Quantifying of the Best Model for Prediction of Greenhouse Gas Emission, Quality, and Thermal Property Values during Drying Using RSM (Case Study: Carrot)

Abstract

The aim of this study is to use the response surface methodology (RSM) to mathematically model the response parameters and emission of greenhouse gases (GHG) and optimize the drying variables for a carrot dried with the microwave method using various pretreatments. To this end, the influence of the drying parameters (independent), such as microwave power and slice thickness dried by two pretreatments of ultrasonication at 30 °C for 10 min and blanching at 70 ℃ for 2 min, was explored on the dependent (response) parameters including the thermal properties (drying time, effective moisture diffusion coefficient (Deff), specific energy consumption, energy efficiency, quality features (color changes and shrinkage), and GHG emission (including CO2 and NOx). It should be mentioned that the emission of GHG was determined based on the energy consumption of various types of power plants such as the gas turbine steam power turbine, and combined cycle turbines using various fuels such as natural gas, heavy oil, and gas oil. The results indicated that the ultrasonication and blanching pretreatments can decrement the drying time (linearly), energy consumption (linearly or quadratically), shrinkage(quadratically), and color changes(quadratically) and enhance the Deff (linearly) and energy efficiency (linearly or quadratically) in all samples with R2 > 0.86. Moreover, the shortest drying time (42 min), lowest SEC (9.51 MJ/kg), and GHG emission ((4279.74 g CO2 in the combined cycle turbines plant, and 18.16 g NOX in the gas turbine plant) with natural gas for both plants) were recorded for the samples pretreated with blanching while the lowest color changes (13.69) and shrinkage (21.29) were observed in the ultrasonicated samples. Based on the optimization results, a microwave power of 300 W and steam power turbine of 2 mm were the best variables with a desirability of about 80% which resulted in the highest-quality products at the lowest GHG emission.

Qualitative, energy and environmental aspects of microwave drying of pre-treated apple slices

“…The DT of ultrasonicated apple samples decreases as compared to control samples due to the formation of more microscopic channels resulting from the cavitation phenomenon 60 . The findings of this research are in agreement with the reports published by other researchers for drying potatoes 61 , carrot 24 , and Tremella fuciformis 62 under microwave drying with ultrasound pretreatment.…”

“…Seyfi et al 33 showed that increasing the thickness of Aloe vera gel increases GHG emission for different drying methods due to the increase in drying time. Taghinezhad et al 24 and Kaveh et al 81 also obtained similar results for drying carrots and pear in different thicknesses, respectively.…”

“…As water removal from the cell increases the stress from the liquid on the cell wall during the drying process, as a result, it will lead to the shrinkage of the material. The ultrasound pretreatment, however, will reduce the stress on the apple tissue, hence, decreasing the shrinkage 24 .…”

“…In food processing, ultrasound causes changes in textural, rheological, physical, chemical and functional properties 19 . Several studies have also dried various food products using ultrasound pretreatment for Inula viscosa (L.) 17 , pumpkin seeds 20 , longan 21 , apple 22 , celery 23 , carrot 24 , and kiwifruit 25 . The results showed that pretreatments with different drying methods can be applied to decrease and increase the DT and the efficiency, respectively while preserving the final sample quality.…”

Multi-Step Design Optimization for the Improvement of an Outer-Rotor Brushless Direct Current Motor

“…These experiments are designed to systematically vary critical factors to understand how changes in these factors affect the outcomes or responses. The design often includes central composite design (CCD), Box-Behnken design (BBD), or factorial design as the selected design, and the workflow of the RSM is shown in Figure 8 [11,12,22].…”