Method for enzymatic synthesis of sucrose esters

Details Method for enzymatic synthesis of sucrose esters Method for enzymatic synthesis of sucrose esters

2000-01-10

2002-03-12

Prats, Francisco (Department: 1651)

Chemistry: molecular biology and microbiology

Micro-organism, tissue cell culture or enzyme using process...

Preparing oxygen-containing organic compound

C435S100000, C435S198000, C435S219000, C536S115000, C536S119000

Reexamination Certificate

active

06355455

ABSTRACT:

FIELD OF THE INVENTION
The invention concerns the field of processes for synthesising substances and relates to a method for enzymatic synthesis of sucrose esters.
BACKGROUND OF THE INVENTION
Sucrose esters are surfactants resulting from the combination of a sugar with a fatty acid by an ester bond. By varying the nature of the sugar and the length of the fatty chain it is possible to obtain a group of molecules which have a very wide range of hydrophilic-lipophilic balances and thus of functional properties. One can thus produce foaming, non-foaming, liquefying, solubilising and emulsifying surfactants.
These products are natural ingredients relating to the cleaning, cosmetic, pharmaceutical and agro-nutrition sectors.
The sucrose esters which are now commercially available are generally produced by chemical synthesis.
They are generally complex mixtures of various compounds, as a result of the non-specific nature of the chemical condensation reactions between the sugars and fatty acids. The high temperatures and pressures necessary for these reactions thus also lead to parasitic reactions and colouring of the products.
Sucrose esters may also be obtained by condensation reactions catalysed by enzymes, for example lipases. These enzymatic reactions have the advantage of being more specific than chemical synthesis and taking place at normal temperatures and pressures.
SEINO et al. have proposed (J. Am Oil Chem. Soc. 61, 1761-1765, 1984) esterifying sugars (sucrose, glucose, fructose, sorbitol) with fatty acids (stearic, oleic, linoleic) in the presence of an enzyme in an aqueous medium. But this technology does not enable significant quantities of sucrose esters to be obtained.
Specifications WO 90/09451 and WO 94/01575 further describe methods of obtaining sucrose esters in the total absence of water and without using any solvent. However this technology necessitates preliminary alkylation of the sugars to allow them to be solubilised in the fatty phase. This technology for the production of esters from alkyl sugars and fatty acids also has the disadvantage of producing a preparation containing an excess of non-converted fat and thus of necessitating complex purifying operations if high purity levels are required for the resultant sucrose esters. Moreover the high viscosity of the reaction materials used makes the operations complicated to carry out.
ZAKS A. and KLIBANOV A. M. (Proc. Natl. Acad. Sci. USA, 82, 3192-3196, 1985) have firstly described enzymatic synthesis of sucrose esters of fatty acids in an organic solvent. However the pyridine used is a toxic solvent which is prohibited for industrial applications.
In addition, the use of organic solvents of the tertiary alcohol type to carry out enzymatic synthesis of sucrose esters has also already been proposed.
Thus specification FR-A-2 646 439 and KHALED et al. (Biotech. Letters, 13, 167-172, 1991) describe the synthesis of fructose, sorbose, sorbitol and mannitol oleate and fructose palmitate using an immobilised lipase and 2-methyl-2-butanol as solvent. However these synthesising processes still have a poor performance: final sucrose ester concentrations of the order of 20 g/l, sugar conversion yields of no more than 50% and specific productivity of below 0.01 g of sucrose esters produced per hour per gram of catalyst. Moreover the excessive amounts of fatty acids used necessitate complex operations to fractionate the mixtures of sucrose esters and fats obtained.
DUCRET et al (Biotechnol. Bioeng. 48, 214-221, 1995) describe the synthesis of fructose and glucose oleate in 2-methyl-2-butanol by an immobilised lipase, with a partial vacuum being maintained above the reaction medium. This technology gives higher degrees of conversion, 93% for fructose oleate and 70% for glucose oleate. However the final concentrations of sucrose esters are still low (23 g/l for fructose oleate, 17 g/l for glucose oleate) and the specific productivity is less than 0.1 g of sucrose ester per hour per gram of catalyst. Nor does the technology enable esters of saccharose or lactose to by synthesised.
Finally, WOUDENBERG et al. (Bioeng. 49, 328-333, 1996) describe enzymatic esterification of disaccharides such as sucrose with ethyl butanoate and ethyl dodecanoate, using an immobilised lipase and 2-methyl-2-butanol as solvent. But the final concentrations and specific productivity (0.04 g/h.g) obtained are very low.
SUMMARY OF THE INVENTION
The main aim of the invention is to alleviate all the foresaid disadvantages and to propose a method for enzymatic synthesis of sucrose esters which, compared to the known methods mentioned above, enables a clearly improved performance to be obtained in terms of final concentrations of sucrose esters, conversion yields (for both the sugars and fats originally present) and specific productivity, while reducing the complex, tedious post-synthesis purifying operations.
To this end the invention concerns a method for the enzymatic synthesis of sucrose esters, characterised in that it consists in introducing, in an adapted reactor and so as to form a reaction medium, predetermined amounts of an organic solvent, a sugar or a sugar derivative, a compound donor of acyl groups and an enzymatic catalyst, the amount of at least one constituent of the reaction mixture being deficient, in controlled addition during the reaction of additional amounts of the deficient constituent(s), and finally, in purifying the resulting sucrose esters at least by separating the enzymatic particles (for example by decanting, filtering or centrifuging) and the solvent (for example by evaporation, distilling or membrane filtration).
The method according to the invention more specifically consists, in the course of the synthesising reaction, of continuously or intermittently adding to the reaction medium defined additional quantities of sugar or sugar derivative in solid form or in the form of a liquid solution, of solvent, of enzymatic catalyst in soluble or immobilised form and/or of acyl-donor compound alone or solubilised in the solvent.
Thus the main difference between the method of the invention and the known methods previously described is the manner in which the enzymatic reaction is conducted.
In known methods for enzymatic synthesis of sucrose esters the full quantities of constituents of the reaction medium are placed in the reactor at the beginning of the reaction.
Now according to the invention only a defined initial quantity of one or more constituents of the reaction medium is initially placed in the reaction vessel, and additional quantities of the constituent or constituents partially introduced at the beginning are added in the course of the synthesising reaction.
By checking the quantity of reagents added it is possible to control how the composition of the reaction medium develops in the course of time, and thereby to direct the enzymatic reaction to maximum production of monoesters and/or diesters, while limiting parasitic reactions.
In accordance with the invention the reaction is conducted in such a way that the inhibition of the enzymatic reaction which is observed in the presence of strong concentrations of sugars or acyl donors is initially limited.
It has thus been found that, to obtain a high final concentration of sucrose esters, it is preferable not to place the full quantities of the necessary reagents in the reactor to begin with, but rather to introduce them gradually in a controlled manner in the course of the reaction, and to avoid reaching concentration levels which would inhibit the enzyme reaction.
The reaction is conducted in such a way that the molar ratio of [sugar(s) or sugar derivative(s)/acyl(s) donor] is controlled for its whole duration.
The molar ratio may advantageously be from 0.01 to 10.00, preferably from 0.02 to 2.00, according to the constituents forming the sugar(s) or sugar derivative(s)/acyl(s) donor pair in question.
By fixing molar ratio values within the above ranges in the reaction medium it is possible to obtain either higher reaction speeds or maximum proportions of suc

Affiliated with

Also associated with

Rating

Method for enzymatic synthesis of sucrose esters does not yet have a rating. At this time, there are no reviews or comments for this patent.

If you have personal experience with Method for enzymatic synthesis of sucrose esters, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Method for enzymatic synthesis of sucrose esters will most certainly appreciate the feedback.

Rate now

Comments { 0 }

Profile ID: LFUS-PAI-O-2872210