Resposta antioxidante enzimática, respiratória e fisiológica do tomate-cereja (Solanum lycopersicum var. cerasiforme) submetido ao choque térmico

Abstract

Post-harvest treatments with thermal shock have been studied as an extension of alternative technical life of fruit. The beneficial effect of this technique has been related to their effects on the induction of physiological responses in protection against oxidative stress and development of pathogens. Enzymes are catalysts of the reactions occurring in biological systems. However, although the mechanisms by which post-harvest treatments induce this type of response are known in the plant organs are not clearly elucidated the mechanisms induced by postharvest heat shock that may affect the antioxidant status of treated fruits. The objective of this study was to evaluate the effect of heat shock on postharvest cherry tomatoes conservation, mediated biochemical and physicochemical answers related to antioxidant enzyme activity, respiratory activity, phenolic compounds, ascorbic, soluble solids acid, titratable acidity , percentage of weight, firmness, skin color and degradation of the fruit. The cherry tomatoes were subjected to heat shock treatments immersed in hot water at 45 ± 2 ° C at times 0, 5, 10, 15, 20 and 25 minutes. After treatments, fruits were divided into two groups. The first group was stored at 20 ± 2 ° C and at intervals of 1, 3, 6, 9 and 12 days, samples were taken and subjected to color analysis, firmness, weight loss, total phenolics, total flavonoids acid ascorbic acid and total soluble solids. The second group was submitted to respiratory activity assessments, ethylene production and enzymatic activity of superoxide dismutase, catalase and ascorbate peroxidase, at time intervals of 0, 2, 6, 24 and 48 hours of storage at 20 ± 2 ° C. According to the results, the fruits treated with heat shock suffered greater respiratory stress from the sixth day of storage. There was no significant difference between treatments for firmness, maintaining the rigidity of the fruit even after 12 days, and all treatments exhibited fruits with greater weight loss compared to the control. The application of heat treatment did not alter the total soluble solids content to the 6th day, heat exposure times of 15 and 20 min had a greater effect on the content of phenolic compounds during storage. exposed to heat fruits expressed the higher flavonoid content than the control and showed no recovery or increase in the concentration of ascorbic acid of cherry tomatoes in response to heat shock treatments that could indicate suppressive effect to stress. Thus, despite having the ability to prolong the life of cherry tomato, reducing the loss of the fruit after storage was not favorable for their use to reduce costs to prolong their shelf life