Hou Xilin, a professor at the School of Horticulture of south china agriculture University, and other experts selected these eight varieties of vegetables in the experiment, namely Jingyan Shepherd, Nanjing Shepherd, Nanjing Mosaic Shepherd and Jinan Shepherd, and two green vegetables, namely Jingguan Rape, Mayslow Rape, 06-8 and Beijing New. All the sampled varieties were planted in the open air by experts, and repeated three times.
By comparison, it was found that the proportion of essential amino acids in shepherd's purse was the highest, the content of Chinese cabbage was the lowest, and green vegetables were in the middle. It is worth mentioning that, except methionine and cysteine, the proportion of other essential amino acids in shepherd's purse is much higher than that proposed by the World Health Organization and the Food and Agriculture Organization of the United Nations in protein Zhong 1973.
In the experiment, experts also measured and compared the soluble sugar content, soluble protein content and vitamin C content of water shield, Chinese cabbage and Chinese cabbage, and found that the soluble sugar content of Chinese cabbage was significantly higher than that of water shield and Chinese cabbage, while the soluble sugar content of water shield was the lowest, and the soluble sugar content of Chinese cabbage was 2-4 times that of water shield. Similarly, the content of soluble protein and vitamin C in Chinese cabbage is the highest, but these two components in shepherd's purse are higher than that in Chinese cabbage, and the soluble protein content of some shepherd's purse varieties is higher than that in Chinese cabbage. As for the content of vitamin C, the content of vitamin C in Chinese cabbage is almost three times that of Chinese cabbage, while shepherd's purse is half or almost close to that of Chinese cabbage. Hou Xilin said that the data show that the nutritional value of water shield is between green vegetables and Chinese cabbage, and green vegetables have the highest nutritional value.