Everything You Should Know About Yams

Elazar Sontag wrote . . . . . . . . .

Knobbly and brown, with little, wispy, hair-like roots shooting off at random, yams aren’t the stateliest of foods. But if you get past their slightly odd appearance, you may very well fall in love. That is, if you even cross paths with a real yam. Chances are, unless you’re doing most of your grocery shopping at African, Caribbean, or Asian markets, or grew up eating and cooking these tubers, what you imagine when I say “yam” is actually just an orange sweet potato.

As I dug into just a little bit in my field guide to sweet potatoes—way too many puns here, I know—the practice of calling sweet potatoes yams started in the early 20th-century, when Southern farmers introduced softer-fleshed orange sweet potatoes to the American market. Farmers called orange tubers yams to differentiate them from the white-fleshed sweet potatoes people were already familiar with. The name stuck, and all these years later a good portion of us still couldn’t point out a real yam in a lineup. And that’s a shame, because their flavor and texture is completely unique, and they take well to all sorts of cooking methods and seasonings. A true yam is much starchier than a sweet potato, with a milder sweetness that becomes only slightly more pronounced when the root is cooked.

Orange sweet potatoes are often referred to as yams, though they come from an entirely different plant family.

Calling sweet potatoes yams in America wasn’t just a money-making ploy. For the first enslaved West Africans forcibly brought to America, sweet potatoes offered as close to a taste of home as they were going to get. Though sweeter and more watery when cooked, these orange sweet potatoes resembled the yams of Africa both in texture and appearance. “Slavers transporting captives from [West Africa] on the Middle Passage provisioned themselves with yams sufficient for the voyages,” wrote culinary historian Jessica B. Harris in an op-ed on the cultural significance of the yam. “But once ashore in more temperate America, the slaves found that the African tuber was unavailable, and thus substituted it with the sweet potato—leading to centuries of botanical and gastronomic confusion.”

Really, yams aren’t remotely similar to sweet potatoes. They belong to the Dioscoreaceae family of flowering plants, and grow in temperate and tropical climates, including in Africa, Asia, and the Caribbean. A yam is the extremely starchy tuber at the base of winding, bright-green herbaceous vines. While sweet potatoes generally don’t grow much longer or thicker than a baby’s forearm, yams can grow to be more than six feet long, and on rare occasions weigh in at over 150 pounds. That’s a very, very big tuber, and needless to say, not the sort of produce you’ll find squeezed into a grocery bin. There are more than 800 varieties of yams, and a majority of those are cultivated in Africa, with Nigerian farmers producing more than half of the world’s supply.

Some of the most common yam varieties you’ll come across include the popular white and yellow yams native to Africa, which resemble large potatoes in shape. In Asian markets you’ll find Chinese and Japanese yams, which have lighter-brown skin, and are cylindrical. Because yams are grown and eaten in different parts of the world, methods for cooking vary enormously from one kitchen to the next.

How to Buy and Cook Yams

Yams are very resilient, and they travel well. This means that, for the most part, you don’t have to worry about accidentally picking up a yam at the store that’s already spoiled—unlike the cursed-but-seemingly-fine avocado that is always rotten in the middle, no matter how beautiful its exterior is. If a yam’s skin is intact, and the root doesn’t have any soft or mushy spots, consider it good to go.

In Jamaica, you’ll find yams slowly roasting, skin still on, over an open fire. When they’re done, the interior can be easily pierced with a knife, but the skin isn’t burnt—an impressive feat. The meaty flesh of the yam, slightly smoky from the fire, is served alongside flavorful chunks of jerk pork, chicken, and other meats.

In Nigeria, where so many of the world’s yams are grown and the tuber is central to everyday life, they’re cooked into porridges, and cubed and stewed slowly with tomatoes, peanuts, greens, and spices. They’re also boiled then pounded into a version of fufu, one of West Africa’s most iconic dishes. The doughy, starchy mixture is perfect for absorbing sauce, and is eaten alongside more or less everything.

The yams eaten in the Caribbean and throughout Africa are larger and more bulbous than Chinese yams, which are also known as nagaimo in Japan. In China, the yams are sliced into rounds and boiled in soup until tender, stir-fried with fresh vegetables, blended into savory steamed cakes, and more. You can find wild Chinese yams pre-sliced and sun-dried in Chinese grocery stores. The dried yams are known as huai shan, and cooks reconstitute them in rich broths, simmering along with chicken, pork, goji berries, and dried jujubes.

Chinese and Chinese-American cooks like Lisa Lin, a food blogger and expert on Chinese cooking, also utilize a yam called yamaimo or East Asian mountain yam. This variety has a sticky, slightly slippery texture, and is often sliced finely and eaten raw. “One way to prepare the yams is to boil them in a soup,” says Lin. “My mom (the kitchen matriarch) says that the best ones for boiling are smaller ones or the ones that look very twisted and crooked—usually found in farmers markets. They don’t break down and turn to mush when they’re boiled.”

In Japan, among other applications, the starchy nagaimo and yamaimo yams are grated into the batter of okonomiyaki—chewy, savory pancakes showered in toppings and a mixture of a sweet and savory sauce and mayonnaise. The starchiness of the grated yams helps bind the pancake batter together, without adding too much moisture.

I’ve only touched on the very tip of the yam-shaped iceberg. There are hundreds of varieties of yams out there, used in more culturally diverse preparations than I could count. The knobbly root takes well to frying, braising, sautéing, boiling, roasting, and more. You just have to decide where to start.

Source: Serious Eats

Chinese Hakka Style Mini Pork Omelet Pot

Ingredients

150 g ground pork
3 eggs
400 g Lo Bok
1 bunch Chinese celery
1 cup chicken broth
2 slices ginger
1 tsp corn starch
1 tsp salt
1/2 tsp sugar
1 tsp light soy sauce
dash white pepper

Method

  1. Add 2 tablespoons of water to the cornstarch, let settled. Pour away the water leaving behind some wet starch.
  2. Add light soy sauce, sugar, white pepper and 1 tablespoon water to the ground pork and marinate for 15 minutes. Pan-fry pork and drain excess oil and water.
  3. Beat eggs, add wet starch and 1/2 teaspoon salt, mix well and run through a wire strainer.
  4. Heat 1 tablespoon oil in a wok under low medium heat, put in 1 tablespoon of stirred egg batter and let it form a round omelet at the center of the wok.
  5. Put 1 tablespoon ground pork onto one side of the omelet, shake the wok lightly to prevent omelet from sticking.
  6. Fold one side of the round omelet to the other side to form a half moon shape omelet. Repeat until all the egg batter are cooked.
  7. Peel the Lo Bok and cut into chunks and cut Chinese celery into sections.
  8. Heat 1 tablespoon oil in a clay pot and stir-fry the ginger slices briefly. Add Lo Bok, 1/2 teaspoon salt and chicken broth. Bring to a boil and cook for 10 minutes under low heat.
  9. Add Chinese celery and cook for another minute.
  10. Place omelets on top of Lo Bok and Chinese celery, and bring to a boil before serving.

Source: Hakka Cuisine

Real Texture for Lab-grown Meat

Lab-grown or cultured meat could revolutionize food production, providing a greener, more sustainable, more ethical alternative to large-scale meat production. But getting lab-grown meat from the petri dish to the dinner plate requires solving several major problems, including how to make large amounts of it and how to make it feel and taste more like real meat.

Now, researchers at the Harvard John A. Paulson School of Engineering and Applied Sciences (SEAS) have grown rabbit and cow muscle cells on edible gelatin scaffolds that mimic the texture and consistency of meat, demonstrating that realistic meat products may eventually be produced without the need to raise and slaughter animals.

The research is published in npj Science of Food.

Kit Parker, the Tarr Family Professor of Bioengineering and Applied Physics at SEAS and senior author of the study, began his foray into food after judging a competition show on the Food Network.

“The materials-science expertise of the chefs was impressive,” said Parker. “After discussions with them, I began to wonder if we could apply all that we knew about regenerative medicine to the design of synthetic foods. After all, everything we have learned about building organs and tissues for regenerative medicine applies to food: healthy cells and healthy scaffolds are the building substrates, the design rules are the same, and the goals are the same: human health. This is our first effort to bring hardcore engineering design and scalable manufacturing to the creation of food.”

Animal meat consists mostly of skeletal muscle (and fat tissue) which grows in long, thin fibers — as can be seen in the grain of a steak or when shredding pork or chicken. Reproducing these fibers is one of the biggest challenges in bioengineering meat.

“Muscle cells are adherent cell types, meaning they need something to hold onto as they grow,” said Luke MacQueen, first author of the study and a research associate at SEAS and the Wyss Institute for Bioinspired Engineering. “To grow muscle tissues that resembled meat, we needed to find a ‘scaffold’ material that was edible and allowed muscle cells to attach and grow in 3D. It was important to find an efficient way to produce large amounts of these scaffolds to justify their potential use in food production.”

To overcome these challenges, the researchers used a technique developed by Parker and his Disease Biophysics Group known as immersion Rotary Jet-Spinning (iRJS), which uses centrifugal force to spin long nanofibers of specific shapes and sizes. The team spun food-safe gelatin fibers to form the base for growing cells. The fibers mimic natural muscle tissue’s extracellular matrix — the glue that holds the tissue together and contributes to its texture.

The team seeded the fibers with rabbit and cow muscle cells, which anchored to the gelatin and grew in long, thin structures, similar to real meat. The researchers used mechanical testing to compare the texture of their lab-grown meat to real rabbit, bacon, beef tenderloin, prosciutto, and other meat products.

“When we analyzed the microstructure and texture, we found that, although the cultured and natural products had comparable texture, natural meat contained more muscle fibers, meaning they were more mature,” said MacQueen. “Muscle and fat cell maturation in vitro are still a really big challenge that will take a combination of advanced stem cell sources, serum-free culture media formulations, edible scaffolds such as ours, as well as advances in bioreactor culture methods to overcome.”

Still, this research shows that fully lab-grown meat is possible.

“Our methods are always improving and we have clear objectives because our design rules are informed by natural meats. Eventually, we think it may be possible to design meats with defined textures, tastes, and nutritional profiles — a bit like brewing,” said MacQueen.

“Moving forward, the goals are nutritional content, taste, texture, and affordable pricing. The long-range goal is reducing the environmental footprint of food,” said Parker.

“The development of cultured meat involves a number of technical challenges, including the formulation of a scaffold material that can successfully support cells and the development of cell lines that are amenable to cultivation for consumption at scale,” said Kate Krueger, research director at the cellular agriculture research institution New Harvest, who was not involved in the research. “The authors of this publication have developed scaffold materials that show great promise in these areas.”

Source: The Harvard Gazette

Windy, Humid Days Could Bring More Pain to Patients with Chronic Pain

Your great granddaddy may have been right about the weather worsening his arthritis.

People with chronic pain conditions are more likely to suffer pain on humid and windy days, according to a study that used smartphones to assess pain-weather connections.

“The results of this study could be important for patients in the future for two reasons,” said study leader Will Dixon, from the Center for Epidemiology Versus Arthritis, University of Manchester, in England.

“Given we can forecast the weather, it may be possible to develop a pain forecast knowing the relationship between weather and pain. This would allow people who suffer from chronic pain to plan their activities, completing harder tasks on days predicted to have lower levels of pain,” Dixon said in a university news release

“The dataset will also provide information to scientists interested in understanding the mechanisms of pain, which could ultimately open the door to new treatments,” Dixon added.

The study included more than 2,600 people across the United Kingdom with conditions such as arthritis, fibromyalgia, migraine and neuropathic pain.

The investigators used a smartphone app to record daily pain symptoms and their local weather was determined using location information from their smartphone’s GPS. Data was collected for about six months.

The participants were more likely to have pain on humid days than on dry days. Low pressure and higher wind speed were also associated with painful days, but to a lesser degree than humidity, the findings showed. However, the researchers could not prove a cause-and-effect relationship.

Overall, temperature did not appear to affect pain, but cold days that were also damp and windy could be more painful. There was no link between rain and pain.

The findings were published online in the journal NPJ Digital Medicine.

“The analysis showed that on damp and windy days with low pressure the chances of experiencing more pain, compared to an average day, was around 20%. This would mean that, if your chances of a painful day on an average weather day were 5 in 100, they would increase to 6 in 100 on a damp and windy day,” Dixon explained.

“Weather has been thought to affect symptoms in patients with arthritis since Hippocrates. Around three-quarters of people living with arthritis believe their pain is affected by the weather,” he said.

“Yet despite much research examining the existence and nature of this relationship, there remains no scientific consensus,” Dixon noted. “We hoped that smartphones would allow us to make greater progress by recruiting many more people, and tracking daily symptoms across seasons.”

Source: HealthDay

Study: Most Widely Prescribed Blood Pressure Drug Might Not be the Best Option

Millions of Americans take an ACE inhibitor to help curb their high blood pressure — in fact, these drugs are the most widely used antihypertensives in America.

However, a new international study of nearly 5 million patients is casting doubt on the notion that the drugs are as effective as another class of blood pressure medicines.

Common ACE inhibitors include drugs such as benazepril, captopril, enalapril, fosinopril and lisinopril, among others.

The new study should “help guide physicians in their clinical decision-making,” said study author Dr. George Hripcsak. He’s chair of biomedical informatics at Columbia University’s College of Physicians and Surgeons, in New York City.

American College of Cardiology and American Heart Association guidelines recommend starting blood pressure treatment with any drug from five different classes of medications. Those classes include: thiazide diuretics; ACE inhibitors; angiotensin II receptor blockers (ARBs); dihydropyridine calcium channel blockers and non-dihydropyridine calcium channel blockers.

To find out how often these medicines are prescribed, Hripcsak’s team tracked data on nearly 5 million patients across four countries — Germany, Japan, South Korea and the United States.

All of the patients began treatment for high blood pressure by using a single drug.

In nearly half (48% ) of cases, ACE inhibitors were the first drug prescribed, compared with 17% of patients who were first prescribed thiazide diuretics, the team found.

But the study suggests that ACE inhibitors might not always be the best choice.

Patients who were prescribed thiazide diuretics ended up having 15% fewer heart attacks, strokes and hospitalizations for heart failure, as well as lower rates of 19 side effects, compared to those who had been prescribed ACE inhibitors.

Crunching the numbers, the Columbia team calculated that about 3,100 major cardiovascular events among the patients who first took ACE inhibitors could have been prevented if they’d first been treated with a thiazide diuretic.

They reported their findings in The Lancet journal.

The researchers also found that another class of blood pressure meds, non-dihydropyridine calcium channel blockers, were less effective than all of the other first-line classes of blood pressure drugs.

Right now, there’s a real lack of research aimed at helping doctors choose which drug class a patient should start on, Hripcsak believes.

He noted that the current literature has data from randomized, controlled clinical trials that included a total of just 31,000 patients, and none of those patients were just beginning treatment for high blood pressure.

“Randomized clinical trials demonstrate a drug’s effectiveness and safety in a highly defined patient population,” Hripcsak explained in a university news release. “But they’re not good at making comparisons among multiple drug classes in a diverse group of patients that you would encounter in the real world.”

With the new study, Hripcsak believes that “we have found a way to fill in the gaps left by randomized, controlled trials.

Two cardiologists who weren’t involved in the new study took different stances on the results — suggesting that debate on this topic is far from over.

Dr. Satjit Bhusri said the study “is statistically very powerful and can have profound changes in medical practice.” But he added that decisions around which anti-hypertensive drug to choose should still be made on a case-by-case basis.

“I would suggest that the choice of first-line blood pressure therapy be specific to the patient, especially in those with heart disease or at an elevated risk of heart disease.,” Bhusri advised. But, for patients “treated for high blood pressure without an elevated cardiac risk, thiazide medication should be the first-line [choice],” he said.

However, cardiologist Dr. Benjamin Hirsh took issue with the Columbia study’s methodology.

The researchers’ conclusion that “use of thiazide diuretics over ACE inhibitors causes ‘15% fewer cardiovascular effects’ is a conclusion that is highly subject to bias,” he noted.

“ACE Inhibitors are used to treat patients with higher cardiovascular risk, such as those with advanced heart failure and kidney disease,” Hirsh explained.”So, these patients are at higher risk for heart disease in general.”

According to Hirsh, it stands to reason that patients on ACE inhibitors would have worse outcomes than those on thiazide diuretics, because they were sicker to begin with.

And he noted that “thiazide diuretics also must be used carefully with other drugs.” Those include newer diabetes medications such as Jardiance, because the concurrent use of a thiazide diuretic might trigger too-low blood pressure, Hirsh explained.

Source: HealthDay


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