“A combination of heat treatment followed by calcium (Ca) dip for controlling postharvest pests and/or diseases has had satisfactory results in maintaining or improving the texture of several products,” said authors Shirin Shahkoomahally and Asghar Ramezanian from Shiraz University, who published the study in the March 2015 issue of HortScience.
The researchers from the university’s Department of Horticultural Science treated mature, unripe kiwifruit (Hayward) with hot water for 5, 10 and 15 minutes at 47°C then dipped them in a 2% w/v CaCl2 solution and stored the kiwifruit at 0°C for up to 120 days. During storage, fruit were sampled at 0, 30, 60, 90 and 120 days for postharvest quality evaluation.
“Our analyses showed that fruit firmness decreased during cold storage, and the rate of decrease was significantly higher in control fruits compared with those treated with hot water and calcium treatments,” the authors said.
Results also showed that hot water and calcium treatments significantly suppressed colour development of kiwifruit stored at 0°C for 120 days compared with calcium-only treatments.
The report said this suggests that “hot water and calcium treatments have a potential to act as an alternative colour loss prevention method for long-term storage”.
Fruits dipped in hot water and calcium also showed a significant difference with respect to total phenolics, which was associated with lower polyphenol oxidase (PPO) activity. Heating combined with calcium dips significantly reduced PPO activity during 120-day storage.
The complete study and abstract are available on the ASHS HortScience electronic journal
