Patent Application: US-27881307-A

Abstract:
from palm oil , valuable compounds like the tocochromanols , carotenoids , phytosterols and other can be derived in the new process . fractions derived from crude palm oil , already enriched to some extent in tocochromanols , carotenoids , phytosterols , and others , are treated by supercritical fluid technology in a unique combination of counter current separation with selective adsorption and desorption using supercritical fluids .

Description:
with supercritical carbon dioxide as solvent , in a first separation sequence ( fig2 , columns c 1 and c 2 ), from the tocochromanols or the carotenoids are removed the compounds more soluble in supercritical carbon dioxide than the target compounds at the top of a counter currently operated separation column , and the less solube soluble compounds at the bottom . this process leads to concentrations for the tocochromanols of about 70 wt .-%, and for the carotenoids of about 30 wt .-%. the details of this separation are given below . in a second sequence , directly following the countercurrent process , the mixtures are processed by selective adsorption and desorption steps ( fig2 , adsorbers a 1 , a 2 , a 3 ). adsorption takes place from the mass flow taken from the countercurrent separation comprising a supercritical or near - critical fluid and the target compounds , and is directly deposited on the adsorbent . in this way , the handling of the highly viscous solution or solid solution is made possible . subsequently , desorption is carried out from the fixed bed loaded with the feed mixture . desorption may be carried out with the same supercritical or near critical fluid , or a different one , or in a sequence of two or more of such solvents . desorption is also carried out at different conditions compared to the adsorption , i . e . different values of pressure , temperature , flow rate of gas . supercritical or near critical solvents may comprise mixtures of supercritical or near critical fluids , preferably of carbon dioxide and propane . it was found that the separation by adsorption and desorption can be improved by not filling the whole adsorbent with the feed mixture , but only part of it . during desorption a sequence of adsorption and desorption steps take place , which increase the separation efficiency , and thus the concentrations of the separated fractions . the ratio of the first adsorbed section to the free section of the fixed bed of adsorbent is variable , usually from 0 . 5 to 0 . 1 . fig2 . flow sheet of the process for concentrating tocochromanols and carotenoids by sfe technology . the new process for the production of highly enriched tocochromanol - fractions , containing mostly tocotrienols from palm oil derived mixtures combines a continuous countercurrent multistage separation using a supercritical fluid , preferably carbon dioxide , to remove the lighter volatile ( i . e . the compounds more soluble in supercritical compound , resp . carbon dioxide ) over the top of the column . the bottoms of the column are an enriched fraction in tocotrienols with a relatively high content in sterols and other somewhat polar compounds . this bottom fraction is passed over a suitable adsorbent . silicagel was found to be an applicable adsorbent . the adsorbed mixture is desorbed by a supercritical fluid , preferably carbon dioxide in two desorption steps . the first is carried out at a pressure of about 140 bar and removes more volatile or more in supercritical carbon dioxide soluble compounds . in the second desorption step , carried out at about 250 bar , highly enriched tocochromanol fractions , containing mostly tocotrienols , are extracted . the extracted fractions can be split further by collecting them in different vessels . depending on the cut of the fractions , the concentration of tocotrienols is in the range of 85 to nearly 100 % with a yield of about 50 % of the feed mixture . the adsorbent is regenerated with liquid solvents like ethanol etc . and reused for the adsorption step . the process starts with a pre - enriched fraction , which may be obtained by several methods , one may comprise transesterification of the glycerides with methanol and removing the obtained fatty acid esters by short - path - distillation or by extraction with supercritical fluids , like carbon dioxide . for example , the starting material for the first extraction step was a palm oil derivatives that among other substances contained 56 wt .-% tocochromanols ( with γ - tocotrienol , α - tocotrienol , and α - tocopherol being the major components ), 16 wt .-% squalene , 5 wt -% phytosterols ( with β - sitosterol and campesterol being the most prominent species ), and 11 wt .-% mono - and diglycerides . this material was fed into a continuously operated extraction column , employing supercritical carbon dioxide as solvent . the column was packed with a structured sulzer ex packing and has an inner diameter of 17 . 5 mm and a total height of 7 m , of which 6 m are packed . employing pressures of 20 - 30 mpa and temperatures of 323 to 358 k , it was possible to produce a sterol - and tocochromanol - free top product , only extracting specifically fame , squalene , and monoglycerides , hence obtaining a bottom product enriched to about 70 % tocochromanols with phytosterols and other most probably more polar compounds comprising the rest . a longer column would have completely depleted the bottom phase from the higher - volatile components . with chemical engineering methods the necessary height for complete separation of fame , squalene , and monoglycerides from tocochromanols , sterols , and other low - volatile components was calculated . the results are that a complete separation of these components is possible with 13 theoretical separation stages , corresponding to a height of the column of about 15 m , a solvent - to - feed ratio of 80 to 140 , with a reflux ratio of 6 to 12 , at a temperature of 323 k , and a pressure of 20 - 25 mpa . theoretically , the further enrichment of tocotrienols should be possible by employing another countercurrent separation using a supercritical fluid . experimental investigations revealed that the solubility of the tocotrienol - enriched bottom product in supercritical carbon dioxide is too low to be considered as a solvent for a separation process . therefore , modifiers were mixed with the basic supercritical fluid , carbon dioxide , in order to increase the solubility . the following solvent compositions were investigated : co 2 + propane with a propane content of 29 , 55 , and 83 %, as well as co 2 + liquid organic solvent , namely ethanol , iso - propanol , 1 - butanol , and ethyl acetate , each in a concentration of 5 and 10 wt .-%, respectively . the measurements were conducted in a pressure range of 5 - 30 mpa and at temperatures of 323 , 343 , and 358 k , respectively , in case of experiments with propane and at a fixed pressure of 20 mpa and at temperatures of 323 and 343 k in case of the liquid modifiers . at all conditions investigated the concentration of the low volatile compounds was enriched in the gaseous phase , but the selectivity with respect to tocotrienols was reduced to such an extent that sterols were dissolved in the gas - phase , hence making it impossible to enrich the tocotrienol concentration further . surprisingly it was found that the separation factors remained high , even increased , if the bottom material was mixed with special silica gels and then desorbed or extracted from this adsorbent with supercritical carbon dioxide . the bottom product from the first enriching step was mixed with certain amounts of adsorbent ( silica gel ) in a ration of 4 to 10 . the mixture was introduced into a column as fixed bed . then , applying a supercritical fluid ( carbon dioxide ) at a pressure of about 14 at a temperature of about 333 k , remaining high volatile components such as fatty acid esters and squalene were desorbed . in a second desorption ( extraction )- step , at about the same temperature , but a higher pressure of about 25 mpa tocotrienols were desorbed with high concentration . with a ratio of adsorbent to feed of 10 , a solvent ratio of supercritical carbon dioxide of about 300 [ kgco 2 / kg feed and hour ], a fraction of 27 % of the feed was obtained during 1 h with a concentration of 75 % tocotrienols , after that fraction , another fraction of 25 % of the feed with a 100 % concentration of tocotrienols could be recovered in another hour . experiments with a mixture of carbon dioxide and propane showed that the solubility could be enhanced while the selectivity was maintained . therefore , the solvent ratio can be lower than with pure co 2 . a carotenoid concentrate ( 1 to 10 wt .-%) is fed into a continuously operated extraction device , constructed as a five - stage high pressure mixer - settler . in three separation sequences with this apparatus , employing pressures of 20 - 30 mpa and temperatures of 323 to 358 k , it was possible to produce a product , containing up to 30 wt .-% of carotenoids . this product is passed over the adsorbent , a special silica gel , preferably zeofree 5170 , whereby the mixture of carotenoids , sterols and other substances , and the fatty acid esters are adsorbed . the mixing ratio is in the range of 4 to 10 . subsequently , the loaded adsorbent is brought into contact first with suspercritical carbon dioxide , and then with near critical propane at conditions of the state , e . g . 5 mpa and 323 k , preferably in the range of 2 to 7 mpa and 313 to 343 k . with carbon dioxide , mainly non - carotenoids are desorbed and eluted , and with near critical propane , the carotenoids are desorbed . the solvent ratio of propane to feed is in the range of 20 to 100 preferably about 30 . concentration of the eluted carotenoids were enhanced , if during the adsorption step only a fraction of the adsorbent was loaded with the feed . a continuous operated multi - stage supercritical extraction was conducted with pure carbon dioxide as solvent and a feed mixture containing 50 wt .-% tocochromanols ( with γ - tocotrienol , α - tocotrienol , and α - tocopherol being the major components ), 16 wt .-% squalene , 3 wt -% phytosterols ( with β - sitosterol and campesterol being the most prominent species ), and 11 wt .-% mono - and diglycerides . the employed column had an effective height of 6 m and was packed with a structured sulzer ex packing . operating conditions were as follows : 20 mpa , 323 k , solvent - to - feed ratio = 19 . 8 , reflux ratio = 7 . 3 . these conditions resulted in a top phase product consisting of 2 wt .-% fame , 58 wt .-% squalene and it was completely depleted from tocochromanols and phytosterols . the bottom product consisted of 8 wt .-% squalene , 58 wt .-% tocochromanols , 4 wt .-% phytosterols , and it was completely fame - free . a continuous operated multi - stage supercritical extraction was conducted with pure carbon dioxide as solvent and a feed mixture containing 50 wt .-% tocochromanols ( with γ - tocotrienol , α - tocotrienol , and α - tocopherol being the major components ), 16 wt .-% squalene , 3 wt -% phytosterols ( with β - sitosterol and campesterol being the most prominent species ), and 11 wt .-% mono - and diglycerides . the employed column had an effective height of 6 m and was packed with a structured sulzer ex packing . operating conditions were as follows : 20 mpa , 343 k , solvent - to - feed ratio = 40 . 3 , reflux ratio = 1 . 3 . these conditions resulted in a top phase product consisting of 2 wt .-% fame , 60 wt .-% squalene , 2 wt .-% tocochromanols , and 1 wt .-% sterols . the bottom product consisted of 7 wt .-% squalene , 54 wt .-% tocochromanols , 4 wt .-% phytosterols , and it was completely fame - free . 1 g of the bottom product obtained from example 1 was used as feed material and mixed with 10 g of silica gel , zeofree 5170 . the mixture is introduced into an empty vessel and supercritical co 2 was used to desorb fame and squalene at 13 mpa and 333 k for 120 minutes . the pressure was increased to 25 mpa and after 60 minutes , a fraction ( 0 . 27 g ), which contains 80 wt .-% of tocochormanols , was collected . the pressure was held constant for another 60 minutes , another fraction ( 0 . 24 g ) was collected . this fraction contains approximately 100 % tocochromanols . 2 . 4 g of the bottom product obtained from example 1 was used as feed material and mixed with 10 g of silica gel , zeofree 5170 . the mixture is introduced into an empty vessel and supercritical co 2 was used to desorb fame and squalene at 13 mpa and 333 k for 60 minutes . the pressure was increased to 19 mpa and after another 120 minutes , a fraction ( 1 . 59 g ) was collected . it contains 80 wt .-% of tocochromanols . the carotenoids concentrate containing approximately 10 wt % of carotenoids was passed over the adsorbent in an high pressure pipe with an internal volume of 50 ml . silica gel with a minimum surface area of 165 m 2 / g was used as the adsorbent with a ratio of 4 : 1 ( 12 g : 3 g ) to the amount of feed . extraction was then carried out first with supercritical carbon dioxide at 150 bar and 60 ° c ., and then with supercritical carbon dioxide at 250 bar and 60 ° c . in third step , near critical propane was used at 7 mpa , 60 ° c . the fractions are collected . the last fraction consisted of about 60 % carotenoids . 1 . y . m . choo : palm oil carotenoids . the united nations university press , food and nutrition bulletin , 15 ( 1994 ). 2 . c . lenfant , f . c . thyrion : extraction of carotenoids from palm oil , i . physical and chemical properties of β - 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