Food or edible material: processes – compositions – and products – Inhibiting chemical or physical change of food by contact... – Treating liquid material
Reexamination Certificate
2002-07-23
2004-12-21
Paden, Carolyn (Department: 1761)
Food or edible material: processes, compositions, and products
Inhibiting chemical or physical change of food by contact...
Treating liquid material
C426S417000, C426S422000, C426S478000, C426S490000, C554S175000, C554S177000, C554S206000, C134S040000, C210S348000, C210S650000, C210S651000
Reexamination Certificate
active
06833149
ABSTRACT:
FIELD OF THE INVENTION
The invention relates to a method for processing vegetable oil miscella, an apparatus for processing vegetable oil miscella, a method for conditioning a polymeric microfiltration membrane for selective removal of phospholipids from vegetable oil miscella, a membrane for selective removal of phospholipids from vegetable oil miscella, and a lecithin product.
BACKGROUND OF THE INVENTION
Edible vegetable oils are generally obtained by processing oil seeds. Crude vegetable oils can be obtained from vegetable seeds by solvent extraction. Hexane is the most commonly used extraction solvent. The crude vegetable oils generally contain neutral triglycerides and a host of natural contaminants including phosphotides, sulphurous compounds, free fatty acids, carbohydrates, peptides, oxidized lipids, traces of lower aldehydes and ketones, glycosides of sterols and terpenes, and diverse types of color bodies or dyestuffs. These contaminants are removed from the crude vegetable oils in the course of refining in order to render the vegetable oils palatable.
The recovery of soybean oil from soybeans is particularly desirable. A technique for recovering soybean oil includes several processing steps. The soybean is dehulled and crude soybean oil is extracted with hexane. The extractant (miscella), which includes hexane and crude soybean oil, is further processing to recover palatable soybean oil. The hexane is evaporated from the miscella and the resulting crude soybean oil is degummed. Degumming, as used in conventional processes, refers to the removal of phosphatides and other gums from the oil by adding water and/or acid thereto and centrifuging. The recovered oil can be further refined with water and alkaline (such as NaOH) and centrifuged to remove the fatty acids and gums. The oil resulting from the alkaline refining step can then be bleached to remove color bodies, hydrogenated to render the oils more stable, and deodorized. The techniques of degumming, alkaline refining, bleaching, hydrogenating, and deodorizing are well known in the art. It should be appreciated that each separation step, and particularly centrifuging, results in loss of oil. The recovered gum concentrate from the conventional degumming process can be dried, if desired, and bleached to produce a commercial soybean lecithin.
Lecithin is used as an emulsifying agent, a dispersing agent, wetting agent, a penetrating agent, and an anti-oxidant. In addition, lecithin is used in food products, paints, inks, petroleum products, soaps, cosmetics and lubricants. Commercial lecithin is a mixture of phosphatides. Typically, commercially available lecithin includes about 62 wt. % acetone insoluble phosphatides.
Numerous prior art references describe techniques for obtaining vegetable oils by application of membrane technology. For example, U.S. Pat. No. 4,093,540 to Sen Gupta describes refining crude glyceride oils by contacting a composition of glyceride oils and organic solvent under pressure with a semi-permeable ultrafiltration membrane to separate constituents of different molecular weight into retentate and permeate fractions, and contacting the composition or at least one of the fractions with a metal oxide or metalloid oxide adsorbent in a column containing the adsorbent. Additional references which describe the use of membrane technology for separating phospholipids from crude vegetable oils include: U.S. Pat. No. 4,414,157 to Iwama et al.; U.S. Pat. No. 4,533,501 to Sen Gupta; Raman et al., “Membrane Technology”, Oils & Fats International, Vol. 10, No. 6, 1994, pages. 28-40; Ziegelitz, “Lecithin Processing Possibilities”, Inform, Vol. 6, No. 11, November 1995, pages. 1224-1213; Ondrey et al., “The Skinny On Oils & Fats”, Chemical Engineering, October 1997, pages. 34-39; Pioch et al., “Towards An Efficient Membrane Based Vegetable Oils Refining”, Industrial Crops & Products, 7 (1998) pages 83-89; Koseoglu et al., “Membrane Applications & Research In The Edible Oil Industry: And Assessment, JAOCS, Vol. 67, No. 4 (April 1990), pages 239-249.
SUMMARY OF THE INVENTION
A method for processing vegetable oil miscella is provided by the present invention. The vegetable oil miscella can be processed into desirable products including vegetable oil and concentrated lecithin.
The method for processing vegetable oil miscella includes a step of feeding vegetable oil miscella to a separation membrane for recovery of a permeate stream and a retentate stream. The separation membrane is provided for removing phospholipids. The recovered permeate stream has a decreased concentration of phospholipids compared with the concentration of phospholipids provided in the miscella. In addition, the retentate stream has an increased concentration of phospholipids compared with the concentration of phospholipids provided in the miscella.
In the context of the present invention, the permeate stream is the stream which flows through the membrane, and the retentate stream is the stream which does not flow through the membrane. The vegetable oil miscella includes extraction solvent and crude vegetable oils containing phospholipids. The vegetable oil miscella can be characterized as raw miscella when it is obtained from refers to as extractant from an extraction process for the recovery of vegetable oils and has not been clarified for the removal of solids. The vegetable oil miscella can be characterized as clarified miscella when it has be treated for the removal of solids.
The separation membrane refers to the membrane which provides for the separation of phospholipids from vegetable oil. The separation membrane can be referred to as the phospholipids separation membrane. In general, the separation membrane can be provided by modifying a membrane having a pore size of between about 0.05&mgr; and about 3&mgr;, and more preferably between about 0.1&mgr; and about 2&mgr;. The modification refers to conditioning which involves treating the membrane with a solvent or solvent system that allows the membrane to be used for separating phospholipids from vegetable oil. The polymeric membrane which is to be conditioned is generally a membrane provided in an aqueous medium. In order to use the membrane with miscella, the membrane can be conditioned.
The vegetable oil miscella preferably contains between about 45 percent by weight and about 90 percent by weight extraction solvent, and more preferably between about 70 percent by weight and about 80 percent by weight extraction solvent. A preferred extraction solvent includes hexane. The permeate stream preferably includes less than 0.6 weight percent phospholipids, more preferably less than about 0.15 weight percent phospholipids, and even more preferably less than about 0.015 weight percent phospholipids.
The vegetable oil miscella which is obtained from an extraction operation generally contains a relatively high level of solids which, if not removed from the miscella, will relatively quickly clog the phospholipids separation membrane. Accordingly, it is desirable to provide a prefilter system for removing the solids in the miscella. The prefilter system can include one or more filters in series to provide reduction of the solids content in the miscella. The resulting miscella having a reduced solids content can be referred to as clarified miscella. In general, the filters used to remove solids from the miscella have an average pore size in the range of about 0.05&mgr; and about 100&mgr;. It is generally advantageous to provide a series of filters having decreasing pore size so that upstream filters remove the relatively large solids and the downstream filters remove the smaller solids. The filters which can be used in the prefilter system need not include conditioned membranes. The filters used in the prefilter system can include stainless steel filters. In addition, the filters can be dead end filters and/or feed and bleed filters. Furthermore, the prefilter system can be practiced batch or continuous. In addition, it will be appreciated that although the filters used for separating phospholi
Jirjis Bassam
Muralidhara Harapanahalli S.
Otten Dennis D.
Cargill Incorporated
Merchant & Gould P.C.
Paden Carolyn
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