Composition of, and process for preparing, silica xerogel for beer stabilization
View Patent ↗A silica xerogel, a process for making it, and a process for using it to reduce chill haze in beer includes incorporation in the xerogel of one or more alkali metals, optionally in combination with one or more alkaline earth metals. The pH of the xerogel is between 8.0 and 10.5, preferably between 8.5 and 10.0.
1. A composition comprising a silica xerogel comprising between 0.2 and 1.0 mmol/g of a metal component per gram of the xerogel, wherein said metal component comprises at least one alkali metal in an amount between 0.2 mmol/g and 1.0 mmol/g, the xerogel having a pH between 8.0 and 10.5.
2. The composition of claim 1 , wherein the xerogel comprises between 0.3 and 0.8 mmol/g of the metal component per gram of the xerogel.
3. The composition of claim 1 , wherein the xerogel comprises between 0.4 and 0.7 mmol/g of the metal component per gram of the xerogel.
4. The composition of claim 1 , wherein the at least one alkali metal is sodium.
5. The composition of claim 1 , wherein the at least one alkali metal is potassium.
6. The composition of claim 1 , wherein the pH of the xerogel is between 8.5 and 10.0.
7. The composition of claim 1 , wherein the xerogel is an acid-set xerogel.
8. The composition of claim 1 , wherein the xerogel is an alkaline-set xerogel.
9. The composition of claim 1 , wherein the xerogel is a calcined xerogel.
10. The composition of claim 1 , wherein the xerogel is a hydrothermally treated xerogel.
11. The composition of claim 1 , wherein the metal component further comprises at least one alkaline earth metal.
12. The composition of claim 11 , wherein the xerogel comprises less than 0.1 mmol/g in total of said at least one alkaline earth metal.
13. The composition of claim 12 , wherein the xerogel comprises between 0.3 and 0.8 mmol/g of the metal component per gram of the xerogel.
14. The composition of claim 12 , wherein the xerogel comprises between 0.4 and 0.7 mmol/g of the metal component per gram of the xerogel.
15. The composition of claim 12 , wherein said at least one alkali metal is sodium.
16. The composition of claim 12 , wherein said at least one alkali metal is potassium.
17. The composition of claim 12 , having a pH between 8.5 and 10.0.
18. The composition of claim 12 , wherein the xerogel is an acid-set xerogel.
19. The composition of claim 12 , wherein the xerogel is an alkaline-set xerogel.
20. The composition of claim 12 , wherein the xerogel is a calcined xerogel.
21. The composition of claim 12 , wherein the xerogel is a hydrothermally treated xerogel.
22. The composition of claim 11 , wherein:
the xerogel is a hydrothermally treated xerogel comprising less than 0.1 mmol/g in total of said at least one alkaline earth metal;
the xerogel comprises between 0.4 and 0.7 mmol/g of the metal component per gram of the xerogel;
said at least one alkali metal is sodium; and
the pH is between 8.5 and 10.0.
23. A method of making a silica xerogel comprising the steps of:
a) contacting an aqueous alkali metal silicate with an amount of an aqueous mineral acid sufficient to neutralize between 70% and 95% of the alkali metal in the alkali metal silicate, thereby forming a hydrogel;
b) contacting the hydrogel with an aqueous solution of an alkaline earth metal salt to incorporate at least a portion of the alkaline earth metal into the hydrogel;
c) aging the hydrogel;
d) washing the hydrogel with water; and
e) drying the hydrogel to form a xerogel;
wherein the silica xerogel comprises between 0.2 and 1.0 mmol/g of a metal component per gram of the xerogel comprising at least 0.2 mmol/g but less than 1.0 mmol/g of the alkali metal per gram of the xerogel and correspondingly no more than 0.8 mmol/g but more than 0 mmol/g of the alkaline earth metal per gram of the xerogel, the xerogel having a pH between 8.0 and 10.5.
24. The method of claim 23 , wherein a molar ratio of the alkali metal to the alkaline earth metal in the metal component is between about 5:95 and about 95:5.
25. The method of claim 23 , wherein a molar ratio of the alkali metal to the alkaline earth metal in the metal component is between about 30:70 and about 70:30.
26. The method of claim 23 , further comprising a step of:
f) calcining the xerogel.