Dried Figs Quality Improvement and Process Energy Savings by Combinatory Application of Osmotic Pretreatment and Conventional Air Drying

Varvara Andreou; Ioanna Thanou; Marianna Giannoglou; Maria C Giannakourou; George Katsaros

doi:10.3390/foods10081846

Dried Figs Quality Improvement and Process Energy Savings by Combinatory Application of Osmotic Pretreatment and Conventional Air Drying

Foods. 2021 Aug 10;10(8):1846. doi: 10.3390/foods10081846.

Authors

Varvara Andreou¹, Ioanna Thanou², Marianna Giannoglou¹, Maria C Giannakourou², George Katsaros^{1

3}

Affiliations

¹ Institute of Technology of Agricultural Products, Hellenic Agricultural Organization-DEMETER, Lykovrissi, 14123 Attica, Greece.
² Department of Food Science and Technology, University of West Attica, Egaleo, 12243 Attica, Greece.
³ Institute of Technology of Agricultural Products, ELGO-DEMETER, Sof. Venizelou 1, Str., 14123 Lykovrissi, Greece.

Abstract

This study concerns the implementation of osmotic dehydration (OD) as a pre-treatment of air-drying in fig halves, aiming at drying acceleration, energy savings and product quality improvement. The effect of solid/liquid mass ratio, process temperature (25-45 °C) and duration (up to 300 min) on water activity (a_w) and transport phenomena during OD, was modelled. The effective diffusion coefficients, drying time and energy consumption, were also calculated during air-drying at 50-70 °C. At optimum OD conditions (90 min, 45 °C), the highest water loss and solid gain ratio were achieved, while the a_w (equal to an initial value 0.986) was decreased to 0.929. Air-drying time of OD- and control samples was estimated at 12 and 21 h, at 60 °C, respectively, decreasing the required energy by up to 31.1%. Quality of dried figs was systematically monitored during storage. OD-assisted air-drying led to a product of improved quality and extended shelf-life.

Keywords: air-drying; energy consumption; figs; osmotic dehydration; quality; shelf-life.