Hello everyone! Today I’ll be sharing on ice cream and chocolate!

In week 7 we had a workshop on Chocolate and Sorbet, held by Professor Linda Sellou. In this workshop, we learnt a little about molecular gastronomy, the science behind chocolate and ice-cream and even had a hands-on experience on making Chocolate Chantilly, as well as Ribena Sorbet! Let’s start by talking about the Chocolate Chantilly.

Chocolate

Chocolate Chantilly is a mousse/foam-like chocolate dessert that was invented by the father of molecular gastronomy – Hervé This.

To make the Chocolate Chantilly, we only require 2 ingredients: chocolate and hot water! We have to first melt the chocolate in hot water completely, before placing the melted chocolate over another larger bowl containing ice to cool the chocolate down. While cooling the melted chocolate, we continuously whisk the melted chocolate in order to achieve the desired mousse texture.

Initially, when I saw the steps involved, I thought that we will just be re-solidifying the melted chocolate and it seemed pretty pointless to me. But that was because I didn’t understand the science behind the whisking. Whisking the liquefied chocolate is actually the most important step involved in making the Chantilly! What whisking does is that it introduces air into the liquefied chocolate, which is considered to be an emulsion.

Emulsion refers to a mixture of oil and water. Oil and water have different chemical properties which makes them immiscible in each other and when mixed together, they tend to separate into two different layers. However, the addition of emulsifiers may help to solve this problem as these emulsifier molecules position themselves at the oil-water boundary to make sure separation between the 2 layers does not occur.

Chocolate contains oil (in the form of cocoa butter) and an emulsifier (soy lecithin). When hot water is added, the combination of water and oil leads to the formation of an emulsion. The air cells introduced by whisking gets coated by oil particles and when it is cooled, the oil solidifies into fats and traps the air within it. These tiny pockets of air trapped in the mixture leads to an airy, mousse-like Chantilly.

The chocolate our group used was from the brand Chocolat Stella and it’s a dark chocolate made with 100% cacao.

Not sure why our Chantilly did not end up looking like a mousse… maybe too little water was used? But anyway, one word of advice if anybody wants to try this out: please don’t use chocolate with 100% cacao!!!! It was so bitter and one of our classmates actually gagged after trying our Chantilly LOLOLOLOL. Nevertheless, it was still a fun experience!!

I consume chocolate very often but have never really thought much about the process of obtaining it. Through the readings, I’ve learnt a lot more about chocolate. Here are some of the things that I’ve learnt:

  • Most chocolates contain cocoa butter, cocoa powder, sugar and vanilla. In the case of milk chocolate, there is the addition of milk powder.
  • White chocolate is made up of mainly cocoa butter and it is white because it does not contain polyphenols and cocoa liquor, which give chocolates their distinct taste. Hence, some people do not consider white chocolate to be a form of chocolate.
  • Cocoa liquor is the paste from roasted beans and is widely considered to be the heart of chocolate due to the many compounds present which gives rise to the flavor of chocolate.
  • Polyphenols, particularly flavanols, are responsible for the health benefits of chocolate. Such compounds have anti-oxidant properties and can help to combat cancer, lower blood pressure and prevent heart diseases. The higher the cacao content in the chocolate, the greater the anti-oxidant properties. This is why dark chocolate is considered to be healthier than other forms of chocolate.
  • Phenylethylamine, a molecule that stimulates release of dopamine and norepinephrine molecules which give rise to positive emotions, could be found in trace amount in chocolate. This is why people assume that the consumption of chocolate tends to lift our spirits. However, the phenylethylamine actually gets metabolized very quickly in the body, leaving it with insufficient time to have any effects on our brains.
  • Compounds like caffeine and theobromine contributes to bitterness in cocoa beans.
  • To produce chocolate, cacao beans have to first be fermented and roasted. While roasting, the Maillard reaction occurs since the beans contain amino acids, peptides, sugars and carbohydrates.
  • There are 6 different crystal forms of chocolate and only type V is desired in a chocolate bar. To achieve type V crystals, tempering has to be done. Tempering of the chocolate allows the finished product to have a nice gloss, snap and taste. It also prevents “fat blooming” – where cocoa butter fats re-solidify, causing a gray-ish film to form on the product.

Ice cream

Besides the Chocolate Chantilly, we also had a go at making our own Ribena Sorbet! This is even simpler than the chantilly, all we had to do was pour the ribena juice into a bowl, add a few tablespoonfuls of food grade (!!) dry ice and just keep stirring until all the dry ice sublimes.

The making of ice cream/sorbet is actually a thermodynamic process of releasing heat energy from food. Dry ice is added to cool the liquid down rapidly by allowing the heat energy to be transferred over to itself, causing it to sublime into gas. As the liquid cools, the molecules in the liquid start to re-arrange themselves into orderly positions, leading to the formation of solids. Stirring of the liquid is important for a uniform suspension and to ensure that no large chunks of ice crystals are formed.

This was our group’s final product and it honestly tasted really good!! I was very tempted to make sorbet on my own at home after this but Ziquan said that they only sold the food grade dry ice in 5kg packs 🙁 don’t think I will ever need 5kg of dry ice… LOL

Moving on to what I’ve learnt from the readings about ice cream:

  • Ice cream is a complex and multi-phase emulsion since it consists of fats dispersed in water in 2 different phases – solid and liquid.
  • The 5 basic ingredients of ice cream are: ice, fats, sweetener, air and other solids.
  • Ice crystals are formed when water freezes at temperatures below its melting point. Ice crystals make up the body of the ice cream, giving it its structure. However, the size of the ice crystals formed is crucial as it determines how smooth the ice cream will be. Smaller ice crystal sizes are preferred since large ice crystals gives the ice cream a grainy mouthfeel.
  • Fats are typically obtained by using milk or cream. Apart from imparting richness and flavor to the ice cream, fats also improves the texture of the ice cream since higher proportion of fats means less proportion of water and that decreases the chance of formation of large ice crystals. However, a very high proportion of fats in ice cream is also not desirable because the resultant ice cream would taste less refreshing to us. This is because the thermal capacity of water is much larger than for fats and water has a greater ability to draw heat away from our tongue, giving us the cold and refreshing sensation.
  • Sweeteners are used not only to impart sweetness to the ice cream, but also helps in modifying the ice cream’s texture.  When sweeteners are added, the freezing point decreases and this ensures that the ice cream does not freeze solid. If no sweetener is added, the ice cream mix would freeze into a rock hard solid and it would be difficult to scrape. If too much of it was added, the mix would not sufficiently freeze and would still exist as a liquid.
  • Air helps to build volume in the ice cream, altering its texture. The word “over-run” is used to describe how much air is incorporated into the ice cream and ice cream with higher over-run is more airy and has less content per unit volume.
  • Other solids that could be added includes proteins, mineral salts or toppings. Addition of other solids may prevent formation of large ice crystals but would also affect the texture of the ice cream.
  • The creation of a good tub of ice cream all boils down to balance between the different components found in the mix.

After the readings for this chapter, I realised how I’ve always taken a bar of chocolate or a bowl of ice cream for granted. I’ve never really thought about the science behind it but with all these new knowledge, I think that I’ll be able to better appreciate the effort behind the chocolate/ ice cream that I consume.

That is all for this chapter, thank you for reading!