Tuesday, November 21, 2017

Thanksgiving Part 4 — Squashes and Pumpkin Pie

A while back, before I retired from the Division of Nutritional Sciences at Cornell University, I helped write answer for a nutrition Q&A website that we called Nutriquest. Was looking over my files and found a four-part series I wrote for Thanksgiving. Here is the fourth and final part, lightly edited.  

THANKSGIVING - PART IV

Pumpkins and squash are two Native American foods that grace our Thanksgiving table. Pumpkins come from Mexico...and squash? Read on and find out!

Pumpkins and squash -- another delicious gift from Native American agriculture.

While squashes of the genus Curcubita can be found everywhere, the orange version, the pumpkin, is one of the many culinary gifts that Mexico has given to us.

Green and yellow squashes (from the Narragansett word "asquutasquash," and not from the word meaning to flatten -- squashes are hardly flat!) were originally cultivated in North America before the introduction of the Mexican imports, pumpkin and corn. The squash was one of group of seven plants which were domesticated by the Native North Americans around 2000BC, or perhaps even earlier. Genetic studies have revealed that the acorn and butternut squashes that we eat now are descended from the wild gourds that are plentiful weed plants in the Plains states, while the pumpkin comes from a different, Mexican lineage.

To learn more about the archeological hunt for the ancestors of these squashes, and the development of agriculture in North America, visit https://www.thoughtco.com/domestication-history-of-the-squash-plant-172698, and take a look at the sources at the end of the page. This page https://www.thoughtco.com/eastern-north-american-neolithic-171866 details more about the Eastern North American neolithic food domestication process.

The squash blossom is one of the few edible flowers -- to find out more consult the website: https://whatscookingamerica.net/EdibleFlowers/EdibleFlowersMain.htm. The warnings on that page are important!

Zucchini flower by Sarah Stierch (CC BY 4.0) — https://commons.wikimedia.org/wiki/File:Zucchini_flowers_-_stierch.jpg

Pumpkin and other thick skinned squashes are also called winter squashes, because their thick skins allow them to resist the cold, so they can grow in winter. Summer squashes, like zucchini, have thin skins, and grow in the summer—and they are not picky about growing conditions, as anyone who has had more than enough of them at the end of summer knows!

Do pumpkins and squash have nutritional value?

Members of the Curcubita family are low in fat, high in carbohydrates and rich in beta-carotene, which gives may of hem their orange color. The body transforms beta-carotene at a rate that corresponds to the body's needs. Incidentally, when I was working as a pediatrician, parents would come to me with babies who were bright orange. Turns out that they were offering their babies orange squashes as their first solid food. Beta-carotene had accumulated in their skin!

The nutritional value of beta-carotene has been the subject of much debate among scientists—you certainly need beta-carotene, but how much? Scientists originally suggested that large amounts of beta-carotene might be effective in preventing cancers because of its anti-oxidant properties. This suggestion led to three controlled studies, which showed either no effect, or in the case of smokers, an increase in the development of lung cancer. Subjects in these studies received large amounts of beta-carotene in a supplement—much more than you would get in a slice of pumpkin pie. See: Incidence of Cancer and Mortality Following α-Tocopherol and β-Carotene Supplementation—A Postintervention Follow-up. JAMA. 2003;290(4):476–485. doi:10.1001/jama.290.4.476.

So I like pumpkins and squash -- now how do I cook the them?

Just as there are for succotash and turkey, there are many, many recipes for the squashes on the web, which you can find using your favorite search engine.

Pumpkin and squash can be made into soup; they can be added to a number of different main and side-dishes, and baked into bread, and then of course there is pumpkin pie.

I've made mine with a graham cracker crust as well as with a regular pie crust, and once I even made one with a chocolate cookie crust—it was deee-licious! [Chocolate goes well with the hot-receptor-activating spices in the custard.]

One tradition my family and I have enjoyed is the addition of raisins to the pumpkin custard in the pie, but if you do add raisins, be sure to plump them up. My personal preference is to plump them up in a cream sherry—just soak them overnight in the sherry, drain and add to the custard mix. Then when you eat the pie you get little bursts of sherry flavor with each bite—a simple version of molecular gastronomy's "pearls."

Oh, and one year we had a guest who was lactose intolerant—lactose-free milk made for an excellent pie filling, although the result was somewhat lighter in color than usual, because part of the brown color of the pie filling comes from the reaction of the lactose with the protein in the milk and and eggs as the pie cooks.

So enjoy your Thanksgiving foods; if at all possible, share your good fortune with others; and most of all, to all of you from all of us:

HAVE A HAPPY THANKSGIVING!

Thanksgiving Part 3 — Turkey

A while back, before I retired from the Division of Nutritional Sciences at Cornell University, I helped write answer for a nutrition Q&A website that we called Nutriquest. Was looking over my files and found a four-part series I wrote for Thanksgiving. Here is the third part, lightly edited.  The final part will be posted tomorrow.

  The turkey—shown here shoving the bald eagle off our national shield—is truly the US national bird for at least one day a year—Thanksgiving Day. We take the opportunity to pass on some information about turkeys, both historical and nutritional, and tell you about our (rather complicated) way of ensuring that you don't hear anyone say at your Thanksgiving feast: "The turkey is good, but it's a bit dry."

The turkey, our national bird?

Ben Franklin proposed that the wild turkey become our national bird, but the bald eagle (the only eagle native to North America) was chosen instead. People of European descent, as well as Native Americans, were used to considering eagles symbols of bravery—the wild turkey was ungainly and far too secretive. In fact, the wild turkey is a very clever bird, with extraordinary eyesight and the ability to run very fast for short spurts, and to take off into flight in an almost vertical rise—an amazing sight! That's why Native Americans considered he turkey one of the hardest game to catch.

But catch turkeys we did in North America, to the extent that the population dwindled from 10 million when Europeans first arrived on these shores, to 30,000 at the dawn of the 1900's. Hunting bans and efforts at growing and releasing wild turkeys have yielded one of the few bird conservation success stories—along with the success story of the official bird, the bald eagle!

To learn more about wild turkeys, the page on wild turkeys in Matt Miller's blog on nature (written for the Nature Conservancy) called Cool Green Science will give you amazing information.

And to learn more about the wildlife conservation measures to rescue the turkey, visit http://www.nwtf.org/conservation — the National Wild Turkey Conservation Federation site.

By the way, take a look at the face of a wild turkey: its neck and head are red, white, and blue, the colors of the American flag—perhaps Ben Franklin was right!

Turkey portrait. Photo by Peter Lloyd on Unsplash

Where does our domestic turkey come from?

Surprisingly, North American domestic turkeys are not descendants of the wild turkeys that once wandered the plains and wood edges in such vast numbers...and are doing so again. Instead they are descendants of the domestic turkeys of the Aztecs in Mexico.

These domesticated turkeys were brought to Europe in the 16th Century, well before the Pilgrims came to North America in 1620. The turkeys made their way from Spain to France and then to England, where they were gained the name "turkey" for reasons that are not clear. Some say the name came from the "tuke-tuke" sounds that the turkey can make. Others claim that it was the bird's exotic look, coupled with the fact that it was newly arrived from far away—Turkey was thought to be the source of all things rich and strange, and especially anything extravagant in appearance. The French, who passed the bird on to the English, called the bird "dinde" or "dindon" which means "from the Indies"—where people thought Columbus had gone.

The first domestic turkeys were brought to North America in 1607 by the English colonists in Jamestown. I was not able to determine whether the Pilgrims brought turkeys with them from England—if any of you knows the answer, please let us know!).

Domestic turkeys have been subject to extensive breeding and inbreeding, so they have lost the wiliness that enables their wild cousins avoid capture—the idea that a turkey is dim-witted comes from observations of the domestic version; as you can imagine, dim-witted turkeys are much easier to raise...they don't cause any fuss.

Does turkey meat have nutritional value?

Like all meat, turkey meat has the appropriate complement of amino acids to maintain you in good amino acid balance (a topic we discussed yesterday in connection with succotash).

Turkey has less fat than chicken, and less cholesterol, but also less vitamin A. Dark meat turkey has double the amount of iron of dark meat chicken -- which is why dark turkey meat is much darker than dark chicken meat. Light meat turkey, by contrast, has less iron than light meat chicken.*

All in all turkey is a good substitute for chicken, and is a particularly good meat to eat when you want to keep your fat and cholesterol intakes down. You may have noticed that many of the low-fat varieties of sausages and luncheon meats are made with turkey instead of pork or beef. It's not just a question of price.

Are there other important properties of turkey?

Do you fall into a pleasant stupor after Thanksgiving dinner? There is reason to believe that this stupor may be due to the tryptophan content of the turkey, coupled with the high carbohydrate content of the rest of the meal.

In the brain, tryptophan is converted to an important chemical, serotonin, which together with other chemicals is responsible for mellow feelings and sleepiness. But to get into your brain from your food, tryptophan has to cross the blood-brain barrier, which limits the transfer for nutrients from the bloodstream to the brain. There are only a limited number of channels through which tryptophan can be transported across this barrier. Other amino acids compete for passage through these channels, so if other amino acids are present in large quantity in the blood, not as much tryptophan will get into the brain.

If you eat carbohydrates and protein, however, you may get more tryptophan across. The carbohydrates and proteins cause you to secrete insulin into your blood stream. Insulin moves both sugar (glucose) and most amino acids into the body's cells, leaving tryptophan behind. So after Thanksgiving dinner, the levels of tryptophan in your blood are high relative to the levels of the other amino acids, and tryptophan moves more readily into the brain. Thanks to the tryptophan, and most likely to other chemicals and hormones that make their way to the brain as well, we feel full, content and sleepy...and we don't want to eat any more!

This effect is probably not unique to turkey -- chicken has as much tryptophan as turkey, and so do beef and pork, but vegetables or fruits do not have nearly as much tryptophan. So these feelings are probably an effect of meat in general, coupled with a large carbohydrate-containing meal.

So turkey is good for me -- now how do I cook the turkey?

There are as many recipes for turkey and ways of cooking turkey as there are cooks on Thanksgiving! There are dozens and dozens of websites with recipes for turkey, which you can find using your favorite search engine.

If you roast a turkey this Thanksgiving, we would like to remind you of a few food safety precautions, and then tell you how we roast our bird. First the safety precautions:

  • Turkey, and all poultry and eggs, are potentially contaminated with Salmonella and Campylobacter, bacteria that can give you severe gastrointestinal problems with nausea, vomiting, diarrhea, and fever. For the very young, the old, and people with weakened immune systems, these bacteria can be deadly. So please:
  • Handle raw poultry with care, and make sure that it only touches surfaces which you can clean easily, for example cutting boards which you can clean with salt and bleach or in the dish washer.
  • Make sure that you do not use utensils that have touched poultry for any other purpose until you have thoroughly washed them.
  • If you touch poultry with your bare hands, do not touch anything else (not even the faucet) before you have thoroughly washed your hands; if necessary, have someone else turn on the water for you.
  • Be sure to clean all your work surfaces thoroughly after preparing poultry,
  • ...and last but not least, make sure that the turkey or other poultry is thoroughly cooked before eating it.
  • Stuffing, if warmed but not thoroughly cooked, can also be a health hazard due to overgrowth of bacteria in the warm moist environment, so please cook the stuffing outside the turkey. Your turkey will be better cooked as well. Instead, place herbs such as rosemary and sage, as well as a boiling onion or two, in the turkey cavity. 

And now for our roasting method, which we think results in a much juicier breast than traditional methods:

  • First, with a baster, squirt a mixture of olive oil, salt and pepper (and if you like, crushed garlic and juniper berries) under the breast skin of the turkey, followed by a couple of sprigs of rosemary. Rub the surface of the turkey with the same mixture. Then place the turkey breast-up in a roasting pan and cook it in a pre-heated hot (425º F) oven for about 20 minutes. This heat starts to cross link the skin proteins and to form delicious Maillard browning products, made by the joining of sugars and proteins in the skin. Turn the heat down to 325ºF, and take the turkey (which should be starting to become a golden brown) out of the oven, and turn it so that it is breast-down. 
  • Note: if you have some string netting or a turkey rack under the turkey, it will make turning the turkey easier—I use both. Also, always take the turkey out of the oven to turn it and be VERY careful!—this decreases your chances of burning yourself. The fact that the cavity is empty also helps because I can stick a large item such as a barbecue fork inside to help steady the turkey. I usually enlist a helper to hold down the pan and one to help turn the turkey—a process accompanied by much laughter as it isn't easy with a large turkey!
  • Also a non-stick pot or rack will make life a lot easier; if you don't have one of these, be sure that the pot or rack has been treated with fat spray or olive oil (our preference for health reasons), or is spread with a thin layer of butter. But even if the skin sticks, the turkey may not be so beautiful but it will still taste superb!  
  • Put oil or butter in the pan and place the turkey back in the oven and cook until very nearly done. If I am using a rack (recommended), I also add some broth to the pan. Because the breast is down, the juices will run into the breast, so the breast will taste very moist. Be sure to baste the turkey regularly—at the risk of prolonging the cooking time I baste every 15-20 minutes. If you have omitted stuffing the inside of the turkey, the upside-down position will allow you to baste the body cavity easily as well. 
  • Another thing: about 1.5 hours before the end of cooking, I place carrots, halved boiling onions and halved boiling potatoes in the pan around the turkey, and add some more broth, and (I'll admit it here) some butter. Not only do the veggies taste great on their own, but they also add flavor to the basting juices.
  • If you like (and we do) you can put cheesecloth on top of the turkey instead of the tin foil most people recommend. We dribble a generous amount of olive oil on top, but you can use pats of butter which will melt—just make sure the cheesecloth is soaked with oil/butter and turkey juice and baste this too. That way the cheesecloth also helps keep the bird moist.
  • When it looks like the turkey is almost done, take it out of the oven, remove the cheesecloth, and very carefully place the turkey back in the standard breast-up position—again, helpers usually needed.
  • Cook the turkey in this position until it is throughly done, basting regularly, and most of all...

...Enjoy!

And before we leave the topic of turkeys, you might want to learn how the turkey may (or may not) have saved the tambalacoque tree.

More tomorrow!

Please note: the information contained in this blog is for interest only, and does not constitute recommendations for health or any other purpose.

* For those of you curious as to why this might be the case, the reason lies in what the turkey and the chicken do in a day. The darkness and redness of any meat comes from the presence of myoglobin, a protein that contains iron. Myoglobin catches oxygen from the blood stream, and releases it to the muscle as needed for use by its contractile machinery.

Muscles that are used for posture, for example for standing and walking around for long periods of time, need to contract constantly and therefore need a large and steady supply of oxygen. Turkeys are much heavier than chickens and they stand and walk around most of their waking hours, so their leg muscles are well endowed with myoglobin. By contrast our commercial chickens don't stand and  don't walk around, so their muscles don't need much myoglobin.

Our domestic turkeys may stand and strut, but they don't fly around, so they don't need much myoglobin in their breast muscles. In fact they have been bred to have large breasts with very low myoglobin content, because people expect turkey breasts to be white, not pink. Furthermore, the older the bird, the darker the breast meat, so turkeys are bred and fed to grow quickly, before their muscles can accumulate much myoglobin.









Monday, November 20, 2017

Thanksgiving Part 2 — Succotash

A while back, before I retired from the Division of Nutritional Sciences at Cornell University, I helped write answer for a nutrition Q&A website that we called Nutriquest. Was looking over my files and found a four-part series I wrote for Thanksgiving. Here is the second part, lightly edited.  The next parts will be posted over the coming days.

In the US, the fourth Thursday of November is devoted to a very special holiday, Thanksgiving. The day is notable in that it is our national occasion to give thanks for the food that we have—and to help those who do not have enough food, here in the US and throughout the world.

Because food is such a central part of Thanksgiving, and because the Thanksgiving foods have such an interesting history, weaving together nutrition, agriculture and culture, we thought that we would take the opportunity this week to provide you with a series about the Thanksgiving foods, with a couple of recipes and cooking hints thrown in.

Succotash, a combination of corn and beans, is an extraordinarily nutritious dish that the Native Americans presented to the Pilgrims on that first feast of Thanksgiving.

What is succotash?

Succotash is the name given to a number of different dishes combining beans and corn (also known as maize in other English speaking countries). Present day recipes for succotash—and the frozen version I remember from my childhood—combine corn with lima beans. However, the dish the Native Americans introduced to the Pilgrims was certainly not prepared with lima beans—these beans were not available in the Northeast at that time—but was originally prepared with other large beans. You can find recipes on the web featuring black-eyed peas or black beans instead of lima beans—in fact from a nutritional point of view (as we will discuss below) most any fleshy bean will do.
Succotash made with red kidney beans. Image from Wikipedia.

Where does succotash come from?

The name for this mixture of corn and beans comes from the Wampanoag word msíckquatash meaning a boiled stew with corn. The Wampanoags are the Native American people the pilgrims encountered on Cape Cod.

The Native American versions of succotash were made with meat or fish in addition to the beans and corn. However, many of the important nutritional properties of succotash, discussed below, remain if you cook the dish without meat.

The beans that I grew up thinking of as part of succotash—lima beans—were certainly not the original beans used by the Native Americans in the Northeast. Lima beans are a more tropical bean, from Mexico (the small limas) and South America (the larger limas). They do not grow in the climate of New England. They need warm weather, a good amount of warm moisture (no cold water welling up from the ground), and a fairly long growing season—in other words, not the growing conditions prevalent in New England during the Little Ice Age when the pilgrims arrived in America.

We should note that the Native Americans of the Southwest developed strains of lima bean that were drought resistant to suit their climate. One of these is known as Hopi Orange, and is cultivated by the Hopis in the Southwest—see: https://coloradoplateauhorticulture.wordpress.com/2014/02/12/phaseolus-lunatus-how-the-hopi-brought-us-the-ancient-mesoamerican-lima-bean/

Why combine beans and corn in a meal?

Beans and corn in a meal together can give you better quality protein than can either of these foods alone.

What do you mean by better quality?

The proteins we eat are broken down into amino acids, which the body then uses to build its own protein. Our bodies are not able to manufacture most amino acids from scratch—as a result we must eat them pre-formed.

In order for our bodies to build new protein we need to eat the amino acids in the right proportion for making new proteins—as it turns out, this is the proportion found in foods of animal origin, such as meat or eggs, but not the proportion found in individual plant foods.

Then how do you get better quality proteins from plant foods?

By combining certain types of plant foods—and in particular, a grain and a legume, in other words, the corn and beans in succotash.

Grains and legumes are both fairly good sources of protein, because the part we eat is the part that is going to become the new plant. The new plant needs to rely on stores of protein in the seed until it has grown roots and can obtain its own nitrogen for creating amino acids.

Different plant foods have different proportions of amino acids—corn, rice and wheat lack the amino acid lysine, and may have low amounts of two other amino acids, threonine and tryptophan, but they have abundant quantities of methionine. Beans and peanuts have good amounts of lysine, threonine and tryptophan, but are short on methionine. By eating corn and beans together (or rice and beans, or tofu and rice...or a peanut butter sandwich!), you can have each plant food provide what the other is lacking. As a result, with these combinations you can obtain the proper proportion of amino acids, even if you don't eat much if any animal proteins. The process of combining two or more foods in order to get the right proportions of amino acids is called complementation.

Are there other important properties of succotash?

Corn and beans contain some important nutrients in addition to amino acids. These include generous amounts of folate and beta-carotenes. They also contain iron. But remember, the minerals in plant food are less well absorbed than the minerals in animal food, and decrease absorption of iron from animal foods, so don't count on the iron in corn and beans to help you get enough.

As you probably know, carbohydrates (and beans have plenty of them) cause blood sugar levels to go up after a meal. This is a normal process, but diabetics may have high blood sugar levels even before they eat anything, and may not be able to manage rises in blood sugar effectively after they eat. Beans are special in this respect: ounce for ounce of carbohydrate, beans do not raise blood sugar levels as much as other carbohydrate containing foods do. Further, it seems that if you eat beans with other carbohydrate-containing foods (for example corn), you won't get the rise in blood sugar levels you would see with the other foods alone. So beans may play a role in controlling blood sugar, and are an excellent food choice for diabetics. A note of caution, though, for our readers with diabetes—don't let eating beans take the place of monitoring your blood sugar levels, and don't count on beans alone to do what a well regulated well-balanced diet will do for your overall diabetic control.

So succotash is good for me—now how do I make succotash?

There are dozens of websites with recipes for succotash, which you can find using your favorite search engine. Ones we particularly enjoyed reading about are:

  • Plimouth succotash from the Plimoth Plantation, a living museum of 17th century Plymouth, Massachusetts—the recipe feeds 150 people!
  • and the succotash recipes provided by NativeTech.org—Native American Technology and Art—a treasure trove of recipes handed down by Native Americans.

As I peruse all these recipes, certain common features stand out:

  • The proportions of corn to beans are equal—for example, two cups of corn to two cups of beans. This proportion is important for maintaining both flavor balance, and for the complementation of amino acids to work correctly.
  • Many of the recipes call for (skim) milk ; in some recipes milk is added to the extent that the succotash may be transformed into a chowder—also a good choice.
  • Virtually all the recipes have either leek or onion in them—the addition of one or the other will add exciting flavor to the dish, courtesy of activating TRPA1.
  • A number of recipes include diced red peppers—as you can imagine this adds a note of color which looks very festive next to the brown and yellow of the beans and corn.
  • We were interested to note that some recipes included walnuts, chestnuts, or another nut (a tasty choice would be hazelnuts)—if you like nuts, they will add to the healthfulness of the dish.
  • Many recipes go heavy on the salt—remember that you can always add lemon juice to the dish instead of salt; in fact this particular dish is really "picked up" by the judicious addition of lemon juice; we suggest that each person should be allowed to put in the amount of lemon they wish because people differ tremendously in how much lemon flavor is "just right" for them.
  • And a basic note—as we mentioned above, succotash is really a Summer dish, rather than a Fall dish, because in much of the country the fresh sweet corn season and the fresh lima bean season have passed by now. However, to enjoy the best taste possible, see if you can at least find fresh corn, and use dried beans rather than frozen ones. But even if you are stuck to using frozen vegetables, remember that you can add other fresh flavorful ingredients to your heart's content—and most of all,

Enjoy!

...More tomorrow!

Sunday, November 19, 2017

Thanksgiving Part 1 — Cranberries


A while back, before I retired from the Division of Nutritional Sciences at Cornell University, I helped write answer for a nutrition Q&A website that we called Nutriquest. Was looking over my files and found a four-part series I wrote for Thanksgiving. Here is the first part, lightly edited.  The next parts will be posted over the coming days.

In the US, the fourth Thursday of November is devoted to a very special holiday, Thanksgiving. The day is notable in that it is our national occasion to give thanks for the food that we have—and to help those who do not have enough food, here in the US and throughout the world.

Because food is such a central part of Thanksgiving, and because the Thanksgiving foods have such an interesting history, weaving together nutrition, agriculture and culture, we thought that we would take the opportunity this week to provide you with a series about the Thanksgiving foods, with a couple of recipes and cooking hints thrown in.


A NUTRIQUEST THANKSGIVING - PART 1



A cartful of Thanksgiving foods—turkey, cranberries, sweet potatoes, yams, corn and lima beans for succotash, apples and pumpkin for pie, as well as lettuce for salad, and carrots and potatoes and onions to put around the turkey—no wonder these boys are rushing home!
We will start our series with cranberries, and present to you a couple of recipes for cranberry sauce— a link to Mama Stamberg's at National Public Radio, and one of our own, for people who prefer their sauce to be low-fat and a deeper red...

Where do cranberries come from?

Cranberries are native to the New England coast, and are one of three berries that are native to North America (the other two are blueberries and Concord grapes). Cranberries grow on vines that, if well cared for, live indefinitely.

Cranberry vines are very particular about their growing conditions, so the areas in North America where they are grown are limited to New England, New Jersey, the Northwest (Oregon, Washington State, British Columbia), Wisconsin and Quebec. The Northeast, Northwest, Wisconsin and Quebec all share the characteristic that the land was covered in glaciers in the last Ice Age, about 10,000 years ago. The retreat of the glaciers provided the ideal land for the formation of cranberry bogs -- layers of gravel, sand and clay, with abundant peat. The gravel, sand and clay provide just the right amount of drainage for these plants that prefer abundant fresh water, and the peat provides the acidic soil that keeps them healthy.

Here's a map of part of Plymouth County Massachusetts that I gleaned from the USDA Natural Resources Conservation Service. Cranberry bogs are indicated by the red outlines. As you can see the areas are near gravel pits and swamps.




What are cranberries good for?

Vitamin C

Long before vitamin C was discovered, and long before the English Pilgrims came to America, Native Americans knew that cranberries could prevent scurvy. In addition to eating cranberries fresh, they combined crushed cranberries, meat and fat into strips which they dried to form pemmican. Pemmican served as a food for winters and for long voyages, when fruits were unavailable.

Scurvy—the disease caused by vitamin C deficiency—was potentially a serious problem through the long cold winters in the Northeast. These winters were particularly long and cold during the "Little Ice Age" that lasted from the 13th to the early 19th centuries. Cold weather and large amounts of snow meant that fresh fruits, the primary source of vitamin C, were not available. Native Americans developed a number of different remedies for preventing scurvy, including the use of tree material, such as sassafras and American spruce, as well as cranberries. [Side note: spruce tip jelly is particularly delicious! and see footnote below about the native American use of spruce*]

Descriptions of scurvy by English and French voyagers, coupled with the descriptions of the native American remedies, led James Lind (1716-1794) to develop the experiments that showed that scurvy was not due to an infection, as had been thought in Europe, but due to a dietary deficiency. only aft er after Lind's death did the British Navy finally followed Lind's recommendation to add lemon juice to the sailors' rations.**

While scurvy may not be common in the US today, thanks to the year-round availability of fresh fruit, cranberries are a particularly good source of vitamin C.


Cranberry juice and urinary tract infections

Daily consumption of cranberry juice appears to be effective in diminishing the chances of developing, or suffering a recurrence of, urinary tract infections. It has long been thought that cranberry juice prevents urinary tract infection by acidifying the urine.

In fact, cranberry juice does not acidify urine in a consistent way—vitamin C by itself is better at that. Rather, cranberry juice works through another mechanism. The first step in the development of an infection requires that that bacteria stick to each other and to tissue surfaces, so that they don't get flushed out with the urine. Cranberry juice prevents this sticking, and thereby prevents the bacteria from getting a foothold in the urinary tract --and thus prevents urinary tract infections


Cranberry juice and cancer

There is intensive research underway to determine whether cranberry juice plays a role in preventing and treating cancer. There are theoretical reasons why it should do so, and some animal data that support this possibility.***


Cranberry juice, vitamin B12, proton pump inhibitors, and older people

Vitamin B12 requires an acid environment to be released from food. People who are using a proton pump inhibitor (two commercial names: Prilosec and Nexium) for heartburn or an acid stomach, or for stomach ulcers, or who are elderly, have very little acid in their stomachs and not enough to enable vitamin B12 to be released. Cranberry juice, because of its acid content, can take the place of stomach acid, and improve vitamin B12 release and absorption. So if you are over 65 or are on omeprazole, it might be a good idea to drink a glass of cranberry juice every day, along with your animal protein or yeast, the source of vitamin B12 in the diet.


So cranberry juice and cranberries are good for me—now how do I make cranberry sauce?

First, my recipe, developed for people who like their cranberry sauce sweet and spicy:

  • Wash and then plunge about four cups of cranberries into clear boiling water, just long enough so that they burst, and the skins will come off easily;
  • Strain the berries through a strainer (preferably stainless steel so the flavor of the metal doesn't leach into the sauce), and capture the thickened juice;
  • Meanwhile, take a medium red onion (or half a large one) and cook it in vegetable oil until the onion is translucent (you can omit this cooking step if you like your onions to taste strong—cooking breaks down allicin, the pungent compound that activates TRPA1, the cold receptor—red onions are sweeter and milder than others, and I happen to like the flavor without the pungency);
  • Put the berry puree and drained onions in a food processor, and add the following:
  1. a heaping tablespoon or two (or three) of dark brown sugar (how much depends on how sweeeeeet you want your sauce to be);
  2. a pinch of fresh ground pepper;
  3. a 1/4 teaspoon of cinnamon powder, to taste;
  4. a pinch of clove powder;
  5. you may also also want to add a peeled segmented orange, but remember to remove all the white strings, which are bitter;
  6. and then the secret ingredients—a teaspoon of powdered dark chocolate or chocolate liqueur, and a tablespoon of coffee liqueur or cream sherry, or preferably both to total of about one tablespoon (for those of you who don't drink alcohol, you can substitute two teaspoons of very strong coffee); and a teaspoon of dark balsamic vinegar.
  7. At this point I run the food processor to be sure all the ingredients are mixed.
  • Finally, the juice of half or so of a lemon—this takes the place of salt.

I should confess here that I don't really measure when I cook—so when I put together this cranberry sauce I taste it after I add each of the spices and the secret ingredients to see if I have the balance right, and I usually end up adding a little more of one or the other. I add the lemon at the end little by little because it brightens the flavors (it activates TRPA1, the cold receptor)—with tastes in between to be sure not to overdo it. If I overshoot, I just add back one of the ingredients that activates the warm/hot receptors, such as brown sugar or a pinch of cinnamon.

  • Run the food processor again until the ingredients are thoroughly mixed, then put in a glass bowl, and chill immediately. May be kept for one to three days in the refrigerator.
  • Enjoy!
And here's Susan Stamberg's Mama's version of Craig Claiborne's cranberry relish from National Public Radio.

*Note that Jacques Cartier and his companions, in their first winter in what is now Canada (1536), suffered from scurvy, and survived thanks to the remedy prepared for them by local first American women from a tree that was probably a spruce. Samuel de Champlain's men were not so lucky: see Thomas A.Crist, Marcella H.Sorg. Adult scurvy in New France: Samuel de Champlain's “Mal de la terre” at Saint Croix Island, 1604–1605. International Journal of Paleopathology. Volume 5, June 2014, Pages 95-105.
** Peter M. Dunn. James Lind (1716-94) of Edinburgh and the treatment of scurvy.  Archives of Disease in Childhood - Fetal and Neonatal Edition. 1997;76:F64-F65. http://fn.bmj.com/content/76/1/F64
*** Jennifer Clarke, and Laura A. Kresty. Cranberries and Cancer: An Update of Preclinical Studies Evaluating the Cancer Inhibitory Potential of Cranberry and Cranberry Derived Constituents. Antioxidants 2016, 5(3), 27; doi:10.3390/antiox5030027.










Friday, November 17, 2017

Why does eating something sweet and then something sour produce an even more sour experience?

One of the most interesting phenomena you may have observed when eating a sweet dessert then taking a sip of wine, especially a dry wine with a high alcohol content, is that the wine tastes even drier and more sour and tannic than when sipped by itself. Why is this the case?

To understand what is happening we need to go back to a variant of the diagram in my book, "Three Basic Teas & How to Enjoy Them," and add an interesting property of "sweet" that you may have experienced with coffee and some teas.

First the diagram, of the taste cells in a taste bud:

As you can see, there are five different cells in this diagram. The first one, one the left is a Type I cell, and is sensitive to salt, especially to salt at low concentrations. The next three cells are Type II cells. Each Type II cell is sensitive to one taste modality, so in this diagram we have one cell each for bitter, sweet, and umami. Finally, on the right you find a Type III cell, which, as shown here, is sensitive to sour.

In addition to being sensitive to sour, Type III cells are also sensitive to heat, salt, and the burn of alcohol, because they have TRPV1 receptors on their surface.

With respect to salt and bitter (I haven't included an arrow for this interaction, for simplicity's sake): while we do not know exactly how Type I cells communicate their messages, their activation  turns off the Type II cells responsible for bitter sensations. That's why a tiny bit of salt will make tea, wine, and tequila less bitter.

Next to the connections shown in the diagram:

As indicated by the lines, Type II cells can communicate directly to the nervous system and brain. However the primary route of communication is through activation of Type III cells. Bitter, sweet, and umami messages can go through to the brain by either route so long as Type III cells are not activated by something sour or by something that activates TRPV1, such as high salt or alcohol.

However, if you eat something sour or something that activates TRPV1, Type III cells will inhibit messages coming through from the Type II cells, so perception of bitter, sweet, and umami is diminished.

Now to the interesting properties of "sweet:"

You may have had the experience of swallowing a mouthful of tea with lemon and then getting a lingering sweet aftertaste. When a sour compound is washed out and Type III cells are no longer inhibiting the Type II sweet cells, the brain interprets this condition as "sweet." The same thing can happen with coffee and artichokes: they contain compounds that inhibit Type II sweet cells, so that when washed out, you get a sweet aftertaste.

The opposite appears to happen when you wash a sweet compound away with something sour. When sweet goes away, something that is sour will seem more sour because nowType III cells are inhibiting Type II cells. Any sweet message is diminished and the brain interprets this condition as "very sour." This effect can be amplified by alcohol, especially by wine with its low pH and high titratable acid, because TRPV1 on Type III cells will be activated as well. 

In other words, sweet and sour exist in a balance, where the more sour something is the less sweet it will seem, and vice versa.

As a side note, I happen to be homozygous for a mutation in TRPV1 that increases this receptor's activation potential.* As a result, for me any wine with an alcohol by volume (ABV) greater than about 12% burns like crazy. Yet I can tolerate Harvey's Bristol Cream Sherry at 17.6% ABV. Why? Because that sherry is very sweet. The sweetness message is so great that the burn message can't get through. 

Apparently I am not the only person who has this experience: Tim Hanni MW and I have data that shows that people who avoid "big reds," dry wines with a high alcohol content such as California Cabernet Sauvignons, are happy with sweet cocktails that often have an even higher alcohol content than Harvey's Bristol Cream.**

Tim summarizes this pairing experience in the following diagram:


You can find this diagram and a whole lot more in his book "Why You Like the Wines You Like: Changing the Way the World Thinks about Wine." Go to http://www.timhanni.com/publications/.

Oh, and about teas for dessert: if you eat a sweet dessert, black teas will seem more astringent, because highly complexed polyphenols and a host of other compounds in the tea also activate TRPV1—activation of TRPV1 is required for astringency.***

Here's a very good summary reference for the way taste bud cells work: 
Bernd Nilius and Giovanni Appendino. Spices: The Savory and Beneficial Science of Pungency. Rev Physiol Biochem Pharmacol, doi: 10.1007/112_2013_11, Springer International Publishing, Switzerland, 2013. If you can't get the full reference on line, you can get relevant parts of it through googlebooks.

* Alissa L. Allen, John E. McGeary, and John E. Hayes. Polymorphisms in TRPV1 and TAS2Rs associate with sensations from sampled ethanol. Alcohol Clin Exp Res. 2014 October ; 38(10): 2550–2560. doi:10.1111/acer.12527.

** Tim and I have a summary of our report on the topic that you can find at https://www.jancisrobinson.com/files/pdfs/HanniUtermohlenSweetTolerant3.pdf. Thanks Jancis!

*** Nicole Schöbel et al. Astringency Is a Trigeminal Sensation That Involves the Activation of G Protein–Coupled Signaling by Phenolic Compounds. Chem. Senses 39: 471–487, 2014 doi:10.1093/chemse/bju014.
 
 
 

Monday, November 6, 2017

Sara, Georgia, and Jee present green teas and mochi cakes

Another adventure in tea pairing by our intrepid trio, Sara, Georgia, and Jee!

These three tea bloggers have been enjoying tea-food pairings in exquisite venues all around New York City. Here are the links to the tea pairing I'll discuss this time, with its focus on pairing green teas with mochi cakes:

Georgia: http://www.notesontea.com/2017/08/tea-pairing-101-green-tea.html
Sara: http://www.tea-happiness.com/2017/08/tea-pairing-101-green-tea-and-mochi.html
Jee: https://www.ohhowcivilized.com/tea-pairing-101-green-tea/

The green teas were a Japanese Sencha, a Chinese Long Jing, and a Korean Woojeon. 


Left to right, Sencha, Long Jing, and Woojeon. Note the colors from pale green to green-brown with increasing roast.
Image from Jee's blog.
 

The kill-green process (that is, the process for denaturing the oxidase enzymes with heat and thus stopping oxidation) for sencha is steaming. The resulting tea has almost exclusively "green" compounds, and a strong vegetal flavor that Georgia and Sara said tasted like asparagus, while Jee said it was like spinach. As a result the chemicals in sencha activate the cool/cold receptors almost exclusively.

By contrast, the Long Jing is quickly pan-fired and the Woojeon is pan-fired for a slightly longer time. The result is the development of compounds that we taste as roasty and nutty, all against a background of green vegetal-ness. Compounds in these teas activate the cool/cold receptors as well, but also activate the "hot" receptor TRPV1, which is why we get a roasty/nutty quality from them. Depending on the balance of these chemicals in the cup and mouth and on the pairings, one or the other flavor type will dominate.


The mochi cakes. Image from Georgia's blog.
The mochi cake selection included a strawberry with rose that had a fresh strawberry in its center. This cake may have been delicious on its own but was no good with any of the teas. This result is not surprising: the main flavor compound in strawberries, 2,5-dimethyl-4-hydroxy-3(2H)-furanone (Furaneol®), activates the warm receptor TRPV3. Activation of this receptor clashes with activation of the cool/cold receptors, so they cancel each other out and the result is, as Sara put it, "intense sweetness" that overwhelmed any other flavor.

The next mochi cake selection was "Black warabi (bracken) mochi: adzuki bean paste / black warabi (bracken) skin / cinnamon kinako (roasted soybean powder)." It was a runner-up with the Woojeon, according to Jee. The results of this pairing, too, makes sense. The bracken has a somewhat vegetal taste, and cinnamon has compounds that activate both the cold (TRPA1) and the hot (TRPV1) receptors, so it should go well with a tea that has these qualities.

The third mochi cake selection was the winner with all the teas, fresh fig and pistachio mochi: fresh fig / pistachio paste / mochi skin [infused] with black mission fig balsamico. 

Judging from the purple skin color in the photo, as well as the description, the fig chosen for this mochi cake was a Mission fig, considered the most flavorful of the California fig varieties. While the chemical composition of fig fruits has not been exhaustively studied, there are certain compounds that appear to be common to all fig fruits. Among these are (E)-2-hexenal, the compound that grass makes and releases when it is cut. Tea leaves make this compound when they are plucked—it's one of the compounds that give green tea its "green-ness." 

Two other compounds that jumped to my attention in reading the list of fig volatiles were menthol and limonene, which as you can guess from their names are in mint and lemon. They are sensed as cool and refreshing because they activate the cool (TRPM8) and cold (TRPA1) receptors. 

And then the fig was described as "sweet." Well, figs and tea both have methyl salicylate. This is the compound that gives wintergreen its odor, and tastes very sweet. While there is more of this compound in black tea (it is produced during oxidation of the leaves) there is a little in green tea, especially in the more oxidized pan-fired ones. 

One curiosity: I have been fascinated by the characterization of some green teas, including the sencha here, as tasting like asparagus. As I noted in my book "Three Basic Teas & How to Enjoy Them," I have yet to have a green tea that reminds me of asparagus, but clearly I may be alone (or in small company). That said, there is one compound in fig fruit that is common with asparagus, namely (E)-2-nonen-1-ol. It's in cucumber and melons, too, and has a "green" waxy odor. However, figs appear not to have any of the sulfur compounds found in asparagus and in green tea. Yet I can imagine that the asparagus-ness of the figs might complement the asparagus-ness of the sencha.

Pistachios have a number of compounds that activate the cool/cold receptors, at least one of which of which is shared with figs, namely limonene. However pistachios share a different set of compounds with green tea, in particular phenyl acetaldehyde.**

This fascinating chemical combines its "green" aroma with a chocolate/cocoa earthy one. It's a product of a Maillard reaction that occurs with mild heat, so would be more abundant the more roasted the tea (and the roasted pistachio, too). As Sara noted about the Woojeon tea: 
"When I sniffed the dry leaves my nose was instantly met with fresh meadow grass and something a bit surprising-chocolate!"
That would be the phenyl acetaldehyde! Interestingly the flavor of this tea veered away from the usual green grassy quality of the sencha towards the more roasty side. Activation of TRPV1 by the roast products dampens perception of the flavor of grassy chemicals that activate the cool/cold receptors 

What I think the balsamic vinegar in this mochi cake did was to cut the sweetness of the fig and mochi. Acetic acid in balsamico activates the sour responsive cells in our taste buds, which in turn decrease signals from sweet responsive cells and thus our perception of sweetness. 

It was another fascinating excursion into tea and food pairing by our ever-so-observant guides Georgia, Sara, and Jee. And don't forget, as Georgia concludes:
"Experimentation is important in tea and food pairing!" 
All of you out there, keep experimenting and sharing your results, and let's see whether we can figure out why pairings do (or don't!) work.  


Andreia P. Oliveira, Luís R. Silva, Paula Guedes de Pinho, Angel Gil-Izquierdo, Patrícia Valentão, Branca M. Silva, José A. Pereira, Paula B. Andrade, Volatile profiling of Ficus carica varieties by HS-SPME and GC–IT-MS, In Food Chemistry, Volume 123, Issue 2, 2010, Pages 548-557, ISSN 0308-8146, https://doi.org/10.1016/j.foodchem.2010.04.064.
(http://www.sciencedirect.com/science/article/pii/S0308814610005212) 

** Hojjati, M., Calín-Sánchez, Á., Razavi, S. H. and Carbonell-Barrachina, Á. A. (2013), Effect of roasting on colour and volatile composition of pistachios (Pistacia vera L.). Int J Food Sci Technol, 48: 437–443. doi:10.1111/j.1365-2621.2012.03206.x. I should note here that another group appears not to have found phenyl acetaldehyde in pistachios: Ling, B., Yang, X., Li, R. and Wang, S. (2016), Physicochemical properties, volatile compounds, and oxidative stability of cold pressed kernel oils from raw and roasted pistachio (Pistacia vera L. Var Kerman). Eur. J. Lipid Sci. Technol., 118: 1368–1379. doi:10.1002/ejlt.201500336. The differences may be due to both treatment methods and cultivars.

Friday, November 3, 2017

Thoughts about Teforia's demise

As of today, Teforia no longer is in business or selling its products.* Teforia produced the highly celebrated tea making system ("Teforia Selective Infusion Profile System") that took the guesswork out of tea brewing, making it "easy," and produced a "perfect" cup of tea every time. According to World Tea News: 

"At World Tea Expo, Teforia was awarded 2016 Best Tea Industry Innovation Award and was named the 2017 Best (Electric) Tea Brewing Device. The innovative brewer, initially priced at more than $1,000, adjusted steep time, agitation, and temperature for premeasured [loose] tea in capsules sold online as Sips. These premium teas, from established growers such as Yamamotoyama in Japan, were delivered by subscription as fully recyclable and 90 percent compostable. The classic brewer could be programmed by smartphone to brew any tea."**
The Teforia Selective Infusion Profile System. Image from teforia.com  

The article in World Tea News cited four lessons to consider from this failure:

  • Raising large VC rounds is no guarantee of future business success.
  • Good product design is always a big driver for consumer adoption, but the underlying business fundamentals need to be sound for the venture to succeed.
  • High-priced hardware appeals to early adopters and is critical in recouping development costs, but the number of early adopters, while influential, is always small. Pricing devices that people can afford, while balancing margins on the business side is essential to achieve scale.
  • A closed ecosystem such as Teforia, Keurig and Nespresso can work to generate sustaining cash flow, but that’s assuming the consumables they are offering are unique and right-priced. Investors have pulled back from several similar beverage proposals.

What fascinates me is that they mention that the Teforia system is analogous to the Keurig and the Nespresso systems. Both of these systems make their coffee from premade, predosed containers to give you something simple, quick, with no thinking involved. In other words, coffee-on-the-go for people who don't have the time or perhaps even the desire to savor. There is nothing exquisite about these brews, but they serve their purpose.***

The price tag of Teforia was pretty stiff for the convenience of drinking tea as you might coffee: simple, quick, with no thinking involved—you can do as well with a tea sachet or a bottled tea, if you just want a cup of tea to go. 

The goals of the Teforia system, though, were to automate and make fool-proof the brewing of high-end teas, so the flavor would be perfect every time. Which it was.

Yet those of you who appreciate high-end teas will quickly say that the joys of sipping an exquisite tea lie in looking for and selecting the tea, in the aesthetics of pots, cups, and utensils, and especially in the ritual of the brewing process itself, not to mention in the surprise of tasting the results—no two brews are exactly alike, nor should they be.

So I believe that we should add to the four lessons laid out in World Tea News a fifth lesson, namely that preparing a cup of delicious tea is as much an art as a science, and requires a human hand and mind at every step of the way. Taking the human touch out of the process may yield a great flavor but not a great joy. 

* Here's a video of the Teforia system in action: https://www.youtube.com/watch?v=ixqM77riEOo
** http://worldteanews.com/news/teforia-closes-down
*** I'm working on a coffee book to go with my "Three Basic Teas & How to Enjoy Them," so have been diving deep into understanding coffee. By virtue of coffee's chemistry, the Keurig and Nespresso systems simply cannot give you a delicious coffee that you could savor the way you would savor tea.