The study, published in the Journal of Agricultural and Food Chemistry, indicates that the guanosine derivatives and MSG may work together on umami receptors, boosting the overall sense of taste.
To scientists, umami is the taste of many different amino acids, or the building blocks of protein. But to a consumer, umami has been shown to contribute a full-bodied taste to products, as well as a distinctive aroma and mouthfeel.
Although umami taste receptors were only confirmed six years ago by researchers at the University of Miami School of Medicine, from a culinary perspective the umami taste is not new. Fermented fish sauces and intense meat and vegetable extracts have been valued in world cuisines for more than 2000 years.
According to Jacqueline Marcus, Food and Nutrition Consultant at Jacqueline B. Marcus & Associates, this inexplicable taste sensation can highlight sweetness, lessen bitterness and counterbalance saltiness. Indeed, proper use of the taste could even contribute to a 50 per cent salt reduction without compromising consumer acceptance, she said.
Glutamic acid and monosodium glutamate (MSG) are often used as an umami taste activator.
Previously, studies have shown that inosine 5'-monophosphate disodium salt (1a, IMP) and guanosine 5'-phosphate (GMP) can enhance the taste of glutamate.
"Systematic sensory studies on this synergism revealed that the umami intensity of aqueous solutions of MSG increased exponentially when IMP (or GMP) was added even in very low concentrations," explained lead author Paola Cairoli from the Universita degli Studi di Milano.
"This fact is of great relevance for the food industry, which uses ternary varying mixtures of MSG plus IMP plus GMP to enhance the flavour and mouthfulness of culinary products, snacks, soups, sauces, and seasonings," he added.
The new research investigated the potential of N2-alkyl and N2-acyl derivatives of GMP to synergistically interact with MSG.
Cairoli and co-workers report that all of the derivatives tested enhanced MSG more than IMP, with enhancements ranging from 1.2 to 5.7 (IMP was set at 1.0).
They report that the enhancing capabilities of the GMP derivatives were related to the chemical structure of the derivative.
"The synergistic activity of N2-substituted guanylic acids is related to the chain length of the alkyl or acyl substituent," stated the researchers.
"In both of these series such activity reaches a maximum, i.e., about six times the activity of IMP."
Taste in a general 'sense'
Previous research into taste has revealed that the human tongue has about 10,000 taste buds with five taste sensations: sweet, bitter, and umami, which work with a signal through a G-protein coupled receptor; salty and sour which work with ion channels.
Contrary to popular understanding, taste is not experienced on different parts of the tongue. Though there are small differences in sensation, which can be measured with highly specific instruments, all taste buds, essentially clusters of 50 to 100 cells, can respond to all types of taste.
Taste buds (or lingual papillae) are small structures on the upper surface of the tongue that provide information about the taste of food being eaten.
Source: Journal of Agricultural and Food Chemistry
Volume 56, Issue 3, Pages 1043-1050, doi: 10.1021/jf072803c
"Studies on Umami Taste. Synthesis of New Guanosine 5'-Phosphate Derivatives and Their Synergistic Effect with Monosodium Glutamate"
Authors: Paola Cairoli, S. Pieraccini, M. Sironi, C.F. Morelli, G. Speranza, P. Manitto