The quality of gluten-free products and diet

Abstract

Background and aim: Celiac disease (CD) is an autoimmune disease sustained by an inappropriate response to gluten in genetic predisposed individuals. The only treatment for CD is a lifelong strict gluten-free (GF) diet. A GF diet is a combination of naturally occurring GF foods and cereal-based foods formulated with GF substitutes of wheat, barley and rye. The production of GF products with good technological quality and consumer acceptability is challenging for food manufacturers. Indeed, gluten determines the viscoelastic behavior of wheat-based doughs and other important rheological and sensory features of products. Over the years, various strategies have been proposed to overcome the lack of gluten. For instance, hydrocolloids are very effective in solving some of GF bread quality issues. However, besides technological and sensory aspects of GF products, the nutritional quality should deeply be explored. Some population-based studies have pointed out several dietary imbalances among treated individuals with CD. Causes of such dietary imbalances in individuals with CD can be multiple. For instance, the focus on gluten exclusion and the several restrictions imposed by the GF diet. In the previous years, different studies have been dealing with GF products and diet. However, there are some open questions that deserve attention. In this view, the aims of this thesis were: i) to propose a simple tool to describe the nutritional profile of packaged GF bakery products in the perspective of leading their nutritional enrichment and comparing their nutritional quality to that of the gluten-containing (GC) counterparts; ii) to deepen the functional relationship between HPMC and hydration in GF bread making; iii) to address the role of Chia seeds and/or exuded mucilage as potential thickening agent and ingredient for nutritional enrichment in production of GF pasta, with similar characteristics to wheat pasta; iv) to study the dietary habits of a group of Italian individuals with CD with the aim of evaluating their adherence to a food pattern recognized for its protective role on the risk of major non-communicable disease. Methods: i) The nutritional quality of the GF bakery products was evaluated with a score-based method, which combined information from the nutritional facts and the presence/absence of some nutritionally relevant ingredients in the product formulation. ii) The synergic role of HPMC and hydration in influencing the dough consistency and the textural features of GF bread was analyzed in a multilevel factorial model. Rheological parameters from GF dough and bread were collected. iii) Chia seeds and/or the exuded mucilage were added to a commercial GF pasta formulation. The cooking analysis of pasta was performed together with the characterization of the proximate composition, the in-vitro carbohydrate digestibility and the content of phenolic compounds. iv) A group of individuals with CD from the northern Italy was enrolled to measure the adherence of their dietary habits to a MD. The Italian Mediterranean Index was used to score their dietary habits. Results: Regarding the GF bakery products and diet, our nutritional evaluation pointed out interesting findings. On one hand, the nutritional quality of GF bakery products was low according to the developed score. Interestingly, such a low quality was almost similar to that of the GC counterparts. In GF bread making, hydration was a major player in defining the consistency of a GF dough. However, the proper selection of HPMC, relying on its viscosity, may help to obtain good technological features of GF dough and bread. In GF pasta, both Chia seeds flour and exuded mucilage were useful to obtain a product with similar cooking and texture characteristics to those of wheat pasta. Furthermore, compared to a traditional commercial GF pasta, the inclusion of Chia seeds or mucilage raised the content of protein, dietary fibers and phenolic compounds. On the other hand, the dietary habits of individuals with CD were far from MD pattern; they mainly had a high consumption of meat, processed meat and potatoes and a low intake of fruit and vegetables. Interestingly, such a low adherence to a MD was even lower than that of a group of healthy participants. Conclusion: The quality of GF bread and pasta in terms of technological and nutritional characteristics can be ameliorated by the proper selection of HPMC and the inclusion of ingredients such as Chia seed or mucilage. However, GF products represent only a portion of food items in a GF diet. Accordingly, to improve the overall quality of a GF diet, dietary choices of individuals with CD should be better addressed towards a Mediterranean like pattern by healthcare professionals during the nutritional counseling.