Food or edible material: processes – compositions – and products – Processes – Separating a starting material into plural different...
Patent
1995-04-21
1997-01-28
Paden, Carolyn
Food or edible material: processes, compositions, and products
Processes
Separating a starting material into plural different...
426492, 554 83, A23D 7005
Patent
active
055976026
DESCRIPTION:
BRIEF SUMMARY
BACKGROUND OF THE INVENTION
1. Field of the Invention
The invention relates to a process for recovering lecithin from oil- and lecithin-containing mixtures by extraction with an extractant comprising at least one hydrocarbon.
2. Description of the Background
The mixture of phosphatides referred to in the trade as lecithin is a group of phospholipids composed of the following structural members: glycerol, fatty acids, phosphoric acid, and amino alcohols and carbohydrates, respectively. They are found in practically any animal and Vegetable material. Ample amounts thereof are present in brain tissue, egg yolk, and oil seeds such as soybean oil and rape-seed oil.
Phosphatides of vegetable origin are generally highly unsaturated. In lecithin preparations of animal origin, there are found, besides glycerol esters, various sphingolipids and plasmalogens as phosphorus-containing compounds. The main constituents of soybean lecithin are phosphatidyl choline, phosphatidyl ethanolamine, phosphatidyl inositol, phosphatidyl serins, phosphatidyl acid, lysophospholipids, and phytoglycolipids.
In vegetable oils from oil seeds and cereal seeds such as soybeans, rape-seed, sunflower seed, corn, hemp and linseed, phosphatides are present in concentrations of from 0.2 to 2% by weight. Also used for the recovery of phosphatides are egg yolk, yeast lipids, and bacterial bio-mass. All of the above materials are suited as a source of phosphatide mixtures in the process of the invention, too. One specific example is the crude lecithin obtained in the refining of vegetable oils and fats.
At present, the major part of commercial lecithine is obtained in the processing of soybean oil and rape-seed oil. They contain lecithin in colloidal from. To the oil, water is added under stirring in accurately measured quantities, and the lecithin contained in the oil is hydrated at elevated temperature. The slimy mixture is separated in a separator and subsequently dried in a drying apparatus under a vacuum. Obtained in this manner is viscous crude lecithin. This crude lecithin recovered by extraction from soybeans or rape-seed in the course of a refining operation consists to about one third of oil and to two thirds of acetone-insoluble components, namely lecithin. For some applications, the oil content is disturbing, and further purification is required.
The term lecithin within the present description does not only mean natural lecithins but also chemically modified lecithins, the latter ones being of increasing interest.
It is state of the art to separate the oil from crude lecithin by extracting with acetone. The powdery product referred to as pure lecithin has a residual oil content of from 2 to 4% by weight. In the course of acetone extraction, there is withdrawn a fat/acetone solution as well as a suspension of phospholipids in acetone. The main part of the acetone is separated from the phospholipids by centrifuging and fed back into the solvent cycle. The partially dried product is then freed of residual solvent in at least two steps. A first drying step is conducted in a fluidized bed drier where the phospholipids are fluidized at about 50.degree. to 70.degree. C. by means of hot air. The main part of acetone is thus removed. To remove even the last traces of solvent, the product is subsequently dried in vacuum drying oven. In this step, thin layers of phospholipids are placed on racks and treated for several hours at elevated temperature (50.degree. to 70.degree. C.). A specific problem of the acetone extraction method are the streams of exhaust air from the drying steps, which may be vented to the environment only after proper purification. Pure lecithin is used not only as an emulsifying food additive but also in undiluted form as a dietetic. Thus, its purity, e.g. freeness of solvent, must meet strict requirements; in the case of acetone with its low threshold value regarding odour, special attention must be given to the above aspect.
The lecithin obtained through acetone extraction must be dried at temperature below 70.degree. C.
REFERENCES:
patent: 4367178 (1983-01-01), Heigel
patent: 4560513 (1985-12-01), Coenen
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patent: 4828702 (1989-05-01), Coenen
patent: 5028449 (1991-07-01), Hatanaka
patent: 5405633 (1995-04-01), Heidlas
patent: 5466842 (1995-11-01), Heidlas
Czech Bernd
Peter Siegfried
Weidner Eckard
Zhang Zhenfeng
Paden Carolyn
Peter Siegfried
LandOfFree
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