Abstract: Leafy vegetables are an important source of protein and other nutrients. Vegetable protein is characterized by different and variable amino acid composition. This study determined the protein content and amino acid composition of the leaves of garden rocket (Eruca sativa Mill.) as affected by different nitrogen and potassium nutrition regimes. On average, the rocket leaves accumulated 11.7% dry matter, including 16.6% protein. Increased nitrogen rates resulted in a significant decrease in protein content as opposed to increased potassium rates. In the majority of cases, the increasing rates of nitrogen and potassium used in the nutrition of rocket plants significantly modified the amino acid composition of protein, which contained all primary amino acids, both nonessential and essential. In the group of nonessential amino acids, glutamic acid and aspartic acid were predominant. The proportions of all the amino acids determined were substantially lower than in the FAO/WHO reference guidelines. The greatest variation was found in the case of threonine and lysine, while the smallest was for sulfur amino acids. It was shown that the rocket leaves were characterized by a high content of protein with a beneficial amino acid composition, and rocket should be taken into consideration as a diet component. Modifications in the plant nutrition system can be used to increase the amount of rocket protein and to obtain its specific chemical profile.

Abstract: Leafy vegetables are an important source of protein and other nutrients. Vegetable protein is characterized by different and variable amino acid composition. This study determined the protein content and amino acid composition of the leaves of garden rocket (Eruca sativa Mill.) as affected by different nitrogen and potassium nutrition regimes. On average, the rocket leaves accumulated 11.7% dry matter, including 16.6% protein. Increased nitrogen rates resulted in a significant decrease in protein content as opposed to increased potassium rates. In the majority of cases, the increasing rates of nitrogen and potassium used in the nutrition of rocket plants significantly modified the amino acid composition of protein, which contained all primary amino acids, both nonessential and essential. In the group of nonessential amino acids, glutamic acid and aspartic acid were predominant. The proportions of all the amino acids determined were substantially lower than in the FAO/WHO reference guidelines. The greatest variation was found in the case of threonine and lysine, while the smallest was for sulfur amino acids. It was shown that the rocket leaves were characterized by a high content of protein with a beneficial amino acid composition, and rocket should be taken into consideration as a diet component. Modifications in the plant nutrition system can be used to increase the amount of rocket protein and to obtain its specific chemical profile.