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Whole Grains and Health


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of sourdough processing to reduce starch digestibility is assumed to be mainly due to formation of organic acids, especially lactic acid, during fermentation (Liljeberg et al. 1995).

      Specific modifications in baked product texture can be achieved by development of new sourdough cultures, and by optimizing acidity and interactions with grain components. As reported by Katina et al. (2005), the changes in dough structure over time can not only be detected by small deformation viscoelastic measurements, but also by confocal laser‐scanning microscopy. The protein fraction of the gluten‐free sourdough is degraded over time, although this process is more obvious in wheat sourdough (Clarke et al. 2004). However, the addition of sourdough to gluten‐free batters does lead to an improvement of the gluten‐free‐bread (Katina et al. 2005).

       1.7.3 Cakes

      Cakes are characterized by high levels of sugar and fat in the formula. Since they also contain relatively high levels of water, the molar sugar concentration is not high enough to prevent starch gelatinization during baking. Because of that, cakes set when baked, giving a light product. The presence of α‐crystalline emulsifiers increases the incorporation of air and the batter volume (Richardson et al. 2002). During conventional baking, cake batter undergoes structural transformations, including starch gelatinization, protein denaturation, volume increase, liberation of carbon dioxide from leavening agents, water evaporation, crust formation and non‐enzymatic browning. Sucrose regulates starch gelatinization and protein denaturation during baking, causing a shift towards higher temperature values (Kim and Walker 1992). Partial or total substitution of sucrose has been studied using sorbitol, wheat starch and inulin (Baeva et al. 2003; Rodríguez‐García et al. 2014). However, the replacement of sucrose in sponge cake batters with other water‐retaining agents may affect the physical and chemical transformations in the sponge cake system (Rodríguez‐García et al. 2014).

      Rice flour, which does not contain gluten, is one of the alternatives to wheat flour in order to obtain gluten‐free cereal products. However, due to its low gas retention capacity, rice products have some quality problems such as low volume, poor texture, color and crumb structure. Gums such as xanthan, guar, κ‐carrageenan can be added to gluten‐free cake formulation in order to emulate the viscoelastic properties of glutenin. Different effects on the porosity are obtained depending on the gum type (Turabi et al. 2010).

       1.7.4 Pasta

      Two important transformations in the main components of durum wheat pasta take place during cooking: gluten polymerization and starch gelatinization. The competition of both components for water determines the final texture properties of the product (Fuad and Prabhasankar 2010). Microscopy techniques such as scanning electron microscopy and light microscopy of stained sections have helped to increase knowledge regarding the induced structural changes of pasta during cooking (Heneen and Brismar 2003). There is a moisture distribution gradient from the surface to the center due to the penetration of water and the progress of starch gelatinization. This moisture gradient is essential for the texture properties of pasta. In this way, the ideal texture of pasta, known as “al dente” is characterized by a soft outer region and a very thin hard core (Sekiyama et al. 2012). Pasta is usually made from durum wheat semolina and is a good source of low glycaemic index carbohydrate (Brennan 2008). Bran and germ particles in semolina produce a less homogeneous mixture and the particles can physically interfere with gluten development (Manthey and Schorno 2002). For this reason, bran and germ, commonly referred to as pollard, are largely removed during milling of durum wheat. However, nutritionally‐enriched pasta is also available commercially, prepared using wholemeal, semolina/flour or ground whole‐wheat. Although negative effects in the cooking and sensory properties of whole‐wheat or bran enriched pasta have been frequently reported, spaghetti dried at high temperature can be prepared with pollard, with 10% substitution of semolina, causing minimal impact on sensory and technological properties (Aravind et al. 2012). High molecular weight inulin can also be incorporated with minimal effect on the technological and sensory properties below 20% incorporation (Aravind et al. 2012b).

Photos depict the representative cross-sections of 10-min cooked spaghetti made of 100-percent fine durum wheat semolina and durum wholegrain flour. A: Bright field light micrographs at high magnification from three regions; B–D: Bright field light micrographs (B), polarized light micrographs (C), and T2 maps (D) of cross-sections at lower magnification.

      (Source: (B) and (D): Modified from Steglich et al. 2014).

      Crispbread, which traditionally has been elaborated with rye flour, have a continuous starch network which encapsulates the protein, due to the