Guava is widely consumed because of its agro-industrial use, and its antioxidant properties attributed to vitamin C and carotenoids content. However, it has a short shelf life. Guava has been dried by atomization, fluidized bed, lyophilization (FD) and convective drying (CD). CD requires long operation times and the product characteristics are not desirable. In contrast, FD produces high quality products, but requires long processing times, high energy consumption and high operation costs. As an alternative, the Refractance Window^® (RW) drying is relatively simple and cheap technique. The objective of this study was to compare the effect of CD, FD and RW techniques, on the moisture content, water activity, color, porosity, volume change, vitamin C and carotenoids content in guava samples. The samples dried by RW required less time to reduce the moisture content and exhibited smaller changes in color than CD or FD. There were greater losses of carotenoids and vitamin C when drying by CD whereas RW had similar losses than FD. Lyophilized products exhibited minor change in volume and greater porosity. RW results in better retention of properties, compared with other drying techniques. Based on this, RW is a promising technique for the development of guava snacks.

The food industry has increased its interest in using “consumer-friendly” and natural ingredients to produce food products. In the case of emulsifiers, one of the possibilities is to use biopolymers with emulsification capacity, such as octenyl succinic anhydride modified starch, which can be used in combination with other polysaccharides, such as chitosan and carboxymethylcellulose, in order to improve the capacity to protect bioactive compounds. In this work, multilayer nano-emulsion systems loaded with oregano essential oil were produced by high energy methods and characterized. The process optimization was carried out based on the evaluation of particle size, polydispersity index, and zeta potential. Optimal conditions were achieved for one-layer nano-emulsions resulting in particle size and zeta potential of 180 nm and −42 mV, two layers (after chitosan addition) at 226 nm and 35 mV, and three layers (after carboxymethylcellulose addition) of 265 nm and −1 mV, respectively. The encapsulation efficiency of oregano essential oil within nano-emulsions was 97.1%. Stability was evaluated up to 21 days at 4 and 20 °C. The three layers nano-emulsion demonstrated to be an efficient delivery system of oregano essential oil, making 40% of the initial oregano essential oil available versus 13% obtained for oregano essential oil in oil, after exposure to simulated digestive conditions.

In most cases, conventional drying produces inferior quality products and requires higher drying times. A continuous pilot Refractance Window^® equipment was used to dry Aloe vera gel slabs of 5 and 10 mm thick at 60, 70, 80, and 90 °C, seeking a dry product with high-quality retention. Based on five empirical models, drying kinetics, diffusion coefficient, and activation energy were analyzed. Midilli–Kuck was the best predicting model. Short drying times (55–270 min) were needed to reach 0.10 g water/g solid. In addition, the technique yielded samples with high rehydration capacity (24–29 g water/g solid); high retention of color (∆E, 3.74–4.39); relatively low losses of vitamin C (37–59%) and vitamin E (28–37%). Regardless of the condition of temperature and sample thickness, a high-quality dried Aloe vera gel could be obtained. Compared with other methods, Refractance Window^® drying of Aloe vera achieved shorter drying times with higher quality retention in terms of color, vitamins C and E, and rehydration. Finally, the dried Aloe vera gel could be reconstituted to a gel close to its fresh state by rehydration.

Colombian mango production, which exceeded 261,000 t in 2020, generates about 40% of the whole fruit as solid waste, of which more than 50% are seed kernels (over 52,000 t solid by-product); though none is currently used for commercial purposes. This study reports the results of the supercritical carbon dioxide (scCO₂) extraction of an oil rich in essential fatty acids (EFAs) from revalorized mango seed kernels and the optimization of the process by the Response Surface Methodology (RSM). In pilot-scale scCO₂ experiments, pressure (23–37 MPa) and temperature (52–73 °C) were varied, using 4.5 kg of CO₂. The highest experimental oil extraction yield was 83 g/kg (37 MPa and 63 °C); while RSM predicted that 84 g/kg would be extracted at 35 MPa and 65 °C. Moreover, by fine-tuning pressure and temperature it was possible to obtain an EFA-rich lipid fraction in linoleic (37 g/kg) and α-linolenic (4 g/kg) acids, along with a high oleic acid content (155 g/kg), by using a relatively low extraction pressure (23 MPa), which makes the process a promising approach for the extraction of oil from mango waste on an industrial scale, based on a circular economy model.

Se evaluó el efecto del tamaño de partícula (250 pm y 180 pm) sobre la humectabilidad, solubilidad, capacidad de retención de agua (CRA), capacidad de retención de aceite (CRAC) e hinchazón en polvos liofilizados obtenidos de cáscaras de mango de las variedades criollo, Keitt, y Tommy Atkins. Además, se evaluó el contenido de antocianinas, carotenoides, licopeno y ácido ascórbico. El tamaño y la variedad influyeron significativamente (p<0.05) sobre las propiedades funcionales de los polvos; a mayor diámetro, menor fue el tiempo de humectabilidad y mayor CRA y CRAC; y a menor diámetro mayor fue la solubilidad. El polvo de la variedad criollo mostró la mayor humectabilidad, solubilidad, contenido de antocianinas y ácido ascórbico. Las variedades Tommy Atkins y Keitt presentaron valores más altos de CRA (7.79-8.18 g.g-1) y CRAC (4.15-4.71 g.g-1). El estudio muestra que los polvos de cáscara de mango pueden utilizarse para el desarrollo de alimentos funcionales.

Resumen Resumo Mass transfer in osmotic dehydration at atmospheric pressure has been basically modeled using a Fick's law solution (Crank model), which is the best known phenomenological model. Some authors have developed empirical models using mass balances and variable correlations. Frequently, some other authors obtain correlations using multiple regression analysis with second order polynomials. Hydrodynamic mechanism model (HDM) is used for processes that involve vacuum pressures. The purpose of this work is to discuss some of the models used to simulate osmotic dehydration processes. © 2005 Altaga. All rights reserved. La transferencia de masa en el proceso de deshidratación osmótica a presión atmosférica se modela fenomenológicamente utilizando generalmente el modelo de Crank que consiste en una solución de la ley de Fick. Las demás alternativas que existen para modelar el proceso de deshidratación osmótica, corresponden a modelos empíricos. Algunos de éstos modelos se desarrollaron a partir de ajustes polinómicos y otros, a partir de los balances de masa y de las relaciones entre las variables del proceso. Para procesos que involucran presiones de vacío, la transferencia de masa se representa principalmente con el modelo del Mecanismo Hidrodinámico (HDM). El objetivo de este trabajo es presentar los modelos matemáticos más utilizados en la literatura para simular el proceso de deshidratación osmótica, haciendo un análisis crítico de los mismos. © 2005 Altaga. Todos los derechos reservados. Palabras clave: Deshidratación osmótica, modelos matemáticos, transferencia de masa A transferencia de masa no proceso de deshidratación osmótica a presión atmosférica modélase fenomenolóxicamente empreñando xeralmente o modelo de Crank que consiste nunha solución da lei de Fick. As demáis alternativas que existen para modela-lo proceso de deshidratación osmótica, corresponden a modelos empíricos. Algúns destes modelos desenroláron-se a partir de axustes polinómicos e outros, a partir dos balances de masa e das relacións entre as variables do proceso. Para procesos que involucran presións de vacío, a transferencia de masa represéntase principalmente co modelo do Mecanismo Hidrodinámico (HDM). O obxetivo deste traballo é presenta-los modelos matemáticos máis empregados na literatura para simula-lo proceso de deshidratación osmótica, facendo unha analise crítica dos mesmos. © 2005 Altaga. Tódolos dereitos reservados. Palabras clave: Deshidratación osmótica, modelos matemáticos, transferencia de masa