Difference Between Bitter and Sour

Scores and notes are to music as flavors and aromatic molecules are to gastronomy. There is no such shared reality with flavors, yet the perception of them varies wildly from person to person. There are delicate sensibilities and strong ones. Such differences of perception depend on one’s taste buds which are found on our tongue, which in turn allows us to experience all kinds of tastes. Taste is the main sensory modality by which we assess whether a potential food is safe to eat or dangerous. Taste is probably the only external sensory element required for life. That being said, there are four primary qualities of taste that are perceptible to our tongue – sweet, salty, bitter and sour. Recently, a fifth sense, umami (or savory), has been added to the four classic taste modalities. As humans, we develop certain taste preferences over time, which make us crave some foods while dislike a few. We take a look at two qualities of taste to see how they compare – bitter and sour.

What is Bitter?

The bitter taste, or bitterness, is one of the most sensitive among the four classic taste modalities and probably the least understood. It was originally associated with a poisonous plant source, so it considerably produces aversive reactions. As the technology advanced, so did our understanding of the bitter taste. People have started to realize that not all bitter compounds are poisonous. Bitterness is produced by several different types of chemical substances such as sulphate, quinine, morphine, caffeine, nicotine, magnesium sulphate, and so on. Bitter compounds are not only numerous but also structurally diverse.

Often perceived unpleasant by many, bitterness is commonly found in strong, earthly flavored foods such as green leafy veggies (cabbage, spinach, zucchini, bitter gourd, etc.), and spices like turmeric. A wide variety of beverages also contain bitter components that make them so unique – beverages like tea, coffee, beer, ginger ale, and some non-alcoholic beverages like soda. However, bitter tasting foods can have a positive effect on our body such as prompting basic metabolic responses in the stomach to aid in weight reduction and detoxification of the body.

What is Sour?

Sour is one of the four classic taste sensations, along with the recently determined umami (savory) and is often associated with acidity. Often found unpleasant, sourness is the result of high quantity of acids in foods such as citrus, which includes limes or lemons. Acids such as lemon juice, vinegar, and many organic acids present in fruits contribute mainly to the sour taste. Sourness is mainly detected by the taste buds along the side of the tongue, and is presumably important in regulating dietary intake of H+. In fact, the degree of sourness is proportional to the degree of dissociation of H+ from an acid.

The cells responsible for detection of sour taste are taste receptor cells (TRCs) that express the PKD2L1 receptor, which belongs to the family of TRP (transient receptor potential). The mechanism of detection of sourness is yet to be fully studied, and whether the taste hails from the sensation of extracellular or intracellular H+ levels is still unclear. Sour foods that can be healthy additions to our diet include fermented foods, dairy products like yoghurt, fruits like cranberry, tart cherries, processed pickles, salty cheese, lentils, maple syrup, egg whites, dried peas, etc.

Difference between Bitter and Sour

Taste Receptor

 – The taste sensation is attributed to a wide variety of molecules that interact with saliva to facilitate the sense of taste through a set of specialized cells called taste receptor cells. These are basically proteins that help us recognize the different types of taste modalities. The receptors responsible for sensing the bitterness in substances are TAS2R receptors, which are coupled to G proteins and comprised roughly 25 intact receptor genes and several pseudogenes.

The cells responsible for detection of sour taste are taste receptor cells (TRCs) that express the PKD2L1 receptor, which belongs to the family of TRP (transient receptor potential).

Health Benefits 

– The bitter-tasting foods have their own health benefits, which include improved digestion, healthy blood sugar level, protection against heart diseases and diabetes. Bitter foods are rich in fiber and bitter greens like kale, radicchio, endive, etc. help us manage our cholesterol level and detoxify blood. They also aid in weight reduction and detoxifying the body.

Sour-tasting foods are very nutritious and are rich in plant compounds called antioxidants, which provide protection from cell damage. Fermented sour foods like raw, unfiltered apple cider vinegar kill harmful bacteria and helps manage blood sugar levels and diabetes, and acts as a home remedy for many health ailments. Dairy products such as yogurt are a protein rich food which makes up for a healthy accompaniment.

Foods

 – Bitter green leafy vegetables include dandelion, kale, mustard, radicchio, broccoli rabe, cabbage, spinach, arugula, watercress, and so on. Bitter beverages include tea, coffee, beer, red wine, and cocktails. Other bitter things include dark chocolate, bittermelon, saffron, cranberry, cocoa, vinegar, grapefruit, cinnamon, etc.

Sour taste most commonly attributes to citrus fruits, which include lemon, grapefruit, Mandarin oranges, key lime, yuzu, kumquats, etc. Acidic foods include confectioneries and cakes, white vinegar, white rice, alcoholic beverages, and so on. Sour cream, yogurt, and buttermilk are among the most common fermented dairy products that are sour in taste. Other sour foods include cranberry, tart cherries, processed pickles, salty cheese, lentils, maple syrup, egg whites, dried peas, etc.

Bitter vs. Sour: Comparison Chart

Summary

Nature provides us with different taste buds to help us identify the different taste sensations, including sourness and bitterness. Bitter foods have a strong, pungent taste, which often come from green leafy veggies such as spinach, bitter gourd, dandelion, kale, and more. The sour taste is often attributed to the high amounts of acids in foods such as citrus. The bitter taste is due to cations, while the sour taste is due to increase in hydrogen ion concentration (H⁺). Bitterness is probably the most sensitive among the taste sensations whereas sourness is the indicative of acid levels.

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