Harish Palaniappan's

You require:

*WATER
- 4 to 12 volumes of water, for one volume of beer.
*MALT
- Arguably the most important raw material...for those enzymes and extracts for making beer naturally.

Enzymes are catalysts of chemical reactions. Yes beer is made by a natural process similar to how curd/yoghurt is made from milk.

Malt is derived from special varieties of barley by the malting process.

*HOPS
- Kiln-dried cones also for extracts. Hops is a farm product like barley.

*YEAST
- A living organism (that is sold in packets in stores), and hence not called a raw material much of the time :0) Used for fermentation process which is largely responsible for making natural beer.

And yes, many other ingredients to create the flavor, the proper concentration of ingredients, and to make the proper popular flavored beer.

We have completed listing the core raw materials. The process is just a mixture of heating, fermentation, and extraction processes...better explained with scientific terms and details in 'related links' at the end of this article.

I will just avoid writing the chemical part and write here the part of beer technology that I liked understanding.

Enzymes in beer?
There are enzymes available for every chemical reaction of life...only for chemical reactions, not for anything else of life though :o). Enzymes are protein molecules which accelerate chemical reactions.

Carbohydrates in beer?
Carbohydrates are an important source of energy for living organisms and a means by which energy may be stored. The starch of barley, the malt and extracts provide for carbohydrates in beer. So, if anybody told that drinking beer is actually healthy, they are partially right, but then, there are much better foods to good health than drinking this fermented liquid (unless you drink beer not just for health). Beer is not drunk for its energy even if anyone told you so.

Carbon di-oxide in beer?
Carbon di-oxide is something that our body and most living beings exhale as impurity. And our vehicles do the same, as a pollutant.

But in beer carbon dioxide is used as a conditioner; and for that pressurized packaging in tins/bottles.

Oxygen in beer?
Some relief here from the above paragraph.. Oxygen is injected into the beer making process for allowing for yeast growth, for better fermentation.

Beer is green. not yellow?
Beer made naturally is Green beer, and the yellowish version is due to additives, coloring/flavoring agents, packaging agents etc.,

Well.. that's how much I found out about Beer !!

Related reading: If you are more interested in the manufacture process of beer that I left incomplete above... read one of these.

Book: "Brewing -by Lewis & Young"
Web links:
Making low-cost home-made beer.. with illustrations
How stuff works: Beer: Illustrations from factory