Additives. Brewing is a very traditional and natural process that does not generally call for the use of the sorts of additives found in many other modern foods. Most beers from most breweries are essentially additive-free; the natural raw materials and the biological processes involved in brewing are perfectly capable of producing excellent, tasty, healthy, and stable beer entirely without assistance from the additive industries.
Nonetheless, modern chemistry does sometimes find its way into the brewhouse. Additives used in brewing are categorized according to their purpose of use. Here we do not address the large group of so-called technical aids like salts and acids for water adjustments, enzymes, finings, and chemical stabilizers (insoluble chemicals that are not found in the finished beer) used for ensuring lasting clarity of filtered beers, etc. Nor do we address “alternative raw materials” like adjuncts, unmodified hop extracts, natural fruits, or herbs and spices. These are covered elsewhere.
In all markets the use of additives is regulated by the national and local food safety authorities. Regulations often take the form of a “positive list” detailing all additives allowed for brewing in that market and how they must be declared on the packages. For example, the EU positive list specifies the E-numbers that should be used in the ingredient declarations on the labels or cans. Regulations may also take the form of specific legislation prohibiting certain—or all—additives in beer.
This group of additives covers a wide range of different commercial products (e. g., rho-, tetra-, and hexa-iso-alfa-acid-extract), all being produced by various chemical modifications (reduction processes) of CO2 hop extracts. When used, primarily for industrial lager beer, these are added to finished beer just before packaging and offer the brewer several advantages: avoidance of skunky (lightstruck) flavors that might otherwise form in non-protective clear or emerald glass bottle (
By far the most commonly used agents for enhancement of chemical stability are the technical aids belonging to the silica group and the PVPP/ nylon group, covered elsewhere in this book.
One of these products is PVP (polyvinylpyrrolidone), a beer soluble substance which is a type of “plastic precursor” that is inert to virtually anything but polyphenols, to which it has a high affinity. When added to a beer, the PVP will immediately react with the polyphenols in the beer forming insoluble PVP/polyphenol precipitation that can then subsequently be filtered out of the beer. If not precipitated and removed, the polyphenols will eventually, under stress by time and/or temperature, react with some of the soluble proteins in the beer and form colloidal and eventually insoluble complexes causing a visual haze in the beer.
Another chemical stabilizer, nowadays rarely used in brewing, is the enzyme papain (the name stems from the Papaya fruit where this enzyme is abundant and from which it can be isolated), but sold under the commercial name Collupulin. When added to filtered beer, this proteolytic enzyme will degrade the proteins in the beer, including those that would eventually react with the polyphenols to form haze. Adding enzymes that are still active when the beer is consumed is prohibited in many countries, and regardless of legal implications, Collupulin—although very effective as a chemical stabilizer—also degrades foam-active proteins in the beer, thus reducing the head retention of the beer. As a result of both of these deficiencies it has fallen out of use in developed countries.
The chemical agents used for improvements of flavor stability are probably the most widely used additives in brewing. Especially for standard mass-market lager beers, they can be very effective with respect to improving the shelf life of these beers.
The most commonly used type of antioxidants in beer are sulphites. These very effective compounds all contain free sulphite that not only reacts with free oxygen but also with a large number of those “oxidation precursors” (aldehydes, most importantly) that would eventually be further oxidized into staling compounds. Sulphites are also naturally occurring in beer as they are produced as metabolites by the yeast, but the level varies significantly with both yeast strain and brewing process. This makes control of sulphite levels difficult for brewers who add sulphites to beer, especially in regards to markets where there are legal limits for total sulphite in beverages. Most countries regulate the level of sulphites in beer as they are well known to be allergenic. The majority of wine on the market also contains added sulfites.
Another important antioxidant used for beer is ascorbic acid (Vitamin C). The way ascorbic acid works to prevent or delay staling and oxidation is similar to that of the sulfites, but it is not as effective. Also, ascorbic acid may even under certain (but not well understood) circumstances act in the opposite way, namely as an oxidizer. Ascorbic acid is allowed in beer in most markets.
As is common in wine and liquor, the color of beer may be adjusted upward (toward higher color) by the use of a number of compounds. The most important is caramel color.
There are two normal reasons a brewer may use coloring agents in beer. The first is as a color corrective, used in small dosages as a final correction of the color of a wide range of beers. But it may also be used as part of the actual construction of a beer. As coloring agents are—at normally used concentrations—virtually without aroma or flavor, they can be used for producing dark beers with much less roasted aroma, flavor, and taste than would result from using dark malts to achieve the same color. An industrial brewer may thereby use a form of food coloring to give a beer the appearance of rich flavors where none may actually exist.
A wide range of different compounds may be used at all stages of production (including just before packaging, allowing brewers to produce a number of different “products” from the same “base beer”) so descriptions here cannot be comprehensive. Acids—the most common is lactic acid—may be added to give desired tartness, sugars added to increase body and mouthfeel, and various natural or artificial extracts or essences of fruits and herbs added to give non-beer related aroma, taste, and flavor. A good example of these is the recent fad of adding lime flavorings to mass-market lagers.
The use of foam stabilizers in brewing is obviously associated with situations where the head (
The only widely used foam stabilizer is called PGA (propylene-glycol-alginate), which is sold under a range of commercial names. This compound is an extract from certain types of seaweed that is subsequently chemically modified. PGA, whether purchased in powder or pre-dissolved form, is slurred in deaerated water, yielding a very viscous solution that is then mixed into the beer. The PGA acts by means of its extremely high surface tension that it lends to the beer, thereby creating much more durable foam bubbles when the beer is poured. This ersatz foam tends to have substantially different aesthetic qualities than natural foam, a fact that the consumer may or may not notice.