Method for the Extraction of Oily Components from Coffee Beans and/or of Residual Materials of Coffee Production

Abstract

A method for moist extraction of oil-containing components from coffee beans and/or residues from coffee production, wherein the coffee beans and/or residues from coffee production with a residual moisture content of 10 to 95 percent by mass, measured with reference to the total mass of the coffee beans and/or residues from coffee production are extracted with a mixture of extraction agents consisting of at least one each of a polar and a nonpolar solvent.

Claims

1. Method for moist extraction of oil-containing components from coffee beans and/or residues from coffee production, wherein the coffee beans and/or residues from coffee production with a residual moisture content of 10 to 95 percent by mass, measured with reference to the total mass of the coffee beans and/or residues from coffee production, are extracted using a mixture of extraction agents consisting of at least one polar and one nonpolar solvent, and wherein the mixture of extraction agents contains the at least one nonpolar solvent in a percentage of 45 to 95 vol %, measured with reference to the total volume of the extraction agent.

2. Method according to claim 1, characterised in that gasoline, kerosene, toluene, an alkane having a chain length of 5 to 25 carbon atoms or a mixture thereof is used as the at least one nonpolar solvent.

3. Method according to claim 1, characterised in that an alcohol having a chain length from one to 10 carbon atoms is used as the at least one polar solvent.

4. Method according to claim 1, characterised in that the mixture of extraction agents contains the at least one polar solvent in a proportion of 5 to 55 vol %, measured with reference to the total volume of the extraction agent.

5. Method according to claim 1, characterised in that the mixture of extraction agents contains further polar and/or nonpolar solvents with a proportion by volume totaling 0.5 to 40 vol %, measured with reference to the total volume of the mixture of extraction agents.

6. Method according to claim 1, characterised in that the mixture of extraction agents is used at a temperature above ambient temperature but below the boiling point of the solvent with the lowest boiling point or the boiling point of the azeotrope with the lowest boiling point in the mixture of extraction agents.

7. Method according to claim 1, characterised in that coffee beans and/or residues from coffee production having an average grain size from 0.001 to 10 mm are used.

8. Method according to claim 1, characterised in that coffee beans and/or residues from coffee production having a content of oil-containing components from 5 to 60 percent by mass, measured with reference to the total dry matter of the coffee beans and/or residues from coffee production are used.

9. Method according to claim 1, characterised in that the oil-containing components are separated from the mixture of extraction agents by distillation after the extraction.

Description

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0062] The invention will now be explained in greater details with reference to the embodiments listed, but without limitation thereto.

Example 1—Moist Extraction with Industrial Coffee Grounds

[0063] For extraction using binary extraction solutions, fresh, moist Robusta coffee grounds from industrial instant coffee production with a water content of 68% and an oil content of 17.3% in the dry mass were used.

[0064] Portions of 27 and 28 g moist coffee grounds were each deposited separately in a filter having a pore size of 100 μm and collected in a beaker. The beakers were each filled with 100 ml extraction solution of compositions of various mixtures of n-hexane and 2-propanol in volumetric proportions between 45:55 and 85:15, and one beaker with pure hexane. Both the mixtures and the pure hexane were warmed to 60° C. The samples were allowed to rest in the extraction solutions for 10 min and then removed. The samples were then allowed to drip for a further minute. Then, the recovered miscellae were distilled, and the recovered oil was analysed gravimetrically. The coffee grounds were also dried to determine the mass of the respective sample and thus determine the maximum recoverable oil quantity. This theoretical oil quantity and the actually recovered oil quantity were subsequently compared. With moist extraction it was possible to recover between 50 and 95 percent by mass of the oil, wherein the yield with an n-hexane component of 70 and 85 vol % was between 90 and 97%. Outside of this optimal range, extraction efficiency fell sharply, and with pure n-hexane (100 vol %) the yield was 0%.

Example 2—Moist Extraction with Decanter Slurry From Instant Coffee manufacture

[0065] For moist extraction, fresh, moist decanter slurry from the manufacture of instant coffee with a water content of 75.4% and an oil content of 14.6% in the dry mass was used. The decanter slurry originated from the industrial instant coffee production. Portions between 42 and 43 g of moist decanter slurry were each placed in separate beakers and dispersed in 48 to 49 g extraction solution at 60° C. The extraction solutions were various mixtures of n-hexane and 2-propanol with volumetric proportions between 45:55 and 70:30. The material remained in the extraction solutions for 20 min. The miscellae were then filtered and distilled, and the quantity of recovered oil was determined gravimetrically. With moist extraction it was possible to recover between 50 and 99 percent by mass of the oil from decanter slurry without drying.

Example 3—Moist Extraction with Industrial Arabica Coffee Grounds

[0066] For this experiment, deep frozen industrial Arabica coffee grounds having a residual moisture of 60.4% and an oil content of 31.2% in the dry mass were analysed. The coffee grounds were stored in the refrigerator 7° C. for 24 to thaw them. For the experiments, a 65:35 (n-hexane:2-propanol) extraction solution was used. 50 g coffee ground was deposited in a filter and placed in a beaker. The sample was infused with with 100 ml of a mixture of extraction agents, which was warmed to 60° C., poured out and allowed to rest for 15 min. Then, the miscella was drawn off and washed three times, each time with 30 ml warm extraction agent mixture. In this way, it was possible to recover 89% of the oil, whereas an experiment with warm n-hexane yielded less than 1%.