Abstract:
The invention concerns ready-to-use glazing agents with the composition: 
     5-25 wt. % of liquid vegetable oil; 
     5-15 wt. % of casein or its salts; 
     0.005-10 wt. % of emulsifier; 
     0.1-8.0 wt. % of a compound giving a browning upon heating, preferably by a Maillard-type of reaction and 
     balance: water. 
     The composition is sterilizable and has a shelf-life after sterilization of more than 3 months.

Description:
This is a continuation of application Ser. No. 08/088,653, filed on Jul. 9, 1993, now abandoned. 
    
    
     The invention is concerned with glazing agents that are ready to use. 
     BACKGROUND OF THE INVENTION 
     Glazing agents that are not ready to use are known from, e.g., EP 205,195. According to this reference, a glazing agent can be provided comprising a homogenized emulsion of a protein, an edible oil, water and a thin-boiling starch. The thin-boiling starch is applied in order to regulate the viscosity of the emulsion. 
     However, the keepability of such a glazing agent was not sufficient. Although this keepability could be increased by drying the glazing agent, the resulting product was no longer ready to use. 
     Therefore, we have performed a study in order to find a glazing agent that: 
     is ready to use; 
     has the required spreadability, i.e. viscosity; 
     shows good keepability. 
     SUMMARY OF THE INVENTION 
     As a result of this study, we have found that ready-to-use glazing agents fulfilling the above-mentioned requirements have the following composition: 
     They are fat-in-water emulsions comprising: 
     1-25 wt. %, preferably 5-15 wt. %, of a liquid vegetable oil; 
     5-15 wt. %, preferably 8-11 wt. %, of casein or one of its salts; 
     0.005-10 wt. % of an emulsifier, preferably 0.01-1.0 wt. % of an emulsifier, in particular one selected from the group of fatty acid monoglycerides and diglycerides from C 14  -C 22 , preferably saturated and/or unsaturated C 16  -C 18  fatty acids; 
     0.1-8.0 wt. % of a composition giving a browning upon heating, preferably a Maillard-type reaction, such as lactose, or a milk product containing lactose, amounts of 0.3-3 wt. % being preferred, while suitable milk products are skimmed milk powder or buttermilk powder; 
     balance: water 
     DESCRIPTION OF PREFERRED EMBODIMENTS 
     The liquid vegetable oil being defined as an oil being liquid up to 30° C. (so: N 30  ≈0). So, our composition is free of starch or modified starch. 
     The viscosity of the composition at 20° C. is 1-10 5  mPa.s, preferably 20-200 mPa.s. 
     The keepability of these compositions is very satisfactory as the compositions can be sterilized by UHT treatment, i.e. 1-30 seconds at 130°-160° C. After this treatment, the viscosity of the glazing agent remains within the specifications, while keepabilities (ambient shelf-lives) are obtained for at least 3 months. 
     The best results are obtained by applying a liquid vegetable oil with a solid fat index at 20° C. of less than 7.0, a preferred oil being a medium-hardened soybean oil. 
     This liquid oil can also comprise some amount, in particular 2-15 wt % on oil, of a hydrogenated vegetable fat. A preferred fat being hydrogenated palm oil, in particular PO-45. Application hereof improves the viscosity and the stability of the product. 
     It was further found, that the desired colouring, due to heating of a food product provided with a layer of our glazing agents, could be obtained, when our compositions contained 0.1-8.0 wt % of a compound or a mixture that can give a a browning upon heating, preferably by a Maillard-type of reaction. Browning can be obtained by Maillard reactions (amino sugar reactions), by caramelization of sugars or by oxidative reactions. Examples of Maillard compositions are lactose, preferably in combination with a protein-source, such as milk products containing lactose. 
     The stability of the water-continuous emulsion is greatly dependent on the droplet size of the fat droplets in the emulsion. Droplet sizes of less than 5.0 μm, in particular of 0.5-2.0 μm, are preferred. 
     We also found that the presence of some egg-yolk in our composition leads to an improved emulsion stability. Therefore, we prefer that our ready-to-use glazing agents also comprise 1-10 wt % in particular 2-8 wt % of an egg-yolk composition. Preferred egg yolk compositions contain some salt, in particular 5-15 wt % (on egg yolk). 
     The glazing agents according to the invention can be applied on normal dough (i.e. of ambient temperature) and on frozen dough. Baking of the dough, with or without thawing of the dough before baking, leads to excellent gloss, appearance and colour of the baked products. 
     The glazing agent is normally applied in amounts of 30-100 mg/cm 2 . Spraying or atomizing are standard techniques for the distribution of the glazing agent; however, brushing should also be possible. 
     Although above products display excellent glazing properties, we found that upon use (by spraying) of the glazing agent over the product to be baked, which normally is performed on a baking-sheet, the part of the material, that is in direct contact with the hot baking-sheet is very difficult to remove from the baking sheet after baking of the product. 
     In order to improve the cleaning abilities of our glazing agents, we found that addition of 0.05-2.5 wt % of a pyrophosphate, in particular 0.1-1.5 wt %, resulted in the required improvement. Preferred pyrophosphates are the alkali-pyrophosphates, preferably sodium pyrophosphate. 
     Good results have been obtained by any of the following procedures: 
     I 
     1. making a dough, moulding and proofing it; 
     2. coating it with glazing agent; 
     3. baking of fresh product. 
     II 
     1. making a dough and moulding it; 
     2. coating it with glazing agent; 
     3. baking of fresh product. 
     III 
     1. making a dough, moulding and proofing it; 
     2. coating it with glazing agent; 
     3. freezing of the coated product; 
     4. frozen storage: 3 weeks; 
     5. baking of the frozen product without thawing. 
     IV 
     1. making a dough and moulding it; 
     2. coating of the dough with glazing agent; 
     3. freezing of the coated dough; 
     4. frozen storage: different periods; 
     5. thawing of the frozen, coated dough; 
     6. proofing of the product of 5); 
     7. baking of the product of 6). 
     V 
     1. making a dough and moulding it; 
     2. coating it with glazing agent; 
     3. freezing of the dough; 
     4. frozen storage: different periods; 
     5. thawing; 
     6. baking of the coated, thawed, frozen dough. 
     In process IV, relative humidity has an impact on the product properties. It was found that too high an R. H. (i.e. &gt;60%) led to relatively worse products. 
     It is also possible to apply the glazing agent according to the invention for the preparation of microwavable, proofed, baked, frozen and coated doughs. 
    
    
     EXAMPLES 
     I A pre-mix was made in water of 80° C. containing the water, skimmed milk powder and sodium caseinate. 
     Simultaneously, a mixture of unsaturated mono- and diglycerides was dissolved in soybean oil (N 20  ≈0). 
     The fat mixture was added to the water phase and the mixture was subjected to Ultra Turrax mixing for 5 minutes. The D 3 .2 (= droplet size) was 3.8 μm. 
     The composition was sterilized by indirect heat treatment (8 seconds at 140° C.). 
     The composition of the resulting glazing agent was: 
     
         ______________________________________           wt. %______________________________________  Water    80.0  Na-caseinate           10.0  SMP      2.0  BO       7.9  Emulsifier           0.06______________________________________ 
    
     The viscosity (η 20 ) of the sterilized product was about 200 mPa.s. 
     II The procedure of Example I was repeated; however, the Ultra Turrax mixing was followed by a pressure-homogenization procedure (at about 50 bar). This resulted in a product having a droplet size before sterilization of about 1.9 μm. The η 20  of the sterilized product was about 100 mPa.s. 
     III The products were evaluated on the following product types: Danische Brotchen, croissants, puff pastry sheets and &#34;gevulde koeken&#34; (≈ almond paste cakes). 
     Therefore, the procedures mentioned above (I-V) were applied, as illustrated in Table I. 
     
                                           TABLE I__________________________________________________________________________    Products    Yeast-leavened               Yeast-leavened                         Laminated dough:                                   Short dough:    rich dough:               laminated dough:                         Puff pastry                                   `gevulde koeken`    `Danische Brotchen`               Croissants                         sheets    (≈ almond paste cakes)Procedure    Sample number__________________________________________________________________________I        1          2II                            3         4IIIFrozen storage:3 weeks             5IVFrozen storage:2 weeks  63 weeks             7/890% -- RH    6          745% -- RH           82 weeks                       9         10__________________________________________________________________________ 
    
     In Tables II and III a comparison is made between coatings obtained with the composition according to the invention, coatings obtained from whole egg and coatings obtained with a commercially available, not ready-to-use mix &#34;Ovex bakglans&#34; (ex Zeelandia). 
     
                                           TABLE II__________________________________________________________________________         Whole egg                OVEX  Sample number         reference                bakglans                      1   2  3   4  5  7  8__________________________________________________________________________`Danische Brotchen`Gloss remarks:         3      2     3Appearance remarks:         3      2     3Colour remarks:         3      3     3Mouthfeel crust remarks:         3      3       3.5CroissantsGloss remarks:         3                4         4  3  4Appearance remarks:         3                4         4  3  4Colour remarks:         3                3         3  3  3Mouthfeel crust remarks:         3Puff pastry SheetsGloss remarks:         3      3            3Appearance remarks:         3      3            3Colour remarks:         3      3            3Mouthfeel remarks:         3        3.5          3.5`Gevulde Koeken`(≈ almond paste cakes)Gloss remarks:         3      3                3Appearance remarks:         3      4                4Colour remarks:         3      4                4Mouthfeel remarks:         3      3                3__________________________________________________________________________SCALE      1          - 3            - 5__________________________________________________________________________Gloss      less         reference      more                   (whole egg)Colour     less         reference      more                   (whole egg)Appearance worse        reference      better      than ref.    (whole egg)    than ref.Mouthfeel crust      less         reference      tougher      tough        (whole egg)__________________________________________________________________________ 
    
     
                       TABLE III______________________________________Type of glazing             Glazingagent                       according toSample number OVEX bakglans the invention______________________________________2 weeks&#39; storage6             poor results: poor results:         very dark surface                       very dark         which showed  surface which         strange bubbles                       showed strange                       bubbles9             smooth surface:                       smooth surface         light-yellow  yellow-brown         colouring; good                       colouring; good         appearance    appearance10            smooth surface                       smooth surface         light-yellow  light-brown         colouring; good                       colouring; good         appearance    appearance______________________________________ 
    
     EXAMPLE IV 
     A pre-mix was made in water of 80° C. containing the water, skimmed milk powder and sodium caseinate. 
     Simultaneously, a mixture of Na-pyrophosphate, unsaturated mono- and diglycerides was dissolved in soybean oil (N 20  ≈0). 
     The fat mixture was added to the water phase and the mixture was subjected to Ultra Turrax mixing for 5 minutes. The D 3 .2 (= droplet size) was 3.8 μm. 
     The composition was sterilized by indirect heat treatment (8 seconds at 140° C.). 
     The composition of the resulting glazing agent was: 
     
         ______________________________________          wt %______________________________________Water            80.5Na-caseinate     9.0SMP              2.0BO               7.94Emulsifier       0.06Na-pyrophosphate 0.5______________________________________ 
    
     The viscosity (n 20 ) of the sterilized product was about 200 mPa.s. 
     An aluminium baking sheet was provided with a thin fatlayer. On this fatlayer a layer of the glazing composition was brought, using a pensil. The system so obtained was heated for 15 min. in an oven at 190° C. 
     Above procedure was repeated using 1) a whole egg glazing composition and 2) a glazing agent as above, but without Na-pyrophosphate. 
     The baking sheets were cooled for 30 min. after removal from the oven. Cleaning was performed by soaking for 3 min. with water of 55° C. 
     
                       TABLE IV______________________________________agent            cleaning results______________________________________whole egg        ++glazing agent without            --pyrophosphateglazing agent with            ++pyrophosphate______________________________________