Tag Archive | bottling

July Pre-Harvest Planning in the Cellar

By: Denise M. Gardner

If you are a wine producer in the northern hemisphere, harvest may feel quite far away.  However, given that it is now the month of July, it will be here before we all know it.

Harvest season is just around the corner! Photo by: Denise M. Gardner

The month of July is a great time to start preparing a few essential pre-harvest tasks including getting a bottling schedule ready, especially if bottling operations have not yet begun, and ordering harvest supplies.   This blog post will focus on these two tasks.

Prepare and Enact a Bottling Schedule

New grapes are about to flood your winery with juice and future wine.  Now is the time to review inventory within the cellar and determine what has to be moved and what has to be bottled before harvest begins.

Freeing up previous years’ inventory by moving it into bottle will free up tank, barrel and storage space for this year’s incoming fruit.  It makes for a much easier transition if all of the wines that need bottling are bottled before harvest season starts.  Bottling during harvest is not only chaotic, but it tires employees, pulls resources from the incoming product, and may lead to harvest decisions that may be regretted later.

Always make sure to get bottled wines properly stored and away from any “wet areas” on the production floor.  If possible, bottled wines should have a separated storage area within an ideal environment that is physically separated from production.  From there, stored wines can be moved into retail space when needed.

For more information on how to get wines prepared for bottling, please visit our previous posts:

Bottling comes with its own set of challenges and risks, but several analytical tests can help put a winemaker’s mind to ease regarding bottle stability. Photo by: Denise M. Gardner

Ordering Fermentation and Lab Supplies

Many suppliers and wine labs offer free shipping in July, which can especially be useful for wineries that are not geographically close to a winery supply store-front.  Planning ahead and determining what fermentation supplies will be needed in August, could save extra money.  Not to mention, having supplies on hand during the busy processing season can be a big stress relief.

Winemakers should also take the time to look at new fermentation products and assess the previous year’s needs in order to adequately supply for the up-and-coming harvest.  Keeping an annual inventory of purchases can be helpful to isolate regular needs.

Things to consider purchasing include:

  • Yeast
  • Fermentation Nutrients
  • Malolactic Bacteria
  • Enzymes
  • Yeast Hulls
  • Salts for Acid Adjustments
  • Tannins
  • Pectic Gums and/or Inactivated Yeast Products
  • Fining Agents
  • Oak Alternatives or Barrels
  • Sanitizing Agents

While new yeasts are released frequently, being constructive about the production’s fermentation needs can help isolate what yeasts are needed for the upcoming harvest.  I typically recommend that all vintners have at least 5 strains on hand for harvest: 2 reliable strains that will get through primary fermentation with little hassle, 1 strain that can be relied upon for sluggish or stuck fermentations, and 2 strains for specialty needs (e.g., sparkling or fruit wine/hard cider production) or experimental use.

Select and purchase your yeast strains in July to take advantage of free-shipping promotions. Photo by: Denise M. Gardner

Fermentation nutrients should be a must-have for all wineries to help minimize the risk of hydrogen sulfide.  Always double check nutrient requirements for yeast strains purchased.  In general, wineries will need hydration nutrients (e.g., GoFerm), complex nutrients (e.g., Fermaid K), and diammonium phosphate (DAP).

For more information on why YAN is important and how yeasts utilize nitrogen during primary fermentation, please visit the following blog posts:

If you need further step-by-step instructions on how to determine adequate nutrient additions during primary fermentation, please visit our Penn State Extension fact sheet: Wine Made Easy Nutrient Management during Fermentation

Sometimes hydrogen sulfide will arise in a wine by the time primary fermentation ends despite all preventative care.  Making sure there are adequate supplies on hand, such as copper sulfate and PVI/PVP can save time in the future.  Also make plans for ways that the production can reserve fresh lees.  PVI/PVP is a fining agent that can help reduce metals like residual copper, but fresh lees will also help reduce the perception of hydrogen sulfide aroma/flavor and residual copper in the wine.  Having a plan for retaining and storing lees during harvest season can save time during challenging situations that develop through the end of harvest and into the winter’s storage season.  A fact sheet on copper screens and addition trials can be found at the Penn State Extension fact sheet: Wine Made Easy Sulfur-Based Off-Odors in Wine.

I also like to make sure we have supplies on hand in case of heavy disease pressure come harvest.  This includes things like Lysozyme, beta-gluconase, pectinase or other clarification enzymes, and fermentation tannins.  Lysozyme can help reduce lactic acid bacteria levels while beta-gluconase can assist clarification problems associated with Botrysized wines.  For further information on how to manage high-disease pressured fruit, please visit the Penn State Extension website on Fermenting with Botrytis or Managing Sour Rot in the Cellar.

Double check the storage requirements for all materials purchased before and after the product is opened.   It’s important to store all of those supplies in the winery properly as it will ensure their efficacy by the time the product is needed.

Summer in the Cellar

By: Denise M. Gardner

As the growing season turns into full swing, now is the time to get things tidied up in the winery and prepare for this vintage’s harvest season.  The cellar offers the advantage of being relatively cool in the summer months, so it offers an oasis away from the beating sun or those rainy, humid days.  Managing some time for the up-and-coming harvest is a good way to keep cellar work current.  Otherwise, the summer months can appear rather dull in the cellar.  Here’s a list of considerations for the cellar crew:

Give your wines a regular analytical check

For anything that is sitting or aging in the cellar, now is a good time to schedule quality control monitoring.  Wines in barrel need regularly topped off (every other month or every other 2 months) and checked for free sulfur dioxide concentrations if they have completed malolactic fermentation (MLF).

There’s a lot of good information out there on sulfur dioxide.  If you feel slightly uncomfortable with sulfur dioxide additions or analysis, please refer to these current informational pieces that can be a valuable resource to any winemaker:

Wines that are getting ready to be bottled should go through a full analytical screen and recorded into the lab record books.  This will provide insight for the winemaker in terms of how the wine should progress or need altered prior to bottling:

  • pH
  • titratrable acidity (TA)
  • residual sugar
  • residual malic acid concentration and malolactic fermentation completion
  • free and total sulfur dioxide
  • cold stability
  • protein (heat) stability
  • volatile acidity (VA)
AO apparatus set up to measure free sulfur dioxide. Photo by: Denise M. Gardner, Penn State Extension Enologist

AO apparatus set up to measure free sulfur dioxide. Photo by: Denise M. Gardner, Penn State Extension Enologist

For more information pertaining to how to set up wine analysis in your winery, please refer to Penn State Extension’s website on “Starting a Lab in a Small Commercial Winery.”  Information on how to utilize analytical testing labs to the advantage of the winery can be found on the Penn State Extension website, “Wine Analytical Labs.”

For those wineries that have not previously measured cold stability, read Virginia Mitchell’s report on “Cold Stability Options for Wineries,” which explains the importance of testing and how to best treat your wines.

For more information on wine stabilization (sulfur dioxide additions, cold and heat stabilization), please refer to our previous blog post on “Stabilizing Wines in the Cellar.”

Get wines ready for blending or finishing

Now is a good time to pull samples of those wines that you are planning on bottling prior to harvest.  After getting a good analytical evaluation, make sure you check the wines for their sensory perception.  Is the wine at the caliber of quality that you were expecting?  If no, what can you do to fix the wine and get it ready for bottling?  Utilize fining agents or product additions to tweak the wines and enhance the quality.

Also consider blending.  Blending can be a tool to help mitigate problem wines.  But blending can also help you create a spectacular wine out of several great varietals.

Always remember to prepare bench trials before making changes to the entire tank or barrel of wine.  Make sure that several people evaluate the wine and give you their individual evaluation.  Have people write down their perceptions, as opposed to talking in a group, to avoid the power of persuasion and to minimize tasting insecurities.  This practice will give you a more honest, objective evaluation of the wine.

Prepare for Bottling

The summer months are the ideal time to get your wines bottled and ready for release.  Most wines need at least 2 to 6 months of bottle conditioning (i.e., time in the bottle before sale) to stabilize and minimize the effects of bottle shock.

Bottling is a time intensive process and requires a bit of planning by the cellar crew.  Prepare a calendar for bottling days to ensure that all supplies are received for bottling, that wines are fully ready to be bottled, and that there is adequate time to get everything bottled prior to the estimated start date of harvest.  For information pertaining to bottling considerations – how best to sanitize and monitor sterile filtration integrity – please refer to our previous blog post titled, “Bottling Tips and Considerations.”

Take Inventory

Now is a good time to go through all of the supplies that are currently available in the winery and record how much you have of each.  Recording inventory each year is a good way to evaluate what supplies are being purchased, what is being used, and what supplies are typically left over.  It is possible for wineries to find some redundancies through this exercise and identify places to save money.

Suppliers’ “Free Shipping in July” promotions are just a month away!  So being prepared with an accurate inventory can release some stress from the winemaker when it comes to ordering this season’s harvest supplies.  Things to consider include:

  • Yeast and Malolactic Bacteria
  • Yeast Nutrients
  • Any Enological Agents (e.g., Enzymes, Tannins, Polysaccharides/Inactivated Yeasts)
  • Fining Agents
  • Sugar and Acid
  • Potassium Metabisulfite
  • Cleaning and Sanitizing Agents

Make sure that all of the materials currently stored in the winery are being stored properly (i.e., dry chemicals away from wet chemical storage, food grade away from non-food grade, and the requirement that some may need stored frozen), according to the supplier’s recommendations, and that their expiration date has not expired.  For some expired products, some suppliers may be evaluating their efficacy of the product past the expiration date.  If you contact the supplier, you may be able to find an extended expiration date so that the product can be retained.  Otherwise, expired products should be thrown out and re-ordered.

Additionally, going through an equipment inventory can be advantageous.  Make sure all processing equipment is getting prepared to get a good cleaning and sanitizing regimen prior to the start of harvest.  Unused equipment should not be a storage vessel for left-over, dirty rice hulls or mouse droppings.  Use the summer months to check all of the equipment and make sure it is functioning properly.  If there are problems with equipment, it is best to identify it over the summer and, hopefully, get serviced before the start of harvest.  Don’t forget to check tank valves, pumps, inspect hoses for cleanliness, and all of the processing equipment.  Using an inventory, or check sheet, is a good way to ensure equipment is up to par is a good way to keep track of everything’s condition.  Also, evaluating barrel needs and tank space available for harvest can be added to the inventory sheet.

If you have a wine lab, now is also a good time to check the chemical and supply inventory in the lab.  Remember – free shipping in July is just around the corner!  Document expiration dates of chemicals and make a list of new chemicals, analytical standards, or equipment (e.g., hydrometers, pipettes, pipette bulbs, sampling bottles, etc.) that should be purchased prior to harvest.

Inventory all of your supplies to get prepared and organized for the upcoming harvest. Photo by: Denise M. Gardner, PSU Extension Enologist

Inventory all of your supplies to get prepared and organized for the upcoming harvest. Photo by: Denise M. Gardner, PSU Extension Enologist

Take time to evaluate and write SOP’s

Standard Operating Procedures, SOP’s, can help minimize the chaos during harvest.  Having up-to-date SOP’s in the cellar and lab will help minimize the number of times people will always have to ask “the boss” for help.

If you don’t have SOP’s, consider starting small and documenting protocols for things like lab analysis.  Plenty of resources (e.g., websites, text books) are available and can be used to create a standard protocol that works for your winery.

After tackling lab analysis, consider writing an SOP for harvest operations.  Think about writing an SOP for each piece of equipment that your harvest team will need trained on.  Take the crusher/destemmer for example:

  • How is the crusher/destemmer hooked up?
  • How to prepare the crusher/destemmer for fruit arrival (include cleaning and sanitizing procedures).
  • Do you have validation measures to ensure that the equipment is properly cleaned (a visual evaluation? Some sort of analytical testing?)?
  • Do you have a record system that documents the equipment has been properly prepared, cleaned, and sanitized?  If so, where is that documentation and how does your staff document this step?
  • What is the protocol for running the crusher/destemmer?  What safety features should all employees be trained on?  Document all safety procedures.
  • How is the crusher/destemmer cleaned and sanitized after each lot (varietal) of fruit that is run through the equipment?
  • How is the crusher/destemmer cleaned and sanitized after each processing day?  Where is the equipment stored and how is stored?

Winemakers can also document processing decisions.  For example, if you know that you are going to process Vidal Blanc every year, consider writing an SOP specific for how the Vidal Blanc is processed.  Write out each step, the quality control checks (i.e., checking fruit chemistry or monitoring fermentation) and what processing aids are typically added to the Vidal (e.g., yeast, enzymes, etc.).

Winemakers should also have an SOP ready for when fruit arrives to the winery in less than ideal conditions.  For information on what winemakers should consider, please read the two articles on Penn State Extension’s website titled “Producing Wine with Suboptimal Fruit.”

Botrytis disease pressure on Pinot Grigio grapes. Photo by: Denise M. Gardner

Botrytis disease pressure on Pinot Grigio grapes. Photo by: Denise M. Gardner

Having a fully functional and trained cellar crew is a good foot forward as the harvest months approach.  While preparation is tedious, it can save some time and resources during the busy harvest season… and hopefully, minimize the chaos!

Considerations and Tips for Wine Bottling

By: Denise M. Gardner

It’s bottling season!  Wineries are gearing up for the current growing season and another harvest.  Now is the crunch time to get everything from last year’s vintage out of tank and barrel, and into bottle.  Bottling is time intensive and tedious for a winery of any size, and it’s easy to leave the bottling line with contaminated wine bottles.

Bottling day in the Food Science Building, 2015

Bottling day in the Food Science Building, 2015

In fact, previous research has shown that even when sterile filtration steps are properly performed, over between 39-58% of the bottles leaving the bottling line end up with yeast in the bottle (Neradt 1982).  Renouf et al. (2007) found that using sterile filtration (0.45 micron absolute filter or lower) was the only way to eliminate most microorganisms from the wine during bottling.  However, in bottles that contained microbial populations upon bottling, Brettanomyces was able to bloom in the bottle after 6 months of storage, and increase 4-EP and 4-EG volatile phenol concentrations within 10 months post-bottling (Renouf et al. 2007).  In fact, long term storage of red wines infected with Brettanomyces found this spoilage yeast became the dominate microbial population in the bottle, outcompeting most other microorganisms (Renouf et al. 2007).  Yikes!

Bottling is one of the most important steps to retain wine quality at the winery.  Therefore, this blog post will focus on a number of bottling considerations for wineries:

  • Make pre-bottling additions before bottling day

Most product additions, including sulfur dioxide, potassium sorbate, gums, sugar, etc. require at least 24 hours of stabilization in wine before it can be sterile filtered and bottled.  There are some exceptions, and some products may require longer stabilization time or need to be added during bottling, after filtration.  You should rely on the advice of your product supplier when working with new additives.  Additionally, some filter suppliers recommend making large sugar additions to wine at least a week before filtration.

If you are making the final sulfur dioxide addition the day before bottling, make sure you measure the concentration of free sulfur dioxide in the tank prior to bottling.  Take multiple samples throughout the tank to ensure that the sulfur dioxide has penetrated all sections of the wine.  If the sulfur dioxide is not high enough to reach the 0.85 ppm molecular level, it is best to alter additions and wait to bottle another day.  For more information on sulfur dioxide additions at various wine pH’s, please click here.

  • Cleaning…

Whether you have a manual bottling and capping system, or a high-tech bottling line, physically cleaning the bottling line is essential to maintaining proper hygiene in the winery.  Bottling is one of the key areas where the quality of the product can greatly be degraded.  Have brushes specific for the bottling line, and utilize detergents that break down wine debris or environmental dust.

Some bottling lines will require personnel to remove valves, hose lines, etc. to physically clean off debris or biofilms.  Following cleaning operations, proper sanitation is essential to reduce microbial contamination through the bottling process.

*Note: The use of potassium sorbate will not inhibit contamination of your wine through bottling.  Only proper sanitation techniques can reduce microbial populations and minimize risk of microbial spoilage in the bottle.

  • …and Sanitation of the Bottling Line

As mentioned above, proper sanitation reduces microbial populations within food equipment and the surrounding environment, in order to reduce the risk of potential contamination within the packaged product – in this case, wine.  While greatly underestimated, the surrounding environment is a potential contamination point in wineries, especially during bottling.  Aseptic bottling operations are not necessary to maintain good hygiene, but it is often recommended that the bottling line be isolated within the winery to avoid large air movements while wine is packaged.  This helps to avoid yeast, which are ubiquitous, contamination during the bottling process.

Floors, walls, and drains should be easily accessible and cleaned in the bottling area to help reduce environmental contamination.  Routine environmental sanitation will also help reduce the risk of contamination.

Additional primary sources of contamination on the bottling line have previously been identified by Neradt (1982):

  1. Filler/Fill spouts
  2. Corker
  3. Bottle sanitizer
  4. Bottle mouth
  5. Filter
Capping a bottle of wine during bottling.

Capping a bottle of wine during bottling.

Proper sanitation of the bottling line first requires proper cleaning to remove all physical dirt and debris.  Otherwise, the sanitation step is literally “cleaning dirt.”

Water chemistry, temperature, and contact time all affect the efficacy of sanitation.  The use of soft water is often recommended for sanitation to avoid hard water residues that can harbor microbial populations.

The minimal temperature-time combination to sanitize equipment using hot water is 180°F (82°C) for at least 20 minutes.  This temperature must be obtained at the coldest point in the bottling line.  For bottling operations, this will be where water leaves the system.  Butzke (2010) notes: “…that humans perceive water as painfully hot at temperatures just above 42°C (108°F).”  Therefore, temperature readings should be taken with a calibrated, food-grade thermometer.

Individuals should take caution when working with scalding material or any chemical agent during the sanitation step.  Always remember to ensure that employees have proper safety equipment and adequate ventilation.

Note that if you are using hot water, heat, or steam to sanitize the bottling line, you will need to bring the equipment back to the temperature of the wine to avoid cooking the first few gallons of wine that flow through the bottling line.  Do not use tap water to change the temperature, as this will ruin the purpose of the sanitation step.  Some wineries prefer to lose the first few gallons of wine, while others will follow a heat step with cold acidulated-sulfur dioxide mix.

Fill heads are an easy source of potential contamination.  Periodically throughout bottling (i.e., every hour, or every time that breaks are taken), these can be sprayed or misted with 70% food-grade ethanol to ensure proper sanitation.  Allow the ethanol to evaporate before proceeding.  Wineries could also dip the ends in a properly made acidulated-sulfur dioxide mix.  Do not wash off sanitized equipment with a towel or “clean” paper towel.

Always remember that the efficacy of cleaning and sanitation is dependent on the processor to complete this task correctly.  Both cleaning and sanitation should take place immediately before bottling and immediately after bottling is completed.  For more information on proper sanitation techniques, wineries can attend the Penn State Food Safety and Sanitation Short Course, which emphasizes key concepts related to sanitation processes.  This course is also available in online content.

Additionally, the book, Winemaking Problems Solved, has an entire chapter designated to trouble shooting during bottling operations, and is recommended for any winery.

  • Checking sterile filtration integrity

Filter integrity is an easy step that wineries can take to ensure their sterile filtration unit is working properly.  Remember that sterile filtration requires the use of a 0.45 micron (or smaller) absolute filter cartridge.  The Bubble Point Test is an integrity test that should be applied to a filter before and after bottling to ensure filter integrity.

  • Bottle washing

While bottles are sterile when they are formed, many retain cardboard dust (“case dust”) in the bottles by the time they reach the bottling line in the winery, and this acts as a contamination point.  Wineries should also be aware of tiny glass shards that may be retained within the bottle during glass manufacturing.

The best way to remove dust and debris in the bottle is by gas jetting: injecting a small stream of inert gas (e.g. nitrogen) prior to the bottle’s use.

As this is not a sanitation step, it is recommended that bottles also undergo a pre-rinse step with an approved no-rinse sanitizer.  Many wineries utilize an acidulated-sulfur dioxide rinse or ozonated water.

  • Inspecting filled bottles

Many wine microbiology text books recommend sampling one or two filled wine bottles every hour during bottling.  There are several things that wineries can look for including using a microscope to scan for potential contamination, using membrane filtration to enumerate yeast and bacteria on a Petri Dish (pg. 236-238 in Wine Microbiology), or sending samples away to test for bottle sterility.  This quality control step can help minimize worry post-bottling and provide ample feedback regarding bottle efficacy.

Petrifilm that show yeast and mold populations from wine sample.

Petrifilm that show yeast and mold populations from wine sample.

  • Checking sulfur dioxide depletion

The use of sulfur dioxide is the last line of defense in terms of microbial stabilization while wine is in bottle.  Many refermentation incidents are a result of too little free sulfur dioxide in the bottle.

Aeration-Oxidation (AO) system set up to measure free sulfur dioxide.

Aeration-Oxidation (AO) system set up to measure free sulfur dioxide.

During bottling, the wine will lose a little bit of the free sulfur dioxide concentration.  Typically, this is around 10 ppm of free sulfur dioxide concentration, but it will vary from winery to winery, and bottling line to bottling line.  Wineries should sample the sulfur dioxide concentration about 24 hours post bottling to evaluate the average loss of sulfur dioxide during the bottling process.  Extra additions of sulfur dioxide can be made before bottling to compensate for the loss during the bottling process.

Resources & Literature Cited

The Brewers Handbook

Butzke, C. “How long do I need to disinfect my bottling line if my hot water is less than 82°C (180°F)?” in Winemaking Problems Solved

Microbiological Analysis of Grapes and Wine: Techniques and Concepts

Neradt, F. 1982. Sources of reinfections during cold-sterile bottling of wine. Am. J. Enol. Vitic. 33(3):140-144.

Renouf, V., M.-C. Perello, G. de Revel, and A. Lonvaud-Funel. 2007. Survival of wine microorganisms in the bottle during storage. Am. J. Enol. Vitic. 58(3):379-386.

Wine Microbiology

Winemaking Problems Solved