Meringues

Plant Cell Culture. Air-lift bioreactors have been favored for plant cell systems since these cultures were first studied (4). However, they can give rise to problems resulting from flotation of the cells to form a meringue on the top. It is interesting to note that some reports indicate that stirred bioreactors do not damage such cells (4). 

Chlorides have probably received the most study in relation to their effect on corrosion. Like other ions, they increase the electrical conductivity of the water so that the flow of corrosion currents will be facilitated. They also reduce the effectiveness of natural protective films, which may be permeable to small ions the effect of chloride on stainless steel is an extreme example but a similar effect is noted to a lesser degree with other metals. Turner" has observed that the meringue dezincification of duplex brasses is affected by the chloride/bicarbonate hardness ratio. 

It is possible to write about designing a system to produce a stable foam on the basis of accumulated scientific knowledge. However, notably, the vast majority of food systems were the product of empiricism and serendipity It remains to be seen if advances in scientific understanding can produce any food foam that is as successful as a meringue. 

In sponge cakes made without chemical leavening, expansion in the oven can only come from the water and the air present. Similarly, meringues expand in the oven as the water evaporates. 

An interesting side effect of the presence of ovatransferrin in egg whites is the custom, long established before any rational explanation, of beating egg whites in copper bowls to stabilize the foam (as in meringues, etc.) The copper complex of ovatransferrin stabilizes the protein of egg white against denaturation and thus Stabilizes the foam.111... 

These foams can also have complex rheological properties. Specialized methods have been developed to deal with the pronounced slip that can be exhibited by food foams [823]. Some food foams exhibit strong yield stresses, as in products that have been whipped to the stiff peak stage. Whipping air into egg white is an example. Baking the stiff foam that results produces meringue. 

Gelation is the conversion of a liquid to a disordered solid by formation of a network of chemical or physical bonds between the molecules or particles composing the liquid. The liquid precursor is called the sol, and the solid formed from it is the gel. Gels can be as mundane as the epoxy glue used to mend a child s toy, or they can be as sublime as the jellies, meringues, and custards that delight the mavens of haute cuisine. 

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