Green vegetation fractionation technology - A review

Availability of abundant sunlight and excessive photosynthesis in our country has resulted in the production of different kinds of huge lush green vegetations which form bulk mass of raw material and incomparable wealth. These vegetations could be utilized by fractionation technology to yield useful products of much economic value. However, all the vegetations can not be exploited through this technology. Only those vegetations which are succulent, have good protein content and less fibre, have high extractability, are free of mucilage and antinutritional constituents or have their low contents are suitable for fractionation. Green vegetation fractionation technology, a bioengineering process comprises of two steps. The first step involves the pressing of green vegetation/green foliage to obtain juice which in turn is coagulated by heat/steam to yield three products namely fibrous residue (FR), leaf protein concentrate (LPC) and deproteinised juice (DPJ). Fodder crops such as berseem (Trifolium alexandrinum L.) and lucerne (M edicago sativa L.); by-product leaves of crops e.g. potato (Solanum tuberosum L.), beet root (Beta vulgaris), cauliflower (Brassica oleracea) and turnip (Brassica rapa); water weeds such as water hyacinth (Eichhornia crassipes); weeds of cultivated crops such as bathua (Chenopodium species); tree leaves e.g. mulberry (Morus alba L.) and gliricidia (Gliricidia maculata L.) and wild plant species such as chakvad (Cassia tora L.) appeared to be the promising green vegetations suitable for fractionation. The fractionation of green vegetation can be conducted at the laboratory scale by using electrically operated green vegetation mincer which can process 6 to 8 kg green vegetation per hour. For fractionation at large scale, Screw Press Machine could be used which can process the vegetation at the rate of 100 kg per hour. Fibrous residue, the first product of fractionation containing on an average 11% protein, 5% ether extract, 9% ash and 75% carbohydrate on dry weight basis has variety of uses depending on the source. It forms excellent cattle or pig feed in the fresh or dried forms or as silage and could be used as substrate for the production of mushrooms, as soil amendment or as raw material for the production of ethanol/methanol. LPC, the second product of fractionation contains on an average 50% protein, 10% ether extract, 6% ash and 34% carbohydrate on dry weight basis. Besides these major nutrients, it is also rich in pigments like chlorophylls and xanthophylls and in p-carotene, the precursor of vitamin A and tocopherol. It could be used as poultry feed, as milk replacement for calves, as human food and as a source of p-carotene in human nutrition. DPJ, the third product of fractionation containing on an average 5 to 6% dry matter and having 18% protein, 1% ether extract, 15% ash and 40% soluble carbohydrate in the dry matter could be utilized as cattle feed by mixing with FR, as a fertilizer with irrigation water for the improvement of soil fertility, as medium for tissue culture and as a substrate for the growth of yeast or other microorganisms yielding various products of pharmaceutical importance or other uses. Green vegetation fractionation technology appears to be very much relevant in the present era of our concerted efforts for utilizing efficiently the abundantly available green biomass such as fodder crops, by-product foliage of crops, water weeds and other weeds of cultivated crops, tree leaves and wild plant species or other plant species which may be identified in future as suitable for fractionation. The technology appears to have great potential in raising the income of such farms on which fodder crop production is integrated with dairy and poultry production. This review also includes priorities in green vegetation research which may serve as guidelines for future researchers in the area.