Have you ever wondered how easy is it to make Chocolate Mousse and Ribena Sorbet? It only requires a few key ingredients and you can actually do it in the comforts of your home. Science plays an important role in the creation of chocolate mousse and sorbet whereby there a certain chemical and physical processes which help to give the food dish that unique texture and flavor. In this workshop, we were given a short lecture on Molecular Gastronomy by Dr Linda Sellou before giving the opportunity to hands on in the preparation of the two desserts. Molecular Gastronomy is a sub-discipline of food science which investigates the physical and chemical transformation of ingredients that occur during the cooking process. Cooking and Science were considered very different fields of study in the past, but there has been a growing trend of people who are taking interest in the study of science behind every food dish.
Chocolate Mousse
The preparation of chocolate mousse only uses two main ingredients: Dark chocolate and water. At first I was quite puzzled at the fact that it requires so little ingredients however the process of mixing the chocolate with the water plays an important role in giving the chocolate mousse airy and creamy texture. Each group was given a different kind of dark chocolate where it varied based on the content level of cocoa and sugar. The following picture shows the chocolate brand and type that we got:
The scientific process which plays a key role in the creation of chocolate mousse is known as Emulsion which refers to a dispersion of droplets of one liquid (oil) in another (water) which is not soluble or miscible. Upon mixing, the water and oil separate into two distinct layers and a group of small molecules known as emulsifiers which are present at the water-oil boundary help to bind the 2 phases together. Dark chocolate contains cocoa fat, sugar, cocoa powder, soy lecithin (an emulsifier), and a small amount of water. When hot water is added and the chocolate is melted, an emulsion system is formed. The hot water becomes the continuous phase, and oil (melted cocoa fat) becomes the dispersed phase forming a oil-in-water emulsion. Whisking introduces air cells inside this emulsion, the cocoa fat molecules then move around and coat the air cells. When cooled down over an ice bath, oil molecules solidify into fat crystals hence trapping the air cells permanently. That’s how the chocolate-water mixture turns airy and increases in volume and transforms into the Chocolate Mousse.
However, things didn’t really go out as planned as our whisking session took a long time and yielded no results. After a while, our chocolate-water mixture remain water-like despite putting it in a ice bath. There were two possible reasons: Excess of water added or the type of chocolate used was not suitable. In our attempts to hasten the formation of the fat crystals we tried to add dry ice into the mixture which had significant effect on solidifying the mixture.
After our not-so-successful attempt at making the chocolate mousse, we proceeded to make the Ribena Sorbet. Why use dry ice? Dry Ice and Liquid Nitrogen are the two common cooling agents used in creation of sorbet. Dry ice is in fact solid carbon dioxide which is a around -78.5 degrees celsius. The dry ice was first broken up into small pieces in order to increase the surface area of contact of the dry ice with the ribena syrup. When the dry ice comes into contact with the ribena syrup, heat energy will naturally transfer from a region higher temperature to a region of lower temperature. This phenomenon will result in the cooling of the ribena syrup as the heat is transferred to the dry ice which in turn results in the sublimation of the dry ice (evident in the smoke that is being formed). Hence the ribena syrup is lowered to a temperature where the water present freezes thus forming the sorbet.
Overall the workshop taught me how to better appreciate the science behind cooking as there is much more to cooking than just mixing things together. There are in fact chemical processes behind the scene that help to create the texture and flavour that we all love in our food dishes.