Persian clover (trifolium resupinatum) was cultivated on a soil which was analyzed completely by mechanical and chemical methods. The changes in a atmospheric temperature and relative humidity during the growing season were recorded. The crop was harvested after different intervals and the effects of climatic conditions, length of day (photosynthesis period) and age on the crop were studied.
The plant growth, dry mater and nitrogen content varied considerably during the season due to the changes in atmospheric temperature, relative humidity, length of day and age. Harvesting of the crop after an interval of 20 â€“ 100 days showed variations in yield/hectare of fresh and dry weights and nitrogen content in a season. Thirty day old 1st cut and the successive regrowths gave the maximum yield or fresh and dry weights, i.e. 86.59 and 11.23 ton/hectare/season. The total nitrogen contents were however, more in case of 20 day old 1st and regrowths, i.e. 423 kg/hectare/ season.
The amount of extractable nitrogen (EN) in the juice and extractable protein nitrogen (EN) precipitated from the juice by heating at 80 + 20c or with TCA, was also affected considerably by the changes in climatic conditions, age and maturity of the crop. The percent extraction of these fractions varied negligibly up to the age of 60 days, till the end of March. The per hectare-yield of EN and PN however increased. Twenty day old 5th regrowth, 30 day old 3rd regrowth, 40 day old 2nd regrowth and 60 day old 1st regrowth, harvested in the month of march , gave comparatively more yield/hectare of en and pn than that of their respective 1st cuts and regrowths. The percent as well as per hectare yield of these fractions continuously decreased in 20 â€“ 10 day old regrowths taken after March, when the flowering and seed development was in progress. The maximum yield of easily extractable protein in a season was 900 kg/hectare, which was obtained from the 30 day, old 1st cut and subsequent eight regrowths.
The percentage of non-protein us nitrogen (NPN) in the juice increased an increase in the age of plant and such changes were more rapid during reproductive stages. The over all variations in NPN during the season were from 14.12 to 94.2% when the age of 1st cut ad regowths increased from 20-100 days. This increase in NPN was attributed to the breakdown of proteins by the proteolytic enzymes present in the plant.
The percentage or FR increased and its nitrogen content decreased with an increase in the age of cuts and regrowths. The per hectare yield however, depended on the yield of crop. Thirty day old 1st cut and regrowths gave maximum yield of FR (6.412 ton/hectare/season) which contained about 200 kg. nitrogen . Twenty day old 1st cut and regrowths although contained the same amount of nitrogen but the yield of FR was FR obtained from 20 and 30 day old cuts and regrowths contained sufficient proteins (17.5 and 0.7%) and can be recommended for animal feeding.
The volume of waste liquor and its nitrogen content depended entirely on the volume of the juice extracted from the crop and its NPN content. The yield of waste liquor from 20 to 40 old harvests (1st cuts and regrowths) was from 64542 to 67338 litre/hectare/season. This volume was much more than that of 60-100 day old 1st cuts and regrowths. This by-product contained considerable amount of nutrients and proved to be a suitable substrate for propagation of candida utilis. The yield of food yeast on the dry weight basis was 5.3 kg/ litre of waste liquor.
The maximum yield of protein, from a unit area of the land, including the protein obtained from the waste liquor by propagation of food yeast was estimated to be 1078 kg/hectare/season.
The leaf protein cake (LPG) prepared from the crop was dehydrated and defatted for increasing the stability of the shelf-life of the product. Several preparations were made from LPC by freeze drying, oven drying, roller drying and solvent extraction. The effects of different processing conditions on the nutritive value of proteins were studied by in vitro methods and microbiological estimation of total and available amino acids. The dehydration of LPC by freeze drying and solvent extraction did not effect the nutritive value of the proteins. Drying of LPC over hot air at 70-100 c in an oven or by passing over steam heated rollers reduced the extractability of lipids. Moreover the in vitro digestibility with papa in, net protein utilization and amino acid availability also decreased considerably .This decrease in the nutritive value of heated leaf proteins can be attributed to the oxidation of unsaturated lipids and formation of complexes with the proteins.
The extraction of *eated proteins with chloroform: methanol (2 : 1) mixture of acetone increased their digestibility with papain from 48.02 to 66.58% and net protein utilization from 47.0 to 67.55% . This increase in nutritive value showed that solvent treatments eliminated the oxidation and copolymerized products formed during moist heating of proteins. The solvent extraction also resulted in a greater release of bound amino acids with papa in. None of the bound lysine was released from the heated products with solvent extraction and the amount available to leuconostoc mesenteries after the enzymic hydrolysis ranged from 5.81 to 5.0 g/ 16 g n.
The leaf protein cake, products dried over hot air at 80 + 2oc and the freeze dried sample after extraction with acetone showed better papin digestion ability , NPU and amino acid availability than the other preparations . These products can be stored at room temperature and recommended for supplementing the protein deficient diets of human beings.