Category Archives: Fruit

Pirates of the Carob Bean

Maybe the name takes you back to gentler days of Moosewood Cookbook and the dusty spicy local co-op. Or maybe you were a kid back then and fell for a chocolate bait-and-switch. Whether you are sweetly nostalgic or wary and resentful, it’s worth giving carob another chance. Katherine argues that it’s time to pull this earthy crunchy 70’s food into the superfood age. She offers foraging tips and recipes to help you get to know carob on its own terms.

From November through January, the carob trees in my neighborhood dangle hard, lumpy, dark brown fruits resembling lacquered cat turds. They are delicious and nutritious and of course I collect them. I am, without apology, a pod plundering, legume looting, pirate of the carob bean. If you seek adventure and happen to live in California, Arizona, or on the Mediterranean coast, you can probably pilfer some carob fruits yourself and play with them in your kitchen. If you lack local trees or the pirate spirit, you can order carob powder and even whole carob beans with one simple click.

Although plundering season begins just as the year is ending, I always wait until January to gather carob fruits for two reasons. First, carob functions mainly as a healthful chocolate substitute, and during the holiday season, fake chocolate just seems sad. In January, however, eating locally foraged carob feels virtuous and resourceful. Second, November and December are when my local carobs make the flowers that will produce the next year’s crop, and those flowers smell like a pirate’s nether parts after a shore leave. Or so I imagine, and not without precedent. A man who should have been inured to such salty smells, Pliny the Elder, natural historian and commander in the Roman Imperial Navy, described the flowers as having “a very powerful odor.” It’s not clear why these flowers have a sort of seaman scent, since the main volatiles wafting from the flowers – linalools and farnesene – smell like lilies and gardenias (Custódio et al., 2006). In any case, I keep my distance until the flowers have finished mating season.

Carob trees

Despite their stinky flowers, carobs make great street trees and produce a valuable crop in many Mediterranean-type climates. They are beautiful, tolerant of dry and poor soils, pest resistant, and tidy. Carobs are legumes – like familiar peas and beans – but they belong to a different branch of the legume family (Caesalpinioideae), one that contains mostly trees and woody shrubs with tough inedible fruit (Legume Phylogeny Working Group, 2017). Carob pods look about as edible as Jack Sparrow’s boots, and the species’ scientific name, Ceratonia siliqua, means “horny long pod,” which well captures the intimidating nature of their leathery fruit. But as you will see below, the fruits are easy to harvest and process, and their sweet pulp is worth seeking out.

Whole carob pod (left) and immature pod opened to show pulp and seeds. The pulp hardens and turns pale brown at maturity. Click to enlarge.

Evidence suggests that people have indeed been seeking out carobs for a long time. Although carob’s origin is uncertain, the species seems to have evolved in the eastern Mediterranean and wild plants would have been available to foragers well before agriculture arose in the region. The plant geneticist Daniel Zohary believed that carob was domesticated late, perhaps only in Roman times, but that it spread quickly throughout the Mediterranean region once people learned how to propagate the trees. Remains of horny pods were found in the 1st century ruins of Pompeii (Zohary, 2002), where carob trees perished alongside our noble friend Pliny the Elder. The University of Cyprus has recently embarked on a project called “Black Gold” to reinvigorate the island’s ancient tradition of carob cultivation and develop new food products from it. Right now, countries around the Mediterranean produce tens of metric tons of carob annually, and one Australian company has jumped into the market with an Aussie Sharkbar.

HistoireDesMétéores - p419

Is there a carob tree here? Mort de Pline (Death of Pliny). Jean-Édouard Dargent [Public domain], via Wikimedia Commons

Carob powder is derived from the fruit wall, and this is what we will process for the recipes below. A less visible but incredibly common carob product appears on ingredient lists as “locust bean gum,” which comes from the gelatinous endosperm of the seeds. It is used to thicken cosmetics and almond milk and to keep crystals from forming in ice cream.

“Locust” is a common name for several of carob’s close relatives, hence the confusion, but I’m still puzzled by the marketing choice of “locust” over “carob” for a list of ingredients you might eat or rub into your face. Squeamishness over true six-legged locusts may underlie another common name for carob, “St. John’s bread.” His “meat was locusts and honey,” but surely John the Baptist subsisted on sweet tree pods and not icky arthropods.

In ancient Greece and Rome, dry carob seeds provided a standardized weight for jewelry, which we now call the carat. So if your own pirate’s code precludes stealing actual gold and gemstones, you can still fill your bandana with carats of a sort.

24 carat magic!

Becoming a carob pirate

First, I must state clearly that we Botanists in the Kitchen are committed to sustainable use of wild foods and do not endorse actual pirate behavior, including stealing carob beans from private property or taking anything from parks or forests where collecting is prohibited. The interests of others and the conservation status and abundance of any plant must always be considered.

Fortunately, taking a few handfuls of carob fruits before they hit the ground does not damage the trees or deprive anyone but slugs of a snack. Carobs are not native outside of the Mediterranean and anyhow they do not reproduce readily by seed, so you are unlikely to affect their propagation. And honestly, as much as I love them, publicly available carob pods are not in high demand. In fact, you may be doing your community a service by keeping them off the sidewalk. After all, the trees are planted for their foliage, not their fruits.

To collect carobs, you must first find them. The Friends of Urban Forests have collected a useful series of tree maps for many cities, including several where carobs grow. City streets, public parks, and college campuses are good places to look as well. Even without a map, if you have local carobs, you should have little trouble because carobs are among the easiest to spot once you have a search image. They brandish bold compound evergreen leaves with elliptical thick green to blue-green leaflets, about 1.5 inches (4 cm) across, arrayed in pairs along a red-tinged rachis.

A single large carob leaf, with four pairs of leaflets. At dusk, leaflets fold up towards each other, like pairs of hands, thanks to the thick pulvinus at the base of each leaflet. Click to enlarge.

Their trunks become rakishly knobby and gnarled with thick ribs running along their length. They often have low branches, making harvesting easy, and in mid-winter the black pods dangle in conspicuous clusters. Of course, during early winter flowering season you can always find them with your nose.

But there is a twist in the story. Not all carob trees make pods. Ceratonia siliqua is dioecious, with some individuals bearing only pistillate (“female”) flowers and others bearing only staminate (“male”) ones. And yes, female flowers smell just as bad as male flowers do. My favorite local tree, however, is one of the occasional hermaphrodites, whose flowers bear both pistils and stamens. It is plausible that humans selected for hermaphroditic individuals during domestication (Zohary, 2002), and that my local genotype reflects that history.

Inflorescence with hermaphroditic flowers. Flowers have both pistils (stigma, short style, ovary) and stamens (anthers on filaments). They lack petals, and their sepals are very short, obscured by the green nectary. Click to enlarge.

Each flower in a cluster is tiny and completely lacks petals. A set of short sepals is almost entirely hidden by a fat green gland that secretes odoriferous nectar to attract and reward insects. That offensive scented nectar seems gratuitous, however, because the flowers have several hallmarks of wind-pollination: highly reduced perianth (sepals and petals), well exposed anthers, and dioecy (separate male and female flowers). On the other hand, they lack other wind-pollination traits, most obviously a long and feathery stigma to capture wind-borne grains and numerous anthers tossing out buckets and buckets of pollen.

Only a few ovaries per inflorescence survive to become a carob pod. This one is happy to see you. Click to enlarge.

Attracting insects thus appears to be important, and one study reports that the flowers don’t make any fruit without wasps and flies to pollinate them (Arista et al., 1999). Unfortunately, it looks like we have to tolerate the raunchy smell to get to the treasure. Nobody ever said a pirate’s life was a bed of roses.

 

Recipes

Although carob is often used as a chocolate substitute, and it does taste similar to cocoa, carob has a unique flavor profile that deserves to be taken on its own terms. The flavor can be enhanced by roasting the pods gently for about 10 or 15 minutes. Roasting also turns residual moisture in the fruits into steam, which swells the cavity inside so that the seeds come out more easily.

It’s more fun to make your own, but you can find commercial carob powder in many stores, and both powder and syrup can be found online.

Carob “mocha”

Use about 5 pods per cup.

Roast pods in a toaster oven at a low temperature (about 250ºF or 120ºC) for 10-15 min until they swell up and blister slightly. Their high sugar content makes pods burn easily and deeply, so keep a watch on them and remove them quickly if they start to char.

Crack open the pods and remove all the seeds.

Grind the pods in a coffee or spice grinder to the consistency of ground coffee.

Carob mocha brewing in a French press

For rich flavor, I like to use about half a cup of ground carob in a 4-cup French press to yield two hefty mugs. Brew for about 15 mins.

Add heated or steamed milk to taste.

Carob syrup

Use to sweeten tea or coffee or to make carob-peanut balls.

You will need about 8 pods and two cups of water for every tablespoon of syrup desired. Pods do not need to be roasted, but allowing them to dry out for a week reduces the tannins and yields a smoother flavor.

Rinse any dust from the pods. Remove “stems” (pedicels). Hand break the pods into 1-inch lengths or roll over them with a marble rolling pin or a thick-walled wine bottle to crack and crush them. Pirates can use a bottle of rum.

In a sauce pan, bring to a boil one cup of water for every 4 pods. Remove from heat, add the broken pods, cover and allow to steep for several hours, until the water is the color of iced tea.

Reheat the water and simmer the pods for another 30 mins, or until the liquid looks like breakfast tea or very weak coffee.

Remove the pods and continue to simmer the liquid extract until the depth of the water is about half an inch.

At this point, right before it is thick enough, the syrup can burn very easily. For the final reduction, either strain it into a small sauce pan and heat gently under constant vigilance, or strain it into a glass measuring cup and microwave it a few minutes at a time.

You will know it is ready when it has been reduced in volume to half a tablespoon per cup of starting liquid. It will thicken a bit when it cools, but will always be more like maple syrup than molasses. Refrigerate for storage.

Carob peanut balls

Peanuts and chocolate are a classic combination, but peanuts and carob really belong together, as they are in the same family. If you can’t make or find carob syrup, you can use clover honey instead and sort-of add a third member of the fabulous Fabaceae.

Roast and grind 2 or 3 carob pods, as described in the mocha recipe above, but continue to grind to make a very fine powder. Put the powder through the finest sieve you have to remove grainy bits. A gold filter for coffee or a very fine tea strainer works well. The leftover grainy bits can be steeped for tea.

Mix a tablespoon of powder with about a teaspoon of carob syrup (or a bit less honey).

In a coffee grinder or mini food processor, grind a half a cup of whole peanuts into smooth peanut butter.   Add salt to taste. Add the powder and syrup mixture and blend to combine.

Allow the mixture to sit for an hour as the powder binds with the peanut butter.

Roll mixture into about a dozen small balls. Roll the balls in carob powder to coat them. You may need a second coat if they become sticky.

Carob peanut balls (right) and carob powder (left). This batch was rolled in sugar for some sparkle. Sugar is not necessary for taste because carob is naturally sweet.

References

Arista, M., Ortiz, P. L., & Talavera, S. (1999). Apical pattern of fruit production in the racemes of Ceratonia siliqua (Leguminosae: Caesalpinioideae): role of pollinators. American journal of botany, 86(12), 1708-1716.

Custódio, L., Serra, H., Nogueira, J. M. F., Gonçalves, S., & Romano, A. (2006). Analysis of the volatiles emitted by whole flowers and isolated flower organs of the carob tree using HS-SPME-GC/MS. Journal of chemical ecology, 32(5), 929-942.

Legume Phylogeny Working Group (LPWG) (2017). A new subfamily classification of the Leguminosae based on a taxonomically comprehensive phylogeny The Legume Phylogeny Working Group (LPWG). Taxon, 66(1), 44-77.

Pliny the elder. The Natural History of Pliny, vol. 3, Chapter 16 (8), translated by John Bostock and Henry Thomas Riley, 1855

Zohary, D. (2002). Domestication of the carob (Ceratonia siliqua L.). Israel journal of plant sciences, 50(sup1), 141-145.

A holiday pineapple for the table

This deep dive into pineapple anatomy is our contribution this year to the very fun Advent Botany essay collection, a celebration of plants that are at least somewhat tangentially connected to the winter holidays. In previous years we’ve contributed essays on figs, peppermint, and sugar.

December is the time to bring out the fancy Christmas china, polish the silver pitchers, and . . . bedeck your best bromeliads. In 2017, as in 1700, no proper hostess can be without a pineapple for her centerpiece. Here we unpack the botany of pineapple, which is as complicated and fabulous as its cultural history. A proper hostess, after all, should also be able to dazzle her guests with tales of tropical fruit morphology. Continue reading

Botany Lab of the Month: Jack-O-Lantern

Happy National Pumpkin Day! Turn carving your Halloween Jack-O-Lantern into a plant dissection exercise.

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The first Jack-O-Lanterns were carved out of turnips in 17th-century Ireland. While the large, starchy hypocotyls (fused stem and taproot) of cruciferous vegetables are anatomically fascinating, this post will be about the stuff you are more likely cutting through to make a modern Jack-O-Lantern out of squash. Continue reading

Preserving diversity with some peach-mint jam

We are knee deep in peach season, and now is the time to gather the most diverse array of peaches you can find and unite them in jam. Katherine reports on some new discoveries about the genetics behind peach diversity and argues for minting up your peach jam.

Jam inspiration

Fresh peaches at their peak are fuzzy little miracles, glorious just as they are. But peaches cooked into jam and spread across rough toast lose their buttery mouthfeel and dripping juice. To compensate for textural changes, processed peaches need a bit more adornment to heighten their flavor, even if it’s only a sprinkling of sugar. Normally I am not tempted to meddle with perfection by adding ginger or lavender or other flavors to peach jam. This year, however, as I plotted my jam strategy, the unusual juxtaposition of peach and mint found its way into my imagination over and over again, like the insistent echo of radio news playing in the background. Peach and mint, peach and mint, peach and mint – almost becoming a single word. To quiet the voice in my head I had to make some peach-mint jam. The odd combination turned out to be wonderful, and I’m now ready to submit the recipe to a candid world. As we will see below, it’s not without precedent. Mmmmmmpeachmint jam. Continue reading

Buddha’s hand citrons and a wish for peace on earth in 2017

Winter is the season for citrus fruit, and January is the month for breaking out of old routines, so stop staring at your navel and learn about one of the weirder citrus varieties.

I’ll never forget the day one of my general botany students brought to class a Buddha’s hand citron, pulled from a tree right outside our classroom. I had only recently moved to northern California from Indiana, and I’d never seen anything like it: it was a monstrous mass of a dozen pointed twisted fingers splayed irregularly from a stout base. It had the firm heft and girth of a grapefruit and the unmistakable pebbled skin of a citrus fruit, so I wondered whether my student had found a grossly deformed grapefruit; but the oil in the peel smelled heavenly and not at all like a grapefruit. In class we cut through a big finger and found no juicy segments, just white citrus pith all the way through.

Immature Buddha's hand on the tree

Immature Buddha’s hand on the tree

We eventually discovered that this fascinating fruit was a Buddha’s hand citron, Citrus medica variety sarcodactylis, meaning fleshy (sarco-) fingered (-dactyl) citron. Since that day many years ago I’ve become an unapologetic (if surreptitious) collector of the fruits from that same campus tree. The citrons do not drop from the tree on their own, yet I often find one or two lying nearby, probably torn off by a curious tourist or student and then abandoned. Obviously these fruits need a good home, and where better than the window sill in my office?

The first time I left one closed up in my office over a weekend, I opened the door on Monday morning to a waft of fruity floral aroma. It turns out that many people in China and India use the fruit to scent the air, although in west Asia and Europe the fleshy fingers are more often candied or used to flavor alcohol. I do both: the fruits make my office smell nice until they are fully yellow, and then I cook them.

It can be difficult or expensive to get your own hands on a fingered citron, but it’s easy to find a navel orange almost any time of the year. Fortunately, the patterns underlying the morphology of the fingered fruit can also be seen in an everyday navel orange. Between our photos of Buddha’s hands and your own navel orange, you should be able to follow along at home. Continue reading

How giant pumpkins got so big: A Q&A with Jessica Savage

Biologist Jessica Savage answers a few of our questions about her research on the physiology behind giant pumpkin size.

In October 2014, a giant pumpkin grown by Beni Meier of Switzerland tipped the scales at 1056 kilograms (2323 pounds) and set a new world record for the heaviest pumpkin ever weighed. Modern competitive pumpkin growers have been imposing very strong selection on pumpkin size for decades. Pumpkin fruit size keeps climbing, and old records are broken every year or two (Savage et al. 2015).

Beni Meier with his 2014 record-winning 2323-pound pumpkin, presumably a specimen of the Atlantic Giant variety of Cucurbita maxima. Photo from here.

Continue reading

Triple threat watermelon

Will seedless watermelons make us superhuman or turn our children into giants?  Hardly, but they do give home cooks the power to count chromosomes without a microscope.   Just a knife or a hard thunk on the sidewalk are enough to get a watermelon to spill its genetic guts.

If you were reading a Hearst Corporation newspaper in late 1937, you might have thought humanity would eventually be swallowed up by giant carnivorous plants, unwittingly unleashed by uncontrolled biotechnology.  The San Francisco Examiner reported on November 21st of that year that the discovery of an “elixir of growth,” meant that “…science may at last have a grip on the steering wheel of evolution, and be able to produce at will almost any kind of species…”  including “…a plague of man-eating ones.”  In 1937 Americans had much more important things to worry about, just as we do now.  Still, that discovery may in fact have threatened one cherished aspect of the American way of life by triggering the slow demise of late summer state fair watermelon seed spitting contests.  It doubtlessly paved the way for seedless watermelons, and in 2014 the total harvest of seedless watermelons on American farms – nearly 700 thousand tons – outweighed the seeded watermelon harvest more than 13 to 1 (USDA National Watermelon Report). A similar pattern is emerging this year.  Is there no stopping the attack of the seedless watermelons?

Image from microfilm of an actual page in the San Francisco Examiner, published Sunday November 21, 1937. Found in the Media and Microtext Center of Stanford University Libraries.

CLICK to read. Image from microfilm of an actual page in the San Francisco Examiner, published Sunday November 21, 1937. Found in the Media and Microtext Center of Stanford University Libraries.

And more important, how is it even possible to get seedless fruit from an annual plant?  From a plant whose only mode of reproduction is through those very seeds?  From a plant that cannot make suckers as bananas do and cannot be perpetuated endlessly through grafts like fruit trees and vines?   Such is the challenge posed every single year by watermelons, but thanks to the “elixir of growth” discovered by Albert Blakeslee and subsequent work by Hitoshi Kihara, one of the most prominent agricultural geneticists of the 20th century, the world has an elegant solution. Breeders continually improve the varieties available, and consumer demand keeps growing, yet seedless watermelon production methods have remained essentially unchanged for three quarters of a century. Continue reading

The new apples: an explosion of crisp pink honey sweet snow white candy crunch

What’s in a name?  An apple with an old fashioned name could taste as sweet, but it might not sell.  The most sought after branded varieties reveal what people look for in an apple: sweet and crunchy and bright white inside.  Do the fruits live up to their names?  Are Honeycrisp apples crunchier than others?  Do Arctics actually stay white?  We zoom in on the cells to find out.

Some of you will remember the era when the Superbowl halftime show repeatedly featured Up With People.  That was around the time when Granny Smiths arrived in our supermarkets and finally gave Americans a third apple, a tart and crunchy alternative to red and golden delicious.  Those were simple days.  Continue reading

Apples: the ultimate everyday accessory

Infinity scarves? No. They won’t keep doctors away. Apples are the ultimate everyday accessory (fruit). Katherine explains where the star in the apple comes from. Could it be due to a random doubling of chromosomes? We also give readers the chance to test their apple knowledge with a video quiz.

Although apples are not particularly American – nor is apple pie – they color our landscape from New York City to Washington State, all thanks to Johnny Appleseed. Or so goes the legend. Everyone already knows a lot about apples, and for those wanting more, there are many engaging and beautifully written stories of their cultural history, diversity, and uses. See the reference list below for some good ones. There is no way I could cover the same ground, so instead I’ll keep this post short and sweet (or crisp and tart) by focusing on apple fruit structure and some interesting new studies that shed light on it.
Of course if you do want to learn more about apple history but have only 5 minutes, or if you want to test your current knowledge, take our video quiz! It’s at the bottom of this page. Continue reading

Walnut nostalgia

Walnuts may not seem like summer fruits, but they are – as long as you have the right recipe.  Katherine takes you to the heart of French walnut country for green walnut season.

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Public domain, via wikimedia commons

English walnuts do not come from England. The English walnut came to American shores from England, but the English got them from the French. The (now) French adopted walnut cultivation from the Romans two millennia ago, back when they were still citizens of Gallia Aquitania. Some people call this common walnut species “Persian walnut,” a slightly better name, as it does seem to have evolved originally somewhere east of the Mediterranean. But the most accurate name for the common walnut is Juglans regia, which means something like “Jove’s kingly nuts.” I think of them as queenly nuts, in honor of Eleanor of Aquitaine, because if any queen had nuts, she certainly did. During her lifetime the Aquitaine region of France became a major exporter of walnuts and walnut oil to northern Europe, and it remains so more than 800 years later. Continue reading