-GT2910.S3 2008

Henry J. Klaunberg biological

Kristin Surak 2012

-Gt2910.T2978

·      The chemicals responsible for these sensations are actually toxic.

·      Example: purified essence of oregano and thyme can damage skin and lungs; this is their primary function.

·      The plants produce these chemicals to be irritating to animals or microbes and is a source of protection.

·      The volatility gives them the advantage of counterattacking through the air.

·      Some animals will be deterred by smell alone.

·      Herbs and spices can be made nontoxic through the principle of cooking and dilution

·      Eating a whole oregano leaf vs. small amounts diffused through a whole dish.

·      Aroma chemicals are more similar to oils and fats than they are to water, and therefore are more soluble in oil then they are in water

·      Cooks make flavor extracts by infusing herbs in watery vinegar and in alcohols but both alcohol and vinegar’s acetic acid are small cousins of fat molecules and help dissolve more aromatics than plain water could.

·      The defensive aroma chemicals can have disruptive effects on a plant’s own cells as well as on predators, so plants take care to isolate them from their inner workings.

·      Plants stockpile their aroma chemicals in specialized oil-storage cells, in glands on the leaves, or in channels that open up between cells.

·      Plants usually create a mixture of defensive terpenes.

·      They are characteristic of the needles and bark of coniferous trees, citrus fruits, flowers, and herbs and spices.

·      Terpenes tend to be volatile and reactive. They are often the first molecules to reach the nose

Terpene found in the aromatic qualities of Oolong

Terpene found in the aromatic qualities of Oolong

·      It is an alkaloid -à what is an alkaloid?

·      Continued notes below…

·      Almost all known alkaloids are poisonous at high doses

·       Any of a class of nitrogenous organic compound of plant origin that have pronounced physiological actions on humans. They include many drugs (morphine, quinine) and poisons (atropine, strychnine).

·      Caffeine stimulates the central nervous system

·      Relieves drowsiness and fatigue

·      Quickens reaction time

·      Reaches its maximum levels in the blood between 15 minutes and two hours after consumption. Levels are reduced by half within three to seven hours. It’s effects are more noticeable in people who don’t normally consume it.

·      Aromatic molecules are locked up in nonvolatile combinations with sugar molecules

·      Green tea retains many of the qualities of the fresh leaf

·      Oolong and Red/Black Tea, rely on enzyme transformation

·      Turns defensive materials into delightful molecules.

·      There are two general enzymatic transformation for tea

1.     Liberation of aroma molecules which, are bound up with sugars and can’t escape into the air

2.     Building large molecules from small ones. There by modifying the flavor, color, and body. The small molecules are the tea leaf’s abundant supply of three-ring phenolic compounds, which are astringent, bitter and colorless. The leaf’s browning enzyme, polyphenoloxidase uses oxygen form the air to join the small phenolic molecules together to form the larger complexes.

·      A combination of two phenolics give a kind of molecule, Theaflavin, which contributes to yellow and light copper and is less bitter and astringent.

·      Complexes of three to ten of the original phenolics are orange-red and, and less astringent and are called thearubigens

·      The largest complexes are brown and not astringent at all and are called theaflavin digallate

·      The longer the tea leaves are rolled (hand rolled or by machine) withered (allowed to sit out in the heat or a heat controlled room) and not heated to halt the enzyme (polyphenoloxidase) the less bitter and astringent and the more colored the tea leaves will become.

·      In Oolong tea half of the small phenolics have been transformed

·      Black Teas 85%

·      Tea is mildly acidic and bitter; It also has trace amounts of salt

·      Rich in amino acid, theanine, which itself is sweet and savory and partly breaks down into glutamic acid.

·      Chinese green teas also contain synergizers of savoriness (GMP) Monosodium glutemate and (IMP) Inosine monophosphate

·      Monosodium glutemate is usually known as MSG, and when made artificially, and used as artificial flavoring, has a lot of stigma attached to it.

·      Bitter caffeine and astringent phenolics bond to and take the edge off each other to produce the impression of a stimulating but usually not harsh body. (especially important to the taste of red/black teas)

·      Green tea pan fried (savory toasty notes

·      Oolong and Red/Black tea (floral, sweet, earthy)

·      600 volatiles have been identified in black tea

·      In the West: a relatively small amount of loose leaf tea, about a teaspoon, or a tea bag, per 6-oz cup is brewed once, for several minutes, then discarded.

·      In Asia: a larger quantity of leaves of any tea-as much as a third of the volume of the container- is first rinsed with hot water, then infused briefly several times. This style allows the drinker to enjoy the following infusions changing flavor and aroma gradually.

·      The infusion time depends on two favors. One is leaf size; small particles and their great surface area require less time for their contents to be extracted. The second is water temperature. The water temperature will depend on the type of tea being brewed.

·      Oolong and Black tea are typically brewed at a temperature close to boil, and briefly.

·      Green tea is infused longer in cooler water, 160-110 degrees F, which limits extraction of the abundant bitter and astringent phenolics and minimizes the damage to the chlorophyll which gives it its vibrant green pigment.

·      In a typical 3-5 minute infusion of black tea, about 40% of the leaf solids are extracted into the water.

·      Caffeine is rapidly extracted and more than three quarters of the total in the first 30 seconds. When preparing tea the Chinese way after the tea is washed a lot of the caffeine is discarded. The larger phenolic complexes come out more slowly.

·      The tea will be best consumed after being freshly brewed. The aroma will dissipate and their phenolic components react with dissolved oxygen and with each other; this changes the color and taste over time.

·      Some cultures mix their tea with milk. When the milk and tea are combined the phenolic compounds immediately bind to the milk proteins, become unavailable to bind to the mouth surfaces and the taste becomes less astringent. (it is best to mix hot tea to warm milk, rather than vice versa, because the milk will then be heated gradually avoiding a curdling reaction.

·      Lemon juice is sometimes added to tea to bolster its tartness and add the fresh citrus note. It will lighten the color of red/black tea by changing the structure of the red phenolic complexes (the complexes are weak acids themselves and take up hydrogen ions from lemon juice). Alkaline brewing water, conversely tends to produce blood-red infusions from black tea, and can make green tea red.