Solid to Liquid Transfer

The purpose of this procedure is to transfer one or more yeast colonies grown on a solid media to a test tube containing a liquid media, maintaining sterile conditions.
The liquid media could be sterile distilled water for long term storage, or sterile wort for fermentation and propagation.

The usual precautions apply: scrub the table surface, the test tube and your hands with alcohol. Wear a mask, keep your work area as dust-free as you can, work in flame zone.
Since you need to work as quickly as possible, you should practice with empty test tubes ahead of time, to gain the necessary dexterity.

Examine the colonies on the plate and select a few round, healthy, well isolated ones. You can mark them with a felt tip pen on the bottom of the dish.
Place on the table the Petri dish upside down (media on top, cover on bottom), test tube with liquid media (standing in its rack), inoculation loop.

When ready, proceed as follows:

  • Hold inoculation loop with right hand
  • Flame loop from tip to handle until it's red hot, then keep it in the flame zone

Content on this page requires a newer version of Adobe Flash Player.

Get Adobe Flash player

  • With your left hand, lift the media half of the Petri dish and hold it vertical ( to minimize the chance of dust falling on the agar), leaving the cover on the table
  • Touch the media surface with the loop, to cool it
  • With the loop, scrap one or more of the selected colonies
  • Place the loop near the flame (not too near, of course...) and put plate back on its cover
  • Take test tube with left hand
  • Grab tube cap with right hand little finger, unscrew by turning tube with left hand. Hold cap between the little finger and the palm of your right hand

Content on this page requires a newer version of Adobe Flash Player.

Get Adobe Flash player

  • Flame tube mouth
  • Working in the flame zone, dip loop in the liquid without touching the glass walls, swirl it until yeast comes off the loop.
  • Remove loop and put away
  • Flame the tube mouth again and place cap back on, again using left hand to screw it

Content on this page requires a newer version of Adobe Flash Player.

Get Adobe Flash player

The plate is about useless now, and you can discard it.

If you are preparing a master for storage, you can wrap the tube in aluminum foil, label it and store in the refrigerator.

If you inoculated a tube of sterile wort, you should incubate it in a warm (>27 °C) dry clean place. Expect signs of fermentation within 12 hours. Crack the cap open to release CO2, then proceed with starter propagation or plate again for further selection.

horizontal rule

Liquid to Liquid Transfer

Use this procedure to step up a starter.
That is, to transfer fermenting wort from one flask to a larger one containing more sterile wort.

The usual precautions apply: scrub the table surface, the flasks and your hands with alcohol. Wear a mask, keep your work area as dust-free as you can, work in flame zone.

Proceed as follows:

  • Take smaller flask with left hand, swirl to bring yeast in suspension
  • Grab flask cap with right hand little finger, remove and discard it
  • Hold the larger flask with your right hand
  • With left hand, remove cap from larger flask, hold cap between the little finger and the palm of your left hand. Pay attention not to spill the contents of the smaller flask
  • Flame mouth of both flasks
  • Working in the flame zone, pour the suspension from the smaller into the larger flask. The two containers should never touch
  • Flame again the mouth of the larger flask, then place cap back on

horizontal rule

Wort to Flask Transfer

Use this procedure to prepare a sterile flask with canned sterile wort for use as a starter.
That is, pour the content of a previously canned wort jar into a sterile flask.

The usual precautions apply: scrub the table surface, flask, jar and your hands with alcohol. Wear a mask, keep your work area as dust-free as you can, work in flame zone.
Place on the table a sealed jar of sterile canned wort and a sterile flask of the appropriate size.

When ready, proceed as follows:

  • Open the wort jar but do not remove cap
  • Hold empty flask in left hand
  • Remove flask cap with right hand little finger, hold cap between the little finger and the palm of your right hand
  • With right hand, remove cap from the wort jar
  • Flame the mouth of both the jar and flask. A portable propane torch is best suited for this task
  • Carefully pour the wort from the jar into the flask. The two containers should never touch
  • Put away the jar
  • Flame the mouth of the flask, put cap back in place (or fit airlock)

When the flask is a large one, say 1000 ml, a considerable amount of CO2 is produced during fermentation, so you might want to use an airlock.
The flask would probably have been autoclaved capped with aluminum foil, and the airlock and rubber bung would have been soaked in a disinfectant solution.