Bioaccessibility of bioactive compounds and antioxidant activity in murta (Ugni molinae T.) berries juices

Abstract

The aim of the study was to characterize the bioactivity and storability of a steam juicer extract from murta (Ugni molinae T.) berries, comparing with the bioactive quality of the fresh fruit. An extraction assay was performed at three different processing times and quality of the extract was assessed by determining bioactives content, antioxidant activity after processing and during storage at different temperatures (5, 20 and 35 degrees C). Total polyphenols, total anthocyanins and antioxidant activity in fresh fruits and juice extracts were evaluated as bioaccessible fractions during an in vitro gastric-intestinal digestion process. Weibull distribution was applied to model the storage behavior of the extracts, and fitted well to experimental data on degradation kinetics of bioactive phenolics and antioxidant activity. The best processing times for highest extraction of bioactive phenolics were found to be 28 +/- 1 min for frozen-thawed and 34 +/- 1 min for fresh fruits. The juice extract can retain around 80% of the polyphenols and anthocyanins after 21 days of storage at 5 degrees C. The bioaccessibility index of polyphenols in fresh murta berries or in juice achieved a relatively high value of 70% at the end of the small intestine digestive step. However, the bioactives in the bioaccessible fractions of the fruits and juices had significantly different behavior during the gastric-intestinal digestion steps. The juice released the bioaccessible bioactives in the earlier gastric stage, while the fresh fruit unfolded a higher antioxidant activity with increased release of bioactives in the small intestine.