Influence of electric field intensity on to improvement of extraction of polyphenols during vinification of Garnacha grapes

MAZA MARCOS; ÁLVAREZ, IGNACIO; RASO, JAVIER

Workshop; 4th PEF School Vienna; 2017

Introduction. The effect of PEF to accelerate or increase the extraction of phenolic compounds during maceration-fermentation stead of red winemaking has been deeply investigated. However, most of these studies have been performed in batch treatments and in studies conducted in continuous process, the highest intensity assayed has been 4 kV/cm (Puértolas et al, 2012). The objective of this investigation was to check if the application of PEF treatment in continuous flow to the grapes of Garnacha increases the efficacy of the extraction of polyphenols during vinification of Garnache grapes. Materials and Methods. Monovarietal grape of Vitis vinifera var. Garnacha (Aragon, Spain) was manually collected (vintage 2016) in the appellation of origin Campo de Borja (Spain). PEF modulators used in this investigation were Modulator PG (ScandiNova, Uppsala, Sweden) for treatments in the range of 4 to 8 kV/cm and EPULSUS® PM1-10 (Energy Pulse Systems, Lisbon Portugal) for treatments in the range of 1 to 4 kV/cm. Grapes after destemming were treated in a colinear treatment chamber with two treatment zones of 2.5 cm of gap and 3.5 cm and of inner diameter at a flow of 400 kg/h in the conditions showed in the table. Maceration-fermentation was conducted in thanks of 100 L with 80 kg of grapes at 18ºC. Maceration for control sample were 4 (CS4) and 13 (CS13) days; for samples treated with the Modulator PG for 8 kV/cm (SCA8) and 6 kV/cm (SCA6) was 4 days; and for samples treated at 4 kV/cm (SCA4) and at 1 kV/cm (EPS1) and 4 kV/cm (EPS4) with was 6 days and NT2 was 13 days. Total polyphenols index (TPI), colour intensity (CI), total anthocyanins (ANT) and condensed tannins (TA) were analysed along maceration-fermentation.