Friday, October 12, 2012

The Sweet Taste of Bitterness


Camellia Sinensis is an evergreen plant which is bitter by nature. I am sure no one likes bitterness in the beginning. A child will spit out healthy steamed vegetables due to their bitter flavors. It is just a natural instinct, animals will not eat bitter plants since most of it might be poisonous. It is a way of survival.  So why do the Chinese love tea? I guess it's because of tradition, a culture which runs deep in ancient ethos. The ideology of hardship in the beginning and prosperity at the end that could apply to everything in Chinese Culture. The Sweet Taste of Bitterness.

In our modern world, society has created luxury and abundance. A detachment of nature and a nurturing of personal egos. We have the choice of selecting things that we fancy, meanwhile rejecting the taste that is foreign to us. We hate things that are unknown to us and destroy ideas that we dislike. Most often, I am puzzled by decaffeinated coffee, non-alcoholic beer and smokeless cigars. The only conclusion that I could have is we are spoiled; we can like a certain trait of a thing and reject the rest of it? Same as loving a person for a particular trait but trying to change the rest to meet your expectations? 

I have been consistently defending tea or trying explain to clients that tea is bitter. It's just one part of its complex character. What defines good or lesser tea is if the bitterness changes and how it changes once you drink it. Some tea changes from bitter to honey, to sweet plums, or to mint. Some changes your idea of life... that will be another topic. 
To bore you all, here are some interesting comparison on bitterness from searching the University of the internet:

WINE
Bitterness in wine is elicited primarily by flavonoid phenols, which are bitter and astringent, and by ethanol. Monomeric flavonoid phenols are primarily bitter but as the molecular weight increases upon polymerization, astringency increases more rapidly than bitterness. The chiral difference between the two wine flavan-3-ol monomers produces a significant difference in temporal perception of bitterness: (-)-epicatechin is significantly more bitter and had significantly longer duration of bitterness than (+)-catechin. Ethanol enhances bitterness intensity and duration, whereas varying wine pH has little or no effect on perceived bitterness. Whereas PROP status had no significant effect on temporal perception of bitterness or astringency, subjects with low salivary flow rates took longer to reach maximum bitterness and astringency intensity and reported longer persistence of both attributes than high-flow subjects.

COFFEE
Bitterness is sometimes a negative, but omnipresent, aspect of the beverage.  At low levels, bitterness helps tame coffee acidity and adds another favorable dimension to the brew.  However, at high levels, a bitter coffee compound can overpower the other components present in coffee producing an undesirable effect.  Bitter coffee results from the interaction of certain compounds with the circumvallate papillae on the back of the tongue.  Astringency, on the other hand is caused by compounds that can precipitate salivary proteins on the tongue. Consumers will often mistakenly attribute astringency and any other potent characteristic of the coffee to the bitterness.   Therefore, this article will discuss those compounds that are responsible for contributing to the bitterness of the coffee and those compounds that cause astringency in the coffee.

Why Does Coffee Taste Bitter?
Various coffee scientists have made the following observations concerning bitter coffee, which were presented in a review article by McCamey:

The perceived bitter taste in the mouth from coffee is correlated to the extent of extraction.  The extent of extraction is dependent upon the roast, the mineral content of the water, water temperature, time, grind size, and brewing procedure. 

  • Bitterness is reduced in coffee brewed with either soft or hard water relative to distilled water (Voilley et al., 251).
  • Bitterness is correlated with the total dissolved solids of a coffee.
  • Perceived coffee bitterness is lower when coffee is brewed hot than when cooler water is used. This is hypothesized to be due to the heightened aromatics released in hot coffee, which counteract the bitterness (Voilley et al., Eval., 287).
  • Coffee bitterness is decreased by the addition of sucrose, sodium chloride, or citric acid. Hydrocolloids, in general, were found to decrease the perception of coffee bitterness (Pangborn, 161).
  • Robusta coffee contains higher levels of both caffeine and chlorogenic acids, which are partly responsible for bitterness and astringency in coffee.
  • Several investigators have found that the processing of coffee (wet or dry processing) does not affect the perceived bitterness of coffee even though the overall flavor profile is significantly different (Clarke and Macrae; and Clifford and Wilson).
  • Caffeine has a distinct bitter taste and has a test threshold of only 75-155 mg/L (60-200 mg/L found by Clarke). However, Voilley considers caffeine to only account for around 10% of the perceived bitterness in coffee.
  • Hardwick found that the bitterness of caffeine is weakened when polyphenols are introduced.
  • Maier reported that the sourness of coffee was diminished by increased bitterness.
  • Astringent and metallic tastes in coffee have been attributed to dicaffeoylquinic acids, but not the monocaffeoylquinic acids (Ohiokpehai et al., 177).
  • Trigonelline is perceived as bitter at concentrations of 0.25%, whereas chlorogenic acids necessitate a concentration of 0.4% at pH of 5 to be perceived as bitter (Ordynsky, 206). Trigonelline degradation is proportional to roast degree. Its byproducts include pyridines, which are said to contribute a roasty aroma to the coffee.
  • Quinic acid--a degradation product of chlorogenic acids--is present at twenty times its threshold value and is partly responsible for the perceived bitterness in coffee (McCamey, 176).
  • Furfuryl alcohol is thought to contribute a burnt and bitter taste to coffee (Shibamoto et al., 311).
CIGAR
The bitterness from cigars is not from aging but instead from the fermentation process.  Most tobacco leaves are naturally sour so to soften the bitterness and reduce the tobacco's acidity, Cuban tobacco leaves are cured in two fermentation stages.  After fermentation, the tobacco will contain less tar, nicotine, have a balanced colour and be less sour. However, it's possible that some tobacco leaves require more time than others to properly ferment and may still be bitter when it is selected for cigar production.  Don't worry, even though this bitterness can be a common occurence, long-term aging can reduce it and improve your cigar(s) taste. Cohiba cigars don't have a bitter taste because Cohiba tobacco is put through an extra fermentation process which refines the tobacco even further and makes it truly premium. Also, using a cigar punch can increase the bitter flavour because your saliva can mix with the tobacco and create a strong tobacco residue that builds up in the small punch opening.  This will cause a strong, sharp, bitter taste the more the cigar is smoked.  Fortunately, this can be corrected by not smoking the cigar too quickly.  By slowing down your smoking pace, there will be less tobacco/saliva residue buildup at the head of the cigar.

TEA (Camellia Sinensis)
Tea contains catechins, a type of antioxidant. In a freshly picked tea leaf, catechins can compose up to 30% of the dry weight. Catechins are highest in concentration in white and green teas, while black tea has substantially fewer due to its oxidative preparation. Research by the U.S. Department of Agriculture has suggested the levels of antioxidants in green and black tea do not differ greatly, as green tea has an oxygen radical absorbance capacity (ORAC) of 1253 and black tea an ORAC of 1128 (measured in μmol TE/100 g). Antioxidant content, measured by the lag time for oxidation of cholesterol, is improved by the cold water steeping of varieties of tea.

Tea also contains L-theanine, and its consumption is strongly associated with a calm but alert and focused, relatively productive (alpha wave dominant), mental state in humans. This mental state is also common to meditative practic. L-theanine, and the stimulant caffeine at about 3% of its dry weight, translating to between 30 mg and 90 mg per 8 oz (250 ml) cup depending on type, brand, and brewing method. A small amounts of theobromine and theophylline.  also contains in tea. Due to modern environmental pollution, fluoride and aluminium have also been found to occur in tea, with certain types of brick tea made from old leaves and stems having the highest levels. This occurs due to the tea plant's high sensitivity to and absorption of environmental pollutants. Although tea contains various types of polyphenols and tannin, it does not contain tannic acid. Tannic acid is not an appropriate standard for any type of tannin analysis because of its poorly defined composition.
Catechins have a broad range of physiological functions and act as the main taste ingredient of green tea. Although catechins show a strong bitterness, the bitter taste receptor for catechins has not been fully understood. The objective of this study was to identify the receptor for the major green tea catechins such as (-)-epicatechin (EC), (-)-epicatechin gallate (ECg), (-)-epigallocatechin (EGC), and (-)-epigallocatechin gallate (EGCg). By the cell-based assay using cultured cells expressing human bitter taste receptor, a clear response of hTAS2R39-expressing cells was observed to 300μM of either ECg or EGCg, which elicit a strong bitterness in humans. The response of hTAS2R39-expressing cells to ECg was the strongest among the tested catechins, followed by EGCg. Because the cellular response to EC and EGC is much weaker than those of ECg and EGCg, galloyl groups was strongly supposed to be involved in the bitter intensity. This finding is similar to the observations of taste intensity obtained from a human sensory study. Our results suggest the participation of hTAS2R39 in the detection of catechins in humans, indicating the possibility that bitterness of tea catechins can be evaluated by using cells expressing hTAS2R39

Dietary phytonutrients found in vegetables and fruit appear to lower the risk of cancer and cardiovascular disease. Studies on the mechanisms of chemoprotection have focused on the biological activity of plant-based phenols and polyphenols, flavonoids, isoflavones, terpenes, and glucosinolates. Enhancing the phytonutrient content of plant foods through selective breeding or genetic improvement is a potent dietary option for disease prevention. However, most, if not all, of these bioactive compounds are bitter, acrid, or astringent and therefore aversive to the consumer. Some have long been viewed as plant-based toxins. As a result, the food industry routinely removes these compounds from plant foods through selective breeding and a variety of debittering processes. This poses a dilemma for the designers of functional foods because increasing the content of bitter phytonutrients for health may be wholly incompatible with consumer acceptance. Studies on phytonutrients and health ought to take sensory factors and food preferences into account.


I need a scientist or chemist in the house....

1 comment:

Justin Simons said...

Interesting post/issue Tim. A quality piece of dark chocolate is another item with similar characteristics that may help clients understand complexity and the transformation of taste. Good to read another post!

 
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