THE INFLUENCE OF INDUSTRIAL DEHYDRATION ON QUALITY OF FIG FRUITS

Abstract

The effectiveness of a dehydration process on the quality of Niedda longa fig fruits was studied. Drying was carried out either with an industrial two-stage dehydration system, requiring no blanching treatment, or with a simulated sun-drying procedure. During the industrial process fruits were: (a) initially moved for 3 hours in a tunnel with a gradient air temperature from 95°C to 85°C; (b) then moved into a second tunnel at 85°C for 14 h. Sun-drying was simulated keeping fruits for 120 h at 32°C and 35% of relative humidity (RH). Finally dehydrated figs were rehydrated, or equilibrated with environmental RH (sun-dried figs), and both treated with potassium-sorbate solution, then film-packaged into hermetically sealed air tight bags. Moreover, half of the bags were packed in-modified atmosphere (MAP). Fruits were, then, stored at 20°C for 6 months. A 11 h dehydration time was sufficient to obtain microbially stable fruits without chemical treatments, reaching a dry matter content (DM) of 88 % and water activity (aw) of 0.60, whereas after 17 h DM and aw were 91% and 0.57, respectively. DM of industrial rehydrated figs and environmental equilibrated sun-dried figs were 71% and 74%, respectively, requiring a potassium-sorbate treatment. After packaging and 6 months of shelf life, no microbial growth was revealed on fruits. MAP resulted in no additional improvement on the microbial quality of the product. Based on these results we can state that industrial dehydration performed well, even if fruit calibration is needed before drying.