Comparative Investigation of Drying and Quality Characteristics of Organic and Conventional Black Carrots Dried by Intermittent Microwave and Hot Air

Abstract

The quality of agricultural crops is influenced by growing conditions and post-harvest processes, including drying. Moreover, the total phenolic and total antioxidant content in the product's structure and composition can be either positively or negatively affected by the heat treatments applied during drying. Additionally, the specific growing conditions and methods of water removal can lead to the development of distinct drying characteristics. There was no study comparing the drying kinetics and quality parameters of organic (OBC) and conventional (CBC) black carrot in the literature studies. In this study were aimed that mathematically modelling the drying kinetics for OBC and CBC with IMW (150, 300, 450 W) and HA (60, 70, 80°C), determining their differences and evaluating the effects of methods on quality properties. The results showed that L* and ΔE values of the final products increased significantly by increasing the power and temperature levels applied during drying and the powder samples were lighter in color compared to the fresh samples. The total phenolic and total antioxidant capacity values were higher in fresh OBC samples compared to the conventional variety. This result shows that OBC is superior to the CBC in terms of higher total phenolic and total antioxidant content. The activation energy (Ea) values of OBC and CBC dried by IMW and HA were calculated as 8.41x10-3; 8.40x10-3 Wg-1 and 25.50; 19.72 kJ mol-1, respectively. The Logistic and Verma were the best fit models for describing IMW and HA drying kinetics, respectively. The samples obtained with IMW drying, which resulted in a shorter drying time, were more effect in terms of preserving and increasing the total phenolic and antioxidant content compared to dried samples with HA. The results showed that that the temperature/power levels applied to the products during the drying process, thus the drying times and the methods of removing moisture from the product are effective in the preservation of the total phenolic components.