Posts

Cranberry

Cranberries are harvested in late autumn, just in time to celebrate the holidays. Whether you prefer to enjoy cranberries in a jam, as a sauce from the can, juiced, dried, or fresh, there’s no denying that cranberries are festive. They’re tart, dark red, and pair really well with a turkey dinner (according to science). Read more

Garlic

Image Credit: Robert Benner (mullica/Flickr)

Image Credit: Robert Benner (mullica/Flickr)

If you’ve ever made the mistake of devouring three bowls of James Beard’s Garlic Soup a few hours before The Job Interview Of Your Life (I’m not speaking from experience here), you will recognize the frantic moment in which you pray that 1) the handful of mints burning in your mouth have superpower strength, or 2) your interviewers cannot smell, or 3) whoever you’re meeting had four bowls of garlic soup. Ahhh, the allure and woe of garlic. Why do you hate me if I love you so much?

Known for its distinct aroma and taste, Allium sativum – or garlic, as most of us know it – makes dishes sweet and pungent while it turns breaths foul and fetid. But what exactly causes garlic breath? More importantly, how do you get rid of it?

Image Credit: (fiverlocker/Flickr)

“Dear god, what did this guy have for lunch?”  —  Image Credit: (fiverlocker/Flickr)


The Breakdown of Garlic Breath

Garlic contains many sulfur compounds, but the ones most responsible for garlic breath are: diallyl disulfide, allyl methyl disulfide, allyl mercaptan, methyl mercaptan, and allyl methyl sulfide (AMS). The gases released by all of these compounds, except forAMS, originate in the oral cavity when we mechanically crush garlic in our mouths, so brushing your teeth and tongue will reduce the presence of the mouth-originated odors. However, good dental hygiene doesn’t usually entirely get rid of the smell because AMS is what causes unwelcome garlic breath, and this can linger for several hours or even days.

Background Credit: Crispin Semmens (conskeptical/Flickr)

Allyl Methyl Sulfide (AMS), the unwanted pungent houseguest that overstays its welcome. — Background Credit: Crispin Semmens (conskeptical/Flickr)

AMS is a sulfur compound formed inside the body from allyl mercaptan, so instead of originating in the mouth, AMS is produced in the microflora of the gut. The resultant gas quickly evaporates into the bloodstream, which then diffuses to the lungs and infuses each breath of air that leaves our bodies with traces of strong-smelling allyl methyl sulfide. And if that isn’t wonderful enough, the compound is also released through pores of the skin, which is why you may notice a lingering body odor after garlic-heavy meals. Unfortunately, AMS does not get metabolized in your gut and liver like many other molecules that we eat, so it takes much longer for AMS to breakdown – which is why the AMS stays in the body for many hours later. [1]

SOLUTIONS: When brushing your teeth (sadly) isn’t enough

Image Credit: Robert Bertholf (robbertholf/Flickr)

Image Credit: Robert Bertholf (robbertholf/Flickr)

  • EAT THIS: Parsley, Spinach, Mint, Apples, Pears, plus any fruits and veggies that are prone to browning (think avocados, bananas, potatoes, etc.)

    WHY: These foods contain an enzyme called polyphenol oxidase. (The same enzyme is what makes your fruit salad look brown!). When this compound is exposed to oxygen, it reacts in a way that reduces both the odors of the volatile compounds and the formation of more AMS. [2]

Image Credit: A Girl With Tea (agirlwithtea/Flickr)

Image Credit: A Girl With Tea (agirlwithtea/Flickr)

  • DRINK THIS: Green Tea, Coffee,  Ku-Ding-Cha (a bitter-tasting Chinese tea),  Prune Juice

    WHY: These drinks contain a polyphenolic compound called chlorogenic acid, which is another chemical that works to deodorize garlic-derived sulfur compounds on human breath. [2]

Image Credit: (Unsplash/pixabay)

Image Credit: (Unsplash/Pixabay)

  • ALSO DRINK THIS: Lemon juice, Soft Drinks, Beer, Hot Cocoa (and other acidic foods/beverages)

    WHY: When garlic cloves are cut or crushed open, they release an enzyme called alliinase that facilitates the reactions which produce compounds responsible for the smell of garlic. Because these drinks have a pH below 3.6, they quickly destroy alliinase and minimize the formation of garlic volatiles. [2]

Image Credit: Mike Mozart (jeepersmedia/flickr)

Image Credit: Mike Mozart (jeepersmedia/flickr)

  • DRINK THIS INSTEAD OF WATER: Milk!

    WHY: While drinking water works extremely well for reducing garlic breath, milk works even better because of its extra fat, protein, and sugar. Specifically, whole milk is effective in the reduction of the hydrophobic compounds diallyl disulfide and allyl methyl disulfide because of its high fat content. Note that drinking milk during a garlic-heavy meal does a better job of killing garlic breath than drinking milk afterwards, because the milk is able to directly react with the volatile compounds when it is mixed with garlic. [3]

Makes me think garlic ice cream might actually be a genius all-in-one odor-neutralizing dessert!

References Cited:

  1. Suarez, F., Springfield, J., Furne, J., Levitt. M. Differentiation of mouth versus gut as site of origin of odoriferous breath gases after garlic ingestion. Am J Physiol. 1999; 276(2):425–30.[http://ajpgi.physiology.org/content/276/2/G425]

  2. Munch, R., Barringer, S.A. Deodorization of Garlic Breath Volatiles by Food and Food Components. Journal of Food Science. March 2014; 79(4): C536-533.

  1. Hansanugrum, A. Barringer, S.A. Effect of Milk on the Deodorization of Malodorous Breath after Garlic Ingestion. Journal of Food Science. August 2010; 75(6): C549-558.


Eunice LiuAbout the author: Eunice Liu is studying Neuroscience and Linguistics at UCLA. She attributes her love of food science to an obsession with watching bread rise in the oven.

Read more by Eunice Liu


Food, Wine, and Biochemistry

Photo Credit: Kirti Poddar (22598380@N07/Flickr)

Photo Credit: Kirti Poddar (22598380@N07/Flickr)

Wine and food pairing may seem like a refined art form, cultivated through trial and error to best suit the individual, but what if we told you there was also a science to it?

When it comes to wines, the word “tannin” is thrown around a lot. In broad terms, tannins are a type of flavonoid molecule, which reside in the bark, leaves, and unripe fruits of a wide variety of plants. The three major classes of tannins are hydrolyzable, condensed, and phlorotannins. Where wine is concerned, phlorotannins are nonexistent (only found in brown algae); hydrolyzable tannins leach from the oak barrel that wines have fermented and aged in; and condensed tannins come from the grapes [1]. While hydrolyzable tannins may be present in all wines, since winemaking traditions necessitate oak barrels, these offer little towards wine taste, mouthfeel, and color. Viniculture favors condensed tannins. Originating from the grape skins, seeds, and stems that go into winemaking, condensed tannins play a key role in wine-tasting.

Red wines are made using the entire wine grape, obtaining their color from anthocyanin, another type of flavonoid molecule found alongside tannins in grape skins. By contrast, white wines are produced from just the grape pulp. Since the tannin-containing parts of the grape do not go into white wine production, white wines are often lower in tannin levels and generally lack condensed tannins.

So how is all this discussion about tannins relevant in choosing which wine to serve alongside a steak dinner?

Tannins contribute to two wine-tasting characteristics: bitterness and astringency [1,3]. Anyone who has ever eaten an under-ripe grape has experienced an exaggerated sensation of astringency, as under-ripe grape skins contain high tannin concentrations. However, astringency should not be confused with bitterness or sourness; these tastes are perceived on the tongue through bitter and sour taste receptors. Conversely, astringency is a physical sensation, frequently described as a dryness or roughness on the tongue.

A sip of wine is just the beginning of the biochemical process behind astringency. Our saliva contains proteins that are able to organize water molecules about themselves, which increases saliva viscosity to above water viscosity, giving rise to “mouth lubrication” [2]. Tannins in wine readily bind to saliva proteins. This causes a snowball effect: tannin-bound proteins end up clumping together with other tannin-bound proteins, creating an aggregate [3]. This aggregate inevitably precipitates out of our saliva. With fewer free, unbound saliva proteins, there is a decrease in saliva viscosity, subsequently leading to a decrease in mouth lubrication [3]. In short, tannins physically dry out the tongue.

In this respect, high-tannic red wines pair well with high-protein foods. With more tannins binding to food proteins, saliva proteins are spared and the wine doesn’t feel as astringent in the mouth. Tried-and-true pairings include Cabernet Sauvignon with a rack of lamb, Pinot Noir with pork roast, and Chianti with grilled salmon.

Besides the protein interactions, tannins have also been shown to favorably bind to fats [4]. Fats are polar molecules by nature (they don’t like to interact with water). On the other hand, saliva is mostly water. By attaching to tannins, fats hinder tannins from mixing with saliva and binding to proteins. Essentially, fats wash the tannins away. For this reason, wine paired with cheese is a great treat, as is a gourmet burger with a glass of Zinfandel.

Armed with this knowledge, why not begin your own wine and food adventure? May we suggest a Cabernet with mac and cheese with spam?

Photo Credit: Jose Tagarao (lidocaineus/Flickr)

References cited

  1. Goode, Jamie. “Tannins in Wine.”Wine Anorak.
  2. Hatton M, et al. Lubrication and viscosity features of human saliva and commercially available saliva substitutes. Journal of Oral and Maxillofacial Surgery. June 1987;45(6):96-99.
  3. Cala O, et al. NMR and molecular modeling of wine tannins binding to saliva proteins: revisiting astringency from molecular and colloidal prospects. The FASEB Journal. November 2010;24(11):81-90.
  4. Furlan, A, et al. Red wine tannins fluidify and precipitate lipid liposomes and bicelles. A role for lipids in wine tasting? Langmuir. May 2014;30(19):18-26.

Alice PhungAbout the author: Alice Phung once had her sights set on an English degree, but eventually switched over to chemistry and hasn’t looked back since.

Read more by Alice Phung