Biotechnological Approach Based on Selected Saccharomyces cerevisiae Starters for Reducing the Use of Sulfur Dioxide in Wine.

Angela Capece,Patrizia Romano,Rocchina Pietrafesa,Gabriella Siesto

doi:10.3390/microorganisms8050738

Abstract

Sulfites are considered the main additives in winemaking for their antimicrobial, antioxidant and anti-oxidasic activities. The current concern about the potential negative effects of sulfur dioxide (SO2) on consumer health has focused the interest on replacing or reducing SO2 use. Our work aims to develop a strategy based on the use of selected starter culture, able to perform wine fermentation without SO2 addition. Four selected Saccharomyces cerevisiae indigenous strains were tested as mixed starter cultures in laboratory scale fermentations. The starter culture, characterized by a similar percentage of dominance of both strains composing the mixed starter and able to produce a wine characterized by the best combination of chemical and aromatic characteristics, was chosen. This mixed culture was tested as a starter at pilot scale with and without SO2 addition, by using a higher inoculum level in the vinification without SO2. The selected starter confirmed higher dominance ability in vinification without SO2 addition than in SO2-added fermentation, demonstrating that sulfite addition is not a guarantee to reach an absolute dominance of starter culture on indigenous microflora. The proposed biotechnological tool allowed to produce good quality wines possessing also “functional properties”, as NO-SO2 added wines were characterized by high polyphenol content and antioxidant activity.

Highlights

The antioxidant and antimicrobial action of sulfur dioxide (SO2) is well known, being commonly used in many processed foods for hundreds of years [1], especially in low pH foods, such as grape must
The four selected S. cerevisiae strains were tested at laboratory scale fermentations as mixed cultures, in which they were inoculated in co-cultures one with the other in different combinations (Figure 1), in comparison to single starter of each strain
In the first step of the research activity, four selected wild S. cerevisiae strains were tested as mixed starter cultures, in order to select the most suitable strain combination for fermentation without sulfur dioxide addition

Summary

Introduction

The antioxidant and antimicrobial action of sulfur dioxide (SO2) is well known, being commonly used in many processed foods for hundreds of years [1], especially in low pH foods, such as grape must. SO2 addition prior to the onset of alcoholic fermentation exerts a selective antimicrobial activity against spoilage yeasts, by inhibiting their growth and promoting the rapid development of Saccharomyces cerevisiae. Due to these properties, winemakers considered sulfur dioxide indispensable, but the current concern about the potential negative effects of excessive amounts of this compound in wine on organoleptic quality and consumer health, has focused the interest on minimizing the amounts of SO2 in grape must and wine. The total sulfur dioxide content cannot exceed 150 mg/L and 200 mg/L in red and white wines, respectively, whereas organic red and white wines cannot contain more than 100 mg/L and 150 mg/L [4]

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