Folate content in strawberries (Fragaria x ananassa): Effects of cultivar, ripeness, year of harvest, storage, and commercial processing

Folate concentrations in strawberries and folate retention during storage and commercial processing of strawberries were investigated. No previous study has focused on the effects of cultivar, ripeness, and year of harvest of strawberries with respect to the folate content. This study showed the folate concentration in strawberries to significantly depend on all of these different factors. Total folate was quantified using a modified and validated radioprotein-binding assay with external calibration (5-CH3-H(4)folate). Folate content in 13 different strawberry cultivars varied from 335 mug/100 g of dry matter (DM) for cv. Senga Sengana to 644 mug/100 g of DM for cv. Elsanta. Swedish harvests from 1999 and 2001 yielded higher folate concentrations than did the harvest from 2000, and the grade of ripeness affected the folate content in strawberries. This study indicated high folate retention in intact berries during storage until 3 or 9 days at 4 degreesC (71-99%) and also in most tested commercial products (79-103%). On the basis of these data fresh strawberries as well as processed strawberry products are recommended to be good folate sources. For instance, 250 g (fresh weight) of strawberries (similar to125 mug of folate) supplies similar to50% of the recommended daily folate intake in various European countries (200-300 mug/day) or 30% of the U.S. recommendation (400 mug/day).