# Nutritional and Functional Properties of Gluten-Free Flours
## 1 Introduction  
Coeliac disease or gluten-related disorders including, wheat allergy and non-celiac gluten sensitivity cause major health problems for people when ingesting small amount of gluten [1]. In addition to people who are forced to consume gluten-free products, the demand for these products has also increased for people who want to follow a healthy diet. In this sense, it is necessary to expand and diversify the food industry both in terms of progress in ingredients and formulations, and in the production of functional foods [2]. Because coeliac people have various nutrient deficiencies, there are many challenges in the development of gluten-free products [3, 4]. In addition to nutrient deficiencies, other issues make gluten products difficult to replace. For example, gluten-free dough is more difficult to handle due to a lack of cohesiveness, elasticity, and baking quality [5, 6]. In general, gluten-free products are characterized by high starch content, low fiber content, short shelf life or texture issues, like increased bread crump hardness [7]. Within this aim, more and more researches are being conducted to find formulations between different gluten-free flours and ingredients to obtain products that are similar to wheat-containing products. Rice is the most used cereal flour for gluten-free products development [8]. Rice has unique nutritional, hypoallergenic, colorless, and bland taste properties and a low level of prolamin. An alternative to rice is brown rice (unpolished rice), which contains many nutritional and bioactive components, including fiber, amino acids, minerals, and phenolic compounds [9]. Despite the many qualities of rice flour, it was necessary to expand the raw materials used for the development of gluten-free products to diversify the product range and to enrich the nutrient content. Thus, a long list of raw materials was used in various studies to develop the gluten-free sector as much as possible. Among them arecereals (maize, sorghum), whole grains (brown rice, millet, teff, oatmeal), pseudo-cereals (amaranth, quinoa, buckwheat), legumes (pea, lentilis, soybean, chickpea, gram), seeds (flax seeds, pumpkin seeds), nuts (almond, walnut, peanuts), tuberous rhizomes (tiger nut, jerusalem artichokes), and other types of raw materials (plantain, coconut) [3, 10]. [PERSON] et al. [11] showed that whole grains flours had higher fiber content compared to wheat flour. In addition, the protein content is higher in case of teff flour and lower for oat flour, but oat protein is superior to wheat protein due to its higher lysine content. Pseudo-cereals are a good alternative to wheat flour too because they are an important source of minerals (calcium, iron, and zinc), vitamins, and phytochemicals (saponins, polyphenols, phytosterols, phytosteroids and betalains), which present a real potential health benefit [12]. Legumes flours are usually used in gluten-free products due to their nutritionally properties. All of them are an important source of nutrients such as proteins, complex carbohydrates, fibers, micronutrients, and antioxidant compounds [13]. Chickpea is a legume rich in protein and has good emulsifying properties bringing an improvement in the gluten-free bread volume [14]. Chickpea flour was used in combination with tiger nut flour as an alternative to emulsifier and shortening in gluten-free bread. The effect of reducing or eliminating the shortening or emulsifier was due to the interaction between chickpea protein and tiger nut fat [14]. Tiger nut is a tuber rich in carbohydrates, lipids, and fiber; therefore, tiger nut flour was used in bakery products as well as for gluten-free bread with good baking and nutritional characteristics [15]. Another legume category is represented by Bengal gram, which is a pulse crop that contains approximately 17-22% protein, 6.48% fat, 3.82% crude fiber, and 50% carbohydrates [16]. Over the last few years, the use of plantain and other varieties of banana has increased around the world.