Yeast Slant FAQ by Mike Sims

Yeast Culturing FAQ

Mike Sims

msims73 at mchsi com

Equipment materials needed

1) Agar Agar

2) Test tubes

3) Pressure cooker

4) Inoculation loop(s)-disposable or metal loop and flame source

5) Turkey baster or large syringe

Agar Agar-

Looks like cellophane

Available at Asian grocery stores, one $3-4 package will last forever if kept dry. Another option is to buy the powdered “pharmaceutical grade” agar from a homebrew retailer. Waste of money IMO.

Test tubes-

I bought mine off ebay 100 for $25 including shipping. That’s $.25 a tube and they’re reusable. You may have to keep checking ebay, but they are for sale there often. My slants are Pyrex screw cap tubes model 9826-20x (phenolic caps are the best for repeat use). These tubes make larger slants than those sold at homebrew shops. With these, I like to think that I get a colony of yeast close to the size of a smack pack. With my stir plate I can have a 500ml starter ready in 24hrs or less and without the stir plate it takes about 3 days. Considering a smack pack plus starter step up can take 3 days or longer, I’m pretty happy with that.

Slant prep

-Make a standard starter 1040 wort. About a quart size solution will do. If you use the slants I use, this will make about 20+ slants, more if you use smaller ones. Bring to a boil and slowly add agar. Too much at time and it will clump up. Add more as it dissolves, stirring often. You’ll want to add enough so that when it sets; it’s not too soft or to firm. This is something you’ll have experiment with.

Once you have your agar ready, you can take it off the heat. While it’ still warm it will be liquid for a good 15 min’s and will give you plenty of time to fill your test tubes.

Using a turkey baster or large syringe

fill slants about 1/3-1/2 full. You don’t want to over fill the test tube,

Agar still in liquid form

Overfilling can form a plug of agar that CO2 from the yeast can get under and push the agar up (and maybe out) the slant when you open it.

Once you have your tubes filled, place caps on and leave slightly unscrewed, this will allow air to escape when pressure cooking. Place tubes upright in autoclavable test tube rack or mason jars or other heat safe glass. Place in pressure cooker with about 2 inches of water.

Follow your pressure cooker’s instructions for safety. Pressure cook at 15 psi for 30 min’s.

15psi=250deg’s=no bacteria spores or mold

Let your pressure cooker cool down enough to open, and using oven mitts, remove test tubes one at a time screwing each lid tight. Lay tubes on a slight slant just so that the agar comes up to the base of the cap. Let cool until firm and you now have your slants.

Notice the smaller tube; this came from morebeer.com, not even 1/3 the surface area!

Inoculating the slants

Materials –

1) Slant

2) Loop(s)

Disposable loop Nichrome metal loop Denatured alcohol lamp

3) Gloves

4) Small bowl of sanitizer

5) Spray bottle of sanitizer

6) Dust respirator (or hold your breath while inoculating)

7) Smack pack or pitchable tube of yeast

When culturing slants, I make roughly 3 slants of each strain at a time. I make an attempt to re-culture onto new slants every 6-8 months.

Get everything together on a clean surface. Sanitize gloves, outside of slants, smack pack or tube with spray sanitizer. Open up your yeast, place slant in one hand (with practice you can hold and inoculate all three slants to save time) and loop in the other, open slant placing cap in sanitizer bowl, flame loop or using disposable loop, dip loop into yeast sample. Insert loop into test tube, being careful not to touch glass sides or media and go all the way to the bottom of the slant. Drag loop back up the surface of the media in zigzag motion. Repeat until you have good coverage, about or three times, and repeat for each slant. Avoiding touching the glass inside the test tube will ensure no deposits of yeast on the glass of the test tube witch can dry out and possibly become bacteria food (rare if you’re sanitary).

Put cap back on and leave slightly undone and place or lay in a bowl and cover slant with a kitchen towel. Leave slant at room temp for 3-5 days depending on yeast strain. When you have a good crop of yeast on the slant, screw cap on tight and place in the refrigerator, preferably as close to 33 degrees as possible.

Healthy yeast culture, notice side to side coverage.

Pitching yeast into starter

Take a vial of yeast out of the refrigerator and let warm up to room temperature. Make your regular starter solution. When starter is cooled and ready, open (sanitized) slant tube and use a sterile eye dropper to place wort into test tube (or just decant directly from the starter). Replace cap and shake vigorously dislodging the yeast into suspension. Occasionally you may need to use your inoculating loop to scrap the surface of the slant to get all the yeast loose. Next, just pitch the yeast into the starter and let the yeast do their thing.

Disclaimer: I take no responsibility for any inaccurate or potentially dangerous actions or reactions of anyone following these instructions. Especially you drunk asses playing with a pressure cooker J