Berries Full of Antioxidants

EDMONTON - Mar 3/08 - SNS -- Bush fruits like black currants and saskatoon berries produce substantially higher levels of antioxidant activity in humans than what is commonly reported for blueberries, says Chris Neeser, research scientist with Alberta Agriculture and Food, Brooks.

"The fact that saskatoons had even higher antioxidant activity than black currants was unexpected as this fruit is not known to contain high concentrations of phenolics or other antioxidants. The results from this survey will help scientists to quantify the variability of chemical characteristics relevant to the processing and marketing of black currants and saskatoons and their contributing value to human health."

Survey results did show that antioxidant activity varied considerably between samples, with coefficients of variance ranging from 11% to 26%. Grouping of the data by cultivar or region of origin did not account for this variability. However, the analysis of geographic, climatic, edaphic, and biological variables did provide some answers. The survey results showed that antioxidant activity was often higher in orchards that had more degree-days and more precipitation. On the other hand, antioxidant activity in saskatoons tended to be higher at lower elevations.

"While the anthocyanin content and composition for black currants and saskatoons was consistent with published values," says Neeser, "the results showed that one of the five black currant cultivars, Ben Sarek, had significantly lower anthocyanin levels. It was also found that warmer locations with average annual rainfall in the 450 mm to 500 mm range were most likely to have high anthocyanin content."

The vitamin C content in black currants was quite variable, but within the range reported in literature. Besides a highly significant difference between years, the analysis provided little further insight into what variables determined the vitamin C content.

"The results confirmed that black currant seeds contain 20 to 23% oil on a dry weight basis, and that close to 15% of this oil is gamma linolenic acid," says Neeser. "This means that black currant fruit is one of the best and perhaps most economical sources of this valuable omega-6 fatty acid. It was also found that the highest oil content was found in fruit grown on sites with an average of 160 to 170 frost-free days.

"In many cases, geographic and environmental variables can account for a significant portion of the variance in produce grown in different orchards. The information presented in the full report should be useful in decision-making regarding the location of new orchards."

This research survey was headed by Alberta Agriculture and Food and undertaken in collaboration with Olds College School of Innovation through funding from the National Science and Engineering Research Council.