Abstract:
The invention relates to a method for determining the color of wine from grapes. The method involves digesting the grapes in a pectolytic enzyme solution and a sulfur dioxide solution; diluting the solution with diluted acid and spectrophometric reading of the resulting solutions. The invention also relates to a program that calculates the probable color of the wine based on the spectroscopic data and physical-chemical parameters of the wine.

Description:
FIELD OF THE INVENTION  
         [0001]    The present invention describes a process for the determination of the colour of wine from the grape. This process consists of digestion of the grapes with a solution of pectolytic enzymes and a solution of sulphurous anhydride, dilution of the solution with diluted acid and spectrophotometric reading of the resultant solution and a programme that calculates the wine&#39;s probable colour from spectroscopic data and physicochemical parameters of the wine.  
         BACKGROUND OF THE INVENTION  
         [0002]    The wine&#39;s colour or intensity of colour is mainly caused by anthocyanins. There are trials and methods which take four hours that correlate the anthocyanin content in the grape with that of the wine. However, bulk wine on the market is paid by degree and point of colour and not by mg/l of anthocyanins; furthermore, there is not a high correlation (less than 0.5) between the colour degree and the anthocyanin content. Therefore, at present there is no suitable method for the determination of the intensity of the colour of wine from the grape.  
         OBJECT OF THE INVENTION  
         [0003]    The present invention describes a method to predict the wine&#39;s probable colour, which will be obtained with the grapes analysed in a rapid and highly accurate way, by means of the extraction of colouring matter, spectrophotometric reading and exportation of the spectrophotometric data using a computer programme which, in turn, calculates the wine&#39;s probable colour from the spectrophotometric data and physicochemical parameters of the wine.  
         DETAILED DESCRIPTION OF THE INVENTION  
         [0004]    The process to experimentally obtain the wine&#39;s probable colour consists of two parts:  
           [0005]    a) Extraction of the colouring matter from the grapes and spectrophotometric measurement.  
           [0006]    b) Calculation of the wine&#39;s colour from the spectrophotometric data and physicochemical parameters of the wine by means of a computer programme.  
           [0007]    The seeded grapes can be digested at a temperature below 80° C. in the presence of a solution of pectolytic enzymes and an acid solution of sulphurous anhydride. Once extraction has finished, the mixture is purified, for which various different techniques such as flocculation, filtration or centrifugation can be used. The limpid solution is diluted with a diluted acid, preferably using hydrochloric acid. The resultant solution is read on a spectrophotometer in an interval of wavelengths between 280-700 nm.  
           [0008]    A computer programme calculates the wine&#39;s probable colour from the spectrophotometric data and different analytical parameters of the wine fed into the programme. The analytical parameters are:  
           [0009]    Total acidity  
           [0010]    PH  
           [0011]    Probable degree  
           [0012]    Obtaining an accuracy of IC (real intensity of colour)=PC (Probable colour according to the process)±1.48 
       
    
    
     EXAMPLE  
       [0013]    The invention is described by means of an example which does not limit the scope of the invention.  
       Example 1  
       [0014]    This illustrates the method of extraction and the results obtained for different samples.  
         [0015]    A 1% solution of pectolytic enzymes is added to 100 grams of seeded grapes, which is then triturated and an acid solution of sulphurous anhydride is added. The mixture is stirred at 80° C. for 10 minutes. 2 ml of the sample are centrifuged at 8000 rpm. The sample is diluted by {fraction (1/10)} with diluted hydrochloric acid and a UV spectrum—visible between 200 and 700 nm—is performed.  
         [0016]    Following official methods, the pH, alcohol content and total acidity are determined on the grapes.  
         [0017]    In a parallel way, micro-vinifications are carried out to calculate the real value of the wine&#39;s colour intensity. The results obtained are shown below, where:  
         [0018]    N is the sample number  
         [0019]    P°D is the probable degree  
         [0020]    TA is the total acidity  
         [0021]    D280e and D520e are the absorbancies at 280 and 520 nm of the grape extract obtained for the probable colour determination.  
         [0022]    ICv is the real intensity of colour of the wine obtained.  
         [0023]    PC is the wine&#39;s intensity of colour, calculated according to the method.  
                                                                                                     N   P° D   PH   TA   D280e   D520e   D280v   ICv   PC                                1   14.8   3.8   3.8   136   77   70   9.2   8.96       2   14.2   3.7   4.4   137   82   62   11.4   9.82       3   14.6   3.5   5.5   160   90   67   13.36   12.1       4   13.5   3.7   4.8   155   90   65   13.44   10.82       5   14.7   3.7   5.3   144   76   65   10.49   9.62       6   14.8   3.7   4.4   150   86   62   12.5   10.8       7   13.2   3.6   4.4   176   92   69   13.24   11.51       8   14.8   3.7   4.2   182   86   42   9.52   11.1       9   12.8   3.5   6.2   127   52   57   5.46   6.54       10   14.2   3.4   5.2   163   87   60   10.79   12.3       11   12.5   3.4   5.3   75   21   57   1.95   2.31       12   13.8   3.7   4.4   177   98   67   11.79   12.14       13   14.8   3.8   4.7   171   95   46   11.84   11.84       14   14.8   3.5   4.9   170   90.8   42.5   9.04   12.08       15   14.8   3.7   5.0   176   86   54   13   11.12       16   14.8   3.7   3.7   158   85   47.84   9.30   10.37       17   14.8   3.6   5.0   182   101   50   12.06   13.25       18   13.9   3.5   4.9   150   82   53   9.35   10.7       19   14.2   3.4   6.2   168   90.2   60.7   13.24   12.58       20   13.8   4.1   4.1   163   94   51   9.77   9.94       21   14.8   3.4   5.5   146   66   50   10.95   9.19       22   14.8   3.6   5.2   172   77   54   10.82   10.12       23   14.1   3.6   5.1   182   92   50   10.27   11.93       24   14.0   3.5   5.2   159   68   33   8.14   9.02       25   14.8   3.6   5.2   153   79   62   12.1   10.27       26   14.3   3.6   5.6   174   87   53   12.67   11.61       27   11.8   3.3   6.1   136.6   59   33   8.66   7.61       28   14.7   3.8   4.5   168   96   46   12.97   12.10       29   13.6   3.9   4.2   182   107   46   13.47   12.10       30   14.8   3.6   4.1   176   86   65   8.23   11.21       31   14.8   3.7   4.6   160   79   26   7.80   10.06       32   13.1   3.3   6.2   149   63   57   7.69   8.63       33   13.6   3.5   5.0   159   72   54   10.1   9.24       34   14.2   3.9   4.5   156   68   41   8.51   7.76       35   14.8   3.7   4.5   187   98.8   42   13.96   12.76       36   14.8   3.8   5.0   123   63   44   5.83   7.40       37   14.8   3.6   4.2   188   100   51   13.46   13.24       38   14.8   3.8   4.4   180   98   51   10.34   12.11       39   14.8   3.8   4.5   166   74   59   7.50   8.86       40   14.8   3.7   5.9   141   68   34   9.14   8.53       41   14.8   3.8   4.3   148   81   36   8.52   9.75       42   14.8   3.7   5.5   151   77   39   10.35   9.63       43   14.2   3.7   4.6   151   67   43   10.78   8.41       44   14.8   3.6   3.9   191   105   38   15.25   13.58       45   14.8   3.6   5.5   144   78   64   7.56   10.13       46   14.5   3.6   3.5   206   98   37   10.64   13.09       47   13.5   3.6   5.5   146   71   58   9.32   9.02       48   12.9   3.7   5.1   141   80   49   9.29   9.39       49   14.8   3.8   4.7   195   105   53   11.48   13.05       50   13.1   3.7   4.4   155   80   49   9.67   9.39       51   12.4   3.7   3.8   165   87   43   9.37   9.96       52   14.0   3.6   5.1   211   93   50   12.5   12.53       53   13.6   3.7   4.6   160   88   29   8.68   10.68       54   14.8   3.9   4.1   194   97   49   11.00   12.01       55   14.8   3.7   4.4   161   83   58   10.0   10.41       56   14.6   3.9   4.0   162   100   60   12.06   11.50       57   14.7   3.6   4.9   212   111   65   12.24   15.23       58   13.8   3.9   6.0   155   84   47   7.79   9.92       59   14.2   3.7   4.6   164   81   47   9.91   10.17       60   13.9   3.5   6.0   133   59   45   3.70   7.60       61   13.2   3.7   4.6   148   61   69   5.93   7.28       62   14.8   3.7   4.6   170   74   31   8.82   9.46       63   14.8   3.7   4.6   161   64   23   10.00   8.09       64   14.8   3.7   4.6   182   88   70.2   12.17   11.35       65   14.8   3.8   4.2   182   79   62   10.31   10.03       66   12.6   4.0   4.1   160   84   67   9.66   8.91       67   13.7   3.6   4.6   171   74   65   10.76   9.50       68   14.5   3.7   5.1   153   63   65   9.22   7.97       69   14.5   3.6   5.0   160   75   62   10.83   9.69