Monthly Archives: February 2014

Writing prompt: giant sheep

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Time: 7 minutes. Click here to go to my list of prompts.

“Giant sheep” (This prompt is loosely inspired by Norstrilia by Cordwainer Smith, which involves ranching gigantic sheep that produce an immortality serum. If you are looking for weird sci-fi, give in it a try)

John’s sheep Dolly stood with effort. She had eaten everything on this patch of the ranch, and regrettably had to drag herself to another patch. This part always worried John. Although Dolly’s bones were engineered to include carbon nanofibers, her tremendous weight still caused fractures sometimes. A few generations ago, the sheep were only 50 feet tall. Now they were 100 feet tall, and maybe that was just too tall.

Dolly sensed the danger, too, and she walked gently, testing each patch of ground before placing her weight more firmly. John stayed well back from her path. She had lost her balance before. Other ranchers had died in this way.

Dolly set another foot down. John heard a cracking sound. “Oh no, oh no, oh no!” He shouted. He ran from Dolly. She gurgled in surprise as a sinkhole opened under her hoof. She tumbled to the ground. Her eyes were wide and she bleated deafeningly. The fall must have injured her.

John sighed. Ohio simply wasn’t Norstrilia, and this stupid form of husbandry should have stayed on that god forsaken rock. He ought to switch to giant chickens.

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Fun science: the smell of lavender

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This weekend, I visited a lavender farm, and thus smelled a lot of lavender. The sense of smell is really an amazing thing. Our vision processes light waves, our hearing processes sound waves– but smell processes many kinds of molecules at concentrations down to parts per billion. We tend to think of smell as a less important sense, but from a scientific standpoint, it’s amazing.

How does smell work?

The short answer is, we don’t fully know. We know receptors recognize different parts of molecules like ketones, alcohols and aldehydes. We don’t know how the brain assembles all the information from the various receptors. Some studies suggest that groups of neurons synchronize in different ways for different scents, while other studies suggest that the locations of receptors that fire create a spatial pattern for each smell. You can find further reading here, but fair warning, it’s tough material.

How sensitive is smell?

We can detect methyl mercaptan, the scent added to natural gas so that we can smell leaks (also the smell of asparagus pee!), down to parts per billion (ppb).

We can also tell the difference between very similar compounds. Linalool, the primary component of lavender oil, exists in two configurations called enantiomers. Both contain the same elements linked in the same way, but the two are mirror images. The left-handed linalool is the primary component of coriander seed and sweet orange flowers. The right-handed linalool is the primary component of lavender and sweet basil. (L)-linalool is sweeter and detectable to 7.4 ppb while (R)-linalool is woodier and detectable to 0.8 ppb.

Left:Left-handed linalool, the primary smell of coriander seed. Right: right-handed linalool, the primary smell of lavender oil. Image from Wikimedia commons.

Smell and Emotions

Studies suggest that the smell of lavender relieves anxiety and can promote sleep. Smell is strongly tied to emotions; the same parts of the brain that process smell store emotional memories.

I wonder if this connection is partially why we discount smell; smell is at its basic core tied to emotions rather than logic. It’s hard to put a smell into words, and science understands our others senses far better. I stood in the room full of lavender, remembering my last visit to a lavender farm with my family, and thought about how amazingly complex our response to little molecules can be.

Food and science: sous vide or water bath cooking

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In sous vide cooking, food is cooked in a water-bath at low temperatures (130-150 F) for longer times. Food cooked sous vide can be radically different in texture and taste than food cooked by more traditional methods. Even better, sous vide cooking is really, really easy.

What is sous vide?

In sous vide cooking, food in plastic bags is placed in a fixed-temperature water bath. The water bath temperature is held most easily by a digital controller. Some people build their own systems on the cheap. I bought this one, which in my opinion is worth every bit of $200.

As I discussed last week, bacteria die above 125 F. Consequently, food can be cooked at any temperature above 125 F (the closer to 125 F, the longer required for sanitation). This means a steak can be cooked to 130 F and be rare throughout, but also safe. For a 1 inch thick steak, this takes about an hour.

Why is it different?

Like a crock pot, sous vide cooking can be used to make tough cuts of meat extremely tender. Unlike a crock pot, the user has precise control over the set temperature, and the food is isolated from the water in which it cooks. This means that sous vide food isn’t soggy like slow cooker food so often is.

When we cook meat, the textural and color changes we observe are due to changes in the protein of the meat. Different proteins break down at different temperatures. The controller I use (linked above) allows control down to 0.1 C or 0.5 F. With such fine control, the cook can choose the exact temperature at which they wish to cook, and thus the effect they’d like to have on the protein. Poached eggs best demonstrate the results of this control. The proteins in the yolk coagulate at lower temperatures than the proteins in the white. By changing the cooking temperature only slightly, the cook can dramatically change the textures in the poached egg. This is called the perfect egg–at the link you can see eggs cooked to a variety of temperatures.

The set-up

For my set-up, the only major cost was the controller. I clamp it to the edge of a 8 qt pot (bigger would be better, but it’s what I had). Many people vacuum-seal their food before cooking, but the sealing system is an additional cost. I put my food in ziplock bags (glad bags are reported to be BPA-free). Then I add a little oil, squeeze the air out, and seal. To start cooking, I wait for the water in the pot to heat up and I clip the bag to the edge of the pot with a clothes pin.

Recipes and further reading

  • Citizen sous vide: an excellent general guide, with links to recipes and product reviews. Recipes are sorted by meat and cut.
  • Douglas Baldwin’s A Practical Guide to Sous Vide: a more technical discussion of sous vide with straightforward and instructive videos. This guide really explains the motivations of cooking sous vide.
  • Recipe for tri-tip steak: this recipe suggests cooking a tri-tip at 130 F for 6 hours, results shown below. You can see the meat is still pink in the middle. Cooking for six hours allowed it to tenderize, and all I had to do was cut up some meat and stick it in a bag. Very easy and delicious.

  • Tri-tip steak cooked sous vide.

    Tri-tip steak cooked sous vide.

Writing prompt: the spongy place in the yard

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Time: 7 minutes. Click here to go to my list of prompts.

“The spongy place in the yard” (As a kid in the northeast, this happened in my backyard. I thought there was something under there, which made a perfect launching point for a prompt.)

Every spring, after the snow melts, the backyard gets spongy. I always knew why, and though I told mom, she laughed and smiled in that patronizing way. I knew there was something underground. The ground just sagged too much, the way the ceiling sagged and my grandmother’s abandoned childhood home. I could tell by the way it looked that it was a sagging ceiling too. I was just seeing it from above.

Then I noticed that the neighbor spends a lot of time in her shed. Hours. She must be about two hundred, hunched and always walking with a hand against the small of her back. Summer or winter, she walks with a throw wrapped tightly over her shoulders.

So last night, I went into her shed. Sure enough, under a sheet of plywood, I found a staircase downward. I turned on my flashlight, and I went down the winding stairs. There must have been fifty, I lost count. At the end of the staircase, I found myself in a huge earthen room, taller than any room in my house. And on the ceiling, they hung, dozens of little people like my neighbor. They were all wrapped up in throws like the woman. Then they noticed me, and I discovered they weren’t throws. They were wings. And they were flying after me.

I panicked, and I ran down a corridor into the darkness. I dropped my flashlight, but I kept running, because duh. I hear the rustle of their wings in the darkness, searching, like the sound of a sheet being snapped again and again.

 

Thoughts of warmer places

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Here in the mid Atlantic, last week’s snow melts and compacts on the ground. It looks great when it falls, but it grows messy and treacherous quickly. But it is February, and the days grow longer. Soon they must grow warmer too. But in the meantime, this time of year, I like to fondly review photos from warmer places.

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Old Anglican church on St. Kitts.

Old Anglican church on St. Kitts.

St. Kitts, looking toward Nevis.

St. Kitts, looking toward Nevis.

Jungle in St. Lucia

Jungle in St. Lucia

Food and science: when is food safe?

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The milk we get at the store is pasteurized, and we all know that chicken must reach 165 F and pork must reach 145 F. What is the source of these numbers, and what is their purpose?

Raw foods like meat and dairy contain a certain number of pathogens that can make us sick. These pathogens die when heated above about 125 F. So why are cooking temperatures much higher than 125 F? The recommended cooking temperatures are the temperatures your food must reach in order for a large enough portion of the bacteria to die nearly instantaneously. At 140 F, the salmonella in ground beef is reduced by a factor of ten every 5.48 minutes. Salmonella must be reduced by a factor of ten million to one, so you would have to hold this temperature for a while. At 150 F, the salmonella is reduced by a factor of ten every 0.55 minutes, so this is quite a bit faster. At 160 F, the bacteria reduces fast enough that by the time you’ve measured it, enough time has passed. The process of “sous vide” cooking uses lower temperatures applied steadily for long times to cook food. I will discuss this excellent cooking method in a future post.

The process of making food safe by reducing the bacteria is called pasteurization, which you may be more familiar with from the dairy aisle than meat, but the concept is the same. Also in dairy, the time for pasteurization depends upon the temperature. Pasteurized milk is heated to 162 F for at least 15 seconds while ultra-pasteurized milk is heated to 280 F for 1-2 seconds. Eggs are not usually pasteurized, but they can be when heated to 130 F for about an hour.

Douglas Baldwin’s section on food safety in his online guide to sous vide is the source of much of the information I present here. It is full of scientific citations, but is very readable, and I highly recommend it as further reading. Happy Valentine’s Day!

Writing prompt: The special box of chocolates

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Time: 7 minutes. Click here to go to my list of prompts.

“The special box of chocolates” (author’s note: I am apparently a terrible Valentine. This was the less horrifying of the two prompts I wrote today. You were warned.)

We’ve come a long way with chocolates, I mused to myself, leaving the confectionary with a gleaming heart-shaped box full of truffles. I’d had the old versions, with just sugar and caffeine as their chemicals of action. They tasted nice, but it was a letdown compared to the modern thrills. I pulled out the guide on the walk home. The one with the ripple caused increased *ahem* blood flow, the one with the white stripe caused relaxation, the triangular one caused a sort of numbness that increased stamina… my favorite was certainly the square dark chocolate one that sort of made you feel like the other person, especially if they had one too. I slipped the guide back into the box, and grinned at the knowing leers as I walked.

My husband’s eyes flickered when I arrived home. “Ha, really John?”

“I get it every year, I know,” I said sheepishly. “But I so look forward to it.”

“I do too,” he said, wrapping his arms around me. For a bit, we needed no chemical excitement at all.

I stumbled out of the bedroom, feeling pleased with myself. But then I saw the beautiful box of chocolates, chewed and gnarled. The dog. Oh my god, he could be poisoned!

The dog, a great, powerful bulldog, came around the corner, and then I realized that poisoning might be the least of my issues. He snorted, and he looked me in the eye. I dashed out the door, half-naked, into February.

Fun science: how does figure skating work?

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How does figure skating work? In short, we don’t fully know. You may have learned in science class that the pressure of the blade causes the ice to melt. Water does have the unusual property that solid ice is less dense than liquid water, and ice will melt under sufficient pressure. The thing is, the weight of a human body on an ice skate isn’t enough pressure to induce that melting.

Phase diagram for water. At normal atmospheric pressure, water freezes (to ice I, or normal ice) at 32 F or 273 K. At higher pressures, the freezing point is suppressed, as shown by the solid black line between the blue and white regions at the bottom. (Figure credit, Wikimedia)

So, if not the weight of the skater, what allows the blade to slide along? Well, there is a layer of liquid at the interface of the blade which allows the skater to glide. Denizens of very cold climates know that at sufficiently cold temperatures, skates do start sticking and catching on the ice (source: my mom’s many winters in Wisconsin, and science). Our best guess right now is that the surface properties of ice differ from the properties of the bulk. Perhaps at the surface of ice, the pressure *is* sufficient to cause melting (at temperatures near enough to freezing).

The difference between bulk properties (the properties of a big chunk of something) and surface and scale-related properties is increasingly studied. Nano-scale gold exhibits a wide variety of properties depending upon particle size, as you can see in the image below. Such colloidal gold is used in a variety of medical applications such as tumor detection and drug delivery.

Solution colors change as the gold particle sizes change. (image source Wikimedia).

When things like water and figure skating are still mysterious, who says science doesn’t leave room for wonder? Given the relatively few forces interacting in such systems, I find the richness of variation we observe entrancing. This Olympics, I’ll watch the athletes skate and consider the angstrom-scale world on which our lives glide.

Why I cook: food and science series

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I cook a lot. I cook because it’s cheaper, but mostly I cook because I am absurdly lactose-intolerant, with a generally fussy tummy. As a kid, cooking seemed like something girly and irrelevant; food simply appeared. Now I see that eating is something we do every day and it can be either drudgery or exquisite.

This post is the first of a series I will post each Friday. Other posts will talk about specifics: science, recipes, and methods. Today I will talk more about how cooking became something I spend time on, and why cooking matters.

In college, I picked up some kind of food poisoning, probably on dorm food. I started to get sick a lot. I lost weight. I drank bulk-up drinks like body builders do. I became sensitive to milk products; I switched to lactose-free milk, and started drinking whole milk. I couldn’t move after meals, or else I’d get sick. If I ate even a bite too much, I got sick. If I got too hungry, I got sick. My lunches were often half a pizza slice. I bottomed out with a BMI below 18. Doctors seemed disinterested my inability to keep food, but they couldn’t explain the weight loss.

Finally, I started taking probiotics, which seemed to help. Now, seven years after my minimum weight, I’m at my high school weight, with gain more of a concern than loss. I cook most meals for myself, where I have control over my intake. Eating out with others isn’t easy, because I must be picky and inflexible about where and when I eat. I can’t wing it. If I deviate from the rules too much, I will get sick, which directly affects me for up to a day, and destabilizes me for the future. It’s manageable; some people with IBS get sick a dozen times a day, and digestive illnesses like Crohn’s disease can be life threatening.

The gut is understood very poorly, despite its importance. The enteric nervous system, or gut brain, is the site of 90% of serotonin and 50% of dopamine. With my ups and downs, I know well the relationship between gut health and mood. The digestive system is second in neurons only to the brain, and contains more neurons than the spinal cord. It is the engine of our body, and it functions in tandem with more bacteria than there are stars in the galaxy. Yet Americans spend the least time cooking of any country on Earth.

Loads of scientific evidence and my own personal evidence shows that a happy tummy goes a long ways towards a happy person, even in cases less extreme than mine. Good food can be a blissful experience, and in these posts I’ll talk about some methods toward good food. I don’t believe in diets or supplements or shortcuts, just making food that works. Good food can be made in a small kitchen on a limited budget with limited time. The primary ingredient is our own interest and curiosity, which I intend to share here.

SONY DSCMy newly reorganized office. The flat storage cabinet in the corner is a new and much-treasured addition. Now I can organize the flat stuff way better and also keep it safely away from cat feet (they have a sixth sense for stretching on the most expensive piece of paper). Great things are going to happen here. Too exciting not to share.