Research ushers in new era of boutique chocolate
A team of Belgian researchers has shown that the yeasts used to ferment cocoa during chocolate production can modify the aroma of the resulting chocolate. “This makes it possible to create a whole range of boutique chocolates to match everyone’s favourite flavour, similar to wines, tea, and coffee,” says Jan Steensels, a postdoctoral researcher at the University of Leuven, and the Flanders Institute for Biotechnology, Belgium. The research is published November 20 in Applied and Environmental Microbiology, a publication of the American Society for Microbiology.
Initially, the researchers sought robust yeast strains that could outcompete the many invading yeast strains that flood the cocoa beans during fermentation. “After harvesting, the cocoa beans are collected in large plastic boxes, or even piled in large heaps on the soil, right in the farms where they are grown,” explained Esther Meersman, a postdoctoral researcher with Steensels at the two institutions. The beans are surrounded by a gooey pulp, which is fermented by yeasts and bacteria. Any species in the environment can get into the mix, leaving little control over the ultimate flavour. But by outcompeting other microbes, robust yeast strains could prevent such infelicitous variability in taste, she said.
But the investigators noted striking differences in aroma among the chocolates made from fermentations using different robust yeasts, said Steensels. That was remarkable, he said, since only the yeast strains were different: the fermentations were performed identically, and the same recipe was used each time.
The team set out to breed novel yeast hybrids that would combine robustness with strong flavour production. “We were initially surprised that the volatile flavour compounds are retained in the beans during drying and roasting,” said Meersman. The researchers hypothesize that the volatiles are protected from evaporation since they are dissolved in the fat fraction.
The investigators, who collaborated in this research with Barry Callebaut, the world’s largest chocolate producer, have combined two critical characteristics of yeast in single hybrid variants: the ability to dominate cocoa fermentations, and to produce a specific flavour. “This means that for the first time, chocolate makers have a broad portfolio of different yeast strains that are all producing different flavours,” says Steensels. “This is similar to the current situation in beer brewing and wine making.” A new era of chocolate may be dawning.
American Society for Microbiology
Food odors activate impulse area of the brain in obese children
The area of the brain associated with impulsivity and the development of obsessive-compulsive disorder is activated in obese children when introduced to food smells, according to a study presented at the annual meeting of the Radiological Society of North America (RSNA).
"In order to fight obesity, it is crucial to understand the brain mechanisms of odor stimulus," said Pilar Dies-Suarez, M.D., chief radiologist at the Hospital Infantil de México Federico Gómez. "This study has given us a better understanding that obesity has a neurological disorder component, and the findings have the potential to affect treatment of obese patients."
In the United States, nearly 12.7 million children are obese, according to the Centers for Disease Control and Prevention (CDC). These children are at a higher risk to develop high blood pressure, type 2 diabetes, and breathing and joint problems, among many other health issues. They are also more likely to become obese adults.
The researchers studied 30 children between the ages of 6 and 10 years old. Half of the children had a normal body mass index (BMI) between 19 and 24, and the other half exhibited a BMI over 30, which is classified as obese. Each child was presented with three odor samples: chocolate, onion and a neutral odor of diluted acetone. As the participants smelled the samples, two MRI techniques—functional MRI (fMRI) and functional connectivity MRI (fcMRI)—were used to measure brain activity.
An evaluation of the fMRI results showed that in the obese children, the food odors triggered activation in the areas of the brain associated with impulse and the development of obsessive-compulsive disorder, while the areas of the brain associated with impulse control exhibited no activity. However, in the children with a normal BMI, the areas of the brain associated with pleasure regulation, organization and planning, as well as regions governing emotional processing or memory function, became more active.
In addition, the fcMRI results showed that when the normal-weight children smelled the onion, there was a connection between the gustatory cortex, which processes taste, and the area of the brain linked to reward anticipation. This connection did not occur in the obese children.
The chocolate smell elicited significant brain connections in obese children, compared to the normal-weight children.
"If we are able to identify the mechanisms that cause obesity, we will be able to change the way we treat these patients, and in turn, reduce obesity prevalence and save lives," Dr. Dies-Suarez said.
Co-authors on this study were Silva Hidalgo-Tobon, Ph.D., Benito De Celis IV, Eduardo Barragan, Eduardo Castro, M.D., Samuel Flores, M.D., Porfírio Ibanez and Manuel Obregon.
Radiological Society of North America