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WINEMAKING potatoes. Generally, we want to drink our wines with the pot roast, not to have them smell like it. In yielding fruitier wines, juice clarifica- tion seems to promote the retention of all those nifty volatile esters that white wines exude. Excess solids depress the fruit, hide those esters and let the sulfur-related aro- mas move front and center. But wait, there's more. The volume and type of solids at fer- mentation can strongly affect the later clarification of the finished wine. A small amount of botrytis can yield certain polysaccharides that stubbornly resist clarification. (But, weirdly enough, a very, very small amount of botrytis can generate a large amount of pectinase in response, which is highly effective in ad- vancing clarification.) The Australian Wine Research Insti- tute has reported that during fermenta- tion, yeast can produce haze-protective mannoprotein material (HPM) that re- duces the level of protein haze later on, and that this HPM is produced in greater volume during fermentation than later through the slow disintegration of yeast cells during aging. The implication here is that if you could collect a bunch of HPM, you could add it as a bonus solid to your next fermentation and have less haze to worry about later. Mannoproteins—proteins found in yeast cell walls that contain mannose, a form of sugar—show up in more and more wine analysis and research. In the winery, they are a boon to mouthfeel and are an important part of what gets pulled out from spent yeast cells through sur lie aging. In fermentations conducted with too high a level of solids, however, the mannoproteins may be coaxed out pre- maturely, at which point they adsorb onto the solids, fall out of solution and aren't around later when it's sur lie time. Is it just me, or is all this making your head hurt, too? The plethora of find- ings and semi-well-founded speculations mainly come from small-scale lab work, microvinifications that don't always par- allel commercial realities. (Kind of like the relationship between rat studies and human trials for pharmaceuticals.) It's also clear that the endless variation and complexity of juice composition means that what solid X does in one juice may not be repeated in the next one. The vol- ume and composition of solids clearly have a significant effect on fermentation and the resulting wine; what exactly is happening in a specific fermentor is any- body's guess. Measurement methods While we wait for the magic instrument or additive that can size up the sludge and pluck out just the bad fatty acids (for ex- ample) and leave the good ones in, there remains the issue of knowing the sheer vol- ume of solids. This much at least is essential to conscious winemaking: measuring the solids in each batch of juice, keeping re- cords, evaluating the results, adjusting prac- tices over time. When grape sources change or reception equipment gets updated, solids measurement needs to be revisited. Some winemakers "measure" solids simply by eyeballing the juice after 12-24 hours of settling. The standard here is that the juice be "opalescent"—letting light through but slightly milky, like the ap- pearance of an opal. Opalescent is a fine and fancy descriptor, but the accuracy of purely visual methods is in doubt. One step up is putting a juice sample in a clear, calibrated cylinder, letting it settle and do- ing the math. While hardly ultra-precise, this method used consistently over time can more or less do the job. Typical S I H A Wines & Vines AUGUsT 2011 59