Grape Processing by High Hydrostatic Pressure: Effect on Use of Non-Saccharomyces in Must Fermentation

Abstract

Vitis vinifera (variety Tempranillo) grapes were pressurized at 400 MPa by high hydrostatic pressure for 10 min and the effect on wild microbial populations, phenol extraction and wine composition was monitored. After treatment, the grapes were inoculated and fermented with Saccharomyces cerevisiae and several non-Saccharomyces yeasts: Schizosaccharomyces pombe, Torulaspora delbrueckii, Metschnikowia pulcherrima and Lachancea thermotolerans. S. pombe was used as sole fermentative yeast, but T. delbrueckii, M. pulcherrima and L. thermotolerans were used in sequential cultures with S. cerevisiae to completely ferment the sugars. The HHP treatment reduces strongly or eliminates wild microorganisms, especially yeasts, facilitating the growth and development of nonSaccharomyces yeasts. Thus, it helps to get either a better expression of enzymatic activities or metabolites production of nonSaccharomyces affecting wine quality.

Contribution of Non-Saccharomyces Yeasts to Wine Freshness. A Review

“…In the same way that yeast strains promote the formation of pigments, emerging preservation technologies for grape berries/must processing and winemaking could improve the colour in wines ( Figure 5). Such is the case of the high hydrostatic pressure (HHP) that increases total anthocyanins extraction and the formation of pyranoanthocyanins [73], especially the amount of vitisin A; the use Pinotins are pigments produced from the reaction of anthocyanins or pyranoanthocyanins with hydroxycinnamic acids or 4-vinyl phenols [69]; in this last case, the yeast strains with positive hydroxycinnamate decarboxylase activity can produce the intermediate compound that will condense via nucleophilic attack at position C4 of the anthocyanin structure [70]. Other pigments, mainly formed during the ageing period, comprise the previous formation of vitisins for further condensation with vinyl-flavan-3-ols and/or hydroxycinnamic acids or 4-vinyl phenols [71]; these reactions would produce the so called portisin-type pigments with bluish tonality due to an absorption at 570 nm [72] of the electromagnetic spectrum.…”

Emerging Technologies to Increase Extraction, Control Microorganisms, and Reduce SO2

“…The emerging technologies that showed the greatest potential for increasing the extraction of skin compounds and controlling indigenous microorganisms are as follows: high hydrostatic pressure (HHP) [4][5][6], ultra high pressure homogenization (UHPH) [7][8][9], pulsed electric fields (PEFs) [10][11][12][13][14][15], electron-beam irradiation (eBeam) [16][17][18], ultrasound (US) [15,[19][20], and pulsed light (PL) [21][22][23]. Most of these technologies are either approved or under evaluation as new enological practices in the International Organization of Vine and Wine (OIV) regulations [24][25][26].…”

“…Most non-Saccharomyces usually have lower fermentative power than S. cerevisiae or slower fermentation kinetics (e.g., Sp), which reduces the possibilities of being well implanted [40]. New emerging non-thermal technologies facilitate the use of non-Saccharomyces yeasts by eliminating or strongly reducing wild yeasts from the grapes [2,6,8,14,16,21].…”

“…Sporulated bacteria cannot be controlled by HHP because pressures around 1000 MPa are needed, which is not feasible for industrial equipment. The application of 200 MPa for 10 min on the grapes can decrease the indigenous yeast populations, with 400 MPa often being enough to eliminate the yeasts from the grapes [5][6]. However, even the treatment of 550 MPa for 10 min may not be able to completely eliminate bacterial populations [5].…”

“…However, even the treatment of 550 MPa for 10 min may not be able to completely eliminate bacterial populations [5]. The elimination of indigenous yeasts facilitates the implantation of inoculated non-Saccharomyces yeasts and the better expression of their metabolic activities [6]. Furthermore, the elimination of both wild yeasts and bacteria helps to reduce the levels of sulfites needed for their control.…”