Evaluating the benefits and problems associated with malolactic fermentation of Merlot wines
Emma Bruwer, 16122364, BSc Agric (Viticulture and Oenology), J.H Neethling Building, Victoria Street, Stellenbosch University.
Rudi Scholtz, Thelema Mountain Vineyards, Helshoogte Pass, Stellenbosch.
August 2015
ABSTRACT
Malolactic fermentation is the conversion of harsh and acidic malic acid to a more desirable form of lactic acid in wine by Lactic acid bacteria, after the completion of alcoholic fermentation. This reaction can take place naturally in wine, proving to be very unpredictable and not always favourable, or by inoculation with bacterial cultures. Malolactic fermentation (MLF) is mostly found in barrel aged red or white wines. For this experiment the differences between spontaneous and inoculated MLF on barrel aged Merlot wines were explored. Analysis was taken of the grapes at harvest and during the vinification process; sensory evaluation was also used to analyze the aroma contribution to the wine. Two different blocks were treated as a duplicate treatment, and results found the inoculated wine completed MLF faster, producing less volatile acidity along with the increased production of …show more content…
Sulphur dioxide (total and free) analysis was carried out using the Metrohm titration unit (Metrohm Ltd., Switzerland). Malolactic fermentation in the wine was monitored by obtaining the malic- and lactic acid concentrations on a regular basis (at the start of MLF and every seven days thereafter) until its completion (taken as the point when the malic acid concentration is equal to or lower than 0.3 gIL). This was done by Fourier-transform Infrared Spectroscopy (FT-IR) (WineScan FT120, FOSS Analytical, Denmark) as well as determination of the malic acid concentration with an enzymatic assay (Roche, Boehringer Mannheim,
Emma Bruwer, 16122364, BSc Agric (Viticulture and Oenology), J.H Neethling Building, Victoria Street, Stellenbosch University.
Rudi Scholtz, Thelema Mountain Vineyards, Helshoogte Pass, Stellenbosch.
August 2015
ABSTRACT
Malolactic fermentation is the conversion of harsh and acidic malic acid to a more desirable form of lactic acid in wine by Lactic acid bacteria, after the completion of alcoholic fermentation. This reaction can take place naturally in wine, proving to be very unpredictable and not always favourable, or by inoculation with bacterial cultures. Malolactic fermentation (MLF) is mostly found in barrel aged red or white wines. For this experiment the differences between spontaneous and inoculated MLF on barrel aged Merlot wines were explored. Analysis was taken of the grapes at harvest and during the vinification process; sensory evaluation was also used to analyze the aroma contribution to the wine. Two different blocks were treated as a duplicate treatment, and results found the inoculated wine completed MLF faster, producing less volatile acidity along with the increased production of …show more content…
Sulphur dioxide (total and free) analysis was carried out using the Metrohm titration unit (Metrohm Ltd., Switzerland). Malolactic fermentation in the wine was monitored by obtaining the malic- and lactic acid concentrations on a regular basis (at the start of MLF and every seven days thereafter) until its completion (taken as the point when the malic acid concentration is equal to or lower than 0.3 gIL). This was done by Fourier-transform Infrared Spectroscopy (FT-IR) (WineScan FT120, FOSS Analytical, Denmark) as well as determination of the malic acid concentration with an enzymatic assay (Roche, Boehringer Mannheim,