high OG high FG?

[pugsby]

Hi all,

New brewer here. This is my second/third brew with 2 small batch experiments.

Both have been fermenting for 4 weeks with W-34/70 Saflager Yeast between 12-15 C (Canberra).

Brew 1
OG: 1.048 (Light DME, no specialty grains steeped)
FG: 1.014 (after 4 weeks)

Brew 2
OG: 1.062 (Light DME, steeped with [SIZE=10pt]black malt, 30g pale crystal malt, 30g medium crystal malt, 30g dark crystal malt)[/SIZE]
FG: 1.018 (after 4 weeks)

70-71% attenuation for both (vs 83% on the fermentis website for W-34/70).

Is it OK to bottle at these FG?

 

[pcmfisher]

So is that all ldme you are using and nothing else? No kit or anything?

 

[pugsby]

Correct. There is nothing else. Just the dry malt extract bought from CheekyPeak.

 

[TheBlackAdder]

FG seems a little high.

Im assuming 1kg of LDME in how much water?

Have you checked your hydrometer calibration?
If not, use cold boiled water in the tube and check that it is reading 1.000

You might want to pick up some hop pellets or tea bags to add a little more flavour to the brews as well

 

[Kev R]

Are you reading your hydrometer at 20deg C. If your reading at 12deg you will need to take a few points of to compensate?

 

[pcmfisher]

Depends on who made the light malt.
If you do an all Coopers liquid malt brew ie 3kg of the stuff, you struggle to get a lower fg that 1013 - 14.

As bad or worse with the Bintani dry stuff.

 

[pugsby]

A few more questions...

Does steeping with crystal malt add unfermentable sugars and so you expect a higher FG?

In general do you target an apparent attenuation % or the FG number?

 

[Screwtop]

Extract is slightly less fermentable so you should expect somewhat less attenuation than quoted by the manufacturer as the quoted figure would be achievable in perfect conditions.

Conventional pitching rate is 1. For Ales 750000 cells per ml of wort per degree plato. 2. For Lagers 1500000 cells per ml of wort per degree plato

For your Brew 1 OG: 1.048 (11.9 Plato)
(0.75 million) X (milliliters of wort) X (degrees Plato of the wort)
If you had 21 litres of wort then 750000 X 21000 X 12 = 189 billion cells. 189 Billion cells of fresh yeast required or 31.27 grams

Fermentis specs indicate that their fresh yeast contains > 6 x 10^9 /g or greater than 6 billion cells per gram. So a single pack of 11.5g of fresh dried yeast provides 69 Billion Cells. Fermentis suggest pitching 80 to 120 g/hl at 12C – 15°C Lets say we work on 100g/hl or 1 gram per litre. You would need to pitch 21 grams of fresh yeast to 21L of wort.

Deduction: You're not going to achieve maximum suggested attenuation

Brew 2 OG: 1.062 (15.21 Plato)
(0.75 million) X (milliliters of wort) X (degrees Plato of the wort)
For 21 litres of wort 750000 X 21000 X 15 = 240 billion (rounded) cells. 240 Billion cells of fresh yeast required pitch or 39.92 grams.

Even using the Fermentis specs (Fermentis don't mention increasing pitching rate for higher gravity wort) and pitching the maximum (80-120g/hl) rate of 120 g/hl or 1.2 grams per litre. You would need to pitch 21 grams of fresh yeast to 21L of wort.

Again it appears you have underpitched! Most brewers underpitch!!!!!!

So.... Was the yeast fresh? What was the volume of your wort? What was your pitching rate?

Cheers,

Screwy