Steaming the Bottling Line

By: Thomas J. Payette, Winemaking Consultant

Steam is one of the most widely used methods of sanitizing a bottling line and cartridge filter prior to bottling.  If done properly a “sterile bottling” can be secured at each bottling run.  Steam, for safety reasons, is a nuisance, yet most wineries still find it the bottling sanitation measure of choice.  Steam is hazardous to use and the author accepts no liability for error on behalf of the operator.  Please be careful if this is your first time!  Be careful every time!

  Bottling is an important time to be on your game.  You will only get one chance to do this properly so it must be taken very seriously.


  A winemaker interested in bottling a wine sterile will want to eliminate all viable bacteria and yeast from the bottling line and final filter prior to bottling day.  Even winemakers who are bottling unfined and unfiltered wines sterilize their bottling lines before bottling for extra security.  Steam, when used properly, is lethal to all living organisms.


  Live steam is the key to doing this procedure properly.  If an orifice or filler spout is expected to be sterile, a flow of live steam must be coming from that area.  Below are guidelines for steaming a bottling line and final filter prior to bottling.  Some of these principals may need adjusting for your specific line set up.

  Before starting the below procedure, it is recommended to rinse out all the areas that will come into contact with the steam.  Do a visual inspection for dust or foreign matter in areas that will come into contact with the wine – filler bowl, filter housing, filler spouts, etc.

1.    Secure a source of steam that will be abundant enough to handle the set-up.  A six-spout gravity flow filter may require less output from the steamer than a 16 spout filler.

2.    Secure a wine hose that will allow steam to flow through it safely and use it for all the connections down stream of the steam.  This hose should also be appropriate for wine.

3.    Have the steamer as close to the bottle filler as practicably possible while also allowing for a sterile filter cartridge(s) to be placed prior to the filler.  (The closer the items are – the shorter the runs – leading to less error and faster ramp-up in the steaming cycle.)  Some bottling units are nice since a cartridge filter may be attached directly to the bottom of the unit minimizing hose length.

4.    Place a stainless steel T with two valves prior to the cartridge filter and a T with two valves after the cartridge.  Accurate pressure gauges should be placed on the T’s so the winemaker can monitor the pressure during steaming and during bottling.  (Remember to use pressure gauges that are designed to be steamed!)

5.    Attach the hoses as if pumping wine through the filter and to the bottling line.

6.    Open all valves in the beginning.  (If using a mono block – make sure the automated solenoid valve is in the open position to allow steam into the filler bowl.) {If a safety blow off valve is not on your steamer – please install one yourself or take it to a qualified mechanic to install one.}

7.    Turn on the steamer to initiate the creation of steam leaving all the valves down stream of the steamer open.

8.    During the ramping up of the steam, condensed water may flow out of these open valves.  Allow this to happen until it turns to steam.  Then turn the valve toward the closed position but do not fully close.  Leave the valve(s) “cracked” open to allow a small amount of live steam to flow from the valve.  This insures that the valve(s) has come up to the steam temperature and that it will remain at that temperature as long as live steam is flowing from it.

9.    “Chase” the steam through the complete setup and throttling back valves as steam appears.

10. When a full set of steam has reached the final destination of the end of the run (This may be the ends of every filler spout or the leveling mechanism in some mono blocks, etc.)  – we can start timing the steaming operation. Double check that all the filler spouts are open and that steam is flowing.

11. Places to look in the filler bowl may be a drain valve.  Make sure that it is cracked open slightly to allow for a free flow of steam.  Plus the tops of each filter housing etc.

12. Step back and look at the operation asking yourself “Is steam getting everywhere and on all the surfaces that may come into contact with the wine?”  If the answer is – “YES” proceed to timing the operation.

13. Most winemakers steam for a minimum of 18 minutes and up to 25 or more should do little or no harm.

14. During the steaming operation – one may take steaming temperature crayons around to double-check they have achieved the desired temperature at a specific location on the bottling line. Steaming crayons are pencil like devices made of materials that melt at certain temperatures. 

         Caution is important when using these crayons on parts that may contact the wine.  If wishing to test an area coming into contact with the wine – run a trial steaming operation – use the crayons – allow the line to cool and then thoroughly clean the area the crayons have contacted.

15. During the steaming operation – continue to check on the operation to make sure the function is continuing as planned and for safety reasons. Check that filler spouts have not “jiggled” into the closed position.

16. After the steaming operation time limit has been met, the operator may once again check to make sure all the orifices are steaming as needed.  Then turn off the steam source and allow for cooling of the lines, spouts and cartridge(s), etc.

17. Allow the system to come to room temperature and perform an integrity check (procedure to be covered in a future article) on the final absolute membrane filter to insure the unit will perform properly at the rated micron level.  Make sure the parts used to do this are free from microbes and that they have been cleaned with a 70% ethanol solution or equivalent protocol.

18. Do not disconnect any of the lines at this juncture.  Use a spray bottle of the ethanol referenced above on all areas that have a possibility of compromised sterility.  When in doubt – spray it!  Filler spouts – too! The winemaker has a totally sterile system from the final filter down stream to the filler spouts!

19. Aseptically close the filler spouts so they will retain wine when wine flows to them.

20. Attach the upstream line that was connected to the steamer to a source of appropriately pre-filtered wine.

21. Start the flow of wine slowly through the system once again “chasing” the wine through the cracked valves.  Some water may be allowed to drain off before wine reaches its destination.

22. Once the wine is completely through the system – complete the cycle by running several sets of bottles through the filler and returning that wine to the wine tank being bottled.  This will insure the first bottle of wine off the line will be exactly the same composition, as practically possible,  as the last bottle of wine.

23. Resume the normal bottling operation.

24. After bottling rinse the final filter with water and perform another integrity check to confirm the filter held all day.

25. Once bottling is complete, make sure to rinse all the areas of the transfer lines, final filter housings and filler bowl / spouts to remove any residue of wine.  Some winemakers (like me) will actually rinse and then resteam the line without the final filter while cleaning up at the end of the day.  This is a great idea especially after running a cuvee for sparkling wine on your “everyday” bottling line.  Remember one will still want to steam prior to the next bottling – too!

26. Send a bottle off to a certified lab or test in house under a microscope to make sure the wine is indeed clean and refermentation or a malo-lactic is not a concern.  Taking samples at different times of the days bottling run can be a great idea to help identify any problem areas if they should occur later during the bottling day.   

Some Other Helpful Hints: 

•     Use water that is clean and free of minerals to extend the life of the steamer.  Also, some water issues may clog the filters prematurely or during the steaming cycle.

•     If the bottling line has ball valves on the filler or other areas – make sure these are physically clean and sterilized properly with steam.  This is an area that can create cross-contamination issues with bottling.

•     Contact your final filter supplier to make sure the procedures about to be incorporated are in line with their recommendations and to see if they recommend other helpful advice about their product and the specifications of their product.   

•     Contact your equipment dealer to make sure the equipment will hold up to the procedure and to hear potential areas of concerns.  They may be familiar with other wineries that have done these procedures so they may be able to give helpful tips and suggestions.

  If looking to sterile bottle your wines for the first time – take the above steps and recommendations and implement them to cater to your specific bottling line setup.  Every line is different with a new set of places on which to focus or of which to be aware.  Open the lines of communication with your suppliers, winemaker and bottling crew to make sure the above can be implemented successfully. 

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