Curious Cook in the New York Times: Vodka in the fish fry

My column in today's New York Times Dining section is about a batter for fried fish developed at The Fat Duck, Heston Blumenthal's restaurant west of London. I first enjoyed the very crunchy crust it makes last spring, when Christopher Young, the restaurant's research manager--yes, they do enough research at The Fat Duck that it needs managing!--demonstrated it at the Greystone campus of the Culinary Institute of America. The key ingredient is alcohol. In an email, Chris explained how vodka ended up in a beer batter. Heston and his colleagues were doing a cookbook and TV series on popular British foods, and developing an updated recipe for fish and chips.

The story with the fish batter was that we had developed a really fantastic batter recipe using special starches from National Starch. By using these, along with the siphon to create a very irregular foam structure (an idea that based on the work of Julian Vincent at Bath University and the mechanics of brittle fracture) we created a really outstanding batter that would cook fast enough so that the fish wasn’t over cooked, but stay crisp for a good 20+ minutes. The only downside to this was that no one could recreate this batter at home.

We mostly dealt with this “pickle” by waiting for divine inspiration. That occurred one afternoon at my house when I was reducing alcohol for a sauce and while I had my back turned it boiled away to nothing. I was reminded that alcohol takes far less energy to evaporate than water. I thought it might be possible to reduce the amount of water in the batter by replacing it with alcohol and creating a batter that would cook faster. The added bonus was that alcohol destabilizes the foam, which creates a more inhomogenous structure, which makes the batter crisper!

There was a bit of trial and error, because you do need some gluten or the batter just “blows” off the fish. It seems that a final alcohol content of around 20% seems about right.

Inspiration favors the prepared mind!
For the other big advantage that alcohol brings to a batter, see my column. The Times also gives an adaptation of the Fat Duck's recipe for siphonless cooks.

Curious Cook in the New York Times: Of mice and wine, and rice

In today's dining section I write about the surprising connection between an obnoxious off-flavor in wines and the prized flavor of aromatic rices.

Check back in a couple of days for more news about rice.

_____________________
Snowdon, E. et al. Mousy off-flavor: A review. J. Agric. Food Chem. 2006, 54, 6465-74. http://dx.doi.org/10.1021/jf0528613

Progress in sparkling wines: bubbles and flow

A progress report from Gérard Liger-Belair, the world authority on wine bubbles, and his quest to define the ideal glass for enjoying the effervescence of champagne. Bubbling really stirs up a glass of wine, and if you're going to etch a glass to generate bubbles, you'll need to adjust the pattern to the glass shape.

When a sparkling wine is poured into a glass, the bubbling delivers aroma and pleasantly irritating carbon dioxide to our nose. At the same time it depletes aroma, gas, and its own activity. If a glass of sparkling wine bubbles vigorously, it loses the advantages of effervescence quickly; if it bubbles too slowly, it has no charm. Liger-Belair has shown that steady, regular, "pleasing" bubbling is caused by plant dust: microscopic cellulose fibers from the dish towel or released into the air from such things as clothes and paper. Intentionally scratching or etching the bottom of the glass creates pits that induce more predictable bubble formation, but the bubbling is faster, coarser, and more chaotic.

For this new study, Liger-Belair and colleagues added tiny reflective plastic beads to bottles of champagne, poured the wine into glasses with bubble-forming pits etched just above the central stem, illuminated the glasses from the side with a laser beam, and used time-lapse photography to follow the movements of the beads.

They found that bubbles rising from the bottom of the glass pull the surrounding liquid along with them, setting up regular lines of flow from the bottom of the glass to the top and then back down. In a tall flute, the lines of flow run through the full volume of the liquid, and deliver bubbles directly to the edge of the glass to form the desirable collerette or bubble collar. But in a broad and shallow coupe, the flow lines ran only in the center of the glass, leaving a surrounding "dead zone" of little or no effervescence that prevented the delivery of bubbles to the edge.

So glasses with different shapes will have to be etched with different patterns of pits to deliver the same desirable effervescent effects. The large surface area of wine exposed in a coupe also means a more rapid loss of gas, so the etching in a coupe may need to be sparser than in a narrow flute.

Next on the agenda for the Liger-Belair lab: "quantitative measurements of the release of volatile organic compounds and carbon dioxide from glasses showing various engravement and shape conditions, our final goal being to scientifically identify the best glass for the tasting of champagne and sparkling wines in terms of gas discharge and flavor release."

In the meantime, fans of sparkling wine have more to look for in the glass.

__________________________________

Liger-Belair, G. et al. Visualization of mixing flow phenomena in champagne
glasses under various glass-shape and engravement conditions. J. Agric. Food Chem. 2007, vol. 55.
Published on the web: http://dx.doi.org/10.1021/jf062973+

In the dark: olive oil, milk, butter, and beer

In my last post I mentioned that olive oil is best stored in the dark. The same is true for milk and butter and beer. It's turning out that all these foods are sensitive to light for similar reasons.

When milk is exposed to light, especially sunlight or to the fluorescent lights in a market, it develops an unpleasant, sulfurous "sunlight" or "lightstruck" flavor. It's been known for a long time that the vitamin riboflavin is involved in this reaction, and a recent report by David Min and colleagues at Ohio State summarizes the current understanding of what happens. It turns out that the off flavor signals significant nutritional losses. When riboflavin absorbs certain frequencies of light, it catalyzes the conversion of ordinary oxygen to an especially reactive "singlet" form. Singlet oxygen in turn attacks the milk fat, producing fragments with grassy aromas, and it attacks the amino acid methionine, producing a compound with an overcooked-vegetable aroma (dimethyl disulfide). It also attacks both the riboflavin that made it, and vitamin D, which we need to absorb the calcium in milk efficiently.

Exposure to light also damages the flavor of beer, which accumulates a characteristic "skunky" sulfur compound known as MBT (3-methyl-2-butene-1-thiol). Earlier studies had shown that MBT is produced when flavor compounds from hops, the hop acids, react with sulfur-containing compounds. But the hop acids themselves don't absorb the wavelengths of light that cause skunkiness. It appeared that that the energy for the reaction was supplied indirectly, and probably by the same molecule that damages milk-- riboflavin! Richard Pozdrik and colleagues in Melbourne, Australia have strengthened the case against riboflavin by showing that light absorption by riboflavin in beer correlates well with the development of skunkiness.

According to a new study of butter done in Norway and Denmark, riboflavin isn't the only "photosensitizer" in dairy products. J.P. Wold and colleagues found that traces of chlorophyll and related substances in butter also absorb light energy and transfer it to other butter components, thus causing oxidation reactions and unpleasant flavor changes. This makes sense, because absorbing and transferring light energy is exactly what chlorophyll is designed to do in the leaf of a living plant. And it's the lovely green chlorophyll and related molecules that are the major photosensitizers in olive oil.


So it's a good idea to buy and keep all these foods in opaque or at least dark containers. If they're in clear glass or plastic, or the butter is wrapped in light wax paper, then keep them in the dark as much as possible.

____________________

D.G. Bradley et al. Effects, quenching mechanisms, and kinetics of water-soluble compounds in riboflavin photosensitized oxidation of milk. J. Agric. Food Chemistry 2006, 54, 6016-20.

R. Pozdrik et al. Spectrophotometric method for exploring MBT formation in lager. J. Agric. Food Chemistry 2006, 54, 6123-29.

J.P. Wold et al. Active photosensitizers in butter detected by fluorescence spectroscopy and multivariate curve resolution. J. Agric. Food Chemistry 2006, 54, 10197-10204.

Curious Cook in the New York Times: Absinthe and champagne

In today's dining section I write about a recent analysis of the fact and fiction surrounding absinthe and its distinguishing ingredient, wormwood. And about the latest from the bubble laboratory of Gérard Liger-Belair, deep in champagne country. And what happens when you mix absinthe and champagne.

Anyone who enjoys sparkling wine will love Professor Liger-Belair's informative and poetic book Uncorked: The Science of Champagne, published by Princeton University Press in 2004.


Lachenmeier, D.W. et al. Absinthe: a review. Critical Reviews in Food Science and Nutrition, 2006, 46: 365-77.

Liger-Belair, G. et al. Modeling the kinetics of bubble nucleation in champagne and carbonated beverages. J. Physical Chem. B 2006, 110: 21145-51.

Liger-Belair, G. Et al. Champagne experiences various rhythmical bubbling regines in a flute. J. Agric. Food Chem. 2006, 54: 6989-6994.

Cognacs contain more dissolved taste substances than other spirits

In a French study of the solids content of various spirits, cognacs and other brandies turned out to be more than 1% by weight polyphenols, carbohydrates, and caramel materials, all of which the spirits extract from the wood barrels in which they're aged. Armagnacs and rums contained about half the solids of cognacs, bourbons about a fifth, and whiskies a tenth. From 4 to 51 samples of each spirit were tested. These are large differences, and indicate that brandies should often seem more astringent, sweet, and full-bodied than their distilled cousins.

Picque, D. et al., J. Agric. Food Chem. 2006, 54 (15) 5220