High FG

[AN_TKE]

Forgive me if this thread is a bit redundant, but I can't seem to find the answers to my questions in many of the other similar threads on this subject.

I have brewed a few high OGs lately and I'm not able to get down to the target 1.0teens I'm looking for or indicated by the recipe. I'm measuring SG with a refractometer and I am mashing at 150 to 152+/-. My questions are:

1. I strain and funnel chilled wort out of the boil kettle into the fermenter. The fermenter has a good head of foam on it by the time the kettle is empty, telling me I probably have enough O2 for the yeast. I am relying on the idea that the strainer thins out the wort enough to allow O2 to be absorbed to satisfy the yeast. Anyone have any thoughts on my method and the importance of O2? I hesitate to add an O2 injection method if I don;t have to.

2. Is a yeast starter really important? If I am just pitching one Wyeast packet or White Labs vial into into a high gravity 5.75 gal bucket of wort, will that impact really FG? I have had the feeling, until experiencing inadequate attenuation, that the beefing up yeast cell count to handle high wort OG is just a nervous and unnecessary practice. After all, doesn't the yeast just eat and eventually multiply into a greater population than a starter would ever provide? Or is it important for some reason to hit the sugar with as much yeast as possible to allow more sugars to be consumed simultaneously?

3. Is there something I am not thinking of? If my mash thermometer is off and my temp is too high, will that result in too many unfermentable sugars?

Thanks for any help.

 

[El_Exorcisto]

refractometers get squirrelly in the presence of alcohol

There is a chart somewhere to account for %abv to correct your gravity reading.

 

[PT Ray]

You need to pitch enough yeast for proper attentuation.

 

[kanzimonson]

1) Look at any brewing book and you'll see that simply picking up oxygen from air is not enough oxygen for yeast metabolism in high gravity beers.

2) I used to have the same logic about pitch rates when I started brewing - then I read books and listened to the brewing network and they informed me how wrong I was. High FG is a perfect indicator than you're not pitching enough.

3) The aforementioned refractometer measurement might be a problem.

 

[AN_TKE]

Thanks for the feedback. How do you guys oxygenate? I'm puzzled about the refractometer issue too. Can anyone elaborate?

 

[Yooper]

Thanks for the feedback. How do you guys oxigenate? I'm puzzled about the refractometer issue too. Can anyone elaborate?

Well, refractometers are great for measuring the amount of sugar (in brix) of wort or unfermented fruit. But for anything with alcohol in it, well not so much.

Use a refractometer for unfermented musts and wort. Not for beer or wine that has already begun fermentation.

Alcohol has a brix of less than 0 and an SG of less than 1.000. so it messes up any readings you might take after fermentation has begun.

There are some calculators that can help compensate for this, but they are not accurate.

So, refractometer is for must/wort. Hydromter is for beer/wine or once fermentation has begun.

 

[Bigscience]

If you're not compensating once you start fermenting, your values will look high. I use one to track my fermentations to see if they are still moving along and always do an end verification with a hydrometer. I've had good luck using the More Beer spreadsheet here:

http://morebeer.com/learn_vids/vids_refract

Also, pitch more yeast and invest in an Oxygenation System. I like the pure O2 but others say they have good luck with an air pump. 60sec of O2 with a fine level of bubbles coming to the surface works well for me. Also remember that you can over do it with the pure O2.