Several types of wheat are grown today. They differ in their protein content and growing habit.
The most common species of bread wheat is Triticum aestivum. This wheat is high in protein and forms a strong gluten. Most of the wheat produced in North America is Hard wheat, which constitutes 75% of the total crop. Soft wheat makes up 20% and have less protein and form weaker gluten. Durum wheat is a different species that is mainly used to make pasta.
The classification of wheat growth habits and kernel color. Spring wheats are sown in spring and harvested in fall. Winter wheats are sown in the fall and harvested in summer. Red wheat gets its color from the presence of phenolic compounds, which the White wheat variety lacks, and it is often preferred for its sweeter taste.
Showing posts with label phenolics. Show all posts
Showing posts with label phenolics. Show all posts
Saturday, March 31, 2012
Monday, March 19, 2012
Coffee
Coffee trees are native to Africa. They produce a red berry that contains two large seeds or "beans." The history of roasted coffee dates back to the 14th century Arab nations. From then, the coffee tree was taken to India in the 1600s, after which it was taken to Java and then to the French Caribbean. Today Brazil, Vietnam, and Colombia are the largest exporters of coffee.
There are two main trees that produce coffee beans: Coffea arabica, native to the Sudan, produces "arabica" beans; and Coffea canephora, native to West Africa, produces "robusta" beans. About 2/3 of the beans in the international trade are arabica beans. They develop a more complex and balanced flavor than robustas. They also contain less caffeine, less phenolic material, and more oil and sugar. Robustas are only popular because the trees themselves are more disease resistant.
There are two main trees that produce coffee beans: Coffea arabica, native to the Sudan, produces "arabica" beans; and Coffea canephora, native to West Africa, produces "robusta" beans. About 2/3 of the beans in the international trade are arabica beans. They develop a more complex and balanced flavor than robustas. They also contain less caffeine, less phenolic material, and more oil and sugar. Robustas are only popular because the trees themselves are more disease resistant.
Brewing tea
The quality of brewed tea and coffee is highly influenced by the water used to make them. Very hard water can slow flavor extraction, whereas soft water overextracts flavor and tends to have a salty flavor. Distilled water makes flat brews. The ideal water has moderate mineral content and a neutral pH. The final brew has an acidic pH around 5 that supports and balances flavors the best.
Many cities intentionally alkalinize water to reduce pipe corrosion. Alkalinity reduces the quality of flavor of both tea and coffe. Alkaline brews tend to produce red infusions from both, black and green, tea. Alkaline tap water can be corrected by adding tiny pinches of cream of tartar until it just begins to have a slightly tart taste.
Teas are brewed in various ways depending on the type of tea and the regional preference of the brewer. In the West, a small amount of tea is brewed once for several minutes, then discarded. In Asia, a greater quantity of tea leaves is used per ounces of liquid. It is rinsed with hot water and then infused several times. The temperature of water also varies. For black and oolong teas, use water close to boil, and infuse briefly. Green tea is infused longer and at lower temperatures, around 110-160 degrees F/45-70 degrees C. This limits too much extraction of the bitter phenolics and minimizes damage to the chlorophyll pigment.
The typical 5 minute brew of black tea extracts almost all of the caffeine present.
Once tea is properly brewed, it should be separated from the leaves to stop further extraction. Tea is best when drunk fresh. With time the aroma dissipates and phenolic compounds react with oxygen and each other, causing a change in color and taste.
If milk is to accompany the tea, it is best to add hot tea to warm milk to prevent the milk from curddling. The taste of tea with milk is milder because phenolic compounds bind to milk proteins and render them unable to bind to salivary proteins in the mouth.
Lemon juice is sometimes added to tea. The acidity of the lemon alters the structure of red phenolic complexes in black tea so it lightens the brew.
Many cities intentionally alkalinize water to reduce pipe corrosion. Alkalinity reduces the quality of flavor of both tea and coffe. Alkaline brews tend to produce red infusions from both, black and green, tea. Alkaline tap water can be corrected by adding tiny pinches of cream of tartar until it just begins to have a slightly tart taste.
Teas are brewed in various ways depending on the type of tea and the regional preference of the brewer. In the West, a small amount of tea is brewed once for several minutes, then discarded. In Asia, a greater quantity of tea leaves is used per ounces of liquid. It is rinsed with hot water and then infused several times. The temperature of water also varies. For black and oolong teas, use water close to boil, and infuse briefly. Green tea is infused longer and at lower temperatures, around 110-160 degrees F/45-70 degrees C. This limits too much extraction of the bitter phenolics and minimizes damage to the chlorophyll pigment.
The typical 5 minute brew of black tea extracts almost all of the caffeine present.
Once tea is properly brewed, it should be separated from the leaves to stop further extraction. Tea is best when drunk fresh. With time the aroma dissipates and phenolic compounds react with oxygen and each other, causing a change in color and taste.
If milk is to accompany the tea, it is best to add hot tea to warm milk to prevent the milk from curddling. The taste of tea with milk is milder because phenolic compounds bind to milk proteins and render them unable to bind to salivary proteins in the mouth.
Lemon juice is sometimes added to tea. The acidity of the lemon alters the structure of red phenolic complexes in black tea so it lightens the brew.
Sunday, March 18, 2012
Tea styles
Though there are many styles of tea, the following three account for most of the world consumption:
Green tea preserves some of the original qualities of the fresh leaf. It is made by cooking fresh or briefly withered leaves to inactivate their enzymes, then pressing them to release moisture, and finally drying them via hot air or a hot pan. "Pan firing" gives tea a characteristic aroma of roasted foods. In Japan, the leaves are steamed, so they have a more grassy flavor and green color.
Oolong tea is made by allowing modest enzyme transformation. The leaves are significantly withered, then lightly agitated and bruised. Enzymatic action occurs during the subsequent rest period, usually a few hours long. Once the bruised edges turn red, the leaves are pan-fired at high temperatures. The tea is rolled and dried at moderate temperatures, which gives it a light amber color and fruitful aroma.
Black tea undergoes profound enzymatic transformation. The leaves are withered for hours, rolled repeatedly, and air-dried at around 100 degrees Celsius. The tea develops a deep, dark color.
Other teas tend to be variations or additions to one of the above mentioned styles. For example, white tea is a version of Chinese green tea made almost exclusively from buds that are steamed and dried. Scented teas tend to be Chinese teas held for 8-12 hrs in containers with flowers such as jasmine, cassia bud, rose, orchid, and gardenia. They may include 1-2% flower petals. Other teas vary in the type of heat they receive, such as wood fires, or high temperature roasting.
Herbal tea, also known as herbal tisane, is made from ingredients other than the Camellia sinensis plant. There are three main categories: rooibos tea is primarily made from the South African red bush; mate tea is made from the South American Yerba Mate plant; and finally, herbal infusions are made from spices, fruits, flowers, or a variety of other plants.
Iced tea, the most popular form of tea in the US, is made from any kind of tea that is brewed and cooled. Black tea is most commonly brewed for iced tea. It was introduced by Richard Blechynden, a tea plantation owner who, in an attempt to promote his tea during the summer time, threw ice cubes in the mix and had people sample it during the 1904 World's Fair in St. Louis. Rapid cooling from ice makes the brewed black tea cloudy as caffeine and theaflavin compounds complex and precipitate out. To avoid this, brew the tea at room temperature or colder over several hours. The long process extracts less caffeine and theaflavin, so when chilled, they do not complex and the liquid remains clear. Iced tea is often sweetened or flavored.
Green tea preserves some of the original qualities of the fresh leaf. It is made by cooking fresh or briefly withered leaves to inactivate their enzymes, then pressing them to release moisture, and finally drying them via hot air or a hot pan. "Pan firing" gives tea a characteristic aroma of roasted foods. In Japan, the leaves are steamed, so they have a more grassy flavor and green color.
Oolong tea is made by allowing modest enzyme transformation. The leaves are significantly withered, then lightly agitated and bruised. Enzymatic action occurs during the subsequent rest period, usually a few hours long. Once the bruised edges turn red, the leaves are pan-fired at high temperatures. The tea is rolled and dried at moderate temperatures, which gives it a light amber color and fruitful aroma.
Black tea undergoes profound enzymatic transformation. The leaves are withered for hours, rolled repeatedly, and air-dried at around 100 degrees Celsius. The tea develops a deep, dark color.
Other teas tend to be variations or additions to one of the above mentioned styles. For example, white tea is a version of Chinese green tea made almost exclusively from buds that are steamed and dried. Scented teas tend to be Chinese teas held for 8-12 hrs in containers with flowers such as jasmine, cassia bud, rose, orchid, and gardenia. They may include 1-2% flower petals. Other teas vary in the type of heat they receive, such as wood fires, or high temperature roasting.
Herbal tea, also known as herbal tisane, is made from ingredients other than the Camellia sinensis plant. There are three main categories: rooibos tea is primarily made from the South African red bush; mate tea is made from the South American Yerba Mate plant; and finally, herbal infusions are made from spices, fruits, flowers, or a variety of other plants.
Iced tea, the most popular form of tea in the US, is made from any kind of tea that is brewed and cooled. Black tea is most commonly brewed for iced tea. It was introduced by Richard Blechynden, a tea plantation owner who, in an attempt to promote his tea during the summer time, threw ice cubes in the mix and had people sample it during the 1904 World's Fair in St. Louis. Rapid cooling from ice makes the brewed black tea cloudy as caffeine and theaflavin compounds complex and precipitate out. To avoid this, brew the tea at room temperature or colder over several hours. The long process extracts less caffeine and theaflavin, so when chilled, they do not complex and the liquid remains clear. Iced tea is often sweetened or flavored.
Making tea - an enzymatic transformation
The fresh tea leaf has a bitter and astringent taste due to the abundant phenolic substances present. Aromatic molecules are locked up in nonvolatile compounds with sugar. The key to making tea is encouraging the leaf's own enzymes to transform these austeric molecules into pleasant ones.
The best tea is made from a plant's young shoots and unopened leaf buds as they contain the highest concentration of phenolic compounds and related enzymes. These young leaves are harvested and allowed to wither. Withering causes a shift in their metabolism that accounts for a change in flavor and physical fragility. The fragile leaves are rolled or pressed to break down tissue structures that contain cell fluids. Enzymes spill, react with oxygen, and break the aroma-sugar complexes apart. Simple phenolic compounds such as catechin react into larger compounds. The browning enzyme, polyphenoloxidase, uses oxygen to join small phenolic molecules into large complexes that are brown and not astringent at all. The deep, complex of tea is developed by this enzymatic transformation, often referred to as "fermentation," even though no significant microbial activity is involved.
Once the desired flavor is developed, the leaves are heated to inactive their enzymes. Furthermore, dry heat is used to develop different depths of flavor and to preserve leaves for long keeping. The dry leaves are sieved and graded, and prepared for packaging and consumption.
The best tea is made from a plant's young shoots and unopened leaf buds as they contain the highest concentration of phenolic compounds and related enzymes. These young leaves are harvested and allowed to wither. Withering causes a shift in their metabolism that accounts for a change in flavor and physical fragility. The fragile leaves are rolled or pressed to break down tissue structures that contain cell fluids. Enzymes spill, react with oxygen, and break the aroma-sugar complexes apart. Simple phenolic compounds such as catechin react into larger compounds. The browning enzyme, polyphenoloxidase, uses oxygen to join small phenolic molecules into large complexes that are brown and not astringent at all. The deep, complex of tea is developed by this enzymatic transformation, often referred to as "fermentation," even though no significant microbial activity is involved.
Once the desired flavor is developed, the leaves are heated to inactive their enzymes. Furthermore, dry heat is used to develop different depths of flavor and to preserve leaves for long keeping. The dry leaves are sieved and graded, and prepared for packaging and consumption.
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