Grape juices made using small-scale production techniques are widely consumed. The extraction procedures employed to produce them, however, can affect bioactive compounds and antioxidant activity in the final product. In this study, juices prepared using four extraction methods (steam, extractor, juicer and blender) were evaluated for soluble and hydrolysable polyphenol content, total anthocyanin content, antioxidant capacity, physicochemical characteristics and colour. Acceptance of steam-extracted juices and their stability during storage were also evaluated. Steam extraction resulted in a higher soluble phenolic (1073 ± 58 mg gallic acid L−1) and anthocyanin content (138 ± 22 mg cyanidin L−1), as well as a higher antioxidant capacity when compared to juices prepared using other methods. Although steam-extracted juice remained microbiologically stable during 24 months of storage, changes in phytochemical compounds and antioxidant capacity did occur. Our results indicate that steam-extracted grape juices have high commercial potential.
Juices prepared using four extraction methods were evaluated. Steam extraction resulted in higher soluble phenolic and anthocyanin contents and higher antioxidant capacity when compared to juices prepared using other methods. Although steam extracted juice have remained microbiologically stable during storage for 24 months, changes in phytochemical compounds and antioxidant capacity occurred mainly throughout the first five months.