A research team at the Leibniz Institute for Food Systems Biology at the Technical University of Munich has discovered the source of a previously undiscovered clove-like off-flavor in orange juice. This study demonstrates for the first time that the odor is caused by the odorant 5-vinylguaiacol. The findings suggest that this substance is produced primarily during the pasteurization process, when detergent residues react with natural orange juice components under the influence of heat.
This isn't the first time the orange juice industry has struggled with clove odor. Until now, 4-vinylguaiacol has been thought to be the main cause of this undesirable flavor, and is found in particularly high concentrations in long-term storage of orange juice. Therefore, quantitative detection of this odorant has long been part of routine quality control.
Eva Bauersachs, a doctoral student at the Freising Leibniz Institute and first author of the study, explains: "Recently, we received reports of some orange juice samples that, despite low concentrations of 4-vinylguaiacol, still had a distinct clove smell. We therefore asked ourselves what other odorants could be responsible for this undesirable off-flavor."
To investigate this question, a research team led by Martin Steinhaus, head of the Food Metabolome Chemistry research group at the Leibniz Institute, carried out extensive research in collaboration with Professor of Functional Plant Metabolomics and Chair of Food Chemistry and Molecular Sensory Science at the Technical University of Munich. The aim of the research was to identify the odorous substances responsible for previously unexplained odors and elucidate their origins.
Using techniques such as gas chromatography-olfactometry and aroma extract dilution analysis, the research team determined that the source of the odor in orange juice with a distinct clove smell was the odorant substance 5-vinylguaiacol. The presence of this substance in orange juice was previously unknown. Compared to 4-vinylguaiacol, 5-vinylguaiacol was even shown to have stronger odor activity in six commercially available orange juices with a clove off-flavor.
Further research showed that 5-vinylguaiacol is a unique component of hesperidin in orange juice that interacts with the process during pasteurization.
Lead researcher Martin Steinhaus said: "Insufficient machine rinsing after the CIP process could therefore lead to contamination of orange juice with peracetic acid and the formation of 5-vinylguaiacol during further processing. In light of this new scientific finding, the research team recommends that orange juice processing companies no longer use peracetic acid as a cleaning agent."
Compiled source: ScitechDaily