References

Peggy Trowbridge Filippone, 2006. Cabbage Varieties
Available from: [Assessed on 3rd November 2009]

Peggy Trowbridge Filippone, 2006. Cabbage and Health
Available from: [Assessed on 3rd November 2009]

The hidden, 2009.
Available from: [Assessed on 3rd November 2009]

"Where does the color come from in purple cabbage?." 07 August 2000. HowStuffWorks.com.
Available from: [Assessed on 3rd November 2009]

Appreciation

Special thanks for Dr. Wey Lim Wong for supporting us throughout the assignment.

What we had learnt in this assignment??

From this assignment, we had learnt about extraction of purple colour from purple cabbage and utilize it as natural colourant in other food products.

Besides that, we also got to know that anthocyanin is affected by pH environment, which can make it as a pH indicator. In this case, vinegar is added to stabilize its purple colour and remove cabbage odour.

Purple Pao Preparation

1. Mix NAGO Pau flour with instant yeast.

2. Pour in warm water. Mix well for 3 minutes.

3. Knead the dough with hand. Add in NAGO shortening.

4. Add in the natural colourant extracted from purple cabbage and knead the dough for 15 minutes until smooth.

5. Cover dough with wet cloth.

6. Leave the dough rest for 60 minutes and prove until double size and shaping

7. Put the filling into pau and mix well and put in some vegetable oil.

8. Flatten the skin and wrap filling in the shape of pau. Leave it rest for 30 minutes.

9. Steam over high heat for 30 minutes until cooked. Serve when hot.



From the picture above, we can see that right has darker colour compared to the left one. The right is natural colorant, anthocyanin, while the left is artificial colourant. The darker colour in natural colourant might be caused by degradation while steaming the bun, which is undesirable. On the other hand, artificial colourant is more heat-stable and can withstand the temperature rise during steaming, hence, there is no colour changes in it.

Purple Agar-agar Preparation

1. Dissolve one packet of Bites Agar Agar Powder (Jelly powder) and 250gm of fine sugar together and mix well.


2. Pour the mixture into 1 litre of cool water. Stir and bring to boil over low heat until mixure is dissolved.

3. Pour in feel drops of the clarified colourant which extracted from purple cabbage just now into mould.

4. Put mould into the refrigerator for 1 hour and serve chilled.



From the picture above, we can see that 22 has darker colour compared to 31. 22 is natural colorant, anthocyanin, while 31 is artificial colourant. The darker colour in natural colourant might be caused by degradation while boiling, which is undesirable. On the other hand, artificial colourant is more heat-stable and can withstand the temperature rise during boiling, hence, there is no colour changes in it. However, we can boil the agar solution in shorter period to minimise degradation of natural colourant. So that, the colour will be more attractive.

How do We Extract the Colour??

1. First, rinse the purple cabbage with water.

2. Then, cut it into slices and put in the blender.


3. Blend the purple cabbage slices with a small volume of water for 30 seconds.


4. Filter the blended juice of purple cabbage with a filter, allowing the clarified colourant to be collected in a bowl while the retentate is remained at filter.


5. Then, it is boiled for about 10 seconds with vinegar (It is to remove cabbage's odour and stabilize the purple colour)


6. After that, remove a thin layer that is formed on the solution by filtering it again into a bowl.

7. It is then ready as a natural colourant. =D

Yucks!!! It Stinks!!! =(

One of the weaknesses of purple cabbage is its ODOUR, which is to many reminiscent of rotten eggs and ammonia.

What Causes its to odour?
Cabbage contains sulphur compounds that actually multiply during the cooking process. The longer it's cooked, the more sulphur particles are released into the air, resulting in that odour that is objectionable to some. In fact, the amount of sulphides released while boiling cabbage doubles in the fifth through seventh minute of cooking. When cooked, older, more mature cabbage and cabbage that has been in long-term storage will be more odiferous than cabbage fresh from the garden. A bit of vinegar added as cooking liquid will help reduce the smell. Some chefs recommend a crusty end of bread tied up in a double wrapping of cheesecloth added to cooking cabbage will help alleviate odour. (The hidden, 2009)



Additional tips
YOU HAVE TO GO NUTS!!! Walnuts to be specific. Add a whole unshelled walnut to the cabbage water. You will discover the odor is absent.

The Mighty Purple Cabbage

Purple cabbage is well known by people because of its attractive colour possessed. Most often it is pickled, raw shredded red cabbage also makes a striking addition to traditional green salads. (Peggy Trowbridge Filippone, 2006)



The purple color in red cabbage comes from a class of pigment molecules called anthocyanins. It turns out that anthocyanins are found in flower petals, leaves (it makes them turn red in the fall!) and some fruits such as blueberries. Anthocyanins are plant pigments known as flavenoids and produce red, pink, violet and magenta colors in the various plant parts. ("Where does the color come from in purple cabbage?.", 2000)

The anthocyanidin group controls the color of the pigment. The electrons of the ring structures interact with incoming light and absorb various frequencies. The molecule shown below appears purplish red because its electrons absorb the yellow, green and blue portions of the visible spectrum. ("Where does the color come from in purple cabbage?.", 2000)

One of the things that changes the color on anthocyanins is the level of acid or alkali (i.e., pH) around the molecule. Because the color of the anthocyanin is affected by the pH of the environment, these molecules can tell you the pH of any substance. If you make an extract of red cabbage juice, it will change color when mixed with solutions of various pH. The anthocyanin turns bright pink in acids, reddish-purple in neutral solutions and green in alkaline or basic solutions. ("Where does the color come from in purple cabbage?.", 2000)

The Molecule



Here is the generalized structure for a purplish red anthocyanin molecule. Chemically, anthocyanins are made of a sugar molecule attached to a nonsugar part called anthocyanidin. This anthocyanidin has three rings, two 6-carbon (i.e. benzene) rings linked to another ring containing five carbons and one oxygen. The various anthocyanins differ from one another with respect to (1) the number and type of chemical groups, either hydroxyl groups (OH) or methoxy (OCH3) groups attached to the rings of the anthocyanidin and (2) to the sugar that forms the glycoside linkage (i.e. the bond between the sugar and the anthocyanidin. ("Where does the color come from in purple cabbage?.", 2000)

Benefits of Purple Cabbage

Therapeutic value As inexpensive as cabbage is, it is one of the richest when it comes to protective vitamins. Raw cabbage cleans the waste from the stomach and upper bowels, which improves digestion and reduces constipation. Hailed as a cancer inhibitor, particularly colon cancer, cabbage also stimulates the immune system, kills harmful bacteria, soothes ulcers, and improves circulation. The outer leaves are a good source of vitamin E, making it good for the complexion. Also rich in vitamin C, raw cabbage juice can be mixed with a milder juice, such as celery or tomato. Cabbage is alkaline in reaction, high in cellulose or roughage, and has a very low calorie count. Besides containing many minerals, cabbage is rich in calcium and potassium, and contains chlorine, iodine, phosphorous, sodium, and sulphur. Raw cabbage offers a fair amount of vitamin A and vitamin B. Red cabbage has more calcium, but slightly less of the other minerals than white and green cabbage. Red and white cabbage contain nearly the same vitamins and minerals and are used the same therapeutically. All these benefits are yours at only 24 calories per 3.5 ounces. (Peggy Trowbridge Filippone, 2006)

Purple Idea

How does this idea struck us??

Well, it is arised by our little cousins that prefer colourful food compared to those plain and dull ones. However, taking in too much of coloured food (by artificial means) will have adverse effect towards our health. Therefore, we thought of extracting purple colour from purple cabbage (Brassica oleacea var. capitata). Then, it can act as a natural colourant for other food products. In this assignment, we will be doing purple agar and purple 'pao'.