Tag Archives: Antioxidant

Why lobsters and Crabs turn red on cooking……..

Popular Food

Lobsters and Crabs are the two Sea foods are mouthwatering and popular all over the world. So much so that fairs are held to celebrate the lobster.  One such festival is held in Rockland, Maine which is attended by thousands.


Cooking Chemistry

When cooked these creatures turn coppery red. Although it is not necessary to become a chemist to become chefs but cooking is a science where chemistry takes place at each step. Some chemicals break down to get converted into edible and easily digestible form. Similarly in many foods there are color changes when cooked which is also due to chemical modification of ingredients. Here also, chemistry is occurring.

Normal lobster is of muddy color when alive. But the final color is dependent on the amounts of a pigment called astaxanthin which is also the pigment responsible for the red color of carrots, pink of flamingos, salmon and crabs. This pigment is red in color when free. It’s chemical structure is given below.

Due to the ketone and alcohol groups this compound is very active chemically easily binds other chemicals like proteins. Pigment is a powerful antioxidant. Lobsters ingest it to keep stress of survival under control has been found be beneficial human beings.

What happens in the lobster is that this pigment binds to the proteins in its skin. Due to this binding, it is forced to change its geometric structure and gets twisted to fit in. Depending on the type of protein it bonds to, there’s either what’s called a bathochromic shift, which turns the pigment blue, or a hypsochromic shift, to yellow. When you’re looking at a lobster, you’re seeing light reflecting through different layers of free and bonded astaxanthin–a lot of colors mixed together, hence the muddy brown.

So the final color is a combination of many colors like red, blue and amount and type  of proteins present in the body of lobster and the age . The muddy color is good for camouflaging from the predator because it becomes indistinguishable from the muddy water.

When the lobster is cooked the proteins are denatured and release the astaxanthin pigment turning the cooked meat into coppery red.


Revival of Govardhan Parvat: The Mountain Moved by Krishna

In our country where mythology plays a big role in the lives of its inhabitants, many sites like hills, rivers, and caves have their associations with the mythology. One such concerns the Lord Krishna and is called Govardhan Parvat (mountain).

The legend is that when the uninterrupted deluge threatened to innundate Mathura, Krishna lifted the entire mountain on his little finger to make an umbrella to protect the Mathura.

UP government has planned to revive the almost barren Govardhan parvat situated about 23 kilometres from Mathura. Government plans to plant the herbal plants on the mountain. These are:

Kadamba: It is a tropical tree. Krishna and Radha are said to have conducted their love play under the cool shade of the tree. It is used as one of the raw materials in the preparation of “itars”.

Tamala or Indian bayleaf or tezpatta: It is commonly used in Indian culinary as well as medicines particularly for alleviation of diabetes due to the presence of highly antioxidant enzymes.

Karira: Scientific name is Capparis decidua. It’s spicy fruits are used for culinary purposes like vegetable, curries, and pickles. It is also used in medicine.

Pakar : It belongs to mulberry family. Leaves have sour taste.

Pilkhan: Scientific name Ficus virens. It grows to heights of about 100 feet. It is Avenue tree. It bears “strangler figs” because they can germinate on other trees and strangle them. It is used in Thai cuisine.

Tri-Phenyl Methyl: The Radical which can be bottled

Most of the reactions in the organic chemistry the formation of short lived radicals or carbonium ions. They are the highly reactive. Element Carbon, the element about which the whole branch of organic chemistry revolves, has 4 valency and thus forms 4 single covalent bonds. It has got 4 unpaired electrons in the sp3 configuration which means that 4 equivalent hybrid orbitals are formed by combination of 1s and three 3p orbitals in the second shell.

During many reactions, one unpaired electrons remains when 1 atom attached to carbon is ripped off. This is of the form R3C. where R are alkyl groups. This is a radical and is extremely reactive and seeks to stabilize itself by combining with another atom with 1 unpaired electron. These radicals thus live for very short time during the steps of organic reactions. Sometimes their existence seems to be a fable.

But then, there was a very brilliant Russian organic chemist. His name was Gomberg. Still a student, he wanted to substitute all the hydrogen atoms on the methane and ethane with bulky C6H5 phenyl groups. No one had done this before. He did many experiments and after excluding oxygen from his experiments he was able to prepare the first stable radicals ever found in organic chemistry.

This was tri-phenyl methyl radical. Its solution when oxygen was blanketed have slightly yellow color which intensified upon warming. As we have said that radicals try to combine with other atoms with unpaired electrons. The trick is to become stabilized and have lowest energy. They are sitting on the top of potential energy high called transition state in chemistry. Here come the phenyl groups which share their electrons to stabilize the radical. Phenyl rings have a cloud of 6 pi electrons and they begin to disperse and stabilize the unpaired electron on the carbon be transporting the electron into the clouds especially on ortho and para positions. Since there are 3 phenyl rings, the dispersal of the unpaired electron is very large and thus the radical becomes stabilized. Also such molecules and radicals absorb light in the visible spectrum of light. Since it looks yellow in color, it means it absorbs the light in the lower part of spectrum leaving the yellow light for transmission.

When these solutions are exposed to oxygen which is famous for breaking into free radicals then the color begins to disappear and stable compounds are formed by reaction of 2 tri-phenyl methyl radical with one oxygen atom and is colorless.

We must appreciate the fact that in those times when not many of the analytical instruments were available, these chemists with their logic and classical compositional analysis were able to achieve so much insight. This is why the chemistry is called a fundamental science. Without it no field like geology, physics, biology, genetics and other modern science can progress. We must also give the due credit to Russian scientists whose works remained obscure in the era of communism when even the science discoveries were under the whip of communism.

For more details and diagrams please visit this page on wikipedia which is doing a great service to the world by imparting and dissemination of knowledge.