Reducing the glycaemic index and increasing the slowly digestible starch content in gluten‐free cereal‐based foods: a review

Commercially available gluten‐free (GF) cereal‐based foods are generally characterised by a lower nutritional quality than their gluten‐containing counterparts, relatively lower resistant starch (RS) content, along with higher glycaemic index (GI) often being reported. To overcome this nutritional imbalance, extensive research has been conducted to investigate the preparation of a new generation of staple GF products. This review reported the main strategies currently adopted in GF cereal‐based food recipes to formulate products with overall slowly digestible starch properties. They are mainly obtained by the utilisation of alternative ingredients to be incorporated into standard food formulation (including native starch and GF flours) or by technological treatments that may contribute to impact starch digestibility. Considering data from in vitro digestion trials, indications suggested that, aiming to obtain a RS content of about 5% (dry weight) and lowering the in vitro GI values, the minimum high amylose starch (amylose >60%) replacement level in GF bread and cookie formulations should be in the order of 20% by weight of total flours. Overall, with respect to un‐substituted GF foods, two‐ to three‐times higher RS contents, along with a parallel in vitro GI decrease (up to ?50%), were obtained for GF pasta and ready‐to‐eat snacks enriched with legume flours at inclusion levels from 40% to 100% by weight of total flours. The use of flours from pseudocereals (e.g., quinoa, amaranth and buckwheat) with and without sourdough did not always guarantee favourably slowly digestible starch GF foods.     

Novel Approaches in Gluten‐Free Breadmaking: Interface between Food Science,Nutrition, and Health

The evidence that celiac disease is one of the commonest food intolerances in the world is driving an increasing demand for gluten‐free foods. However, gluten is a structure‐building protein essential for formulating leavened baked goods. Therefore, obtaining high‐quality gluten‐free bread (GFB) is a technological challenge. This review focuses on contemporary approaches in gluten‐free baking that allow improvements at the structure, texture, acceptability, nutritive value, and shelf life of GFB. Gluten‐free breadmaking is a relatively new, emerging research topic that is attracting worldwide attention in order to develop different kinds of GFB, including regional varieties. Several approaches have been used to understand and improve GFB systems by evaluating different flours and starch sources, ingredients added for nutritional purposes, additives, and technologies or a combination of these elements. Some studies aimed to assess or improve GFB's technological or nutritional properties, while others had multiple objectives. Several studies used food science tools in order to improve technological and sensory quality of GFB, together with nutritional value. Some GFBs are vehicles of nutrients and bioactive compounds. Furthermore, extensive research on interfacing food science, nutrition, and health is needed so that a GFB with both good technological and nutritional properties can be prepared and made more available to those with celiac disease, which will help them adhere to a strict gluten‐free diet, increase social inclusion, and improve their quality of life.     

Gluten‐free bakery and pasta products: prevalence and quality improvement

An increasing demand of gluten‐free (GF) products is caused by a growing number of diagnosed coeliacs and a consumption trend to eliminate allergenic proteins from diet. Driven by the rapidly growing market, comprehensive understanding of GF products is necessary. The purpose of this review was to concisely present an overview of various approaches to improve physicochemical and sensory qualities of GF bread, cake/muffin and pasta/noodle products. Some novel techniques used in GF products were discussed in this review. These techniques included the use of different alternative flours (including GF cereals, pseudo‐cereals, legume flours, fruit and vegetable powders and seafood powders), functional ingredients (including hydrocolloids and gums, emulsifiers, proteins and dietary fibres) and optimal processing (pretreated flour, infrared–microwave combination baking and extrusion cooking). Some recent novel technologies including transgenesis, enzymolysis and fermentation that have been used on GF products were also discussed.     

Characterization of the Bread Made with Durum Wheat Semolina Rendered Gluten Free by Sourdough Biotechnology in Comparison with Commercial Gluten‐Free Products

Durum wheat semolina was fermented with sourdough lactic acid bacteria and fungal proteases aiming at a complete gluten hydrolysis. The gluten‐free (GF) semolina, added with naturally GF ingredients and structuring agents, was used to produce bread (rendered GF bread; rGFB) at industrial level. An integrated approach including the characterization of the main chemical, nutritional, structural, and sensory features was used to compare rGFB to a gluten‐containing bread and to 5 commercial naturally GF breads. High‐performance liquid chromatography was used for free amino acids (FAAs), organic acids, and ethanol analysis. A methanolic extract was used for determining total phenols and antioxidant activity. The bread characterization also included the analysis of dietary fibers, mycotoxins, vitamins, and heavy metals. Beyond chemical analysis, nutritional profile was evaluated considering the in vitro protein digestibility and the predicted glycemic index, while the instrumental texture profile analysis was performed to investigate the structure and the physical/mechanical properties of the baked goods. Beyond the huge potential of market expansion, the main advantages of durum wheat semolina rendered GF can be resumed in the high availability of FAAs, the high protein digestibility, the low starch hydrolysis index, and the better technological properties of bread compared to the commercial GF products currently present on the market. Vitamins, minerals, and dietary fiber profiles are comparable to those of gluten‐containing wheat bread. Also the sensory profile, determined by a panel test, can be considered the most similar to those of conventional baked goods, showing all the sourdough bread classic attributes.     

The role of corn starch,amaranth flour,pea isolate,and Psyllium flour on the rheological properties and the ultrastructure of gluten-free doughs

The removal of gluten from bakery products, in order to produce foods (mainly based on gluten-free cereal flours and starch) for people with celiac disease, impairs dough’s capacity to properly develop during leavening and baking. The main aim of this research was to produce and evaluate some experimental gluten-free (GF) doughs containing different levels of corn starch, amaranth flour (to enhance the nutritional benefits), pea isolate (to increase the protein content) and Psyllium fiber (as thickening agent and fiber source) in order to study the influence of the different ingredients on the rheological properties and on the ultrastructure of the doughs. Psyllium fiber generally enhanced the physical properties of the doughs, due to the film-like structure that it was able to form, and the most complex among the experimental formulations looked promising in terms of final bread technological and nutritional quality even when compared to two different commercial GF mixtures.     

Nutritional enrichment of bakery products by supplementation with nonwheat flours

Bakery products are important ready‐to‐eat processed foods. The nutritional quality of these products is low because of the inferior nutritional composition of wheat grain per se. This is further accentuated with the use of refined flours in their preparations. Nutritional composition of these products can be improved by using quality wheat for milling, increased extraction rates, air classification of flours to obtain protein‐rich nonwheat flours and their products. The flours and protein products of legumes, oilseeds, other cereals, tubers, corn gluten and germ, and rice bran can be used effectively as vegetable protein sources for nutritional enrichment of the bakery products. In this article, recent literature concerning the nutritional composition of major bakery products, sources of vegetable proteins for product enrichment, and modifications in conventional processing methods to maintain the rheological and sensory properties of supplemented bakery products are reviewed critically.     

Technological benefits of inulin-type fructans application in gluten-free products – A review

BackgroundAlthough cereals are used extensively in food products, ingestion of gluten-containing food has been associated with gluten-related disorders in susceptible individuals. Recently, the gluten-free (GF) products are one of the most dynamically growing branches of the food industry. However, many commercially available GF products provide lower level of proteins, dietary fibre, vitamins and minerals, compared with wheat products. To meet the growing demands of GF food consumers, efforts have been made to improve the overall quality of these products. Recently, inulin-type fructans (ITFs) were proposed as the beneficial ingredients of GF products.Scope and approachOver the last decade, the application of ITFs in GF products has been widely explored. Therefore, the aim of this review is to present the current application of ITFs as components of GF products by summarising the existing data concerning their effect on the technological properties and sensory quality of these products in the light of their physicochemical characteristics.Key findings and conclusionsITFs added to the GF products interact with other ingredients and additives. Generally, they have the potential to improve the technological properties and sensory perception of obtained products. The presented facts may provide an inspiration for further intensive work on the improvement of the quality of GF products for the growing number of people struggling with the problem of gluten intolerance.     

In Vitro Starch Digestibility of Commercial Gluten‐Free Pasta: The Role of Ingredients and Origin

Gluten replacement in gluten‐free (GF) products presents major challenges for the food industry in terms of sensorial, technological and nutritional characteristics. The absence of gluten reportedly affects starch digestibility, thus increasing the postprandial glycaemic response. However, the role of ingredients and processing conditions has been addressed only seldom. We investigated the in vitro starch digestibility of 9 commercial GF products (5 Italian pasta and 4 Oriental noodles) differing in formulation and processing conditions. Content of rapidly digestible starch (RDS), slowly digestible starch (SDS), and resistant starch (RS) were assessed and combined with information on starch pasting properties and on the overall protein organization. Oriental noodles presented higher relative levels of RS and RDS than Western‐style pasta, that often had SDS levels compatible with low rates of starch digestion. As regard formulation, presence of multiple ingredients seems to likely increase the RDS level, as did the different protein organization in the various samples.     

An overview of the Italian market for 2015: cooking quality and nutritional value of gluten-free pasta

A roundup of gluten-free (GF) pasta sold in the Italian market in 2015 was characterised throughout cooking behaviour, texture, colour and nutritional value. A preliminary evaluation of cooking quality of the thirty-three available products underlined an extremely heterogeneous technological quality. Eleven categories were, therefore, discriminated based on the main ingredients declared on the labels. Interestingly, the most numerous category (rice and corn) was pulverised on the factorial space indicating highly heterogeneous properties. This result was confirmed throughout multivariate statistics and can be likely due to diversity in ingredients proportions or/and processing. Nutritional evaluation of GF pasta pointed out a good nutritional quality. Therefore, the combination of technological and nutritional analyses demonstrated a huge difference among the analysed pasta samples, which can increase the difficulty of consumers to make their choice, and leaves room for further improvement of GF pasta formulation and productive processing.     

Cookie- Versus Cracker-Baking—What's the Difference? Flour Functionality Requirements Explored by SRC and Alveography

The many differences between cookie- and cracker-baking are discussed and described in terms of the functionality, and functional requirements, of the major biscuit ingredients—flour and sugar. Both types of products are similar in their major ingredients, but different in their formulas and processes. One of the most important and consequential differences between traditional cracker and cookie formulas is sugar (i.e., sucrose) concentration: usually lower than 30% in a typical cracker formula and higher than 30% in a typical cookie formula. Gluten development is facilitated in lower-sugar cracker doughs during mixing and sheeting; this is a critical factor linked to baked-cracker quality. Therefore, soft wheat flours with greater gluten quality and strength are typically preferred for cracker production. In contrast, the concentrated aqueous sugar solutions existing in high-sugar cookie doughs generally act as an antiplasticizer, compared with water alone, so gluten development during dough mixing and starch gelatinization/pasting during baking are delayed or prevented in most cookie systems. Traditional cookies and crackers are low-moisture baked goods, which are desirably made from flours with low water absorption [low water-holding capacity (WHC)], and low levels of damaged starch and water-soluble pentosans (i.e., water-accessible arabinoxylans). Rheological (e.g., alveography) and baking tests are often used to evaluate flour quality for baked-goods applications, but the solvent retention capacity (SRC) method (AACC 56-11) is a better diagnostic tool for predicting the functional contribution of each individual flour functional component, as well as the overall functionality of flours for cookie- and/or cracker-baking.     

Understanding gluten‐free dough for reaching breads with physical quality and nutritional balance

In the last decade the development of gluten‐free foodstuffs has attracted great attention as a result of better diagnoses of coeliac disease and a greater knowledge of the relationship between gluten‐free products and health. The increasing interest has prompted extensive research into the development of gluten‐free foodstuffs that resemble gluten‐containing foods. This review aims to provide some insights on dough functionality and process conditions regarding bread quality and to point out recent research dealing with the nutritional composition of those products. Gluten‐free dough results from the combination of different ingredients, additives, and the processing aids required for building up network structures responsible for bread quality. Some relationships between dough rheology and bread characteristics were established to identify possible predictor parameters. Regarding bread‐making processes, the impact of mixing, dough treatment and baking is stated. Nutritional quality is an important asset when developing gluten‐free breads, and different strategies for improving it are reviewed. Gluten‐free bread quality is dependent on ingredients and additives combination, but also processing can provide a way to improve bread quality. Nutritive value of the gluten‐free breads must be always in mind when setting up recipes, for obtaining nutritionally balanced bread with adequate glycaemic index. © 2014 Society of Chemical Industry     

The role of buckwheat and HPMC on the breadmaking properties of some commercial gluten-free bread mixtures

Although the food industry has risen to the formulation challenges associated with removing gluten from dough, and a number of gluten-free (GF) products are now commercially available, many GF bread formulations are still based on pure starches, resulting in low technological and nutritional quality. The aim of this research was to evaluate the role of buckwheat and HPMC on the breadmaking properties of two commercial GF bread mixtures. A dehulled (DBF) and a puffed (PBF) buckwheat flour were used, and high substitution levels (40%) were tested, with the aim of improving the nutritional value of the final GF breads without decreasing their technological quality. Ten mixtures (2 commercial, 8 experimental) were evaluated. The inclusion of 40% DBF was demonstrated not to reduce but actually improve the baking performances of the commercial GF mixtures. Moreover, the presence of a small amount of PBF, as well as of HPMC, turned out to be useful in limiting both the diffusion and the loss of water from the bread crumb and the interactions between starch and protein macromolecules, resulting in a softer GF bread crumb and reduced staling kinetics during storage.     

Current and Forward‐Looking Approaches to Technological and Nutritional Improvements of Gluten‐Free Bread with Legume Flours: A Critical Review

The gluten‐free market currently offers a range of products which can be safely consumed by patients affected by celiac disease. Nevertheless, challenges for optimal formulation remain on the way in terms of appreciable texture, flavor, and adequate nutritional characteristics. Within that framework, legumes have recently attracted attention among scientists as structure‐ and texture‐forming agents, as source of nutrients and bioactive compounds, and as a low‐glycemic‐index ingredient. This work aims at providing an updated and comprehensive overview of the advantages and disadvantages in the use of legumes in gluten‐free breadmaking. It also shows how legumes can contribute to tackling the main technological, nutritional, and organoleptic challenges. From this critical analysis, it emerged that viscoelastic properties of gluten‐free bread batter can be enhanced by the use of carob germ, chickpea, lupin, and soybean. Gluten‐free bread organoleptic acceptability can be improved by incorporating leguminous flours, such as carob, chickpea, lupin, and soybean. Moreover, a better nutritional quality of gluten‐free bread can be obtained by the addition of chickpea and soybean. Gaps and needs in the use of legumes in gluten‐free breadmaking emerged and were gathered together to have a sound basis for future studies. The technological and nutritional potential of sourdough should be more extensively exploited. Moreover, in vitro and in vivo studies should be prompted to understand the health benefits of bread formulated with legumes. A holistic approach, interfacing food science, nutrition, and health might help to have, on the market, products with improved sensory properties and nutritional profile.     

Gluten‐free spaghetti made with chickpea,unripe plantain and maize flours: functional and chemical properties and starch digestibility

The development of gluten‐free spaghetti with a low amount of glycaemic carbohydrate was investigated. The goal of this study was to determine the chemical composition, cooking quality and starch digestibility of gluten‐free spaghetti elaborated with mixtures of chickpea, unripe plantain and maize flours. The gluten‐free spaghetti presented a higher protein, fat and ash content than the control semolina spaghetti. The solid loss among all the gluten‐free spaghetti was in the range of 10.04–10.91% and not significantly different from each other. These values were almost at the limit of acceptability to be considered as good cooking quality. Total starch in the gluten‐free spaghetti was lower than the control spaghetti. The lower available starch (AS) and higher resistant starch contents in the gluten‐free spaghetti were associated with their lower rate of hydrolysis and predicted glycaemic index. There is a potential for developing gluten‐free spaghetti with reduced amount of glycaemic carbohydrates from unconventional food ingredients such as chickpea, unripe plantain and maize flours.     

Gluten‐Free Snacks Using Plantain–Chickpea and Maize Blend: Chemical Composition,Starch Digestibility,and Predicted Glycemic Index

An increase in celiac consumers has caused an increasing interest to develop good quality gluten‐free food products with high nutritional value. Snack foods are consumed worldwide and have become a normal part of the eating habits of the celiac population making them a target to improve their nutritive value. Extrusion and deep‐frying of unripe plantain, chickpea, and maize flours blends produced gluten‐free snacks with high dietary fiber contents (13.7–18.2 g/100 g) and low predicted glycemic index (28 to 35). The gluten‐free snacks presented lower fat content (12.7 to 13.6 g/100 g) than those reported in similar commercial snacks. The snack with the highest unripe plantain flour showed higher slowly digestible starch (11.6 and 13.4 g/100 g) than its counterpart with the highest chickpea flour level (6 g/100 g). The overall acceptability of the gluten‐free snacks was similar to that chili‐flavored commercial snack. It was possible to develop gluten‐free snacks with high dietary fiber content and low predicted glycemic index with the blend of the 3 flours, and these gluten‐free snacks may also be useful as an alternative to reduce excess weight and obesity problems in the general population and celiac community.     

Use of selected sourdough strains of Lactobacillus for removing gluten and enhancing the nutritional properties of gluten-free bread

Forty-six strains of sourdough lactic acid bacteria were screened for proteolytic activity and acidification rate in gluten-free (GF) flours. The sourdough cultures consisted of Lactobacillus sanfranciscensis LS40 and LS41 and Lactobacillus plantarum CF1 and were selected and used for the manufacture of GF bread. Fermentation occurred in two steps: (i) long-time fermentation (16 h) and (ii) fast fermentation (1.5 h) using the previous fermented sourdough as inoculum (ca. 43%, wt/wt) with Saccharomyces cerevisiae (baker's yeast). GF bread started with baker's yeast alone was used as the control. Gluten was added to ingredients before fermentation to simulate contamination. Initial gluten concentration of 400 ppm was degraded to below 20 ppm only in the sourdough GF bread. Before baking, sourdough GF bread showed phytase activity ca. sixfold higher than that of GF bread started with baker's yeast alone. Atomic absorption spectrophotometric analysis revealed that the higher phytase activity resulted in an increased availability of free Ca2+, Zn2+, and Mg2+. The concentration of free amino acids also was the highest in sourdough GF bread. Sourdough GF bread had a higher specific volume and was less firm than GF bread started with baker's yeast alone. This study highlighted the use of selected sourdough cultures to eliminate risks of contamination by gluten and to enhance the nutritional properties of GF bread.     

Protein Characteristics that Affect the Quality of Vital Wheat Gluten to be Used in Baking: A Review

The use of vital wheat gluten in the baking industry and wheat flour mills aims to improve the rheological characteristics of flour considered unsuitable to obtain products such as sliced bread, French bread, high‐fiber breads, and other products that require strong flours. To improve characteristics such as flour strength, dough mixing tolerance, and bread volume, vital wheat gluten is added to flour at levels that can vary from 2% to 10% (flour basis), with 5% being a commonly used dosage. However, the vital wheat gluten commercialized in the market has few quality specifications, especially related to the characteristics of the proteins that constitute it and are responsible for the formation of the viscoelastic gluten network. Information on protein quality is important, because variations are observed in the technological quality of vital wheat gluten obtained from different sources, which could be associated to damage caused to proteins during the obtainment process. Several tests, either physical–chemical analyses, or rheological tests, are carried out to establish gluten quality; however, they are sometimes time‐consuming and costly. Although these tests give good answers to specify gluten quality, flour mills, and the baking industries require fast and simple tests to evaluate the uses and/or dosage of vital gluten addition to wheat flour. This review covers the concepts, uses, obtainment processes, and quality analysis of vital wheat gluten, as well as simple tests to help identify details about protein quality of commercial vital wheat gluten.     

Non-destructive characterization of pulse flours—A review

The consumption of plant-based proteins sourced from pulses is sustainable from the perspective of agriculture, environment, food security, and nutrition. Increased incorporation of high-quality pulse ingredients into foods such as pasta and baked goods is poised to produce refined food products to satisfy consumer demand. However, a better understanding of pulse milling processes is required to optimize the blending of pulse flours with wheat flour and other traditional ingredients. A thorough review of the state-of-the-art on pulse flour quality characterization reveals that research is required to elucidate the relationships between the micro- and nanoscale structures of these flours and their milling-dependent properties, such as hydration, starch and protein quality, components separation, and particle size distribution. With advances in synchrotron-enabled material characterization techniques, there exist a few options that have the potential to fill knowledge gaps. To this end, we conducted a comprehensive review of four high-resolution nondestructive techniques (i.e., scanning electron microscopy, synchrotron X-ray microtomography, synchrotron small-angle X-ray scattering, and Fourier-transformed infrared spectromicroscopy) and a comparison of their suitability for characterizing pulse flours. Our detailed synthesis of the literature concludes that a multimodal approach to fully characterize pulse flours will be vital to predicting their end-use suitability. A holistic characterization will help optimize and standardize the milling methods, pretreatments, and post-processing of pulse flours. Millers/processors will benefit by having a range of well-understood pulse flour fractions to incorporate into food formulations.     

Recent advances in the formulation of gluten-free cereal-based products

The replacement of gluten presents a major technological challenge, as it is an essential structure-building protein, which is necessary for formulating high quality cereal-based goods. Rising demands for gluten free products parallels the apparent or real increase in coeliac disease, or other allergic reactions/intolerances to gluten. This paper reviews the current prevalence of coeliac disease, and recent advances in the preparation of gluten-free products, using starches, hydrocolloids, gums and novel ingredients and processes.