Drying of sliced tomato (Lycopersicon esculentumL.) by a novel halogen dryer: Effects of drying temperature on physical properties, drying kinetics, and energy consumption

Abstract

This study aimed to explore the impact of halogen drying temperature (60, 70, and 80°C) on drying kinetics and some sensory and physical properties of tomato slices. Also, the suitability of previously proposed models for predicting the drying process of tomato slices was assessed and compared with that of a newly proposed model using root mean square error, reduced chi‐square, and determination of coefficient. According to the results, increasing the drying temperature from 60 to 80°C reduced the drying time from 150 to 106 min but increased energy consumption. Experimental drying curves indicated only one falling drying rate period for the drying temperatures of 60 and 70°C, while two consecutive falling rate periods were observed for drying temperatures of 80°C due to the case‐hardening phenomenon. The highest sensory score was obtained for samples dried at 60°C. Also, the effective moisture diffusion varied between 7.96 × 10−9 and 1.07 × 10−8 m2/s. The color parameters (L*, a*, b*, a*/b*, and ∆E) of samples were significantly affected by drying temperature. The browning index and mass transfer coefficient increased significantly (p < .05) with the increase of the drying temperature. The results introduced halogen drying as a promising processing technology for drying tomato slices. Practical applications Drying, such as tomato slices drying, is one of the common process in the food industry. A novel drying technique, that is, halogen drying, was explored in the present study. This innovative process showed a good potential for upscaling, considering its ability in saving energy consumption, reducing drying time, and producing high‐quality products. Also, the effects of important process parameters, such as drying temperature, on the quality of the product were explained which can help with future commercial applications. Furthermore, the new mathematical models proposed in this study can be used by the industry to predict the quality parameters of the product and to achieve process automation.

A pilot‐scale rotary infrared dryer of shrimp (Metapenaeus affinis): Mathematical modeling and effect on physicochemical attributes

“…Moreover, moisture diffusion from the inner part of foods is toward controlling the drying rate (Al‐Hilphy et al, 2021). It can be seen from Figure 6 that the drying rate consisted of three parts of the falling rate period for all drying temperatures.…”

“…The results showed that the drying rate significantly ( p < .05) increased as drying temperature increased because of increasing evaporated water from shrimp to air drying with increasing drying temperature. Al‐Hilphy et al (2021) stated that the drying temperature significantly affects the drying rate. Murali et al (2021) dried shrimp by a solar dryer at 54°C, and it was found that the drying rate reduced from 0.7 to 0.05 kg/kg dm.…”

“…The image processing method was used to analyze the color characteristics of the dried shrimp. Images of fresh and dried shrimp were taken with a high‐resolution digital camera (8 megapixels) (IP67 Endoscope, Mileseey, China) under appropriate lighting as described in the literature (Al‐Hilphy et al, 2021). ImageJ software was used to obtain the picture color values ( L , a , and b ) and then corrected to L *, a *, and b * according to Yam and Papadakis (2004).…”

“…This clarified that the transfer of moisture in shrimp occurs by the process of diffusion. These results agreed with Murali et al (2021), who stated that only the falling rate period represented the drying process of shrimp dried by solar energy.Moreover, moisture diffusion from the inner part of foods is toward controlling the drying rate(Al-Hilphy et al, 2021). It can be seen from Figure6that the drying rate consisted of three parts of the falling rate period for all drying temperatures.…”

Suitability of thin-layer drying models for halogen lamp drying of sugarcane bagasse

“…Although hot air dryers are most commonly used for drying agricultural residue and lignocellulosic materials, their efficiency in the falling rate period of drying is lower than radiant dryers such as halogen lamps. This is because the temperature is directly (without any contact with the surrounding air) brought to the surface of materials under drying, resulting in an increase in the rate of heat transfer to the surface of solid materials (Sharma and Prasad 2001;Al-Hilphy et al 2021;Huang et al 2021). Du et al (2005) and Huang et al (2021) studied the drying process of wood strands and lignocellulosic biomass by microwave heating dryers and concluded that these dryers functioned more effectively than hot air dryers at moisture contents below the fiber saturation point (FSP) point.…”