Nanoencapsulation systems to improve solubility and antioxidant efficiency of a grape marc extract into hazelnut paste

Encapsulation of a phenolic grape marc extract to enhance its lipid solubility and antioxidant efficiency for application as a natural preserving agent of hazelnut paste was investigated. Three nanoemulsion based encapsulation systems were tested: an oil/water nanoemulsion; a powder obtained by maltodextrin-assisted spray-drying of the previous and an ethanol/solid–lipid nanoemulsion (the third also applied to resveratrol for comparison). All the samples were mixed with hazelnut paste at different phenolic concentrations (from 1200 to less than 10 ppm of gallic acid equivalents for the original and encapsulated extracts, respectively). An accelerated shelf-life test at 60 °C was carried out until 59 and 98 days (for the original and encapsulated extracts, respectively) with peroxides value monitoring. Paste oxidation followed a first-order kinetics model and was significantly inhibited by extract addition. Encapsulation improved phenolic efficiency against lipid oxidation, by increasing extract dispersability in the paste and preserving the antioxidant activity, with the oil/water nanoemulsion resulting as the best system.

► A grape marc extract proved efficient in reducing hazelnut paste oxidation.
► Nanoemulsion based encapsulation improved phenolic efficiency against lipid oxidation.
► Oil/water nanoemulsion resulted as the best encapsulation system.
► Oxidation of hazelnut paste followed a first-order kinetics model.