This is an issue of encountering Diacetyl when using Go Ferm from Lallemand.
Lallemand’s collaboration with the INRA in Montpellier and other institutes throughout the world confirmed the critical role of yeast micronutrients, but more importantly, it identified the most effective way to ensure that these micronutrients benefit the selected yeast.
The result of this research was the development of GO-FERM®, a natural yeast nutrient to avoid sluggish and stuck fermentations. GO-FERM® is specific inactive yeast produced through a unique yeast biomass process fine-tuned to obtain high levels of certain essential vitamins, minerals and amino acids required for healthy yeast fermentations.
The GO-FERM® approach is to provide bioavailable micronutrients in the non-stressful environment of the yeast rehydration water instead of the traditional method of adding micronutrients to the must. During rehydration, the yeast acts like a sponge, soaking up GO-FERM®’s bioavailable nutrients. This direct contact between GO-FERM® and the yeast in the absence of the must matrix avoids chelation of key minerals by inorganic anions, organic acids, polyphenols and polysaccharides present in the must. It also prevents essential vitamins from being rapidly taken up by the competitive wild microflora or inactivated by SO2. By making key minerals and vitamins available to the selected yeast at the critical beginning of its stressful task, the yeast’s viability increases and fermentations finish stronger.
The use of GO-FERM® results in significantly better overall health of yeast cells through-out the fermentation, affecting fermentation kinetics and resulting in a cleaner aromatic profile.
So I use dried yeast almost every time I brew. I really like the products from Fermentis, Safale S05 in particular.
I purchased the book "Yeast" by Chris White and I forget the other contributor, but anyway in the book he mentions trying a product called Go Ferm from Lallemand. This is a yeast nutrient designed to be added to the rehydration water for dried yeast. I always rehydrate my yeast. This product is supposed to supply critical nutrients to the yeast during the rehydration phase and improve fermentation, attenuation, and beer flavor.
My first use of this product was with a Lager and it ended up with MAJOR diacetyl. Primary ferment was 10 days at 52 and I raised it to 56 on day 11, 58 on day 12. Fermentation really took off and then the beer cleared within about a week of that. I made the mistake of not taking a gravity reading or tasting it until I racked it at 18 days to keg. After a few days at 6 psi I took a taste test and was overwhelmed with slick butter. I let it age for 6 weeks at low pressure, occasionally venting it and letting it sit for days then, tasting it regularly and it improved gradually but was eventually dumped after 6 weeks.
Shortly thereafter I used it with S05 but I used less this time. Rather than adding a tablespoon, I added a half teaspoon.
Result was a slow take-off ( slower than I'm used to seeing ) sluggish ferment at 65 degrees but eventually it completed at 14 days primary. I racked to keg and again noticed diacetyl. Not nearly as strong but it's there. I can drink the beer, but it's quite noticeable. I've NEVER had diacetyl with S05 and I've brewed dozens of batches with it.
Next batch was again with S05 but I didn't add any Go-Ferm to the rehydration water. No diacetyl in the beer. It tastes great and is on tap now.
Last weekend I brewed a Lager once again using Saflager W34/70 and this time I skipped the Go Ferm. I am really looking forward to the results but don't have anything to report yet. I can say at day three it's much more active than the previous batch which used the Go-Ferm in rehydration water but without any gravity readings to compare, I can only provide subjective data.
So does anyone else here have experience with this product and beer yeasts? I understand this is generally used for Meads and Wines, not beer yeast. I emailed Fermentis to ask about any nutrient they may already be adding to their dried yeast and what their thoughts are on Go Ferm, but I've not received a reply.
I might just start adding this to the boil instead and use it up as a kettle nutrient. It's that, or compost it I guess.