilisation. This study aims to assess the effect of non‐gluten protein from different sources (plant and animal) on GF batter's rheological behaviour (pasting properties, rheology and foam stability) and on bread properties after baking with conventional and ohmic heating method. Hence, this study evaluated the functional properties (protein solubility, hydrophobicity, sulfhydryl groups, foaming and emulsification properties) of selected non‐gluten protein relevant for foam stabilisation. Furthermore, a correlation matrix was established by involving the functional properties of the proteins and their interaction with starch on batter rheology and bread quality. Among proteins, egg albumin and potato proteins were reported to perform superior functionality in GF bread; in particular, potato protein generated breads with the highest volume for both baking methods, which was potential to replace egg albumin. According to the correlation matrix, protein solubility was required in foaming and emulsification behaviour to improve GF bread properties.

The absence of gluten is a technological challenge that requires the addition of components to replace the unique viscoelastic properties of gluten, thus altering the nutritional composition of gluten-free (GF) breads. Moreover, GF flours may have different compositions as compared to gluten-containing (GC) counterparts because of a different origin. This may impact the nutritional quality of GF diets. The aim of the study is to provide updated analytical data on moisture, fat, and fibre contents in GF flour and bread samples, and compare them with their GC counterparts, as well as to analyse ingredients and how they impact nutritional quality. A total of 30 different flours and 24 types of bread were analysed using AOAC methods. GF cereal flours contain more fat than GC flours (3.5 ± 2.1% vs. 2.5 ± 2.1%, p < 0.001), as well as GF flours from pseudocereals, except for wholemeal buckwheat (2.6 ± 0.1%). Fibre content is lower in GF flours (3.6 ± 3.1% vs. 7.1 ± 3.9%, p = 0.03), except for GF pseudocereal and legume flours. GF breads contain almost twice as much fat 6.6 ± 2.3% vs. 1.4 ± 0.2%, p < 0.001, and 4.2 ± 1.2%, p < 0.001) and fibre (7.3 ± 2.4% vs. 2.8 ± 0.5%, p < 0.001, and 4.9 ± 2.1%, p = 0.002) as GC breads. This is due to the raw materials themselves and to the addition of ingredients, such as regular and high oleic sunflower oil, and psyllium. Fibre ingredients and additives are more frequently used in ready-to-eat GF flours and breads, and more GF breads also contain fat-based ingredients, as compared to GC. Amaranth and chickpea flours are good alternatives to produce breads with better nutritional quality. Analysis of GF products for critical nutrients is peremptory because of continuing technological and nutritional innovation.