Are genes the deciding factor in whether or not foods taste good to us? Will the food industry soon be able to use DNA banks to determine whether a new product will be well received by consumers? Students at the HLFS Ursprung investigated these questions using a human gene, which identifies the taste of bitterness on the tongue. They took DNA tests from over 400 subjects, who tasted and rated the bitter concentrations, as well as a number of stevia-sweetened foods, including a chokeberry drink, which they had previously developed.
There are 25 genes in humans that identify significant bitter tastes, of which the gene TAS2R38 is particularly well researched. The decoding of this gene shows that it can selectively vary on three positions and, therefore, has three SNPs (SNP = Single Nucleotide Polymorphism). Depending on which of these point mutations exist in the gene, the "construction" of the receptors on the tongue can change, and with it, the function with regard to the detection of bitterness. And this is actually what the students demonstrated: small variations in the genetic makeup cause large differences in the perception of taste. These changes can go so far that the slightest amount of a known bitter substance can sicken one
Of about 400 collected (and anonymous) DNA tests, the young researchers could successfully analyze 296 of them with the three SNPs in the school laboratory and correlate them to the tasting. As a result, they made an astonishing discovery: people who carry the so-called “PAV/PAV” variation of the gene do not perceive stevia as unpleasant; rather, they rate all tastings positively or at least as neutral. The main point is that PAV/PAV characterizes so-called human super-tasters, persons who can subtly perceive bitterness. The result of the students’ research therefore contradicted the established working hypothesis that people with gene type PAV/PAV would (rather) not like stevia. In the students’ small random sampling, the “stevia gene type” PAV/PAV was found seven percent of the time. However, according to scientific studies, up to 14 percent of Europeans have this gene type (see bibliography 3), and would therefore enjoy the taste of stevia. Statistically, the students’ finding is highly significant and 99 percent reliable.
The students decided to research stevia, because it is a current issue: the calorie-free sweetener from the stevia plant is expected to be approved by the EU in 2011. Food companies are ready to develop products with stevia. It is well known that many people will find stevia sweetener as metallic, medicinal, or bitter, that is, unpleasant tasting. The students wanted to understand this phenomenon on a micro-biological level.
In addition, the young scientists became interested in taste perception through the development of their own chokeberry drinks. According to earlier studies, aronia, which is the scientific name of the chokeberry, can promote one’s health and even prevent cancer (see bibliography 2). However, it can taste very bitter and astringent. According to the hypothesis, the gene TAS2R38 also plays a role in the perception of taste of the chokeberry. The statistical analysis of the collected data shows trends in taste that can be collated to the distinct genetic variations of TAS2R38 and are likewise statistically significant. However, further research on the makeup of the chokeberry and additional genes of taste would be necessary.
Last but not least, the students are also interested in the ethical aspects of stevia: when students use human DNA tests for information about taste perception, what facts can only be decoded in a professional laboratory, e.g. about illnesses or personal characteristics? Who makes sure that the sensitive data doesn’t fall into the wrong hands? Lawmakers can only try to catch up to the fast-paced field of genetic engineering. They must understand what needs to be regulated before writing laws that create bans or rules, especially when it comes to what experiments need to be controlled or prohibited. At a large exhibit in the House of Nature, where the data for the project was collected, the students made people aware of this problem and conducted interviews about “DNA Data Protection”.
House of Nature
Do it yourself
Genetic make-up, genotype
Analysis and Interpretation
Cappuccino powder or mix
1.) Kim UK, et al. 2003.
Positional cloning of the human quantitative trait locus underlying taste sensitivity to phenylthiocarbamide. Science. 299:1221–1225.
2.) Kokotkiewicz A, et al 2010
Aronia plants: a review of traditional use, biological activities, and perspectives for modern medicine.
J Med Food. 13(2):255-69.
3.) Sausenthaler S. et al 2009
Lack of Relation Between Bitter Taste Receptor TAS2R38 and BMI in Adults.
Obesity 17 5, 937-938