Fats, Soups, Sauces and Emulsions
In my lab today I got to make some soup, biscuits, sauce, vanilla pudding, mayonnaise as well as oil and vinegar salad dressing.
Emulsion is a process where a liquid is dispersed in another liquid with which it is usually immiscible. There are two types of emulsions. Oil-in-water (oil droplets are dispersed throughout the water) and water-in-oil (water droplets are dispersed throughout the oil). These emulsions can be permanent emulsion or temporary emulsion. In my lab we prepared mayonnaise as well as oil and vinegar salad dressing. Mayonnaise is an example of permanent water in oil emulsion. It is very viscous and stable to the point they do not separate. Egg yolk lecithin and continuous agitation makes it a permanent emulsion. Secondly, oil and vinegar salad dressing is an example of temporary emulsion. It is least viscous and stable; they separate on standing when left alone. Air and agitation makes them bind for some period of time.
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It is prepared with wheat flour instead of any other starch. Wheat flour and butter is taken in 1:1 ratio (by weight). It is cooked and hot liquid is gradually added to it and this combination is cooked until it reaches the desired consistency, depending on what kind of sauce is being prepared. There are three types of roux white, blond, and brown. The heating process determines the color of the roux. In the lab we prepared cream gravy using white roux. We melted the butter in pan, added the flour and cooked for two minutes, constantly stirring without browning and then whisked the milk in it until sauce begins to thicken. Note that thickening can be lost by hydrolysis of acid, over stirring and