What a Pressure Cooker Does Best

Tim Chin wrote . . . . . . . . .

Pressure cookers are powerhouses of culinary innovation. Though they have a rich history and relatively straightforward scientific explanation, confusion about how they work and what they’re good for abounds. I’ve already answered the question of how pressure cookers work, including how they’re designed, the important safety features included in newer models, and the intimate relationship between pressure and temperature. The long and short of it is that pressure cookers allow you cook your food at higher temperatures, which in turn speeds up your cooking.

But a pressure cooker isn’t just a tool for cooking things faster. In fact, the high temperature and high pressure inside a sealed pressure cooker are ideally suited for a number of culinary applications. Let’s break it down.

Extract Gelatin and Flavor for the Best Stocks Ever

The pressure cooker is the MVP of making stocks. Take Daniel’s pressure cooker chicken stock, for example. Making chicken stock on your stovetop requires at least a couple of hours of careful simmering. With a pressure cooker, you can have a richer, more intense stock in under an hour.

There are two reasons for this. First, the higher temperature extracts flavor from meat and vegetables quickly. Second, since collagen in the presence of water begins breaking down into gelatin starting at temperatures as low as 160°F (70°C)—and accelerates as temperature increases—the high temperature in a pressure cooker converts the collagen in connective tissues to gelatin in a flash. Gelatin is the key to a rich stock with a thicker body and velvety texture.

There’s another advantage to cooking stock in a pressure cooker: Because you’re cooking the chicken stock at high pressure, the contents never really come to a boil, so the cooking is gentle. (The contents never boil as long as (a) you don’t allow a pressure cooker to over-pressurize and vent, and (b) you don’t employ the quick-release method to depressurize the pot.) This stillness produces a clearer, cleaner stock, one that resembles consommé, where an egg raft is used to separate out the denatured proteins and impurities that typically make stock cloudy when agitated or mixed.

Tenderize Tough Cuts of Meat on the Fly

That same collagen-rendering heat is what makes the process for Kenji’s recipe for pressure cooker pork chile verde so simple and fast. The tough pork shoulder meat becomes meltingly tender in just 45 minutes, as opposed to the hours it would take to get it tender with simmering. The same principle can be applied to cooking other tough cuts like beef chuck, pork belly, or even oxtails.

Cooking Rice, Grains, and Beans

Rice is finicky, and it takes a while to cook. The grains have to absorb water, and heat is required to break down starches to soften those grains. If you don’t want mush, you have to pay close attention to the ratio of water to rice, regulate heat, and account for evaporation, depending on the cooking vessel. A pressure cooker removes many of those variables and speeds up the process considerably. For instance, Kenji’s pressure cooker mushroom risotto only takes five minutes to cook the rice to a perfect al dente, compared to the 45-plus minutes it takes following a more conventional method. And, because there’s no evaporation, you can dial in the amount of cooking liquid (and you can use far less), resulting in a consistent texture, every time. There’s virtually no guessing and no eyeballing involved. Finally, the absence of any agitation in the pressure cooker provides a gentle, still cooking medium for the rice, which helps to keep individual grains intact and separate.

The same principle applies to other grains as well, although the payoff isn’t as dramatic. For instance, wheat berries take a notoriously long time to cook using conventional methods—upwards of an hour and a half on the stovetop. Some sources say that a pressure cooker cuts that time by more than fifty percent, to 40 minutes. Barley can go from 50 minutes to less than twenty, and farro can be cooked in less than eight minutes. The catch? Daniel found that using a pressure cooker on whole grains like farro, wheat berries, and whole-grain spelt did cut down on cooking time. But after factoring in the time it takes to pressurize and depressurize a pressure cooker, he found you only really save about 10 minutes compared to a more conventional method.

Grains not your thing? A pressure cooker slaps with beans and legumes, too. Kenji’s quick and easy pressure cooker black beans recipe cuts the cooking time from three hours to 40 minutes—no pre-soaking and no baking soda required.

For both grains and beans, one disadvantage to pressure cooking is that there’s no way to monitor the contents once things are cooking. You can’t just quickly open up the pot without depressurizing and re-pressurizing again. Instead, cooks must rely on recommended cooking times. If foods don’t cook in the recommended time, you’ll have to bring the pot back up to full pressure to keep cooking.

Pressure Caramelization: Wet Maillard Reactions

Under certain conditions, a pressure cooker can actually speed up Maillard reactions that otherwise wouldn’t happen at normal atmospheric pressure and temperature.

Maillard reactions are the cascade of small chemical reactions, catalyzed by heat, that occur between proteins (technically, the amino acids that make up proteins) and sugars, which produce new flavors, aromas, and colors. Most of the time, these reactions require heat in excess of 300°F (150°C) to happen quickly and readily. But there’s evidence that Maillard browning can happen at even lower temperatures, given enough time. Anecdotally, we see this happen when a chicken stock darkens as it cooks—and becomes even darker still as you reduce it to a demi-glace consistency over the course of a few hours, which is probably both a function of concentration and Maillard browning.

Why would you want to go to the trouble of making Maillard browning happen in a pressure cooker? In general, Maillard reactions occur alongside dehydration. In an open system (like an oven) with free evaporation, heat drives off surface moisture and allows temperatures to exceed the boiling point, which facilitates Maillard browning. Cooking in this way leads to crisping and crunching—and even burning if taken to an extreme. In a pressure cooker, there is zero evaporation, so you can have Maillard browning throughout, without drying out surfaces first. The resulting browning is also distributed more evenly throughout the food, not just on the surface.

To speed up Maillard browning in a pressure cooker, it’s often necessary to raise the pH to create a basic or alkaline environment, which increases the speed of reactions by making amino acids more reactive with sugars. In fact, “pressure-caramelization” (admittedly a bit of a misnomer, since it’s really a Maillard reaction at work, not caramelization, which is a different reaction altogether) is a technique popularized by Modernist Cuisine: By adding baking soda to a high-sugar vegetable or fruit and cooking under pressure, the food undergoes significant Maillard browning. Kenji takes advantage of this technique for his pressure caramelized onions. You still won’t get true caramelization (which is why Kenji opts for a quick post-pressure cook), but it’s a quick way to get that initial browning and flavor at a relatively lower temperature.

You can “pressure-caramelize” almost any fruit or vegetable, although don’t expect them all to be winners. Sweet potatoes and carrots work beautifully, but Daniel doesn’t really recommend pressure-cooking butternut squash, which somehow tastes like pretzels. If you’re a fan of banana bread, I highly recommend pressure-caramelizing bananas for an added layer of intense, butterscotch-like flavor.

Canning and Preservation

Let’s not forget one of the original uses for pressure cooking in general. High pressure and high temperature are ideal for forcing out unwanted oxygen and killing pesky microbial baddies when canning foods. Pressure canning is well suited for foods that are low-acid (higher than 4.6 on the pH scale), or require high heat to kill anaerobic microbes such as Clostridium botulinum. To properly do so, you should invest in a pressure canner, which features a gauge that allows you to more accurately track pressure.

If you want a more comprehensive (and wonderful) explanation of pressure canning and preservation, Christina Ward’s guide to the science of canning is all the nerding out you could ask for.

The Limit Does Not Exist

Is there anything a pressure cooker can’t do? We have yet to explore some lesser-known applications. KFC is famous for popularizing industrial pressure-fried chicken. Could you do it at home? Probably. But should you? Probably not, unless you love ruining kitchen equipment and dealing with blazing hot oil. Then there’s pressure cooked seeds: Dishes like sunflower seed “risotto” or pumpkin seed mole, which use the pressure cooker to produce otherwise unachievable textures. I’m probably missing several more techniques, but I’ll leave that to the geeks out there.

Peer Pressure

Hopefully, you’re now convinced that a pressure cooker is a useful—essential, even—tool that you should have in your kitchen. Armed with all this knowledge and pressurized power, I encourage you to cut loose and pressure-cook everything in sight. And if you’re ever in doubt, keep this in mind: If something usually takes a long time to cook, doesn’t need a ton of dry heat, and has a good amount of moisture when cooked, it’ll probably do great in a pressure cooker.

Source: Serious Eats

Scrambled Egg, Roast Tomatoes and Prosciutto with Mushroom Puree

Ingredients

1/2 oz dried porcini mushrooms (or 1 oz fresh porcini mushrooms, finely chopped)
8 medium vine tomatoes
2 tablespoons olive oil
3 tablespoons butter
1 garlic clove, crushed
1 tablespoon creme fraiche (or sour cream)
a big pinch of freshly snipped chives
4 eggs
scant 1/4 cup whole milk
6 slices prosciutto
sea salt and black pepper, to season

Method

  1. Preheat the oven to 190°C (375°F).
  2. First, prepare the mushroom puree. If you’re using dried porcini mushrooms, soak them in boiling water for about 20 minutes, then drain and finely chop.
  3. While the mushrooms are soaking, prepare the roast tomatoes. Keep the tomatoes on the vine and put them in an ovenproof dish, then drizzle over the olive oil. Season with salt and pepper. Roast in the preheated oven for 20-25 minutes, until they are soft and start to brown.
  4. Melt 1 tablespoon of the butter in a frying pan/skillet, then add the garlic and soaked or fresh porcini mushrooms. Mix in the creme fraiche (or sour cream) and stir well. Remove from the heat and keep hot. Sprinkle snipped chives on the top.
  5. A few minutes before you are ready to serve, make the scrambled eggs.
  6. In a bowl, beat the eggs, milk and a bit of pepper together really well.
  7. Melt the remaining 2 tablespoons butter in a separate frying pan/skillet and pour in the egg mixture, stirring constantly to keep it from setting or sticking. Continue cooking and stirring, until the eggs are scrambled to your liking.
  8. You can serve the prosciutto slices as they are, or, lay the slices in the pan that you used for the mushroom puree and cook for just a couple of minutes on each side, turning once, so that they start to crisp and soak up some of the flavour of the mushrooms.
  9. Serve the scrambled eggs immediately with the mushroom puree, roast tomatoes and prosciutto.

Makes 2 servings.

Source: 100 Ways with Eggs

In Pictures: Easter Eggs

New Blood Test Can Detect Wide Range of Cancers

In a study involving thousands of participants, a new blood test detected more than 50 types of cancer as well as their location within the body with a high degree of accuracy, according to an international team of researchers led by Dana-Farber Cancer Institute and the Mayo Clinic.

The results, published online today by the Annals of Oncology, indicate that the test – which identified some particularly dangerous cancers that lack standard approaches to screening – can play a key role in early detection of cancer. Early detection can often be critical to successful treatment.

Developed by GRAIL, Inc., of Menlo Park, Calif., the test uses next-generation sequencing to analyze the arrangement of chemical units called methyl groups on the DNA of cancer cells. Adhering to specific sections of DNA, methyl groups help control whether genes are active or inactive. In cancer cells, the placement of methyl groups, or methylation pattern, is often markedly different from that of normal cells – to the extent that abnormal methylation patterns are even more characteristic of cancer cells than genetic mutations are. When tumor cells die, their DNA, with methyl groups firmly attached, empties into the blood, where it can be analyzed by the new test.

“Our previous work indicated that methylation-based tests outperform traditional DNA-sequencing approaches to detecting multiple forms of cancer in blood samples,” said Dana-Farber’s Geoffrey Oxnard, MD, co-lead author of the study with Minetta Liu, MD, of the Mayo Clinic. “The results of this study suggest that such assays could be a feasible way of screening people for a wide variety of cancers.”

In the study, investigators used the test to analyze cell-free DNA (DNA from normal and cancerous cells that had entered the bloodstream upon the cells’ death) in 6,689 blood samples, including 2,482 from people diagnosed with cancer and 4,207 from people without cancer. The samples from patients with cancer represented more than 50 cancer types, including breast, colorectal, esophageal, gallbladder, bladder, gastric, ovarian, head and neck, lung, lymphoid leukemia, multiple myeloma, and pancreatic cancer.

The overall specificity of the test was 99.3%, meaning that only 0.7% of the results incorrectly indicated that cancer was present. The sensitivity of the assay for 12 cancers that account for nearly two-thirds of U.S. cancer deaths was 67.3%, meaning the test could find the cancer two-thirds of the time but a third of the time the test returned a negative result. Within this group, the sensitivity was 39% for patients with stage I cancer, 69% for those with stage II, 83% for those with stage III, and 92% for those with stage IV. The stage I-III sensitivity across all 50 cancer types was 43.9%. When cancer was detected, the test correctly identified the organ or tissue where the cancer originated in more than 90% of cases – critical information for determining how the disease is diagnosed and managed.

“Our results show that this approach to testing cell-free DNA in blood can detect a broad range of cancer types at virtually any stage of the disease, with specificity and sensitivity approaching the level needed for population-level screening,” Oxnard obser

Source: Dana-Faber Cancer Institute

Being Chained to Your Desk Might Harm Your Thyroid

Could long hours at the office put you at risk for hypothyroidism?

New research suggests it’s possible: Hypothyroidism (an underactive thyroid) was more than twice as common in adults who worked 53 to 83 hours a week as in those who worked 36 to 42 hours a week (3.5% vs. 1.4%).

Hypothyroidism can cause tiredness, depression, feeling cold and weight gain, and it’s also a risk factor for heart disease and diabetes.

In this study, researchers analyzed data from 2,160 adult full-time workers in South Korea. Records of blood work done on the workers allowed researchers to identify hypothyroidism.

For each 10-hour increase in the work week, people who worked longer hours had a higher risk of hypothyroidism than those who worked 10 hours less, according to the study published March 31 in a special supplemental section of the Journal of the Endocrine Society.

Hypothyroidism affects women more often than men, but the researchers found that long working hours was associated with an increased risk of hypothyroidism regardless of the workers’ sex or socioeconomic status.

Further research is needed to determine whether long working hours actually cause hypothyroidism, said study principal investigator Dr. Young Ki Lee, from the National Cancer Center in Goyang-si, South Korea.

“If a causal relationship is established, it can be the basis for recommending a reduction in working hours to improve thyroid function among overworked individuals with hypothyroidism,” Lee said in a journal news release.

“Additionally, screening for hypothyroidism could be easily integrated into workers’ health screening programs using simple laboratory tests,” he noted.

“Overwork is a prevalent problem threatening the health and safety of workers worldwide,” Lee said. “To our knowledge, this study is the first to show that long working hours are associated with hypothyroidism.” The study only found associations, not a cause-and-effect link.

In 2018, South Korea passed a law restricting the maximum number of working hours from 68 to 52 a week.

“If long working hours really cause hypothyroidism, the prevalence of hypothyroidism in Korea might decrease slightly as the working hours decrease,” Lee said.

Source: HealthDay


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