Browsing by Author "Quevedo, R."
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- ItemColor changes in the surface of fresh cut meat: A fractal kinetic application(2013) Quevedo, R.; Valencia, E.; Cuevas, G.; Ronceros, B.; Pedreschi, F.; Bastias, J. M.Color stability of fresh meat gives an idea about possible consumer preferences based on the appearance of the product, and it is an important property that influences its market value and the consumer's purchase decision. Color changes on the surface of fresh cut meat were evaluated applying fractal kinetic analysis based on the redness color value (a* value from CIELab and R value from RGB) as an alternative to the traditional method where an average of the color intensity is used; in addition the thiobarbituric acid and metmyoglobin content in the meat samples were measured. The kinetic rate and the shape factor (empirical order) values were calculated from data fitted to the power law model. In the experiments, freshly cut samples of meat were placed on a styrofoam tray and the fresh cut surface was evaluated for color and color stability using a computer vision system. The styrofoam tray with the samples was placed inside an environmental test chamber at 5 degrees C (+/- 1 degrees C) and at 85% relative humidity for 2.2 days. The results showed that it is possible to model changes in the intensity of the redness color in meat using fractal kinetic analysis, and that fractal dimension can be used as an indicator of changes in the non-homogenous distribution of the colors associated with redness intensity. (C) 2013 Elsevier Ltd. All rights reserved.
- ItemComputer Vision and Stereoscopy for Estimating Firmness in the Salmon (Salmon salar) Fillets(2010) Quevedo, R.; Aguilera, J. M.The computer vision and a stereoscopy technique were used to characterize and detect changes in the capacity of the salmon fillet surface to recover its original form after a constant weight was applied. A curvature index (associated to fillet firmness) calculated by means of 3D information data obtained with the stereoscopy technique from the fat stripe on the fillets was estimated over 6 months and was suggested as a characteristic of the recovery property of the fresh salmon fillet surface. Simultaneously, instrumental firmness using a LFRA1500 texture was measured. The values for the fresh salmon fillet measurement curvature index during a period of 6 months were established in the range of 0.05 and 0.10 (dimensionless), and this value was used in the experiments to represent fresh salmon fillets. Changes in the curvature index (associated with similar changes in firmness) for salmon fillet surface treated with enzymes (pepsin and papain) were registered on the second day during storage at 2 A degrees C. In general, stereoscopy is a technique that can be used on salmon fillets to detect changes in the recovery properties of the salmon fillet surface and to determine when salmon fillets can be classified as a fillet that has not been processed with enzymes.
- ItemCorrelation of the fractal enzymatic browning rate with the temperature in mushroom, pear and apple slices(2016) Quevedo, R.; Pedreschi Plasencia, Franco; Bastias, J. M.; Díaz, O.
- ItemDetermination of senescent spotting in banana (Musa cavendish) using fractal texture Fourier image(ELSEVIER SCI LTD, 2008) Quevedo, R.; Mendoza, F.; Aguilera, J. M.; Chanona, J.; Gutierrez Lopez, G.The analysis of fractal texture reflects a change in pixel intensity, and this might contain information about the structure of objects since a great change in intensity might usually indicate changes in the object. In the images of banana surfaces, the texture image can, to some extent, reflect changes and thus it can be used as an indicator of the last stage during the ripening process (over-ripening). In this experiment, bananas (Musa cavendish) were stored during 10 days at 20 degrees C. Images of banana surfaces were recorded using a computational vision system. The over-ripening process of bananas was represented by an increment in the fractal value derived from texture fractal Fourier analysis. The result shows that fractal texture derived from the spectral Fourier analysis increased monotonically and it can be used as an indicator of the senescence process also called "senescent spotting" of the banana peel. (c) 2007 Elsevier Ltd. All rights reserved.
- ItemDifferences Between the Order Model and the Weibull Model in the Modeling of the Enzymatic Browning(2016) Quevedo, R.; Díaz, O.; Valencia, E.; Pedreschi Plasencia, Franco; Bastias, J.; Siche, R.
- ItemEnzymatic browning in sliced and pureed avocado: A fractal kinetic study(ELSEVIER SCI LTD, 2011) Quevedo, R.; Ronceros, B.; Garcia, K.; Lopez, P.; Pedreschi, F.Modelling of browning is essential to evaluate the effectiveness of the processes applied to obtain fresh-appearance foods and also to determine their shelf life. Computer vision and the fractal kinetic method were used to quantify browning in three avocado cultivars. Samples (avocado slices and pur e) were stored at 4 degrees C and surface images were captured in the tiff format. Browning kinetic was derived from images using the L* mean method and the fractal method. In another experiment, inhibitor kinetic was also quantified, using the polyphenol oxidase activity method (in puree samples) with 0.1%, 0.5% and 1% of sodium bisulfite. In the results for avocado slices, kinetic rate derived by the fractal kinetic method was higher than that obtained with the L* mean method, but the opposite was observed when the avocado was pulping (avocado puree). Kinetic quantified by the fractal method was similarly inhibited by bisulfite, when compared with the L* mean value or PPO activity value methods. In general, the fractal method can be used to record browning kinetic and to discriminate between avocado cultivars, initial structural state of the sample (slice or puree), or in experiments using browning inhibitors. (C) 2011 Elsevier Ltd. All rights reserved.
- ItemKinetic deterioration and shelf life in Rose hip pulp during frozen storage(2020) Quevedo, R.; Valencia, E.; Pedreschi Plasencia, Franco; Diaz, O.; Bastias Montes, J.; Siche, R.; Muñoz, O.