An Integrated Approach of Hypobaric Pressures and Potassium Permanganate to Maintain Quality and Biochemical Changes in Tomato Fruits

Limited postharvest life of tomato fruit is due to its highly perishable nature. Hypobaric pressure is a new emerging hurdle technology usually used up to a pressure of 100 kPa for the preservation of fruits and vegetables. In this study, an integrated approach of hypobaric pressures (40 kPa and 50 kPa) and sponge-dipping of potassium permanganate (KMnO4) was designed for the postharvest life extension of tomato fruits. Fruits were treated with either 400 ppm of KMnO4, or 40 or 50 kPa hypobaric pressures, or their combination. Fruits without any treatment was considered as a control treatment. All groups were packaged in polypropylene trays as ready to retail and stored at room temperature at 25 ± 1 ℃ for 21 days. Basic quality parameters such as pH, total soluble solid, percent weight loss, percent spoilage, firmness, ethylene production rate, and color were evaluated at 3-day intervals. Results showed the application of hypobaric pressures and KMnO4, either alone or in combination, provided a synergistic effect in maintaining the quality compared to the control treatment during the 21 days of storage. The highest decay was found in the control compared to the combined treatments of KMnO4 + 40 kPa and KMnO4 + 50 kPa. Similarly, a decrease in firmness and color values was highest in the control treatment followed by the KMnO4 and 50 kPa hypobaric pressure compared to the combined treatment of KMnO4 + 50 kPa. In the same way, a high ethylene production rate was observed in the control, while the lowest ethylene production rate was found in KMnO4 + 50 kpa. Sensory evaluation indicated a highest score of 9 on the 9-point hedonic scale of tomato fruits. Among all groups, the combined application of 50 kPa hypobaric pressure + 400 ppm KMnO4 retained the best overall quality attributes compared to all other treatments throughout the experiment; therefore, this treatment could be applied at a commercial level for tomato fruits.