Just a question. Looking at the chart, the performance of the ferment during the primary appears almost identical between DAP and Fermaid-O, with the only obvious difference being that 46 hour tail end. Why is that significant? I know the yeast do a lot of "clean up" late in the ferment, but do we know whether this activity happens in the primary earlier for the method that ends 46 hours earlier? (Can't tell which method is which in the chart; I think a header or footer got cut off.)
I would love to see this test repeated in a mead must rather than grape must. It'd be a much truer test, since honey must is almost a blank slate when it comes to nutrients. How are they measuring fermentation activity? Rate of carbon dioxide production? Thermal imaging? Continuous gravity/brix readings?
If you look closely you will see that the line which indicates organic nitrogen doesn't exist in the chart after about 160 hours. This is because fermentation has finished (no line to plot) for Fermaid O 46hrs earlier despite only 1/4 of Nitrogen supplied (5mg vs 20mg). The significance of finishing earlier is that, as Medsen already said, you can finish fermentation even without supplying any nutrients at all. But that ferment may take up weeks and months. During this longer time the yeast are starving for nitrogen and are stressed. It's not the shape of the graph which is significant for this thread (although the dap ferment shows higher spikes, and the dap ferment initially goes faster but soon peters out), but where the lines end on the graph.
From the pdf I linked "Yeast Nutrition and Protection for Reliable Alcoholic Fermentation - The State of the Art", it seems they might be measuring Co2 released (pg 18 and 19). Of course there is no way of verifying what they used for that particular chart, even if it is featured in the same pdf but on different pages.
Yet another theory why we can get away with lower Fermaid O additions
- Fermentations with Fermaid O (especially using Tosna) vs Fermaid K take longer. This corresponds to Medsen's link to Pollen use (pg 5). Fermaid O and Pollen are different, yet both are organic so bear with me
- Fermentations using over 140ppm for pollen provided the most sensory impact, yet all additions finished fermentation
- On pg 7, we see that up until P40, honey characteristic was increasing reasonably, yet then from P40 to P50 it shot up from around 20 to around 80, which is just amazing. Meanwhile, the fruity characteristic are best with the smaller addition P20, and the largest addition P50. Everything in between is less. The point is:
It seems sensory contributions do not improve linearly vs yan
- Mazers have decided to up the amount of yan supplied to musts based on sensory contributions. It was found during Medsen's 'pendulum swing' he mentioned that mazers upped the amount because they found it better and better (particularly with respect to sensory contributions)
Therefore, it is possible that like P10 to P40, Fermaid O manages to finish the mead anyway with less organic yan. However, unlike pollen, Fermaid O might behave similar to P20's fruity aromatic and produce surprisingly better aromatics at lower nitrogen levels. OR, perhaps it would be shown that sensory contributions are not very much affected by yan supplied to must. The reason for this would be that Fermaid O might contain certain amino acids and amounts which are different (and better) than pollen. Looking at the list of amino acids found in pollen there are quite a few!
TLDR, maybe the pendulum could swing back (and further back than before) if sensory contributions are unaffected, or improved, by lower doses of Fermaid O and if we are ready to wait a couple of days extra for fermentation to finish. I, for one, would certainly not mind waiting an extra couple of days for fermentation to finish if it meant my mead will taste better. Unfortunately, I don't think there is an article which can shed light on this theory
just googled and we see its in the last one too.
