Malt beverage having stabilized flavor and methods of production thereof

Abstract

The present invention is directed to a method for stabilizing the flavor of a fermented malt beverage, most particularly a beer, by the addition of one or more inhibitors, blockers, reducing agents or binding agents that inactivate one or more Maillard reaction intermediates that induce staling of the flavor of fermented malt beverages. In preferred such methods, the agents used are reductase enzymes, especially aldehyde reductases, carbonyl reductases, aldose reductases, oxoaldehyde reductases and most particularly oxidoreductases such as isozymes of Old Yellow Enzyme (e.g., OYE1 and 0YE2). The invention is also directed to the fermented malt beverage prepared by such a method, and to the use during the brewing process of reductase enzymes from naturally occurring sources, including those produced by yeasts, to stabilize the flavor of the resulting beer product and to produce a beer having a stable flavor. The invention also relates to cells which have been specifically modified, selected, or genetically engineered to express or secrete a reductase enzyme which may be used during the brewing process to stabilize the flavor of the resulting beer product and to produce a beer having a stable flavor. The invention also provides fermented malt beverages having enhanced flavor stability produced by these methods.

What is claimed is:  
     
         1 . A method of stabilizing the flavor of a fermented malt beverage comprising contacting said beverage with a flavor-stabilizing amount of one or more reductase enzymes, wherein said reductase enzyme is not an oxoaldehyde reductase enzyme.  
     
     
         2 . A method of producing a fermented malt beverage, said method comprising 
 (a) producing a grain malt;    (b) producing a wort from said grain malt;    (c) adding a flavor-stabilizing amount of one or more reductase enzymes wherein said reductase enzyme is not an oxoaldehyde reductase enzyme;    (d) fermenting said wort to produce a fermented malt beverage;    (e) processing said fermented malt beverage to produce a processed fermented malt beverage; and    (f) packaging said processed fermented malt beverage.    
     
     
         3 . The method of  claim 1  or  claim 2 , wherein said reductase enzyme is an oxidoreductase enzyme.  
     
     
         4 . The method of  claim 3 , wherein said oxidoreductase enzyme is selected from the group consisting of an aldehyde reductase enzyme, a keto reductase enzyme, an acetyl reductase enzyme, a primary aminoreductase enzyme, a secondary aminoreductase enzyme and an NADPH-dependent oxidoreductase enzyme.  
     
     
         5 . The method of  claim 2 , wherein said reductase enzyme is added to said wort prior to said fermentation step.  
     
     
         6 . The method of  claim 2 , wherein said reductase enzyme is added to said fermented malt beverage prior to said processing step.  
     
     
         7 . The method of  claim 2 , wherein said reductase enzyme is added to said processed fermented malt beverage prior to said packaging step.  
     
     
         8 . The method of  claim 2 , wherein said reductase enzyme is immobilized on a solid support.  
     
     
         9 . The method of  claim 8 , wherein said solid support further comprises at least one enzyme cofactor.  
     
     
         10 . The method of  claim 9 , wherein said enzyme cofactor is NADH or NADPH.  
     
     
         11 . A genetically modified host cell producing enhanced amounts of at least one reductase enzyme as compared to cells of the wild-type strain of said host cell, wherein said reductase enzyme is not an oxoaldehyde reductase enzyme.  
     
     
         12 . The host cell of  claim 11 , wherein said reductase enzyme is an oxidoreductase enzyme.  
     
     
         13 . The host cell of  claim 12 , wherein said oxidoreductase enzyme is selected from the group consisting of an aldehyde reductase enzyme, a keto reductase enzyme, an acetyl reductase enzyme, a primary aminoreductase enzyme, a secondary aminoreductase enzyme and an NADPH-dependent oxidoreductase enzyme.  
     
     
         14 . The host cell of  claim 13 , wherein said oxidoreductase enzyme is an NADPH-dependent oxidoreductase enzyme.  
     
     
         15 . The host cell of  claim 11 , wherein said host cell is a yeast cell, a bacterial cell, an animal cell or a plant cell.  
     
     
         16 . The host cell of  claim 15 , wherein said yeast cell is a Saccharomyces spp. cell.  
     
     
         17 . The host cell of  claim 16 , wherein said yeast cell is a  Saccharomyces cerevisiae  or a  Saccharomyces carlsbergensis  cell.  
     
     
         18 . The host cell of  claim 15 , wherein said bacterial cell is an  E coli  cell.  
     
     
         19 . A composition comprising an extract or enzymatic digest of the host cell of  claim 11 , said composition comprising one or more reductase enzymes that effectively stabilize the flavor of a fermented malt beverage.  
     
     
         20 . A method for stabilizing the flavor of a fermented malt beverage comprising contacting said beverage with a flavor-stabilizing amount of the extract or enzymatic digest of  claim 19 .  
     
     
         21 . The method of  claim 1  or  claim 2 , wherein said reductase enzyme is substantially purified.  
     
     
         22 . The method of  claim 1  or  claim 2 , wherein said fermented malt beverage is beer.  
     
     
         23 . The method of  claim 1  or  claim 2 , wherein said reductase enzyme is produced by a yeast cell.  
     
     
         24 . The method of  claim 23 , wherein said yeast cell is a Saccharomyces spp. cell.  
     
     
         25 . The method of  claim 24 , wherein said yeast cell is a  Saccharomyces cerevisiae  cell or a  Saccharomyces carlsbergensis  cell.  
     
     
         26 . The method of  claim 23 , wherein said yeast cell has been genetically modified to permit the enhanced production of one or more reductase enzymes which effectively stabilize the flavor of a fermented malt beverage.  
     
     
         27 . A fermented malt beverage in which the flavor of said beverage has been stabilized according to the method of  claim 1 .  
     
     
         28 . A fermented malt beverage in which the flavor of said beverage has been stabilized according to the method of  claim 20 .  
     
     
         29 . A fermented malt beverage produced according to the method of  claim 2 .  
     
     
         30 . The fermented malt beverage of any one of claims  27 - 29 , wherein said beverage is beer.