Freshe red tomato， white potato， green kelp， colorful food can enhance peoples appetite greatly. While the color of food will undergo various magical changes during cooking and storing， just like performing conjuring tricks.

In the world of food that can change its color， there is a special vegetable which is chameleon in vegetables， it is purple cabbage. The color of clean purple cabbage will turn into fresh red when vinegar is added on it， while it will change blue when adding acid. The outsiders tend to think the change is caused by pesticide residue， however， it is a little trick that made by purple cabbage itself. There is a pigment named anthocyanin in purple cabbage， such pigment will become red in acidic condition， blue in alkaline condition， so purple cabbage can change its color in differet environment. Similiarly， when purple sweet potato is boiled with egg， the egg will become green because anthocyanin of purple sweet potato will become green under the influence of basic protein of egg.

Green Laba Garlic

Caused by Enzyme

Put the peeled garlic into a sealed container， then pour some vinegar， seal the mouth of that container in a place with low temperature， after a short while， white garlic will turn into tempting green. What make them change their color？ The reason is that garlic has large quantity of active substance containing sulphur which can generate garlic green pigment， and yellow pigment by catalyzing of allinase in cold condition， the mixing of the two pigments make garlic fresh green. Similarly， ， de-magging reaction of chlorophyll of the vegetables will happen after adding vinegar to vegetable， then generate phaeophytin， and then produce pyropheophorbide acid， and green vegetables turn olive green， even brown.

Shrimp And Crab Turn Red

In High Temerature

Actually， shrimp and crab becoming red is a misunderstanding， they themselves have a red heart inside. There is a astacin， belonging to carotenoid， which is originally red ， in the pigment area of exoskeleton of shrimp and crab， but it can combine with different protein and turn red， orange， yellow， green， bluish violet and others. It will turn its original orange red when protein is broken， protein denaturation， or separted from original astacin. In normal conditons， the shell of crab and shrimp alive is dark green， but when they are put into the pan， most pigments will be decomposed by high temperature， only astacin has the ability to resisting hottness， and can not be decomposed in hot atmoshphere， it shows fresh redness instead. So ， it is not strange for the crab and shrimp turn red when they are boiled.

Green Burdock boided by iron pan

No matter blue， purple or red， they are all accepted color in food， here， we are going to introduce another color which might ruin your appetite. Burdock is generally considered to have the effect of maintaining beatuy and keeping young， and boosting immunity， however， most people see their boiled burdock turn green or horrible greyish-green ， and outwell the soup， actually speaking， it is the pigment of the soup that caused such change. The burdock is rich in phenols pigment which can lead to complexation with iron ion， such is the origin of the uncomfortable green or greyish-green， this is the reason why cooking with iron pan for traditonal Chinese medicine and vegetable is not strongly recommended. Tannin compound in lotus root will become black when putting in iron pan. And taking iron pan to cook sweet mung bean soup will change the soup into redness from greeness， this is because the interaction of flavonoid in the mung bean with metal ion might lead to dark compound.

Colorful food can enrich life of human beings， and knowledge of science can decode the secrets of food， making our life more healthy.