The proteins from leaves

Abstract

The nature and main characteristics of the leaf proteins are reviewed, stressing the even aminoacid composition of the different crops suitable for protein extraction. A satisfactory pattern of essential aminoacids is also shown to be a general characteristic. The principles of the wet fractionation of green vegetables are then reviewed; details are given on the squeezing stage and the criteria for the recovery of the proteins from the expressed juice are reported. The different physico-chemical status of such proteins requires different processes for their recovery as a whole or in fractionated bulk. Therefore, three different leaf protein concentrates (LPCs) can be obtained: cytoplasmatic (white), chloroplastic (green) and whole LPC, the last being a combination of the other two. Processes for LPC production as animal feed have already been established at the industrial level; procedures giving LPC for human consumption are at the laboratory or pilot scale. In this paper, attention has been paid to the criteria for the preparation of edible LPC, which are essentially based on both the decoloration of green whole LPC and the fractionated recovery of the cytoplasmatic and chloroplastic proteins present in the juice. In this second process, the white fraction is reserved for humans and the green LPC for animals. Technological aspects of the production of the above-mentioned LPCs are described and some nutritional and functional properties of the final products are briefly illustrated.