Submitted to: Food Science and Biotechnology
Publication Type: Peer reviewed journal
Publication Acceptance Date: 7/23/2005
Publication Date: 8/3/2006
Citation: Zheng, Y., Wang, S.Y., Wang, C.Y., Zheng, W. 2006. Changes in strawberry phenolics, anthocyanins, and antioxidant capacity in response to high oxygen treatments. Food Science and Biotechnology. 40:49-57. Interpretive Summary: Increasing evidence has shown that diets rich in fruits and vegetables may reduce the risk of some types of cancer and other chronic diseases. The main reason for the health benefits of fruits and vegetables is because they contain abundant amount of chemical called antioxidants. However, little information is available on the changes of antioxidant levels in fresh produce after harvest and how to maintain or increase these levels by using postharvest techniques. Antioxidant content can decline rapidly after harvest due to mishandling. We treated strawberry fruit with high concentrations of oxygen immediately after harvest and found that high oxygen not only maintains antioxidant values in strawberries, but concentrations higher than 60% also promoted the increases in other desirable compounds in the fruit. In addition, high oxygen also retarded decay of berry fruit during storage. Therefore, it is possible that the health benefits and the shelf-life of these berry fruit can be improved by postharvest exposure to high oxygen. This information is useful to the berry marketing industry and beneficial to consumers.
Technical Abstract: Changes in fruit quality, decay, phenolic and anthocyanin content, and antioxidant capacity of strawberries (Fragaria × ananassa Duch. cv. Allstar) stored under air and high oxygen atmospheres at 5ºC were investigated. Freshly harvested strawberries were placed in jars and ventilated continuously with air or with 40, 60, 80, or 100% oxgyen at 5ºC for up to 14 days. Samples were taken initially, and after 3, 7, 10 and 14 days of storage. While fruit quality parameters such as titratable acidity, total soluble solids and surface color were only slightly affected by differing levels of oxygen, the higher oxygen concentration treatments significantly reduced decay. Oxygen concentrations higher than 60% also promoted increases in ORAC values, total phenolics and total anthocyanins as well as individual phenolic compounds analyzed by HPLC during the initial 7 days of storage. However, this effect diminished with prolonged storage. No significant differences in ORAC values, total phenolics, total anthocyanins, or the individual phenolic compounds were observed among the high O2 and air stored fruits after 14 days of storage. These results indicate that high oxygen treatments may improve the fruit quality and antioxidant capacity of strawberry fruit only in the first 7 days of storage.