1. Pre-Bottling Quality Control
Molly Kelly
Enology Extension Specialist
Pennsylvania Winery Association Annual Meeting
March 3, 2014

2. Bottling and Packaging
One of the most critical steps in wine production
Many opportunities for problems
People with different responsibilities
Multiple wines to bottle
Operation and maintenance of multiple equipment stations

3. QA and QC
Quality Assurance (QA) focuses on attempts to improve and stabilize production practices in order to prevent defects
Quality Control (QC) focuses on product testing to uncover defects
HACCP: means of assuring quality, through the identification and monitoring of critical control points from vine to glass

4. Pre-bottling checklist
Chemical analysis
Does wine meet proper criteria for bottling?
Stability analysis
Protein, bitartrate, color and microbiological stability
Sensory analysis
Materials
Present and in proper condition?

5. Oxidation Potential
Review your bottling system (including pre-bottling filtration) to know the extent of oxygen pick-up
Optimally, the oxygen pick-up during any transfer, including bottling, =< 0.2 mg/L
Oxidation potential can be minimized
Particulates, case dust, adsorb air (oxygen) -increase the potential for oxidative degradation
The use of vacuum corkers, closure types, fill height, and the temperature of the wine at bottling impact the oxygen pick-up

6. Chemical analysis Sulfur dioxide
The concentration of free sulfur dioxide that provides an anti-microbiological impact is determined by the pH
How much is based on the wine’s biological content, wine chemistry, and how much free sulfur dioxide is lost during your bottling operation
Excessive oxygen pick-up during the filtration and bottling, including lack of a vacuum system, reduces the sulfur dioxide concentration notably

7. Stability Testing
This commonly includes protein, bitartrate and microbiological  testing
A quantitative test for L-malic acid (vs. paper chromatography) will help assure that wines do not undergo MLF in the bottle
If there is a potential for Brettanomyces growth, a biological screening should occur

8. Wines with malic acid Paper chromatography
If malic acid is present it will be susceptible to MLF in the bottle
High SO2 levels at bottling and cool storage will reduce the chances of this happening
Sterile filtration can remove all bacteria and yeast

9. Wines with residual sugar
Can measure with Clinitest tablets
Store under cool conditions (below 50F) to avoid stimulating yeast
Potassium sorbate can help prevent refermentation
Not 100% effective and can impart a bubblegum flavor to wine

10. Turbidity Testing
If a wine is not brilliantly clear, it will likely plug membrane filters
Wines that do not clarify naturally should be tested for pectins and/or glucans
Polysaccharides can inhibit clarification, fining and filtration
Lab test: acidulated alcohol precipitation
Use of pectolytic enzymes and/or glucanases

11. Sensory Evaluation
To be a true evaluation of structural, textural and aromatic elements, proper serving temperature and optimal glassware should be used
Prior to bottling a screen for sulfur like off-odors should be conducted on all wines

12. Sanitation
Anything in contact with the wine is a potential vector for microbial spoilage
Have appropriate sanitation protocols in place and implement them

13. Sterile bottling rooms?
Not an absolute necessity
Bottling area should be screened-off from fermentation areas and excessive air movement
Easily sanitized floors, walls and ceilings

14. Sources of contamination at bottling
Filter pad drip trays: drain often during runs
Fill bowls: leaky spouts. Mist filler spouts with 70% ethanol to inhibit microbial growth
Corker: likely to have spilled wine so large source of contamination. Dismantle and clean before and after. Ethanol misting of corker jaws during bottling
Activity: increased worker activity in bottling area increases spread of airborne microbes. Limit number of people around filling/corking area

15. Bottling Quality Control
Wine Oxidation
Bottling can result in 0.5 to >2.0mg of oxygen per liter into the wine
Impacts wine quality and shelf life
To limit oxygen issues:
Sulfur dioxide adds prior to bottling
Nitrogen sparging
Carbon dioxide or nitrogen flushing bottles before filling

16. Loss of Free Sulfur Dioxide
Is proportional to dissolved oxygen content
If not using vacuum fillers, corkers or flushing bottles with gas…up to 5 ml of air in bottle head space (750ml-1.4 mg of oxygen)
4 mg of sulfur dioxide are needed to neutralize effects of 1 mg oxygen
So an additional 5-6 mg of free SO2 is needed to reduce oxygen in the head space

17. Sulfur dioxide
Acetaldehyde formation is a direct result of oxygen exposure
Monitoring the free sulfur dioxide concentration could be an effective means of reviewing the impact of different closures and how a wine bottled with a certain closure is holding up
A periodic evaluation of the free sulfur dioxide level from random bottles is an effective gauge for monitoring wine development

18. Sulfur Dioxide
As wines develop in the bottle and retain a level of free sulfur dioxide exceeding 13 mg/L, the likelihood of developing oxidized aroma/flavors is minimized
When the free sulfur dioxide level drops to less than about 13 mg/L, we can expect perceptible “developed” and/or oxidative aromas
A level of 13 mg/L or more free sulfur dioxide should be considered an average concentration. Different wines have differing oxidative buffering capacities (impacted by the total antioxidant concentration)
Antioxidants include phenols, ascorbic acid, sulfur dioxide, etc.

19. Corks
Generally, corks transported at 20o C should be stored below 8% moisture
Water activity is low enough to inhibit mold growth
Treat corks with sulfur dioxide or purchase treated corks
Suppliers usually treat with SO2 gas or ionizing radiation

20. Cork Questions Are the corks bleached?
What is the moisture content when shipped?
How are they sterilized?
Do they remain sterile in your cellar?

21. Oxygen in the Bottle Can be highly variable
When the cork is compressed in the neck of the bottle, gas pressure in the cork cells can double, releasing oxygen trapped in the lenticels
In a 750-mL bottle, several tenths of a cubic centimeter of oxygen can be released during the first weeks of bottle aging
How much oxygen depends on several factors: including relative moisture content of the cork. The higher the cork moisture, the less oxygen is released

22. Oxygen at Bottling
How much is desirable, and how much is excessive? More than 1.0 mg/L oxygen at bottling is not desirable for any wine
Lower concentrations are best for aromatic whites
Red wines, due to their higher buffering capacity, can withstand higher oxygen concentrations at bottling, up to about 0.7 mg/L
Factors influencing oxygen levels at bottling include wine temperature, bottling equipment, and closure type.

23. Oxygen If potential for oxidation is high, do not bottle cold
Increased solubility of oxygen
High oxygen levels are especially detrimental to wines with sorbic acid (potassium sorbate)
Develop oxidative products that are unpleasant

24. Oxygen Penetration An example of oxygen penetration in closures:
Screwcaps mg/L
Natural cork mg/L
Thus, oxygen ingress post-bottling is usually very limited, or near zero
The exceptions include some synthetic closures

25. Managing oxygen ingress
Nitrogen gas sparging pre- and/or post-filling
Liquid nitrogen sparging pre- and/or post-filling
Vacuum
Most oxygen quality control strategies only record dissolved oxygen in the wine, leaving headspace levels unmonitored

26. Headspace management
International Wine Challenge in London: almost half of wine faults were oxygen management related
AWRI Commercial Service and Normacorc: bottling line audit using PreSens® technology
PreSens technology and wine bottle application (PreSens/Nomacorc, 2008).
Normacorc/AWRI Commercial Service

27. Oxoluminescence technology: headspace O2 and dissolved O2
Practical winery and vineyard
Oxoluminescence technology: headspace O2 and dissolved O2

28. Filter integrity Perform frequent pressure holds Bubble point
CUNO Minicheck (a 3M company)
Hand held device
Attach to housing and pressurize for certain time frame
Pass/fail

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30. Bubble Point
The bubble point test detects minor filter defects and out-of-size pores and correlates with the bacteria passage.
Sartorius.com
Millipore.com
Millipore.com
Flood membrane with water
Pressurize to 80% with Nitrogen gas
Increase 2psi/min
Note pressure when bubbling starts and compare to filter specifications

31. Continuous in-line monitoring
Sample directly through MicropreSure® monitor via sanitary sampling valve
Remove excess liquid remaining in dome with syringe
Insert broth medium via the dome and remove excess media with syringe. Incubate the MicropreSure® monitor.
Does not eliminate need for spot-checking bottles. Contamination can result downstream, especially at bottle filler.
Millipore Corp.

32. HACCP Logical system of control based on the prevention of problems
Look at your process from start to finish
Decide where hazards can occur
Put in controls and monitor them
Write it all down and keep records
Ensure that it continues to work effectively
All wineries would benefit from a basic outline 32

33. What about mobile lines?
Photo courtesy of Jennifer Foil

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35. Thank you for your attention.
Questions?

36. References
Bottling handbook for proper closures. Cork Quality Council, Forestville CA. Accessed Feb 26, 2013.
Lansing, R. May Managing Bottling Operations. Wine Business Monthly.
Neradt, F Sources of reinfections during cold-sterile bottling of wine. Am. J. Enol. Vitic. Vol. 33. no. 3.
Pilone, G Technical Note. Continuous inline monitoring of wine for yeast and bacteria. Am. J. Enol. Vitic. Vol 28, no. 4.
Pregler, B. Dec What’s Cool: Accurate Membrane Filter Integrity Testing.
Wine Business Monthly.
Tracy, R. and Skaalen, B. Jan/Feb Bottling-last line of microbial defense. Practical Winery and
Vineyard.
Ugliano, M., et al Controlling oxygen at bottling to optimize post-bottling development in wine. Practical Winery and Vineyard.
Zoecklein, B. January 13, Enology Notes #97. Virginia Tech Wine and Grape Chemistry Group.
Zoecklein, B. February 17, Enology Notes #98. Virginia Tech Wine and Grape Chemistry Group.
Zoecklein, B. January 30, Enology Notes #111. Virginia Tech Wine and Grape Chemistry Group.