Abstract

Vitis vinifera L. cv. Pais is an ancestral Chilean grape undervalued due to its undesirable oenological characteristics. In this study, steam extraction for the production of grape juice, a new product, according to our knowledge, is proposed as an alternative for the valorization of this fruit. The effect of the extraction time on the composition and antioxidant capacity of Pais grape juice obtained was evaluated, as well as the change in the phenolic profile during storage. The soluble solid values and total polyphenol and total anthocyanin content increased with the extraction time. However, a residence time of the juice in the extraction device higher than 10 min led to thermal degradation of anthocyanins and flavonols. The most abundant phenolic compound identified and quantified by HPLC-DAD in the Pais grape juice was cinnamic acid. The storage of juices had a greater effect on anthocyanin and flavonol losses than the residence time of the juice in the extraction device. The antioxidant capacity of juice measured by ABTS and ferric reducing power assays ranged from 3 to 5 mmol trolox/L and from 10 to 18 mM Fe2+/L, respectively. In summary, steam extraction is a viable method to produce Pais grape juice with antioxidant capacity.