Orange juice: pure or touched? Image: Elhuyar Fundazioa
Read out Each fruit juice has its characteristic fingerprint, where it is easy to identify the blend of high-quality fruit juices with cheaper juices. A unique feature is the composition of phenols. These are aromatic compounds that are found in many different species in each plant. Of the 16 Spanish varieties of fruit studied, no two have the same composition of these substances, scientists from the University of the Basque Country found. Not only the type of phenols differs from plant to plant, also the amount contained is different for each type. The research team therefore examined 16 types of fruit and a total of 77 subspecies in a mass spectrometer and high-performance liquid chromatography (HPLC) to determine both phenol types and their abundance for each fruit. The amount of combination options alone was enough to give each fruit a unique fingerprint, the researchers found.

In practical tests, the scientists were able to clearly identify, for example, a blend of orange juice with grapefruit or lemon juice with the help of the fingerprints of the fruit. However, in distinguishing tangerine and orange juice, the method failed. The problem is the way statistical data are evaluated: Since there are thousands of different types of phenols, the research team used fingerprints to pin down some sections in the phenolic profiles where the differences were greatest.

However, the relationship between tangerines and oranges is so narrow that only looking at these striking sections is not enough to distinguish them. For this reason, the chemists want to further refine the fingerprints in a next step in order to be able to extend their investigations of pure fruit juices to commercial juice products and to transfer any panschers here as well.

Luis Angel Berrueta (Institute of Analytical Chemistry of the University of the Basque Country, Bilbao): Press release from the University of the Basque Country ddp / science.de? Livia Rasche advertisement

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