Browsing by Author "Ronceros, B."

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    Color 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.
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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.