Saturday, February 23, 2013

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


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