chocolate. Nothing else pulls you into the fridge in the middle of the night or gives you cravings for random food quite like it, and it even has its own theme park. But what gives it that unmistakable flavor that humans obviously can’t get enough of?
For thousands of years, chocolate has been processed in much the same way. Something chocolate addicts and wine lovers know is that chocolate and wine can have a very different flavor depending on where it comes from. Chocolate can have fruity, nutty, earthy, smoky, and even floral undertones depending on where the beans are grown. Another thing on which the flavor of sweets and syrup depends is fermentation. Microbes are involved in this fermentation, creating the different flavors that keep us coming back for more.
If you suddenly find that this is unappetizing, it should not be. Food microbiologist Jian Zhao from the University of South Wales in Australia is now trying to use the science of chocolate to modernize production methods without sacrificing flavour. This can help chocolate manufacturers improve the consistency. Understanding the microbes behind irresistible flavors, something Zhao has also studied in brewing coffee beans and other foods, may make it possible to create chocolate like nothing you’ve tasted before. But first, the fermentation.
“Research has greatly improved our understanding of the roles of different microbes in cocoa bean fermentation, which is moving towards the development of starter microbial cultures,” Zhao told SYFY WIRE.
Have you ever tasted a raw cocoa bean? Bitterness is nowhere near a chocolate bar. Beans are rich in polyphenols, which are compounds like flavonoids that give them an astringent taste but also act as antioxidants. This explains where dark chocolate earned its superfood status. Fermentation removes the edge of the bitter cocoa beans, which are stored in boxes or stacked and covered with banana leaves, then left to decompose. Don’t lose your appetite yet. As the shell inside the cocoa beans is cracked, some of the chocolate’s most distinct flavors emerge.
Microbes remove the pulp from the bean, and more microbes – yeasts – convert their sugars into carbon dioxide and ethanol (unlike wine). Bacteria and yeasts have different methods of fermenting pulp that include aerobic and anaerobic phases. Yeast will devour the fructose, glucose, and sucrose in the pulp anaerobically, while bacteria use an aerobic process that breaks down the pulp and produces lactic and acetic acid that eat up the bean’s cell walls.
“The most important group of microbes for fermentation of cocoa beans are yeasts, which have an essential role in the development of chocolate flavor,” Zhao said.
When the enzymes in the proteins and carbohydrates in the pulp where it is digested by yeast break down, and the embryo in the beans dies, a chain reaction of chemical reactions kicks off and flavors begin to develop. They also take on a more chocolate color, which is a result of the pigment flavonoid anthocyanin. After processing, which includes fermentation and drying, the beans are shipped to the manufacturers and roasted. Eliminates the astringent smell that results from fermentation. Roasting also brings out hundreds of volatile flavor compounds (formed from flavor precursors that emerged during fermentation) that will tempt you to eat another bonbon.
Since the spontaneous processes that occur during fermentation can vary and make the flavor inconsistent, Zhao tries to figure out which microbes to cultivate.
“They will give us better control over the fermentation process and produce better quality cocoa beans,” he said.
The University of New South Wales food microbiology team, led by Zhao, is collaborating with a French company to test some yeast strains that were isolated from fermentation, and over which there was little control. Starter farms are already used in the production of wine and fermented foods such as coffee and soy sauce. Introducing them to chocolate production makes sense for a consistent texture and flavor.
Imagine tasting the most wrong piece of chocolate, truffles, bonbons or something else. It’s the microbes – not just the chocolate maker.