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.
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.
