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Making Lacto starters (OYL-605) from frozen stocks

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isomerization

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Just recently got into brewing kettle soured beers, using OYL-605, can't recommend that strain(s) enough!

Anyways, I normally store glycerol stocks of my yeast cultures in the freezer (-80C, but -20C is doable as well with the right setup). I hadn't seen much information RE making lacto freezer stocks and how well they might perform. Considering OYL-605 runs around $10 a pitch, well that's a bit too steep when the grain bill for a gose is less than that!

My original Lacto starter was 500 ml of 1.040 DME wort (pinch of yeast nutrient too). The entire OYL-605 pouch went in there and the pH was monitored over ~40 hrs (24 hr = 4.00, 40 hr = 3.60) at RT. I saved glycerol stocks of the final starter and used this starter in a Margarita Gose (thanks Morrey!) kettle sour. This starter got the raw wort down to pH = 3.20 in just under two days at RT.

Fast forward a month, and I tested the glycerol stocks, using the same setup as above. I tested two pitch volumes (~1 ml and ~10 ml) into 500 ml wort.

After 20 hrs, the 1 ml stock was at 3.61 and the 10 ml was at 3.54. After 44 hrs, the 1 ml stock was at 3.47 and the 10 ml was at 3.39.

I don't plan on using these starters for anything in the short term, so I can't evaluate their performance in a kettle sour, but I think the pH drop indicates they are healthy and happy! I will likely make another gose this summer, so that will be the "real" test as to how these freezer stocks perform (also will see if there is a "best by" time limit for being in the freezer too).

Just wanted to share, in case anyway wanted to do something similar.
 

TravelingLight

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Thanks for the info. I've got a 50 ml tube of 605 I harvested off my starter the last time I did a Morrey gose. I planned on using it within the next two months but I was cautiously wary since I've never saved a pure lacto pitch like this. Even though mine are only in the fridge as opposed to your freezer stocks, you've given me some confidence.
 
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isomerization

isomerization

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Thanks for the info. I've got a 50 ml tube of 605 I harvested off my starter the last time I did a Morrey gose. I planned on using it within the next two months but I was cautiously wary since I've never saved a pure lacto pitch like this. Even though mine are only in the fridge as opposed to your freezer stocks, you've given me some confidence.
Just make sure you follow the pH of your starter, I think that is honestly the best indicator of Lacto growth/health (for us homebrewers that don't have a centrifuge). Even pH strips should give you something, as a DME starter is around pH 6 to start with.
 

TravelingLight

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Just make sure you follow the pH of your starter, I think that is honestly the best indicator of Lacto growth/health (for us homebrewers that don't have a centrifuge). Even pH strips should give you something, as a DME starter is around pH 6 to start with.
Good call. I've got a digital pen I use to monitor my kettle sours. Need to upgrade, but it works ok for now.
 
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