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Fruits have a limited harvest season, and the amount of their waste is significant. Drying extends the shelf life of food, and the infrared dryer reduces the time and cost of the drying process. In this study, the effect of sonication at different powers and temperatures along with edible coating with xanthan and wild sage seed gums on the drying process of cornelian cherry by an infrared dryer was investigated.

Solutions of xanthan and wild sage seed gums were used for coating of fresh cornelian cherry. Xanthan gum powder (food grade) was purchased from FuFeng Co. (China). Wild sage seed gum was extracted and used in powder form after drying and grinding to prepare the gum solution. In this study, various concentration of gums solutions (xanthan and wild sage seed) were first prepared in a graduated glass beaker and placed in an ultrasonic bath (Backer vCLEAN1-L6, Iran). The fruits were immersed in the gum solutions (inside the beakers) and sonicated for 5 min (40 kH). Infrared dryer with an infrared radiation source (250 W, near-infrared (NIR), Noor Lamp Company, Iran) was used for drying samples. The distance of samples from the radiation lamp was 10 cm. After each pretreatment (sonication and coating), the samples were dried, until reaching a constant weight. The mass changes of samples were recorded using a Lutron GM-300p digital balance (Taiwan). The rehydration tests were conducted with a water bath (R.J42, Pars Azma Co., Iran). Dried samples were weighed and immersed for 30 minutes in distillated water in a 200 ml glass beaker at 50°C. Then, the extra moisture was drained for 30 s and the samples were re-weighed. The rehydration ratio values (%) of dried samples were determined as the ratio of the final weight of rehydrated samples over the dried samples weight × 100. The color of the cornelian cherry was calculated by determining the lightness (L*) and chromaticity (redness (a*) and yellowness (b*)), and was measured using a scanner (Hp Scanjet 300, China) and Image J software (V.1.42e, USA). The Folin-Ciocalteu (Folin-Ciocalteu's phenolics reagent, Sigma-Aldrich, USA) method was followed for measuring the total phenolics content of dried cornelian cherry. The absorbance of samples (765 nm, UV-VIS spectrophotometer, XD-7500, Lovibond, Germany) was compared with the Gallic acid standard curve. The results were expressed as mg GAE/g dry matter. Effect of applied power by the ultrasonic device at three levels of 0, 75, and 150 W and the effect of temperature at three levels of 20°C, 40°C, and 60°C on the rehydration and total color difference index of dried cornelian cherry were investigated. Also, the effect of coating with xanthan and wild sage seed gums on preserving phenolic compounds, antioxidant activity, and sensory properties of the product was evaluated.

The average drying time of uncoated cornelian cherry, coated with xanthan gum, and wild sage gum was 62 min, 48.7 min, and 48.4 min, respectively. The examined treatments in this research did not have a significant effect on rehydration change of the dried product. Ultrasonic pretreatment at both 75 and 150 W powers had a decreasing effect on the color changes, which indicates improvement of color and prevention of color change and decrease in desirability. The effect of coating on color changes was also investigated, and the amount of color changes in the uncoated, coated with xanthan gum and wild sage seed gum samples was equal to 26.71, 26.02, and 31.36, and there was no significant difference between them (p>0.05). Using wild sage seed gum preserved more of phenolic and antioxidant compounds. The total phenolics content of fresh cornelian cherry, and dried samples including market, without coating, coated with xanthan gum, and coated with wild sage seed gum was 23.0, 4.7, 0.8, 9.8, and 12.1 mg gallic acid/g, respectively. The market sample had a significant difference with other dried samples dried by infrared (p<0.05). The sample from the market had the least DPPH radical scavenging activity (p<0.05). The market sample scored as the lowest sensory evaluation and had a significant difference with all samples in all sensory attributes (p<0.05).

From the panelist’s point of view, the sample coated with wild sage seed gum was the best sample, and the highest score for sensory parameters and overall acceptance was associated with this sample.

Sour cherries (Prunus cerasus L.) are relatively diverse and broadly distributed around the world, being found in Asia, Europe, and North America. Sour cherries have unique anthocyanin content, and rich in phenolic compounds. The fruits are generally used for processing purposes, such as for production juice and jam. The fruits of sour cherries can also be frozen and dried. One of the best methods for the preservation of agricultural product is drying, which involves removing water from the manufactured goods. Dried sour cherries have a long shelf life and therefore may be a fine alternative to fresh fruit all year round. There are no reports on the effect of microwave pretreatment on the hot air drying kinetics of sour cherries in the literature. Hence, the purpose of this study was to estimate the impacts of microwave pretreatment on the total phenolics, drying time, mass transfer kinetic, effective moisture diffusivity, total color difference index, shrinkage and rehydration of sour cherry. In addition, the moisture ratio changes of sour cherry during drying were modeled.

Sour cherries were purchased from the market at Bahar, Hamedan Province, Iran. The average diameter of fresh sour cherries was 1.6 cm. In this study, the water content of fresh and dried sour cherries was calculated using an oven at 103°C for 5 h (Shimaz, Iran). In this research, the effect of microwave time on the drying time, effective moisture diffusivity coefficient and rehydration of sour cherries was investigated and drying kinetics were modeled. To apply the microwave pretreatment on the sour cherries, a microwave oven (Gplus, Model; GMW-M425S.MIS00, Goldiran Industries Co., Iran) was used under atmospheric pressure. In this work, the influence of the microwave pretreatment time at five levels of 0, 30, 60, 90, and 120 s (power=220W) on the cherries was examined. After taking out the treated sour cherries from microwave device, the samples were placed in the hot-air dryer (70°C) as a thin layers. The dehydration kinetics of sour cherries were explained using 7 simplified drying equations. Fick's second law of diffusion using spherical coordinates was used to calculate the moisture diffusivity of sour cherries at various hot-air drying conditions. The rehydration test was conducted with a water bath (R.J42, Pars Azma Co., Iran). Dried sour cherries were weighed and immersed for 30 min in distilled water in a 250 ml glass beaker at 50°C.

The results showed that microwave treatment led to an increase in moisture removal rate from the sour cherries, an increase in the effective moisture diffusivity coefficient, and, consequently, a decrease in drying time. By increasing the microwave time from 0 to 12 s, the average drying time of sour cherries in the hot-air dryer was decreased from 370 min to 250 min (p<0.05). The average effective moisture diffusivity coefficient calculated for the samples placed in the hot-air dryer was 4.25×10-10 m2/s. Increasing the microwave time from 0 to 120 s increased the average effective moisture diffusivity coefficient by 85%. The maximum amount of phenolic was related to the sample treated with microwave for 90 seconds. Microwave treatment time had no significant effect on the rehydration of dried sour cherries.

Kinetic modeling of weight changes of sour cherries during drying was carried out using models in the sources, followed the Page model was selected as the best model to predict moisture ratio changes under the selected experimental conditions. The mean values of sum of squares due to error, root mean square error, and r for all samples ranged from 0.001 to 0.007, 0.005 to 0.017, and 0.997 to 0.999, respectively. Generally, 120 s pre-treatment by microwave is the best condition for drying sour cherries.

Sour cherries (Prunus cerasus L.) are relatively diverse and broadly distributed around the world, being found in Asia, Europe, and North America. Sour cherries have unique anthocyanin content, and they are rich in phenolic compounds. The fruits are generally used for processing purposes, such as for juice and jam. The fruits of sour cherries can also be frozen and dried (Doymaz 2007; Šumić et al 2013). One of the best methods for the preservation of agricultural products is drying, which consists in removing water from the manufactured goods (Salehi 2023). Dried sour cherries have a long shelf life and therefore may be a fine alternative to fresh fruit all year round (Wojdyło et al 2014). The effect of alkali ethyl oleate solution on the drying time of sour cherry was studied by Doymaz (2007). In this study, the thin-layer drying of sour cherries was carried out under two air temperatures of 55°C and 65°C. Their results showed that the effective moisture diffusivity of sour cherries based on the analytical solution of Fick’s second law ranged from 4.75×10−10 to 1.03×10−9 m2/s. Ultrasound pre-treatment as a non-thermal food processing technology could be a better pre-treatment technique for food processing, due to its benefits which comprise energy saving, preservation of original freshness and nutritional contents, keeping bioactive compounds, the decline in processing duration, and cost. Ultrasound pre-treatment accelerates the mass transfer in dehydration and drying of fruit and vegetable slices mostly due to the breakdown of cells and the creation of microchannels (Awad et al. 2012; Ghorbani et al. 2013). In terms of cost, ultrasonic is less expensive than other technologies, and the main cost of operating a sonication system is electrical energy, making it more cost-effective and environmentally friendly than other methods (Jalilzadeh et al. 2018). We found no report on the effects of ultrasound pretreatment on the hot-air drying kinetics of sour cherry in the literature. Hence, the purpose of this study was to estimate the impacts of ultrasound pretreatment on the drying time, mass transfer kinetic, effective moisture diffusivity (Deff), and rehydration of sour cherry. In addition, the moisture ratio changes of sour cherry during drying were modeled.

Sour cherries were purchased from the market at Hamedan, Hamedan Province, Iran. The average diameter of fresh sour cherries was 1.6 cm. In this study, the water content of fresh and dried sour cherries was calculated using an oven at 103°C for 5 h (Shimaz, Iran). In this research, the effect of ultrasound time on the drying time, effective moisture diffusivity coefficient, and rehydration of sour cherries were investigated, and drying kinetics were modeled. To apply the sonication treatments on the sour cherries, a Backer vCLEAN1-L6 ultrasonic bath (Iran) was employed with a frequency of 40 kHz and a power of 150 watts. The tank of the device was filled with 6L of distilled water and, then, after the temperature of the water reached 25°C, the sour cherries were placed directly in the bath. To apply ultrasound pre-treatment, the sour cherries were placed inside the ultrasonic bath device for 0, 4, 8, and 12 minutes, and after leaving the device and removing extra moisture, the samples in thin layers were placed in the hot-air dryer (with a temperature of 70°C). The dehydration kinetics of sour cherries have been explained using 6 simplified drying equations. Fick's second law of diffusion using spherical coordinates was used to calculate the moisture diffusivity of sour cherries at various hot-air drying conditions. The rehydration tests were conducted with a water bath (R.J42, Pars Azma Co., Iran). Dried sour cherries were weighed and immersed for 30 min in distilled water in a 250 ml glass beaker at 50°C.

The results showed that sonication treatment, causes an increase in moisture removal rate from the sour cherries, an increase in the effective moisture diffusivity coefficient, and as a result, reduces the drying time. By increasing the sonication time from zero to 12 min, the average drying time of sour cherries in the hot-air dryer decreased from 465 min to 340 min. The average effective moisture diffusivity coefficient calculated for the samples placed in the hot-air dryer was equal to 3.86×10-10 m2/s. Increasing the sonication time from 0 to 12 minutes increased the average effective moisture diffusivity coefficient by 38%. The time of ultrasound treatment had no significant effects on the rehydration of dried sour cherries. Xu et al. (2022) reported that ultrasonic pretreatment changes the microstructure of pineapple slices, and the combination of ultrasonic and osmosis dehydration improves the effectiveness of the sonication, shortens the dehydration time, and produces a higher-quality product.

Kinetic modeling of sour cherries weight changes during drying was carried out by models in the sources, followed the Page model was selected as the best model to predict moisture ratio changes under the selected experimental conditions. Mean values of the sum of squares due to error, root mean square error, and r for all samples ranged from 0.003-0.010, 0.010-0.018, and 0.998-0.999, respectively. Generally, 12 minutes pre-treatment by ultrasound is the best condition for drying sour cherries.

The use of ultrasonic waves to change the structure of the gums leads to the modification and improvement of their functional characteristics and rheological properties. In this research, the effects of ultrasonic intensity and treatment time on apparent viscosity, consistency coefficient, and flow behavior index of different concentrations of xanthan gum were investigated and modeled. Genetic algorithm-artificial neural network method with three inputs (ultrasonic power, treatment time and gum concentration) and three outputs (viscosity, consistency coefficient, and flow behavior index) was used to model the process. The apparent viscosities of the xanthan gum control sample (untreated) at concentrations of 0.1, 0.15, and 0.2% were 21.0, 39.9, and 66.5 mPa.s, respectively. The results of this research showed that gum viscosity decreased with increasing intensity and duration of ultrasound application. Ultrasonic treatment for 20 min significantly reduced the apparent viscosity of xanthan gum from 39.9 to 23.2 mPa.s (p< 0.05). The genetic algorithm-artificial neural network modeling results showed that the network with 3-5-3 structure in a hidden layer and using the hyperbolic tangent activation function can predict the rheological parameters of xanthan gum with high correlation coefficient and low error value. Values of mean squared error (MSE), normalized mean squared error (NMSE), mean absolute error (MAE), and correlation coefficient (r) to predict the apparent viscosity of xanthan gum were 73.17, 0.20, 6.48, and 0.90, respectively. Based on the results of the sensitivity analysis test, ultrasonic treatment intensity was the most effective factor in changing the apparent viscosity, consistency coefficient, and flow behavior index of xanthan gum.

One of the recent uses of sonication is to change the composition and structural properties of hydrocolloids. This study aimed to examine the impacts of sonication at different intensities (0, 75, and 150 W) and time (0, 5, 10, 15, and 20 min) on the viscosity and rheological properties of sodium alginate solution. The results showed that the apparent viscosity of sodium alginate solution (control sample) decreased from 0.075 to 0.032 Pa.s with increasing shear rate from 12.2 to 134.5 s-1. Also, the apparent viscosity of sodium alginate solution decreased from 0.044 to 0.019 Pa.s with enhancing the sonication time from 0 to 20 min (shear rate=61 s-1, 150 W). Various rheological equations (Power law, Bingham, Herschel-Bulkley, Casson, and Vocadlo) were employed to fit the empirical values, and the results confirmed that the Power law model was the best fit to describe the flow behaviour of sodium alginate solution. The consistency coefficient of sodium alginate solution significantly decreased from 0.216 Pa.sn to 0.151 Pa.sn (p<0.05) with enhancing sonication time from 0 to 20 min. Furthermore, the consistency coefficient of sodium alginate solution decreased significantly (p<0.05) while the ultrasonic power enhanced. Flow behaviour index of sodium alginate solution enhanced significantly (p<0.05) while the intensity and duration of ultrasound treatment enhanced.

Due to their high moisture content, cherries have a very high rate of spoilage and require the use of some post-harvest treatments in order to be effectively preserved. Drying is one of these preservation methods. Drying time can be shortened by using ultrasonic waves as a pretreatment before drying agricultural products. The genetic algorithm–artificial neural network method has a high ability to find the optimal value of a complex objective function. In this study, the effect of sonication treatment for 0, 3, 6, and 9 minutes on drying time, weight changes, and rehydration of cherries was investigated. In the next step, this process was modeled by genetic algorithm–artificial neural network method with 2 inputs (drying time and ultrasonic pretreatment time) and 1 output (weight loss percentage). The results of this research showed that sonication for up to 3 min increased the rate of moisture removal from cherries and thus reduced drying time. 3-min treatment with ultrasound increased the rehydration of dried cherries; but as the treatment time increased to 6 min and 9 min, the amount of rehydration decreased. Genetic algorithm–artificial neural network modeling results showed that a network with a 1-4-2 structure in one hidden layer and using the hyperbolic tangent activation function can predict the weight loss percentage of cherries during drying with a high correlation coefficient and a low error value. According to the results of sensitivity analysis test, drying time was the most effective factor in changing the weight loss percentage of cherries during the drying process. In general, the best conditions for drying cherries are pretreatment with ultrasound for 3 minutes followed by drying the product with hot-air. Based on the modeling results, the genetic algorithm–artificial neural network method can also be used to predict the parameters of the cherry drying process.

In this research, the effect of ultrasound treatment at different powers and temperatures on the drying process of cornelian cherry by infrared dryer was investigated and modeled. The effect of the applied power by the ultrasonic device at three levels of 0, 75 and 150 W and the effect of the ultrasonic treatment temperature at three levels of 20, 40 and 60 °C on the mass transfer rate and the effective moisture diffusivity coefficient during the drying process of cornelian cherry were investigated. The results of this research showed that ultrasonic pretreatment before drying cornelian cherry by the infrared dryer, by creating microscopic channels on the product surface due to the cavitation phenomenon, makes it easier for moisture to exit from the product and thus reduces the drying time. By increasing the ultrasonic power from 0 to 150 W, the average drying time of cornelian cherry decreased from 73.2 minutes to 51.4 minutes. By increasing the treatment temperature from 20 to 60 °C, the average drying time of cornelian cherry decreased from 69.7 minutes to 55.7 minutes. The effect of power and time of ultrasound treatment on the effective moisture diffusivity coefficient changes of cornelian cherry was investigated and the results showed that with the increase in the power and temperature of the ultrasonic device, the values of this coefficient increase. By increasing the sonication power from 0 to 150 W, it was observed that the effective moisture diffusivity coefficient increased from 6.63×10-9 m2s-1 to 10.11×10-9 m2s-1. The average effective moisture diffusivity coefficient of cornelian cherry treated at temperatures of 20, 40 and 60 °C were 7.26×10-9 m2s-1, 8.10×10-9 m2s-1, and 9.45×10-9 m2s-1, respectively. In order to investigate the drying kinetics of cornelian cherry, mathematical models were fitted to the experimental data.