Investigation of dielectric properties, total phenolic content and optimum formulation of microwave baked gluten-free cakes.

This study discusses the production of microwave baked gluten-free cakes formulated by mixing buckwheat flour and rice flour at different concentrations. Three different ratios of buckwheat flour to rice flour (20:80%, 30:70%, 40:60%) and two different gum types (xanthan and guar gum) with a white layer cake recipe were employed. The batters were baked in microwave oven at different microwave powers (540 W, 450 W, 360 W) for different baking times (3 min, 3.5 min, 4 min). The effect of microwave power, baking time and buckwheat flour concentration on weight loss, color, specific volume, porosity, total phenolic content and dielectric properties were investigated. The optimum microwave power, baking time and buckwheat flour concentration were found as 432.77 W, 3 min, 40% for guar gum added cakes and 360 W, 3.70 min and 29.23% for xanthan gum added ones. It was found that weight loss and color values of the cakes that were baked at the optimal conditions were less than those of control cakes. On the other hand, total phenolic content, specific volume, porosity, dielectric constant and dielectric loss factor values were higher for guar gum added cakes compared to control samples. In addition, it was observed that the cakes prepared with guar gum had similar pore size distribution with control cakes. As a conclusion of the study, it can be declared that surface color and specific volume problems of microwave baking could be solved by addition of guar gum to the formulation which also enables the production of functional, phenolic rich microwave baked cakes.

Dielectric properties, optimum formulation and microwave baking conditions of chickpea cakes.

The aim of this study was to correlate dielectric properties with quality parameters, and to optimize cake formulation and baking conditions by response surface methodology. Weight loss, color, specific volume, hardness and porosity were evaluated. The samples with different DATEM (0.4, 0.8 and 1.2%) and chickpea flour concentrations (30, 40 and 50%) were baked in microwave oven at different power (300, 350, 400 W) and baking times (2.50, 3.0, 3.50 min). It was found that microwave power showed significant effect on color, while baking time showed effect on weight loss, porosity, hardness, specific volume and dielectric properties. Emulsifier level affected porosity, specific volume and dielectric constant. Chickpea flour level affected porosity, color, hardness and dielectric properties of cakes. The optimum microwave power, baking time, DATEM level and chickpea flour level were found as 400 W, 2.84 min, 1.2% and 30%, respectively. The comparison between conventionally baked and the microwave baked cakes at optimum points showed that color difference, weight loss, specific volume and porosity values of microwave baked cakes were less than those of conventionally baked cakes, on the other hand, hardness values were higher. Moreover, a negative correlation between dielectric constant and porosity, and weight loss values were detected for microwave baked samples. A negative correlation between dielectric loss factor and porosity was observed. These correlations indicated that quality characteristics of a microwave baked cake sample can be assessed from dielectric properties. These correlations provides understanding on the behavior of food material during microwave processing.