Introduction to 2011 Student ML Trial

1. Introduction to 2011 Student ML Trial Linda F. Bisson Wine Flavor 101B March 23, 2012

2. The Malolactic Fermentation • Provides microbial stability to wine • Impacts wine flavor and aroma

3. Goals of Trial • Does the timing of addition of the ML inoculation impact success? • Does the ML strain make a difference?

4. Timing of Addition • If add early, bacteria can take advantage of nutrients like glucose and fructose. • If add early, bacteria may inhibit yeast metabolism and fermentation • If add early, yeast may inhibit bacteria • If add late, conditions will be more hostile to bacteria

5. Timing of Addition • There is no one correct answer • ML and yeast strain dependent • Influenced by juice composition

6. Strain Differences • Metabolite profile is strain dependent • Ability to persist in a marginal environment is strain dependent

7. The Experiment • Used Chardonnay Juice (pH 3.6; 22.4 Brix; TA: 5.76 g) • Cold settled, 72 hours, 2°C, racked, Nitrogen blanked stored at 2°C until used • Inoculated withEC1118 • No Sulfite before or during experiment • ML inoculated at three different times: • Simultaneous with yeast • During late fermentation • Post-fermentation

8. ML Strains Evaluated • Alpha • VP41 • 31 • Native ML

9. Conclusions • Fastest ML completion rates were noticed with juice inoculation • Timing of inoculation did not impact success of ML completion • Strain differences were noted, also in initial sensory experiments • The control ML underwent ML in about two months.

10. ML Tasting • Glass 1: Alpha, pre-fermentation • Glass 2: Alpha, mid-fermentation • Glass 3: Alpha, post-fermentation • Glass 4: VP41, post-fermentation • Glass 5: 31, post-fermentation • Glass 6: Control spontaneous ML