Dual mitigation of GE during the physical refining of edible oils and fats
A vegetable oil physical refining process able to mitigate the occurrence of glycidyl esters (GE) including at least a deodorization step followed by a stripping step, wherein, the deodorization step includes contacting said vegetable oil with steam at a pressure above 5 mbara, during at least 10 minutes at a temperature of at least 230° C., and wherein the stripping step includes stripping the oil resulting from the deodorization step at a pressure below 5 mbara and at a temperature not exceeding 280° C. The process does not compromise the heat bleaching and the full removal of unwanted colours, taste and smell from the physically refined edible oil.
1. A process for the physical refining of vegetable oil including:
a) a deodorization step carried out at a pressure above 5 mbara, at a temperature of at least 230° C. and during at least 10 minutes,
b) a steam-stripping step of the oil resulting from the deodorization carried out at a pressure below 5 mbara, and at a temperature not exceeding 280° C.,
wherein the free fatty acids (FFA) concentration of the oil resulting from the deodorization step contains at least 0.5% of FFA, and further contains no more than 5 ppm of glycidyl esters (GE).
2. The process according to claim 1 wherein said deodorization step is carried out at a pressure:
above 10 mbara;
above 20 mbara; or
above 50 mbara.
3. The process according to claim 1 wherein said deodorization step is carried out at a temperature of:
at least 245° C.; or
at least 260° C.
4. The process according to claim 1 wherein said steam-stripping step is carried out at a pressure:
below 3 mbara; or
below 2 mbara.
5. The process according to claim 1 wherein said oil resulting from the deodorization step contains:
at least 1% of FFA; or
at least 2% of FFA.
6. The process according to claim 1 wherein said oil resulting from the deodorization step contains:
no more than 3 ppm of GE;
no more than 2 ppm of GE;
no more than 1 ppm of GE; or
no more than 0.5 ppm of GE.
7. The process according to claim 1 wherein the oil arising from said stripping step is:
cooled at a temperature not exceeding 230° C. in less than 5 minutes;
cooled at a temperature not exceeding 230° C. in less than 5 minutes and further deodorized in a second deodorization step by contacting said cooled oil with steam at a temperature not exceeding 230° C. and at pressure below 5 mbara for a duration of at least 10 minutes; or
cooled at temperature not exceeding 230° C. in less than 5 minute and further deodorized in a second deodorization step by contacting said cooled oil with steam at a temperature not exceeding 230° C. and at pressure below 5 mbara for a duration of at least 10 minutes and the steam exiting the second deodorization step is at least partially recycled in the deodorization step a) and/or the steam-stripping step b).
8. The process according to claim 1 wherein the vegetable oil intended to be physically refined is:
washed and/or degummed and/or chemically bleached;
bleached by contacting it with bleaching earth and said contacting is realised at a low pressure; or
bleached by contacting it with bleaching earth and said contacting is realised at a low pressure and the deodorization step a) is realised essentially at the same low pressure.
9. The process according to claim 1 wherein FFA is added to the vegetable oil about to be deodorized.
10. The process according to claim 1 wherein said stripping step is carried out by contacting the oil with the stripping steam:
in a metallic packed column;
in a falling film; or
in a shallow tray deodorizer.
11. The process according to claim 1 wherein the steam exiting the steam-stripping step b) and containing fatty matters stripped from the oil:
is cooled and at least a part of said fatty matter is condensed to yield a liquid fatty phase that is at least partially added in the vegetable oil intended to be deodorized;
is cooled and at least part of said fatty matter is condensed to yield a liquid fatty phase, said liquid fatty phase being heated at a temperature of at least 200° C.; or
is cooled and at least part of said fatty matter is condensed to yield a liquid fatty phase, said liquid fatty phase being heated at a temperature of at least 200° C., and at least partially added in the vegetable oil intended to be deodorized.
12. The process according to claim 1 wherein said vegetable oil is a tropical oil, wherein said tropical oil is palm oil, palm kernel oil, coconut oil, or karite oil.
13. The process according to claim 1 wherein said vegetable oil has already been physically refined or modified by processes, wherein said processes are solvent and/or dry fractionation, interesterification or hydrogenation.
14. The process according to claim 1 wherein said vegetable oil contains 1 to 10% FFA.
15. The process according to claim 1 wherein said vegetable oil is supplemented with FFA.