| Popis: |
The study was accomplished to optimize the application of stress treatment to prevent chilling injury (CI) in tomatoes. Four treatments were evaluated: control, heat shock applied for 24 (HS24) and 48 h (HS48), and cold shock applied for 24 h (CS24). The fruits were stored at 2 and 14C, and evaluated immediately after treatment and after 21 and 28 days of storage. An additional evaluation after 7 days of exposure at 20C following storage withdrawal was included to induce ripening and exteriorize the development of CI symptoms. Different biochemical and quality attributes were evaluated (color, titratable acidity, firmness, ethylene, CI index and heat shock protein [HSP] accumulation). Heat treatments were successful in preventing the decay of fruits under CI-inducing conditions. The significantly better performance of HS48 in comparison to the other treatments gives evidence that the effectiveness relies on the adequate intensity of application; therefore, this intensity should be strictly controlled by a proper monitoring method. In this regard, small HSP accumulation was found suitable to reflect properly the physiological condition of fruits and therefore to potentially optimize and determine the adequate intensity of treatment application. Practical Applications Stress treatments constitute a promising technological alternative to extend the shelf life of fruits and vegetables because of their capacity to prevent the development of chilling injury during the cold storage of sensitive species. The main advantages are the ease of use, considering that they can be applied in commercial chambers with minor changes, and the avoidance of chemicals. By assessing the effectiveness of treatments and the suitability of different biochemical and quality attributes as monitoring parameters to maximize the efficiency of application, it became apparent that the adequate intensity of application must be accurately established, since beyond a certain limit, the effect of the stress may induce irreversible alterations, provoking a permanent damage. The study provides evidence that small heat shock protein accumulation constitutes suitable monitoring parameters to objectively establish the optimal intensity, able to maintain the quality characteristics and extend the shell life of tomatoes during the cold storage. |
