Abstract
Abstract Peroxidase (POD) and pectin methylesterase (PME) from tomato were characterized, studied thermal stability, and analyzed the synergistic effect of temperature and pH. For POD, the optimal activity, using H2O2 as substrate and ABTS+• as the donor H+, was obtained at pH 3.5, and for PME, the optimal activity using pectin as substrate was obtained at pH 7.5. In POD, it was found that the values of KM, Vm and Ksi for H2O2 were 477.26 mM, 721.53 µM/min and 0.37 mM, respectively. In PME, the values of KM and Vm obtained for pectin were 0.54 mM and 436.12 µM/min, respectively. On the other hand, it was found that POD was inactivated with 90 °C, at pH from 2.5 to 3.5 with temperatures of 55 to 90 °C, and at pH of 2.5 to 3 with temperatures of 40 to 90 °C. Likewise, PME was inactivated at 90 °C, and at pH of 3.5 with 70 °C.
Highlights
The tomato (Solanum betaceum) is a small shrub, belonging to the family of the solanaceous (Do-Nascimento et al, 2013)
The objective of this work was to extract, characterize, study the thermal stability, and synergistic effect of temperature and pH, for POD and pectin methylesterase (PME) in tomato puree, to study the best conditions of treatment to maximize the quality and minimize the organoleptic, nutritional and economic loss induced by enzymatic degradation
For PME, it was found that the optimal pH was 7.5, similar to that obtained in apple (Denès et al, 2000), banana (Ly-Nguyen et al, 2002a), kiwi (Pal et al, 2016) or carrot (Ly-Nguyen et al, 2002b), and lower to acerola (De Assis et al, 2002)
Summary
The tomato (Solanum betaceum) is a small shrub, belonging to the family of the solanaceous (Do-Nascimento et al, 2013). The fruit presents a great potential for the market due to its nutritional and organoleptic characteristics (Andrade et al, 2013; Márquez et al, 2007; Lagos et al, 2013), being fundamental for the juice and vegetable beverage industry (Rodríguez et al, 2011). Browning damage and loss of stability caused in fruit and vegetable tissues during postharvest treatment and processing is one of the main causes of loss of quality in juices and vegetable beverages. Peroxidase and pectin metilesterasa, responsible for a multitude of alterations in the parameters organoleptic of fruits and vegetables (Anthon et al, 2002; Núñez-Delicado et al, 2007), may be associated with losses in color, odor, taste, texture and nutritional values in juices and vegetable beverages (Cabanes et al, 2007)
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