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Inquiring Winemaker TIM P A T TERSON Sift Through Facts In Solids and Wine is considered a more noble beverage than, say, bubble tea, with its scads of tapioca pearls in the mix. In the quest for great liquids, winemak- W ers rarely give solids much thought, except for making sure to get rid of all of them before bottling. But that 100% liquid wine starts out full of all manner of solid stuff, and the amount and composition of this indissoluble matter can matter, big time. A quick review of the relevant literature unearths an astonishing number of things solids can, might or will do, especially for white wine fermentations, including some contradictory findings and some things that show up in the lab but rarely in com- mercial-scale winemaking. It would be tempting to just say—as the great majority of winemakers do—that the plan is to get rid of most but not all of the juice solids before fermentation and leave it at that. But there is enough evidence to suggest that managing solids more carefully could be a way to fine-tune wine style—if only we knew how to do it with certainty. Sludge composition 101 The composition of solids in white grape juice—juice lees—is all over the map; it's a "them," not an "it." There are sure to be itsy bits of skin, pulp, seeds and stem jacks in some proportion or other. There may be mold, or mold byproducts, as well as dirt and perhaps residues from vineyard spray- ing. Figure in some stray feral microbes, 56 Wines & Vines AUGUsT 201 1 ine is, ideally, all liquid; that is, we don't gener- ally want to see things floating or swimming in the glass. This is one of the many reasons wine plus an insect part or two (there are, in truth, no strictly vegetarian wines) and the occasional shredded gum wrapper. Finally, there may be some solids intentionally added in the cellar: yeast hulls, powdered oak tannins and so on. Every batch of wine is complicated, and every batch is differ- ent, depending on the variety, the vintage, vineyard practices and the equipment and protocols used for crushing and pressing. The grape-derived solids break down fur- ther into many components: several flavors of polysaccharides, mannoproteins, mineral salts, nitrogen, tannins and on and on. Plus multiple forms of fatty acids—although, fortunately for the health-conscious, more of these are unsaturated than saturated. The amount and composition of this indissoluble matter can matter, big time. We know this long roster of likely con- tents from lab experiments focused on parsing the sludge into its component parts. In winery practice, however, all we usually know is how much we have—the overall volume of solids compared to the volume of liquid—and we can observe that the heavier particles settle first, leading to a stratified sediment that changes particle size (bigger to smaller) and color (browner to greener) from bottom to top. It is a rare winery indeed that performs analysis to determine what exactly is on hand. Contemporary conventional white wine- making wisdom says that white juices need some solids (since over-clarified juice can lead to stuck fermentation), but not too much, which can result in reduced aromas and other off-elements. There is no con- sensus about how much is just right. Most winemakers, seeking fruitiness above all else in white wines, aim for somewhere be- tween 1% and 2% of solids by volume and do some form of settling, draining, racking or centrifuging to get there. Whole-cluster pressing generally achieves that target range without further need for clarification. Highlights • The solids that come with white grape juices are not just something to get rid of before bottling; they can have significant effects during fermentation and beyond. • The level and composition of solids affects the rate of fermentation and the levels of many compounds—good and bad—that get created. • Pre-fermentation solids also can affect post-fermentation clarification and aging. This practice more or less works, with only juices at the extremes—water-clear or highly sludgy—causing obvious problems. If it ain't broke, don't fix it. But there are indications that the details of juice lees composition matter, and that if we had ways to get better analysis and control of solids—plus additional research on this unglamorous topic—we might be able to use solids management as a tool to fine- tune wine style. Cornucopia of effects Solids have been linked with an amazing number of biochemical reactions. The idea that white fermentations need "some solids but not too much" has been demonstrated repeatedly in controlled experiments. Juice that has been clarified ferments more