Abstract:
The invention relates to food ingredients obtained by fermentation of raw materials of vegetable origin with Saccharomyces boulardii yeast, and to foods containing them.

Description:
FIELD OF THE INVENTION 
     The invention relates to food ingredients obtained by fermentation with Saccharomyces boulardii yeast and to foods containing them. 
     BACKGROUND OF THE INVENTION 
     Yeasts of the genus Saccharomyces are commonly used in many agricultural food industries. 
     Nevertheless, each agricultural food industry utilizes Saccharomyces species in a very specialized manner for the production of fermented foods or drinks. 
     Thus, S. cerevisiae is used in bakery. 
     S. cerevisiae, S. carlsbergensis or S. uvarumare yeasts employed in beer production. S. uvarum is also used in cider making. 
     S. cerevisiae var. ellipsoideus, S. beticus and S. bayanus are well-known yeasts for wine fermentation. 
     S. rouxii is employed in the manufacture of soya sauces and also for rice miso. 
     S. boulardii is a yeast which was isolated from lychee fruits from Indochina back in the 1920s. Since 1962, S. boulardii has been used in Europe and other countries as a probiotic medicinal product having an antidiarrhoeal effect in man. Thus, S. boulardii forms the active principle of the pharmaceutical speciality Ultra-Levure, trade name of Laboratoires Biocodex (92 126--Montrouge, France). 
     Several patents teach us that S. boulardii is an effective medicinal product against some diseases of man: EP-A-0,149,579 and U.S. Pat. No. 4,595,590 for pseudomembranous colitis, EP-A-0,195,870 and U.S. Pat. No. 4,643,897 for amoebiasis. 
     S. boulardii has never been used in the production of fermented foods or drinks. 
     SUMMARY OF THE INVENTION 
     Now, we have discovered that S. boulardii can be used profitably for producing fermented foods and food ingredients, by fermentation of vegetable raw materials containing carbohydrates and proteins. 
     The non-limiting examples which follow will illustrate the invention. 
     In these examples, simple foods are fermented after receiving an inoculum containing S. boulardii. The inoculum may be produced by any known technique of yeast culture. 
     It is possible, for example, to produce the inoculum in the following manner: 
     500 ml of a culture medium containing 10 g of malt, 1 g of maltose, 1 g of commercial yeast extract (Bio Merieux, 69260 Charbonnieres-les-Bains, France) and 500 ml of distilled water are introduced into a flask. The flask is closed with a stopper having two Pasteur pipettes inserted through it, after which the assembly is sterilized at 120° C. for 10 minutes. After cooling to room temperature, the medium is inoculated with 2.5×10 9  live S. boulardii yeast cells. One of the two Pasteur pipettes is connected via its outer end to a tube leading to an aeration pump, and emits bubbles into the culture medium via its inner end. The other pipette does not dip into the culture medium and enables gases to be discharged. The assembly is then placed in an incubator at 37° C. After 48 hours, the culture containing S. boulardii is centrifuged at 4000 rpm for 5 minutes. The supernatant is removed and the pellet is taken up in 30 ml of distilled water. This suspension constitutes the inoculum. The concentration of the inoculum is, on average, 10 9  yeast cells per milliliter. 
     DESCRIPTION OF THE PREFERRED EMBODIMENTS 
    
    
     EXAMPLE 1 
     The following products are introduced into a dough mill of capacity 2 liters having thermostated walls: 
     
         ______________________________________Ground raw wheat           1      kgProtein hydrolysate (Keramine A, trade name                      50     mlof Bretagne Chimie Fine, 56140 - Pleucadeuc,France)Glucose                    100    gWater                      450    mlInoculum                   30     ml______________________________________ 
    
     The temperature of the mill is adjusted to 37° C. The beater of the mill is rotated at 50 rpm for 15 minutes every hour. Water is added during the fermentation in order to maintain the relative humidity above 90% (the relative humidity is measured with a Thermoconstanter, trade name of Novasina A. G., Zurich, Switzerland, hygrometer). 
     After 48 hours of fermentation, the characteristics of the fermented wheat are analysed according to the analytical methods commonly used in the EEC. The wheat thus fermented is compared with the original raw wheat and with the raw wheat mixed with the ingredients, such as the protein hydrolysate, glucose and water, in the same proportions as those used for the fermentation. 
     The results show that S. boulardii has modified the organoleptic, physical and chemical characteristics of the wheat after fermentation: 
     
         ______________________________________                Raw       Wheat        Original                wheat +   fermented        raw     ingre-    with S.        wheat   dients    boulardii______________________________________Odour of       Cereal    Cereal    Fresh                              breadpH (1 g in 10 ml of          6.30      6.20      5.45demineralized water)Dry matter (D.M.) (%)          85.7      57.3      77.7Sucrose (% D.M.)          1.2       1.4       0Proteins (% D.M.)          13.6      13.7      15.0Live yeast cells/g          0         0         3 × 10.sup.7D.M.______________________________________ 
    
     EXAMPLE 2 
     In the same dough mill as in Example 1, adjusted to 37° C., the following products are mixed: 
     
         ______________________________________Soya cake            1      kgGlucose              100    gWater                300    mlInoculum             30     ml______________________________________ 
    
     The beater of the mill is rotated at 50 rpm for 15 minutes every hour for 36 hours. 
     Water is added regularly in order to maintain the relative humidity of the mixture at a level in the region of 90%. 
     After 36 hours, the analyses show that the fermentation with S. boulardii has modified the organoleptic, physical and chemical characteristics of the soya cake: 
     
         ______________________________________          Original  Fermented          soya cake soya cake______________________________________Odour of         Soya cake   Yeast pastrypH (1 g in 10 ml of            6.65        6.33demineralized water)Dry matter (D.M.) (%)            86.6        58.4Starch (% D.M.)  9.0         4.6Total sugars (% D.M.)            10.2        2.6Sucrose (% D.M.) 5.2         0Proteins (% D.M.)            50.9        53.6Live yeast cells/g D.M.            0           3.2 × 10.sup.7______________________________________ 
    
     EXAMPLE 3 
     In the same dough mill as in the previous examples, adjusted to 37° C. the following products are mixed: 
     
         ______________________________________Cereal (50% wheat/50% maize) flakes                      1      kgProtein hydrolysate (Keramine A, trade name)                      50     mlGlucose                    20     gWater                      400    mlInoculum                   30     ml______________________________________ 
    
     The beater is rotated at 50 rpm for 15 minutes every hour for 48 hours. Water is added regularly so as to maintain the relative humidity at 90%. 
     After 48 hours, it is found by analysis that fermentation with S. boulardii has modified the organoleptic, physical and chemical characteristics of the cereal flakes: 
     
         ______________________________________           Original Fermented           cereal   cereal           flakes   flakes______________________________________Odour             Neutral    of Fresh                        breadpH (1 g in 10 ml of             6.60       6.00demineralized water)Dry matter (D.M.) (%)             88.7       60.0Proteins (% D.M.) 13.0       15.1Sucrose (% D.M.)  1.2        0Live yeast cells/g D.M.             0          1.35 × 10.sup.8______________________________________ 
    
     EXAMPLE 4 
     In the same dough mill as in the previous examples, thermostated at 37° C., the following products are mixed: 
     
         ______________________________________Ground pea              500    gGlucose                 10     gYeast extract (BioMerieux)                   10     gWater                   150    mlInoculum                20     ml______________________________________ 
    
     The beater of the mill is rotated at 50 rpm for 15 minutes every hour for 30 hours. 
     Water is added regularly in order to maintain the relative humidity of the mixture at a level in the region of 90%. 
     After the fermentation, the analyses show that S. boulardii has modified the organoleptic, physical and chemical characteristics of the pea: 
     
         ______________________________________           Original Fermented           pea      pea______________________________________Odour             of Bean    Slightly                        alcoholicpH (1 g in 10 ml of             6.48       5.21demineralized water)Dry matter (D.M.) (%)             86.7       65.8Proteins (% D.M.) 23.6       25.2Sucrose (% D.M.)  2.2        0Live yeast cells/g D.M.             0          2.29 × 10.sup.7______________________________________ 
    
     EXAMPLE 5 
     In the same dough mill as in the previous examples, adjusted to 37° C., the following products are mixed: 
     
         ______________________________________Cassava flour          500    gGlucose                10     gYeast extract (BioMerieux)                  10     gWater                  300    mlInoculum               30     ml______________________________________ 
    
     The beater of the mill is rotated at 50 rpm for 15 minutes every hour for 46 hours. 
     Water is added regularly so as to maintain the relative humidity of the mixture at a level in the region of 90%. 
     After the fermentation, the analyses show that S. boulardii has modified the organoleptic, physical and chemical characteristics of the cassava: 
     
         ______________________________________           Original Fermented           cassava  cassava______________________________________Odour             Neutral    AcidicpH (1 g in 10 ml of             6.40       4.60demineralized water)Dry matter (D.M.) (%)             86.6       55.7Proteins (% D.M.) 2.1        3.2Live yeast cells/g D.M.             0          1.1 × 10.sup.8______________________________________