Optimization of microwave frying of osmotically dehydrated potato slices by using response surface methodology

Microwave frying of osmotically dehydrated potatoes was optimized by using response surface methodology. Osmotic dehydration was applied prior to microwave frying in order to reduce oil uptake and to evaluate the effect of osmotic dehydration on quality of microwave fried potatoes. Moisture content, oil content, hardness and color of the fried potatoes were used as quality parameters. Microwave power level (400, 550, 700 W), frying time (1.5, 2.0, 2.5 min) and osmotic dehydration time (15, 30, 45 min) were the independent variables in the study. Osmotic dehydration treatment was conducted using 20% (w/w) sodium chloride solution at 30 °C. Moisture content of the fried potatoes decreased whereas oil content, hardness and ΔE value of potatoes increased with increasing frying time and microwave power level. The increase in osmotic dehydration time reduced moisture content and oil content and increased hardness of fried potatoes. The optimum condition was found as frying at 400 W microwave power level for 1.5 min after 39 min of osmotic dehydration time.     

Investigation of dielectric properties of different cake formulations during microwave and infrared-microwave combination baking

ABSTRACT:  Dielectric properties can be used to understand the behavior of food materials during microwave processing. Dielectric properties influence the level of interaction between food and high frequency electromagnetic energy. Dielectric properties are, therefore, important in the design of foods intended for microwave preparation. In this study, it was aimed to determine the variation of dielectric properties of different cake formulations during baking in microwave and infrared–microwave combination oven. In addition, the effects of formulation and temperature on dielectric properties of cake batter were examined. Dielectric constant and loss factor of cake samples were shown to be dependent on formulation, baking time, and temperature. The increase in baking time and temperature decreased dielectric constant and loss factor of all formulations. Fat content was shown to increase dielectric constant and loss factor of cakes.     

Effect of Ultrasound-Assisted Osmotic Dehydration as a Pretreatment on Deep Fat Frying of Potatoes

The objective of this study was to investigate the possibility of using ultrasound-assisted osmotic dehydration (UAOD) as a pretreatment prior to frying and to study its effects on the quality of fried potatoes. The quality parameters, moisture content, oil uptake, color, texture, and microstructure of fried potatoes, were chosen. Quality of fried potatoes treated with UAOD was also compared with the ones treated with osmotic dehydration (OD). Potato slabs (40 × 40 × 7 mm) were pretreated with different osmotic solutions (15 % sodium chloride and 15 % sodium chloride/50 % sucrose solutions) at different temperatures (25, 45, and 65 °C) with and without ultrasonic waves for different treatment times. The pretreatment conditions which are OD for 90 min and UAOD for 30 min using 15 % sodium chloride/50 % sucrose solution were applied prior to frying at 170 °C for 2, 4, and 6 min. UAOD reduced the oil content of fried potatoes by 12.5 % (db) as compared to untreated fried potatoes at the end of frying. There was no significant difference between OD and UAOD in reduction of oil uptake in fried potatoes. However, UAOD was found to have the advantage of improving the color of French fries. In addition, it shortened the pretreatment time of OD by about 67 %. Cell structure of fried potato was damaged in the presence of pretreatments of OD and UAOD.     

Optimisation of formulations and infrared–microwave combination baking conditions of chestnut–rice breads

The main objective of this study was to design gluten‐free breads containing chestnut and rice flour and xanthan–guar gum blend to be baked in infrared–microwave combination oven. Response surface methodology (RSM) was used to optimise gluten‐free bread formulations and processing conditions. Weight loss, firmness, specific volume and colour change of the breads were determined. Rice flour mixed with different proportions of chestnut flour and different emulsifier contents were used to prepare breads. The gluten‐free formulations were baked using different upper halogen lamp powers, microwave powers and baking time which were varied from 40% to 80%, 30% to 70% and 9 to 17 min, respectively. Gluten‐free breads and wheat breads baked in conventional oven were used for comparison. Breads containing 46.5% chestnut flour and 0.62% emulsifier and baked using 40% infrared and 30% microwave power for 9 min had statistically comparable quality with conventionally baked ones.     

Optimization of halogen lamp–microwave combination baking of cakes: a response surface methodology study

The main objective of this study was to optimize processing conditions during halogen lamp–microwave combination baking of cake by using response surface methodology. The independent variables were the power of the upper halogen lamp (50, 60, and 70%), the power of the lower halogen lamp (50, 60, and 70%), the power of the microwaves (30, 40, and 50%), and the baking time (4, 5, and 6 min). Weight loss, specific volume, color, and the texture profile of the cakes were determined. The upper halogen lamp power, the microwave power, and the baking time were found to have a significant effect on the weight loss, the specific volume, and the firmness of the cakes. Cakes baked for 5 min at 60% upper halogen lamp power, 70% lower halogen lamp power, and 30% microwave power had quality comparable with conventionally baked ones, except for color. By the usage of a halogen lamp–microwave combination oven it was possible to obtain high-quality cakes by reducing the conventional baking time by about 79%.     

Acrylamide formation in different batter formulations during microwave frying

Acrylamide, a probable human carcinogen, is found to be formed in a wide range of fried foods. In this study, the effects of microwave frying on acrylamide formation in the coating part of chicken were investigated. It was also aimed to determine the effects of various flour types (soy, chickpea and rice flour) in batter formulations on the acrylamide formation and on the color of fried chicken. Usage of all flour types except soy flour resulted in approximately the same moisture content and color development after 1.5 min of microwave frying. Acrylamide contents of batter parts of 1.5 min microwave fried samples having different flours were similar. Microwave frying provided lower acrylamide content and lighter color as compared to those fried conventionally for 5 min for all types of flours. This reduction in acrylamide level was the highest (34.5%) for rice flour containing batter.     

Utilization of Mixolab<Superscript>®</Superscript> to predict the suitability of flours in terms of cake quality

The objective of this study was to determine the possibility of using Mixolab^® to predict the cake baking quality of different wheat flours. Mixolab^® data were also compared with various flour quality characteristics. The correlations between Alveoconsistograph data and the cake quality characteristics were not significant. Therefore, Alveoconsistograph test does not seem to be useful to predict the cake quality of the flour samples. Mixolab^® characteristics C2, C3, C4 and C5 were found to be significantly correlated with volume index while C5 was correlated with hardness of cakes. The parameters C2 to C5 represent the end point of the corresponding mixing stages. The flour samples which gave higher cake hardness values had higher C5 values and the samples with lower cake volumes had higher C2, C3, C4 and C5 values. It seems to be possible to estimate the texture and volume of cakes by these values. Therefore, Mixolab^® seems to be a useful tool to predict the cake making quality of flour samples.