Influence of coinoculation of L. plantarum and O. oeni on the color and composition of Tempranillo wines

Abstract

AIM: The aim of this research was to determine the influence of performing malolactic fermentation (MLF) of Tempranillo wines by coinoculation with Lactobacillus plantarum or Oenococcus oeni and Saccharomycescerevisiae on the composition and color of the final wines in comparison with sequential inoculation with Oenococcus oeni and spontaneous MLF.

METHODS: Around 1500 Kg of Tempranillo grapes from Pagos de Anguix winery (Anguix, AOC Ribera de Duero, Spain) were harvested at the optimal maturity. Grapes were destemmed, crushed and placed in twelve 200-L tanks to perform 4 different experimental conditions by triplicate. Three tanks were coinoculated with O. Oeni and S. cerevisiae, 3 with L. plantarum and S. cerevisiae whereas the other 6 tanks were inoculated only with the same strain of S. cerevisiae. Once alcoholic fermentation was finished 3 of these tanks were inoculated with O. oeni while the other 3 were maintained for spontaneous MLF. Once MLF were finished all the wines were sulphited and racked to 100-L plastic tanks (Flexcube, Quilinox) with oxygen permeability similar to oak barrels. Two months later the wines were analyzed: standard parameters, acids (enzymatic methods), colour (CIEL*a*b*), anthocyanins (spectrophotometry and HPLC), tannins (methyl cellulose and phloroglucinolysis-HPLC). Wines were also tasted by a trained panel.

RESULTS: All the wines submitted to coinoculation finished MLF at the same time that alcoholic fermentation. Wines submitted to sequential inoculation finished MLF around 20 days later while wines submitted to spontaneous MLF needed around 40 days. All coinoculated wines had significant higher titratable acidity and lactic acid concentration, especially those coinoculated with L. plantarum, than wines from sequential inoculation or spontaneous MLF. Moreover, all the wines from coinoculation had more intense colour and higher total phenolic index (TPI) than the other wines.

CONCLUSIONS:

These results confirm that coinoculation with both species of lactic acid bacteria, or L. plantarum, are an interesting tool to favour MLF and consequently shorten the waiting times associated with conventional malolactic fermentation. Moreover, it seems that coinoculation has other complementary and interesting effects on wine acidity, colour and phenolic compound composition.