Tag Archives: Food

The complexity of taste!

A recent blog on how the loss of sense of smell can intensify taste makes some interesting points. The two that have interested me for a while are the contribution of trigeminal nerve sensations to consumption (for lack of a better word) and the hazy area of taste (if we get into the murkier ion channeling side of things).

mmmm…truffles!

The touch sensations reported at the end of the blog (e.g., creaminess, dryness of tannins) that may be intensified with loss of smell are not actually taste/tastebud related.  There are three nerves sending information to the brain from the tongue that comprise the gustatory system (vagus, glossopharyngeal [innervate TAS1R andTAS2R], and facial nerve [chorda tympani branch innervates the TAS1R and TAS2R taste receptors]. The trigeminal nerve also plays a strong role (falsely reporting the burn in chili or the cool in fats and methols etc). Personally, I am driven by my nose and trigeminal nerve. I love intense experiences like chili peppers, wasabi, and methol but I dislike spongy or slimy experiences like mushrooms or okra (respectively and sometimes both for mushrooms!). Oddly and despite my dislike for other fungi, I do like truffles but have only ever eaten them in France (so infrequently at best!). The olfactory system alone is complicated enough without adding taste to make flavour let alone adding touch to make texture/sensation. But, perhaps we need to think more about this when it comes to food taste and preferences. If someone dislikes eating a food, will that same person report disliking its smell because of the association with an unpleasant trigeminal (touch) experience?

Taste is under-rated and for a reason due to its minimalistic suite of traits. Taste may be more complicated if we push beyond the five basics by first considering detection methods: salty and sour are detected through ion channels while sweet, bitter, and umami detected through G protein-coupled taste receptors (same type of receptor used in olfaction). Salt and sour may eventually be found to have receptors associated with them as well (sour is ahead of salt in evidence right now several possible candidate genes).*

The complex mechanism of sugar detection may also explain why creating an artificial sweetener that tastes natural is so difficult; specifically blame it on one of three receptors involved in sugar detection, TAS1R3. A 2012 study on taste receptor evolution suggests the importance of dietary niche in the structure and function of an animal’s sensory system:

tet cookie

•Repeated and independent loss of function in TAS12R in Carnivores throughout evolution (but why does my blue cat love sweets and my tabby steal cookies!?)•Sweet and umami receptor genes were nonfunctional in two sea mammals (dolphins  also had nonfunctional bitter taste receptor genes) and have a diminished sense of taste; in unrelated studies, olfaction is also odd in sea mammals b/c they lost then regained some Class 1 olfactory genes (those that detect water-borne odors).

Champagne cocktail: note wide mouth flute for smelling the drink while drinking!

Bitter is a good one too. There are multiple TAS2Rs expressed in one taste receptor cell which raises the question: can mammals distinguish between the tastes of different bitter ligands?  There are many more bitter compounds than we have receptors for–combinatorial coding like olfaction? I personally love bitter (but not all types of bitter) and will often take a classic champagne cocktail (but without the sugar lump).

While I will always take smell over taste, I am excited about the future taste research and also more work on the involvement of facial nerves (especially the trigeminal nerve!).

*DOI:10.1038/35098087, DOI:10.1126/stke.3492006tw292, DOI:10.1046/j.0022-7722.2003.00062.x, PNAS 103 (33): 12569-12574

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Is food preference simply repetition?

recent Science New Post (brought to my attention by @elizabethjrowe) presents research trends in food science: the pairing of retronasal olfaction and taste reception in studying flavour and the knowledge pairing of culinary experts and scientists within a relatively new journal FlavourI am glad that food sensation (for lack of a better word to describe the complex process of perception, taste, smell, hedonic value, and preference) is getting increasing amounts of attention! From an anthropological perspective, however, the evolutionary and cultural underpinnings of these studies is still missing from the dialogue–something I hope to rectify in the coming years!

The article leans towards the idea that repetition is the driver of food preference–and it starts in the womb–and could be summed up by a quote from a taste and smell scientist: “What makes lasagna loved is that the odors have been paired to a source of calories.” I don’t buy that argument for many reasons. From personal experience, the food I ate growing up (typical British Isles meat and two boiled veg) is not at all what preferred when I started to taste foods outside the home. When my mother was home in Ireland, my father would make spicy food–chilis and burritos (not something he grew up with either). To this day, I love the heat of chilis and zing of spice–let’s just say I have been tempted to drink Sadistic Mistress PainSlut (if you are a fan of heat, hers are the only sauces I have found that have a variety of flavour and burn)! I’m not the only one–there is some truth to programming; we tend to share our mother’s food preferences but that is why kids are pushed to try new things and adults too–b/c we aren’t programmed that way. From professional and anthropological experience, there is a lot more to our evolutionary genetics when it comes to smell and preference and certainly much of that is driven by cross-cultural variation. Cross-cultural variation depends partly on the varying environmental challenges faced by our ancestors as they adapted to new places and diets.

We have identified only a few ligands that bind to odor receptors and have not yet fully explored the difference between retro- and ortho-nasal smelling let alone the complex neural signalling that communicates that complex bundle of information to the brain along with the basic five (or six) tastes. Thankfully for people like me, there’s so much more to find out and let’s hope inter-disciplinary and inter-sectoral journals like Flavour are just the start of a multi-disciplinary/sector journey into what makes great food!

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Tomatoes

tomatoes1024.jpg Tomatoes are such a perfect food. tomatoe.jpg

Sadly, many people strongly dislike them. I can’t imagine why. They are the perfect evolutionary color–a bright red when ripe to attract vision-oriented primates. They are loaded with nutrients and a vital part of a healthy diet. They are also so versatile–great raw or cooked, on their own or with other foods. Tomatoes are one of the few foods we eat that are great in any stage of readiness. Canned, freezing, stewing–all only serve to enhance their nutrient output. I would go so far as to argue that tomatoes are intentionally begging us to eat them by being so accommodating to all the various methods modern humans have invented to process food for storage. In our modern society where too many people eat overly processed and nutrient poor food, the tomato is a salvation.

Ever since Columbian exports of New World foods, the tomato has infiltrated world culture to the point that many cuisines are incomplete without them. Yet, so many varieties have been lost without lament. Such a perfect food reduced to the plain hothouse variety usually found in stores. Unless you have a store that stocks heirlooms, that is. Heirlooms are plant seeds from old lines.

heirloom.jpg I recently tried a pack of heirloom varieties that included a purple striped Central American species (that incidentally came via Canada). It had such a pungent acidic taste that perfectly complemented the sweet cherry red and yellowy-orange species in the same box.

If I had to survive on a desert island (and I have given this quite a bit of thought), I think I would happily make do with tomatoes, basil, garlic, bananas/plantains, coconut, and dark chocolate (OK, cacao).

more-tomat.jpg basil.jpg banan.jpg plantains.jpg coco.jpg cacao.jpg caco2.jpg

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