Browsing by Author "Quevedo, R."

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    Correlation 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.
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    Determination 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.
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    Differences 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.
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    Enzymatic 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.
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    Kinetic 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.