Stabilization of white grape must by application of supercritical CO₂ as a strategy to reduce the SO₂ content

Chemical Engineering and Food Technology Department, Wine and Agrifood Research Institute (IVAGRO), University of Cadiz, Puerto Real, 11519 Cadiz, Spain

Abstract

Winemaking worldwide, and especially the one carried out in warm climates, is looking for strategies to prevent enzymatic and microbial alterations of must and wines alternative to SO₂ addition. However, there is any methodology as efficient as SO₂, being used in combination with those substances in the best of cases, which does not suppose a real solution to the problem. In search of safer alternatives to preserve enological products, high-pressure treatments using supercritical CO₂ can be a sustainable alternative The aim of this study is to analyze the biocidal effect, and enzymatic inactivation of supercritical CO₂ on white grape must (Pedro Ximenez variety), in order to reduce SO₂ in the pre-fermentative stage. It was processed by varying the main variable of the process, the percentage of CO₂ (10, 40, and 70%), keeping the rest of the variables constant (100 bar, 35 ºC 10 min). Results are very promising and any of the treatment conditions seem to alter the physicochemical characteristics of must. Regarding must stabilization, this technique has proven to be very efficient in the reduction of total microorganisms, as well as reduce enzymatic activity of polyphenol oxidase, showing better results than those obtain when using SO₂.