Wednesday, April 29, 2009
The Bikerman Coefficient
I hate foam. I hate it with an irrational passion that is akin to my hatred and fear of snakes. I hate it in all its incarnations; sea water foam that collects in sickly yellow pools under piers, styrofoam that grates on my teeth with a high pitched dog whistle squeal, couch foam, foam fingers, the foam that exudes from various bodily orifices on episodes of 'House', dish detergent foam that invaded rivers and streams until Rachel Carson pointed the accusatory foam finger at it in 'Silent Spring'; I hate it all. The present fascination of haute cuisine with various types of foamed food is beyond inexplicable to me. The idea that any food could be made more appetizing with the addition of foam to me is a heresy perhaps exceeding that which resulted in the burning of the Czech Jan Hus at the stake in the 15th century.
Having said that, I must admit, there are two incarnations of foam that are not objectionable to me; that on top of beer or on cappuchinos. In both these cases I tolerate it. I suspect it is because I look at it not as real foam but as some kind of fizzy fashion accessory, such as is implied by the use of the word 'head' in relation to beer, (though most people don't look at a head as a fashion accessory, after a few beers it generally can be) and the prefix 'Cappu', implying, in Italian, 'hat'.
Obviously, being a winemaker, (I am told that is what I am now), the inevitable occurrence of foam at certain points in the winemaking process is both fascinating and horrifying to me. It appears at two distinct junctures in the process; first during what is the 'maceration' period of the primary fermentation, when the cap forms on top of the wine and secondly at bottling when a colloidal foam forms in the headspace of the bottle. In the first case the foam is far more pronounced and substantial (as measured by the Bikerman coefficient) in red wines, and in the second case moreso in white wines. The formation of the foam cap in the must of red wines is a welcome and well studied phenomena as well as an integral part of the winemaking process. The formation of foam at bottling is regarded as a mere nuisance and is generally regarded as having no effect whatsoever on the finished product.
Part of the task of the winemaker is to pay attention to things that you have been told not to pay attention to; I call this the 'Wizard of Oz' rule as this process of peeking behind the winemaking curtain is almost always immediately disheartening and only secondarily and eventually productive in helping you reach your goal. So, this week when I was bottling the Cayuga White I happened to notice that the foam produced in the bottle at filling seemed unusually durable and stable, I decided to attempt to yank the curtain aside, so hold on to your dog, Dorothy, it's about to get bumpy, again.
There were two possible culprits that immediately presented themselves; two components of wine that might produce sufficient heightened surface tension to noticeably affect persistence of bubbles, to result in foaming in the finished wine; fatty esters (not one of my relatives) and polysaccharides, both naturally occurring compounds, both also components of glycerine. I immediately dismissed fatty esters. My reasoning was as follows; since Cayuga White has a notoriously low finished alcohol content; this low alcohol content is probably due to the fact that fatty esters tend to break down into volatile ethanol and water (as opposed to fermentation which produces only alcohol). The assumption that it's low alcohol content was probably due in part to the increase in water content as these compounds broke down seemed reasonable. This left me with polysaccharides.
Polysaccharides are interesting little buggers and the fact that they are utilized as foaming agents in the pharmaceutical industry seemed to lend credence to my theory. As it turns out, since they are also the component of the yeast cell wall that when the yeast cells dies and breaks down producing foaming in the must, the fickle foam finger of fate seemed even more firmly fixed on their malfeasance and Occam's Razor further suggested it was at work in both instances of red and white wine.
This led to the secondary question as to why, since the byproducts in the degradation of yeast eventually precipitate out, why would the polysaccharides in the Cayuga White remain in suspension. The answer I have come up with is this: Cayuga White is a particularly cold hardy variety and polysaccharides are implicated in the production of the natural anti-freeze that protects grapes in winter hence it is reasonable to assume the must has a higher concentration of these. The addition of sulphur in the form of Potassium Metabisulfite in the winemaking process causes the formation of sulphuric esters of the polysaccharides in suspension which is more pronounced in Cayuga White because of the higher polysaccharide content. These long chains of sugar-like compounds that are bound together by a fatty ester produce durable foam. QED. Whew! Too much technical jargon but here's the kicker.
Certain polysaccharides, particularly the Sulphuric Esters of Polysaccharides also have a very specific effect on the human circulatory system called 'Brakykinin'. In essence they are powerful vaso-dilators, i.e. they have the tendency to lower your blood pressure. Hence, it seemed that the very effect which was raising my own blood pressure as I bottled the wine and cursed the foam, contained the antidote for that very condition. Ironic! Do you see now how insidious foam is! So, the next time you are at a baseball or football game waving that foam finger in the air, it would behoove you to think how treacherous and tricky foam can be, and to consider the possibility that foam based fashion accessories may in fact produce the opposite of the intended effects and cause your team to lose instead. Just something to consider. And for all you chefs out there intent of finding new uses for foam in the culinary arts, a cautinary word, 'beware of the nefarious mousse!' Now, where is my cappuchino?