Drying turmeric (Curcuma longa L.) using far‐Infrared radiation: Drying characteristics and process optimization

Abstract

This study investigated the turmeric drying characteristics and process parameters optimization for far‐infrared (FIR) radiation drying of turmeric. The initial moisture contents of the sliced wet turmeric samples were approximately 80 ± 0.12% (wb). The turmeric was exposed to 6.65, 5.97, 4.97, and 4.80 μm FIR radiation for 70, 30, 25, and 20 min, respectively. The moisture content and color (L*, a*, and b* values) of turmeric were measured during the experiment. The optimization experiments were conducted based on response surface methodology according to a central composite design with two independent variables: exposure time and FIR wavelength. The dependent variables considered were moisture content, curcumin content, energy consumption, and color‐changing index. The final moisture content and curcumin content were reduced with decreasing FIR radiation wavelength. FIR radiation drying of turmeric was observed to be a falling rate process. The optimal conditions were obtained with the FIR wavelength of 5.51 μm and exposure time of 21 min by applying the desirability function method. Under the optimal conditions, the predicted values of response variables, curcumin content, color‐changing index, energy consumption, and final moisture content were 3.26% (dry weight), 13.29, 2.51 kWh/g water, and 10.25% (wb). The desirability of 0.8157 under the optimal conditions further confirmed the validation of models. The results concluded that the FIR radiation could effectively apply for drying turmeric. Practical Applications The far‐infrared radiation can be applied for turmeric drying on an industrial scale. The drying rates and color‐changing index of turmeric increased with decreasing far‐infrared wavelength and increasing far‐infrared exposure time. Curcumin was reduced by increasing the far‐infrared wavelength and far‐infrared exposure time. The wavelength of 5.51 μm and exposure time of 21 min was the optimal conditions for FIR drying of turmeric. Therefore, the industry can achieve the optimum quality of turmeric within a shorter period of time by applying this technique.

Effect of ultrasonic far-infrared synergistic drying on the characteristics and qualities of wolfberry (Lycium barbarum L.)

“…In the drying process, the uniform temperature distribution is maintained, and the demand for airflow in the drying process is reduced. In recent years, infrared radiation has been successfully applied to the dehydration of various agricultural products, such as turmeric [6] , apple [7] , stevia [8] , and kiwifruit [9] . However, although far-infrared technology has significant effect on heat transfer in the drying process, it has little effect on promoting mass transfer because of its limitations.…”

Application of far‐infrared radiation for sun‐dried chili pepper (Capsicum annum L.): drying characteristics and color during roasting

“…The moisture content of chili pods and their components decreased continuously throughout the drying period and mainly showed a falling rate at each wavelength. The absence of a period of constant drying rate was reported previously in many IR drying studies, where only the falling rate period was present, such as for bean, 40 chili pods, 25 carrot, 41 dill leaves, 42 and turmeric 43 …”

“…The absence of a period of constant drying rate was reported previously in many IR drying studies, where only the falling rate period was present, such as for bean, 40 chili pods, 25 carrot, 41 dill leaves, 42 and turmeric. 43 The temperature increases with time during FIR in each experiment. Bhinder et al 44 stated that, in IR roasting, the material is exposed to IR that interacts, penetrates, and transfers thermal energy in the form of electromagnetic waves throughout the material uniformly.…”

Hybrid microwave with hot air drying of black‐gram ( Vigna mungo L) nuggets: Drying characteristics, modeling, and process optimization

“…Therefore, the response surface method technique has proven successful in optimizing the drying process parameters of different food products such as tomato (Obajemihi et al, 2021), puffed brown rice (Swarnakar et al, 2019), turmeric (Fernando et al, 2021), sweet potato (de Souza et al, 2021), etc.…”