Application of power ultrasound on the convective drying of fruits and vegetables: effects on quality

This is the peer reviewed version of the following article:Rogríguez, Óscar, Eim, Valeria S., Roselló Matas, Carmen, Femenía, Antonio, Carcel Carrión, Juan Andrés, Simal, Susana. (2018). Application of power ultrasound on the convective drying of fruits and vegetables: effects on quality.Journal of the Science of Food and Agriculture, 98, 5, 1660-1673. DOI: 10.1002/jsfa.8673, which has been published in final form at http://doi.org/10.1002/jsfa.8673. This article may be used for non-commercial purposes in accordance with Wiley Terms and Conditions for Self-Archiving.[EN] Drying gives rise to products with a long shelf life by reducing the water activity to a level that is sufficiently low to inhibit the growth of microorganisms, enzymatic reactions and other deteriorative reactions. Despite the benefits of this operation, the quality of heat sensitive products is diminished when high temperatures are used. The use of low drying temperatures reduces the heat damage but, because of a longer drying time, oxidation reactions occur and a reduction of the quality is also observed. Thus, drying is a method that lends itself to being intensified. For this reason, alternative techniques are being studied. Power ultrasound is considered as an emerging and promising technology in the food industry. The potential of this technology relies on its ability to accelerate the mass transfer processes in solid-liquid and solid-gas systems. Intensification of the drying process with power ultrasound can be achieved by modifying the product behavior during drying, using pre-treatments such as soaking in a liquid medium assisted acoustically or, during the drying process itself, by applying power ultrasound in the gaseous medium. This review summarises the effects of the application of the power ultrasound on the quality of different dried products, such as fruits and vegetables, when the acoustic energy is intended to intensify the drying process, either when the application is performed before pretreatment or during the drying process. (c) 2017 Society of Chemical IndustryWe thank Conselleria d'Agricultura, Medi Ambient i Territori and Fons de Garantia Agraria i Pesquera de les Illes Balears (FOGAIBA) and the Spanish Government (MEIC) for financial support (RTA2015-00060-C04, AIA01/15).Rogríguez, Ó.; Eim, VS.; Roselló Matas, C.; Femenía, A.; Carcel Carrión, JA.; Simal, S. (2018). Application of power ultrasound on the convective drying of fruits and vegetables: effects on quality. Journal of the Science of Food and Agriculture. 98(5):1660-1673. https://doi.org/10.1002/jsfa.8673S16601673985Fernandes, F. A. N., Rodrigues, S., Cárcel, J. A., & García-Pérez, J. V. (2015). 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Acoustically assisted supercritical CO2 extraction of cocoa butter: Effects on kinetics and quality

[EN] The effect of high power ultrasound (US) application and pressure on the supercritical fluid extraction (SFE) kinetics of cocoa butter and on characteristics of the extracted cocoa butter (fatty acids composition, transition temperatures, polyphenol content and antioxidant activity) has been evaluated. Extraction experiments were carried out at 40 degrees C and at two pressure levels of 400 bar and 550 bar, without and with US application of 50 +/- 5 W, the extraction yield being significantly improved as the pressure increased and the ultrasound was applied. A Weibull model allowed the accurate simulation of the extraction curves, considering a constant shape factor alpha which was affected only by the US application, whilst the rate constant beta was affected by both pressure and US application. In general, for all cocoa butter samples, the transition temperatures observed corresponded to the polymorph alpha, T-c = 9.9 +/- 0.3 degrees C and T-m = 20.2 +/- 0.4 degrees C. With regard to the fatty acid composition, the stearic (37.8 +/- 0.8%), oleic (33.7 +/- 0.2%), and palmitic (26.0 +/- 0.6%) were the major acids, and none were found to be influenced by either pressure or ultrasound application. Similarly, the total polyphenol content and antioxidant activity were not affected by extraction conditions. The microstructure of cocoa beans after processing was affected by pressure and also by ultrasound application which promoted a breaking of the cell arrangement, facilitating the butter extraction. (C) 2014 Elsevier B.V. All rights reserved.The authors would like to acknowledge the Spanish Government (MICINN), and European Regional Development Fund (FEDER), the European Social Fund (FSE) and the Govern de les Illes Balears for their financial support (DPI2009-14549-C04-02, DPI2012-37466-C03-02, AGL 2012-34627, Project 57/2011).Rodríguez, Ó.; Ortuño Cases, C.; Simal Florindo, S.; Benedito Fort, JJ.; Femenia, A.; Roselló Matas, C. (2014). Acoustically assisted supercritical CO2 extraction of cocoa butter: Effects on kinetics and quality. Journal of Supercritical Fluids. 94:30-37. https://doi.org/10.1016/j.supflu.2014.06.017S30379