Over the years. chocolate has become a favourite high-sugar treat. — PIXABAY/Pexels
For various reasons, I am currently staying in the UK and visiting London a lot. And while in an Austrian deli in London, I had a rather insipid Sacher-torte, the famous chocolate cake invented in 1832 for important dinner guests of the then Austrian State Chancellor, Prince Wenzel von Metternich.
The apprentice chef who invented the cake was 16-year-old Franz Sacher, who had to take over the culinary duties that evening due to the sudden illness of the main chef. Sacher was plainly informed by Metternich: “I hope you won’t disgrace me tonight.”
So, not too much pressure on the teenager then.
But Sacher took his chance and conjured up the confection of his lifetime, a chocolate cake so sumptuous people often salivate on hearing of a Sacher-torte nearby. I have been to Salzburg to buy one at the Sacher Hotel and it was indeed an almost overpowering feast of chocolate. And the memory of that cake came flooding back in London when I was eating a poor substitute.
And so, you now know this column today is about chocolate, but it is far from the usual gushy fawning over delicious chocolates. In fact, it starts with a warning.
Carbonyls
Under roasting heat when preparing cocoa, new molecules like unsaturated carbonyls are formed from reactions of various ingredients in cocoa beans under high temperatures. This class of carbonyls is highly reactive and potentially genotoxic (able to cause damage to human DNA) when ingested.
The quantity of furan-2(5H)-one appears to be significantly increased during the commercial or home baking of chocolate. This can cause damage to human DNA when ingested. —POLINA TANKILEVITCH/Pexels
The most notable carbonyl is furan-2(5H)-one, a buttery-tasting compound banned by the EU from use as a food additive. Curiously, the quantity of furan-2(5H)-one appears to be significantly increased during the commercial or home baking of chocolate, rising to as much as 4.3 milligrams per kilo. This is substantially above the EU limit of only 0.15 milligrams per person per day, so a large chunk of a baked chocolate cake would easily exceed the EU recommended threshold.
On the other hand, there is scant information about the effect of such amounts of furan-2(5H)-one on humans, so it may not be as genotoxic as assumed, or it possibly might be worse. We simply do not know at present.
Oral tribology
Most people would have noticed that there is something much more about chocolate than just taste. It may be because chocolate is one of those rare Edible Phase Change Materials (EPCM), a class of interesting foods that conveys a sensation of “food melting in the mouth”.
This is a very desirable “mouth feel” experience that most people enjoy when eating. This phase change occurs in a sequence of dynamic interactions between the ingested EPCM and oral surfaces in the mouth. It may start from a licking stage by the tongue to a saliva-mixed state as other glands get involved. There are therefore several levels of contact in the mouth, ranging from primary tastebud activations on the tongue, lubrication effects due to salivary interactions spreading across the tongue, to an overall macro (higher-level) reaction as the ECPM changes from its initial presented state to becoming an emulsified liquid in the mouth.
This emulsification process can intensify the ECPM’s coefficient of contact friction with sensory cells by three times – this means that the sensation of the EPCM’s taste and flavour is stronger by three times as the emulsified ECPM covers and becomes more deeply distributed around the tastebuds and olfactory receptors.
Note that most foods also get affected and processed by saliva and chewing, but that is the result of mastication, rather than a phase change of the food item itself.
The overall subject is called “oral tribology”, which is the study of friction, lubrication, and wear processes that occur in the mouth during food consumption and oral processing. This is an interesting area as oral tribology is heavily involved in:
• Food product development
• Texture and mouthfeel optimization
• Understanding the sensory perception of foods
• Developing food alternatives
There is specialised equipment used for studying oral tribology, such as:
• Friction and flow testing devices
• Oral processing simulators
• Other tribological instruments designed for food testing
However, there is a complex and profound analysis needed to bridge the gap between physical measurements and human sensory perception of foods during ingestion. Tribological scientific equipment may be able to define ECPMs, but humans must always be involved in specifying whether any ECPM is actually enjoyable to eat.
Sugar. Oops.
A recent study published in health-conscious Germany had a classic “good news, bad news” conclusion. The good news is that free sugar consumption amongst young children in Germany has been falling for the last few years. The bad news is that current levels of free sugar consumption are still significantly above the World Health Organisation (WHO)’s rather generous guidelines of 10% of daily calories per day. At current trends, it will be quite a few more years before German youngsters meet the WHO guidelines.
Chocolate is one of those rare foods that convey a sense of melting in the mouth. — ANETE LUSINA/Pexels
At this point, one should be aware that 10% of daily calories from free sugar is a rather lousy target health-wise. This is equivalent to 50 grams of sugar a day for someone on 2,000 calories. Therefore, eating fruits or other natural sugars would easily breach 50 grams of sugar consumption per day for many people.
10% of daily calories from free sugar is a huge amount for the body to process and metabolise and is probably an underlying factor behind the ongoing global pandemic of metabolic syndrome, affecting approximately 1.4 billion people on Earth.
The WHO defines “free sugar” as any form of sugar, including honey, syrup, and fruit juice concentrates, added by a manufacturer or when preparing food and beverages at home. Free sugar also includes the vestigal sugar in pressed or processed juices but does not count sugars from fresh fruits such as mangos, papayas, oranges, etc.
The WHO limit for daily free sugar intake is disappointing, because less than 10 years ago, in 2015, the WHO was advocating for a daily free sugar limit of just 25 grams a day. Whatever changed between then and now is unclear, but the powerful food and sugar lobby probably had something to do with such a huge, unhealthy upward revision in the permitted free sugar levels for humans.
Now, the WHO merely and rather lamely “suggests” cutting down free sugar consumption to 5% or less of daily calories.
A chocolatey trick
To be fair, many people are now aware of the perils of eating too much free sugar, but many “sugar-free” foods either do not taste as good or contain artificial sugar substitutes which have been claimed to cause other damaging effects, such as dysfunction of the human gut microbiome, inflammation of various organs in the body (particularly the liver), and potentially increase the risk of cancers.
However, a little trick in the kitchen when baking chocolate goods may help reduce the usual amount of sugar needed, plus offer a small metabolic benefit in terms of slightly lowering the Glycaemic Index (i.e., causing slower processing of glucose from food).
A paper from late last year by an American university explored the use of fine, insoluble starch granules to replace sugar when baking chocolate cakes. The starch granules tested were rice flour and oat flour.
The experiment was simple. Sixty-six subjects were made to taste various cakes made with varying proportions of sugar and the test flours. The tasting was done wearing a peg on the nose and then without a peg on the nose to ascertain the impact on the olfactory nerves. Regardless, the test subjects generally did not much like the chocolate cakes made with rice flour, but they liked the cakes made using oat flour.
Overall, the experiment found that people enjoyed most the chocolate cakes made by replacing 25% of the normal sugar with oat flour, with some subjects even preferring this reduced sugar mix to the original full-sugar cakes. The 25% oat flour replacement cakes were often described as “creamier”.
Free sugar is any form of sugar, including honey, syrup and sugar concentrates added to food and beverages. The WHO recommendation is to limit it to 50 grams a day. — PIXABAY/Pexels
Whether this use of oat flour would also transfer to non-chocolate-based cakes is unclear as the research did not cover this (and I am not at home to test this out). But it is plausible that it might also work for non-chocolate cakes, in which case it would be an ideal way to cut down 25% of the sugar in all cakes.
Sharing chocolate
A curious statistic indicates that over 90% of Americans prefer to share chocolate and candies for Valentine’s Day. It would seem chocolate is an enduring symbol of love and affection there. It may be because people really want their loved ones to associate this ECPM with them.
It is understandable because good chocolate is one of the few highly sensual and delicious things that can always be enjoyed with one’s clothes on.
The views expressed here are entirely the writer’s own.
