ETHANOL PRODUCER MAGAZINE FEBRUARY 200698

Hopping Right Into Ethanol For some ethanol plants, controlling gram-positive

bacteria is a continuous battle. With resistance to

antibiotics on the rise—and distillers wet grains being

produced in greater quantities than ever—producers

are turning to alternative anti-contamination agents like

IsoStab, a natural hops-based product that thwarts

germs and allows yeast to dominate.

By Tom Bryan

FERMENTATION

Hop cones

ETHANOL PRODUCER MAGAZINE FEBRUARY 2006 99

ops, “the spice of beer,” havebeen used in brewing for over amillennium. This pinecone-look-

ing plant is known to impart bitterness,aroma and preservative properties, givingbeer its flavor and keeping the beveragefresh between production and consump-tion. For decades, scientists have graduallyunraveled the mysteries inside the hopcone. What they’ve discovered—and whatthey’re still figuring out—says WilliamPopa, may bring about small but importantchanges in the way ethanol is produced.

Popa, ethanol project manager forBetaTec Hop Products in North America,tells EPM that many of the active com-pounds found in hops—more specifically,the same organic acids that make beer bit-ter—are known to have antimicrobial qual-ities. “It’s why breweries don’t have biolog-ical outbreaks,” explains Popa, who helpedBetaTec introduce its flagship hop extractfor ethanol production, a liquid producttrademarked IsoStab, at the 2005International Fuel Ethanol Workshop &Expo in Kansas City, Mo.

Now, after a period of extensiveresearch and development, and a successfulintroduction of IsoStab in the U.S. market,BetaTec, a subsidiary of German-ownedBarth-Haas Group, is working closely withits global ethanol industry customers todevelop new and improved all-naturalethanol fermentation products. As Popa

explains, controlling the formation ofgram-positive bacteria is the name of thegame for BetaTec—and doing it with natu-ral products has big-time appeal for its newtarget customers.

Natural bacteria buster While most U.S. producers have

learned how to effectively control bacterialcontamination, it’s still one of the indus-try’s leading causes of ethanol yield reduc-tions. It’s also a big drain on product quali-ty. To be able to operate cost-effectively, it’svital to control bacteria in ethanol fermen-tation. For some producers, this is com-monly achieved by adding antibiotics as aprocessing aid during fermentation.

However, rising concerns about the role ofantibiotics for agricultural and technicalapplications—especially after the emer-gence of antibiotic-resistant bacteria—iscreating a strong demand for safe, naturalalternatives. “More and more ethanol pro-ducers are seeking to produce distillersgrains that can be labeled ‘antibiotic free,’”explains Lilith Ruckle, BetaTec’s Europeanethanol project manager. “In the EuropeanUnion, for example, if fermentationcoproducts are used as animal feed, theymust not contain residues of antibiotics.This law became effective at the end of2005. Other nations have implementedsimilar laws and some believe the UnitedStates could eventually follow suit.”

FERMENTATION

H

Hops grow on vines and are climate-sensative.

‘What we have foundis that by feeding justenough to control the

gram-positive bacteria,we can then set up abetter environment for

the yeast to growfaster, be more vitaland actually produce

alcohol faster.’

ETHANOL PRODUCER MAGAZINE FEBRUARY 2006100

In addition, Popa says more and moreU.S. ethanol producers are trying to getaway from drying distillers grains in orderto cut costs. “With wet cake, the fear is thatthe product still might have antibiotics init—particularly amoxicillin or virgini-amycin—which goes right into the cattlefeed,” Popa says. “Our product is an all-natural, kosher-certified, food-grade addi-tive. … It’s very safe.”

During the manufacturing of fuelethanol, bacteria contamination can occurin nearly every step of the process wherewater and starch are present at tempera-tures below 104 degrees Fahrenheit, Rucklesays. Since corn and other grain often pickup bacteria in the field, contamination gen-erally originates from the starch material.Washing the grain helps lower the bacteriacount, but bacteria contamination is essen-tially unavoidable. Ruckle says bacteria con-tamination is often found in yeast propaga-tors, steep tanks, fermentors and heatexchangers, where the temperature, pH andglucose levels are ideal for bacteria growth.“Bacteria can grow nearly 10 times fasterthan yeast, so contamination in these areasbecomes inevitable,” Ruckle explains.

To minimize bacteria contamination,most ethanol plants clean this equipmenton a regular basis and run their processes atlow pH levels. Many plants also try to per-form their steeping, mashing and fermenta-tion as quickly as possible to minimize lac-tic acid formation. Unfortunately, even lowlevels of bacteria reduce ethanol yield and,if severe enough, can slow or stop fermen-tation. Many batch ethanol plants useantibiotics daily to avoid bacteria problems;

others use antibiotics when bacteria prob-lems get severe. Continuous fermentationplants rarely use antibiotics, but they will ifbacteria contaminations are high. If noantibiotics are used, it is common for aplant to experience a 1 percent to 5 percentloss in yield. For example, a 50 MMgyethanol plant operating with a lactic acidlevel of 0.3 percent (weight-by-weight) is

losing approximately 570,000 gallons ofethanol annually due to bacteria, accordingto Ruckle.

If it works for making beer …Historically, six hops have been used in

brewing, and over the past 40 years, thehops industry has developed into a high-tech ingredients supplier to the world’s

FERMENTATION

Harvesting and processing hops is a labor-intensive process which workers in BetaTec’s Yakima, Wash., processing plant demonstrate above.

BetaTec Hops farm, manufacturing plant located in Washington’s unique Yakima Valley

BetaTec Hop Products was founded in Nuremberg, Germany, in 1997. The company is a sub-

sidiary of the privately held Barth-Haas Group, a company formed when U.S.-based John I. Haas Inc.

merged with German-based Barth. The company is the largest hops grower and hop products manu-

facturer in the world and bases its U.S. commercial operations in Yakima, Wash., located in the climac-

tically unique Yakima Valley.

Before merging with Barth, John I. Haas had been a supplier to the brewing industry for more than

100 years. The company’s Yakima operations include a hops farm and manufacturing campus that has

a cold storage facility, pelletizing plant, carbon dioxide extract plant and isomerization plant.

Carbon dioxide is used to extract hop acids. “This extract is a thick, sticky substance,” says William

Popa, senior vice president of new business development for BetaTec Hop Products in North America.

“It’s almost a molasses-like material.” The extract is isomerized, or broken down, into a very pure liquid

product that can be easily used in the brewing, beverage alcohol and ethanol industries.

The climate in the Yakima Valley is ideal for growing hops because it rains only about three months

out of the year there. “The rest of the time, it’s desert-dry,” Popa says. “Plus, the soil in the valley has a

lot of volcanic ash in it.” The Yakima Valley also gets approximately 16 hours of sunlight per day during

the peak growing season, giving the hops just what they need—a wet spring and a dry summer.

Hops will typically grow from March until they’re picked in late August. “They grow on vines like

grapes,” Popa says. “You actually have to train them and put them up on a string, so they grow up in

the air and off the ground. There’s quite a bit of labor involved.”

A large portion of the brewing industry still uses hops pellets in their cookers. “They’ll throw pellets

in their cookers for flavor, texture and foam characteristics,” Popa says. “Each variety of hops will give a

different characteristic to the beer, or in some cases, spirits. “If you’re making rye (whiskey) and you want

a little more tang in there, you throw a little hops in.” EP

ETHANOL PRODUCER MAGAZINE FEBRUARY 2006 101

leading beer makers. Hop companies likethe former John I. Haas Inc., essentially theU.S. half of Barth-Haas Group (see pulloutbox), have come up with better, more effec-tive hop extracts for brewing, identifyingalpha and beta resins in hop cones. Hops areextracted with carbon dioxide, and much ofthe resulting carbon dioxide extract is furtherprocessed to separate the alpha acid fractionfrom the remainder of the hop extract. Thealpha acids are then thermally isomerized intoisoalpha acids formulated to exact specifica-tions for ease of use and precise addition tobeer. “From there, we have been able to getspecific characteristics,” Popa says. “Thebrewers are getting so sophisticated now. Forexample, if they want a foam, we’ll add a spe-cific entity. What this has done is, instead ofusing large amounts of hops, they’re concen-trating on using lower amounts of hops tomake the same amounts of beer.”

That’s good news for brewers, but notfor growers and sellers of hops, Popaexplains. So about five years ago, John I. Haasstarted looking at other industries to sell itshops products to. “The ethanol industry was anatural fit because what brewers do to makebeer—or in the spirits industry, what they doto make rye-blend whisky—is basically whatethanol producers are doing,” Popa says. “Wejust had to be a little bit more creative in howwe applied the product.”

Of course, there are key differencesbetween beverage production and fuelethanol production, so to determine whichhop acids were the most effective at inhibitingthe growth of bacteria common to fuel

ethanol production, BetaTec tested all sixacids extensively. The hop acids tested werealpha acid, beta acid, isoalpha acids, rho-isoal-pha acids, tetrahydro-isoalpha acids and hexa-hydro-isoalpha acids. Lactobacillus brevis andLactobacillus fermentum were the two bacteriaBetaTec used for its testing and are the mostcommon contaminants in fuel ethanol pro-duction.

The testing results are extensive and toodetailed for the scope of this article, but whatBetaTec essentially discovered is that by intro-ducing minimum inhibitory concentrations ofthe right hop acids—the acids contained inIsoStab—into the ethanol productionprocess, gram-positive bacteria growth can bestopped, leading to increased ethanol yieldsand, in some cases, allowing ethanol plants toavoid the use of antibiotics altogether.“IsoStab is very good at controlling gram-positive bacteria,” Popa says. “Most of yourlactic acid bacteria is gram-positive. At the lev-els that we see our product in the plant, we’reusually not trying to get a total kill, or sterilizethe bacteria. We are just trying to feed enoughto control it. What we have found is that byfeeding just enough to control the gram-posi-tive bacteria, we can then set up a better envi-ronment for the yeast to grow faster, be morevital and actually produce alcohol faster. Wecontrol bacteria, so yeast can dominate.”

Producers pleased with resultsIn the past six months, BetaTec has had

good commercial success with IsoStab in theU.S. ethanol industry, Popa says. The compa-ny is coming out with customer proof state-ments detailing how the product has beeneffective for a number of plants. “We’re see-ing that where this product is working best isin corn mash that is resistant to virgini-amycin,” Popa says.

In fact, experts say new antibiotic-resist-ant bacteria are emerging, something Popaand others are experiencing first-hand. “A yearago, we didn’t know about the resistanceissue,” Popa says. “We’re just now collectingdata on it, and it has been very interesting. Justabout every mash sample I’ve pulled in the lastsix or seven months has a viginiamycin-, peni-cillin- or amoxicillin-resistant organism in it.”

Several U.S. ethanol producers are nowusing IsoStab daily and reportedly benefitingfrom it. “The producers we are working withare seeing an increase in alcohol productionwith less corn usage,” Popa says, adding thatproducers using IsoStab are also seeing fluctu-ations in ethanol yield tightening up.“Scientifically, we can’t say exactly why this ishappening, but we have done yeast vitality stud-ies, and it does seem that the yeast grow betterin the hops material than they do in mash byitself or in mash with antibiotics. For lack of abetter way to describe it, the yeast are simplyhappier.”

While IsoStab can replace the use ofantibiotics altogether, Popa says it is generallyused as part of a control regiment that mightinclude antibiotics. “We’ve seen good resultswith that, where the bacteria won’t adjust to anyone environment,” he says. “Every week or so,you change that environment so [bacteria] can’tadapt.”

Even though BetaTec’s introduction ofIsoStab is still relatively novel, the company iswasting no time developing its next line of all-natural fermentation products. “I think IsoStabis an excellent product—certainly a great firstproduct to have on the ethanol market—butwe’re going to develop several new productsand introduce them over the next 12 to 18months,” Popa says. “We’d like to have a cou-ple of all-natural products besides the hops-based materials that can be used in ethanolproduction.” EP

Tom Bryan is editorial director of EthanolProducer Magazine. Reach him at tbryan@

bbibiofuels.com or at (701) 746-8385.

FERMENTATION

‘For lack of a betterway to describe it,

the yeast are simply happier.’

BetaTec’s isomerization facility

This article was printed in the 2006 February

issue of Ethanol Producer Magazine.