Composition and methods for preparing hemicellulose-rich extract from spend coffee ground
Methods of preparing a hemicellulose-product and a holocellulose-product from a carbohydrate-rich material, including spend coffee grounds, are described. Hemicellulose-products and holocellulose-products produced according to these methods are also described.
1. A method of producing a hemicellulose product, the method comprising:
treating an aqueous slurry of spend coffee grounds with an alkaline hydrogen peroxide solution;
separating a solid fraction from a liquid fraction of the alkaline hydrogen peroxide treated slurry;
adjusting the pH of the liquid fraction to a pH between about 4.0-6.0 using a pH adjusting agent;
combining an alcohol solution with the pH adjusted liquid fraction so as to precipitate a hemicellulose product; and
drying the hemicellulose product.
2. The method of claim 1 , further comprising a step of defatting the aqueous slurry by adding an organic solvent to the aqueous slurry prior to the step of adding an alkaline hydrogen peroxide solution.
3. The method of claim 1 , further comprising a step of concentrating the liquid fraction.
4. The method of claim 3 , wherein the concentrating step is carried out using a vacuum rotavapor.
5. The method of claim 3 , wherein the concentrating step is carried out by membrane filtration.
6. The method of claim 3 , further comprising a step of purifying the dried hemicellulose product.
7. The method of claim 6 , wherein the step of purifying the dried hemicellulose product comprises steps of dissolving the dried hemicellulose product in an aqueous solution and purifying the dissolved hemicellulose product by membrane filtration.
8. The method of claim 6 , wherein the step of purifying the dried hemicellulose product comprises steps of dissolving the dried hemicellulose product in an aqueous solution and purifying the dissolved hemicellulose product by column chromatography.
9. The method of claim 3 , further comprising a defatting step by adding an organic solvent to the concentrated pH adjusted solution prior to the step of precipitating the hemicellulose product.
10. The method of claim 3 , further comprising:
dissolving the precipitated hemicellulose product in an aqueous solution;
adding an organic solvent to the hemicellulose aqueous solution so as to remove fat from the solution; and
drying the defatted hemicellulose product.
11. The method of claim 1 , further comprising a step of purifying the dried hemicellulose product.
12. The method of claim 11 , wherein the step of purifying the dried hemicellulose product comprises steps of dissolving the dried hemicellulose product in an aqueous solution and purifying the dissolved hemicellulose product by membrane filtration.
13. The method of claim 11 , wherein the step of purifying the dried hemicellulose product comprises steps of dissolving the dried hemicellulose product in an aqueous solution and purifying the dissolved hemicellulose product by column chromatography.
14. The method of claim 1 , wherein ethanol is the alcohol solution combined with the pH adjusted liquid fraction to precipitate the hemicellulose product.
15. The method of claim 1 , wherein the hemicellulose product has a molecular weight of about 2 kDa to about 200 kDa.
16. The method of claim 15 , wherein the hemicellulose product comprises galactose in an amount of about 62%-94%, arabinose in an amount of about 9%-14%, and mannose in an amount of about 3.3%-5.1%.
17. The method of claim 1 , further comprising, prior to combining the spend coffee grounds with the alkaline hydrogen peroxide solution, combining the spend coffee grounds with ethanol and water for a sufficient time to remove lipophilic and hydrophilic components from the spend coffee grounds.
18. The method of claim 1 , further comprising recovering water insoluble fibers from the solid fraction.
19. The method of claim 18 , wherein the water insoluble fibers are delignified and decolored.
20. The method of claim 1 , wherein the alkaline hydrogen peroxide solution is added in the treating step such that an amount of hydrogen peroxide added is 1-5% w/w based on a total weight of the aqueous slurry.
21. A method of producing a hemicellulose product, the method comprising:
treating an aqueous slurry of spend coffee grounds with an alkaline hydrogen peroxide solution;
separating a solid fraction from a liquid fraction of the alkaline hydrogen peroxide treated slurry;
concentrating the liquid fraction by membrane filtration;
adjusting the pH of the concentrated liquid fraction to a pH between about 4.0-6.0 using a pH adjusting agent;
precipitating a hemicellulose product by adding ethanol to the pH adjusted solution; and
drying the hemicellulose product.
22. The method of claim 21 , wherein the alkaline hydrogen peroxide solution is added in the treating step such that an amount of hydrogen peroxide added is 1-5% w/w based on a total weight of the aqueous slurry.