Instant Controlled Pressure Drop as a Strategy To Modify Extractable and Non-extractable Phenolic Compounds: A Study in Different Grape Pomace Materials

Instant controlled pressure drop (DIC) is a technology able to modify the polyphenol profile in vegetal materials. However, information about how polyphenols are transformed, particularly regarding non-extractable polyphenol (NEPP), as well as the association with the initial content of polyphenols of the material is scarce. Thus, this work aimed to evaluate the DIC effect, modifying the pressure (0.2 and 0.4 MPa), the number of cycles (2 and 4), and grape pomace material (Malbec, Merlot, and Syrah) on extractable polyphenol (EPP) and NEPP contents. The EPP content increased during DIC application, an effect associated with the pressure, cycles, and initial polyphenol content. While for extractable and non-extractable proanthocyanidin contents, the main factors explaining the DIC effect are the pressure and number of cycles. Therefore, changes in polyphenols from grape pomace by DIC treatment are dependent upon experimental conditions, but the origin of the grape pomace also influences the extraction of EPP.