Method of preparing a liquid, containing proteins for subsequent separation, by using one or more protein-complexing agents
The invention relates to a method of preparing a liquid, which contains proteins (esp. haze sensitive proteins), for subsequent separation of at least haze-forming material, when predetermined filter aids are used. The method includes the addition of protein-complexing agent to the liquid, which agent is capable of forming a complex with at least some sensitive proteins of the liquid, to result in a limitation of the residual haze of the liquid, obtained after the separation (e.g. filtration), step.
1. A method of filtering a liquid comprising haze-sensitive proteins, the method comprising:
(a) providing a synthetic filter aid on a filter support;
(b) providing a liquid to be filtered, the liquid comprising haze sensitive proteins;
(c) adding protein-complexing agents to said liquid to be filtered;
(d) allowing the protein-complexing agents and the haze sensitive proteins to react so as to obtain a complex in said liquid; and
(e) filtering said liquid comprising said complex over the synthetic filter aid on said filter support so as to obtain a filtered liquid having a 25° haze less than 0.7 EBC.
2. The method according to claim 1 , wherein the filtering step is a “surface” filtration process.
3. The method according to claim 1 , wherein the synthetic filter aid comprises synthetic polymers selected from the group consisting of polyvinylpolypyrrolidone (PVPP), polyamide, polyvinylchloride, fluorinated products, polypropylene, polystyrene, polyethylene, polybutene, polymethylpentene, ethylene copolymers, binary copolymers and terpolymers with acrylics, olefinic thermoplastic elastomers and mixtures, polypolymers or co-extrusions thereof.
4. The method according to claim 3 , wherein the mixture of synthetic polymers used as filter aid is reusable after regeneration.
5. The method according to claim 2 , wherein the surface filtration process is an electrostatic attraction between the complex and at least one synthetic polymer of the filter aid.
6. The method according to claim 5 , wherein the at least one synthetic polymer has a positive electrostatic charge.
7. The method according to claim 6 , wherein the at least one synthetic polymer having a positive electrostatic charge is PVPP.
8. The method according to claim 7 , wherein the PVPP is mixed with other polymers in a predetermined proportion, in function of the polyphenol content in the liquid, resulting in a mixed filter aid, in order to obtain colloidal stability of the filtered liquid.
9. The method according to claim 1 , wherein the protein-complexing agent is selected from one or more members of the group consisting of: tannin, carrageenan, isinglass, pectine, xanthan gum, colloidal silica, chitosan, alginate, and cationic starch.
10. The method according to claim 9 , wherein the tannin protein complexing agent is gallotannin.
11. The method according to claim 10 , wherein gallotannin is added to the liquid to be filtered at a dosage rate between 0.1 g/hl and maximum 2 g/hl, as a function of the haze sensitive protein content of the liquid to be filtered.
12. The method according to claim 3 , wherein colloidal silica is added to the liquid to be filtered at a dosage rate between 10 g/hl and maximum 25 g/hl, as a function of haze sensitive protein content in the liquid to be filtered.
13. The method according to claim 1 , wherein the liquid to be filtered is a fruit or a cereal based beverage with a pH between 4 and 6.
14. The method according to claim 13 , wherein the beverage is a malt based beverage.
15. The method according to claim 14 , wherein the beverage is a fermented malt based beverage with a pH between 3 and 5.
16. The method according to claim 15 , wherein the fermented malt based beverage is a beer.