Contribución al estudio de la aplicación de ultrasonidos de alta intensidad en procesos de secado a baja temperatura

Tesis por compendio[EN] Dehydration is one of the most commonly used operations in the food industry, and although its aim is to extend the shelf life of foods by reducing their water activity, it could also involve quality degradation. Vacuum freeze-drying may be considered one of the best drying methods for the purposes of preserving the organoleptic and nutritional properties of the fresh product, but its high processing cost limits its use to high value-added products. Convective drying at low temperatures could be considered an alternative means of obtaining high quality products at lower cost. However, the low drying rates at low temperatures (T<20ºC) and atmospheric pressure makes its industrial application difficult. In this sense, high intensity ultrasound (US) has been used to intensify mass transfer phenomena in food processing. It could be of great interest to apply US in low temperature drying because the ultrasonic effects are mainly mechanical (non-thermal). In this context, the main aim of this thesis was to determine the feasibility of US application in low temperature drying, addressing the effect on both the drying kinetics and the quality of the obtained products. For this purpose, apple, eggplant and cod samples were dried at different temperatures (-10, -5, 0, 5 and 10ºC), air velocities (1, 2, 4 and 6 m/s) and applying different ultrasonic powers (0, 25, 50 and 75 W). Diffusion models were used to describe the drying kinetics and to quantify the influence of the process variables. Moreover, different quality parameters (rehydration capacity, texture, antioxidant capacity...) of the dried products were determined. The application of US significantly (p<0.05) shortened the drying time under every drying condition and with each product tested, reducing the drying time by up to 80, 87 and 60% in apple, eggplant and cod samples, respectively. Thus, the greater the ultrasonic power applied, the shorter the drying time. The drying temperature and air velocity influenced the US efficiency and the best performance was achieved at the lowest drying temperatures and air velocities. In general terms, the diffusion model adequately fitted the drying kinetics of the three products tested. Although, in the case of US assisted drying, a better fit of the experimental data was obtained when the external resistance to water transfer was considered. The URIF (Uniformly Retreating Ice Front) model successfully fitted the atmospheric freeze drying kinetics. This model was validated under different experimental conditions. As regards the effect of the process variables on the quality parameters, in overall terms, it was observed that neither the US application nor the air velocity greatly influenced the quality of the obtained products. However, the temperature affected some quality parameters, such as rehydration capacity and color, especially at temperatures below the samples' freezing point. Finally, as a technology employed for the purposes of obtaining porous food matrices to be used further in the development of functional foods, US-assisted low temperature drying could be considered of great potential. Thus, from dried apple samples impregnated with olive leaf extract, it was observed that US application during drying did not significantly (p<0.05) influence the infusion capacity but did increase the antioxidant capacity of the final product. Therefore, high intensity ultrasound could be considered an interesting technology with which to speed-up the low temperature drying processes without greatly affecting the quality of the dried product.[ES] La deshidratación, una de las operaciones más utilizadas en la industria agroalimentaria, mejora la estabilidad de los alimentos al reducir su actividad de agua, aunque puede afectar a su calidad. Entre las diferentes técnicas de secado existentes, destaca la liofilización a vacío por ser una de las que mejor conservan las propiedades organolépticas y nutricionales de los productos. Sin embargo, esta operación resulta muy cara y sólo se utiliza en productos de alto valor añadido. El secado convectivo a baja temperatura (T<20ºC) representa una alternativa para obtener productos de alta calidad a menor coste aunque su baja velocidad de proceso dificulta su implementación a nivel industrial. En este sentido, los ultrasonidos de alta intensidad (US) se han aplicado para intensificar operaciones de transferencia de materia en diferentes procesos agroalimentarios. Sus efectos son principalmente mecánicos (no térmicos), por lo que su uso en el secado a baja temperatura resulta altamente interesante. En este contexto, el objetivo general de la presente tesis doctoral fue determinar la viabilidad de la aplicación de US en procesos de secado a baja temperatura, abordando tanto su efecto en la cinética como en la calidad de los productos obtenidos. Para ello, se deshidrataron muestras de manzana, berenjena y bacalao a diferentes temperaturas (-10, -5, 0, 5 y 10ºC) y velocidades de aire (1, 2, 4 y 6 m/s) y aplicando diferentes niveles de potencia acústica (0, 25, 50 y 75 W). Se utilizaron modelos difusivos para describir las cinéticas de secado y cuantificar la influencia de las variables de proceso. Además, se determinaron diferentes parámetros de calidad (capacidad de rehidratación, textura, capacidad antioxidante,¿) de los productos deshidratados. La aplicación de US permitió reducir significativamente (p<0.05) el tiempo de secado en todas las condiciones experimentales y productos analizados, obteniendo reducciones de tiempo de secado de hasta el 80, 87 y 60% en manzana, berenjena y bacalao, respectivamente. La reducción del tiempo de secado fue mayor cuanto mayor fue la potencia acústica aplicada. La temperatura y la velocidad del aire de secado influyeron en la efectividad de la aplicación de US, siendo mayor el efecto de los US a las temperaturas y velocidades más bajas. En general, la teoría difusional describió adecuadamente la cinética de secado de los tres productos estudiados. En las experiencias con aplicación de US se obtuvo un mejor ajuste a los datos experimentales cuando se consideró la resistencia externa en el modelo. Asimismo, en condiciones de liofilización a presión atmosférica, el modelo URIF (Uniformly Retreating Ice Front) se ajustó adecuadamente a los datos experimentales. Además, este modelo se validó en diferentes condiciones experimentales. Respecto al efecto de las variables de proceso en los parámetros de calidad, en general, se observó que ni la aplicación de US ni la velocidad de aire influyeron de manera importante en la calidad de los productos obtenidos. En cambio, la temperatura afectó de manera relevante a parámetros como la capacidad de rehidratación y el color, especialmente a temperaturas por debajo del punto de congelación de las muestras. Por otro lado, el secado a baja temperatura asistido con US tiene un alto potencial para la obtención de matrices porosas alimentarias para su posterior utilización en el desarrollo de alimentos funcionales. Así, en muestras de manzana deshidratada e impregnada con extracto de hoja de olivo, se observó que la aplicación de US durante el secado no afectó significativamente (p<0.05) a la capacidad de impregnación, pero sí incrementó la capacidad antioxidante del producto obtenido. Por lo tanto, los ultrasonidos de alta intensidad se pueden considerar como una tecnología interesante para acelerar los procesos de secado a baja temperatura sin afectar en gran medida a la calidad del producto obtenido.[CA] La deshidratació, una de les operacions més utilitzades en la indústria agroalimentària, millora l'estabilitat dels aliments en reduir la seua activitat d'aigua, encara que pot afectar-ne la qualitat. Entre les diferents tècniques d'assecatge que hi ha, destaca la liofilització al buit per ser una de les que millor conserven les propietats organolèptiques i nutricionals dels productes, però resulta molt cara i només s'utilitza en productes d'alt valor afegit. L'assecatge convectiu a baixa temperatura (T<20ºC) representa una alternativa per a obtenir productes d'alta qualitat a menor cost. No obstant això, la baixa velocitat d'assecatge dificulta la seua implementació a nivell industrial. En aquest sentit, els ultrasons d'alta intensitat (US) s'han aplicat per a intensificar operacions de transferència de matèria en diferents processos agroalimentaris. El seu ús en l'assecatge a baixa temperatura resulta altament interessant pel fet que els seus efectes són principalment mecànics (no tèrmics). En aquest context, l'objectiu general de la present tesi doctoral va ser determinar la viabilitat de l'aplicació d'US en processos d'assecatge a baixa temperatura, abordant tant l'efecte en la cinètica del procés com en la qualitat dels productes obtinguts. Amb aquesta finalitat, es van deshidratar mostres de poma, albergínia i bacallà a diferents temperatures (-10, -5, 0, 5 i 10ºC) i velocitats d'aire (1, 2, 4 i 6 m/s) i aplicant diferents nivells de potència acústica (0, 25, 50 i 75 W). Es van utilitzar models difusius per a descriure les cinètiques de l'assecatge i quantificar la influència de les variables del procés. A més, es van determinar diferents paràmetres de qualitat (capacitat de rehidratació, textura, capacitat antioxidant...) dels productes deshidratats. L'aplicació d'US va permetre reduir significativament (p<0.05) el temps d'assecatge en totes les condicions experimentals i tots els productes analitzats; es van obtenir reduccions de temps de fins al 80%, 87% i 60% en pomes, albergínies i bacallà, respectivament. La reducció del temps d'assecatge va ser més alta com més alta va ser la potència acústica aplicada. La temperatura i la velocitat de l'aire de l'assecatge van influir en l'efectivitat de l'aplicació d'US, sent major l'efecte dels US a les temperatures i velocitats més baixes. En general, la teoria difusional va descriure adequadament la cinètica de l'assecatge dels tres productes estudiats. En les experiències amb aplicació d'US es va obtenir un millor ajust a les dades experimentals quan es va considerar la resistència externa en el model. Així mateix, en condicions de liofilització a pressió atmosfèrica, el model URIF (Uniformly Retreating Ice Front) es va ajustar correctament a les dades experimentals. A més, aquest model es va validar en diferents condicions experimentals. Respecte a l'efecte de les variables del procés en els paràmetres de qualitat, en general, es va observar que ni l'aplicació d'US ni la velocitat de l'aire van influir de manera important en la qualitat dels productes obtinguts. En canvi, la temperatura va afectar de manera rellevant a paràmetres com la capacitat de rehidratació i el color, especialment a temperatures per davall del punt de congelació de les mostres. D'altra banda, l'assecatge a baixa temperatura assistit amb US presenta un alt potencial per a obtenir matrius poroses alimentàries per a la posterior utilització en el desenvolupament d'aliments funcionals. Així, en mostres de poma deshidratada i impregnada amb extracte de fulles d'olivera, es va observar que l'aplicació d'US durant l'assecatge no va afectar significativament (p<0.05) la capacitat d'impregnació, però sí que va incrementar la capacitat antioxidant del producte obtingut. Per tant, els ultrasons d'alta intensitat es poden considerar com una tecnologia interessant per a accelerar els processos d'assecatge a baixa temperatura sense afectar de manera reSantacatalina Bonet, JV. (2016). Contribución al estudio de la aplicación de ultrasonidos de alta intensidad en procesos de secado a baja temperatura [Tesis doctoral no publicada]. Universitat Politècnica de València. https://doi.org/10.4995/Thesis/10251/61484TESISCompendi

Estudio de la influencia del secado a baja temperatura en la capacidad de rehidratación y en la textura de berenjena y zanahoria

[ES] La deshidratación representa una operación muy importante en la industria alimentaria. El modo en el que se extrae el agua de los alimentos afecta a la calidad final del producto, por tanto las características de los productos deshidratados dependen del método de secado utilizado. El principal objetivo de este trabajo fue evaluar la influencia del secado a baja temperatura en la calidad de la berenjena y la zanahoria deshidratadas. Para alcanzar este objetivo, se obtuvieron muestras cúbicas (10 mm de lado) de berenjena (Solanum melongena var. Black Enorma) y zanahoria (Daucus carota var. Nantesa). Las muestras se deshidrataron utilizando tres técnicas diferentes: secado por aire caliente (SAC, 50 ºC y 2 m/s), liofilización a presión atmosférica (LPA, -14 ºC y 2 m/s) y liofilización a vacío (LV). Para evaluar la influencia del método de secado en la calidad final del producto deshidratado, se obtuvieron las cinéticas de rehidratación de las muestras SAC, LPA y LV. Asimismo, se realizó análisis del perfil de textura (TPA) para caracterizar la dureza de las muestras rehidratadas. Por otra parte, se utilizó un modelo difusivo para describir matemáticamente las cinéticas de secado y rehidratación de ambos productos. Las cinéticas de secado de berenjena fueron mucho más rápidas que las de zanahoria, tanto en SAC como en LPA. El método de secado influyó significativamente (p<0.05) tanto en el comportamiento en la rehidratación como en las propiedades texturales de berenjena y zanahoria. Las muestras LPA mostraron propiedades intermedias entre las muestras LV y SAC. Así, la LPA puede representar una alternativa interesante para obtener productos deshidratados de elevada calidad a menor coste que la LV.[EN] Dehydration represents a very important operation in food processing. The way how water is removed from food affects the final product quality, thus the characteristics of dried products are dependent on the drying technique used. The main objective of the present study was to evaluate the effect of low temperature drying on the quality of dried eggplant and carrot. For this purpose, cubic samples (10 mm side) were obtained from eggplants (Solanum melongena var. Black Enorma) and carrots (Daucus carota var. Nantesa). Samples were dehydrated using three different drying techniques: hot air drying (HAD, 50 ºC and 2 m/s), atmospheric freeze drying (AFD, -14 ºC and 2 m/s) and vacuum freeze drying (VFD). To evaluate the influence of drying method on the final quality of the product, rehydration kinetics of HAD, AFD and VFD samples were performed. Moreover, textural profile analyses (TPA) were carried out to characterize the hardness of the rehydrated samples. A diffusion model was used to mathematically describe drying and rehydration kinetics. The drying kinetics of eggplant were faster than carrot drying kinetics in both HAD and AFD. Drying method influenced significantly (p<0.05) in both rehydration behaviour and textural properties. AFD samples showed intermediate properties between VFD and HAD samples. Therefore, AFD could represent an interesting alternative to HAD and VFD to achieve high quality dried products at lower cost than VFD.[CA] La deshidratació representa una operació molt important en la indústria alimentària. La manera d'extraure l'aigua dels aliments afecta a la qualitat final del producte, per tant les característiques dels productes deshidratats depenen del mètode d'assecat utilitzat. El principal objectiu d'aquest treball fou avaluar la influència de l'assecat a baixa temperatura en la qualitat de l'albergínia i la carlota deshidratades. Per a aconseguir aquest objectiu, es van obtindre mostres cúbiques (10 mm de costat) d'albergínia (Solanum melongena var. Black Enorma) i carlota (Daucus carota var. Nantesa). Les mostres es van deshidratar utilitzant tres tècniques diferents: assecat per aire calent (SAC, 50 ºC i 2 m/s), liofilització a pressió atmosfèrica (LPA, -14 ºC i 2 m/s) i liofilització a buit (LV). Per a avaluar la influència del mètode d'assecat en la qualitat final del producte deshidratat, es van obtindre les cinètiques de rehidratació de les mostres SAC, LPA i LV. També es realitzaren anàlisis del perfil de textura (TPA) per a caracteritzar la duresa de les mostres rehidratades. D'altra banda, es va utilitzar un model difusiu per a descriure matemàticament les cinètiques d'assecat i rehidratació d'ambdós productes. Les cinètiques d'assecat d'albergínia van ser molt més ràpides que les de carlota, tant en SAC com en LPA. El mètode d'assecat va influir significativament (p<0.05) tant en el comportament en la rehidratació com en les propietats texturals d'albargina i carlota. Les mostres LPA van mostrar propietats intermèdies entre les mostres LV i SAC. Així, la LPA pot representar una alternativa interessant per a obtindre productes deshidratats d'elevada qualitat a menor cost que la LV.Santacatalina Bonet, JV. (2011). Estudio de la influencia del secado a baja temperatura en la capacidad de rehidratación y en la textura de berenjena y zanahoria. http://hdl.handle.net/10251/27917.Archivo delegad

Ultrasonically assisted low-temperature drying of desalted codfish

[EN] Low-temperature drying (LTD) constitutes an interesting means of dehydrating foodstuffs, thus preserving the quality of the product. Power ultrasound (US) generates several mechanical effects that could help to shorten the long drying times associated with LTD. In this work, the feasibility of using US in LTD of desalted cod was assessed. For this purpose, desalted cod slices (50 30 5 mm) were dried (2 m/s) at different temperatures (10, 0 and 10 C) without (AIR) and with (AIR þ US, 20.5 kW/m3) US application. Afterwards, the dried samples were rehydrated in distilled water (25 C). A diffusion model was used to describe both drying and rehydration kinetics. The color and hardness of both dried and rehydrated cod samples were also measured. The application of US increased the drying rate at every temperature tested, shortening the drying time by 16% at 0 C and up to 60% at 10 C. The ultrasonically assisted dried samples presented a rehydration rate which was slightly lower than that of those that had been conventionally dried, but they were harder and whiter, which is more suited to consumer preferences. Therefore, power ultrasound could be considered an affordable technology with which to accelerate LTD of desalted cod, providing high quality dried products.The authors acknowledge the financial support of the Spanish Ministerio de Economia y Competitividad (MINECO) - European Regional Development Fund (ERDF) from the project DPI2012-37466-CO3-03 and the FPI fellowship (BES-2010-033460) granted to J.V. Santacatalina. They also wish to acknowledge Carmen Cambra S.L. for their technical support with the selection of the raw material.Santacatalina Bonet, JV.; Guerrero, M.; García Pérez, JV.; Mulet Pons, A.; Cárcel Carrión, JA. (2016). Ultrasonically assisted low-temperature drying of desalted codfish. Food Science and Technology Research. 65:444-450. https://doi.org/10.1016/j.lwt.2015.08.023S4444506

Influence of drying on the retention of olive leaf polyphenols infused into dried apple

[EN] Olive leaf extracts are rich in polyphenolic compounds. Their inclusion by impregnation in food solid matrices could improve the nutritional value and antioxidant capacity of dietary products, such as apple. Drying the food matrix is interesting not only because it speeds up the infusion but also because of its effect on the final stabilization of impregnated food. In this work, the influence of drying method on the retention of infused olive leaf polyphenols in a solid matrix (apple) was addressed. For this purpose, apple cubes (10 mm side) were initially dehydrated by freeze drying or hot air drying at 60 °C and then impregnated with the olive leaf extract. After the polyphenolic infusion, samples were dried for the final stabilization by means of three different methods: freeze drying and hot air drying at 60 °C both with and without ultrasound application. The retention of infused polyphenols in apple samples was evaluated by determining the total phenolic content and antioxidant capacity and quantifying the main olive leaf polyphenols by HPLC-DAD/MS MS. The drying kinetics and the loss of apple solids during impregnation were modeled by using diffusion equations and the Weibull model, respectively. The role of fresh apple drying on the retention of infused olive leaf polyphenols was more significant than the further drying of the impregnated apple. Thus, hot air drying of fresh apple provided the highest antioxidant capacity (47.1±2.6 mg Trolox/g d.m.), and oleuropein contents in the final dried apple of up to 1,928 mg/100 g d.m. were foundThe authors thank the Generalitat Valenciana (PROMETEO/2010/062, PROMETEO/2012/007, and ACOMP/2013/93) for its financial support. M. H. Ahmad Qasem was the recipient of a fellowship from the Ministerio de Educacion, Cultura y Deporte of Spain (Programa de Formacion de Profesorado Universitario del Programa Nacional de Formacion de Recursos Humanos de Investigacion). This research has also been supported by the Ministerio de Ciencia e Innovacion (DPI2012-37466-C03-03, AGL2011-29857-C03-03) and CIBERobn (CB12/03/30038, Fisiopatologia de la Obesidad y la Nutricion, CIBERobn, Instituto de Salud Carlos III.Ahmad-Qasem Mateo, MH.; Santacatalina Bonet, JV.; Barrajón-Catalán, E.; Micol, V.; Cárcel Carrión, JA.; García Pérez, JV. (2015). Influence of drying on the retention of olive leaf polyphenols infused into dried apple. Food and Bioprocess Technology. 8(1):120-133. https://doi.org/10.1007/s11947-014-1387-6S12013381Ahmad-Qasem, M. H., Barrajón-Catalán, E., Micol, V., Mulet, A., & García-Pérez, J. V. (2013a). Influence of freezing and dehydration of olive leaves (var. Serrana) on extract composition and antioxidant potential. Food Research International, 50, 189–196.Ahmad-Qasem, M. H., Cánovas, J., Barrajón-Catalán, E., Micol, V., Cárcel, J. A., & García-Pérez, J. V. (2013b). Kinetic and compositional study of phenolic extraction from olive leaves (var. Serrana) by using power ultrasound. Innovative Food Science and Emerging Technologies, 17, 120–129.AOAC (1997). Official methods of analysis. Association of official analytical chemists. Virginia, USA.Barros, J. (2011). Innovations in food technology special issue. Food and Bioprocess Technology, 4, 831–832.Benzie, I. F. F., & Strain, J. J. (1996). The ferric reducing ability of plasma (FRAP) as a measure of “antioxidant power”: the FRAP assay. Analytical Biochemistry, 239, 70–76.Betoret, N., Puente, L., Díaz, M. J., Pagán, M. J., García, M. J., Gras, M. L., et al. (2003). Development of probiotic-enriched dried fruits by vacuum impregnation. Journal of Food Engineering, 56, 273–277.Blanda, G., Cerretani, L., Bendini, A., Cardinali, A., Scarpellini, A., & Lercker, G. (2008a). Effect of vacuum impregnation on the phenolic content of Granny Smith and Stark Delicious frozen apple cvv. European Food Research and Technology, 226, 1229–1237.Blanda, G., Cerretani, L., Cardinali, A., Bendini, A., & Lercker, G. (2008b). Effect of frozen storage on the phenolic content of vacuum impregnated Granny Smith and Stark Delicious apple cvv. European Food Research and Technology, 227, 961–964.Chemat, F., Huma, Z., & Khan, M. K. (2011). Applications of ultrasound in food technology: processing, preservation and extraction. Ultrasonics Sonochemistry, 18, 813–835.Cunha, L. M., Oliveira, F. A. R., & Oliveira, J. C. (1998). Optimal experimental design for estimating the kinetic parameters of processes described by the Weibull probability distribution function. Journal of Food Engineering, 37, 175–191.Cunningham, S. E., McMinn, W. A., Magee, T. R., & Richardson, P. S. (2008). Experimental study of rehydration kinetics of potato cylinders. Food and Bioproducts Processing, 86(1), 15–24.Esclápez, M. D., García-Pérez, J. V., Mulet, A., & Cárcel, J. A. (2011). Ultrasound-assisted extraction of natural products. Food Engineering Review, 3, 108–120.Fernandes, F. A. N., Rodrigues, S., Law, C. L., & Mujumdar, A. S. (2011). Drying of exotic tropical fruits: a comprehensive review. Food and Bioprocess Technology, 4(2), 163–185.Ferrando, M., Rózek, A., Achaerandio, I., & Güell, C. (2011). Grape phenolic infusion into solid foods: studies on mass transfer and antioxidant capacity. Procedia Food Science, 1, 1494–1501.Ferreira, D., Guyot, S., Marnet, N., Delgadillo, I., & Renard, C. M. G. C. (2002). Composition of phenolic compounds in a Portuguese pear (Pyrus communis L. var. S. Bartolomeu) and changes after sun-drying. Journal of Agricultural and Food Chemistry, 50, 4537–4544.García-Pérez, J. V., Cárcel, J. A., de la Fuente, S., & Riera, E. (2010). Ultrasonic drying of foodstuff in a fluidized bed: parametric study. Ultrasonics, 44(1), e539–e543.García-Pérez, J. V., Ortuño, C., Puig, A., Cárcel, J. A., & Pérez-Munuera, I. (2012). Enhancement of water transport and microstructural changes induced by high-intensity ultrasound application on orange peel drying. Food and Bioprocess Technology, 5(6), 2256–2265.Jack, F. R., O’Neill, J., Piacentini, M. G., & Schroder, M. J. A. (1997). Perception of fruit as a snack: a comparison with manufactured snack foods. Food Quality and Preference, 8, 175–182.Jankovié, M. (1993). Physical properties of convectively dried and freeze-dried berrylike fruits. Faculty of Agriculture, Belgrade, 38(2), 129–135.Joshi, A. P. K., Rupasinghe, H. P. V., & Khanizadeh, S. (2011). Impact of drying processes on bioactive phenolics, vitamin and antioxidant capacity of red-fleshed apple slices. Journal of Food Processing and Preservation, 35, 453–457.Karakaya, S. E. S. (2009). Studies of olive tree leaf extract indicate several potential health benefits. Nutrition Reviews, 67, 632–639.Khan, A. A., & Vincent, J. F. V. (1990). Anisotropy of apple parenchyma. Journal of the Science of Food and Agriculture, 52(4), 455–466.Lewicki, P. P., & Jakubczyk, E. (2004). Effect of hot air temperature on mechanical properties of dried apples. Journal of Food Engineering, 64, 307–314.Mahn, A., Zamorano, M., Barrientos, H., & Reyes, A. (2012). Optimization of a process to obtain selenium-enriched freeze-dried broccoli with high antioxidant properties. LWT--Food Science and Technology, 47, 267–273.Manzocco, L., Calligaris, S., Mastrocola, D., Nicoli, M., & Lerici, C. (2001). Review of non enzymatic browning and antioxidant capacity in processed foods. Trends in Food Science and Technology, 11, 340–346.Maskan, M. (2001). Drying shrinkage and rehydration characteristics of kiwifruits during microwave drying. Journal of Food Engineering, 48, 177–182.Menéndez, J. A., Joven, J., Aragonès, G., Barrajón-Catalán, E., Beltrán-Debón, R., Borrás-Linares, I., et al. (2013). Xenohormetic and anti-aging activity of secoiridoid polyphenols present in extra virgin olive oil: a new family of gerosuppressant agents. Cell Cycle, 12(4), 555–578.Mujumdar, A. S., & Law, C. L. (2010). Drying technology: trends and applications in postharvest processing. Food and Bioprocess Technology, 3(6), 843–852.Noorbakhsh, R., Yaghmaee, P., & Durance, T. (2013). Radiant energy under vacuum (REV) technology: a novel approach for producing probiotic enriched apple snacks. Journal of Functional Foods, 5, 1049–1056.Ortuño, C., Quiles, A., & Benedito, J. (2014). Inactivation kinetics and cell morphology of E. coli and S. cerevisiae treated with ultrasound-assisted supercritical CO2. Food Research International. doi: 10.1016/j.foodres.2014.05.012 .Ozuna, C., Gomez Alvarez-Arenas, T., Riera, E., Cárcel, J. A., & García-Pérez, J. V. (2014). Influence of material structure on air-borne ultrasonic application in drying. Ultrasonics. Sonochemistry. doi: 10.1016/j.ultsonch.2013.12.015 .Pulido, R., Bravo, L., & Saura-Calixto, F. (2000). Antioxidant activity of dietary polyphenols as determined by a modified ferric reducing/antioxidant power assay. Journal of Agricultural and Food Chemistry, 48(8), 3396–3402.Rózek, A., García-Pérez, J. V., López, F., Güell, C., & Ferrando, M. (2010). Infusion of grape phenolics into fruits and vegetables by osmotic treatment: phenolic stability during air drying. Journal of Food Engineering, 99, 142–150.Schieber, A., Stintzing, F. C., & Carle, R. (2001). By-products of plant food processing as a source of functional compounds-recent developments. Trends in Food Science & Technology, 12, 401–413.Schulze, B., Hubbermann, E. M., & Schwarz, K. (2014). Stability of quercetin derivatives in vacuum impregnated apple slices after drying (microwave vacuum drying, air drying, freeze drying) and storage. LWT--Food Science and Technology, 57, 426–433.Sham, P. W. Y., Scaman, C. H., & Durance, T. D. (2001). Texture of vacuum microwave dehydrated apple chips as affected by calcium pretreatment, vacuum level, and apple varieties. Journal of Food Science, 66(9), 1341–1347.Simal, S., Femenia, A., Garau, M. C., & Rosselló, C. (2005). Use of exponential, Page’s and diffusional models to simulate the drying kinetics of kiwi fruit. Journal of Food Engineering, 66, 323–328.Singleton, V. L., Ortholer, R., & Lamuela-Raventos, R. M. (1999). Analysis of total phenols and other oxidation substrates and antioxidants by means of Folin-Ciocalteu reagent. Methods in Enzymology, 299, 152–178.Spiess, W.E.L., & Behsnilian, D. (1998). Osmotic treatments in food processing. Current stage and future needs. In: A. Ziti (Eds.), Drying ’98, vol A, pp 47–56. Thessaloniki, Greece.Van Buggenhout, S., Lille, M., Messagie, I., Van Loey, A., Autio, K., & Hendrickx, M. (2006). Impact of pretreatment and freezing conditions on the microstructure of frozen carrots: quantification and relation to texture loss. European Food Research and Technology, 222(5–6), 302–308.Vega-Gálvez, A., Ah-Hen, K., Chacana, M., Vergara, J., Martínez-Monzó, J., García-Segovia, P., et al. (2012). Effect of temperature and air velocity on drying kinetics, antioxidant capacity, total phenolic content, color, texture and microstructure of apple (var. Granny Smith) slices. Food Chemistry, 132, 51–59.Voda, A., Homan, N., Witek, M., Duijster, A., Van Dalen, G., Van der Sman, R., et al. (2012). The impact of freeze-drying on microstructure and rehydration properties of carrot. Food Research International, 49, 687–693.Zandstra, E. H., Graaf, C. D., & Staveren, W. A. V. (2001). Influence of health and taste attitudes on consumption of low and high-fat foods. Food Quality and Preference, 12, 75–82

Influencia de la aplicación de ultrasonidos de potencia en las cinéticas de secado, el contenido polifenólico y la capacidad antioxidante de manzana (cv. Granny Smith)

[EN] The main objective of this study was to evaluate the effect of power ultrasound application on hot air drying kinetics of apple and polyphenol content and the antioxidant capacity of the dried product. For this purpose, apple (Malus domestica cv. Granny Smith) cubes (10 mm side) were dried in a convective drier, at constant air velocity (1 m/s), different temperatures (30, 50 and 70ºC), without (0 W) and with the application of power ultrasound (45 W and 75 W). Both high temperatures and power ultrasound application led to a significant (p<0.05) reduction of drying time and increased the effective moisture diffusivity. In overall terms, the antioxidant capacity and polyphenol content of apple samples was better preserved when the drying time was shortened. Therefore, ultrasonic application could be considered an adequate technology with which to intensify convective drying of apple preserving antioxidant capacity.[ES] El principal objetivo de este estudio fue evaluar el efecto de la aplicación de ultrasonidos de potencia en las cinéticas de secado por aire caliente de manzana y en el contenido polifenólico y la capacidad antioxidante del producto seco. Para alcanzar este objetivo, se deshidrataron cubos (10 mm de arista) de manzana (Malus domestica cv. Granny Smith) en un secadero convectivo, a velocidad de aire constante (1 m/s), diferentes temperaturas (30, 50 y 70ºC), sin (0 W) y con la aplicación de ultrasonidos de potencia (45 W y 75 W). Tanto las altas temperaturas como la aplicación de ultrasonidos de potencia produjeron una significativa (p<0.05) reducción del tiempo de secado y aumentaron la difusividad efectiva. De manera general, se observó que la capacidad antioxidante y el contenido polifenólico de las muestras de manzana se conservaron mejor cuando se disminuyó el tiempo de secado. Por tanto, la aplicación de ultrasonidos se puede considerar una tecnología adecuada con la que se intensifica el secado convectivo de manzana y se conserva la capacidad antioxidante.Los autores agradecen al Ministerio de Economía y Competitividad (MINECO) su financiación para la realización de este trabajo a través de los proyectos DPI2009-14549-C04-01, DPI2009-14549-C04-02 y DPI2009-14549-C04-04, de igual manera a la Consellería de Innovación, Interior y Justicia de la CAIB por la beca predoctoral FPI y el Proyecto 57/2011.Santacatalina Bonet, JV.; Rodríguez, O.; Riera, E.; Simal, S.; García Pérez, JV. (2012). Influencia de la aplicación de ultrasonidos de potencia en las cinéticas de secado, el contenido polifenólico y la capacidad antioxidante de manzana (cv. Granny Smith). Revista de Acústica. 1-12. http://hdl.handle.net/10251/78949S11

Impact of applied ultrasonic power on the low temperature drying of apple

[EN] Low temperature drying (LTD) allows high-quality dried products to be obtained, preserving the nutritional properties of fresh foods better than conventional drying, but it is a time-consuming operation. Power ultrasound (US) could be used to intensify LTD, but it should be taken into account that process variables, such as the level of applied power, have an influence on the magnitude and extension of the ultrasonic effects. Therefore, the aim of this work was to assess the influence of the level of applied ultrasonic power on the LTD of apple, analyzing the drying kinetics and the quality of the dried product. For that purpose, apple (Malus domestica cv. Granny Smith) cubes (8.8 mm side) were dried (2 m/s) at two different temperatures (10 and -10 degrees C), without and with (25, 50 and 75W) US application. In the dried apple, the rehydration kinetics, hardness, total phenolic content, antioxidant capacity and microstructure were analyzed to evaluate the impact of the level of applied ultrasonic power. At both temperatures, 10 and -10 degrees C, the higher the ultrasonic power level, the shorter the drying time; the maximum shortening of the drying time achieved was 80.3% (at -10 degrees C and 75W). The ultrasonic power level did not significantly (p < 0.05) affect the quality parameters analyzed. Therefore, US could be considered a non-thermal method of intensifying the LTD of fruits, like apple, with only a mild impact on the quality of the dried product. (C) 2015 Elsevier B.V. All rights reserved.The authors acknowledge the financial support of the Spanish Ministerio de Economia y Competitividad (MINECO) and the European Regional Development Fund (ERDF) for the project DPI2012-37466-CO3-03 and the FPI fellowship (BES-2010-033460) Granted to J.V. Santacatalina.Contreras-Ruiz, M.; Santacatalina Bonet, JV.; Cárcel Carrión, JA.; Simal, S.; García Pérez, JV. (2016). Impact of applied ultrasonic power on the low temperature drying of apple. Ultrasonics Sonochemistry. 28:100-109. https://doi.org/10.1016/j.ultsonch.2015.06.027S1001092

Influence of power ultrasound application on drying kinetics of apple and its antioxidant and microstructural properties

[EN] The effect of drying air temperature and power ultrasound (US) application on the drying curves of apples (var. Granny Smith) and on the quality (total polyphenol (TPC) and flavonoid (FC) contents, the antioxidant activity (AA) and microstructure after drying) have been evaluated. Drying curves were studied at air temperatures of 30 degrees C, 50 degrees C, and 70 degrees C; without ultrasound (AIR) and using two levels of ultrasonic power: 18.5 kW/m(3) (AIR + US1) and 30.8 kW/m(3) (AIR + US2), being the drying time significantly (p < 0.05) reduced as these two operational variables increased. A diffusional model, taking into account the influence of drying temperature and US power on both the diffusion and the external mass transfer coefficients allowed the accurate simulation of the drying curves (MRE = 5.8 +/- 2.1%). TPC and FC were affected by drying temperature and US application. In AIR samples, the increase of drying temperature led to lower losses of TPC, FC, and AA. The US application (AIR + US1 and AIR + US2) involved lower TPC and FC losses in comparison to AIR samples only at 30 degrees C. The use of US promoted notorious changes in the microstructure (SEM observation) of apple samples, in comparison to the samples dried without US at all the temperatures considered, due to the stress developed by ultrasonic waves. (C) 2014 Elsevier Ltd. All rights reserved.The authors want to acknowledge the Spanish Government (MICINN), and European Regional Development Fund (FEDER), the European Social Fund (FSE), the Generalitat Valenciana and the Govern de les Illes Balears for the financial support (DPI2009-14549-C04-02, DPI2012-37466-C03-02, DPI2012-37466-C03-03, AGL 2012-34627, PROMETEO/2010/062, Project 57/2011).Rodríguez, O.; Santacatalina Bonet, JV.; Simal Florindo, S.; García Pérez, JV.; Femenia, A.; Rossello Matas, C. (2014). Influence of power ultrasound application on drying kinetics of apple and its antioxidant and microstructural properties. Journal of Food Engineering. 129:21-29. https://doi.org/10.1016/j.jfoodeng.2014.01.001S212912

Ultrasonic characterization of pork fat crystallization during cold storage

[EN] In this work, the feasibility of using ultrasonic velocity measurements for characterizing and differentiating the crystallization pattern in 2 pork backfats (Montanera and Cebo Iberian fats) during cold storage (0 degrees C, 2 degrees C, 5 degrees C, 7 degrees C, and 10 degrees C) was evaluated. The fatty acid profile, thermal behavior, and textural properties (hardness) of fat were also determined. Both fats became harder during cold storage (average hardness increase for both fats, 11.5 N, 8 N, and 1.8 N at 0, degrees C 2 degrees C, and 5 degrees C , respectively), showing a 2-step pattern related with the separate crystallization of the different existing triacylglycerols, which was well described using a modified Avrami equation (explained variance > 99%). Due to a greater content of saturated triacylglycerols, Cebo fat (45.1%) was harder than Montanera (41.8%). The ultrasonic velocity followed a similar 2-step pattern to hardness during cold storage, being found an average increase for both fats of 184, 161, and 150 m/s at 0 degrees C 2 degrees C, and 5 degrees C, respectively. Thus, ultrasonic measurements were useful both to characterize the textural changes taking place during cold storage and to differentiate between fats with different composition. Practical ApplicationThe cold storage of dry-cured meat products during their distribution and retail sale exert an important effect on their textural properties and consumers' acceptance due to the crystallization of the fat fraction, which is greatly influenced by the type of fat. In this work, a nondestructive ultrasonic technique was used to identify the textural changes provoked by the crystallization during cold storage, and to differentiate between fats, which could be used for quality control purposes.The authors acknowledge the financial support from the "Ministerio de Economia y Competitividad" in Spain (Project RTA 2010-00029-C04-02).Corona Jiménez, E.; García Pérez, JV.; Santacatalina Bonet, JV.; Ventanas, S.; Benedito Fort, JJ. (2014). Ultrasonic characterization of pork fat crystallization during cold storage. Journal of Food Science. 79(5):828-838. https://doi.org/10.1111/1750-3841.12410S82883879