Smelling the fat: Odours are the first signal to levels of dietary fat, say Monell researchers
The suggestions come from sensory experts at the US-based Monell Center who recently published research demonstrating that we can reliably assess the fat content of foods based on their smell. Writing in PLoS One, the team noted that there is a vast amount of evidence to show that food smells are almost always detected before taste, and that their new data shows that fat is no different.
"In a series of three sequential experiments, using study populations from different cultures, we demonstrated that individuals are able to reliably detect fat content of food via odours alone," wrote the Monell team. "Over all three experiments, results clearly demonstrated that humans were able to detect minute differences between milk samples with varying grades of fat, even when embedded within a milk odour."
Led by Dr Sanne Boesveldt, the authors said their findings suggest there may be opportunities for the food industry to use innovative methods of adding fat odours to low-fat foods, thus making them more palatable - something that could aid public health efforts to reduce dietary fat intake.
Boesveldt added that the challenge now is to identify the odour molecules that allow people to detect and differentiate levels of fat.
"Fat molecules typically are not airborne, meaning that they are unlikely to be sensed by sniffing food samples," she said. "We will need sophisticated chemical analyses to sniff out the signal."
Study details
The Monell team investigated whether people could detect and differentiate the amount of fat in milk, commonly consumed globally. To achieve this, they asked healthy subjects to smell milk containing an amount of fat that might be encountered in a typical milk product: Either 0.125%, 1.4% or 2.7% fat.
Milk samples were presented to blindfolded subjects in three vials; two of the vials contained milk with the same percentage of fat, while the third contained milk with a different fat concentration. The task in all three tests was to smell the three vials and identify which of the samples was different.
The same experiment was conducted three times using different sets of participants of different cultures and weights. The first used healthy normal-weight people from the Philadelphia area, while the second experiment repeated the first study in a different cultural setting, the Wageningen area of the Netherlands. The third study, also conducted in Philadelphia, examined olfactory fat detection both in normal-weight and overweight subjects.
In all three experiments, the team found that participants could use their sense of smell to discriminate different levels of fat in the milk. This ability did not differ in the two cultures tested, even though people in the Netherlands on average consume more milk than Americans.
They also found no relationship between weight status and the ability to discriminate fat.
Senior author Johan Lundström, PhD, cognitive neuroscientist at Monell, commented that the results show that the human sense of smell "is far better at guiding us through our everyday lives than we give it credit for."
"That we have the ability to detect and discriminate minute differences in the fat content of our food suggests that this ability must have had considerable evolutionary importance," he added.
"Our findings that humans can detect the fat content of food via odours may open up new and innovative future paths towards a general reduction in our fat intake, and future studies should focus on determining the components in milk responsible for this effect," the team concluded.
Source: PloS One
Published online ahead of print, doi: 10.1371/journal.pone.0085977
"Detecting Fat Content of Food from a Distance: Olfactory-Based Fat Discrimination in Humans"
Authors: Sanne Boesveldt, Johan N. Lundström
