Thursday, April 24 2008

When You're Hot, You're Hot

How do you say, 'Stick 'em up', in Centigrade?

I gave a couple of lectures on operational efficiency at the Fermenters Guild of Ontario on the weekend. They went pretty well, despite persistent jet-lag on my part and a certain amount of profuse sweating from the breakdown of the air conditioner. That was actually quite appropriate, given that a big chunk of my lecture was about temperature control in the On-Premise Operation.

Quick review: On-premise is a home winemaking store where you buy the kit, but don't take it home. You pay an extra fee, and the salesperson takes the kit back, helps you mix it up, you pitch the yeast and wander off, happy as a bivalve mollusc. In six or eight weeks 9by arrangement) you return to find that magic elves (usually the owners relatives or some other downtrodden cellar dweller) have racked, fined, stabilised and filtered your wine. The next step is bottling, labeling and putting on capsules. It's cool on a lot of levels. People who live in condos don't have to worry about space for fermenting, people with technical issues (they still own VCR's and they still flash '12:00') don't have to learn the intricacies of winemaking, and the magic elves do all the clean-up.

Temperature control is deucedly important, but it's one of those things that never gets the attention it deserves, like international monetary policy, or when those flying cars and vacations on the moon I was promised back in grade school are going to get here. The bottom line is, most people make wine too cold.

Why? A variety of factors. Some folks filter their water, but mostly only the cold line. Kits made with only cold water are too cold at yeast pitching time, which leads to very slow onset of fermentation. This is because the dried yeast that get pitched into the must have to rehydrate before they can go to work. Rehydrating allows their integument (outer skin) to soften up and allow the passage of nutrients (sugar) into the cell, and waste products (alcohol and carbon dioxide) out. Since their integument is a complex series of layered fatty-acid esters, it's essentially grease. Sounds weird, making an organism out of grease, but if you ate Mennonite food like I did for the first half of your life, you'd see how it's possible, and on a microscopic level, the surface tension on a teeny-tiny grease droplet is so intense, it's actually as strong as steel. Who knew?

But it's still grease. Soak your bacon platter in cold water and I don't care how much dishwashing liquid you use: your dishes will still be coated in grease. But switch to warm water, and the grease will soften and slough off. Same deal with yeast cells. Warmer = gooder, as far as they're concerned, because starting quickly and breeding as rapidly as possible lets yeast can tie up all the nutrients and resources necessary to complete cell-wall synthesis and new yeast production (these yeast are kind of like those really big guys ahead of you in the buffet line-up–kiss that plate of shrimp goodbye!).

Speed of fermentation is important because the sooner the ethanol level rises, the sooner the wine is protected by the sanitising power of that alcohol, and a thorough fermentation doesn't leave any sugars or nutrients for other organisms to spoil the wine post-fermentation.

In addition to this, low temperature fermentations run a risk of slowing, stopping altogether, or of retaining excessive amounts of carbon dioxide gas after fermentation is complete. Unless you're the sort of winemaker who's happiest preparing secondary yeast cultures and monitoring fermentations on a daily basis and checking for residual sugar, you might be in for a bunch of trouble with a stuck or stopped fermentation. In an On Premise operation this is disaster, as most folks want that wine in eight weeks, not eight months.

Also, carbon dioxide retention has a lot of downstream implications for clearing and flavour development. Gassy wines don't clear and are often stinky. Plus, who wants fizzy Cabernet?

In the course of my lecture I showed off my Digital Infrared Thermometer (pictured above). It's one of those gadgets that's so much better, so profoundly improved over the past, that it changes everything. It reads almost instantly, is incredibly accurate, and lets you survey two or three hundred carboys in a couple of minutes. You can tell right away if your must is warm enough for pitching, or if you need to work on temperature regulating your fermenting area.

The one I use is the Reed ST-882. I got it for a hundred bucks or so from a lab supply company. It's so incredibly useful that I tote it around and find things to point it at in my spare time. Got a fever? I can tell from across the room! Is that sugar syrup ready for peanut brittle? I can tell from the house next door! It has an aiming laser that allows you to precisely measure your intended target. Of course, that lead me to name my thermometer, 'Goldfinger', in honour of villainous lasers everywhere:

Do you need your own digital infrared thermometer? Well, if you have an on-premise operation, then yes, you do. Go buy one right this minute. For home use? I'd have one in any case, if only so I could check the temperature of the oil in my turkey fryer, or the pot of boiling lead I keep by my side at all times. Eventually you may tire of pointing it at random objects, but that hasn't happened to me yet.

Posted by Tim AT 4:47PM

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