The advantages of enzyme processing.
Enzymes are among the oldest and newest agents used in food as well as tea and coffee processing; and with the new advances in biotechnology, promise to become even more important in the future.
A recent report from a leading international manufacturer, Novo Nordisk of Denmark, disclosed that they are currently marketing three enzymes for the coffee industry--two for separation of the green bean from the cherry in washed coffee, and one for viscosity reduction of the liquid extract in the manufacture of soluble coffee. In the case of tea, although still prepared using the natural enzymes present in the leaf, black tea would be impossible without the action of these agents on the natural components of the green.
Natural enzymes have been used for centuries, without man knowing what they were, in such important and necessary products as leavened bread, beer, wine, vinegar, cheese, and many other commodities. Now with commercially manufactured and standardized enzymes, these processes are becoming even more satisfactory.
On the human side, most changes in physical status occur as a result of enzyme activity. Growth, digestion, nutrition, respiration, even many diseases and their alleviation would be impossible without these agents. In fact, all animal, vegetable, nautical and aeronautical life would be hopeless without their function, which subsequently converts remains of life to its elements.
During the last two decades the industrial use of manufactured enzymes has rapidly expanded. There is still great scope for growth. New types are opening up many new possibilities. In the beverage industries the use of enzymes may still be in its infancy and await imaginative development. Advantage of enzyme processes can be summed up in four words: efficiency, precision, convenience and cost effectiveness.
Structurally, enzymes are proteins, and like other proteins consist of long chains of amino acids held together by peptide bonds. They are present in all living cells, where they perform the vital process of controlling metabolic processes, whereby nutrients are converted into energy and fresh cell material. They also participate in the breakdown of foods into simpler compounds.
Well known enzymes include pepsin which decomposes proteins into simple amino acids; amylase which breaks down starch into simple soluble sugars; and pectase which converts adhesive pectin in the coffee cherry into soluble, easily washed out compounds.
Enzymes are capable of performing their function because unlike most food proteins such as egg albumin, gelatin or soy protein, they are powerful catalysts. By their presence and without being consumed in the process, enzymes can speed up the chemical processes that would otherwise run very slowly, if at all. After the reaction is finished, the enzyme is released again, to start another reaction. In principle this could go on forever, but in practice, after a while they get tired and have a limited lifetime. Sooner or later their activity becomes so slow that it is no longer practical to use them. Accordingly, most industrial enzymes are used only once and discarded after they have done their job. But such a small amount is required each time, that this does not become a commercial burden. For example, it is estimated that a teaspoonful of enzyme is sufficient to convert a ton of green tea to black. And it has been demonstrated that one enzyme molecule from the human liver can catalyze the breakdown of five million molecules of hydrogen peroxide in one minute.
In contrast to inorganic catalysts like those used in automobiles which can convert hundreds of different organic compounds to harmless exhaust, enzymes are very specific. Each can break down or synthezise only one particular compound. In some cases, they limit their action to a specific bond in the compound with which they react. Some proteases, for example, can affect several types of protein, but each protein molecule will be cleaved at the same specific bond. Thus in industrial processes, the specific action of enzymes produce high yields with a minimum of unwanted by-product.
Another great advantage of enzyme processing is that they work in mild conditions. Being designed to work in living cells, they perform their function at atmospheric pressure and in a gentle environment with respect to temperature and acidity. Most enzymes operate optimally at a temperature between 30 [degrees] and 70 [degrees] C., and in the neutrality range. For certain applications, special compounds have been developed that work at higher temperatures. However, no enzyme can withstand boiling water temperature or above, too long.
Enzyme processes are accordingly energy saving and very economical in equipment costs requiring no pressure vessels or expensive fabrication elements resistant to heat or corrosion. Also, high biodegradability minimizes pollution and disposal problems.
"Washed" coffees still command a premium over green prepared by natural removal of extraneous matter. Some coffee buyers with acute taste sensitivity feel they can differentiate between enzyme washed and alkali washed, and make their offering on this basis. The more efficient enzymes now available for this purpose have practically erased any cost of production differential.
In the case of the enzyme used in instant manufacture, there is a definite economic advantage, particularly for the freeze dried. When roasted coffee is extracted, if the liquid extract comes out of the percolators at 25% solids, this means that three pounds of water must be removed at one pound of product. If the liquid extract is evaporated to 50% solids, one pound of product requires the removal of only one pound of water. In freeze drying, water removal from the ice is far more expensive, and ordinary evaporation is well justified.
When the solids concentration of the liquor is increased, the viscosity also increases disproportionately due to the colloidal carbohydrates present. At the higher concentrations, the liquor actually gels and cannot be pumped or transferred mechanically to the freeze drier. By using the appropriate enzyme, the colloids are converted to a soluble state and the extract remains fluid enough to flow to the drier.
Future development in instant coffee manufacture lies in the realm of enzyme extraction of the coffee solids right from the beginning. Presently high temperatures and pressures are required to obtain complete and efficient extract of the solids. This requires the use of heavy steel vessels, piping and pumps, as well as substantial energy expenses. Once an enzyme system is developed, which even now is technically feasible, extraction costs will be diminished materially. Quality may even be improved through gentler treatment of the roasted coffee.
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|Title Annotation:||use of enzymes in coffee processing|
|Publication:||Tea & Coffee Trade Journal|
|Date:||Apr 1, 1991|
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