The effects of storage temperature, storage duration, hydro-cooling, and micro-perforated wrap on shelf life of broccoli (Brassica oleracea L., Italica Group)
Peter M. A. Toivonen
Postharvest Biology and Technology Vol: 10 Issue: 1, January 1997, Pages 59-65.
1997
บทคัดย่อ
This work was initiated to determine the effects of cold storage duration and storage temperature on the shelf life of wrapped broccoli when subsequently placed into elevated temperatures to simulate retail shelf conditions. In addition, the effect of hydro-cooling prior to wrapping was evaluated. These tests were designed to test the potential for micro-perforated wrap in extending shelf life of broccoli under varied postharvest handling conditions. In the first experiment, broccoli (Brassica oleracea L., Italica Group; cv. Mariner) was harvested and the crop divided into 4 treatments; (1) `hydro-cooled + no wrap', (2) `hydro-cooled + wrap', (3) `non-cooled + no wrap', and (4) `non-cooled + wrap'. Samples of each of the 4 treatments were removed from storage after 3 days at 1°C and placed into 13°C to simulate shelf conditions. Visual quality, weight loss and respiration were monitored over 5 days at 13°C. This shelf evaluation was repeated with broccoli samples that had been stored for 10 and 17 days at 1°C. In a second experiment, broccoli was harvested and hydro-cooled. Half the crop was wrapped with micro-perforated film and the other half left unwrapped. From these two treatments, half of the heads were stored at 1°C and the other half at 5°C. After 10 days, all the heads were placed at 13°C for 5 days. Measurements at 13°C were taken as in the first experiment. In the first experiment, for broccoli which was stored for only 3 days at 1°C, the use of either hydro-cooling or wrap gave good firmness retention at 13°C shelf conditions. However, for broccoli which had been stored for 10 or 17 days, both hydro-cooling and wrapping were required to achieve the best firmness retention. Yellowing during the 5 days at 13°C was found to be the greatest for broccoli that had been stored at 1°C for only 3 days. Broccoli stored for 10 and 17 days developed much less yellowing during 5 days holding at 13°C. In the second experiment, storage at 1°C resulted in much better shelf life than storage at 5°C. Application of wrap gave best firmness retention and least water loss, independently of storage temperature. Only colour retention was affected by storage temperature, with 5°C storage resulting in a significant increase in yellowing. Neither hydro-cooling nor packaging had an effect on yellowing. Therefore, broccoli firmness and colour retention can be easily maintained for 5 days at elevated `shelf' temperatures with the integration of a system which includes hydro-cooling, application of micro-perforated film wrap and sufficient cold storage duration at 1°C.