Effect of intermittent microwave convective drying on the phytochemicals in fruits

Abstract

The energy efficiency of the process and quality of dried product are two key factors in food drying. Global energy crisis and demand for quality dried food further challenge researchers to explore innovative techniques in food drying to address these issues. Intermittent microwave convective drying (IMCD) is an advanced drying process to reduce energy consumption and drying time. However, impact of this method on product quality has not been properly investigated. Particularly, experimental studies in product quality in terms of phytochemical compounds in IMCD is lacking. Therefore, the aim of this paper is to investigate the changes of phytochemical compounds in food material during IMCD. Quality attributes of dried samples were investigated in terms of volatile compounds, total phenolic content (TPC) and total flavonoid content (TFC). The experimental results showed that TPC at 50˚C, 60˚C and 70˚C were 19.77, 21.05 and 22.39mg GAE/g dw respectively, while the TFC at 50˚C, 60˚C and 70˚C were 1.08, 1.13 and 1.24mg QUE/g dw respectively. The Analysis of variance using response surface method (RSM) indicated a significant response to TPC and TFC at different temperatures.