I am planning on brewing a barley wine as soon as the weather cools off enough so I can maintain a fermentation temp of 65-70 deg. F. It will have an OG of approximately 1.110. I have purchased 3 packs of Nottingham yeast (11 gm per pack) and am wondering if this should be enough yeast for 5 gallons. I have been told that it may be too much yeast but I want enough to promote a good healthy ferment. I will aerate the wort well with pure O2 and add any fermentation aids that you may suggest. Thank you for sharing your expertise.

-Harlan Nilsen

RESPONSE:

It looks like you are going in for a very high gravity fermentation, which means that you will need to increase the yeast inoculum and provide adequate nutrient supplementation. A 11 gram package of Nottingham can readily handle five gallons of 1.048 OG wort, but would have a struggle handling 1.110 OG wort. It would take two packets to comfortably handle this high gravity wort. There is a general rule of thumb for inoculating a high alcohol (high gravity) fermentation: one million yeast cells per ml. of mash per % sugar, Brix or Balling. In the distilling and wine industry, OG, Brix and Balling equals % sugar.

This is not true in the brewing industry. Part of the gravity is not fermentable sugars, however, during the first part of the fermentation, the osmotic effect is similar on the yeast growth. Yeast do not multiply in high gravity as well as they do in low gravity, so you have to make up the difference by adding a larger inoculum.

Please give special attention to the Nottingham yeast rehydration procedure written on the package. Success or failure often starts with the rehydration procedure. I am not sure how you achieved the 1.110 gravity wort; mashing, malt extract or pure sugar, so I cannot give you an exact answer regarding the amount of nutrients that will be required. Pure sugar adjunct contains no nutrients for the yeast and will require the most supplementation from a well balanced nutrient source. For your interest, yeast require 30% more nitrogen source to ferment a 25% sugar juice than it does a 20% sugar juice. This shows you the importance of giving careful attention to nutrient supplementation. I would add 10 grams of a well balanced nutrient like Fermaid K / 5 gallons wort.

Regular gravity wort fermentation require about 8 ppm O2. As you go up in gravity, the O2 requirement increases. You will need about 15 - 20 ppm O2. How do you achieve this is a good question. Large breweries, wineries, distilleries and research centers have good metering devices $$$. It takes about an hour of pumping air, using an aquarium pump, through a porous ceramic stone and just a few minutes using pure O2. I have always been leery of pure O2. You have to make sure that it is not hospital grade. Some hospital grade O2 contains a fungicide. Perhaps some of your colleges can give you advise regarding aeration equipment and timing. Let me know how your barley wine turns out.

Dr. Clayton Cone