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Reflections of a decaf avoider: this CO2 decaf is ok.

Reflections of a decaf avoider: this C[O.sub.2] decaf is OK

Let me tell you my preferences from the beginning ... every morning I drink a huge mug of strong coffee (made with a little over an ounce of coffee per mug) and then throughout the day I drink espresso. I've never had any desire to drink decaffeinated coffee, my attitude has always been that if caffeine is a problem, drink one cup of coffee a day and make sure that one cup is made from really good coffee. When you talk about good wine, you talk about quality and taste rather than amount, don't you? Well, the same principle has always applied to my personal philosophy about coffee.

Bearing in mind my prejudices, you can imagine how I felt when I had a cup of coffee at a coffeehouse some friends of my own, commented on how good it tasted, and was told that it was C[O.sub.2] decaffeinated coffee. I sputtered and stammered and was somewhat embarrassed since I've always made a big deal about decaffeinated coffee and its resemblance to warm brown water, but I drank the whole cup of C[O.sub.2] decaffeinated coffee and thoroughly enjoyed it.

Grant and Kathy Heath, owner/operators of the Kaffeeklatsch in Huntsville, Alabama, have extremely well-developed palates. They've introduced me to some of the best wines I've ever tasted, the best food I've ever eaten, and the best espresso I've ever sipped. They both drink decaffeinated coffees and are both impressed with C[O.sub.2] decaffeination. I was impressed because it was a "naturally" decaffeinated coffee that actually tasted like coffee. As a result, I took off my blinders and decided to find out more about this type of decaffeination and to share my information with you.

Water's Role in All Decaffeination

All decaffeinated coffees, regardless of the decaffeination method, have one thing in common, the process starts by wetting the bean. The bean can either be steamed, or soaked, or a combination of the two can be used, but water has to come in contact with it. After the bean is moistened, it can be decaffeinated in many different ways.

Gourmet coffee is usually decaffeinated by the "Swiss Water" Process, or the "natural water" method. In both methods, the green coffees beans are soaked in water. The beans swell, pores open and caffeine is converted to a mobile form that diffuses out of the bean into the water forming a caffeine laden water solution. Water is a natural solvent and, if beans are soaked in it long enough, it draws out the caffeine. Water is not a discriminating solvent though and with enough time, in addition to caffeine, it will draw out other flavor components that give coffee its unique taste.

"Swiss Water" Process

This method of decaffeination is so unique that the name and process is trademarked and consumers ask for it by name. The company that does the "Swiss Water" process is called Coffex and it has plants in Europe and North America.

In the "Swiss Water" method, the water solution containing the caffeine and flavor components is passed through carbon filters to remove the caffeine from the water. In the original process, still used in Europe, some of the water-soluble flavor components suspended in the water were removed with the caffeine. To replenish the lost flavor, the flavor-charged water was sprayed on the caffeine-free beans as they dried, returning some flavor to the beans.

In the mid-80's, the procedure was refined at the Coffex North America plant in Vancouver, B.C., and the flavor-charged, caffeine-free water was used to remove caffeine from subsequent batches of beans. After a batch of beans has been processed and the carbon filter removed the caffeine, the new generation of Swiss Water decaffeinated uses this flavor-charged water to decaffeinate subsequent batches of beans. The caffeine-free water absorbs the caffeine from the new beans, but the flavor components cannot pass into the already flavor-saturated water.

"Natural Water" Process

The name can be somewhat misleading since all decaffeination methods use water and it is not to be confused with the "Swiss Water" process.

In the "natural water" method, the water solution containing the caffeine and flavor elements is separated from the beans and treated with a solvent (methylene chloride or ethyl acetate). The solvent absorbs the caffeine from the solution and is then evaporated off. Because the solvent only touches the caffeine and flavor laden water solution and not the beans themselves, this method is also known as an "indirect" decaffeination method.

The water containing the coffee flavors is then rejoined with the coffee beans and the beans absorb their original flavor. Health-minded consumers sometimes shy away from coffee decaffeinated in this manner because they are concerned about the residual level of solvents in the water after the caffeine is removed.

I have personally found decaffeinated coffees that soak the beans in water to draw out the caffeine to have somewhat of a flat taste, that's why I have always preferred to limit the number of cups of coffee I drink per day rather than drinking decaf. (In all fairness though, I did try some "Swiss Water" decaf. processed at the Vancouver plant and it was much better than I remembered.) After trying this C[O.sub.2] decaffeinated coffee though, I may switch.


C[O.sub.2] decaffeination is not new, it has been around for a while. Because the start-up costs of a C[O.sub.2] decaffeination plant are quite high, this chemical-free method has been used primarily to decaffeinate large quantities of commercial grade coffees rather than smaller batches of gourmet coffees.

While I was researching it, I read through the August 1988 issue of this magazine and noticed that Dr. Samuel Lee had written a piece entitled "Supercritical Decaffeination" in his column Coffee Break. In it he discusses various decaffeination methods and has this to say about C[O.sub.2] decaffeination:

The ideal extractant (for caffeine) is carbon dioxide in the supercritical state. Carbon dioxide as a natural component of roasted coffee itself, as well as the air we breathe and exhale, meets all the requirements of an ideal solvent for decaffeination. It is highly selective for caffeine and creates no fire or toxicity hazard. It is chemically stable and inert to coffee constituents, non-corrosive, easily removed from the green beans and the extracted caffeine, immaterial if a small residue remains, and is inexpensive.

....Supercritical C[O.sub.2] extracts practically none of the coffee or tea aroma precursors. After roasting, aroma and flavor are essentially indistinguishable from the unextracted beans.

Bernard Rothfos, in his book Coffee Consumption, published in 1986, gives a good definition of supercritical (or as he calls it, hypercritical) in the section of the book entitled "Decaffeination Through Extraction by Means of Hypercritical Gases."

This method is based on the discovery that gases, when in a hypercritical state, show properties similar to those of solvents. The green coffee previously subjected to a steaming process, is treated in a pressure vessel at an increased temperature and pressure level with a hypercritical gas, for instance with carbon dioxide (C[O.sub.2]) which thereby absorbs the caffeine.

This "hypercritical" (supercritical) state is a specific state of compressed gases (in this case of the carbon dioxide) which exists alongside other states such as "solid," "liquid," or "gaseous." The carbon dioxide which at a normal temperature is in a gaseous state will at a certain characteristic ("critical") temperature transform into something like a thick steam, called the "hypercritical" (supercritical) state. It resembles a liquid, but has the mobility of a gas...Hypercritical (supercritical) carbon dioxide dissolves nothing but the caffeine from the green coffee using a kind of extractive distillation - however only if the coffee beans contain enough water to act as a means of separating, dissolving, and transporting the caffeine.

The C[O.sub.2] method of decaffeination is totally natural, the process only requires green coffee beans, water, and carbon dioxide. Carbon dioxide is an extremely selective solvent, it does not touch the carbohydrates (sugars and starch) and peptides (protein) which, during roasting, are converted to the compounds responsible for the flavor and aroma of brewed coffee.

I stated in the beginning that, as a rule, I don't like decaffeinated coffee. But rules are made to be broken, and I'm here to tell you that, in my opinion, this C[O.sub.2] decaf is OK and I think that when C[O.sub.2] decaffeinated gourmet coffee becomes more readily available to the consumer, they'll think so too.

In the early to mid-80's, the consuming public was becoming more aware of gourmet coffee while at the same time becoming increasingly aware of health concerns. Along with the concerns about caffeine were concerns about the decaffeination method. Consumers were told that coffee decaffeinated by applying chemical solvents were bad for you because of the residual solvents in the beans. If you wanted to be really selective, you'd drink only "water" or "naturally" decaffeinated coffee. In the rush to get these upscale, more expensive, but "healthier" decaffeinated coffees to the consumer, something was lost in the process -- taste.

I have a theory that many consumers tried the new decaffeinated coffees, found them lacking in taste and went back to their old coffee habits, just limiting the number of cups per day. According to the August 1990 study of the Gourmet Coffee Market conducted by Find/SVP, the share of all coffee drinkers drinking decaffeinated coffee was 17.3% in 1985, 17.1% in 1986, 17.5% in 1987, 15.8% in 1988, and 16.7% in 1989. With the forward momentum of sales growth and the emergence of new decaffeination methods like the carbon dioxide method, there's no reason that the share of all coffee drinkers drinking decaffeinated coffee can't go to 17% or more in 1990.

Sales of decaffeinated coffee will never equal the sales of non-decaffeinated coffee, but it can get a healthy chunk of the market. Competition for sales of decaffeinated beans can only increase, so the different methods of decaffeination will become more important. Consumers are already becoming more selective about the brands or types of decaffeinated coffee they buy and will be more demanding that their decaf is just missing caffeine and not flavor ... and you know what I have to say about this, "It's about time."

If you or your customers have been experiencing bad tasting decaf coffee, give the new C[O.sub.2] process decaf coffee a try. It's not perfect, but it's pretty darn close.

In his article "Supercritical Decaffeination," Dr. Lee mentions that, several years ago, a major suppliers of carbon dioxide, Air Products and Chemicals, established a supercritical processing venture to assist in evaluating, developing, and commercializing extraction processes for various industries. This division was acquired by Supercritical Processing, Inc. in Allentown, Pennsylvania.

Supercritical Processing, Inc. (SCP) has developed a proprietary coffee decaffeination process using supercritical carbon dioxide as the extractive solvent. Since I am not shy, I picked up the phone, introduced myself, and spoke to Zvi H. Weinman who is president of the company. We had the following conversation. Interview on August 13, 1990, with Zvi H. Weinman, president, Supercritical Processing, Inc., 966 Postal Road, Allentown, PA 18103:

Sturdivant: From what I've read, the C[O.sub.2] decaffeination method is not something new, it was developed in Europe, brought over here in the 70's, and, since then, has undergone refinement. Can you tell me more about it?

Weinman: The company that was the first to bring it to commercialization was a German company, Cafe HAG. Cafe Hag was subsequently acquired by the General Foods Corporation and by virtue of that acquisition, the technology came over (to the United States). GF (General Foods) got into the technology through their HAG acquisition and then they did more work on it and they now have what we understand to have--the same supercritical C[O.sub.2] decaffeination but a different process from what HAG practices in Germany. This may be in the way they handle the beans or the temperatures or pressures, but they've set up their own plant in Houston which now does the decaf for Sanka and maybe other General Foods Brands as well.

Sturdivant: Are there different C[O.sub.2] processes? When someone says water process decaffeinated coffee, I want to ask which one, does the same thing apply to the C[O.sub.2] method?

Weinman: Yes. As far as we know, there are two basic ways that the technology can be used. What it goes back to is that carbon dioxide, under high pressures and moderate temperatures, has a good affinity for caffeine. (The pressure and temperature can vary according to the decaffeination plant.) Carbon dioxide dissolves caffeine in a wet coffee bean fairly selectively. It won't pull out a lot of other things.

Sturdivant: It does it quickly too, doesn't it?

Weinman: It does it quicker than, say, methylene chloride but your extraction time will be something on the order of five to eight hours.

Sturdivant: It's my understanding that, with water decaffeination, the beans are soaked in water and the water acts as a solvent and leaches out the caffeine. Unfortunately, water is not selective so it can leach out some of the coffees' desirable characteristics also.

Weinman: That is correct. In all decaffeination methods that I know of, you have to use water to decaffeinate beans. You can't decaffeinate dry beans. C[O.sub.2] will not dissolve the caffeine out of dry beans, you have to wet the beans. You have to steam the beans, or soak them, or some combination of the two.

Sturdivant: With your process, do you steam the beans or soak them?

Weinman: We do a little bit of both. We moisten the beans and our method employs the direct contact of the moistened beans with the supercritical carbon dioxide.

Sturdivant: But how is it done?

Weinman: It's two steps actually. The first step would be to set the beans by soaking and steaming them. Then they would go into a vessel, the vessel would be sealed, and then the beans would be contacted with supercritical C[O.sub.2] . This C[O.sub.2] would strip the caffeine from the moist beans. The beans are puffed up and full of moisture, but they are not soaking in water.

Sturdivant: When I've read about decaffeination, I've seen it explained that steaming green coffee beans brings the caffeine closer to the surface of the bean: soaking coffee beans in hot water causes their pores to open, the inside fibers to be fully saturated with water, and creates a better situation for water to leach out caffeine.

Weinman: We think two things are happening, we think that caffeine may be bound up in the bean as a salt, and we think the water would also disassociate the salt to allow the caffeine to then be trapped by the C[O.sub.2].

Sturdivant: When C[O.sub.2] comes in contact with the beans, how does the decaffeination process work? I've read that supercritical C[O.sub.2] exists in a state somewhere in between a gas and a liquid.

Weinman: Think of the supercritical fluid as a heavy gas, it fills up a container like a gas would but it's heavy. When it's heavy it can dissolve things. But what actually happens to the caffeine is exactly the same as what happens when you decaffeinate coffee with hot water, the caffeine dissolves into the water just the way sugar would dissolve in hot water, only, with the C[O.sub.2] method, instead of dissolving into water, the caffeine dissolves into the high density carbon dioxide. There is no chemical change, it is physical.

Sturdivant: Is there a particular temperature that the supercritical carbon dioxide nees to be at to dissolve the caffeine but not affect the favorable characteristics of coffee, like the flavor?

Weinman: No decaffeination method just gets the caffeine, everything is going to get the caffeine and something else. What you do is choose temperatures and pressures such that you minimize pulling anything else out and try to maximize on the caffeine.

Sturdivant: What does your method pull out besides the caffeine and won't it have a final effect on the taste of the coffee?

Weinman: In a good Arabica bean, the caffeine would make up a little over 1% of the bean, most extraction processes would extract between 3 and 5%, so you're going to extract 2-4% of something else. We extract between 2 and 4% right now and we're looking to reduce that but that's what we get now.

Sturdivant: What about the appearance and moisture content of the bean? Brother's chief complaint about water process decaffeinated coffee is the bean was so brown when it was "green", and so full of moisture, that it was really hard to call his roast.

Weinman: Our decaffeination process leaves the bean much lighter than the methylene chloride or "Swiss Water" process, but slightly darker than a green bean.

Sturdivant: Does it require any special techniques to roast?

Weinman: You don't want to let it go too far, it comes up to color a little quicker than a non-decaffeinated bean.

Sturdivant: Is that because the moisture level is lower than before it was decaffeinated or because of some of the unknown properties lost during decaffeination?

Weinman: It may be what's gone, we don't know, the moisture content is controllable. If the beans come in and before soaking the moisture level is 11%, after our decaffeination step, you put the beans in a dryer and dry them to 11% or lower. You can return the moisture level to what it was before the beans were decaffeinated.

Sturvidant: Do you measure the moisture content of the beans before decaffeination? And can you return them to the same level?

Weinman: We do. That's the second step. We measure moisture content on a routine basis before we decaffeinate because we have to bring the moisture content up to a specific standard before the process

Weinman: That's the second step. We measure moisture content on a routine basis before we decaffeinate because we have to bring the moisture content up to a specific standard before the process begins. The beans have to contain a certain amount of water before the C[O.sub.2] decaffeination process will work. We have to know how much water and steam to hit the beans with. After the beans are decaffeinated, we have to know what moisture level to return them to.

Sturdivant: Is this the type of thing that can set the different C[O.sub.2] processors apart? Is there a difference between what you do and what someone else does?

Weinman: There would be a couple of differences: One would be the conditions used. Slight differences in temperature and pressure can affect the taste. The second would be the type of C[O.sub.2] decaffeination method used. As far as we know there are two types: direct and indirect. We use a direct decaffeination method, so does General Foods. It is called direct decaffeination because the C[O.sub.2] comes in direct contact with the beans. The beans are directly decaffeinated with supercritical C[O.sub.2]. Another C[O.sub.2] method which, as far as we know of, has not been commercialized is an indirect one, similar to the "Swiss Water" method where the beans have been soaked in water and then the caffeine goes into the water solution and then the water solution is hit with the supercritical C[O.sub.2]. The method is called indirect because the C[O.sub.2] comes in contact with the water, not directly with the beans. As far as we know, the indirect method has never been commercialized while the direct method has.

Sturdivant: Why do you think the indirect hasn't?

Weinman: It is a relatively new process, it was recently developed by a major roaster who developed it for its own products, and is not interested in carrying it any further.

Sturdivant: The C[O.sub.2] process has been in the U.S. for a number of years, and it would seem to be a natural for gourmet coffees since it extracts the caffeine but leaves the different taste characteristics. Is it readily available here in the U.S.?

Weinman: Right now, the plant start-up cost is relatively high and, if you want to sell a C[O.sub.2] decaffeinated bean, there is no place in the U.S. you can go to have it done.

Sturdivant: Does your company do the supercritical C[O.sub.2] process?

Weinman: Only on a small scale, we don't have the production capacity to do anything large scale. We have perfected our process and now we are looking for coffee companies that would be interested in licensing our process or working with us so we can get a plant up and running in the U.S.

Sturvidant: Why do you think supercritical C[O.sub.2] decaffeination process is now generating interest?

Weinman: I think that more and more people are concerned about their health and if they can do without the caffeine they had just as soon do that. But at the same time they are also concerned about what is in the product, how the coffee is decaffeinated, and residual traces of solvents that are potentially carcinogenic.

There is also a taste concern, and there is a taste difference between coffees decaffeinated by different methods.

The C[O.sub.2] method provides a good coffee flavor and a safe extraction process.

Sturdivant: So you think the C[O.sup.2] is the up and coming decaffeination method?

Weinman: I do. We've spent a lot of money and effort developing our process. The big stumbling block for the commercialization of the technology is the start-up cost for the plant. It's high pressure process and the equipment is expensive. But once you overcome the initial capital hurdle, the operating costs are very low.

Sturdivant: How would you describe yourself and your company, supercritical decaffeination, Inc.?

Weinman: We are dedicated to the commercialization of this technology in coffee and in other food and non-food applications as well. We've developed our own decaffeination process and are looking to find coffee companies that would be interested either individually or with others to support the construction of a decaffeination plant based on our process.
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Author:Sturdivant, Shea
Publication:Tea & Coffee Trade Journal
Article Type:column
Date:Sep 1, 1990
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