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Brewing Technology: An Old Art Looks Forward

By Scott Jenkins |

Research and development in the brewing industry is peaking, driven by efforts to improve quality, efficiency and sustainability

Within the chemical process industries (CPI), the brewing industry is among the sectors with the deepest historical roots and the most entrenched traditions. While modern brewers are by no means turning their backs on traditional beer making (see box, p. 16), they are increasingly looking forward, relying on advanced science and engineering in never-before-seen ways.

“Research and development in brewing may be peaking now, after a period of decline in the 2000s,” says Kevin Verstrepen, director of the the Leuven Institute for Beer Research (LIBR) at Leuven University (KU Leuven; Belgium; www.libr.be) and professor at the Flanders Institute for Biotechnology (VIB; Ghent, Belgium; www.vib.be).

Technology advancements are allowing brewers of all sizes to pursue improved efficiency and sustainability and find ways to differentiate their products in a crowded and competitive marketplace.

“There is a lot of pressure on brewers to keep coming up with new products with different taste characteristics, and also a large push to reduce resource use, such as water and energy, in the brewing process,” says Brandon Smith, engineering manager with Sierra Nevada Brewing Co. (Chico, Calif.; www.sierranevada.com).

CAVIBEER -full plant view

Figure 1. A brewing method based on controlled hydrodynamic cavitation could save energy and time in the brewing process Photo: Francesco Meneguzzo

 

Optimizing brewing yeast

Beer would not be beer without yeast to ferment the sugars from grain into ethanol. But brewer’s yeast, the single-celled organism Saccharomyces cerevisiae, is a broad classification that encompasses several hundred yeast strains. Yeast is important not only for generating the ethanol in beer, but also for imparting flavors to the drink, through the fermentation byproducts they produce. “I think the most active area of innovation [in the brewing industry] is in the microbiology, and in the fermentation step of the process,” says Verstrepen.

Fermentation is quickly evolving, Verstrepen says, driven by brewers’ desires to improve the quality of their products and the efficiency of their processes “If you can ferment faster or generate higher levels of alcohol, you can use less energy, lower chemical volumes or brew more beer using the same resources,” he says.

“In the past, beer has been brewed with what is really sub-optimal yeast — brewers had to kind of learn their way around the yeasts’ limitations,” Verstrepen says. “But now, using microbiology tools, we are much more able to develop yeast variants that are geared toward certain criteria.” Scientists like those at the LIBR are now able to engineer variants of yeast to better control the metabolic products that create unique flavor profiles in beer. “This is a major evolution in brewing,” Verstrepen says.

Vestrepen’s laboratory has used genetic sequencing to build a collection of yeast variants and to map how the variants are related — a “family tree” of brewer’s yeast. And it is now using that information to create cross-species hybrids yeast in a search for variants that give rise to a new flavor mix. “Often, traditional brewers don’t know what their yeast really is,” Vestrepen says, so we work to identify the exact strain or mix of strains.

Yeasts reproduce sexually by combining spore cells, he explains, and “we now have micromanipulation techniques to generate yeast variants that we want to try in brewing.” This includes the use of Brettanomyces and wild yeast species, in addition to the traditional Saccharomyces strains. Vestrepen uses the analogy of wolves and dogs to describe wild yeast species and brewer’s yeast. “Brewer’s yeast has been domesticated,” he says. “Wolves are to dogs what wild yeast is to regular brewer’s yeast. We’ve had some success generating hybrids between wild strains and domestic ones.”

Screening of the resulting variants remains somewhat of a bottleneck, but the speed at which researchers can test them has been accelerating. “We are taking advantage of robotics advances and ‘lab-on-a-chip’ technologies to sort and screen the resulting variants,” Verstrepen says. “There’s also microdroplet technologies that allow us to ferment tiny volumes very quickly to test whether a variant produces the desired by products and has the desired properties.”

 

Engineering flavor

Knowledge about what influences beer flavor has been available for a long time, “but to an unprecedented degree, we are becoming able to connect specific compounds with the aromas and tastes as perceived by humans,” Vestrepen says, using machine learning and advanced analytical chemistry. Using gas chromatography/mass spectroscopy (GC/MS) and high-performance liquid chromatography (HPLC), among others, “we are learning how individual flavor compounds influence each other when combined into a finished beer.”

A typical project for LIBR would involve selecting yeast variants that produce a specific desired flavor pattern. For example, Vestrepen’s lab worked with a Canadian brewery to breed a strain capable of producing more acetate esters, which produce fruity aromas in the resulting beer. Many projects in Vestrepen’s lab are surrounded by company trade secrets, so no specifics can be discussed.

Meanwhile, at the University of California at Berkeley (www.berkeley.edu), work was recently published by a group of scientists aimed at eliminating the need for hops in beer brewing and replacing them with flavor chemicals produced by yeast. Hops are relatively expensive and require a significant amount of water and fertilizer to grow. Also, the crop can vary in the levels of flavorful oils it contains. Genetically engineered yeast may be able to produce the chemicals responsible for hoppy flavor. A recent paper in Nature Communications describes work by Charles Denby and Rachel Li in which they used the gene-editing technology known as CRISPR-Cas9 to introduce genes from mint and basil plants into yeast strains. The genes code for enzymes that produce the flavor components linalool and genaniol, two components of beer’s hoppy flavor. The duo has formed a company to offer “hoppy” yeast to brewers.

In addition to looking for novel flavor characteristics, the search is on for yeast variants that ferment at lower temperatures, yeasts that allow beer to retain peak flavor longer, or those that can be used for low-gluten beer and no-alcohol beer, notes Sierra Nevada’s Smith. And brewers and scientists are also looking beyond yeasts to bacteria in an effort to generate new varieties of beer known as “sour beers.” This is an area that is becoming more popular and a fertile ground for new beer types, says Smith. A number of researchers and brewers are working with Lactobacillus species to produce lactic acid in the fermentation process. This results in beers with a tart, sharp flavor.

Alongside the yeast cells themselves, brewers are looking to improved monitoring of fermentation in an effort to better control flavor. For example, a recent innovation involves acoustic-based sensors that measure changes in the density of the fermentation broth during the process. The sensors, developed by TZero Labs (State College, Pa.; www.tzerolabs.com), work like a sonogram, detecting changes in the speed at which sound waves travel through the liquid. Because these changes are tied to progress of fermentation (consumption of sugar and production of ethanol change the fluid density), the sensors can tell brewers about fermentation starting point, ending point and progress without the need for any manual measurements, explains Stephen Wells, co-founder of Tzero Labs. As part of a broader automation solution offered to microbreweries by partner BoxcarCentral, the sensors allow remote monitoring of fermentation processes. The retrofittable sensors fit into sanitary ports in fermentation tanks and can replace hydrometers. The sensors are also starting to be used to monitor the fermentation rate by detecting the formation of carbon dioxide bubbles in the tank. This, combined with its precise ability to measure temperature, allows brewers to investigate how small temperature adjustments can affect yeast activity and flavor.

 


 Beer Brewing Basics

Although hundreds of beer types exist, most are variations using only four basic ingredients: barley, water, hops and yeast. The process begins with barley (although other grains can be used to brew beer) the grains must be milled to crack open the grain husks, but brewers must modulate the milling so that the cracked husks are still intact enough to serve as a filter bed later. The milled barley, known as grist, enters a mash turn, where the milled barley is mixed with water and heated. In the heated water, enzymes from the milled grain convert starches in the grain into fermentable sugars. The mash stage creates a solution of sugars and water, known as wort, and spent grain, which must be separated by lautering, in which solids from the mash settle and form a filter bed over a perforated surface, through which the wort is collected. The wort is heated to halt enzyme activity and condense the liquid. At this stage, hops are added to flavor the beer and add the desired bitterness. Next, the wort enters a fermentation tank, where yeast is added. The yeast converts sugars in the wort to ethanol and releases carbon dioxide. Yeast also produces byproducts, which impart different flavors. The beer is then carbonated using high-pressure CO 2, and bottled (or canned).


 

Resource conservation

While beer taste and quality are rightly at the forefront of technology development, all brewers are also constantly trying to identify ways to lower energy consumption and resource use in the brewing process. Here, one of the largest companies in the brewing space, Anheuser Busch InBev (AB InBev; Leuven, Belgium; www.ab-inbev.com) has developed technology that allows the wort-boiling step to be carried out at below boiling temperature, reducing total energy use by 10% and lowering water use by 2–3%. Elevated temperature and bubble formation in the wort-boiling step are essential for some of the many chemical and physical transformations that occur there, according to David De Schutter, Innovation and Technology Development Director in Europe for AB InBev. “We carefully maintain the temperature at 1°C below the boiling point, which allows the temperature-dependent transformations to happen,” De Schutter explains, “and we introduce sparging gas [either N2 or CO2 ] using spray balls to mimic the bubbles you would see at boiling temperatures.” This achieves the objectives of the wort-boiling with lower energy use and less water evaporation. The process was developed at AB InBev’s Global Innovation and Technology Center (GITeC) and has now been implemented in several locations. AB InBev is validating the process for its other brands, De Schutter says. The lower-temperature process is part of a wider global sustainability effort by AB InBev to reduce carbon emissions across its supply chain by 25% by 2025. AB InBev is open to licensing agreements for the technology, and is offering free licenses to small brewers, De Schutter says.

In a more drastic shift in process approach, also aimed at energy and time savings, researchers Lorenzo Albanese and Francesco Meneguzzo, at the Institute of Biometeorology of the National Research Council (CNR; Florence, Italy; www.ibimet.cnr.it) have developed a controlled hydrodynamic cavitation technique in early process steps prior to the fermenting step. The cavitation is designed to replace the need for dry-milling the grain and boiling the wort in a traditional process. Known as Cavibeer Technology (www.cavibeer.com), the technique, jointly patented by CNR and the private company Bysea S.r.l., works by pumping the water-grain mixture through one or more specialized Venturi tubes, where the fluid accelerates and the hydraulic pressure drops due to Bernoulli’s principle (in fluid dynamics, an increase in fluid speed results in decreased pressure). The Venturi tubes are small (tenths of centimeters in length), and a careful design is crucial, the researchers say. The pressure drop through the tubes results in the formation of a large amount of micro- and nanoscale vapor-filled bubbles, which then implode when the pressure recovers downstream after a few milliseconds.

The implosion of the bubbles creates extreme releases of energy at the microscale, and it is this energy that can be harnessed for mechanical effects, such as breaking the solid grains, and for accelerating the release of sugars from the grain. Used early in the process, the cavitation renders unnecessary the dry milling of the grains, and raises the extraction of enzymes and starches from the malt. Also, saturated fatty acids are partly burned inside the collapsing bubbles, favoring foamability in the finished beer. When used later, after mashing-out and during hopping, cavitation increases the efficiency of extraction of the hops chemicals responsible for beer’s bitterness, as well as of valuable biocompounds capable of boosting the beer’s shelf life. Albanese and Meneguzzo say that the use of controlled cavitation can reduce the energy required for brewing by at least 40% and realize time savings of 60% or more. By tuning cavitation, even the gluten content can be reduced down to the gluten-free threshold without adding chemicals, the scientists say.

The two researchers have set up a pilot system (250 L) to test the cavitation process and have installed an industrial-grade cavitation brewing process (12 hectoliters), constructed by the partner company GBL S.r.l., at the San Gimignano Brewery in Barberino Val d’Elsa, Italy.

The Cavibeer team spent considerable effort in optimizing a mash filtration unit and taking steps to reduce the noise to the current insignificant levels. The industrial-grade plant is now fully reliable and scalable up to at least 200 hL. Currently, several beer recipes and styles are being tested and tasted at the San Gimignano Brewery.

Utilizing CO2 products

Brewing inescapably generates significant amounts of carbon dioxide as the product of fermentation. Since this gas is also needed for carbonation and gas purging in the beer process, it also presents opportunities to brewers.

“The CO2-reuse opportunity is huge for breweries,” both from an efficiency standpoint and an environmental one, says Ryan Reid, an independent engineering consultant with a portfolio of craft brewing clients. “However, right now, CO2 reclamation only makes economic sense for the largest brewers because collecting it, purifying it, pressurizing it and storing it is very capital-intensive.” But the costs are creeping steadily downward, Reid says, and it may become economically viable for smaller operations in the future.

One researcher who may help lower the cost of CO2 capture at breweries is Congwang Ye, a research and development engineer at the Lawrence Livermore National Laboratory (LLNL; Livermore, Calif.; www.llnl.gov). Ye has developed silicone microcapsules containing a solution of sodium carbonate (Figure 2) that adsorbs CO2 gas. Although the original conception targeted CO 2 capture from power-plant exhaust gas, the microcapsules could theoretically collect CO2 coming from fermentation tanks. The microcapsules release the gas at elevated temperatures, so the microcapsules could be reused. “Normally, Na2CO3 adsorbs CO2 slowly, so it’s not used as a capture vehicle, but encapsulating the Na2CO3 inside a silicone shell dramatically raises the contact area with the gas, so the capture efficiency goes way up,” Ye says. The microcapsules are made from a benign silicone that is safe for a food process. The LLNL team is also working on a new method for making uniform microcapsules at larger scale.

Figure 2. Silicone microcapsules of sodium carbonate could allow CO2 capture at lower costs LLNL

Figure 2. Silicone microcapsules of sodium carbonate could allow CO2 capture at lower costs
Photo: LLNL

For the brewing sector, Ye envisions onsite collection of CO2 and piping the gas to a geographically central hub facility near a network of breweries. There, it would be concentrated, purified and re-used by the breweries. A more compact modular unit that allows onsite reclamation is also in the plan to further reduce the cost. Because the microcapsule-based scheme is efficient and much less capital-intensive, it could be a solution for a wider swath of the brewing industry, Ye says.

Water management

Beer brewing requires large volumes of water, only 20% of which ends up in the final product. In the past, 6-7 gallons of water could be used for each gallon of beer produced, not including the water needed to grow the barley and hops. Through experience and effort, brewers have been able to trim this down to about 4:1 in recent years. Lower ratios of 3:1 or lower are possible with capital investment and good operating practice. Wastewater from the mashing step and other areas of the brewing process contains high levels of biological oxygen demand (BOD) and is often routed to municipal water plants. In many areas, brewers face caps and surcharges for high-BOD wastewater.

For all brewers, the local situation around the brewing site is critical, but onsite wastewater treatment can offer opportunities for water reuse at certain brewery sites, depending on the abundance or scarcity of low-cost water. For example, many brewers use anaerobic digesters onsite to treat their wastewater before it is routed to municipal wastewater treatment systems. The digesters can be used to generate biogas, which can be collected and used as fuel for boiling.

“Establishing key performance indicators (KPIs) for water is on the rise among brewers,” says brewery consultant Ryan Reid. But water re-use programs are often difficult to implement, especially for small brewers, because water is still inexpensive in many areas, so projects are sometimes difficult to justify economically.

The drivers are very regional, and include the price of water, price of wastewater treatment, the price of energy and more, says Michael Hribljan, VP of food and beverage for Suez Water Technologies and Solutions. “Water–reuse is garnering a lot of interest globally especially in water-scarce regions,” Hribljan says, but implementing water re-use solutions can be challenging, because breweries are so diverse in size and product portfolio, he explains, as well as having different local circumstances.”

“In many cases, breweries can look at taking process wastewater and recycling back into the brewery for boiler feed, cooling water, clean-in-place systems or bottle washing,” Hribljan says. “Technology currently exists to bring wastewater up to potable water standards with relatively few steps, including ultrafiltration, reverse osmosis, activated carbon and post disinfection.”

“Paybacks for investment in water treatment and re-use systems is often in the range of 2 to 8 years, depending on the cost energy, water and wastewater, both capital and lifecycle costs are very important,” Hribljan says. But choices both to implement, or not implement, water-reuse schemes also depend on customer perception and how brewers want to market their brands.

“CEOs recognize that water is strategically important for the long run,” he says and there’s an awareness that customers are more in tune with corporate sustainability. 

Scott Jenkins

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