The effect of an enzymatic digestion process on strawberry antioxidant capacity

Strawberry represents the most important berry in the Mediterranean diet. It is the most consumed berry as both fresh and processed products, the most studied berry from the agronomic, genomic and nutritional point of view, and it is also a remarkable source of micronutrients and phytochemicals with a relevant biologically activity on human health. Although individual bioactive compounds present in strawberries have been studied for their biological activities, the mechanisms by which they are metabolized and exert their beneficial effects on human health are still unknown. For this reason, the first objective of this research is the development of an enzymatic in vitro system which simulates the gastrointestinal conditions that occur in vivo during the digestive process. Briefly, the method consists on an initial pepsin-HCl digestion for simulating gastric conditions (pH~1.7) followed by an intestinal digestion with pancreatin and bile salts through a dialysis membrane. The dialysates were concentrated under vacuum, resuspended in H2O2/glacial acetic acid and purified with a C-18 SepPaks Vac 6 cc cartridge. The strawberry cultivar chosen for the study is 'Romina', one of the most promising cultivars developed in the context of the European Euberry project. The total antioxidant capacity of both the fresh fruit and the digested fraction was tested through the DPPH, FRAP and TEAC assays. The results obtained have shown a significant variation in the antioxidant capacity of 'omina', before and after the enzymatic digestion process. Significant decreases were found in all the performed assay, highlighting how the antioxidant capacity present in fresh fruit is drastically reduced following digestion. Further studies are required to elucidate the mechanisms of transport and metabolism of these compounds, with the aim of providing predictive results on their bioavailability and thus their effect on human health.