martes, 1 de marzo de 2011

BEER CHEMISTRY

Are brown bottles better for beer?


Beer is typically made from water, malted grains, yeast and hops, which combined to produce more than 600 volatile compounds. These chemical reactions continue to occur as the beer ages. And as with most chemical reactions, they are affected by energy in the forms of both heat and light. Some of these reactions can yield a mellower flavor. Too much light, however, can be a problem and leads to ‘lightstruck’ or ‘skunky’ beer.

The substances that are most affected by light are found in hops. Hops are the cone like flowers of the climbing plant Humulus lupulus and are used to give beer its bitter flavor and many unique aromas. When light reacts with certain hop-derived compounds, it creates a variety of unpleasant-smelling and -tasting chemicals, with 3-methyl-2-butene-1-thiol (MBT) being the major offender.

Light-resistant hop extracts are now available that can help prevent beer from becoming lightstruck. Antioxidants can also be used. But these approaches affect the final taste of the beer. The best solution is to keep the beer from being exposed to light. And that is achieved through the packaging. Cans are optimal, but for glass bottles, brown glass blocks out more light than green glass, and both are far better than clear glass. Dark beers, which absorb more light, are best bottled in brown glass, while green glass is generally fine for lighter beers.

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GREEN CHEMICALS

The Green Seal certification is granted by the organization with that name and has a great number of members contributing with the requirements to pass a raw material or a chemical product as "green". Generally for a material to be green, has to comply with a series of characteristics like: near neutral pH, low volatility, non combustible, non toxic to aquatic life, be biodegradable as measured by oxygen demand in accordance with the OECD definition.
Also the materials have to meet with toxicity and health requirements regarding inhalation, dermal and eye contact. There is also a specific list of materials that are prohibited or restricted from formulations, like ozone-depleting compounds and alkylphenol ethoxylates amongst others. Please go to http://www.greenseal.com/ for complete information on their requirements.
For information on current issues regarding green chemicals, see the blog from the Journalist Doris De Guzman, in the ICIS at: http://www.icis.com/blogs/green-chemicals/.
Certification is an important — and confusing — aspect of green cleaning. Third-party certification is available for products that meet standards set by Green Seal, EcoLogo, Energy Star, the Carpet & Rug Institute and others.
Manufacturers can also hire independent labs to determine whether a product is environmentally preferable and then place the manufacturer’s own eco-logo on the product; this is called self-certification. Finally, some manufacturers label a product with words like “sustainable,” “green,” or “earth friendly” without any third-party verification.
“The fact that there is not a single authoritative standard to go by adds to the confusion,” says Steven L. Mack M.Ed., director of buildings and grounds service for Ohio University, Athens, Ohio.
In www.happi.com of June 2008 edition, there is a report of Natural formulating markets that also emphasises the fact that registration of "green formulas" is very confused at present, due to lack of direction and unification of criteria and that some governmental instittion (in my opinion the EPA) should take part in this very important issue.