Flavorants derived from fats and oils
CROSS REFERENCE TO RELATED APPLICATION 
     This is a continuation of application Ser. No. 07/239,789 filed Sep. 1, 1988, now U.S. Pat. No. 5,079,017. 
    
    
     BACKGROUND OF THE INVENTION 
     The present invention relates to a process for the preparation of a flavouring composition. 
     In U.S. Pat. No. 4,571,342 there is described a process for the preparation of a flavouring composition with a charcoal broiled flavour which is prepared by subjecting a film of fat or oil to a temperature within the range of from 285° C. to 475° C. in the presence of oxygen for a period of time effective to develop a charcoal broiled flavour and collecting the resultant fat or oil. In the process described in this patent, the film of the fat or oil is subjected to these temperatures in a continuous feed thin film reactor. However, in such a reactor, since fresh material is constantly being added, it is impossible to obtain fractions that differ in composition and flavour since, for any moment in time, the same degree of heating is taking place. Moreover, since the fat or oil is in the form of a film, in order to obtain a desirable flavour, it is essential that the duration of the treatment at these temperatures is extremely short because, whether in a continuous or a batch reactor, at such high temperatures, the film of fat or oil would rapidly become pyrolysed and polymerised and would have a distinctly unpleasant flavour. 
     U.S. Pat. No. 4,094,997 describes a process for preparing a beef flavour substance which comprises preheating an animal fat at 130° to 220° C., mixing the preheated fat with brewed soy sauce and heating at 130° to 220° C. for 5 to 30 minutes, which mixture may afterwards be distilled with steam or with vapour of an organic solvent. 
     SUMMARY OF THE INVENTION 
     We have found, surprisingly, that a variety of desirable flavours, distinctly different from those obtained by the processes of U.S. Pat. Nos. 4,571,342 and 4,094,997 can be obtained by distilling a fat or oil starting material which is in the form of a liquid pool wherein the heating may be carried out at a temperature from 300° to 475° C. for prolonged periods in a special batch type apparatus. In U.S. Pat. No. 4,094,997 the volatiles produced by the initial heating of the fat at 130° to 220° C. and the beef flavour molecules formed by distillation only after reactions have taken place between the fat and the soy sauce, are very different from the volatiles formed in our invention by heating only fats or oils at a temperature from 300° to 475° C. and simultaneous distillation of the flavourant molecules. 
     Accordingly, the present invention provides a process for the preparation of a flavouring composition which comprises subjecting a fat or oil or any mixture of two or more fats or oils thereof in the form of a liquid pool to a temperature of from 300° C. to 475° C. in the presence of oxygen in a batch type apparatus provided with gas inlet and outlet ports and means for collecting the volatiles distilled. 
     Conveniently, oxygen enters the gas inlet port, exits from the gas outlet port carrying with it the volatiles distilled and preferably passes through the collecting means before being vented to the atmosphere. 
     The recovery of the volatiles distilled in the reaction may be achieved by any effective conventional means such as a cold trap, a condensor or a water trap. If desired, several traps may be used. For example, when a condensor 
     is used, it may be cooled, for instance, to from 4° C.-10° C. by circulating water or refrigerant through it. 
     Preferably the batch type apparatus is provided with a cold trap or condenser and a cold water trap wherein the oxygen exiting from the outlet passes through the cold trap and the cold water trap before being vented to the atmosphere. The batch type apparatus should be capable of withstanding the high temperatures involved, and a bomb reactor is particularly suitable. The use of pressure is not excluded. 
     DETAILED DESCRIPTION OF THE INVENTION 
     The fat or oil may be any animal or vegetable fat or oil or any glyceride of a fatty acid, e.g., beef fat, beef tallow, chicken fat, fish oil such as cod liver oil, safflower, seed oil (high oleic), linseed, olive, blackcurrant seed, grapeseed, low erucic acid rapeseed, coconut, peanut, cotton seed, palm, corn, partially hydrogenated soy oil, or any mixtures thereof. If desired, the fat or oil may be used in admixture with one or more fatty acids, for example, lauric acid, palmitic acid, stearic acid, oleic acid, or linoleic acid or with fatty acid mixtures such as butter acids, dairy acids cheese acids, enzyme hydrolysed vegetable oils, such as olive oil or coconut oil, or enzyme hydrolysed animal fats. Examples of such mixtures are a mixture of beef fat and oleic acid in a ratio of from 2:1 to 4:1 and a mixture of chicken fat and linoleic acid in a ratio of from 2:1 to 6:1. 
     By &#34;in the form of a liquid pool&#34; we mean that the fat or oil starting material should not be in the form of a film, i.e., it should not be in the form of a thin layer, sheet or droplets, and particularly should not be a film with a thickness of less than 5 mm. Conveniently, the fat or oil starting material lies as a liquid or melted pool at the bottom of the reactor 
     If desired, flavour precursors may be added to the fat or oil prior to the heat treatment to enhance the flavour, e.g., sulphur-containing compounds such as cysteine, cystine, methionine, thiamine, hydrogen sulphide, or sulphur-containing extract from vegetables such as onions, garlic or members of the BRASSICA family. 
     Preferably, the temperature to which the fat or oil or mixtures thereof is subjected is from 310° C. to 400° C. and especially from 325° C. to 375° C. The time of the treatment may be from a few seconds, e.g., 10 seconds to several hours, more usually from 1 minute to 6 hours, and preferably from about 5 minutes to 4 hours. The actual period of time chosen may be the time effective to produce the desired flavour notes which are generally roasted, grilled and smokey, longer periods generally producing more roasted flavour notes. 
     The flavourants created by the process of the present invention depend on the fat or oil employed, and the use of the batch type apparatus is especially advantageous because the volatiles distilled or carried by the air flow out of the reactor and can be collected and used as a flavourant. In addition, distillates offer the advantage of fractionating the volatiles with time to produce a broader range of flavourants, each having a different flavour, which can be used either individually or in combination with other fractions to obtain an even broader range of flavourants. Distillates offer another advantage in that any polymeric materials, which are objectionable yet unavoidable side products in high temperature reactions of fats or oils, are left behind in the reactor and are not present in the flavourants. Moreover, there is usually a significant amount of water distilled over with the volatiles generated in a batch-type apparatus, and if this water is separated from the volatiles, it can also be used as a flavourant. 
     Thus, by varying the initial fat or oil material employed, the reaction temperature, the intervals of time used for collecting the volatiles and the specific combinations of the fractions, a myriad number of flavour notes can be generated from a single fat or oil. In addition, two or more fractions obtained from different processes according to this invention may be used as flavourants. 
     By the process of the present invention, flavours can be obtained which can be specifically targeted towards a wide variety of meats, chicken, fish or cheese depending on the starting fat or oil material employed, the temperature used and the specific times that the volatile fractions are taken as well as the combinations of the fractions. 
     The oxygen present in the treatment is conveniently obtained from air, and preferably the air is passed through the fat or oil material, e.g., by bubbling, at a rate of from 10 to 5000 ml/min, especially from 15 to 3000 ml/min per 100 g of fat or oil material. The use of pressurised reactions to provide sufficient oxygen is not excluded. 
     The flavouring composition produced by the process of the present invention may be used in the powdered form which may be obtained by spray drying in admixture with carriers which can encapsulate the flavouring composition, e.g., gum arabic, malto-dextrin modified, food starches, dextrins or a protein such as gelatin. Advantageously, a solution or an emulsion of the flavouring composition and carrier is formed which is dried, for example, by spray-drying. The amount of flavouring composition present is usually from 2.5% to 50% and preferably from 5% to 30% by weight based on the total weight of the flavouring composition and the carrier. Since the distillates produced are very volatile, preferably the techniques used to encapsulate them should substantially inhibit reactions which might take place with other materials that the flavourant may subsequently be blended with. 
     The flavouring composition can be used by itself, dispersed in a fat, or in admixture with a carrier, for incorporation into, or coating onto a wide variety of foodstuffs to impart the specific flavour, e.g., meats, sauces, soups, etc. 
    
    
     BRIEF DESCRIPTION OF THE DRAWING 
     The present invention will now be further illustrated by way of example with reference to the accompanying drawing in which FIG. 1 represents a bomb apparatus which may be employed as the reactor. 
    
    
     DETAILED DESCRIPTION OF THE DRAWING 
     Referring to FIG. 1, the apparatus comprises a 600 ml bomb (10), fitted with a stirrer (11), an air inlet (12) and an air outlet (13), surrounded by a bomb jacket (14) provided with a heating element (not shown). The air outlet (13) passes into the top of a cold trap (15) fitted with a tap (16) and an air outlet (17) which in turn passes into the top of a cold water trap (18) containing 400 ml water (19) and fitted with an air outlet (20) to the atmosphere and a tap (21). Both traps (15) and (18) are maintained at a temperature of 4° C. by being immersed in ice-baths (not shown). 
     In operation, 100 g of fat or oil material (22) is introduced into the bomb and air is passed at 2000 ml/min through the air inlet (12) and bubbled through the fat or oil material which is agitated by the stirrer (11) and heated to the appropriate temperature. The air outlet (13) allows the passage of the air and the volatiles distilled from the fat or oil material by gas &#34;stripping&#34;, into the cold trap (15). Any volatiles which pass cold trap (15) can be further collected in the cold trap (18) by passing through the air outlet (17). 
     The volatiles collected in the cold trap (15) are further fractionated by time whereby all the volatile material distilled from the bomb (10) into the cold trap (15) between 0 and 5 minutes is run off from the tap (16) and collected as one flavourant, the volatiles distilled into the trap between 5 and 10 minutes are collected as a second flavourant, those between 10 and 15 minutes are collected as a third flavourant, etc., and further fractions collected until no further volatiles are generated from the bomb. Each fraction collected has a different flavour. A significant amount of water distills over with the fat-soluble volatiles generated in the bomb and this water is separated to give a further flavourant. The volatile material which is collected in the water trap (18) is run off from tap (21) and collected to give yet another flavour. 
     EXAMPLES 
     The following Examples further illustrate the present invention: 
     EXAMPLE 1 
     Using the apparatus illustrated in FIG. 1, 200 grams of chicken fat were placed in the bomb and heated to 350° C. with stirring. Air was passed through at 3100 ml/min. Five minutes after the temperature had reached 350° C., the first fraction was collected and the fractionation was continued as follows: 
     
         ______________________________________                                    
                            Description of                                
Fraction Time    Yield (g)  Organoleptic evaluation                       
______________________________________                                    
1        0-5      4.3                                                     
2         5-11   20.7       white chicken meat                            
3        11-20   32.5       roasting skin                                 
4        20-25   17.6       BBQ chicken                                   
5        25-30   14.6       crispy skin                                   
The combined water                                                        
              9.2       more meaty grill flavour                          
phase                                                                     
Total yield  98.9                                                         
______________________________________                                    
 
    
     15 mg of the above fractions were mixed with 2.8 g of hydrolysed plant protein and hydrated with 240 ml of boiling water. The organoleptic evaluation of the respective fractions with hydrolysed plant protein are described above. 
     EXAMPLE 2 
     By following a similar procedure to that described in Example 1, but using 220 g of rendered bacon pork fat, a comparable series of flavour fractions were obtained as follows: 
     
         ______________________________________                                    
                          Description of                                  
Fraction                                                                  
        Time     Yield (g)                                                
                          Organoleptic evaluation                         
______________________________________                                    
1       0-5       6.5                                                     
2        5-13    35.0     Meaty and brothy                                
3       13-19    23.2     Meaty with pork skin notes                      
4       19-23    11.2     Roasted                                         
5       23-26     8.7     Roasted                                         
The combined water                                                        
              9.8     Coffee-like background note                         
phase                                                                     
Total yield  94.4                                                         
______________________________________                                    
 
    
     Twenty-four mg each of the above flavours were mixed with 2.8 g each of hydrolysed plant protein and hydrated with 240 ml of boiling water. The organoleptic evaluation of respective fractions are described above. 
     EXAMPLE 3 
     By following a similar procedure to that described in Example 1, but using 200 g of Mahaden fish oil and air was passed through at a rate of 2920 ml/min, a series of flavour fractions were obtained as follows: 
     
         ______________________________________                                    
                            Description of                                
Fraction                                                                  
        Time      Yield (g) Organoleptic evaluation                       
______________________________________                                    
1       0-9 min   36.3      Strong fish flavour                           
2        9-13     18.9      Over roasted flavour                          
3       13-16     10.0      Over roasted flavour                          
4       16-19     14.3      Over roasted flavour                          
The combined water                                                        
               8.2                                                        
phase                                                                     
Total yield   87.7                                                        
______________________________________                                    
 
    
     Fifteen mg of the above fractions were mixed with 2.8 g of hydrolysed plant protein and hydrated with 240 ml of boiling water. The organaleptic evaluations are described above. 
     EXAMPLE 4 
     By following a similar procedure as described in Example 1, but using 200 g of beef fat and air was passed through at 3040 ml/min, a series of flavour fractions was obtained as follows: 
     
         ______________________________________                                    
                            Description of                                
Fraction Time    Yield (g)  Organoleptic evaluation                       
______________________________________                                    
1        0-8      9.6                                                     
2         8-19   21.3       Roasted and buttery                           
3        19-29   17.6       Charcoal roasted                              
4        29-36    9.6       Grill and meaty                               
5        36-42    9.0       Gas grilled                                   
The combined water                                                        
             15.2                                                         
phase                                                                     
Total yield  82.4                                                         
______________________________________                                    
 
    
     Fifteen mg each of the above flavour fraction was mixed with 2.8 g of hydrolysed plant protein and hydrated with 240 ml of boiling water. The organoleptic evaluations are described above. 
     COMPARATIVE EXAMPLE A 
     Using the apparatus illustrated in FIG. 1, 200 g of beef fat were placed in the bomb and heated to 250° C. with stirring. Air was passed through initially at a rate of 2030 ml/min and then increased to 3800 ml/min after 60 minutes and only 0.5 g of distillate was collected. A second fraction of 3.0 g was collected after 120 minutes of heating at 250° C. 
     
         ______________________________________                                    
                Air Flow                                                  
Fraction                                                                  
        Time    (ml/min) Yield (g)                                        
______________________________________                                    
         7      2300     0                                                
1       60      3800     0.5 green vegetable note                         
2       60-120  3800     3.0 some meaty notes but green                   
The combined water phase                                                  
                 1.0                                                      
Total yield      4.5 g                                                    
______________________________________                                    
 
    
     Fifteen mg each of the above fractions were mixed with 2.8 g of hydrolysed plant protein and hydrated with 240 ml of boiling water. The organoleptic evaluations are described above. 
     COMPARATIVE EXAMPLE B 
     Using the apparatus illustrated in FIG. 1, 200 g of beef fat were heated to 275° C. with stirring. Air was passed through initially at a rate of 2800 ml/min, then increased to 3800 ml/min after 30 minutes. A first fraction was collected after 52 min and a second fraction was collected after 92 minutes. 
     
         ______________________________________                                    
                            Description                                   
Fraction Time    Yield (g)  Organoleptic evaluation                       
______________________________________                                    
1         0-52   2.1        Roasted                                       
2        52-92   2.5        Slightly grilled beef                         
The combined water                                                        
             2.0        Meaty                                             
phase                                                                     
______________________________________                                    
 
    
     Fifteen mg each of the above fractions were mixed with 2.8 g of hydrolysed plant protein and hydrated with 240 ml of boiling water. The organoleptic evaluations are described above.