Health-promoting properties as a target for selecting strawberry cultivars in breeding programmes

Strawberries are among the most valuable fruits for fresh consumption in the world. Besides their pleasant taste, fruits are highly appreciated by consumers because of their health benefits, which have been related to the antioxidant capacity of the polyphenolic compounds they contain. However, strawberry cultivars present different amount and type of this antioxidants. This, joined to the fact that the digestion process can affect their release and alter their composition, could result in differences on the health effects (i.e., bioactivity; BA) of these cultivars, and therefore, it could be important to consider the digestion process for selecting a bioactivity indicator. Thus, the antioxidant capacity (TEAC) of the fruits of five strawberry cultivars was determined before (i.e., fresh fruit material) and after being subjected to an in vitro digestion process (i.e., digested fractions). Thus, on each cultivar, an effect of in vitro digestion was observed, decreasing the TEAC of potentially absorbed extracts (i.e., bioavailable; TEAC(BA)) with respect to the TEAC of the fruit (TEAC(F)), although the decrease in antioxidant capacity was not in the same proportion in all cultivars, there being no correlation between TEAC(F) and TEAC(BA). To evaluate the correlation between TEAC(BA) and its BA, a ROS (reactive oxygen species) quantification in hepatic cells treated with bioavailable extracts of two strawberry cultivars, previously selected for their higher and lower TEAC(BA), ('Marquis' and 'Primoris', respectively) was carried out, showing a higher BA in 'Marquis' (i.e., cultivar with higher TEAC(BA)). These results show the importance of performing the in vitro digestion process to reveal the health potential of strawberry cultivars. Besides, TEAC(BA) is proposed as an indicator of BA. However, for selecting parents in breeding programmes, more efforts must be done in order to find a BA indicator that can be determined by faster and more direct techniques.