1. Effects of Inoculation Level During and After Fermentation

2. Student Team Meredith Bell, Sarah Harper, Joanne Oh, Diego Roig and Luke Bohanan

3. Fermentation Analysis Diego Roig

4. Goal of Study To compare the effect of different levels of inoculation of active dry commercial yeast preparations on fermentation and sensory characteristics of wine Used Chardonnay juice and Premiere cuvee

5. 2010 UC Davis Chardonnay Crushed and Pressed 9/2/10 Healdsberg crusher destemmer Bucher Vaslin Press Juice held in cold storage news.ucdavis.edu

6. 2010 UC Davis Chardonnay Split into six, 10 gal drums Inoculated 10/8/10 Premier cuvee 6 inoculation levels skolnik.com

7. Inoculation Levels Lot123456 Yeast (g)0g0.0080.258.0g80.0g140g Cells/ml 010 3 10 4.5 10 6 10 7 1.8x10 7 Chemistry of Juice: Brix: 25.25; pH3.66; TA 4.98 (g/L) NOPA: 56; Ammonia:132; YAN: 188

8. Fermentation Cold fermentation cellar Brix and Temp taken twice daily When Dry, moved to cold storage

10. Rate of Fermentation Inoculation Level Inoculation size directly effects the rate of fermentation Larger initial biomass Less time/energy spent on achieving maximum cell density (2 x 10 8 cells/mL) despite lower maximum growth rate

11. Temperature Temperature is important component of any fermentation. Premier cuvee yeast has temp. range of 7- 35°C Chardonnay temps were b/w 12-18°C, with no irregular heat spikes

12. Temperature Highest temperatures throughout study seen in natural fermentation despite slowest rate of fermentation Max. temp. (natural fermentation): 17.9°C Max. temp. (inoculated fermentations): 17.2- 17.3°C Possible explanations Heat generation during yeast budding Different yeast strain dominating fermentation Closer to warmer area of room (not likely)

13. DateBlend ID% EtOHpHTA (g/L)VA (g/L) 11/15114.93.825.780.40 11/15214.73.826.070.44 11/15314.93.835.710.44 11/15415.73.825.790.33 11/15515.43.736.230.27 11/15614.93.726.680.35 Lab Analysis of the Finished Wine

14. 123456 10/292-3%1- 1.5% TraceTrace - Neg Neg 11/52%1%0.5%TraceNeg 11/12Trace0.5- 1% TraceNeg Results of the Residual Sugar Testing

15. Chemical Analysis Ethanol Inhibition Inoculation levels shown to increase EtOH tolerance Current study confirms previous findings. Slower rates of fermentation at lower inoculation levels possibly due to decreased EtOH tolerance of yeast

16. Chemical Analysis Volatile Acidity Lower VA measurements at higher inoculation levels Acetobacter repressed in absence of oxygen Lower VA measurements correlated to shorter lag phase? Different strains of S. cerevisiae produce varying amounts of acetic acid May explain lower measurement in Lot 1

17. Chemical Analysis pH/Titratable Acidity Malolactic fermentation results in increase in pH and decrease in TA Slower fermentations saw pH increase and decrease in TA Possible that ML fermentation began? Colder temps inhibit ML, Lots 5/6 moved to cold room 2 weeks sooner than rest of Lots

18. Sensory Analysis Luke Bohanan

19. Sensory Evaluation Acceptance test with hedonic scale Aroma only 2 Repetitions all wines Randomly numbered Randomly ordered Judge tracking

20. Mean Preference Scores Reasonable Variance Two Distinct groups Outliers…

21. ANOVA XLSTAT used Judges H 0 rejected = Not all Judges scored the same Wines H 0 rejected = Not all wines were scored the same Reps H 0 accepted = No significant difference between reps

22. Judge Grouping From LS Mean D C B A

23. Wine Grouping from LS Mean C B A

24. Preference Mapping Judges in tight group compared to wines Drastic difference in wine grouping

25. Mean Factor Score from PCA Wines 5 and 6 are disliked Wines 1-4 are liked Wine 4 is liked the most

26. What does sensory tell us? Highest concentration of desired aroma compounds at 10 6 cells/ml Higher concentration of undesirable compounds at 10 7 cell/ml and above Concentrations below 10 6 cells/ml show acceptable levels of desirable aromas

27. Possible causes of negative aromas Treatment 5 and 6 left on mass of lees = reductive environment = sulfur Lack of nutrients Post fermentation contamination Headspace post fermentation = O 2 Exposure

28. Questions?