No abstract available

[en] Published in summary form only

[en] The great amount of waste produced by the food industry can be an interesting source of bioactive compounds. To this end, convective drying is one of the most extended method to stabilize the industrial by-products. However, drying conditions can affect not only drying kinetics but also the bioactivy of some compounds. Apple skin constitutes one of the main by-product generated in apple juice or cider production. It contains importantamounts of functional compounds such as polyphenols or vitamin C whoseextraction can be interesting. The main aim of this work was to determine the influence of drying conditions, temperature and application of ultrasound, in some quality parameters of dried apple skin. For this purpose, apple skin samples were dried at different temperatures (-10, 30, 50 and 70 oC) and with (20.5 kW/m3) or without application of ultrasound. Color, total phenolic content, antioxidant activity and vitamin C was measured in fresh and dried samples. The increase of drying temperature and the ultrasound slightly reduced the antioxidant properties of samples while no influence in sample color was observed. (Author)

[en] The MW heating at early or at final stage of drying process to obtain a crispy apple snack was studied. The effect of MW power and time of application was also evaluated on colour, texture, physico-chemical and sensory properties. Apple snack obtained with the MW heating (7.5 min at 3.000 W) at early stage after an osmotic pre-treatment resulted in apple slices more porous and with better sensory attributes than if it is applied at later stage of drying. (Author)

[en] Drying conditions for convective driers are often based on empirical approaches in which the final product quality is evaluated post processing. Modern sensor technology and data processing enable second-by-second quality analyses but conventional systems do not utilize this possibility. An industrial convective drying chamber was modified with a camera system to investigate the product during the drying process. The obtained data was analyzed on color alternation (CIE-L*a*b* color space and Browning Index), shrinkage and deformation. Both, shrinkage and deformation show minor dependence on drying conditons. The investigation shows the time depending optical parameter at different drying conditions. This might offer new 'smart' drying programs with focus on improved product quality. (Author)

[en] The great amount of waste produced by food industry contains interesting bioactive compounds. The extraction of these compounds requires the by-products previous stabilization being the convective drying one of most used techniques to this end. Drying conditions can affect both drying kinetics and final quality of products. The apple skin, by product of apple juice or cider industries, is rich in functional compounds such as polyphenols or vitamin C. The main goal of this contribution was to quantify the influence of temperature and ultrasound application in drying kinetics of apple skin. For this purpose, drying experiments at different temperatures (-10, 30, 50 and 70 ºC) and with (20.5 kW/m3) and without application of ultrasound were carried out. Drying kinetics were modelled by using a diffusion based model. As can be expected, the higher the temperature the faster the drying. Ultrasound application accelerated the process at every temperature tested being the influence slightly lower than found from the literature for other products. This can be attributed at the physical structure of the apple skin, less porous than the pulp. In any case, the application of ultrasound significantly reduced the drying time. (Author)

No abstract available

[en] In this paper, hot air drying (HAD) was applied when moisture content of apple slices range from 50% to 86%, and then vacuum-filling nitrogen drying (VFND) was used till moisture content reaching 7%. Results showed that, the drying rate of apple slice during VFND period increased with temperature increment and decreased with increment of slice thickness; compared to freezing dried samples, samples dried in this research were owned lower Vc and higher flavonoid; when HAD (70°C,3.0m/s)+VFND(relative pressure 0.08MPa, 50°C) and thickness of 6.0mm, nutrients reached better levels: retentions of Vc, total phenolics and flavonoid were 1.63mg/100g, 4.07mg/100g and 2.10mg/100g, respectively. (Author)

[en] This research work is about dehydrofreezing assisted by DIC treatment as an innovative conservation process of apple fruits. Samples previously dehydrated and DIC treated were frozen at -30 °C and at two different practical freezing rates. The effects of sample water content (W) and practical freezing rate (PFR) on freezing characteristics and apple texture were examined. Thaw exudate water (TEW) of 200% and 100% db samples was approximately 3 g/100 g water. Whereas, it was lower than 0.5 g/100 g water for samples with 30% db W during thawing at 4 °C. Moreover, the impact of PFR on TEW was significant and very important only for high W samples. For samples whose water content was lower than 100% db, firmness was as higher as the W was lower, without any significant impact of PFR. (Author)

No abstract available