Saturday, January 10, 2015


As my relatively leisurely elective period comes to an end, I've been enjoying Benoit Mandelbrot's quirky autobiography. I'm generally annoyed by novels whose protagonists live a sort of charmed life during which they are prominently inserted into most of the major events of the era*. Mandelbrot interacts with virtually every major scientific and mathematical figure alive during his scientific upbringing, but only occasionally due to charm. His uncle was part of the Bourbaki, his father a practical genius, he himself a genius of all sorts. It's fascinating to read how his interactions with the great (largely) men of the era laid the foundation for one of the most ingenious mathematical advances ever to be made. Nowadays, one tends to be pigeonholed out of being a scientific polyglot; reading this autobiography, I wonder just how much of a drawback that is. And I wonder what happened to Benoit's brother Leon, and whether Leon ever felt jealous of living in Benoit's shadow. If this were a novel, Benoit might have some insights at the denoument of a great family disagreement...

Oh, and it's cold. Just the weather for dishes like shakshuka with spinach and Indian spices, or persimmon-turmeric oatmeal with plenty of grated fresh ginger and a hit of blood orange juice.

Good books, warm food... I'll just stay inside, thanks.

*For an exception, see Les Bienveillantes by Jonathan Littell. For not an exception, see The Long Ships by Frans Bengtsson.

Monday, January 5, 2015

Edible biology

Proteases are fun! A protease is an enzyme that breaks down protein by destroying the linkages between amino acids. Proteases destroy those linkages, which are called peptide bonds, via hydrolysis, in which the oxygen of one of our cells' oh-so-abundant water molecules stuffs its way into a chemical bond, booting off one of the components (in not-quite-accurate layman's terms, that is, but it'll do).  One of the more interesting things about many proteases is the catalytic triad, or a trio of amino acids that work together to catalyze, or speed up, this hydrolysis. Their chemical and biological mechanisms are pretty nifty (particularly the classic serine-histidine-aspartate triad), but what is even cooler is that species all over the genetic map possess proteases with catalytic triads in a beautiful example of convergent evolution. What this means is that the catalytic triad arose independently about two dozen times because of the sheer chemical elegance of those arrangement(s). Even better, some species of protease-packed plants are edible.

Kiwi, papaya, and pineapple are some of the most notable protease-containing foods; nota bene that none of them can be set in gelatin unless canned or otherwise preserved first, since the peptide bonds that give gelatin its structure will rapidly be destroyed. Industrially, the papaya protease--conveniently named papain--is used as a meat tenderizer. Ficin, a protease derived from the fig tree itself rather than the fruit, can also do this.

"Yes, Hannah," you're saying. "I know all about papain, and pineapple's ability to dissolve gelatin has been the bane of housewives since the 1950s." Fine. But did you know that everyone's favorite rhizome also contains a protease?

Ginger protease, or zingibain, can actually be used to make a milk pudding (or cheese, but that's another story). Here's how it works: normally, milk proteins called caseins aggregate into balls called micelles. Micelles of any sort have hydrophilic, or water-friendly, components on the outside, and hydrophobic components pointing inward. In this case, kappa-casein (heretofore written as K-casein) is on the outside of the micelles. Zingipain cleaves K-casein (specifically, at a proline residue), leaving a hydrophobic component called para-K-casein behind... and all of a sudden, those beautiful micelles stick together, and the milk sets.

Unfortunately, zingibain is a fairly tim'rous beastie. If heated above 150 Farenheit, it denatures--or loses its structure--almost completely, per this paper.  It also degrades fairly quickly; the half-life is only 20 minutes at about 85 degrees Farenheit, but according to this paper, the addition of simple ascorbic acid--also known as vitamin C--dramatically increases that half-life. The science of that phenomenon is adequately explained in both the citations above.

That first paper also mentions that zingibain has its peak activity in a very narrow temperature window of 60 to 65 Celsius... and yet I saw so many recipes for this that called for milk to be "nearly simmering" or something like that. Sheesh. Break out the candy thermometer!

Ginger milk pudding

325 mL milk
40 g sugar
37 g ginger juice

In a small saucepan, mix the milk and sugar. Heat gently; you want to add the ginger juice at a target temperature of 145F. Meanwhile, grate the ginger (I used my delightful microplane) and squeeze out the juice using your hands, cheesecloth, or a strainer. When the milk and sugar are at the appropriate temperature, pour the ginger juice in over the surface of the milk and do not stir. Allow to set for about seven minutes, and enjoy the sweet taste of science.

Sunday, January 4, 2015

This year

Oh, John Darnielle, you and your eerily perfect combination of morbid and catchy. How do you do it? (Actually, morbid and New Year's Eve seem to go together in the arts; two of the numerous books I've recently finished feature terrible things happening to morally ambiguous people on that momentous occasion. Of the two, I'd more strongly recommend Ten Thousand Saints, by Eleanor Henderson. Despite my recent glut of  books featuring tortured adolescent-to-young-adult male protagonists, its unique perspective on a more dangerous New York was striking, to say the least.)

Ringing in 2015 with this and other combinations... like elderflower, berry, and citrus. What's not to love about a berry pastry cream-filled Meyer lemon cupcake with fragrant St. Germain frosting and a sprinkle of toasted almonds to cut through all those florals?

Lemon cupcakes
2 sticks melted butter (room temperature) or oil
3/4 cup Meyer lemon juice
1/4 cup water
1 1/3 cups sugar
2 eggs
1/2 cup Greek yogurt
2 tsp vanilla
2 tbsp lemon zest
2 cups flour
3/4 tsp salt
1 1/2 tsp baking soda

Whisk the sugar into the butter/oil, then add the lemon juice, vanilla, water, yogurt, eggs, and lemon zest. Slowly whisk the dry ingredients into this mixture. Fill muffin tins 3/4 of the way to the top and bake at 350F for 15-20 minutes. DO NOT open the oven until at least 15 minutes have passed.

Berry pastry cream
10.5 oz milk
2 eggs
1 egg yolk
1 oz cornstarch
3 oz sugar
pinch salt
1/2 to 2/3 cup berry puree (I used frozen raspberries and blackberries)
1/8 tsp almond or vanilla extract

Heat the milk to simmering. Meanwhile, whisk together the eggs, cornstarch, sugar, and salt. When the milk is simmering, whisk a small amount into the egg mixture to temper, then a little bit more to ensure the egg mixture is warm. Whisk egg mixture into the remaining milk, and add the berry puree. Heat, whisking, until mixture is very thick and begins to bubble. When it does, cook for at least 1 minute, or until it no longer has the taste of raw cornstarch. Remove from the heat and whisk in the extract. Sieve into a container and press plastic wrap over the surface. Cool completely before using.

St. Germain Swiss meringue buttercream
2 egg whites
110 g, or about 1/2 cup, white sugar
1 stick butter, room temperature and cut into cubes.
pinch salt
2 or 3 teaspoons St. Germain, or to taste

Over a double boiler, whisk the egg whites and sugar until the mixture reaches 160F. Remove from the heat. Using a stand mixer, whisk the egg white/sugar mixture on medium speed until the mixture is cool and holds soft-to-medium peaks. Whisk in the butter, chunk by chunk. Keep whisking even if it looks curdled! When it has become homogenous and fluffy, add the pinch of salt and St. Germain, and continue to mix until optimal texture is achieved.