Souring Sources, Calculating Carbs, & Storing Hops
Q. I recently watched one of your BYO+ videos about making sour beer. The suggestion to use kimchi for souring beer blew my mind! I’m already making my own kimchi, so I will definitely try this. Here are my questions: 1. Is there any taste difference between using kimchi and the Lactobacilli that I can purchase from a lab? 2. If kimchi works, what about traditionally soured dill pickles, e.g., Strubbs?
Gord Maxwell, via Live Chat
A. I recently talked about this during a BYO Live Chat and thought it would be worthwhile to share some expanded thoughts in writing. Let’s start with the idea of using kimchi as a source of bacteria for making sour beer. As a probiotic-rich food, kimchi is a well- established source of various microorganisms believed to promote gut health (Indigenous Fermented Foods for the Tropics is a great reference on this). These microbes, many of which are lactic acid bacteria, also happen to be useful in the production of sour beer.
The primary organisms responsible for kimchi fermentation belong to the gram-positive, acid-producing Lactobacillaceae family of bacteria, often referred to more simply as lactics. This large and diverse group of bacteria is naturally found in many places, including grains, fruits, vegetables, and even in puddles of fermenting spilled milk. One particularly interesting trait of lactics is that many are heterofermentative, meaning they produce multiple byproducts during fermentation. Depending on fermentation conditions, these byproducts typically include lactic acid, ethanol, and acetic acid. This contrasts with homofermentative lactics, which mainly produce lactic acid. That’s enough nerding out for now.
These days, most sour beers are produced using one of two general approaches: Either by purchasing lab-grown cultures or by channeling your inner Tarzan and wrangling wild bugs. Traditional sour beers rely heavily on the Tarzan method, where wort is naturally inoculated by airborne microbes, ingredients, and the unique microflora found in the brewing environment. One of the best-known examples of this method is used by Brasserie Cantillon in Brussels, Belgium. They are legendary for their exceptional wild ales, which have been brewed using largely unchanged techniques for nearly a century. Their brewery sits tucked away in a charming neighborhood surrounded by butcher shops, cafés, and rows of townhouses, blending the old-world craft of spontaneous fermentation with the bustle of modern life.
In more recent years, brewers have adapted this traditional approach by using fermented foods — especially yogurt and kefir — as alternative sources of bacteria for kettle sours. Although these cultured dairy products are often made with blends of commercially available bacteria, to the brewer they are still considered somewhat wild, since the exact composition of the cultures isn’t usually known when added to wort. This adds a layer of unpredictability, which can be both exciting and risky.
Over the past 25 years or so, access to specialty cultures of bacteria and yeast has grown dramatically. Today, brewers looking for consistency and control in their funky beers have a wide range of commercial options. In the early days, most of these lab cultures were blends of organisms found in traditional Belgian lambics or blends intended to approximate bugs found in lambics. As time went on, the push for more predictable and faster souring methods led to the rise of kettle souring. This process is popular because it allows brewers to keep the souring bugs contained in the brewhouse, rather than introducing them into the fermentation cellar where cross-contamination is a concern.
Because malt is such a rich source of lactic acid bacteria — including Lactobacillus delbrueckii, which is homofermentative, and Lactobacillus plantarum, which is heterofermentative — many early kettle souring techniques relied on bugs cultured directly from malt. Today, however, brewers can easily purchase pure lactic cultures from yeast labs. These have largely replaced wild-cultured sources, especially for brewers seeking repeatability and ease of use.
More recently, lactic acid–producing yeast strains have gained popularity. Lachancea thermotolerans is a naturally occurring yeast that produces both lactic acid and ethanol and is now available to homebrewers and commercial brewers from yeast labs such as Escarpment Labs and Lallemand. Lallemand also offers a genetically modified Saccharomyces cerevisiae strain known commercially as Sourvisiae. This strain has been engineered to express the gene for lactate decarboxylase, an enzyme that converts pyruvate to lactic acid. The main advantage of using Lachancea or Sourvisiae in sour beer production is the simplified process compared to kettle souring, with no bacteria introduced into the cellar.
All of this helps explain why the idea of going Tarzan with kimchi as a source of lactics is so appealing for brewers looking for an adventure. Fresh kimchi juice contains a healthy population of lactic acid bacteria. According to the kimchi chapter in Indigenous Fermented Foods from the Tropics, cell densities in kimchi typically range from 100 million to 1 billion cells per milliliter. That’s an ideal range for brewers looking to propagate a strong bacterial culture for use in beer. You’ve got plenty of biological firepower in even a small splash of kimchi juice to propagate for use in brewing.
Kimchi is just one of many fermented foods that can be used to wrangle bugs for making sour beer. My general advice is to start with foods that taste good to you. If you wouldn’t eat it, don’t brew with it. Live sauerkraut, buttermilk, and dill pickles are all viable sources of lactics.
One final, important tip: If you’re working with heterofermentative lactics, avoid creating conditions that lead to the production of acetic acid (aka vinegar). These bacteria only make acetic acid in the presence of oxygen, so be sure to minimize oxygen exposure during the souring phase. A sealed vessel and a good dose of CO₂ headspace can help you keep things clean and crisp.
Q. Two nutrient analytics labs tested my first attempt at a low-carb beer and showed all sugars and carbs as less than 1 g per 100 mL. Yet it does spike my blood sugar severely. According to Brewfather, my recipe should have 3.6 g of carbs per 100 mL. Are the labs missing some type of sugar or carbs?
Pieter de Weerdt
Via Live Chat
A. This is a great question that affects beer lovers of all sorts, especially those of us who keep a watchful eye on our blood glucose levels. Unfortunately, I cannot provide any specific details about the data you received from the labs who ran your testing with the available information. It does seem unusual that beer with 1 gram of carbs per 100 mL would cause a spike in your blood glucose. As a comparison, commercially produced light/low carb beers brewed in the U.S. contain between 0.7 – 1.9 grams of carbs per 100 mL of beer. Although I cannot provide information about the past, I can comment on differences between expectations and measured values, how to estimate carbs, and a few ways to reduce them in beer. Let’s begin with predictions.
Recipe calculators use predictive equations to estimate alcohol and residual extract based on the original gravity and predicted final gravity. Because malt specifics, mashing particulars, and water chemistry can all affect wort fermentability, predicting final gravity is not much more than a guess. Furthermore, yeast strain, pitching rate, and yeast nutrients influence residual carbohydrates left behind after fermentation. In my experience, making assumptions about fermentation is not as approximate as assumptions about wort composition. That said, predicting final gravity is approximate.
A better way to estimate alcohol and residual carbohydrates is to use a model that uses both original extract/gravity, and apparent extract/gravity. Two estimates I feel comfortable using are the following developed by Gary Spedding because I bumped these calculations against known beer data and they provide solid estimates. Although the original publication in Brewers Digest cannot be found online, this article in Brewers Journal contains Spedding’s calculations. There are two equations in this article for alcohol by weight (ABW) and it is the second that should be used (I converted equations from the original reference into a spreadsheet years ago and know that there was some sort of editorial confusion in the referenced article).
Real Extract = (Original Extract × 0.1948) + (Apparent Extract × 0.8052)
Alcohol by Weight = 0.8052 x (Original Extract-Real Extract) / 2.0665 – (1.0665 x Original Extract / 100)
Here is what the math above reveals about a typical beer-flavored beer with a wort gravity of 11 °Plato and a final gravity of 2 °Plato. Note that I have not included specific gravity equivalents because the equations above use Plato for the calculations, but for those curious we are talking about 1.044 OG and 1.008 FG. Also note that the units on Plato are grams extract per 100 mL of beer or percent by weight.
Real Extract = (11 x 0.1948) + (2 x 0.8052) = 3.74 °Plato
Alcohol by Weight = [0.8052 x (11 – 2)] / [2.0665 – (1.0665 x 2/100)] = 3.5% ABW (g/100 mL)
Alcohol by volume is equal to ABW / 0.79 (the density of ethanol), and 3.5% ABW equals 4.5% ABV. I only show ABV because it is the most common unit used to express alcoholic strength in beer, wine, and spirits. However, when it comes to calculating grams of residual extract and calories, percent by weight is the value to use.
The term real extract is used to define dissolved solids in beer, which are mainly comprised of carbohydrates but also include protein, minerals, and hop acids. For your inquiry, it is safe to assume that 100% of the real extract can be attributed to carbs because that slightly overestimates the value.
We have determined that beer with an OG of 11 °Plato and a final gravity of 2 °Plato contains 3.7 grams of carbs per 100 mL of beer and 3.5% ABW. Carbs contain 4 kcal/gram and alcohol contains 7 kcal/g, giving the beer in this example 39.3 kcal/100 mL of beer or 140 kcal per 12-oz. (355-mL) serving.
In my experience, a lab analysis should provide data that is similar to what is calculated above provided you are producing beer that falls into the typical range of beers found in the market. Spedding’s calculations are based on beer data and do not work for completely fermentable solutions. Without knowing the original extract and apparent extract of your beer, I don’t know if the Brewfather prediction is off or if the labs are off. Run the numbers to see which set of data seems most plausible.
I am guessing from your question you may use a continuous blood glucose monitor. I use one of these devices and have learned a lot about how different foods and beers affect my blood glucose. I feel fortunate to have discovered that my blood glucose was abnormally high a few years ago and to be successfully controlling things with a combination of diet, medication, and monitoring. One thing I learned is my body reacts differently to some beers. When I drink non-alcoholic beers produced using maltose-negative yeast strains, for example, my blood glucose usually spikes because these beers contain all of the maltose and maltotriose that comes with mashing. I also have noted spikes when drinking “normal” beers that have above average final gravities. One hunch that I have with some of these beers is that they have been fermented with yeast strains that do not ferment maltotriose. Unfortunately, this property of yeast strains is not widely published. It is known, however, that many English strains popular among the haze-crazed crowd do not ferment maltotriose.
Methods to lower carbs in beer include extended mash rests in the 140–145 °F (60–63 °C) range, the use of exogenous alpha amylase or amyloglucosidase in the mash or fermenter, substituting sucrose or dextrose/glucose for a portion of malt or malt extract to increase wort fermentability, brewing lower gravity beer styles, selecting high-attenuating yeast strains, and taking advantage of hop creep to dry beers out.
Q. What is the longest you would store Hops in the freezer? Would the max storage time be different for bittering vs. aroma hops?
Ken Grace
Via email
A. This question has two very different answers depending on the source of the hops. Let’s start with pelletized hops sold to commercial breweries. These hops begin their journey at the farm, where tall bines are cut from the fields and the cones are separated using a picking machine. Although a small number of farmers now use hop combines that cut, pick, and separate leaves and bines from cones, most still use picking machines housed in buildings typically referred to as picking sheds. Once the picker has disassembled the cones, leaves, and bines, a system of belts and blowers separates out the cones.
The next step is hop kilning, where hot, dry air reduces the moisture content to below 8%. After kilning, the dried hops are stored in large piles to allow the moisture to equilibrate. In most parts of the world, the hops are then compressed into bales. Before pellets became the norm, this was the end of the line for most hops: Bales would be stored in warehouses — often warm ones — before being shipped to breweries. It was U.S. brewers who demanded refrigerated hop storage. In fact, U.S. hop processors routinely store bales in freezers, whereas German processors typically store them in refrigerators at 36–41 °F (2–5 °C).
Because most hops today are pelletized, bales destined for pellet production are usually stored only briefly before being broken apart using a piece of equipment called a bale breaker. The cones are then milled into powder using a hammer mill. The powder is typically blended in a ribbon-style mixer to reduce variability between bales, then compressed into pellets using a forming die. These days, forming dies are cooled with liquid nitrogen and some processors even cool the hop powder prior to forming. Finally, the pellets are packaged in foil bags. The current standard is to flush these bags with nitrogen gas to create a modified atmosphere that reduces oxidation during storage. For many years, vacuum packing was common, but this method makes the bags prone to damage and can cause pellets to clump together into hard-to-handle masses.
The foil bags of hop pellets are then boxed, palletized, transferred to cold storage, and kept there until shipped to breweries or into distribution channels. Depending on the variety — some hops have better storage properties than others — and the intended use, hop pellets can be stored cold for up to six years. In general, pelletized aroma hops start to fade after 2-3 years of storage and bittering hops can hold their brewing value up to about six years. Breweries equipped with lab instruments and trained sensory panels routinely sample and analyze their inventory to determine how best to use it. Because hops are used exclusively in beer, breweries contract with growers to ensure a reliable supply. When aroma hops become unsuitable for brewing, brewers may repurpose them for bittering or take the loss. One major advantage of hop extracts is extended shelf life, which is why many larger breweries convert a portion of their inventory into extracts shortly after pelletizing (most extract facilities are designed to process pellets, which are more compact than cones).
I know I haven’t answered your question yet, but it’s important to understand how pellets are produced and packaged. The issue is this: Pellet bags typically contain 11, 22, or 44 pounds (5, 10, or 20 kg) of hops. Hops sold in the homebrewing market, by contrast, usually come in 1-oz. (28-g) packages. So the obvious question is: How are these 1-oz. (28-g) bags produced?
Typically, they are repackaged from larger bags that are labeled with critical information such as the harvest year, the processor (the company that converts bales into pellets), a lot number, and sometimes a QR code linking to hop analytics. However, not all repackaged pellets retain this vital information. For example, a commercial-sized bag of 2024 Cascade hops labeled with 8.5% alpha, 6% beta, and 1.5% oil might simply become a bag labeled “U.S. Cascade Hops” with a general alpha acid range of 5–9%.
Hops sold to homebrewers are somewhat analogous to growlers or CrowlersTM of beer. While it is entirely possible to repackage hops without increasing oxygen exposure, the risk is higher. This alone likely shortens the shelf life of homebrew hops compared to those sold to commercial brewers. Another issue is the packaging. Foil bags offer excellent gas barrier properties assuming the seal is perfect and there are no pinholes. Plastic bags, on the other hand, offer poor barrier protection, meaning that even a vacuum-sealed plastic bag can still allow oxygen ingress over time.
My advice is to use hops as soon as possible after purchasing, unless they are packed in foil and clearly labeled with the crop year and processor. The challenges of repackaged hops are well understood, and many hop processors serving the homebrew market have responded by labeling their products with the same information as packs sold to commercial brewers.
Hops do go on sale, and good deals can be found. I love a bargain and feel confident buying discounted hops if I know they were packaged by a reputable processor and properly stored throughout their life. That last piece, storage history, is nearly impossible for any buyer to verify, whether homebrewer or pro. That’s why it’s good brewing practice to smell your hops before use. If you open a bag and something seems off, it’s your call: Repurpose the hops for bittering or make the executive decision to toss them.
