Presentation on theme: "Pre-Bottling Quality Control"— Presentation transcript:
1 Pre-Bottling Quality Control Molly KellyEnology Extension SpecialistPennsylvania Winery Association Annual MeetingMarch 3, 2014
2 Bottling and Packaging One of the most critical steps in wine productionMany opportunities for problemsPeople with different responsibilitiesMultiple wines to bottleOperation and maintenance of multiple equipment stations
3 QA and QCQuality Assurance (QA) focuses on attempts to improve and stabilize production practices in order to prevent defectsQuality Control (QC) focuses on product testing to uncover defectsHACCP: means of assuring quality, through the identification and monitoring of critical control points from vine to glass
4 Pre-bottling checklist Chemical analysisDoes wine meet proper criteria for bottling?Stability analysisProtein, bitartrate, color and microbiological stabilitySensory analysisMaterialsPresent and in proper condition?
5 Oxidation PotentialReview your bottling system (including pre-bottling filtration) to know the extent of oxygen pick-upOptimally, the oxygen pick-up during any transfer, including bottling, =< 0.2 mg/LOxidation potential can be minimizedParticulates, case dust, adsorb air (oxygen) -increase the potential for oxidative degradationThe 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 pHHow much is based on the wine’s biological content, wine chemistry, and how much free sulfur dioxide is lost during your bottling operationExcessive oxygen pick-up during the filtration and bottling, including lack of a vacuum system, reduces the sulfur dioxide concentration notably
7 Stability TestingThis commonly includes protein, bitartrate and microbiological testingA quantitative test for L-malic acid (vs. paper chromatography) will help assure that wines do not undergo MLF in the bottleIf 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 bottleHigh SO2 levels at bottling and cool storage will reduce the chances of this happeningSterile filtration can remove all bacteria and yeast
9 Wines with residual sugar Can measure with Clinitest tabletsStore under cool conditions (below 50F) to avoid stimulating yeastPotassium sorbate can help prevent refermentationNot 100% effective and can impart a bubblegum flavor to wine
10 Turbidity TestingIf a wine is not brilliantly clear, it will likely plug membrane filtersWines that do not clarify naturally should be tested for pectins and/or glucansPolysaccharides can inhibit clarification, fining and filtrationLab test: acidulated alcohol precipitationUse of pectolytic enzymes and/or glucanases
11 Sensory EvaluationTo be a true evaluation of structural, textural and aromatic elements, proper serving temperature and optimal glassware should be usedPrior to bottling a screen for sulfur like off-odors should be conducted on all wines
12 SanitationAnything in contact with the wine is a potential vector for microbial spoilageHave appropriate sanitation protocols in place and implement them
13 Sterile bottling rooms? Not an absolute necessityBottling area should be screened-off from fermentation areas and excessive air movementEasily sanitized floors, walls and ceilings
14 Sources of contamination at bottling Filter pad drip trays: drain often during runsFill bowls: leaky spouts. Mist filler spouts with 70% ethanol to inhibit microbial growthCorker: likely to have spilled wine so large source of contamination. Dismantle and clean before and after. Ethanol misting of corker jaws during bottlingActivity: increased worker activity in bottling area increases spread of airborne microbes. Limit number of people around filling/corking area
15 Bottling Quality Control Wine OxidationBottling can result in 0.5 to >2.0mg of oxygen per liter into the wineImpacts wine quality and shelf lifeTo limit oxygen issues:Sulfur dioxide adds prior to bottlingNitrogen spargingCarbon dioxide or nitrogen flushing bottles before filling
16 Loss of Free Sulfur Dioxide Is proportional to dissolved oxygen contentIf 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 oxygenSo an additional 5-6 mg of free SO2 is needed to reduce oxygen in the head space
17 Sulfur dioxideAcetaldehyde formation is a direct result of oxygen exposureMonitoring 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 upA periodic evaluation of the free sulfur dioxide level from random bottles is an effective gauge for monitoring wine development
18 Sulfur DioxideAs 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 minimizedWhen the free sulfur dioxide level drops to less than about 13 mg/L, we can expect perceptible “developed” and/or oxidative aromasA 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 CorksGenerally, corks transported at 20o C should be stored below 8% moistureWater activity is low enough to inhibit mold growthTreat corks with sulfur dioxide or purchase treated corksSuppliers 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 lenticelsIn a 750-mL bottle, several tenths of a cubic centimeter of oxygen can be released during the first weeks of bottle agingHow 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 BottlingHow much is desirable, and how much is excessive? More than 1.0 mg/L oxygen at bottling is not desirable for any wineLower concentrations are best for aromatic whitesRed wines, due to their higher buffering capacity, can withstand higher oxygen concentrations at bottling, up to about 0.7 mg/LFactors 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 oxygenHigh 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/LNatural cork mg/LThus, oxygen ingress post-bottling is usually very limited, or near zeroThe exceptions include some synthetic closures
25 Managing oxygen ingress Nitrogen gas sparging pre- and/or post-fillingLiquid nitrogen sparging pre- and/or post-fillingVacuumMost oxygen quality control strategies only record dissolved oxygen in the wine, leaving headspace levels unmonitored
26 Headspace managementInternational Wine Challenge in London: almost half of wine faults were oxygen management relatedAWRI Commercial Service and Normacorc: bottling line audit using PreSens® technologyPreSens technology and wine bottle application (PreSens/Nomacorc, 2008).Normacorc/AWRI Commercial Service
27 Oxoluminescence technology: headspace O2 and dissolved O2 Practical winery and vineyardOxoluminescence technology: headspace O2 and dissolved O2
28 Filter integrity Perform frequent pressure holds Bubble point CUNO Minicheck (a 3M company)Hand held deviceAttach to housing and pressurize for certain time framePass/fail
30 Bubble PointThe bubble point test detects minor filter defects and out-of-size pores and correlates with the bacteria passage.Sartorius.comMillipore.comMillipore.comFlood membrane with waterPressurize to 80% with Nitrogen gasIncrease 2psi/minNote pressure when bubbling starts and compare to filter specifications
31 Continuous in-line monitoring Sample directly through MicropreSure® monitor via sanitary sampling valveRemove excess liquid remaining in dome with syringeInsert 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 finishDecide where hazards can occurPut in controls and monitor themWrite it all down and keep recordsEnsure that it continues to work effectivelyAll wineries would benefit from a basic outline32
33 What about mobile lines? Photo courtesy of Jennifer Foil
36 ReferencesBottling 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 andVineyard.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.