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

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 (aw) 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 aw (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.

Can unexploited biomass of Ficus carica L. be valorized as a bio‐based material for the development of functional food formulations?

“…Techniques that affect cell structure and improve water loss can greatly enhance energy saving and reduce drying times. Osmotic dehydration 17 and ultrasonication 18 for example, are often used prior to drying since they effectively allow moisture loss via differentiation in solute concentration, or increased cell membrane porosity respectively. While retention of color, texture and nutritional value was observed in figs pre‐treated with these techniques, we would argue, that some loss of water‐soluble bioactive compounds is inevitable 19 .…”

Incorporation of Acid Whey Yogurt By-Product in Novel Sauces Formulation: Quality and Shelf-Life Evaluation

“…The total carbohydrates content was determined for all studied sauces using a modified protocol of the Debois assay [29] and was expressed as g lactose/100 g d.w. Individual sugars (fructose, glucose, lactose and glycerol) and organic acids (citric, mallic, tartaric and lactic) were determined by using the high performance liquid chromatography (HPLC) method as described by Andreou, Giannoglou, Thanou, Giannakourou and Katsaros [30]. Analysis of sugars and organic acids was carried out using a Repromer H column (300 mm, 7.8 mm; particle size: 9 µm) with a flow of 0.5 mL/min at 50 • C. Twenty (20) µL of the extracts were injected into the HPLC system.…”

Assessment of Parameters to Apply Osmotic Dehydration as Pretreatment for Improving the Efficiency of Convective Drying of Cassava Bagasse

“…Based on this, an immersion time of 10 min was defined and used to carry out all subsequent tests, corresponding to the application of OD as pretreatment of convective drying. In the state of the art immersion times of 1, 1.5, 2, 4, 5, 12, 16, 24, and up to 48 h were found [1,31,39,[41][42][43][44][45]. To reach equilibrium, long periods of time are generally needed.…”