Antioxidant effect of Stevia rebaudiana on inhibition of peroxidase and polyphenoloxidase from orange, mango and papaya.
Criado M. N., Belda-Galbis C. M., Martínez A., Rodrigo D.
Author Affiliation: Food Preservation Group, Department of Preservation and Food Quality, Instituto de Agroquímica y Tecnología de Alimentos (IATA-CSIC), Avda. Agustín Escardino, 7 Paterna, València 46980, Spain.
Post Harvest, Food and Process Engineering. International Conference of Agricultural Engineering - CIGR-AgEng 2012: agriculture and engineering for a healthier life, Valencia, Spain, 8-12 July 2012 : P-1878
Abstract : The antibrowning effect of Stevia rebaudiana (SR) water extracts on the activity of orange, mango and papaya peroxidase and polyphenoloxidase at 12 and 37°C was evaluated. For both enzymes, the degradation level was always higher at 37°C than 12°C, being POD more resistant to degradation than PPO. The inactivation of PPO and POD was strongly influenced by presence of stevia; the higher SR concentration (2.5%) caused the greater enzyme inactivation, in fact, incubation at 37°C with 2.5% SR reduced POD activity below method detection limit. Except for 1.5 and 2.5% of stevia at 37°C that PPO was more resistant to inhibitor, in the rest of analysis, POD showed less substrate specificity to this antibrowing. To complete our study, the experimental data (Log (A/A0)) as a function of storage time for each SR concentration and temperature were adjusted to Weibull inactivation model by nonlinear regression. Kinetic parameter a for each combination was obtained. For both enzymes, independently of storage temperature, a increased as stevia concentration increased and can therefore be considered an index to quantify the antioxidant capacity of SR. These results indicate that SR can be used as antibrowning agent to prevent fruit quality degradation.