Food or edible material: processes – compositions – and products – Processes – Preparing or treating triglyceridic fat or oil – or processes...
Reexamination Certificate
2001-03-28
2004-03-16
Paden, Carolyn (Department: 1761)
Food or edible material: processes, compositions, and products
Processes
Preparing or treating triglyceridic fat or oil, or processes...
C426S478000, C426S330600, C554S017000, C554S023000
Reexamination Certificate
active
06706299
ABSTRACT:
FIELD OF INVENTION
The present invention relates to a process for the preparation of rice bran oil low in phosphorous content. More specifically, the present invention relates to a process for the pretreatment of rice bran oil for its further processing by physical or chemical refining. The pretreatment aims at the removal of all phosphorus-containing compounds including the phosphorus-containing glycolipids.
BACKGROUND OF THE INVENTION
Owing to the presence of the phosphoglycolipids, crude rice bran oil cannot be degummed by known chemical methods to the levels required for physical refining.
Rice bran oil is an important vegetable oil. India produces about 5,00,000 tons of rice bran oil annually. Rice bran oil is considered to be a superior edible oil owing to its balanced fatty acid composition and the presence of nutritionally beneficial constituents such as &ggr;-oryzanol, squalene, tocopherols, tocotrienols etc. (deDecker, E. A. M. and Korver, O.,
Nutr. Rev.,
1996, 54 (11), S120). In China and Japan rice bran oil is one of the most favoured edible oils, popularly known as “heart oil”. Unfortunately, though India is the largest producer of this commodity, only about 10% of the rice bran oil produced go for direct human consumption. High free fatty acid content, high wax content, high non-saponifiable matter content and dark colour all add to the problems associated with rice bran oil refining.
For production of edible oils of highest quality, the refining process generally comprises the steps of degumming, deacidification, bleaching and deodorization. In recent times considerable efforts have been made to make the degumming process in particular, more efficient and cost effective. The desired goal in this connection is to degum the oil to such an extent that it can subsequently be deacidified by means of vacuum distillation (physical refining). This distillative deacidification has great advantages compared to the conventional process of alkali neutralization in that no waste is produced and that the refining loss is considerably reduced. However, a prerequisite for this process of physical refining is a very low content of phosphatides, i.e., a phosphorus content of less than 15 ppm in the oil, preferably less than 10 ppm. Phosphorus content of less than 5 ppm is ideal. For oils containing high FFA (such as rice bran oil), physical refining is the preferred mode of processing. Practical experience with physical refining shows that it leads to desirable results only when a very good quality of starting material is used. For successful operation of physical refining, efficient pretreatment steps are, therefore, of utmost importance. There are no efficient pretreatment processes which would make all fats and oils amenable to physical refining irrespective of their initial quality (Forster, A. and Harper, A. J.,
J. Am. Oil Chem. Soc.,
69, 1983, 265). Incomplete removal of undesirable components from the oil in the pretreatment steps can be compensated in some cases by increased bleaching earth usage in the bleaching step (Ohlson, K,
J. Am. Oil Chem. Soc.,
69, 1992, 195).
The major emphasis, thus, has to be placed on preliminary processing of crude oil prior to steam refining. This should be aimed at removal of any component of the oil that may darken the color or undergo other adverse alterations during the high temperature operation and thus, deteriorate the quality of the oil. It is truly said that technology of physical refining is more about how to remove gums and other impurities in upstream processing, i.e, in degumming and bleaching (Norris, F. A., in
Bailey's Industrial Oil and Fat Products,
Vol. 3, T. H. Applewhite (ed.), John Wiley & Sons, NY, 1985). The development of physical refining technique, therefore, is more dependent on the development of the pretreatment methods.
Degumming is the first step whereby the crude oil is subjected to treatment before the operation of removal of free fatty acid is undertaken. Degumming primarily removes phospholipids and other mucilages from oil and quality of the degummed oil is generally judged by its phosphorus and trace metal contents. If not removed effectively in the initial stage, these impurities may eventually interfere with the subsequent refining steps. Phospholipids present in oils are broadly classified as hydratable and non-hydratable types While hydratables are removed from oil by a simple water degumming step, non-hydratables need some special treatment. Phosphoric acid and citric acid are commonly used in practice to remove non-hydratable phosphatides. However, as they are not soluble in oil, these acids must be thoroughly mixed to achieve the desired results.
Stringent requirements of raw material quality for oils meant for physical refining saw the development of number new degumming processes and newer adsorbents in the pretreatment steps. References may be made to the development of various types of degumming processes. Alcon process was developed to attain the trading specifications of soybean oil by water degumming (Kock, M., in:
Proceedings of Second ASA Symposium on Soybean Processing,
American Soybean Association, 1981). Later it was extended to steam refining of oils (Penk, G., Paper presented at the ISF-AOCS World Congress, Tokyo, 1988). Dry degumming method was slightly modified by replacing a part of the bleaching earth by a synthetic silica hydrogel, Trisyl (Welsh, W. A. and Parent, Y. O., Eur. Pat. EP 0185 182, 1986) to get an oil fit for physical refining. A variety of modifications of the acid degumming was also suggested (Mag, T. K. and Reid, M. P., U.S. Pat. No. 4,240,972, 1980; Carlson, K. F., in:
Bailey's Industrial Oil and Fat products,
Vol. 4., fifth edition, Y. H. Hui (ed.), John Wiley & Sons Inc., New York, 1996). Superdegumming was developed by Unilever (Segers, J. C.,
Fette Seifen Anstrichm.,
84, 1982, 543) and later modified by others (Kaji, T., Eur. Pat. EP 0269, 277, 1988; Van de Sande, R. I. K M and Segers, J. C., Eur. Pat. EP 0348004, 1989). Another group of scientists had developed total degumming process, popularly known as TOP degumming (Dijkstra, A. J. and Van Opstal, U.S. Pat. No. 4,698,185, 1987). It was claimed that this process was useful to reduce phosphorus and iron level to attain the quality of the oil which might go for physical refining (Dijkstra, A. J., in:
Proceedings of World Conference on Oilseed Technology and Utilization,
Budapest, Hungary, T. H. Applewhite (ed.), AOCS, Champaign, Ill., 1993, 138).
Unfortunately, as applied to crude rice bran oil, none of these methods produce oil of low phosphorus content. Even enzymatic methods using phospholipase A
2
were not satisfactory. However, a process making use of lipase G (an enzyme not normally used for degumming) was found to give satisfactory results (T. N. B. Kaimal et. al, Indian Pat. 184,701 (2000). Our continued research traced the difficulties in degumming of rice bran oil to the presence of phosphorus-containing glycolipids in the oil (unpublished results). These phosphoglycolipids are not removed by the known degumming methods and we have been successful in removing these compounds from the oil by extraction of the crude oil with alcoholic solvents such as isopropanol or ethanol (Indian patent applied for). While the method has given satisfactory results, the use of organic solvents and the resultant loss of oil in the organic phase during the process could be considered drawbacks. This led us further to search for non-solvent methods to achieve the results.
OBJECTS OF THE INVENTION
The main object of the invention is to provide a process for the removal of phosphoglycolipids by reaction of the acidic phosphate groups of those lipids with a mild organic base such as ethanolamines.
Another object of the invention is to provide an simple, economical and fast process for obtaining phosphorus free rice bran oil.
SUMMARY OF THE INVENTION
Accordingly, the present invention provides a process for the preparation of rice bran oil low in phosphorous content (<10 ppm) said by treatment
Ongole Rajamma
Potula Satya Bhaskar
Thengumpillil Narayana Balagopala Kaimal
Council of Scientific and Industrial Research
Ladas & Parry
Paden Carolyn
LandOfFree
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