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Why to Turn Green after Cooking Seaweeds

Views:1574 Author:WZH Publish Date:2017-11-13

In recent days, some customers consult Wan Zi Hui worker: why do the seaweeds become green from black after cooking?

Many people will have a common question when seeing this message? Is there any chemical reagent added into seaweeds or whether is seaweed poisonous?

First of all, we should now what state is fresh seaweed. Then, we will understand why to turn green after cooking seaweeds?

The seaweeds for soup in supermarkets and online stores are almost porphyra haitanensis which are produced in Fujian, Jiangsu and Zhjiang. The seaweeds are in the sea and they will be harvested, cleaned, dried then can be sold. The common porphyra haitanensis are discoidal and rectangle.

How to identify fresh seaweeds

No matter what grade of seaweeds is, the identification of seaweed grades can be through three steps: the first step is observing, the second is smelling, and the third is touching.

1.Observe whether the color is black and good luster or not. High quality seaweeds are gloss black. And if seaweeds become purple, they are not fresh and can not bought.

2.Smell the fragrance is fresh or not. If the fishy smell is strong and rotten, it means that seaweeds have been spoiled.

3.Touch the seaweeds are fluffy and flexible or not. Because the seaweeds will get wet easily when they are exposed to the air, we can't open the package at will. But we can touch the seaweeds without opening package. If the seaweeds become soft, it means that they get wet and that the taste and nutrition will be lost.    

Why to turn green after cooking seaweeds

Mr.Shijun, as Doctor of Institute of Botany, Chinese Academy of Sciences, gives an answer:

Reason 1: 

There is a special chromoprotein called phycoerythrin in porphyra haitanensis. And phycoerythrin can be dissolved in the water and this chromoprotein is not stable and it can be dissolved once getting heated. So seaweeds turn into green after cooking.  


Reason 2:

In addition to phycoerythrin, there is chlorophyll, carotene, xanthophyll and so on and the chlorophyll content is the highest, which replace phycoerythrin. So seaweeds become green.

Those long stored seaweeds will become green because of de-gradative  phycoerythrin and thy can be ate without worries.  

If you are interested in porphyra haitanensis wholesale, sushi nori or any questions, please call: 0513-85327612