Abstract
This study aimed to investigate the effect of different drying methods on the drying kinetic, total bioactive content, in-vitro bioaccessibility of bioactive compounds, and color and microstructural properties of pomegranate arils. Drying methods significantly affected all selected parameters of dried pomegranate arils (P<0.05). Freeze-drying (FD) showed higher bioactive compounds, lower shrinkage, and better color quality than those of other samples. Ultrasound-assisted vacuum drying (UAVD) showed lower drying times, lower shrinkage, and higher bioactive compounds than vacuum drying (VD) and hot air drying (HAD). The ABTS, CUPRAC, and DPPH results were 34.53-63.71 μmol TE/g, 29.70-61.60 μmol TE/g and 64.82-93.69% DPPH radical scavenging activity, respectively. Also, the highest values of antioxidant capacity for all methods were obtained from the samples dried with FD followed by UAVD, VD, and HAD. The recovery of TPC in dried and fresh samples changed from 2.58% (fresh pomegranate) to 10.32% (vacuum-dried pomegranate). The recovery of TPC for freeze-dried samples (2.62%) was closest to the fresh ones and VD showed the highest TPC recovery. This study suggested that UAVD and VD should be used as alternative methods to HAD due to higher bioactive compounds retention, better color and surface quality, and higher recovery of bioactive compounds.
Highlights
Pomegranate (Punica granatum L.) is a tropical-subtropical fruit that grows in many world regions such as the USA, Anatolia, Mesopotamia, India, and Mediterranean countries and is known almost all over the world
While moisture loss was observed at the beginning, there was a decrease in the moisture transfer rate towards the end of the drying process
The decrease in moisture transfer rate at the end of the drying process can be explained by the fact that the constant drying period is replaced by the diffusion drying period
Summary
Pomegranate (Punica granatum L.) is a tropical-subtropical fruit that grows in many world regions such as the USA, Anatolia, Mesopotamia, India, and Mediterranean countries and is known almost all over the world. Due to its low-temperature processing, FD resulted in quality products in sensory, microstructural, and bioactive properties in different food products (Chen et al, 2020; Wojdyło et al, 2016). Despite these advantages of the FD process, the high cost of the FD process restricts the use of FD (Huang et al, 2009) in a wide range of foods. There is a need to develop alternative methods to HAD and FD that are easy to use, have low operating costs, and provide quality products
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