Science’s Search For Secret Of Heat Resistant Chocolate

Why God!? Why!?

Science, it seeks to solve some of the biggest problems facing humanity. It tries to understand the nature of life, cure cancer and save the planet. However, now it seems to be dealing with THE big issue facing society, increasing the melting point of chocolate!

We’ve all been there, you hold a toffee crisp (or whatever happens to be your weapon of choice) for too long and you are left with horrible chocolatey sticky fingers. Well never fear, wipe away those tears…and the melted chocolate…because science is working on it! A new paper from the University of  Guelph, Canada, has reviewed many potential techniques for increasing the melting point of chocolate and have outlined 3 concepts:

  • Enhancing the microstructure of the materials
  • Addition of a polymer
  • Increasing the melting point of the fat phase.

But, how would you go about doing each…

Microstructure Enhancement

Photograph and full spectrum autofluorescence micrograph of chocolate confection showing (A) cream filling, (B) milk chocolate coating, (C) white chocolate coating.

One technique mentioned to do this was to add water. However, it’s not quite as simple as it sounds. There are several suggested complicated ways of incorporating the water. You could add it directly with the ‘Lataner’ technique  (4-20% water) ensuring that all the sugar is disolved. This will produce chocolate that “is said to be able to withstand any climatic conditions found in any part of the world”. However, it is also highly viscosous making it difficult to mould and not commercially viable.

The ‘Russell and Zenlea’  method is more complicated still, involving warm water addition with the chocolate being “stirred continuously in a steam jacketed mixer until a homogenous”. This produces chocolate that can withstand up to approximately 49 °C.

There are several other ways to directly add water to chocolate. However, they all have two major drawback, a susceptibiltiy to sugar bloom (what you see when the chocolate gets a weird white gray coat) and a reduction in the quality of the chocolate.

You can also add water indirectly. Frieman in 1921 as well as Kempf & Downey both produced high melting-point chocolate (HMC) this way. However, “chocolate likely had a high viscosity, poor texture and an unfinished flavor”. Other methods of water inclusion involved the use of water/fat emulsion. These prototypes produces chocolate able to withstand sufficient temperatures. But, there was a lack of taste testing of the products.

So, whilst overall these methods were are able to increase the melting point the quality was sacrificed. Clearly not an ideal situation.

Oil/fat binding polymer

This method of altering chocolate really came into its own in 2006 when Ogunwolu and Jayeola looked at adding cornstarch or gelatin. They were added at levels of 2.5, 5.0, 7.5, or 10.0% to other chocolate ingredients at the grinding and mixing stage. They then looked at the melting points and found that both caused it to increase (Figure 1)

Figure 1: Melting points of chocolate with addition of cornstarch or gelatin

These forms of chocolate also, like the previously mentioned methods, had their drawbacks. Sensory evaluation showed that 10% cornstarch chocolate whilst not significantly different than conventional milk chocolate in colour, taste and  smoothness, there was a significant decrease in sweetness of the product (ρ < 0.05). 10% gelatin chocolate was observed to not be significantly different in colour and sweetness, although did have significantly poorer taste and decreased smoothness when compared to conventional milk chocolate.

Not only are there taste issues with the products some countries do not permit any amount of oat flour, cornstarch or gelatin to be present in chocolate, limiting the potential applications of these methods.

High fat melting point addition

Several different high melting point fats have been tested as a component of chocolate. Two that have had the most research conducted into them are mahua (Madhuca latifolia) and kokum (Garcinia indica). These are both found in trees in India. The blending of these fats fats, was observed to improve the solidification and melting characteristics of the product. However, there would need to be a compromise reached between heat resistance and taste. A sensory evaluation found that 5% kokum chocolate was not significantly worse than normal chocolate, although this low level of the fat only raises the melting point to 34.8 °C. Also, there was no data for the taste of kokum chocolate at greater than 5%.

Heat resistant chocolate has been an idea that people have tried to perfect for a long time. During WW2 the American Military tried to make a Hershey Field Ration “D” with oat flower. As the above research shows it is possible to make heat resistant chocolate. However, the products currently are neither simple, inexpensive nor of sufficient quality compared to regular chocolate. So, nice try science…but you’ve still got a way to go!

Terri A. Stortz & Alejandro G. Marangoni (2011). Heat resistant chocolate Trends in Food Science & Technology : 10.1016/j.tifs.2011.02.001

Maheshwari, B., & Yella Reddy, S. (2005). Application of kokum (Garcinia indica) fat as cocoa butter improver in chocolate Journal of the Science of Food and Agriculture, 85 (1), 135-140 DOI: 10.1002/jsfa.1967

Ogunwolu, S., & Jayeola, C. (2006). Development of non-conventional thermo-resistant chocolate for the tropics British Food Journal, 108 (6), 451-455 DOI: 10.1108/00070700610668423


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