Dear Mr. Wizard,
I recently brewed an old ale with an OG of 1.082 and an FG of 1.015. During the last 10 minutes of the boil, I added about 12 ounces (340 g) of maple syrup. The pre-fermentation sample to obtain the OG had a very nice maple aroma and flavor to it. I siphoned the beer into an aging vessel for some long-term storage and am now considering my options. Given the high alcohol content, I want to bottle it and drink it sparingly so that I can see how it matures over time. My intent is to have a low volume of carbonation, say on the order of 1.5 using maple syrup so that I can reintroduce that aroma and flavor. My understanding is that maple syrup is sucrose, and to obtain a CO2 volume of 1.5 in 5 gallons (19 L), it would require approximately 4 ounces (113 g). The final amount in the aging vessel is about 41⁄4 gallons (17 L). What adjustments do I need to make given that I am using maple syrup in liquid form? How should I be measuring this and what amount is appropriate for 41⁄4 gallons (17 L)?
Wizard responds: I assume that the maple syrup aroma faded some during fermentation and that is the reason why you wish to add more maple syrup to the beer at the time of bottling. I’m not sure how you did your calculation and want to walk through a fairly easy method used to calculate priming sugar requirements. Step one is to measure carbonation level in grams per liter instead of volumes. One volume of carbon dioxide is roughly equivalent to
2 grams of carbon dioxide per liter. So in your case you want 3 grams (0.12 oz.) of carbon dioxide per liter of beer and you have 16 liters of beer. This means that you want to get 48 grams/1.7 oz. (3 x 16) of carbon dioxide in your beer by fermenting sucrose from maple syrup. When sugar is fermented by yeast, ethanol and carbon dioxide are produced. Carbon dioxide represents 49% by weight of the sugar. If you want 48 grams (1.7 oz.) of carbon dioxide you will need 99 grams (3.5 oz.) of sugar (48 ÷ 0.49 = 99).
You want to use maple syrup and need to take into account the water contained in the syrup. Maple syrup has standards and most maple syrup has a concentration of 66 °Brix. The Vermont grading standards are a little different and Vermont maple syrup is a little more concentrated. In any case, if you know the Brix of the syrup you are using you can calculate the weight of syrup required by dividing 99 grams (3.5 oz.) of sugar by 0.66 (assuming 66 °Brix) and now know that you need 150 grams (4,252 g) of maple syrup. The 4 ounces (113 g) you refer to is in line with my 99 grams (3.5 oz.) and it looks like our methods are in agreement. The adjustment you need to make requires the 66 °Brix correction factor.
The above can be simplified into the following: Required syrup (grams) = liters of beer * desired carbon dioxide produced during conditioning ÷ 0.49 ÷ 0.66. This equation can be used for any priming problem simply by adjusting the value 0.66 to the sugar concentration of whatever priming sugar you plan on using.
In my experience, many of the nuance aromas associated with whatever special ingredient added to beer is often lost in primary fermentation. If the ingredient is added to the kettle then the volatile stripping can be even more pronounced. We brew an exceptional coffee stout at Springfield Brewing Company (OK, I’m biased, but it’s really delicious) and the best way for us to get the intense coffee aroma in our stout is to add the coffee to the beer after fermentation. I think the subtle nutty notes of an ingredient like maple syrup will certainly be retained by the method you suggest!
Dear Mr. Wizard,
I’m trying to make sense of BYO’s latest article on yeast pitching rates and correlate it with yeast suppliers’ data. The rule of thumb is 1 million cells/ milliliter /
°Plato. I get that. However, when I go to Wyeast Labs (www.wyeast.com), they not only reference this formula, but also indicate the following interesting points about their Activator product:
1. Each package contains >100 billion yeast cells
2. Each package is designed to successfully ferment 5 gallons of wort with an SG ≤1.060 (or 15 °P)
When you apply the rule of thumb to the second bullet above, you are led to believe that each smack pack contains 280 billion cells (not 100). Are they not following the very rule of thumb they recommend? I suppose 280 billion is greater than 100 billion, but do I really want to purchase a product that is only guaranteed to have ~1⁄3 of the yeast cells I need for my 1.060 wort?
Wizard responds: I went to the Wyeast Web site to do a little bit of recon before answering this question. I found the site very informative and did see much of the information described in your question. What I could not find was any reference to the general rule you cite in your question. However, there is a chart on pitching rate that you may find very useful. Although at first glance the information on the Wyeast Web site seems inconsistent with the assumptions you make in your question, pitching rate is not black and white and the “rule of thumb” pitching rate of 1 million cells/ liter/°Plato is a rule of thumb. If there is no room for a range of pitching rates companies like Wyeast could only satisfy one type of customer, for example the 12 °Plato group, with their yeast packets.
So here is the real scoop about pitching rate. Commercial brewers use a rate that ranges from about 5 million cells/mL to about 20 million cells/mL. The rule of thumb for a 12 °Plato wort dictates a pitching rate of 12 million cells/mL, which is in the middle of the range. In general, ale brewers who want ales with more pronounced esters pitch on the lower end of the range and ferment warmer. Lager brewers tend to pitch at higher rates and ferment cooler. And both ale and lager brewers increase pitching rate with their higher gravity beers. Remember that most of the beer brewed in the world is lager so the rule of thumb is heavily influenced by lager brewers.
It does seem that the minimum cell density of 100 billion cells per packet tends towards the low side of the typical range of pitching rates. But these packets also have an activator to get things metabolically rolling and this is factored into the amount of cells in each packet. Another item discussed on the Wyeast Web site is propagation. If you want to pitch at a higher rate you can propagate or add a second packet of yeast. Like most things in brewing you can spend a lot of time and effort trying to follow textbook rules and even monitor the process to verify that you are indeed following the rules. For example, if you had a microscope and hemocytometer you could do yeast counts to monitor pitching rate. And you can also taste your beer and ask the question, “did everything go OK?”
If everything did not go OK, and your beer suffers from faults that are too numerous to count, then you probably need to carefully evaluate your whole process. This is not normally the case and some problems are often suspected before finishing the beer and tasting. If you fear that you are under pitching there are several symptoms associated with under pitching that are pretty easy to spot. Slow, lagging fermentations are one common symptom and beers with odd aromas are another. If you are using these yeast packets without problems then I fear you have early signs of becoming a homebrewing hypochondriac. Not to worry, this is not an irreversible illness and recovery is possible. If you are having problems associated with under pitching, increase your pitching rate and see if the problems go away.
I think I have become more grounded with experience. In my younger and more boisterous days I was sometimes guilty of thinking bad thoughts such as, “those guys, I know what they’re doing, they’re trying to confuse the facts and trick me into thinking that [fill in the blank].” That line of thinking may work for some consumer products, but doesn’t hold much water with art supplies.
Yeast is an art supply for the brewing artist. Some of us make rock-solid beers by pitching 5 million cells per mL and others make rock-solid beers by pitching 20 million cells per mL (that must read like total geek speak to the non-brewer!). I don’t believe any yeast supplier does anything to confuse or “cheat” their customers and they pick a product to market that hopefully fits the needs of most of their customers. If your needs are different, use the information about the product to make the necessary medications.