Tuesday, August 21, 2012

Iced Tea

Since arriving in Los Angeles, I have found a new appreciation for iced tea. Iced tea inherently lacks the aromatic complexity of hot tea, but when it's over 90 degrees outside, cold beverages have certain advantages.

Fortunately, iced tea is nowhere near as challenging to make as iced coffee. One of the main reasons that my interest in coffee has waxed and my interest in tea has waned is that tea is really quite simple to make. Tea need not—should not—be ground before brewing, as coffee must. Eliminating the grinding step greatly simplifies matters, given how crucial controlling the coarseness of the grind is to brewing coffee.

The second reason that tea is easy to make is that tea seems to be relatively insensitive to extraction (see previous post for info on coffee extraction). Strength is still important, since overly strong tea is unpleasantly tannic, and weak tea is, well, weak. But brewing tea to the same strength with a longer steep time and less tea vs. using more tea and a shorter steep time yields fairly similar results (up to a point). If you tried the same thing with coffee you'd see dramatic differences, due to the differing percentages of the coffee solids that would be extracted. Tea's insensitivity to under- and over-extraction also explains why one can steep tea leaves multiple times, whereas brewing with used coffee grounds... not so tasty.

Since under-extraction is not a big concern, brewing hot tea at double strength and pouring it over ice immediately after steeping yields good results. Brewing tea (regular strength) at room temperature for 8–16 hours also works, provided you protect the tea from oxygen; mason jars work well for this purpose. Hot-brewed and cold-brewed iced teas have different flavor profiles, but they're both agreeable to my palate. I've found cold-brewed tea to be a bit clearer in appearance, but your mileage may vary. One advantage of hot-brewed iced tea is that it can be a more efficient use of tea, if you incorporate a second steep using a longer steep time and adding less ice.

More important than brewing method is the kind of tea used. Some teas make really terrible iced tea. My current favorite iced tea is a blend of two parts Ceylon to one part Keemun. The brisk citrus flavor of Ceylon makes a fantastic base, and the intense floral/incense notes of the Keemun add sweetness and complexity.

Finally, there's the question of sugar and lemon. I prefer unsweetened tea, but sweetened iced tea has a long tradition. I've always been tempted to sweeten tea with honey, since it tastes nice and is (maybe) healthier than sugar. After a few experiments, though, I can't recommend it, unless you really like the taste of honey. The problem is that honey has such a strong flavor that it tends to overpower the flavors of the tea itself. So stick with plain old refined white sugar or nothing at all, unless you're making chai.

I sometimes like lemon in iced tea, because the acidity adds a refreshing brightness and complements the citrus flavors of Ceylon tea. But lemon can easily overpower the tea's flavor, so I usually add only a very small amount—maybe 1/16th of the juice of a lemon. I recently had an unusual idea that I think is worth trying, which is to bypass the lemon and add acid directly to the tea. Homebrew shops sell acid blends for winemakers to use to add acidity to their wines. These blends contain several naturally occurring acids, namely malic, citric, and tartaric acids. Malic acid is found in high concentrations in apples, and citric acid is highly concentrated in (surprise!) citrus fruits. Tartaric acid is a bit less familiar, but wine grapes contain a balance of all three acids. My goal in using an acid blend would be to add acidity to the iced tea without the strong aromatic flavors that lemon also contributes.

Tuesday, August 14, 2012

Iced Coffee, Part 1: Hypotheses

In preparation for further brewing of coffee stouts, I've decided to again try to master iced coffee. In this post, I will summarize the hypotheses I've come up with to explain my previous experiences with making iced coffee, and lay out future plans for testing these hypotheses.

The challenges of iced coffee emerge chiefly from two sources: oxidation and under-extraction. Oxidation results in the acrid taste of stale coffee, and is a function of oxygen exposure, time, and temperature. Oxidation is a concern for cold-brewed coffee because of the long brewing times necessary to achieve proper levels of extraction. Oxidation is also a concern for hot-brewed iced coffee if it isn't chilled immediately, because oxidation occurs much more rapidly at high temperatures. Oxidation is especially worrying for me, because the effects of oxidation increase over time, and I want my coffee stouts to last much longer than iced coffee is expected to.

Extraction refers to the percentage of solids dissolved into the water during brewing. One intuitive way to think about extraction is as brewing efficiency—but higher efficiency is not always better. According to the SCAA, ideal extraction is about 20% (interestingly, this is true for both brewed coffee and espresso). Coffee with much less than 20% extraction is said to be under-extracted; coffee with much more than 20% extraction is said to be over-extracted, which is even worse.

Extraction is a function of a number of variables, including: brew ratio (coffee-to-water ratio), grind, water temperature, brew time, and agitation. Crucially, brew strength is distinct from amount of extraction: strength equals brew ratio multiplied by amount of extraction. Therefore, if a high enough brew ratio is used, it is quite easy to make very strong but under-extracted coffee, as in the top left corner of this chart:

Under-extraction in brewed coffee often yields a musty or tea-like aroma that I find particularly unpleasant at cold temperatures.

One method of brewing iced coffee that has become popular recently—sometimes under the moniker 'Japanese iced coffee'—is to brew hot coffee directly onto ice, compensating for the dilution the ice produces by using half the usual amount of brewing water. I've tried this method many times over the past few months, using both Hario V60 brewers and press pots, with consistently disappointing results. Specifically, every attempt yielded coffee with the musty aroma that I now (tentatively) identify as under-extraction. Varying the amount of coffee I used didn't seem to help.

So why did the brew-onto-ice method fail? The problem, I think, is this: by reducing the amount of brewing water so dramatically, the percentage of solids extracted from the coffee grounds dropped precipitously. Less hot water passing through the coffee, less solids extracted from the coffee.

There is, therefore, a trade-off inherent in the brew-onto-ice method. Keeping the total coffee-to-water ratio constant, one can vary the ratio of hot water to ice. (Note that ice should always be measured in weight, since the amount of ice in a given volume will vary depending on the size of the ice cubes.) Adding more hot water and less ice will result in better extraction, but also slower chilling of the coffee, possibly leading to oxidation. Adding more ice and less hot water will result in faster chilling, and hence less risk of oxidation, but also lower extraction. I believe that there is a ratio (or range of ratios) at which neither under-extraction nor oxidation are major concerns, but I have yet to determine where this sweet spot lies.

One strategy to compensate for the decrease in extraction caused by the reduction in hot water is to use a finer grind. This is a technique already in use by my former employer, but until now I did not fully understand the reasoning behind it. Using a finer grind increases the strength of the coffee by raising extraction, while reducing the amount of water (or increasing the amount of coffee) increases the strength of the coffee but decreases extraction. In order to maintain optimal extraction, therefore, an increase in the brew ratio should always be accompanied by a finer grind and/or an increase in brewing time. (In drip methods of brewing, a finer grind also increases the brewing time.) This is a bit counter-intuitive, but I'm pretty sure it's true!

In order to test these ideas and try to make better iced coffee (and hence better coffee stouts) I plan to brew iced coffee using several different methods.

1. Traditional cold-brew. 80 grams of coffee per liter of room temperature water. Medium grind. 18 hour brew time (room temperature).

2. Barismo-style cold-brew. 80 grams of coffee per liter of 40˚F water. Medium grind. 18 hour brew time (refrigerated).

3. Hario V60 brew-onto-ice. 50 grams of coffee per liter of total water. (Variable hot water/ice ratio). Medium-fine/fine grind.

4. Full-immersion hot brew poured onto ice. 50 grams of coffee per liter of total water. (Variable hot water/ice ratio). Medium-fine grind (or medium-fine/fine grind for a direct comparison with method 3).

In order to filter the cold-brewed and full-immersion coffee I will probably just use the Hario. Any oxygen introduced shouldn't affect the flavor in the short-term. In any case, I will taste the coffee before and after filtration. In the long run I would like to find a way to filter without exposure to air, and without having to use a coarse grind (as a press would require). Hario makes an iced coffee maker called the Mizudashi that might work. The Eva Cafe Solo is also an option. Or a cotton sack, perhaps.

Results to come.

Thursday, August 9, 2012

Wednesday, August 8, 2012

Los Angeles

New blog! This will be a bit wider in scope than Angry Monocle, covering coffee and tea as well as beer.

Brewing beer in Los Angeles will present a few new problems. Seattle has some of the softest, purest water in America, while LA decidedly does not. For coffee and tea, filtered water should suffice, but I don't think I want to wait for six gallons of water to run through a Brita, so for beer I will either use packaged drinking water, or, more ambitiously, use reverse osmosis water and adjust the water chemistry according to the beer I'm brewing. Stouts, for example, benefit from harder water to balance the acidity of the roasted grains.

Los Angeles is also a bit warmer than Seattle. At the moment, it's 7pm and 84˚F. If I want to brew this summer, I'll either need to invest in a temperature control system or exclusively brew saisons, which like to ferment hot.