The concept of surface are to volume ratio has an important bearing on many things, coffee and tea included. In this article I'll discuss what surface to volume ratio (SA/V) is, and for the next article, why it concerns coffee and tea. To understand SA/V we need to understand the components that make it up - area (more specifically surface area), and volume. Volume is simply how much space an object take up in a 3D world. The volume of a cube would be its length times its width times its height (since in the case of cube, the length, width, and height are equal, the volume can be represented as l³) The volume of an object can also be found by measuring the volume of water the object displaces when submerged. Again, volume is a 3D measurement and is commonly measured in Liters, gallons, fluid ounces, etc. Regardless of whether I fill a basketball with air or lead it would have the same volume.

   Now on to area. Area is a 2D measurement of the space enclosed by a certain set of boundaries. The area of a square would be its length times its width (since in the case of square, the length and width are equal, the area can be represented as l²). Area is often measured in square meters, square feet, etc. Surface area is just the area of an object that is exposed to the environment; so it is still a 2D measurement, but it can be applied to 3D objects, like the surface area of a ball is 4?r² - while the volume of the ball is (4/3)?r³. The surface are to volume ratio of an object is just the surface area of the object divided by the volume of the object. So when calculating SA/V one is finding how much surface area the object has per the amount of volume the object takes up. So the higher the ratio, the more SA the object has per unit volume, thus the more direct contact the object has with its environment and will therefore react with the environment more rapidly. For example, a ping-pong ball would have a higher SA/V than a beach ball. Also, if I had a sheet of paper with the same volume as the ping-pong ball (which would be a huge piece of paper), the paper would have a higher SA/V. These can be inferred conceptually, or mathematically, depending on your preference.

   Conceptually one can just think about which object has more SA per unit volume, and thus which one would react quicker with its environment. Mathematically, in the case of the ping pong and beach ball, you can see from the above equations that as the size of the ball increases (increasing radius) the SA will increase by the square of the radius while the volume will increase by the cube or the radius, therefore the volume will increase quicker because it is increasing at a cubic rate as opposed to the square rate of the SA. SA/V ratios and their effects are not easy concepts to fully grasp. Hopefully after reading this article and ruminating on it a bit you will have an understanding of the concept, and for next Mugg's Buzz I'll write about what all this stuff has to do with coffee and tea!

  In the last article I explained what a surface area to volume ratio is. For this article I'll write about why it concerns coffee and tea. Remember, that the smaller SA/V an object has the more rapidly the object will react with its environment. Perhaps the most important reaction that coffee and tea undergoes is brewing! Because a an increasing SA/V, the finer coffee is ground, the more rapidly it will brew. As a very generalized rule of thumb, the compounds in coffee and tea extract in such a way so that the good stuff comes out first and the more unpleasant tasting compounds come out later (thus overextraction of coffee or tea is something that needs to be avoided (underextractoin is also to be avoided)). This is why when coffee is ground coarsely (such as for a French press), the grounds and water need to be in contact for 3-6 minutes for optimum extraction, and when it is ground very fine (such as for espresso), the grounds and water need to be in contact for just about a second for optimum extraction. So the lower the SA/V of the coffee grounds, the longer one needs to make the brewing time to achieve optimum extraction.

   The same issues being true for tea - tea dust and fannings extract very quickly, thus pretty much always overextract, so to get a cup of tea that is not overextracted one needs to turn to broken or whole leaf grade tea (loose tea). So that the extraction happens slow enough that the tea may be removed before the extraction progresses to far. SA/V is also the reason coffee should be stored as whole beans as opposed to grounds. Coffee goes stale through the process of oxidation and the higher SA/V the coffee has, the quicker it will go stale. This is why whole coffee beans will be good for about ten days, but if they are ground to a fineness used for espresso, they will be good for less than a minute.

   Since we have an art show this Friday at 8pm I thought I would write about the coffee - art relationship. The coffee - art relationship stems from and is part of the larger coffee - intellectual innovation relationship. When coffee was introduced to Europe from the Turks and displaced a lot of beer from European consumption. Coffee and coffeehouses then played a large role in the scientific revolution and Enlightenment in the 17th and 18th centuries (perhaps due to drinking coffee or perhaps because Europeans weren't drinking as much beer with breakfast). The French and American Revolutions were also well-incubated by coffeehouses. A coffeehouse gives people a place to congregate, meet new people, and converse without getting tipsy, which , coupled with a rich history of intellectual innovation creates a place that fosters community and intellectual discourse. I'll end this article with a quote by the great French historian Jules Michelet who romanticizes the coffee-induced revolution better than I. "Paris became one vast cafe. Conversation in France was at its zenith . . . . For this sparkling outburst there is no doubt that honor should be ascribed in part to the auspicious revolution of the times, to the great event which created new customs, and even modified human temperament - the advent of coffee. Its effect was immeasurable . . . . The elegant coffee shop, where conversation flowed, a salon rather than a shop. changed and ennobled its customs . . . . Coffee, the beverage of sobriety, a powerful mental stimulant, which unlike spirituous liquors, increases clearness and lucidity; coffee, which suppresses the vague, heavy fantasies of the imagination, which from the perception of reality brings forth the sparkle and sunlight of truth"