Developing active chitosan-based edible film for extending the shelf life of guacamole

This study aimed to evaluate the effect of edible films (EFs) on important parameters of fresh guacamole and to select the best EF for evaluating its stability and protection effect after 28 days of storage (at 4 and 20°C). EFs based on chitosan (2%), glycerol (1%), citric acid (1.5–2.5%), and lemon-onion extract (0–2%) were applied on the surface of fresh guacamole to evaluate its effect in its color and microbiological and antioxidant properties after 48 h of storage (at 4 and 20°C). Results indicated that EFs delay the total color change and increase the antioxidant capacity of guacamole, while the microbial count was less than 100 CFU/g and 10 CFU/g for mesophylls and molds plus yeasts, respectively. According to the lowest total color change (7.93–14.92) and highest antioxidant capacity (1201.22 mg Trolox/100 g), EF1 (2% chitosan, 1% glycerol, 1.5% citric acid, and 2% lemon-onion extract) was selected for its analysis during the storage. After 28 d of storage at 4 and 20°C, a slight change in the physical characteristics of the EF was observed, while microbial load and antioxidant properties remained constant. Moreover, the selected EF maintained its capacity to avoid guacamole browning, being well-accepted by consumers (I like - I like much) who did not detect the application of EF, even after 24 h of its application onto the fresh guacamole. Results presented in this study indicated that developed EF maintained the quality characteristics of guacamole, and its effect did not change after 28 d of storage

Control L2/D

The paper present the formal conception of  parametric geometric control, the translation to natural language, current applications and its prospective analysis are described. The main purpose of the paper is to spread the knowledge of the  control fundamentals among the Spanish-speaking Latin American academic community, to comment its parsimony principle (the capacity of the production optimal control signals with minimum control actions) and to give an overview of future applications such as the control of mechanical ventilators and other biomedical engineered devices.Se presenta la concepción formal del control geométrico paramétrico en , su interpretación en lenguaje natural, sus aplicaciones actuales y su análisis prospectivo. El objetivo del artículo es hacer extensivo el conocimiento del control  a la comunidad Académica de México y de Habla Hispana, comentar su principio de parsimonia (generar respuestas de control óptimo con un mínimo de acción de control) y plantear perspectivas de futuras aplicaciones como por ejemplo en la ingeniería biomédica

The impact of convective drying on the color, phenolic content and antioxidant capacity of noni (Morinda citrifolia L.)

Abstract The effect of thin-layer drying temperature on color, phenolic content and antioxidant capacity of noni slices was investigated. Noni slices were air-dried at 50, 60 and 70 °C under natural convection conditions. Drying curves were fitted to thin-layer drying models in order to evaluate the drying characteristics of the product. In addition, an unsteady-state diffusion equation was numerically solved considering both product shrinkage and a variable mass Biot number in boundary condition to accurately estimate water diffusivity in a process with external resistance to mass transfer. Results revealed that the Aghbashlo model accurately reproduced the experimental behavior. As expected, water diffusivities, corrected for shrinkage, increased with the use of higher drying temperatures, with values in the range of 1.80-3.19 to ×10-9 m2/s. On the other hand, while drying caused a reduction in product lightness (24-31%) and total phenolic content (20-28%), the antioxidant capacity of dried noni was high (82-93% DPPH inhibition), which is advantageous for the further storage or processing of this fruit

Production, chemical, physical and technological properties of antioxidant dietary fiber from pineapple pomace and effect as ingredient in sausages

In this study, fresh and steamed under pressure (SPP) pineapple pomace were used to produce dietary fiber concentrates (DFCs) dried by freeze-drying or hot air-drying. Chemical, physical and technological properties were determined to select one pineapple DFC (PDFC) and to evaluate its mixture effect with meats on characteristics of Vienna-type sausages. The PDFC produced from SPP and hot air-dried (SPDFC-HD) had the highest content of DF, carotenoids, polyphenols such as gallic, cinnamic and p-coumaric acids, antioxidant capacity and hydration properties. Microstructural analysis evidenced a cell wall disruption of the PDFCs matrix by the effect of processing. The cubic model equations showed that with the increase in SPDFC-HD in the ternary mixture, a reducing effect on nitrites, moisture, shear force and shrinkage was obtained in sausages, while carotenoids and antioxidant polyphenols increased. This study demonstrated that SPDFC-HD was produced with characteristics to be used as ingredient in potential functional sausages