Simultaneous Alcoholic and Malolactic Fermentations by Saccharomyces cerevisiae and Oenococcus oeni Cells Co-immobilized in Alginate Beads

Abstract

Malolactic fermentation (MLF) usually takes place after the end of alcoholic fermentation (AF). However, the inoculation of lactic acid bacteria together with yeast starter cultures is a promising system to enhance the quality and safety of wine. In recent years, the use of immobilized cell systems has been investigated, with interesting results, for the production of different fermented foods and beverages. In this study we have carried out the simultaneous immobilization of Saccharomyces cerevisiae and Oenococcus oeni in alginate beads and used them in microvinifications tests to produce Negroamaro wine. The process was monitored by chemical and sensorial analyses and dominance of starters and cell leaking from beads were also checked. Co-immobilization of S. cerevisiae and O. oeni allowed to perform an efficient fermentation process, producing low volatile acidity levels and ethanol and glycerol concentrations comparable with those obtained by cell sequential inoculum and co-inoculum of yeast and bacteria cells in free form. More importantly, co-immobilization strategy produced a significant decrease of the time requested to complete AF and MLF. The immobilized cells could be efficiently reused for the wine fermentation at least three times without any apparent loss of cell metabolic activities. This integrated biocatalytic system is able to perform simultaneously AF and MLF, producing wines similar in organoleptic traits in comparison with wines fermented following traditional sequential AF and MLF with free cell starters. The immobilized-cell system, that we here describe for the first time in our knowledge, offers many advantages over conventional free cell fermentations, including: (i) elimination of non-productive cell growth phases; (ii) feasibility of continuous processing; (iii) re-use of the biocatalyst.

Microbial Resources and Innovation in the Wine Production Sector

“…Bleve et al, 2016). This is mainly due to the numerous advantages that cell immobilisation offers, including enhanced fermentation productivity, feasibility of continuous processing, avoidance of microbial contamination, starter cell stability and recycling (García-Martínez et al, 2015).…”

“…Many different carriers have been proposed for the immobilisation of yeasts and bacteria for wine making, including inorganic and organic materials, mainly polysaccharides, and natural products such as cellulosic materials, cereal grains and pieces of fruit (e.g. Servetas et al, 2013;Bleve et al, 2016 With reference to yeast immobilisation, the use of corn grains (Kandylis et al, 2012) as supports for S. cerevisiae immobilisation was found to be efficient during both ambient and low-temperature fermentation processes. These systems showed good operational stability during repeated batch fermentations of grape must, even at extremely low temperatures.…”

“…The biocatalyst was effective for simultaneous, low-temperature (10°C) wine fermentations. Bleve et al (2016) carried out the simultaneous immobilisation of S. cerevisiae and O. oeni in alginate beads and used them in microvinification tests to produce Negroamaro wine. Co-immobilisation of S. cerevisiae and O. oeni allowed an efficient fermentation process to be performed, producing low levels of volatile acidity and ethanol and glycerol concentrations, comparable with those obtained by cell sequential inoculum and co-inoculum of yeast and bacteria cells in free form.…”

Yeast Immobilization Systems for Alcoholic Wine Fermentations: Actual Trends and Future Perspectives

“…In this way, Servetas et al (2013) co-immobilized S. cerevisiae and O. oeni in DCM carriers covered with starch gel composite and observed a high efficiency at low temperature fermentations (10°C) obtaining a wine characterized by an increased ester formation and lower higher alcohols. Bleve et al (2016) co-immobilized the same microorganisms in Ca-alginate beads revealing an efficient performance of Negroamaro must fermentation with a decrease of the time needed to complete AF and MLF, low production of volatile acidity and similar organoleptic traits of the wine obtained than with those using sequential AF-MLF in free cell formats. The yeast and bacteria cells immobilized were reused up to three times with no activity loss.…”

“…By using the same carrier, S. cerevisiae and lactic acid bacteria Oenococcus oeni were confined to operate simultaneously AF and MLF with the purpose of enhancing safety and quality of wine ( Servetas et al, 2013 ; Bleve et al, 2016 ). In this way, Servetas et al (2013) co-immobilized S. cerevisiae and O. oeni in DCM carriers covered with starch gel composite and observed a high efficiency at low temperature fermentations (10°C) obtaining a wine characterized by an increased ester formation and lower higher alcohols.…”