Lucía Polo

Biogenic amine synthesis in high quality Tempranillo wines. Relationship with lactic acid bacteria and vinification conditions

Due to toxicological and economical concerns, there is considerable interest in establishing which enological practices promote biogenic amine accumulation in wines. Effects of SO2 and lysozyme, malolactic fermentation (MLF) management and ageing have been studied. The type of bacteria performing MLF and ageing proved to be the main factors influencing biogenic amine content of wine, specifically Tempranillo from Somontano appellation (Huesca, Spain), produced at an industrial scale. Sulphur dioxide and lysozyme, at the doses used, were not sufficient to reduce lactic acid bacteria populations. Treatments to inhibit MLF were not able to prevent histamine production. No relationship was found between the type of vessel in which MLF took place and subsequent biogenic amine content.

Immobilisation of yeasts on oak chips or cellulose powder for use in bottle-fermented sparkling wine

Sparkling wine production comprises two successive fermentations performed by Sacharomyces cerevisiae strains. This research aimed to: develop yeast immobilisation processes on two wine-compatible supports; study the effects of yeast type (IOC 18-2007 and 55A) and the immobilisation support type (oak chips and cellulose powder) on the fermentation kinetics, the deposition rate of lees and the volatile composition of the finished sparkling wine; compare the fermentation parameters of the wines inoculated with immobilised or non-immobilised cells. Proper immobilisation of yeast on oak chips and cellulose powder was demonstrated by electron microscopy. Total sugar consumption occurred in under 60 days in all bottles, regardless of the strain used and the way they were inoculated in wine. Deposition of lees was 3-fold faster in the bottles containing immobilised cells than in those with free cells; no addition of adjuvants was necessary. The analysis of the volatile compounds of the finished sparkling wines showed significant differences in the formation of esters, acids, alcohols, aldehydes and lactones according to the yeast and the immobilisation support used. Oak chips were the more appropriate support for yeast immobilisation. No significant differences in the sensorial analysis of the sparkling wines produced by the different strategies were found.