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Wednesday, November 10, 2010

Chemistry Of Cooking - - - A Biochemist Explains The Chemistry Of Cooking

A biochemist and cook explains that cooking is all about chemistry and knowing some facts can help chefs understand why recipes go wrong. Because cooking is essentially a series of chemical reactions, it is helpful to know some basics. For example, plunging asparagus into boiling water causes the cells to pop and result in a brighter green. Longer cooking, however, causes the plant's cell walls to shrink and releases an acid. This turns the asparagus an unappetizing shade of grey.
 

You love to cook, but have you whipped up some disasters? Even the best recipes can sometimes go terribly wrong. A nationally recognized scientist and chef says knowing a little chemistry could help.

Long before she was a cook, Shirley Corriher was a biochemist. She says science is the key to understanding what goes right and wrong in the kitchen.

"Cooking is chemistry," said Corriher. "It's essentially chemical reactions."

This kind of chemistry happens when you put chopped red cabbage into a hot pan. Heat breaks down the red anthocyanine pigment, changing it from an acid to alkaline and causing the color change. Add some vinegar to increase the acidity, and the cabbage is red again. Baking soda will change it back to blue.

Cooking vegetables like asparagus causes a different kind of reaction when tiny air cells on the surface hit boiling water.

"If we plunge them into boiling water, we pop these cells, and they suddenly become much brighter green," Corriher said.

Longer cooking is not so good. It causes the plant's cell walls to shrink and release acid.

"So as it starts gushing out of the cells, and with acid in the water, it turns cooked green vegetables into [a] yucky army drab," Corriher said.

And that pretty fruit bowl on your counter? "Literally, overnight you can go from [a] nice green banana to an overripe banana," Corriher said.

The culprit here is ethylene gas. Given off by apples and even the bananas themselves, it can ruin your perfect fruit bowl -- but put an apple in a paper bag with an unripe avocado, and ethylene gas will work for you overnight.

"We use this as a quick way to ripen," Corriher said. Corriher says understanding a little chemistry can help any cook.

"You may still mess up, but you know why," she said. When it works, this kind of chemistry can be downright delicious.

WHAT ARE ACIDS AND BASES? An acid is defined as a solution with more positive hydrogen ions than negative hydroxyl ions, which are made of one atom of oxygen and one of hydrogen. Acidity and basicity are measured on a scale called the pH scale. The value of freshly distilled water is seven, which indicates a neutral solution. A value of less than seven indicates an acid, and a value of more than seven indicates a base. Common acids include lemon juice and coffee, while common bases include ammonia and bleach.

WHY DOES FOOD SPOIL? Processing and improper storage practices can expose food items to heat or oxygen, which causes deterioration. In ancient times, salt was used to cure meats and fish to preserve them longer, while sugar was added to fruits to prevent spoilage. Certain herbs, spices and vinegar can also be used as preservatives, along with anti-oxidants, most notably Vitamins C and E. In processed foods, certain FDA-approved chemical additives also help extend shelf life.



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Younger Brains Are Easier to Rewire -- Brain Regions Can Switch Functions

Younger Brains Are Easier to Rewire -- Brain Regions Can Switch Functions
A new paper from MIT neuroscientists, in collaboration with Alvaro Pascual-Leone at Beth Israel Deaconess Medical Center, offers evidence that it is easier to rewire the brain early in life. The researchers found that a small part of the brain's visual cortex that processes motion became reorganized only in the brains of subjects who had been born blind, not those who became blind later in life.

The new findings, described in the Oct. 14 issue of the journal Current Biology, shed light on how the brain wires itself during the first few years of life, and could help scientists understand how to optimize the brain's ability to be rewired later in life. That could become increasingly important as medical advances make it possible for congenitally blind people to have



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Cleaning Infected Blood - Biologists Develop Machine To Remove Viruses From Blood

infectious disease experts designed a machine called the hemopurifier. It works much like a dialysis machine, using thin fibers to capture and remove viruses from the blood it filters. The machine requires the drawing of blood through an artery, which is sent through a tube into the machine, then back into the body. It can treat a number of illnesses.

Every day, 14,000 people are infected with HIV, the virus that leads to AIDs. There's no cure, but now a breakthrough -- a machine that could clean blood, keeping more and more people alive longer.

"I remember lying in bed thinking, 'I am going to die. I'm going to die. I feel so sick.' And I remember thinking laying in that bed, 'And I know exactly what it is,'" HIV patient John Paul Womble, told Ivanhoe. HIV could kill Womble. He watched his father die from the virus and now he is living



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Mumbai Boy won a reality TV show to fund his dream stem cell research

Caezaan Keshvani is currently enrolled in university in New York, USA. Before he began his PhD programme at SUNY Upstate Medical University in Syracuse, he studied at University of Sheffield, UK. What made this all possible for this bright young man who had all but given up hope of ever studying abroad? Winning a reality television show.

Raised in Mumbai, Caezaan's story is a little different from the thousands of Indian students who head abroad each year. After completing his CIE A levels, he planned to head abroad to study. As he planned his next step, tragedy struck. His father, a doctor, was seriously injured in the train bomb blasts in Mumbai in 2006 and most of the family savings were used up for the multiple surgeries he had to undergo. As his study abroad hopes gradually dwindled, Caezaan learned of a reality show that offered the winner a 100-per cent



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Antibodies with More “Hang Time” May Give Researchers a Jump on New HIV Vaccine Strategy

Researchers are inching their way toward a new HIV vaccine strategy by studying the cells of people who have naturally—and bafflingly—strong immune defenses against the virus.

Last year, Howard Hughes Medical Institute investigator Michel C. Nussenzweig's team figured out how to isolate key immune cells from rare individuals who are HIV-positive but carry very low levels of the virus in their blood and have only mild, if any, symptoms.

That study found that these individuals produce a diverse army of antibodies—blood proteins that go after foreign invaders—to target HIV particles from multiple angles.

Now, the team has discovered that some of these so-called 'broadly neutralizing antibodies' are versatile in another way: a single antibody can bind to two structurally distinct sites on an HIV particle at once. The findings are published in the September 29, 2010 issue of the journal Nature.

Although neutralizing antibodies cannot cure HIV once an individual is infected, experiments in primates



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Mahantesh.I.B
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