Carotenoids and cyanogenic glucosides in Saskatoon berries (Amelanchier alnifolia Nutt.)

The levels of carotenoids (lutein, zeaxanthin and beta-carotene) and cyanogenic glucosides (prunasin and amygdalin) were determined in saskatoon berries of five cultivars, picked at four stages of maturity, at four locations in Manitoba and Alberta, Canada. Lutein was found to be the predominant carotenoid in all the samples analyzed, and in mature (purple) berries ranged from a low value of about 300 to a high of 1000 mu g/100g of fresh berries. The corresponding values for zeaxanthin were 60-120 mu g/100g of fresh berries. Levels of lutein, zeaxanthin and beta-carotene were much higher in the green berries (48,000-146,000 mu g/100g, fresh weight (FW)) than in the more mature fruit. In mature fruit, the Smoky berries from Alberta had in general higher levels of lutein, zeaxanthin and beta-carotene than the other varieties. The occurrence of two cyanogenic glucosides, prunasin and amygdalin, was also established in all saskatoon berries analyzed. In all varieties, the levels of the two glucosides were very low in the green stage and then essentially the same for the following maturity stages. In mature (purple) berries the content of amygdalin ranged from 43 to 129 mg/kg of fresh berries, and the content of prunasin was 5-19 mg/kg FW. The presence of amygdalin in these berries is reported here for the first time. Crown Copyright (c) 2007 Published by Elsevier Inc. All rights reserved.