Capturing nutraceuticals on film
Chitosan carries vitamins and minerals to enrich fruit.
As the year progresses, thoughts of summer naturally spring to mind. If you dream of garden parties with bowls laden with fresh strawberries and cream, the chances are that you will not be thinking about the nutritional content of the fruit. However, a team of US food scientists is trying to make strawberries even better for you and claims to have developed a coating for the fruit that can enhance levels of vitamin E or calcium.
To deliver the compounds, Su-Il Park and Yanyun Zhao from Oregon State University, US, turned to chitosan, an abundant and renewable biopolymer found in the cell walls of fungi. The polymer has excellent film-forming and antifungal properties and is sometimes used as a semi-permeable coating material for fresh fruits and vegetables to help extend shelf-life.
The Oregon team made chitosan films containing a high concentration of vitamin E or calcium and tested them on fresh strawberries and raspberries. The researchers claim that the coatings not only improved the storage of the fruit, delaying the change in colour and pH, but also increased the content of calcium and vitamin E in both fresh and frozen fruit. Park and Zhao now intend to try to incorporate other compounds, such as minerals, vitamins and fatty acids, into the films.
According to Zhao, a commercial food company is currently testing the coatings.
S-I Park and Y Zhao, J. Agric. Food Chem., 2004, 52, 1933