Production of Bottle-Fermented Sparkling Wine Using Yeast Immobilized in Double-Layer Gel Beads or Strands

Abstract

Bottle-fermented sparkling wines were produced using <i>Saccharomyces cerevisiae</i> immobilized within double- layer calcium-alginate beads or strands, and some factors affecting the leakage of viable cells from the gel into the wine during fermentation and aging were investigated. Yeast immobilized in beads or strands at 10⁴, 10⁶, or 10⁸ cells/mL was added to 740-mL samples of a base wine containing 24 g/L sucrose, at ethanol concentrations of 0.5%, 3%, 6%, 9%, or 12% (v/v). Secondary fermentation was conducted at 15°C or 25°C in 770-mL bottles with a pressure gauge. Fewer free yeast cells appeared in the wines the higher the initial number of immobilized cells or the initial ethanol concentration. Wines fermented with yeast immobilized in gel beads contained greater numbers of yeast cells than those immobilized in gel strands, but no free viable yeast cells remained in the wines a few months after fermentation in either case. Beads would be preferable to strands in commercial production because they were much more easily added to and removed from bottles via the ice disgorging procedure commonly used in the production of Champagne, without the need for the traditional riddling. Sparkling wine was also made using freely suspended yeast, and changes in the chemical components, including amino acids, during aging of wines made with free and immobilized yeast were investigated and compared. There were no significant chemical differences between the two. It was thus concluded that secondary fermentation of sparkling wines using yeast immobilized within double-layer alginate beads is practical for commercial production.