Freeze-Drying of Wine Yeasts and Oenococcus oeni and Selection of the Inoculation Conditions after Storage

Ale CE Otero MC
2015 Journal of Bioprocessing & Biotechniques  
Fermentative properties; Glycerol synthesis freeze-drying conditions and using lyoprotective agents [9] [10] [11] [12] . In addition, taking into consideration a potential large-scale production of the dry starter products, the choice of the lyoprotective agents and of the storage conditions would diminish production costs and guarantee a more practical way of inoculation. The available data on freeze-drying involves mainly pure cultures of S. cerevisiae strains used in AF in wines and beers
more » ... wines and beers [10, 11, [13] [14] [15] and O. oeni [16, 17] , but there is no information about the freeze-drying of non-Saccharomyces yeasts in pure or mixed cultures with S. cerevisiae strains plus O. oeni. S. cerevisiae mc 2 , K. apiculata mF and O. oeni X 2 L were previously selected for their ability to grow and metabolize sugars in simultaneous cultures under winemaking conditions, thus improving glycerol production and therefore the organoleptic properties of the endproducts [18] . In this work, we evaluated the resistance of the selected wine microorganisms in pure and mixed cultures to the lyophilization process and the maintenance of both viability and metabolic activity (AF, MLF and glycerol production) when powders were stored at different temperatures. Abstract Modern winemaking industry has new challenges focused on the application of preserved starter's microbial cultures for the optimization of the fermentation process that ensuring flavor characteristics and the reproducibility of the final products obtained. Thus, the aim of the present work was to select the inoculation conditions for preselected Saccharomyces cerevisiae mc 2 (SC), Kloeckera apiculata mF (KA) and Oenococcus oeni X 2 L (OO) after freeze-drying and storage in both pure and mixed cultures. The strains were grown in 17% Natural Grape Juice (NGJ) and then lyophilized in 10% individual sugars (glucose, fructose, sucrose, maltose and trehalose), 2.4% sodium glutamate, 4% yeast extract and NGJ by using different culture combinations: 1)-pure cultures (KA1, SC1, OO1), 2)-mixed yeast cultures (KA2, SC2), 3)-mixed microbial cultures (KA3, SC3, OO3). After lyophilization, the strains were stored for 12 months at 4 and 25°C. Viability post-lyophilization was culture/lyoprotectant-dependent while survival to storage depended on time and temperature being O. oeni the more resistant strain to the all process, then K. apiculata and S. cerevisiae, respectively. Freeze-drying of mixed KA-SC in 10% fructose and OO in 17% NGJ up to 6 months of storage at 4°C were the best conditions for the maintenance of the fermentative properties of the strains and for glycerol production. The inoculation of grape musts with KA-SC and OO lyophilized individually with low-cost lyoprotectants would ensure the proper development of the fermentation processes and glycerol synthesis, thus increasing the organoleptic characteristics of wines by a non-Saccharomyces strain. Therefore, the starter culture should include K. apiculata, S. cerevisiae and O. oeni strains. Citation: Ale CE, Otero MC, Pasteris SE (2015) Freeze-Drying of Wine Yeasts and Oenococcus oeni and Selection of the Inoculation Conditions after Storage. J Bioprocess Biotech 5: 248
doi:10.4172/2155-9821.1000248 fatcat:2h6dbl5vergldgh4aa2bghydza