Beer Wars

This really answers the question of "Why Budweiser just doesn't get it."  This is a well done documentary following several craft brewers over the course of about a year.  It highlights how "big beer" works hard on pushing out any competition instead of making great beer.

You'll see Sam Calagione founder of Dogfish head and his battles with Big beer. See the saga of Moonshot '69 as it was pushed out of the market.

Overall it was a great movie that made me want to go out and support craft brewing!

PS for those following the Side by Side Starters posts: 
There are several applications of the data from the experiments which I am trying to condense, but this may be a few posts with the final results.  So today is time to take a break from the numbers.

San Diego Super Yeast WLP090

Strain: San Diego Super Yeast WLP090
Testing Date: 2/25/2013
Viability: 40%
Total viable cell density: 50 million cells per ml
Thick Viable Cell Density: 1.2 billion cells per ml
Stress level: Low, Similar characteristic flavors to previous batch.
Bacteria level: Very Low, Sourness unlikely. (no bacteria visible)

Viability – Percentage of live cells of the entire cell population
Total Viable Cell Density – The number of viable cells in one milliliter of homogenized slurry.
Thick Viable Cell Density – The number of viable cells in one milliliter of settled cells such as those at the bottom of a starter that has been refrigerated.
Stress Level – A rudimentary assessment of cell health based on cellular morphology.
Bacteria – The percentage of visible bacteria of the yeast population

Other notes:

This yeast was taken from a starter with a 1.040 (10°P) initial gravity wort made from DME.  The yeast sample is very clean with very little protein trub. Viability was surprisingly low considering this yeast came from a starter. If the cell death was caused by freezing during transportation then the viable cell count could be as high as 125 million per ml (suspended yeast) , and 3 billion cells per ml (settled yeast)

Disclaimer:

This report is an evaluation of the sample that was provided. There are no guarantees. The sample may perform differently than the slurry for a number of reasons that are beyond control. Care is taken to provide accurate results, however measurement error due to equipment tolerances, process, and calibration will create deviation in measurement from absolute values. This is not an evaluation of health or safety risks.

The bright white nucleus seen in the viable cell indicates that there was excellent dye rejection by the yeast cell. Methylene blue works by binding with acids, such as DNA. Even inside the DNA dense nucleus there is no dye. This is a strong health indicator.

Side by Side Starters 3 of 4

Observations of the daily collected data.

When looking at the daily collected data, the first thing that really jumped out was the correlation between sugar consumed and cell count.  Sugar is known to be a limiting factor in cell propagation, but seeing how well the two correlated was surprising.  This opens up a new way to look at yeast growth.  Trying to determine cell growth solely from the input conditions is not using all of the data available.  If in addition the final sugar by weight is used a much better approximation of cell count can be achieved. 

Both of the test vials followed very close to producing 12 billion cells for every gram of extract consumed.  Another way to look at that number is relative to volume.  For each degree Plato the cell density increases by 12 million per ml.

Comparing the two

Both the refrigerated cells and the new cells started consuming sugar almost immediately.  Both had reduced the sugar in the wort by half in the first day.

The daily data shows that the refrigerated slurry out preformed the cells removed from a starter.  This was a second big surprise.  Common brewing knowledge would indicate that cells that have been in the refrigerator for a month will be starved, and will not preform well, however quite the contrary was the case here.

This unusual performance may be linked to glycogen reserves.  At the start of fermentation yeast will build glycogen reserves.  During the growth phase these are significantly depleted during cell division.  At the end of fermentation the yeast will rebuild these reserves as they prepare for dormancy. (1) The cells taken from the refrigerator were allowed to ferment to completion, and even after a month in the refrigerator still had significant glycogen reserves to support cell division.

It seems that it is better to allow a starter to run to completion than to use the cells at high krausen.

(1) Fix, Principles of Brewing Science, p97 in the 2nd addition

Side by Side Starters 2 of 4

The five by eight matrix of tubes was set up to compare the results of varying inoculation rate from 30 million cells per milliliter to 120 million cells per milliliter.  The wort gravity was varied from 3°P to 15°P (1.012 to 1.060) in addition yeast was used from a starter at high krausen for one half and yeast that had be refrigerated for the other half.

To achieve the cell counts each slurry was counted and then varying volumes were added to the culture tubes.  For the active yeast cells these ranged from 2 to 5 ml, and for the inactive culture they ranged from 1 to 4ml.  Adjustments to gravity measurements would be needed because there is inherently residual sugar and alcohol in the slurry.

The array of gravities were achieved by diluting a 31.4°P wort and adding 1 to 5 ml. The remaining volume was filled with water to ensure each tube had 10ml of total volume.

The tubes were allowed to ferment for two weeks and then refrigerated and allowed to settle for several days.  The height of the yeast cake in each tube was measured.  Six cell counts were done and these were correlated to the heights of the remainder of the tubes to produce the final cell counts.  A linear fit based on the number of ml of slurry was used to equate milliliters of slurry to number of cells.  For this fit, the r2 value for the active culture was 0.9936 and the r2 value for the inactive culture was 0.9850

Raw Data

	SO4A-2	SO4A-3	SO4A-4	SO4A-5	SO4I-1	SO4I-2	SO4I-3	SO4I-4
15	15.7	15.7	15.7	15.7	15.7	15.7	15.7	15.7	initial sugar
12	12.56	12.56	12.56	12.56	12.56	12.56	12.56	12.56
9	9.42	9.42	9.42	9.42	9.42	9.42	9.42	9.42
6	6.28	6.28	6.28	6.28	6.28	6.28	6.28	6.28
3	3.14	3.14	3.14	3.14	3.14	3.14	3.14	3.14
	SO4A-2	SO4A-3	SO4A-4	SO4A-5	SO4I-1	SO4I-2	SO4I-3	SO4I-4
15	290	435	580	725	301	602	903	1204	initial live cells
12	290	435	580	725	301	602	903	1204
9	290	435	580	725	301	602	903	1204
6	290	435	580	725	301	602	903	1204
3	290	435	580	725	301	602	903	1204
	SO4A-2	SO4A-3	SO4A-4	SO4A-5	SO4I-1	SO4I-2	SO4I-3	SO4I-4
15	1281.536	1452.355	1824.593	2017.494	2238.316	2160.33	2682.706	2815.268	final cells
12	1200.739	1410.113	1403.444	1531.542	1678.082	1840.565	2072.807	2175.87
9	1030.552	1281.536	1275.025	1229.68	1316.986	1335.536	1707.368	2006.495
6	792.2474	926.4368	1021.271	1249.065	1275.435	1340.181	1629.525	1960.899
3	574.9571	751.3386	815.8027	1140.183	899.9871	1044.822	1261.642	1504.758

Side by side starters Part 1 of 4

Recently I completed collection of data on a set of 42 side by side starters. Before I go into what this data means I figured I would present just the data and methods so that you can mull on this if you want.  The the experiment will be broken into four parts:
1. Daily data collected on month old yeast vs fresh yeast
2. Starting and final results of 40 fermentation with a range of inoculation rates and gravities
3. Analysis of the daily data
4. Analysis of the start and finish data.

The Daily Data

Two15ml test tubes were prepared.  Both had a starting gravity of 9.42°P.  One was inoculated with 58 million cells taken from an active starter.  The second was inoculated with 60 million cells taken a slurry that had been in the refrigerator for one month.  Measurements were taken approximately daily and the date and time was recorded with each measurement.  These measurements included a refractometer measurement and a cell count with viability staining.  At the top of this post is a graph of the results.  The "active" description represents cells taken from the active starter, while the "inactive" represents cells taken from the refrigerator.  SBW is the sugar by weight.  This is the converted refractometer measurement using the equations derived in earlier posts.  The "eq" plots are a simple equation to show the relationship between consumed sugar and cells produced.  For the active culture this is 10 times the sugar consumed, and for the inactive it is 15 times the sugar consumed.

Raw Data

Day	Active ABV	Inactive ABV	Active SBW	Inactive SBW	Active Live cells	Inactive Live cells
0.02			9.42	9.42	59.8	51.2
0.88	2.279169	2.279169	4.71	4.71	141.9	152.7
1.17	3.038892	3.418754	3.14	2.355
1.22					170.17	163.9
1.66	3.342781	3.722643	2.512	1.727
1.83	3.190837	3.874587	2.826	1.413	177.1	178.2
2.12	3.494726	4.178477	2.198	0.785
2.17	3.494726	4.102504	2.198	0.942	152.9	199.1
2.63	3.418754	4.178477	2.355	0.785
3.21	3.266809	3.95056	2.669	1.256	145.86
3.22	4.558338	4.558338			168.3	172.7
4.08	4.558338	4.558338			176	215.6