Quality Assessment of Grape Juice Produced with a Semi-Industrial Steam Extractor Designed to Reduce Juice Dilution by Separate Collection of Condensates

The quality of grape juice (Vitis vinifera L. cv. País) obtained with a prototype steam extractor designed to reduce juice dilution by separate collection of condensates was evaluated and compared with conventional steam extracted and hand-pressed juice. The prototype extractor consistently outperformed the conventional system by better preserving the chemical quality of the fruit and ensuring greater stability during storage, producing grape juices with superior physicochemical characteristics, including total soluble solids and titratable acidity similar to hand-pressed juice. While initial concentrations of total phenolics were equal for both steam extracted juices, total anthocyanins, total flavonoids, and antioxidant capacity were substantially higher than in both conventional steam extracted and hand-pressed juice. During storage, the prototype-extracted juice showed minimal changes in key quality parameters from 1 to 3 months. Overall, this study demonstrates that the steam extractor design reduces juice dilution while improving stability and functional quality of the resulting grape juice.