I finally got around to propagating NCYC 1108 from slant yesterday. For those who have never heard of the strain, NCYC 1108 is the reference strain for type I mutual aggregation. Mutual aggregation is a phenomenon where two non-flocculent strains co-flocculate when used together. The other mutual aggregation reference strain is NCYC 1109. It is the reference strain for type II mutual aggregation. Type I and type II strains co-flocculate when pitched together. Any non-flocculent strain that co-flocculates with NCYC 1108 is considered to be a type II strain whereas any strain that co-flocculates with NCYC 1109 is considered to be a type I strain. Strains of yeast that do not co-flocculate with NCYC 1008 or NCYC 1109 are considered to be type III strains. Unlike adding a flocculant strain such as Wyeast 1968/WLP002 to a batch to sediment a non-flocculent pitching yeast (see Kara Taylor’s NHC 2014 presentation), both NCYC 1108 and NCYC 1109 are non-flocculent when used individually.
With that said, NCYC 1108 is another strain for which I have almost no brewing data; hence, it is another box of chocolates culture (Forest Gump reference). All I know is that it is a chain former that was sourced from a British Brewery. While not all yeast strains that form a yeast head are chain formers, chain forming yeast strains tend to form a yeast head. Chain formation occurs when daughter cells fail to completely detach from mother cells during budding.
I stepped the culture to 600ml this evening. NCYC 1108 seems to sediment well, but it does not appear to flocculate at all. The sediment is easily disturbed. This fermentation is going to be interesting.
Yes, it is a shaken starter. The interesting thing is that I recently discovered that Steven Deeds (Woodland Brewing Research) arrived at the same conclusion as I have with respect to stir plates. He found that the increase over a non-stirred starter was on the order of 9%, which is insignificant in a process where biomass grows at a rate of 2n, where n equals the number of minutes that have elapsed since the end of the lag phase divided by 90. In effect, there is no appreciable gain in biomass growth over a well-shaken starter, and one does not have worry about sterilizing a stir bar (or at least sanitizing it well) or laying out the cash for a stir plate.
In this context, “non-stirred” means non-continuously stirred. In effect, continuous stirring showed no appreciable increase in biomass growth over a starter that is shaken immediately after inoculation and periodically swirled if necessary.
The National Collection of Yeast Cultures (NCYC) in the UK does a great job of anonymizing their cultures. To further complicate matters, this culture was deposited over fifty years ago when the institution housing the collection was known as the Brewing Industry Research Foundation (BIRF). To the best of my knowledge, NCYC 1108 has been out circulation as a brewing culture for a long time. I can only find references to its use in research papers.
I figured that I would post an update about my experience with NCYC 1108. NCYC 1108 is definitely non-flocculent. The batch has been in a primary fermentation vessel for just under two weeks (Christmas got in the way of brewing), and the yeast cells are only now starting to exhibit signs of sedimenting. NCYC 1108 produced a medium yeast head during active fermentation. I am going to take a gravity reading this evening or tomorrow. It will be interesting see what the beer tastes like because I mashed at 150, and this strain is powdery. I am expecting the beer to be dry, but what I interested in are the yeast produced flavors (or lack thereof).
I finally got around to racking the batch today. The beer was smooth and clean with more malt flavor than BRY 96 (a.k.a. “Chico”). As I had assumed due to its powdery nature, fruitiness was low with no diacetyl. The strain appears to be POF-. Apparent attenuation was 80%. I am pleased with the performance of this yeast strain, but the proof is in how the beer tastes after conditioning.