Exp.1: “Yeast amount comparison – 300ml Vitallity starter vs. 1200 ml Vitallity starter”

The first experiment on “The Bubble Logger Project” blog is to compare the yeast pitching rate. The Bubble Logger give both yeast activity measurements and SG estimate, hence, we will have good details on how the fermentation is affected by high or low amount of pitched yeast. This experiments is carried out by brewing one batch and split it into 2 fermenters of equals size and hence only varies the parameter of amount of yeast added.

The way I brew is by overnight chilling where I simply let nature takes it toll and hence this give the possibility to make a vitality starter as I pitch the yeast more or less 24 hours after turning heat off, and hence in this experiment we see how 4 times more slurry of a dry yeast “vitallity started” treated yeast behave in a 1:4 situation.

The other part of this experiments is to see how “re-using” hops from major dry hopping spins out. As I often use 400g hops for a NEIPA (20L) and find the hops rather “dry” after examining them after use, I thought how about re-use this high amount of hops (I use keg metal hop containers and only inset 100g at each). So the other part of this experiment is to see how re-use hops turns out (done it once before). In this experiment we re-use 150g there have been dry hopped for 6 days and hence assumes 25% reduction in bitter units accordingly of the used hops.

RE-Use Sweet IPA Hop´s – Batch 1 (300ml) + Batch 2 (1200ml)**

American IPA – 5.4%

Vitals
Original Gravity: 1.057
Final Gravity: 1.018
IBU (Tinseth): 46
Color: 16.5 EBC 
Amounts (liters): 10L + 10L

Mash
Strike Temp — 71.3 °C
Temperature — 68 °C — 150 min

Malts (2.625 kg)
2.2 kg (83.8%) — Avangard Pale Ale Malt — Grain — 5.9 EBC
300 g (11.4%) — Weyermann Munich I — Grain — 14 EBC
125 g (4.8%) — Caramel/Crystal Malt — Grain — 118 EBC

Boil: 30min

Hops (80.8 g)
40.4 g (29 IBU) — Citra 10% — Aroma — 30 min hopstand @ 90 °C
18.8 g (5 IBU) — Cascade 4% — Aroma — 30 min hopstand @ 90 °C
10.8 g (5 IBU) — Amarillo 6% — Aroma — 30 min hopstand @ 90 °C
10.8 g (8 IBU) — Simcoe 10% — Aroma — 30 min hopstand @ 90 °C

Yeast
15 g — Mangrove Jack’s M44 US West Coast Yeast VITALLITY started 24h (1.5L + 15g dry yeat) – splitted into 300ml and 120ml

**Orginal recipy: https://share.brewfather.app/B5CXBhJziDBZU9

Results/Conclusion

The 3 following dataset was generated by the Bullble-logger : Blops pr. min (BPM), Gravity and Temperature. Green lines is from HIGH yeast of 1200ml and Bue lines is for LOW yeast amount of 300ml.

Figure 1: Blops pr Min (BPM) for HIGH and LOW yeast amount. (Data re-calcualted).

Based on the Blops pr. Min (BPM) we can conclude:

  • The HIGH yeast (Green line) start around 5 hours before the same activity is seen at the LOW yeast (Blue line).
  • The HIGH yeast have a higher intensity even we account for a small differeny airlocks dynamics (bubble-genration).
  • THe LOW yeast on the other hand have a longer fermentation and ends 8-12 hours later.

If we also look at the SG in Figure 2 we agian see the LOW yeast is delayed in activity:

Figure 2: The Gravity over time of HIGH yeast amount (1200ml) and LOW yeast (300ml). (Data re-calcualted).

From the last Figure, Figure 3, for temperature we can also see someting interesting:

  • The High yeast faster got warmer suporting the High yeast did start ealier.
  • Secondly the HIGH yeast also got a bit warmer than the slow yeast also supporting the claim the HIGH yeast did reach relativity higher BPM and had a higher intensity.

Discussing:

Where or not a ration of 1:4 is the right to really show big difference between high or low yeast is something I need to consider. Maybe 100ml vs. 1400ml would have been more profund. The delay of 8-12 hours before the LOW yeast amount got to 80-90% of FG, is i my mind not something there is really important. One thing I did not expect was the HIGH yeast got almost 3.5 Degree over ambient temperature and nearly 1 degree higher than the LOW yeast.

Finally, as I have been dooing “Vitality starting” for my brews for the last 2 years, I do know they get completed very fast, but still it is remarkable both brews, either HIGH or LOW yeast amount, did complited 90% of the fermentation in just under 24 hours (HIGH yeast) and the LOW yeast was 36 hours on the same. Both very fast.

I guess next brewing should be 5g dry “Vitality started” vs. 5g Dry directly in bucket?

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