Abstract:
A culture of lactobacilli is added to and heated with a protease hydrolyzed beef juice concentrate at a temperature of from 50° C. to 60° C. to hydrolyse polypeptides contained in the protease hydrolyzed concentrate to enhance the flavor of the concentrate.

Description:
BACKGROUND OF THE INVENTION 
     The present invention relates to a process for enhancing the flavor of a natural beef juice or beef stock. 
     European Patent Application Publication No. 223560 describes a method for flavor control of a protein hydrolysate which comprises selecting a proteinaceous feedstock, subjecting said feedstock to a primary enzymatic hydrolysis with a proteinase to produce a primary hydrolysate including bittering substances characterised by subjecting said primary hydrolysate to a secondary enzymatic hydrolysis with an extract containing aminopeptidase enzymes, said secondary enzymatic hydrolysis acting to convert said bittering substances to, at least, flavor-neutral substances. 
     SUMMARY OF THE INVENTION 
     We have found that by using a natural food such as beef juice as the substrate, rather than a more purified selected proteinaceous feedstock, and a culture of a food-grade microorganism which is capable of producing aminopeptidases, instead of an extract containing aminopeptidases, we can obtain a flavor having at least five times the intensity of a normal beef flavour. 
     Accordingly, the present invention provides a method for enhancing the flavor of a natural beef juice concentrate which comprises hydrolysing a beef juice concentrate with a protease and incubating the hydrolysed beef juice concentrate with a culture of a food-grade microorganism which is capable of producing aminopeptidases. 
     Preferably, the hydrolysis with a protease is carried out before the incubation step. 
     The beef juice concentrate may be any kind of concentrated beef juice, for example, beef stock. 
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
     Any protease may be employed in the process of this invention, for example, acid protease, fungal protease, AlCALASE, Neutrase, Bromelain, or trypsin. The amount of protease used may be from 0.6 to 48 Anson Unit (AU)/kg and preferably from 2.4 to 24 AU/kg based on the weight 
     The Ph of beef juice concentrate. The pH of the protease treatment may be from 3 to 11 and preferably from 4.0 to 9.0. The temperature of the protease treatment may be from 50° to 60° C. and preferably from 52.5° to 57.5° C. 
     The duration of the treatment with the protease may vary widely depending, for example, on the particular protease used, the concentration of the protease and the temperature. Preferably the duration is from 30 minutes to 5 hours, especially from 1.5 to 2.5 hours. 
     If desired, the hydrolysed beef juice may be pasteurised before cooling. 
     The food-grade microorganism may be selected from, for instance, yeasts, molds, bacteria such as streptococci, bacilli or lacto bacilli, preferably Lactobacillus helveticus. The food-grade microorganism may produce intracellular peptidases which may be secreted or may not be secreted in any substantial amount across the cell membrane. When the peptidases remain intracellular, it is thought that bitter tasting polypeptides permeate into the cells where they are hydrolysed by the peptidases to give debittered substances which are permeated back out of the cells into the slurry. 
     The peptidases produced by the food-grade microorganism are usually dipeptidase, tripeptidase, aminopeptidase and carboxypeptidase. 
     Advantageously, the food-grade microorganism may be heat-shocked before incubation, e.g., treated at 55°-70° C. for up to a few minutes to render the cell walls porous and to reduce their ability to produce acids from free sugar. 
     The cell concentration of the food-grade microorganism is conveniently from 10 3  to 10 10  cells/g and preferably from 10 4  to 10 8  cells/g. 
     The incubation temperature is conveniently from 40° to 60° C. and preferably from 50° to 57.5° C. The duration of the incubation is suitably from 2 to 30 hours, preferably from 3 to 24 hours and especially from 4 to 16 hours. 
     The pH during the incubation may be from 4 to 7.5 and preferably from 5.5 to 7.2, the optimal pH depending upon the nature of the substrate. Reduction of the pH may be obtained by employing food-grade acids, e.g., lactic or malic acid. 
     The incubation may be carried out without agitation but preferably with agitation, for example stirring from 50 to 300 rpm. 
     After incubation, the debittered protein may be pasteurised, e.g., at a temperature from 65° C. to 90° C. over a period of from 10 to 30 minutes, preferably with agitation or by high temperature short time treatment, followed by cooling. 
     The final beef flavored product may be dried and, as such, can be stored at room temperature. If the final product is in the liquid form, it should be stored under frozen or refrigerated conditions depending on the length of storage desired. 
     EXAMPLE 
     The following Example further illustrates the present invention. 
     EXAMPLE 
     100 parts of beef juice concentrate containing 40% solids was heated to 55° C. and the pH adjusted to 7.0 with 20% KOH. 0.5 parts of ALCALASE 2.4 L (a protease obtained from Novo) were added and the mixture hydrolysed at 55° C. for 2 hours while maintaining the pH at 7.0 with 20% KOH. The hydrolysate was pasteurised at 90° C. for 20 minutes and cooled to 30°-35° C. 
     The pH of the hydrolysate was then adjusted to 6.0 with 20% malic acid and 3% of washed lactobacillus helveticus culture (Miles Laboratories) were added and incubated at 55° C. for 12 hours. The pH was readjusted to 6.5-6.8 with 20% KOH and the product was pasteurised at 80° C. for 15 minutes. 
     The flavor produced had at least five times the intensity of normal roast beef flavour as determined by the concentration of free amino acids generated by the treatments as shown in the Table below. 
     
                       TABLE______________________________________      Free Amino Acid  flavor IntensityTreatment  Concentration (FAA)*                       Increase Potential______________________________________Beef juice 2.15 mg/ml       ControlconcentrateAfter proteolysis      4.94 mg/ml       2.29×After debittering      13.72 mg/ml      6.39×______________________________________ *FAA expressed as tyrosine equivalent