Optimization of Baking of Rice Cakes

Celiac disease, which is due to the sensitivity to prolamin part of gluten, affects the small intestine. Patients who have this disease must follow a lifelong gluten-free diet. Gluten is the main structure-forming protein and is responsible for the elastic properties of the dough. In this respect, gluten replacement in designing gluten-free products is a challenging issue for food scientists and technologists. Rice with its low level of gluten, low levels of sodium, protein, fat, fiber and a high amount of easily digested carbohydrates, is one of the most convenient cereal in designing such food gluten-free products. However, some food additives such as starches, gums, hydrocolloids, and dairy products are required to be used for obtaining the good quality characteristics such as high volume, desired texture, color, and crumb structure.

 

The ability to control the rheological characteristics of aqueous systems makes gums important ingredients in food systems. Moreover, gums affect the stabilization of the emulsions, help to suspend particles, control crystallization, and inhibit syneresis (Lucca and Tepper 1994). Xanthan and guar gum are among the group of gums frequently included in food formulations to improve the mouth feel and change the rheological properties. When used together, a synergistic interaction occurs between xanthan and guar gum, and in the study of Casas et al. (2000), the mixtures of xanthan and guar gum provided higher viscosity than when each gum was used individually. Until the cake structure is set, emulsifiers have the ability of providing the necessary aeration and gas bubble stability during the process. Their function of reducing interfacial tension between oil and water droplets facilitates the disruption of oil droplets (Sahi and Alava 2003). In the study of Seyhun et al. (2003), using different emulsifier and gum types helped to retard staling of microwave-baked cakes effectively

 

Although microwave has the advantages of reducing the time and the energy during processing, it has disadvantages such as high moisture loss, unacceptable texture, and rapid staling. Moreover, browning reaction that is desirable for baked products does not occur because the surface temperature of dough or batter is not high enough to promote browning and crust formation. Microwaves can be combined by halogen lamp heating, as halogen lamp heating provides near-infrared radiation, and this radiation can be focused at the surface of the product. Therefore, required surface temperature for browning reactions can be obtained. Infrared–microwave combination oven has recently been used in cake and bread baking (Demirekler et al. 2004; Keskin et al. 2004; Sevimli et al. 2005). Response surface methodology (RSM), which is a collection of statistical and mathematical techniques, is a useful tool for development, improvement, and optimization of processes. It is used to examine the relationship between one or more response variables and a set of quantitative experimental variables or factors.

 

Many researchers have used this method in optimization of the bakery products. In the study of Sanchez et al. (2002), the proportions of cornstarch, cassava starch, and rice flour were optimized for production of gluten-free bread to maximize specific volume, crumb-grain score and bread score. In another study, RSM was used to optimize gluten-free bread fortified with soy flour and dry milk (Sanchez et al. 2004). Toufeili et al. (1994) studied the effects of methylcellulose, egg albumen, and gum arabic on the sensory properties of gluten-free pocket-type flat bread by using RSM. Although there are many studies in which RSM was used as an optimization tool for bakery products, there is no study about the optimization of the baking of a gluten-free rice cake in the literature. Therefore, the objective of this study was to optimize the infrared–microwave combination baking condition and formulation of gluten-free rice cakes by RSM. In addition, the effects of different gums on the quality of cakes were compared.