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Tuesday, December 28, 2010

Tomato

Tomato

The tomato is a plant in the Solanaceae or nightshade family. The taxonomic name is eitherSolanum lycopersicum or Lycopersicon esculentum depending on the reference. Originating in South and Central America, the tomato is now grown world-wide for its brightly coloured (usually red, from the pigment lycopene) edible fruits. The word tomato derives from Náhuatltomatl 
Contents 

Pre-historytomatoes-red.jpg

The tomato is believed to have been first cultivated in ancient Peru, where several wild species of green tomatoes still grow. Then about three thousand years ago it was brought to Mexico. It is an offshoot of the Mexican lineage L. esculentum cerasiforme which is thought to be the direct ancestor of the modern tomato. The pottery of ancient Peruvian city-states do not appear to mention the tomato, this has led some botanists to conclude that the cultivation of the tomato was done in Mexico. However this is not conclusive as many other fruits in continuous cultivation in Peru are not present in the pottery. Also much horticultural knowledge was lost after the arrival of Europeans, and the Christian Church had a policy of burning all pagan books and quartering their keepers.

Early history


In the 16th and 17th centuries, many Europeans believed tomatoes were poisonous because of the plant's relationship to nightshade and tobacco, although they were grown as garden ornamentals.
The first traces of use of tomato as food date back to South Europe in the first half of the 18th century. Only in the second half of the 19th century cultivation of the tomato as food begins to be widespread, mainly in southern Italy and in France.
Vincenzo Corrado, a cook in the Neapolitan court, describes recipes with tomatoes in the bookIl cuoco galante, first edition 1773, adding more recipes with tomatoes in the 1819 edition.
In 1809, Nicolas Appert, a chef from Paris, published L'art de conserver le substances alimentaires d'origine animale et végétale pour plusieurs années, a book on food conservation where he deals also with preserving tomato.
Thomas Jefferson was a pioneer in growing tomatoes, beginning in 1809. He grew large ribbed "Spanish" tomatoes. Jefferson's daughters left numerous recipes that involved tomatoes, including gumbo soups, cayenne-spiced tomato soup, green tomato pickles, tomato preserves, and tomato omelettes. Tomatoes were purchased in 1806 for Presidential dinners. Randolph'sThe Virginia Housewife has seventeen recipes for tomatoes, including gazpacho, gumbo, and catsup. In an 1824 speech before the Albemarle Agricultural Society, Jefferson's son-in-law, Thomas Mann Randolph discussed the transformation of Virginia farming due to the introduction of new crops. He mentioned how tomatoes were virtually unknown ten years earlier, but by 1824 everyone was eating them because they believed they kept one's blood pure in the heat of summer."[1]
The following story is widely cited, but there are doubts by many historians that it ever happened. Some lingering doubts about the safety of the tomato in the United States were largely put to rest in 1820, when Colonel Robert Gibbon Johnson announced that at noon onSeptember 28, he would eat a basket of tomatoes in front of the Salem, New Jerseycourthouse. Reportedly, a crowd of more than 2,000 persons gathered in front of the courthouse to watch the poor man die after eating the poisonous fruits, and were shocked when he lived.

Modern uses of tomatoes

Tomatoes are now eaten freely in Europe as well as in the rest of the world; in fact, periodically since their exoneration, they have been esteemed as a purported aphrodisiac. Today, their consumption is believed to benefit the heart.
Lycopene, one of nature's most powerful antioxidants, is present in tomatoes and has been found to be beneficial in preventing prostate cancer, among other things.
Botanically a berry, the tomato is generally thought of and used as a vegetable: it's more likely to be part of a sauce or a salad than eaten whole as a snack, let alone as part of a dessert (though, depending on the variety, they can be quite sweet, especially roasted).
Tomatoes are used extensively in Mediterranean and Middle Eastern cuisines, especially Italianones. The tomato has an acidic property that is used to bring out other flavors. This same acidity makes tomatoes especially easy to preserve in home canning as tomato sauce or paste.Tomato juice is often canned and sold as a beverage. Unripe green tomatoes can also be used to make salsa, or they can be batter-dipped and fried.
The town of Buñol, Spain annually celebrates La Tomatina, a festival centered on an enormous tomato fight. Tomatoes are also a popular "non-lethal" throwing weapon in mass protests, and there is a common tradition of throwing rotten tomatoes at bad actors or singers on a stage.

Controversies


Fruit or vegetable?

Botanically speaking a tomato is the ovary, together with its seeds, of a flowering plant. This would mean that technically it would be considered a fruit. However, speaking from a culinary perspective the tomato is typically served as or part of a main course of a meal meaning that it would be considered a vegetable. This argument has lead to actual legal implications in the United States. In 1887, U.S. tariff laws which imposed a duty on vegetables but not on fruits caused the tomato's status to become a matter of legal importance. The U.S. Supreme Courtsettled this controversy in 1893, declaring that the tomato is a vegetable, along withcucumberssquashesbeans, and peas, using the popular definition which classifies vegetables by use: they are generally served with dinner and not dessert. The case is known as Nix v. Hedden
In concordance with this classification, the tomato is the state vegetable of New Jersey

The pronunciation conundrum

In some English speaking countries, the pronunciation of tomato is in dispute: it can either be pronounced to-MAY-to or to-MAH-to. The difference is inherent in the dialects: British Englishspeakers typically favor to-MAH-to, while American English speakers have a tendency to say to-MAY-to. The word's multiple pronunciations were immortalized in song in Gershwin's 1937 song,Let's Call the Whole Thing Off (You say to-may-to and I say to-mah-to / you say po-tay-to and I say po-tah-to), and have become a symbol for nitpicking pronunciation disputes. In this capacity it has even become an American slang term: saying "to-may-to, to-mah-to" when presented with two choices can mean "what's the big deal, there's no real difference."

Proper storage

Many people believe that tomatoes should be stored refrigerated. This actually destroys the flavor and texture. Ideally tomatoes should be stored between 55–65°F (13–18°C) at 80–95% relative humidity.

Picking and ripening

Tomatoes sold in American grocery stores are often picked unripe, and ripened in storage withethylene. Ethylene is the plant hormone produced by many fruits and acts as the cue to begin the ripening process. These tend to keep longer — but have poorer flavor and a mealier, starchier texture than tomatoes ripened on the plant. They may be recognized by their color, which is more pink or orange than the ripe tomato's deep red.
Recently, stores have begun selling "tomatoes on the vine" which are ripened still connected to a piece of vine. These tend to be much more flavorful (at a price premium) than artificially-ripened tomatoes, but still may not be the equal of local garden produce.
Also relatively recently, slow-ripening varieties of tomato have been developed by crossing a non-ripening variety with ordinary tomato varieties. Varieties were selected whose fruits have a long shelf life and at least reasonable flavor

Bananas Are Radioactive

Kevin Rosseel, morguefile.comHomework Helpers: Chemistry
Did you know bananas are slightly radioactive? Bananas contain high levels of potassium. Radioactive K-40 has an isotopic abundance of 0.01% and a half-life of 1.25 billion years. The average banana contains around 450 mg of potassium and will experience about 14 decays each second. It's not something you need to worry about, since 0.01% of the potassium already in your body is K-40, plus the element is essential for proper nutrition. If you have a banana for your lunch you aren't going to set off a Geiger counter. If you carry a produce truck full of them, then you might have a noticeable radiation signature. The same is true if you are carrying a lot of potatoes or potassium fertilizer.

Friday, December 3, 2010

H2O

Water is, in fact, a chemical. Its chemical formula is H2O (or, less 
commonly, HOH), which is what this website is named after. H2O is 
also one of the most well-known chemical formulas. When properly 
written, the "2" after the H is written in subscript (as you can see in the 
banner above), but due to formatting restrictions it will simply be 
written as "H2O" on this website.

What does H2O mean? Each water molecule is made of two hydrogen 
atoms and one oxygen atom, thus there are two "H" atoms and one 
"O". The atoms are joined by covalent bonding, meaning that they 
share electrons (as opposed to ionic bonding, in which atoms 
completely transfer electrons). On the right is an image of water's 
molecular structure.

Water is the most abundant molecule on Earth. Approximately 70% of 
the Earth's surface is water. Water is also the only substance on Earth 
which naturally occurs in a solid, liquid and gas form.
The Celsius temperature scale is based on waters' freezing point (0 
degrees) and boiling point (100 degrees). Unlike most substances, 
water's solid from is less dense than its liquid form - this is why ice 
cubes will float in your drinks. Water is also capable of absorbing a lot 
of heat before its temperature increases; thus it is used in things such 
as a radiator coolant in cars.

Water has a high surface tension. This is why some bugs like water 
striders (of the Gerridae family) can walk on water - because they weigh 
less than the surface tension of the water. Due to the shape of a water 
molecule, molecules stick and clump together to form this high 
tension (the two lighter hydrogen atoms in the image on the right 
could attach to the oxygen atom of another water molecule, and so 
forth). That's why water comes together in the form of drops - if it wasn't 
for gravity water would attach together in a spherical shape.

Tuesday, November 30, 2010

Citric acid

Citric acid

Properties
General
NameCitric acid
image:citricacidstructure.png
Chemical formulaC6H8O7
Formula weight192.13 amu
Synonyms2-hydroxy-1,2,3-propanetricarboxylic acid
CAS number77-92-9
Phase behavior
Melting point426 K (153 °C)
Thermal decomposition temperature448 K (175°C)
Acid-base properties
pKa13.15
pKa24.77
pKa35.19
Solid properties
ΔfH0-1543.8 kJ/mol
S0252.1 J/mol·K
Cp226.5 J/mol·K
Density1.665 ×103 kg/m3
Safety
Acute effectsSkin and eye irritant.
Chronic effectsNone.
More info
PropertiesNIST WebBook
MSDSHazardous Chemical Database
SI units were used where possible. Unless otherwise stated, standard conditions were used.
Citric acid is a weak organic acid found in citrus fruits. It is a good, naturalpreservative and is also used to add an acidic (sour) taste to foods and soft drinks. In biochemistry, it is important as an intermediate in the citric acid cycle and therefore occurs in the metabolism of almost all living things. It also serves as an environmentally friendly cleaning agent and acts as an antioxidant.
Citric acid exists in a variety of fruits and vegetables, but it is most concentrated inlemons and limes, where it can comprise as much as 8% of the dry weight of the fruit.
Citric acid's chemical formula is C6H8O7 and its structure is shown at right. This structure is reflected in its IUPAC name 2-Hydroxy-1,2,3-propanetricarboxylic acid.
Contents [hide]

Properties

The physical properties of citric acid are summarized in the table at right. The acidity of citric acid results from the three carboxy groups COOH which can lose aproton in solution. If this happens, the resulting ion is the citrate ion. Citrates make excellent buffers for controlling the pH of acidic solutions.
Citrate ions form salts called citrates with many metal ions. An important one iscalcium citrate or "sour salt", which is commonly used in the preservation and flavoring of food. Additionally, citrates can chelate metal ions, which gives them use as preservatives and water softeners.
At room temperature, citric acid is a white crystalline powder. It can exist either in an anhydrous (water-free) form, or as a monohydrate that contains one water molecule for every molecule of citric acid. The anhydrous form crystallizes from hot water, while the monohydrate forms when citric acid is crystallized from cold water. The monohydrate can be converted to the anhydrous form by heating it above 74°C.
Chemically, citric acid shares the properties of other carboxylic acids. When heated above 175°C, it decomposes through the loss of carbon dioxide and water.

History

The discovery of citric acid has been credited to the 8th century Islamic alchemistJabir Ibn Hayyan (Geber). Medieval scholars in Europe were aware of the acidic nature of lemon and lime juices; such knowledge is recorded in the 13th centuryencyclopedia Speculum Majus (The Great Mirror), compiled by Vincent of Beauvais. Citric acid was first isolated in 1784 by the Swedish chemist Carl Wilhelm Scheele, who crystallized it from lemon juice. Industrial-scale citric acid production began in 1860, based on the Italian citrus fruit industry.
In 1893, C. Wehmer discovered that Penicillium mold could produce citric acid fromsugar. However, microbial production of citric acid did not become industrially important until World War I disrupted Italian citrus exports. In 1917, the Americanfood chemist James Currie discovered that certain strains of the mold Aspergillus niger could be efficient citric acid producers, and Pfizer began industrial-level production using this technique two years later.

Production

In this production technique, which is still the major industrial route to citric acid used today, cultures of Aspergillus niger are fed on sucrose to produce citric acid. After the mold is filtered out of the resulting solution, citric acid is isolated by precipitating it with lime (calcium hydroxide) to yield calcium citrate salt, from which citric acid is regenerated by treatment with sulfuric acid.
Alternatively, citric acid is sometimes isolated from the fermentation broth byextraction with a hydrocarbon solution of the organic base trilaurylamine , followed by re-extraction from the organic solution by water.

Uses

Most citric acid is used as a flavoring and preservative in food and beverages, especially soft drinks; it is denoted by E Number E330. Citrate salts of various metals are used to deliver those minerals in a biologically available form in many dietary supplements. The buffering properties of citrates are used to control pH in household cleaners and pharmaceuticals.
Citric acid's ability to chelate metals gives it use in soaps and laundry detergents. By chelating the metals in hard water, it lets these cleaners produce foam and work better without need for water softening. Similarly, citric acid is used to regenerate the ion exchangematerials used in water softeners by stripping off the accumulated metal ions as citrate complexes.
It is used in the biotechnology and pharmaceutical industry to passivate high purity process piping in lieu of using nitric acid, since nitric is a hazardous disposal issue once it is used for this purpose, while citric is not.
In the United Kingdom, pharmacies control the sale of Citric acid. Citric acid is a popular buffer used to increase the solubility of streetheroin in Scotland. Single-use citric acid sachets have been used as an inducement to get heroin users to exchange their dirty needles for clean needles in an attempt to decrease the spread of AIDS and hepatitis. See the .pdf article here. Other acidifiers used for brown heroin are ascorbic acid, acetic acid, and lactic acid: in their absence, the drug abuser will often substitute lemon juice or vinegar.

Safety

Citric acid is recognized as safe for use in food by all major national and international food regulatory agencies. It is naturally present in almost all forms of life, and excess citric acid is readily metabolized and eliminated from the body.
Contact with dry citric acid or with concentrated solutions can result in skin and eye irritation, so protective clothing should be worn when handling these materialsSugo Music Free Holiday Sampler

Why Are Babies Born with Blue Eyes?

Question: Why Are Babies Born with Blue Eyes?
Answer: You inherit your eye color from your parents, but no matter what the color is now, it may have been blue when you were born. Why? Melanin, the brown pigment molecule that colors your skin, hair, and eyes, hadn't been fully deposited in the irises of your eyes or darkened by exposure to ultraviolet light. The iris is the colored part of the eye that controls the amount of light that is allowed to enter. Some other animals are born with blue eyes, too, such as kittens.
Melanin is a protein. Like other proteins, the amount and type you get is coded in your genes. Irises containing a large amount of melanin appear black or brown. Less melanin produces green, gray, or light brown eyes. If your eyes contain very small amounts of melanin, they will appear blue or light gray. People with albinism have no melanin in their irises and their eyes may appear pink because the blood vessels in the back of their eyes reflect light.
Melanin production generally increases during the first year of a baby's life, leading to a deepening of eye color. The color is often stable by about 6 months of age. However, several factors can affect eye color, including use of certain medications and environmental factors. Some people experience changes in eye color over the course of their lives. People can have eyes of two colors. Even the genetics of eye color inheritance isn't as cut-and-dried as was once thought, as blue-eyed parents have been known (rarely) to have a brown-eyed child!

Friday, November 26, 2010

How To Make a Rainbow in a Glass Density Demonstration

You don't have to use lots of different chemicals to make a colorful density column. This project uses colored sugar solutionsmade at different concentrations. The solutions will form layers, from least dense, on top, to most dense (concentrated) at the bottom of the glass.
This project forms nice layers. Try to avoid gel food colorings. 
Difficulty: 
Easy
Time Required: minutes

Here's How:

  1. Line up five glasses. Add 1 tablespoon (15 g) of sugar to the first glass, 2 tablespoons (30 g) of sugar to the second glass, 3 tablespoons of sugar (45 g) to the third glass, and 4 tablespoons of sugar (60 g) to the fourth glass. The fifth glass remains empty.
  2. Add 3 tablespoons (45 ml) of water to each of the first 4 glasses. Stir each solution. If the sugar does not dissolve in any of the four glasses, then add one more tablespoon (15 ml) of water to each of the four glasses.
  3. Add 2-3 drops of red food coloring to the first glass, yellow food coloring to the second glass, green food coloring to the third glass, and blue food coloring to the fourth glass. Stir each solution.
  4. Now let's make a rainbow using the different density solutions. Fill the last glass about one-fourth full of the blue sugar solution.
  5. Carefully layer some green sugar solution above the blue liquid. Do this by putting a spoon in the glass, just above the blue layer, and pouring the green solution slowly over the back of the spoon. If you do this right, you won't disturb the blue solution much at all. Add green solution until the glass is about half full.
  6. Now layer the yellow solution above the green liquid, using the back of the spoon. Fill the glass to three-quarters full.
  7. Finally, layer the red solution above the yellow liquid. Fill the glass the rest of the way.

Tips:

  1. The sugar solutions are miscible, or mixable, so the colors will bleed into each other and eventually mix.
  2. If you stir the rainbow, what will happen? Because this density column is made with different concentrations of the same chemical (sugar or sucrose), stirring would mix the solution. It would not un-mix, like you would see with oil and water.
  3. Try to avoid using gel food colorings. As you can see in my photo, it is difficult for young children to mix them into the solution.
  4. If your sugar won't dissolve, an alternative to adding more water is to nuke the solutions for about 30 seconds in the microwave or to use warm water in the first place. If you heat the water, use care to avoid burns.
  5. If you want to make layers you can drink, try substituting unsweetened soft drink mix for the food coloring, or four flavors of sweetened mix for the sugar plus coloring.

What You Need:

  • sugar
  • water
  • food coloring
  • tablespoon
  • 5 glasses or clear plastic cups