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Multi-Yeast Tests

I am trying to accumulate data on multi-yeast beers in an effort to understand why we sometimes only get a percentage of the total possible alcohol and why they sometimes don't use up all of the available nutrients. Much of this data is my own, but I have also begun searching the Wiki for other players' data to analyze and re-post that existing data in the same format I created for my own results. For the moment I am only analyzing tests with 2 yeasts (using seal times that excluded all other yeasts and microbes). Once I get a handle on that, I will expand my research to 3 yeast beers and open kettle beers.

Some preliminary findings:

• Yeasts are probably handled consecutively. The first yeast uses up as much of the nutrients as it is going to (more on this later) and then the second yeast uses up what it can, and so on. At the end of the Fermentation phase, the numbers generated by each yeast are added up to generate the totals we see in the finished beer. This is supported in particular by the ending Glucose numbers in many tests, which invariably reflect the 2nd yeast's Glucose Floor number when the beer uses up all the Glucose it can.

This is why I was able to "predict" the results after the fact, by changing the alcohol contributed by each yeast in the spreadsheet until the flavor numbers added up to more or less the observed results. In other words, I don't yet know the rules that would allow me to predict the results before I make the beer, but I can make the spreadsheet numbers match the finished beer results pretty closely afterwards by playing with the alcohol that each yeast contributes until the flavors match.

• The first yeast will often (but not always) use up as much nutrients as it can until it reaches its Max Alcohol limit, or hits the Glocose Floor, the Maltose floor, or the Vitamin Floor. However, in some cases, none of these limits are reached and the first yeast seems to produce only a percentage of the total possible alcohol (often around 70% but it varies). The rules governing why this happens are still not clear.
• If the first yeast has a high MaxAlc number (over 600 or so), then you will often only get a percentage of the total MaxAlc possible from that yeast.
• The second yeast almost never uses up as much of the remaining nutrients as it could. I have seen ranges of 0% to 53% of the total MaxAlc potential on the second yeast. Often plenty of nutrients are left over, but the second yeast doesn't use them all for some reason.
• Using different sealing times to capture the same two yeasts had no effect on the outcome (see my SealingTimes page).
• Different recipes will often result in the exact same total alcohol (and flavors) in the beer as long as there are plenty of nutrients for both yeasts in both beers.

Note: You may notice that my estimates for the flavor amounts generated by each yeast don't always add up exactly to the numbers on the "Totals:" line. This is partly because the numbers were taken directly from my spreadsheet and sometimes they round up or down. Rounding issues with the yeast stats (and perhaps imprecise yeast stats) probably also affect how closely my estimates match the actual beer results. Given these limitations, I got as close to an accurate estimate of the alcohol contribution by each yeast as I could.

Y8 / Y51 Tests

Test 1

This was my first recipe for these two yeasts.

Recipe: 140 Honey @ 24; 35 Light Malt @ 1176

Location:	878, -3376	Yeasts:	Y8 / Y51	Sealed at:	550
Y8 MaxAlc:	992	Glucose Floor:	13	Maltose Floor:	12	VitFloor:	71
Y51 MaxAlc:	755	Glucose Floor:	3	Maltose Floor:	173	VitFloor:	171

Predicted Results:	Alcohol	Color	Vitamin	Glucose	Maltose	Barley	Orange	Bannana	Cherry	Date	Honey	Nutmeg	Cinnam	Tannin	Grassy	Nasty
1st Yeast (estimated):	755						8	56	11	27		8	8			58
2nd Yeast (estimated):	129						39	1	2	2		5	3			2
Totals:	884	52	494	586	350	207	47	57	13	30	2018	14	11	103	62	60
Actual Results:	884	52	495	586	350	207	47	56	12	29	2018	14	10	103	61	59

Test 2

On this next test, notice I changed the recipe but got the same total alcohol (and flavors). Interestingly, the first yeast seems to be Maxing out at the second yeast's MaxAlc number. Is this a coincidence?

Recipe: 35 Honey @ 1176; 50 Light Malt @ 1176; 20 Medium Malt @ 24

Location:	878, -3376	Yeasts:	Y8 / Y51	Sealed at:	550
Y8 MaxAlc:	992	Glucose Floor:	13	Maltose Floor:	12	VitFloor:	71
Y51 MaxAlc:	755	Glucose Floor:	3	Maltose Floor:	173	VitFloor:	171

Predicted Results:	Alcohol	Color	Vitamin	Glucose	Maltose	Barley	Orange	Bannana	Cherry	Date	Honey	Nutmeg	Cinnam	Tannin	Grassy	Nasty
1st Yeast (estimated):	755						8	56	11	27		8	8			58
2nd Yeast (estimated):	129						39	1	2	2		5	3			2
Totals:	884	85	651	3	303	317	47	57	13	30	52	14	11	155	84	60
Actual Results:	884	85	652	3	303	317	47	56	12	29	52	14	10	155	83	59

Test 3

With this next test I used the same recipe and a slightly different seal time (one tick later) and I got the same overall results. Notice I estimated a slightly different contribution for alcohol for each yeast. There is a certain amount of uncertainty in these estimates because of rounding errors in the yeast stats. The fact that the 755 alcohol that I estimated for the first yeast in the last two tests matches the MaxAlc number for the second yeast could just be a coincidence.

Recipe: 35 Honey @ 1176; 50 Light Malt @ 1176; 20 Medium Malt @ 24

Location:	878, -3376	Yeasts:	Y8 / Y51	Sealed at:	544
Y8 MaxAlc:	992	Glucose Floor:	13	Maltose Floor:	12	VitFloor:	66
Y51 MaxAlc:	755	Glucose Floor:	3	Maltose Floor:	173	VitFloor:	171

Predicted Results:	Alcohol	Color	Vitamin	Glucose	Maltose	Barley	Orange	Bannana	Cherry	Date	Honey	Nutmeg	Cinnam	Tannin	Grassy	Nasty
1st Yeast (estimated):	757						8	56	11	27		8	8			58
2nd Yeast (estimated):	127						38	1	2	2		5	3			2
Totals:	884	85	650	3	303	317	47	57	13	30	51	14	11	155	84	60
Actual Results:	884	85	652	3	303	317	47	56	12	29	52	14	10	155	83	59

Y75 / Y58 Tests

Test 4

New location, different yeasts. Almost all of the alcohol (and flavors) seems to come from the first yeast. The only way I can find to explain these results is that the first yeast is using the Vitamin Floor of the 2nd yeast. In other words, Y75 is producing much more alcohol (and flavors) than it should.

Recipe: 80 Honey, 30 Medium Malt @ 1176

Location:	1012, -3269	Yeasts:	Y75 / Y58	Sealed at:	1300
Y75 MaxAlc:	1421	Glucose Floor:	13	Maltose Floor:	192	VitFloor:	88
Y58 MaxAlc:	866	Glucose Floor:	6	Maltose Floor:	228	VitFloor:	4

Predicted Results:	Alcohol	Color	Vitamin	Glucose	Maltose	Barley	Orange	Banana	Cherry	Date	Honey	Nutmeg	Cinnam	Tannin	Grassy	Nasty
Y75 (estimated):	955						27	30	14	14		25	30			19
Y58 (estimated):	7						1	0	0	0		1	0			0
Total Predicted:	962	89	58	6	192	177	27	30	14	14	92	25	30	59	96	19
Actual Results:	962	89	59	6	192	177	28	30	14	14	92	25	30	59	96	19

Test 5

On this next test we have the same location but a different recipe, and now we see the second yeast contributing a bit more. I have retested all the yeast stats and it now looks like both yeasts may be using as much of the nutrients as they can. I will continue to retest the yeast stats for the other multi-yeast tests and see what the new results look like.

Recipe: 70 Honey, 40 Dark Malt @ 1176

Location:	1012, -3720	Yeasts:	Y75 / Y58	Sealed at:	1400
Y75 MaxAlc:	1421	Glucose Floor:	13	Maltose Floor:	192	VitFloor:	88
Y58 MaxAlc:	866	Glucose Floor:	6	Maltose Floor:	228	VitFloor:	4

Predicted Results:	Alcohol	Color	Vitamin	Glucose	Maltose	Barley	Orange	Banana	Cherry	Date	Honey	Nutmeg	Cinnam	Tannin	Grassy	Nasty
Y75 (estimated):	719						20	22	10	10		19	22			14
Y58 (estimated):	227						20	10	7	6		18	3			7
Total Predicted:	946	236	62	6	228	236	40	32	18	16	86	37	25	59	75	21
Actual Results:	946	236	64	6	228	236	42	33	17	16	85	36	24	59	74	21

Test 6

Same recipe, different seal time, same results.

Recipe: 60 Honey @ 1176; 10 Light Malt @ 24; 40 Dark Malt @ 1176

Location:	1012, -3269	Yeasts:	Y75 / Y58	Sealed at:	1200
Y75 MaxAlc:	980	Glucose Floor:	13	Maltose Floor:	192	VitFloor:	87
Y58 MaxAlc:	1026	Glucose Floor:	6	Maltose Floor:	25	VitFloor:	55

Predicted Results:	Alcohol	Color	Vitamin	Glucose	Maltose	Barley	Orange	Bannana	Cherry	Date	Honey	Nutmeg	Cinnam	Tannin	Grassy	Nasty
1st Yeast (estimated):	980						26	30	14	14		25	30			20
2nd Yeast (estimated):	22						2	1	1	1		2	0			1
Totals:	1002	239	483	6	192	247	28	31	14	14	74	26	31	65	101	20
Actual Results:	1002	239	480	6	192	247	29	31	14	14	72	26	31	65	103	20

Test 7

On this next test, different recipe, slightly different results. Something strange happened here. This time my best guess is that I only got about 71% of the MaxAlc from the first yeast, and for a change I got something like 24% of the MaxAlc on the second yeast (vs. about 2% on the previous tests). The second yeast still didn't use up all the nutrients it could have though, and this time it stopped before reaching the Maltose Floor of either yeast. It seems like the second yeast was allowed to do more if the first yeast didn't do as much, but neither yeast was allowed to do as much as it could have with the available nutrients.

Recipe: 70 Honey @ 1176; 40 Dark Malt @ 1176

Location:	1012, -3269	Yeasts:	Y75 / Y58	Sealed at:	1174
Y75 MaxAlc:	980	Glucose Floor:	13	Maltose Floor:	192	VitFloor:	87
Y58 MaxAlc:	1026	Glucose Floor:	6	Maltose Floor:	25	VitFloor:	55

Predicted Results:	Alcohol	Color	Vitamin	Glucose	Maltose	Barley	Orange	Bannana	Cherry	Date	Honey	Nutmeg	Cinnam	Tannin	Grassy	Nasty
1st Yeast (estimated):	699						19	22	10	10		17	22			14
2nd Yeast (estimated):	247						22	11	8	7		20	3			8
Totals:	946	236	70	6	228	236	41	33	18	16	86	37	25	59	73	22
Actual Results:	946	236	64	6	228	236	42	33	17	16	85	36	24	59	74	21

Y96 / Y49 Tests

The data for these two tests comes from Hatnofret's excellent page. Notice that while the recipes for these two tests are different, the total alcohol generated by these two yeasts remains the same. Notice also that in both cases I have basically assumed that the first yeast reached it's MaxAlc first, and this gave a reasonably good approximation of the observed flavor numbers.

Test 8

Recipe: 50 Honey @ 1176; 50 Honey @ 24; 20 Light Malt @ 24; 45 Burnt Malt @ 1176

Location:	1265,-3827	Yeasts:	Y96 / Y49	Sealed at:	1300
Y96 MaxAlc:	573	Glucose Floor:	2	Maltose Floor:	116	VitFloor:	172
Y49 MaxAlc:	1198	Glucose Floor:	12	Maltose Floor:	82	VitFloor:	108

Estimates:	Alcohol	Color	Vitamin	Glucose	Maltose	Barley	Orange	Bannana	Cherry	Date	Honey	Nutmeg	Cinnam	Tannin	Grassy	Nasty
1st Yeast (estimated):	573						860	6	17	43		8	44			13
2nd Yeast (estimated):	629						203	8	13	320		13	15			11
Estimate Totals:	1202	537	472	12	116	22	1062	14	30	363	784	21	59	11	55	24
Actual Results:	1202	537	486	12	116	22	1070	13	33	365	786	21	58	11	56	23

Test 9

Recipe: 50 Honey @ 1176; 50 Honey @ 24; 15 Light Malt @ 24; 15 Medium Malt @ 1176

Location:	1265,-3827	Yeasts:	Y96 / Y49	Sealed at:	1300
Y96 MaxAlc:	573	Glucose Floor:	2	Maltose Floor:	116	VitFloor:	172
Y49 MaxAlc:	1198	Glucose Floor:	12	Maltose Floor:	82	VitFloor:	108

Estimates:	Alcohol	Color	Vitamin	Glucose	Maltose	Barley	Orange	Bannana	Cherry	Date	Honey	Nutmeg	Cinnam	Tannin	Grassy	Nasty
1st Yeast (estimated):	573						862	5	19	44		7	43			13
2nd Yeast (estimated):	629						209	8	13	321		13	15			11
Estimate Totals:	1202	48	388	12	146	105	1072	13	33	364	784	21	58	38	54	23
Actual Results:	1202	48	348	12	146	106	1070	13	33	365	768	21	58	38	54	23

Y48 / Y40 Tests

Test 10

The data for the following calculations came from Matk's excellent Beer Tests page.

Recipe: 112 Honey @ 1176; 8 Raw Malt @ 12

Location:	1021, 3585	Yeasts:	Y48 / Y40	Sealed at:	2200
Y48 MaxAlc:	1026	Glucose Floor:	5	Maltose Floor:	43	VitFloor:	150
Y40 MaxAlc:	971	Glucose Floor:	3	Maltose Floor:	124	VitFloor:	16

Predicted Results:	Alcohol	Color	Vitamin	Glucose	Maltose	Barley	Orange	Bannana	Cherry	Date	Honey	Nutmeg	Cinnam	Tannin	Grassy	Nasty
1st Yeast (estimated):	519						5	131	6	42		14	25			20
2nd Yeast (estimated):	482						13	31	9	9		11	482			40
Total Predicted:	1001	1	220	127	40	17	19	162	15	50	118	24	507	8	42	60
Actual Results:	1001	1	262	127	40	17	20	162	15	50	122	25	507	8	41	58

Test 11

This next test was almost the same as the last, but the recipe had 5 less honey. Most of the stats are the same, as is the total alcohol produced and the flavors, suggesting that the same ratio of alcohol came from each yeast.

Recipe: 107 Honey @ 1176; 8 Raw Malt @ 12

Location:	1021, 3585	Yeasts:	Y48 / Y40	Sealed at:	2200
Y48 MaxAlc:	1026	Glucose Floor:	5	Maltose Floor:	43	VitFloor:	150
Y40 MaxAlc:	971	Glucose Floor:	3	Maltose Floor:	124	VitFloor:	16

Predicted Results:	Alcohol	Color	Vitamin	Glucose	Maltose	Barley	Orange	Bannana	Cherry	Date	Honey	Nutmeg	Cinnam	Tannin	Grassy	Nasty
1st Yeast (estimated):	519						5	131	6	42		14	25			20
2nd Yeast (estimated):	482						13	31	9	9		11	482			40
Total Predicted:	1001	1	216	77	40	17	19	162	15	50	113	24	507	8	42	60
Actual Results:	1001	1	258	77	40	17	20	162	15	50	117	25	507	8	41	58

Y83 / Y73 Test

Test 12

This data also comes from Hatnofret's excellent page. However, in this case, I have to confess I am baffled. Notice that the predicted Date flavor is much less than the actual flavor in the beer. Even if we estimate that all the alcohol came from the 2nd yeast, which has a much higher Date stat, I still only get a total calculated Date flavor of 134. Not sure how to interpret this. For now I have assumed that the first yeast reached its MaxAlc number, like the other tests above where the first yeast has a low MaxAlc. I may need to do additional testing on the yeast stats for both yeasts to make sense of this.

Recipe: 10 Honey @ 1176; 20 Honey @ 24; 40 Light Malt @ 1176

Location:	1250, -3880	Yeasts:	Y83 / Y73	Sealed at:	1200
Y83 MaxAlc:	385	Glucose Floor:	4	Maltose Floor:	100	VitFloor:	26
Y73 MaxAlc:	573	Glucose Floor:	14	Maltose Floor:	194	VitFloor:	169

Estimates:	Alcohol	Color	Vitamin	Glucose	Maltose	Barley	Orange	Bannana	Cherry	Date	Honey	Nutmeg	Cinnam	Tannin	Grassy	Nasty
1st Yeast (estimated):	385						18	22	6	6		4	5			30
2nd Yeast (estimated):	62						1	1	1	19		1	2			1
Estimate Totals:	447	59	337	4	329	236	19	23	7	25	313	4	7	118	64	31
Actual Results:	447	59	337	4	329	236	18	22	6	192	313	4	6	118	63	30

Summary

I have pulled some of the data together into a single table so that it can be viewed side-by-side. I left out test results where I simply used a different seal time and I also left out Test 12 because I am so unsure of what is going on there.

The "Unused Glucose", "Unused Maltose", and "Unused Vitamins" correspond to the amounts left over in the finished beer. This table attempts to show that, although there are nutrients left over above the floors of both yeasts, not all of the alcohol that could be produced is being produced.

Test Name	Yeasts	Max Alc Potential	Estimated Alc in Beer from each Yeast	Estimated % of MaxAlc Potential	Unused Glucose	Glucose Floor	Glucose Above Floors	Unused Maltose	Maltose Floor	Maltose Above Floors	Unused Vitamins	Vitamin Floor	Vitamins Above Floors
Test 1	Y8	992	755	76%	586	13	573	350	12	338	495	71	424
	Y51	755	129	17%	586	3	583	350	173	177	495	171	324
Totals:		1747	884	51%
Test 2	Y8	992	755	76%	3	13	0	303	12	291	651	71	580
	Y51	755	129	17%	3	3	0	303	173	130	651	171	480
Totals:		1747	884	51%
Test 4	Y75	980	955	97%	6	13	0	192	192	0	60	87	0
	Y58	1026	7	1%	6	6	0	192	25	167	60	55	5
Totals:		2006	962	48%
Test 5	Y75	980	980	100%	6	13	0	192	192	0	480	87	393
	Y58	1026	22	2%	6	6	0	192	25	167	480	55	425
Totals:		2006	1002	50%
Test 7	Y75	980	699	71%	6	13	0	228	192	36	64	87	0
	Y58	1026	247	24%	6	6	0	228	25	203	64	55	9
Totals:		2006	946	47%
Test 8	Y96	573	573	100%	12	2	10	116	116	0	486	172	314
	Y49	1198	629	53%	12	12	0	116	82	34	486	108	378
Totals:		1771	1202	68%
Test 9	Y96	573	573	100%	12	2	10	146	116	30	348	172	176
	Y49	1198	629	53%	12	12	0	146	82	64	348	108	240
Totals:		1771	1202	68%
Test 10	Y48	1026	519	51%	127	5	122	40	43	0	262	150	112
	Y40	971	482	50%	127	3	124	40	124	0	262	16	246
Totals:		1997	1001	50%
Test 11	Y48	1026	519	51%	77	5	72	40	43	0	258	150	108
	Y40	971	482	50%	77	3	74	40	124	0	258	16	242
Totals:		1997	1001	50%

Two-Yeast Beer Conclusions

These are tentative observations, conclusions and speculations based on the results summarized above.

• The first yeast will sometimes reach its MaxAlc number, especially if it is a low MaxAlc, but the second yeast never comes close to its potential. The results above show the second yeast maxing out at anywhere from 1% to 53% of its MaxAlc potential. In every case there seems to be at least a little extra nutrients left over (although I want to retest some vitamin floors to be sure). In some cases this may also be due to the second yeast using the greater Maltose Floor number of the first yeast (see below). In other cases, it is not clear why this happens unless the total alcohol for combined yeast beers is capped somehow (see below).
• Tests 1 & 2, Tests 8 & 9, and Tests 10 & 11: Changing the recipe often doesn't seem to result in a different total alcohol (and therefore flavors) produced. As long as there are plenty of nutrients above the floors of both yeasts, they will do as much as they are going to do and stop having produced the same total alcohol.
• Test 4, 5 & 8: Alcohol production seemed to stop in these tests when the remaining maltose reached the floor of the first yeast. Both yeasts were evidently active so it seems like the second yeast was using the greater of the two Maltose Floor values.
• Tests 4, 5, 7: Although these tests all shared the same yeasts, Test 7 didn't follow the pattern described above: some Maltose was left over. Also, the flavor data suggests that a very different % of alcohol was generated by each yeast in Test 7. More testing needs to be done to understand this better.
• Test 10 & 11: These tests are interesting. No Maltose was used by the yeasts, and in both cases some Glucose and Vitamins was left over, but they both produced the same total alcohol. Something in the code seems to be setting a cap on the total alcohol level when more than one yeast is involved. Often we are getting less than half of the total combined MaxAlc possible from the two yeasts, but the total alcohol in the finished beer does not correspond to some percentage of the combined MaxAlc numbers or the average of the two MaxAlc numbers, so far as I can see at the present time.
• Tests 8 & 9: Whereas most of the other tests produced about 50% of the combined MaxAlc in the finished beer, these two tests produced 68% and the second yeast produced by far the highest percentage of the total alcohol in any of the tests. Could this have to do with the low MaxAlc of the first yeast? In other words, the total alcohol cap for a 2-yeast beer may be related to the combined MaxAlc of both beers, but when the first yeast doesn't produce as much of that total, then the 2nd yeast is allowed to do more. This is just speculation so far.