Pigment extraction system and method

Abstract

A method for extracting a color-enhancing pigment includes separating citrus fruit into in-line pulp and juice and then separating the juice into clarified juice and retentate. The retentate or the in-line pulp is then homogenized to form a slurry, and the pigment is recovered from the slurry. The extraction method of the present invention is accomplished without the use of enzymes or harsh organic solvents, but rather is aqueous-based. The system includes an extractor and a finisher to separate citrus fruit into in-line pulp and juice. An ultrafiltration unit is used to separate the juice into clarified juice and retentate. Homogenization is accomplished with applied pressure, and pigment recovery, by washing and centrifugation.

What is claimed is:  
     
         1 . An aqueous method for extracting a color-enhancing pigment from citrus fruit comprising the steps of: 
 separating citrus fruit into in-line pulp and juice;    separating the juice into clarified juice and retentate;    homogenizing at least one of the retentate and the in-line pulp to form a slurry; and    recovering the pigment from the slurry.    
     
     
         2 . The method recited in  claim 1 , wherein the citrus fruit separating step comprises the step of sending the citrus fruit through an extractor and a finisher to produce the in-line pulp and juice.  
     
     
         3 . The method recited in  claim 1 , wherein the juice separating step comprises the step of filtering the juice.  
     
     
         4 . The method recited in  claim 3 , wherein the filtering step comprises employing ultrafiltration on the juice.  
     
     
         5 . The method recited in  claim 1 , further comprising the step of debittering the in-line pulp prior to the homogenizing step.  
     
     
         6 . The method recited in  claim 5 , wherein the debittering step comprises rinsing the in-line pulp with water having a temperature sufficiently high to remove bitter compounds from the in-line pulp and sufficiently low to prevent damage to the pigment.  
     
     
         7 . The method recited in  claim 6 , wherein the bitter compounds comprise naringin and limonin.  
     
     
         8 . The method recited in  claim 6 , wherein the temperature comprises approximately 45° C.  
     
     
         9 . The method recited in  claim 1 , wherein the recovering step comprises washing the slurry with an aqueous solution and centrifuging the washed slurry, the pigment remaining in a supernatant of the centrifuging step.  
     
     
         10 . The method recited in  claim 9 , wherein the washing and centrifuging steps comprise repeated cycles of washing and centrifuging the slurry.  
     
     
         11 . The method recited in  claim 9 , further comprising the step of filtering the supernatant.  
     
     
         12 . The method recited in  claim 1 , further comprising the step of subjecting the homogenized retentate to centrifugation, a supernatant therefrom containing the pigment.  
     
     
         13 . The method recited in  claim 12 , further comprising the step of filtering the supernatant.  
     
     
         14 . The method recited in  claim 12 , further comprising the steps of washing a pellet from the centrifuging step with an aqueous solution to extract additional pigment and centrifuging the washed pellet, a supernatant therefrom containing additional pigment.  
     
     
         15 . The method recited in  claim 14 , further comprising the steps of repeated pellet washing and centrifuging steps to maximize pigment extraction.  
     
     
         16 . The method recited in  claim 1 , wherein the homogenizing step comprises applying pressure to the at least one of the retentate and the in-line pulp, a level of the applied pressure sufficiently large to achieve pigment extraction and sufficiently low to avoid the generation of sufficient heat to compromise pigment stability and cause an undesirable odor in the formed slurry.  
     
     
         17 . An aqueous method of enhancing the color of citrus fruit juice comprising the steps of: 
 separating citrus fruit into in-line pulp and juice;    separating the juice into clarified juice and retentate;    homogenizing at least one of the retentate and the in-line pulp to form a slurry;    recovering the pigment from the slurry; and    adding the pigment to citrus fruit juice to enhance a color thereof.    
     
     
         18 . The method recited in  claim 17 , wherein the citrus fruit separating step comprises the step of sending the citrus fruit through an extractor and a finisher to produce the in-line pulp and juice.  
     
     
         19 . The method recited in  claim 18 , wherein the juice separating step comprises the step of filtering the juice.  
     
     
         20 . The method recited in  claim 19 , wherein the filtering step comprises ultrafiltration.  
     
     
         21 . The method recited in  claim 18 , further comprising the step of debittering the in-line pulp prior to the homogenizing step.  
     
     
         22 . The method recited in  claim 21 , wherein the debittering step comprises rinsing with water having a temperature sufficiently high to remove bitter compounds from the in-line pulp and sufficiently low to prevent damage to the pigment.  
     
     
         23 . The method recited in  claim 22 , wherein the bitter compounds comprise naringin and limonin.  
     
     
         24 . The method recited in  claim 22 , wherein the temperature comprises approximately 45° C.  
     
     
         25 . The method recited in  claim 17 , wherein the recovering step comprises washing the slurry with an aqueous solution and centrifuging the washed slurry, the pigment remaining in a supernatant of the centrifuging step.  
     
     
         26 . The method recited in  claim 25 , wherein the washing and centrifuging steps comprise repeated cycles of washing and centrifuging the slurry.  
     
     
         27 . The method recited in  claim 25 , further comprising the step of filtering the supernatant.  
     
     
         28 . The method recited in  claim 17 , further comprising the step of subjecting the homogenized retentate to centrifugation, a supernatant therefrom containing the pigment.  
     
     
         29 . The method recited in  claim 28 , further comprising the step of filtering the supernatant.  
     
     
         30 . The method recited in  claim 28 , further comprising the steps of washing a pellet from the centrifuging step with an aqueous solution to extract additional pigment and centrifuging the washed pellet, a supernatant therefrom containing additional pigment.  
     
     
         31 . The method recited in  claim 30 , further comprising the steps of repeated pellet washing and centrifuging steps to maximize pigment extraction.  
     
     
         32 . The method recited in  claim 17 , wherein the homogenizing step comprises applying pressure to the at least one of the retentate and the in-line pulp, a level of the applied pressure sufficiently large to achieve pigment extraction and sufficiently low to avoid the generation of sufficient heat to compromise pigment stability and cause an undesirable odor in the formed slurry.