Truffles mushrooms reside in a Holy Grail land of taste preference. They call to mind ancient French banquet meals and rural truffle hunters and their dogs. Scarce and expensive, the truffle industry satisfies market demand by bottling their musky scent in so-called truffle oils.
The Pacific Northwest is an unsung truffle backwater—when compared to the famous truffle growing regions of Périgord, France and Alba, Italy. Most residents never see, smell nor taste our region's outstanding earthy delicacy, the Oregon black truffle. Lately though, I've binged on them, developing a classic neuropsychological food craving.
Why are truffles such high-end luxury goods and how do they induce food cravings? This post confronts these basic questions. Along the way, it offers some practical advice for home cooks preparing truffles for the first time.
A Truffle Taste Primer
Truffles are a catchall category of mushrooms. Hence, taxonomic definitions become scientifically necessary to tell them apart. The overall grouping refers to the underground fruiting bodies of fungi in the Ascomycota phylum in the kingdom Fungi. They grow in symbiotic relationships with host tree roots. For those unfamiliar with truffles:
Truffles have no stalk, no gills and are usually formed underground. They tend to be spherical, although their shape is often molded by stones in the soil in which they are growing. When mature, truffles tend to be firm or even hard to the touch, dense, and almost woody, rather than soft and fragile like many mushrooms.
Unlike other fungi, the truffles do not release their spores at maturity and instead have evolved strong odors to attract consumers. These aromas are made up of complex mixtures of volatile organic compounds, including alkanes, alcohols, esters, aldehydes, ketones, and terpenes of wide ranging polarity and molecular weight. . . . These attract animals, including insects and mammals, which eat the truffles. The spores then pass through the gut before being deposited in a well-fertilized piece of ground perhaps many kilometers from where the truffles were eaten.
Europeans tend to narrowly interpret what constitutes a true truffle, limiting them to fungi in the genus Tuber or the family Tuberaceae. The restricted truffle category preserves prized cultural heritage: black winter truffles from Périgord, France (Tuber melanosporum) and white Alba truffles from Italy (Tuber magnatum). These gourmet truffles grow in the "smallish, sharply defined foothill regions" of these two countries.
Starting in November/December each year, these two truffle species dominate headlines during their harvest seasons. They represent the gold standard of truffle flavor. Although less famous, the Motovun Forest in Croatia's Istrian Peninsula is also home to delicious white truffles—sometimes passed off in the black market as the much more valuable white Italian (or Alba) truffles.
The white Alba truffle stands at the apex of price and flavor. When in season, it is two to five times more expensive than the Périgord black winter truffle.
The excellent pungent but pleasant aroma and peculiar but superb flavor of the Italian white truffle is reminiscent of garlic and cheese but with subtle undertones of methane. Chemically, the aroma is dominated by the principal volatile component bis-methylthiomethane (= 2,4-dithiapentane). Because this and other volatiles are lost with excess heat, the Italian white truffle is either used uncooked or added to dishes after cooking, for example, as a flavouring for pasta or salads.
Although it does not fetch the extremely high prices commanded by the Italian white truffle, the Périgord black truffle (Tuber melanosporum) is recognized by most as being the truffle delicacy. Its aroma and flavor are much more robust than the Italian white truffle, so it can be cooked, albeit at low temperatures, and incorporated into sophisticated recipes rather than just thinly sliced raw over hot food.
Some Chinese truffles (i.e., Tuber indicum and T. formasanum) closely resemble the Périgord black winter truffle. Opportunities to fool even seasoned truffle buyers abound. Common ways to snooker consumers include keeping Asiatic truffles in a closed container to concentrate their aroma, or to intersperse these less precious truffles with Périgord truffles. Asiatic truffles might even be sprayed with volatile chemical components to approximate the odor of Périgord black truffles. Preparing a truffle dish in France with Asiatic truffles and not declaring them can subject a restaurateur to fines, jail time or both.
Oregon White and Black Truffles
While Oregon is known for its white truffles—Tuber oregonense and T. gibbosam—connoisseurs would not confuse their flavor with the white Alba truffle. Oregon white truffles exhibit an "attractive strong garlicky or cheesy aroma, which becomes pungent and metallic with age, but the best Oregon winter white truffles have a sweet, musky, cedarlike aroma with hints of cinnamon, nutmeg, and vanilla." While perhaps biased because he grew up in Oregon, the legendary James Beard compared them favorably with white Italian truffles.
In contrast to the Italian white and Périgord black truffles, the Oregon black truffle belongs to a different taxonomic family (Morchellaceae) and genus and species—Leucangium carthusianum—and therefore some deem it to be a false truffle. Gastronomes, however, consider its flavor to be equal or even superior to Périgord black winter truffles.
A Pacific Northwest mycology scholar describes a typical Oregon black truffle in fine anatomic detail:
It had a dark brown, almost black, and very roughened peridium [outer skin], and in cross section the gleba [an inner solid mass of spores] was beautifully marbled with dark chambers surrounded by pale, whitish veins. It had a pronounced, fragrant smell that was, as I describe it, a very powerful truffloid odor—that is, fragrant, but a bit musty too. Peculiar enough that I couldn't nail down any comparable odor for reference. The odor was so strong that it filled my mycology lab and library and was very noticeable to others entering. My wife Pam thought the odor was disagreeable. I didn't find it objectionable, just really strong.
It appears that this species is associated only with the coastal form of Douglas Fir here on the West Coast and the trees have to be relatively young (10 to 60 years old) . . . .
During this past growing season ending in April, I consumed all sorts of imported truffle varieties until I discovered Oregon black truffles in my own figurative backyard. Johnny on the spot, I developed a sixth sense of when they would be sporadically available from my favorite vegetable/fruit vendor in Seattle (whose identity is my trade secret). I even managed to procure and cook with the largest, grapefruit-sized Oregon black truffle (~ 5 oz.) my produce vendor had seen this year. A truffloid odor filled my kitchen. I would open the kitchen door occasionally to take a "hit" from a Ziploc bag storing my truffles wrapped in paper towels.
Home Cooking Truffle Experiments
Newcomers to truffle consumption may well stumble out of the gate cooking truffles at home, as this description aptly attests:
[Sautéed] a piece of truffle in vegetable oil and fried up an egg. Seemed to be very rich tasting like when I eat too many crabs. Couple hours later developed stomach churning and cramps for about half hour then diarrhea. Feel good now, but don't think I'll try anymore. [Signed "Young Doug"].
Young Doug committed some basic truffle cooking gaffes, causing gastrointestinal distress. He overcooked them for starters in vegetable oil (ugh!); and then paired them with an uncomplementary fried egg preparation (yuck!). Unlike this truffle novice, I experimented with tried-and-true truffle recipes with my bounty. I did not try to learn from scratch. Young Doug's cooking naiveté caused his indigestion and trips to the bathroom—not truffles massacred on a stovetop.
My own favorite truffle preparations became delicate soufflés and complex mushroom/chicken sauces served with fresh pasta or over baked polenta. The keys to successful truffle recipes seemed five-fold:
After luscious truffle soirées, dinner companions began noticing recurring side effects. The post-dinner mood seemed more euphoric and convivial than normal. Was it just the wine? We also all later reported sleeping harder after these truffle-filled meals, often with unusually vivid dreams. What could possibly explain these soporific and psychotropic states?
Odors, Emotions, and Your Brain
Without consciously recognizing it, we inhale and process scents constantly. On average, you breathe 20,000 times a day, and with each breath invite new olfactory stimuli into your mental world. Recent research indicates that your olfactory system can discriminate among and between at least one trillion different smells.
We are probably all acquainted with the "Proustian" effect, i.e., of the floodgate of memories triggered when the novelist Marcel Proust ate a madeleine (a small sponge cake) dunked in tea. For research scientists studying consumer psychology, the ability of a scent to trigger secondary associations is known as a "superadditive" effect. This latter term applies to "scent's ability to enhance the imagery value of a memory trace."
In more plain terms, olfactory cues "are hardwired into the brain's limbic system, the seat of emotions, and stimulate vivid recollections" per Professor Gerald Zaltman, author of How Customers Think (2003). Once a scent is embedded in one's memory, visual cues can cause it to be resurrected and "experienced." These "memory markers" help promote product recall. Hence, watching a person savor the smell of cup of coffee on TV can cause the viewer to experience these same olfactory sensations.
This is not a surprising result given that "olfaction and emotion are deeply connected by neuroevolution." The "emotional and associative learning substrates of the brain grew out of tissue that was first dedicated to processing the sense of smell." As Prof. Rachel Herz, one of the leading scientific experts in olfactory psychology, explains:
[T]he informational significance of emotion and olfaction is functionally the same. The most immediate responses we have to an odor are simple binary opposites: like or dislike, approach or avoid. Emotions convey the same message: approach what is good, joyful, loving; avoid what is bad, fearsome, or liable to cause grief.
Truffle oils represent the epitome of scent marketing. The truffles's relative scarcity and expense as a foodstuff means that many consumers will only experience truffle odor through a chemical concoction in a so-called truffle oil. The chemically derived odor will usually be a synthetically derived form of bis-methylthiomethane. If you read the FDA-required nutrition facts labels, often you will find that that the truffle oil contain no truffles at all. If any actual truffle extracts are incorporated, they are likely present in only minute levels.
How to Form a Neuropsychological Food Craving
Scientific research is only scratching the surface as to why the smell of truffles can lead to cravings for this foodstuff. A food craving is defined as "an intense desire to consume a particular food that is difficult to resist." Neuroimaging studies indicate that "food cravings appear idiosyncratic and distinct from the subjective experience of hunger." "Exposure to visual and/or olfactory cues associated with preferred foods can elicit craving for those foods."
In the parlance of neuropsychologists, evaluative conditioning influences our food choices. Flavor-flavor learning takes place by pairing one flavor we like with another. Flavor-flavor conditioning, for example, can be applied to increase children's consumption of fruits and vegetables. A "biopsychosocial theory of food cravings suggests that food cravings can develop by pairing food intake with other conditions," such as internal emotional states.
My firsthand experience with truffle flavor-flavor conditioning occurred through pairing truffles with already preferred foodstuffs, such as mushroom/chicken cream sauces, fresh pasta and fine wines. Good feelings about the latter foods then transferred onto truffles subliminally. As a burgeoning truffle craver, exposure to truffle odors is likely activating regions of my brain controlling reward, motivation and memory. In contrast, Young Doug’s immediate flavor-flavor experience with truffles induced a food aversion.
My avid consumption of truffles is also a form of neuropsychological sensation seeking. Sensation seekers are attracted to foods that are hot (spicy), highly flavored, or unusually textured.
Unfortunately, extant scientific research appears to tell us nothing substantively about how or why truffle ingestion seems to induce longer periods of deep (or slow wave) sleep or perhaps generates a mild euphoria. Scientists did discover that truffles produce a hormone, androstenol, which is a pheromone—defined as a natural chemical produced by an animal and transferred by air that affects the sexual physiology of another animal—also secreted in low concentrations in humans. This finding lends credence to the long-held belief—never scientifically validated—that truffles are aphrodisiacs.
Given the sheer expense of procuring truffles for scientific research studies, these truffle-influenced states may well remain as neuropsychological mysteries into the foreseeable future.
Don't be a Young Doug and squander your truffles through overcooking or by pairing them with poor flavor/texture combinations. His awful recipe from scratch induced an immediate, perhaps lifelong neuropsychological aversion to truffles. Instead, if you're lucky (or wealthy) enough to obtain some white Alba truffles in late autumn, try shaving them atop a Carnaroli Risotto Biologico with a Castelmagno Mousse, like that served at Thomas Keller's Per Se restaurant in Manhattan. You’ll arrive in taste bud heaven, with vivid dreams to boot.
 See I. Hall, G. Brown and A. Zambonelli, Taming the Truffle: The History, Lore, and Science of the Ultimate Mushroom (2007), p. 56.
 See B. Luther, "The Oregon Black Truffle, Leucangium Carthusianum: A Fascinating and Fragrant Find from a Local Backyard," Spore Prints: Bulletin of the Puget Sound Mycological Society (May 2009), available online, https://www.psms.org/sporeprints/SP452.pdf.
 J. Hansen, “A Fungus in Every Pot," New Scientist (August 26, 1982).
 See J. Sakurai, "Truffles in Paradise. (And It's Not Italy.)," New York Times, available online, https://www.nytimes.com/2016/11/20/travel/croatia-truffles-istria-italy.html. The author of this post went truffle hunting in September 2017 in Croatia's Motovun Forest with the truffle hunter, Nikola Tarandak, featured in this article.
 See n. 1, p. 73.
 Id., pp. 59-60.
 Id., pp. 223-224.
 Id., p. 789
 See n. 2, pp. 1 and 5.
 Id., p. 5
 C. Bushdid, et al., "Humans Can Discriminate More Than 1 Trillion Olfactory Stimuli," Science, Vol. 343, p.1370 (March 21, 2014).
 M. Lwin, et al., "Exploring the superadditive effects of scents and pictures on verbal recall: An extension of dual coding theory," 20 Journal of Consumer Psychology 317, 318 (2010).
 See http://www.neurosciencemarketing.com/blog/articles/does-your-marketing-smell.htm., article entitled "Does Your Marketing Smell?" From Neuromarketing: Where Brain Science and Marketing Meet (July 30, 2007).
 R. Herz, "The Emotional, Cognitive, and Biological Basics of Olfaction," p. 91, Sensory Marketing: Research on the Sensuality of Products (2010), edited by A. Krishna.
 C. Martin, et al., "Food Cravings: A Central Construct in Food Intake Behavior, Weight Loss, and the Neurobiology of Appetitive Behavior," Handbook of Behavior, Food and Nutrition (2011), p. 742.
 R. Havermans and A. Jansen, "Acquired Tastes: Establishing Food (Dis-)Likes by Flavour-Flavour Learning," Handbook of Behavior, Food and Nutrition (2011), p. 79
 See n. 17, p. 751
 T. Alley and K. Potter, "Food Neophobia and Sensation Seeking," Handbook of Behavior, Food and Nutrition (2011), p. 716.
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