Abstract
Juice were extracted from fresh leaves of 70 species of plants growing in Korea by mincing and pressing the resulting pulp through a cotton cloth. Leaf protein concentrates could be prepared from many species of land and water plants that are at present economically unimportant. The choice of plants is of considerable important. Total-N, protein-N and pH determinations were made on the extracts, and total-N remaining in the fibre were calculated. Leaf protein concentrates were precipitated from the extracts at $75{\sim}80^{\circ}C$, and analysed total-N as protein-N of products. The present paper deals with the calculated yields of leaf protein concentrates from various plants, relations between yield of leaf protein concentrates and total-N of leaves, or pH of extracts, and the amino acid compositions of leaf protein concentrates. Results are summarized as follows. 1. Spinach and radish were the best sources of easily extractable, but good results were also obtained with indian mustard, kail, chenopod, red bean, cucumber, squash, houndberry, white flowered gourd, potato, Humulus japonicus, arrowroot and soybean as a good resources for the production of leaf protein concentrates. 2. In general, the greater the protein content of leaves the greater the yield of leaf protein concentrates. However, there are some plants difficult to make a adequate protein extraction by a simple mechanical process. 3. It was to be expected that leaf protein concentrates would be more extractable with the higher pH of extracts. There were a poor yield of the leaf protein concentrate in the pH values lower than 5.50 of the first extracts. 4. Protein content of the leaf protein concentrate shows marked differences, depending on species and season. It ranged between 29 to 80% of protein contents. However, the majority of plants yielded products containing more than 50% of protein. Products containing more than 75% of protein were obtained from two species of radish and indian mustard. Cabbage and Digitaria sanguinalis cilialis (summer) made products containing 29 to 32% of protein. 5. The amino acid composition of leaf protein concentrates was not greatly altered by species of plants. On an amino acid compositional basis, the leaf protein concentrate has a favorable balance of essential and non-essential amino acids, the only exception being methionine, which was usually low in all cases.
70종(種)의 각종 식물(植物)잎을 대상으로 하여 종류(種類)에 따른 LPC의 수율(收率), 원료(原料)잎의 총질소량(總窒素量), 1 차(次) 추출액(抽出液)의 pH 와 LPC의 수율(收率)과의 관계(關係), LPC의 아미노산(酸) 조성(組成) 등을 조사(調査)하여 다음과 같은 결과(結果)를 얻었다. 1. 시금치, 열무는 LPC의 순수율(純收率)이 $10{\sim}13%$(총수율(總收率) $16{\sim}23%$), 한삼덩굴, 오이, 참외, 박, 명아주, 콩, 양호박, 감자, 개미취, 호박, 치마아욱, 갓, 망초, 양배추 등은 순수율(純收率)이 $3.6{\sim}8.5%$ (총수율(總收率) $6{\sim}14%$)로서 비교적(比較的) 좋은 LPC의 자원식물(資源植物)이 될 수 있다. 2 LPC의 수율(收率)은 원료(原料)잎의 총질소량(總窒素量)이 많을 수록 커지나 그 변이(變異)는 크고, 종류(種類)에 따라서는 질소함유량(窒素含有量)이 많은데도 단순(單純)한 기계적(機械的)인 추출(抽出)로서는 단백질(蛋白質)의 추출(抽出)이 잘 이루어지지 않는 것이 적지 않다. 3. 1차(次) 추출액(抽出液)의 pH가 5.50 이하(以下)의 종류(種類)는 대체적(大體的)으로 LPC의 수율(收率)이 낮고, pH 가 높은 종류(種類)일 수록 LPC의 수율(收率)도 커지는 경향(頃向)이 있다. 4. LPC의 단백질(蛋白質) 함량(含量)은 종류(種類)에 따라서 차이(差異)가 많으나 대부분(大部分)의 것이 50% 이하(以下)의 단백질(蛋白質) 함량(含量)을 갖는다. 왜무, 갓, 케일, 명아주, 팥, 참외, 양호박, 까마중, 박 등의 LPC는 $71{\sim}76%$의 좋은 단백질(蛋白質) 함량(含量)을 갖는다. 5. LPC의 종류별(種類別) 아미노산(酸) 조성(組成)의 차이(差異)는 없고, 콩의 LPC에서 phenylalanin이, 참외에서 serine이 다소 많은 것을 제외(除外)하고는 대체적(大體的)으로 비슷한 아미노산(酸)의 함량(含量)을 보이며, 다른 식품(食品)의 아미노산(酸) 조성(組成) 및 조성비(組成比)와 비교(比較)하여 LPC는 매우 훌륭한 단백질원(蛋白質源)이 될 수 있다.