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Coating of fruits with edible gums increases the appearance quality, improves the color and reduces their shrinkage at the end of the drying process. In this study, Xanthan and Balangu gums were used to coating of apricot slices during drying in the infrared system and the drying kinetics of the samples were modeled. In this study, apricots were divided into three groups: control (without coating), coated with xanthan gum and coated with balangu seed gum, and then the effect of infrared lamp power (150, 250 and 375 W) and distance of samples from lamps ( 5, 7.5 and 10 cm) on the drying time of the samples were investigated. The concentration of used gum was 0.6% (w/w) and the thickness of apricot slices was 0.5 cm. The results of drying the apricot samples by infrared method showed that with increase in lamps power and decrease in samples distance from the heat source, the drying time decreases. Coating pretreatment increased the drying time of apricots and the drying time of samples coated with balangu seed gum was longer. The average drying time of the control samples, coated with xanthan and balangu gum was 73.11 min, 81.04 min and 83.74 min, respectively. This process was modeled by an artificial neural network with 3 inputs (type of coating, radiation lamp power and lamp distance) and 1 output (drying time). The results of artificial neural network modeling showed that the network with 7 neurons in a hidden layer and using the sigmoid activation function can predict the drying time of coated apricots using an infrared dryer (r=0.974).

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Edible coatings application to the food prior to drying by infrared system is another potential pretreatment to drying. Edible coatings are thin layers of an edible material applied to the surface of the food and creating a selective barrier to the gas transport. The aim of this study was to investigate the color and area changes of coated apricot slices with xanthan and balangu seeds gums during drying in the infrared system. In this study, apricot slices in cylinder form with a thickness of 0.5 cm were coated using xanthan and balangu seeds gum (concentration of 0.6%) and then placed in an infrared dryer and the effect of radiation power (150, 250 and 375 W) on the appearance characteristics were examined. To examine the color and area changes of the samples, samples image were taken continuously during drying time. Color indexes including brightness (L*), redness (a*), yellowness (b*) and color changes (ΔE) as well as changes in the samples area during drying time were calculated. The calculated L* index for the drying process of apricot samples showed that the coated samples were brighter in terms of brightness and the coated apricots with balangu seed gum had higher L* values. In terms of color change index (ΔE), coated apricots with balangu seed gum showed the lowest color changes during drying time and the average values of ΔE for the control sample, coated with xanthan gum and coated with balangu seed gum were equal to 21.30, 16.89 and 13.92, respectively. For modeling the color change index, the quadratic model had less error than the power model. The results showed that the coating with balangu seed gum maintained the appearance of the dried product.