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Comparison - 'top' and 'bottom' fermenting yeast

Started by Parky, November 18, 2014, 10:02:50 AM

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Parky

Thought I'd throw up a quick pic for anyone who's interested in seeing 'top' and 'bottom' fermenting yeast at work.

Although the yeast in each FV is distributed throughout the wort, the ale yeast on the left (Safale S05) has created a thick foamy head on top. The lager yeast (WLP810) on the right has a clean white head on top with no foam layer.

Both yeast types were pitched at the same temp (16 deg C), into the same batch of wort (for a Californian Common), and have been fermenting side by side for 36 hours at 15 - 16 deg C. The only variable that's different here (within reason) is the yeast type, as I wanted to see how they compared (based on this article here - http://homebrewbeer.biz/2012/05/sf-lager-vs-safale-05-in-a-california-common/ ). Will certainly be interesting to see how this one turns out.

(Sorry for the crappy pic - taken far too early this morning  ;))


Qs

Cool experiment, I look forward to hearing how they go.

HomeBrewWest

Hmmm, but should the fermentation temperatures not be different (range 59-75F for S05 and 50 to 65F for WLP810)? If you ferment outside the optimum temp range for a yeast, won't you get some off flavors and aromas?

Its a very interesting topic though. Yeasts need constant temperatures too so fermenting with a lager yeast in the shed isn't necessarily a good idea either unless the temp is somehow kept constant.

We have a big decision to make re a new kit . . . . west coast yeast or true lager yeast? The west coast yeast is a Mangrove Jacks US West Coast top-fermenting ale yeast, but one which gives very neutral flavor characteristics to the beer (i.e. without the fruity ale esters and other congeners) so that a lager recipe brewed with this strain should still taste like a lager.  The lager yeast would probably be better if fermented between 10 and 15 oC.

Regardless, its important to maintain a CONSTANT fermentation temperature. If you don't have temp control equipment, I think its probably easier to do this indoors (i.e. about 19 oC for the west coast).

I think it comes down to whether you can keep the lager yeast at a constant low temp. If you cant then you may lose most of the benefits (regardless of whether its a dry or a liquid strain)?
"I am a firm believer in the people. If given the truth, they can be depended upon to meet any national crisis. The great point is to bring them the real facts, and beer." Abraham Lincoln. www.homebrewwest.ie

Garry

Quote from: HomeBrewWest on November 18, 2014, 11:18:02 AM
Hmmm, but should the fermentation temperatures not be different (range 59-75F for S05 and 50 to 65F for WLP810)?

Quote from: BeerSmith
California Common Beer
Amber Hybrid Beer

Fermented with a lager yeast, but one that was selected to thrive at the cool end of normal ale fermentation temperatures.

Interesting experiment Parky. I'm surprised how well the S05 appears to be doing at such a low temperature.

Parky

Quotebut should the fermentation temperatures not be different?

Great point, normally ale and lager yeasts ferment at different ends of the temperature scale and never the twain shall meet. The WLP810 is different in this regard, as it's a lager yeast that ferments at temperatures usually only suited to ale yeasts.

The ideal temp ranges for both are as follows - WLP810 (14 - 18 deg C) and Safale S05 (15 - 22 deg C). So for these two yeasts there's a cross over point where they'll both do well, and I chose 16 deg C as being that happy place for each  :)

The WLP810 can be used in other styles, but is particularly associated with the Californian Common. The Safale S05 seems to fit the requirements of this style well as it makes for a good clean ferment with low diacatyl at the lower end of it's ideal temp, so I would expect a similar profile in the finished beer - although who knows what will happen in practice, that's half the fun of brewing  ;)

The real question I guess I'm trying to answer here is whether the beer made using Safale S05 will give that same clean lager taste as the WLP810 (see article link in OP above). (Safale S05 is less expensive, and as it's a dried yeast is a little less fuss).

QuoteI think it comes down to whether you can keep the lager yeast at a constant low temp. If you cant then you may lose most of the benefits (dry or liquid).

For myself (and I presume a lot of other homebrewers), making a true lager isn't really practical, as I don't have the set up to maintain that all important constantly low temp, as you say, whether for fermentation or lagering later. So for me the Californian Common is a good compromise between an ale and a lager, and easy to brew at home.

QuoteWe have a big decision to make re a new kit . . . . west coast yeast or true lager yeast?

That's a good question, I haven't used that Mangrove Jack yeast yet, but you won't know until you give it a go - sometimes what looks good on paper may need a little tweaking in practice. Would be interesting to find out though.

Parky

[UPDATE - from 22/11/2014]

It's been a busy month, so slight delay in getting these pics up. Both beers are currently conditioning in bottles, and I'll be posting tasting notes for each in a week or two, for anyone who's interested.

All photos below were taken on 22 November (6 days after pitching). The primary phase of fermentation had completed in both FVs by that stage, and the krausen had fallen back into the wort.

-----------------------------------------



Figure 1: Top of demijohns - After Day 4 the heavy foam on top of the wort with S-05 began to break up and sink to the bottom in clumps. The yeast in the WLP-810 demijohn began flocculating also, but in a less spectacular fashion. Although not entirely clear from the photo above, the wort in the S-05 demijohn was relatively clear on Day 6, whereas the WLP-810 wort was still quite cloudy.




Figure 2: Side by side comparison - The clarity of the S-05 wort is more apparent in the pic above, although the biggest difference to be noted is the level of wort in both FVs and the amount of yeast in the WLP-810 blow-off container. There was equally vigorous fermentation in both FVs, but the lighter foam in the WLP-810 demijohn seemed to travel through the blow-off tube more readily, resulting in a loss of wort and quite a bit of yeast.

In this trial there's no way of knowing if the loss of yeast affected the fermentation negatively, but if I was fermenting with this setup again I would use a sealed and sanitised blow-off container (with airlock), and collect the yeast beneath pre-boiled water. It seemed like a shame to waste all that good yeast  :(

The thick foam layer on top of the S-05 FV appeared to prevent the same losses of wort and krausen, although when the foam fell to the bottom it did create a thicker layer of crud than in the WLP-810 FV. In real terms this meant that, despite losing some wort to blow-off in the WLP-810 FV, I actually got about the same volume of beer at bottling time from both FVs.




Figure 3: Bottom of demijohns - The amount of yeast lost through the blow-off tube of the WLP-810 FV is really clear in the photo above, with just a slight coating of yeast in the bottom of the S-05 blow-off container. The colour of the water in the WLP-810 container also tells a story about how much wort was lost through the blow-off tube.

Another interesting observation is the very clear white layer in the trub at the bottom of the WLP-810 FV. The same thin layer can even be seen in the trub at the bottom of the WLP-810 blow-off container. No such layer was seen in the S-05 FV

Would be interested to know if this is yeast or something else, as I haven't seen such a well defined layer before?

beerfly

Really cool experiment.  No idea about the White layer, can see a bit of it in the s05  but it is very light

winstonia

I always get that white layer when I wash my yeast so assumed it was yeast.

Parky

QuoteI always get that white layer when I wash my yeast so assumed it was yeast.

You're probably right, I've never seen a yeast layer as white as that, or as well defined, so was just curious. I'll be taste testing at the weekend, so looking forward to seeing how it's actually turned out ;D

Parky

[UPDATE - from 10/01/2015]

At long last tasting day arrived, and I was eager to see how this one would turn out. I recruited three pals to assist me with a blind taste testing, as I was looking for some feedback on the difference between California Common beers fermented the yeast varieties - Safale US-05 and Whitelabs San Francisco Lager Yeast (WLP810).

With the help of Mrs Parky, each of us was presented with a tasting glass marked either 'A' or 'B', with no indication of which one contained beer fermented with US-05 or WLP810. I had a scorecard prepared, marking the different qualities of each beer out of five (e.g.: appearance, mouthfeel, taste, etc.), but this didn't work well in practice, so we decided to record our collective impressions of each beer instead -



APPEARANCE -

Both beers are very clear and have a similar colouring, a darkish amber brown, with good carbonation in each. The head on the WLP810 beer is slightly more frothy than the head on the US-05 beer, which is somewhat thinner in the middle, although both do show good lacing on the side of the glass. Good head retention throughout from both beers.

AROMA

Initially a strong aroma of the Northern Brewer hops in both, earthy and slightly sour, although a hint of warm malt in the WLP810 beer.

TASTE

Both beers taste fresh and crisp, with no diacetyl detectable in either. The Northerm Brewer hops seem to dominate the initial taste in both beers, with a nice refreshing finish on each. Subsequent tasting reveals a warm malt profile to the WLP810 beer, whereas the US-05 has a 'cleaner' malt taste. The finish on both beers is refreshing, although a slightly crisper and sour finish to the WLP810 beer. The beer brewed with US-05 has a nice clean finish, but lacks the sourness and refreshing 'bite' of the WLP810.

PALATE

Both beers have medium carbonation, showing small bubbles, and tasting refreshingly and light. Both beers have a slight bitterness detectable on the finish, although the WLP810 is slightly drier at the end.

OVERALL VERDICT

Although this taste test was subjective, and none of the participants were BJCP judges, the consensus was that both yeasts produced two very good beers. Both fermented clean, showcased the Northern Brewer hops, and had that refreshing finish characteristic of the California Common style. Digging a little deeper, the beer fermented with WLP810 showed a little more complexity than the US-05, with a warmer malt profile, and a more crisp and slightly sour finish.

CONCLUSION

The question I attempted to answer in carrying out this trial was whether a beer fermented with the dried yeast Safale US-05 would be comparable to White Labs liquid yeast WLP810 San Francisco Lager yeast (which is the strain of yeast associated with the California Common style of beer).

From a practical perspective US-05 is a readily available, relatively inexpensive yeast, that only requires rehydrating before pitching. The WLP810 on the other hand is best kept chilled, is expensive, and requires the additional step of making a starter before pithing into the wort. Both yeasts claim to have low diacetyl and a clean taste, and both certainly delivered in this regard in the present comparison test.

If I was brewing a California Common as a refreshing session beer the Safale US-05 would make a very good beer in that style. But if I were looking for a beer to sip over and appreciate the subtle nuances of a California Common, then White Labs WLP810 would be have to be the yeast of choice.

RECIPE

I'm posting the California Common recipe used in the trial below for anyone who's interested in making this clean and refreshing amber hybrid beer -

California Common Beer

Recipe Specs
----------------
Batch Size (L):           10.0
Total Grain (kg):         2.114
Total Hops (g):           39.68
Original Gravity (OG):    1.049  (°P): 12.1
Final Gravity (FG):       1.010  (°P): 2.6
Alcohol by Volume (ABV):  5.07 %
Colour (SRM):             8.7   (EBC): 17.2
Bitterness (IBU):         15.7   (Average)
Brewhouse Efficiency (%): 70
Boil Time (Minutes):      60

Grain Bill
----------------
1.522 kg Pale Malt (72%)
0.200 kg Dextrose (9.46%)
0.196 kg Biscuit (9.27%)
0.196 kg Crystal 40 (9.27%)

Hop Bill
----------------
9.0 g Northern Brewer Pellet (6.1% Alpha) @ 60 Minutes (Boil) (0.9 g/L)
12.3 g Northern Brewer Pellet (6.1% Alpha) @ 15 Minutes (Aroma) (1.2 g/L)
18.4 g Northern Brewer Pellet (6.1% Alpha) @ 0 Minutes (Aroma) (1.8 g/L)

Misc Bill
----------------

Single step Infusion at 66°C for 60 Minutes
Steeped grains (Crystal 40) in 1.5L water at 70°C for 30 minutes
Fermented at 16°C with Safale US-05/WLP810 for 21 days
Bottle conditioned at 23°C for 10 days
Cold conditioned at 10°C - 12°C for 4 weeks

Additional notes
----------------

Liquid yeast pitched directly into wort (no starter required for 5 litre batch)
Dried yeast (6grms) rehydrated in 200mls pre-boiled (and cooled) water at 38°C for 30 mins
Primed with sucrose for carbonation level of 3 volumes.