View online magazine
Researchers from the Monell Chemical Senses Center in Philadelphia, USA, have teamed up with scientists from Tokyo University of Agriculture to use novel molecular methods to identify chemical compounds from common foods that activate human bitter taste receptors. The findings provide a practical means to manipulate food flavour in general and bitter taste in particular.
"Identification of bitter taste compounds and their corresponding receptors opens doors to screening for specific bitter receptor inhibitors," said senior author Liquan Huang, a molecular biologist at Monell. "Such inhibitors can be used to suppress unpleasantness and thereby increase palatability and acceptance of health-promoting bitter foods, such as green vegetables or soy products."
While a little bitterness is often considered a desirable component of a food's flavour, extensive bitterness can limit food acceptance.
About 25 different human bitter receptors have been identified from human genome sequences. However, only a few of these are activated by known chemical compounds. The remainders are 'orphan receptors', meaning that the compounds that bind to and activate them have not been identified. Consequently, it is unclear how these orphan receptors contribute to bitter taste perception. Huang and his collaborators 'deorphanised' several bitter receptors by demonstrating that peptides from fermented foods can specifically stimulate human bitter taste receptors expressed in a cell culture system (Fig.1).
Fermented foods, such as cheese or miso, are characterised by bitter off-tastes. These foods also contain abundant quantities of peptides, which are short chains of amino acids, the building blocks of proteins.
The results reveal the molecular identities of chemical food components responsible for the bitterness of fermented foods and demonstrate that bitter-tasting peptides are detected by human bitter receptors in an analogous manner to other bitter compounds.
"Information on how food constituents interact with receptors is needed to design and identify inhibitors and enhancers that can be targeted towards specific bitter compounds," says Huang. "Our findings may help make health-promoting bitter foods such as broccoli more palatable for children and adults."
The findings are published in the journal Biochemical and Biophysical Research Communications.
Meanwhile, a new primer written by scientists at the Monell Center and Florida State University and published in the 26th February issue of Current Biology, provides a clear and accessible overview of recent advances in understanding human taste perception and its underlying biology.
Within the past few years, identification of receptors for sweet, bitter and umami (savory) taste has led to new insights regarding how taste functions, but many questions remain to be answered. The Current Biology primer reviews the current state of knowledge regarding how taste stimuli are detected and ultimately translated by the nervous system into the perceptual experiences of sweet, sour, salty, bitter, and umami.
Such perceptual evaluations are related to the function and ultimately, the consequences, of taste evaluation. These can range from pleasurable emotional reactions, for example the delight a child receives from a sweet candy, to the critical life-dependent response that causes a person to spit out a bitter potential toxin.
Author Paul A S Breslin, a sensory scientist at the Monell Center, explained: "For all mammals, the collective influence of taste over a lifetime has a huge impact on pleasure, health, well-being, and disease. Taste's importance to our daily lives is self-evident in its metaphors - for example: the 'sweetness' of welcoming a newborn child, the 'bitterness' of defeat, the 'souring' of a relationship, and describing a truly good human as the 'salt' of the earth."
Over time, consumers develop a set of cues that we then use to make inferences about products, such as 'all French restaurants have great service' or 'more expensive candles smell better'.
However, this set of predictable beliefs can make it difficult for people to learn and recognise other real, positive qualities that are indicated by the same cues, reveals a new study in the Journal of Consumer Research.
"Once people learned that a cue predicted an outcome, they became less likely to learn about this very same cue with respect to a different outcome," write Marcus Cunha Jr of the University of Washington, and Chris Janiszewski and Juliano Laran of the University of Florida. "The implication is that the learning system is designed to discourage single cue-multiple outcome learning."
In the pilot study of a series of five experiments, the researchers used cheese tasting to explore the development of predictive knowledge structures, a phenomenon also known as 'protection of prior learning'. They first had participants taste an orange rind Raclette cheese that was mild and creamy, and a purple rind Drunken Goat cheese that was much stronger tasting and dry. They then had participants rate the cheeses on a scale of mild to strong to induce the association with an orange rind and a mild flavoured cheese. A control group also tasted two different types of cheese but did not rate them.
To test whether an association between an orange rind and mild flavour would make it more difficult for consumers to gauge other existing qualities, such as texture, tasters were then asked to rate the creaminess of a mild, creamy Port Salut with an orange rind and a dry Manchego with no rind. Surprisingly, participants were less likely than the control group to expect the second orange rind cheese to be creamy, even though the first one had also been creamy.
INGREDIENTS ADDRESS HEALTH TRENDS
Mineral fortification is one of the top trends in the food industry and especially in functional food to address common deficiencies or specific health benefits with these essential nutrients.
Jungbunzlauer Special Salts comprise a range of high-purity, neutral tasting organic sources of calcium, magnesium and potassium derived from citric or gluconic acid. These organic mineral salts are supported by the health claims legislation world-wide, due to their effectiveness when used for fortification in human studies. On top of their high bioavailability, specific benefits such as heart health, bone health, muscle health and anti-obesity effect are exploited by the food and pharmaceutical industry for new healthy product concepts.
Sugar is proven to have an influence on obesity and overweight. However, it has a taste and sweetness profile which is not easy to mimic but preferred by consumers. Jungbunzlauer's sugar replacement Erythritol is a novel bulk sweetener which offers a taste profile very close to sugar and allows creating fully flavoured products at a lower calorie level. Erythritol is tooth friendly, offers a very low glycemic index, a high digestive tolerance and a great blendability with other sweeteners.
Cardiovascular illness is nowadays the most important group of disease in the civilised world. Salt and more particular sodium are major contributors to high blood pressure and increase heart disease and strokes. Salt, however, contributes strongly to the taste profile of food products. Jungbunzlauer's sub4salt allows a significant sodium reduction with a taste profile similar to sodium chloride and does not alter the functional aspects.
Jungbunzlauer is based in Basel, Switerland. www.jungbunzlauer.com.