Submitted to: Journal of Sensory Studies
Publication Type: Peer reviewed journal
Publication Acceptance Date: 6/12/2013
Publication Date: 6/12/2013
Citation: Dea, S., Plotto, A., Manthey, J.A., Raithore, S., Irey, M., Baldwin, E.A. 2013. Interactions and thresholds of limonin and nomilin in bitterness perception in orange juice and other matrices. Journal of Sensory Studies. 28:311-323. Interpretive Summary: Limonin and nomilin are two bitter compounds in orange juice. If they are present in too high an amount, such as in juice from oranges infected with Huanglongbing (greening disease), they can impart a bitter taste. This is the first study that measures the threshold (concentration level necessary to impart bitter taste) of both compounds in orange juice and their interaction with each other.
Technical Abstract: Limonin and nomilin are two bitter compounds present in citrus and are thought to cause the bitter off-flavor of Huanglongbing-infected fruit/juice. This study determined the thresholds of limonin, nomilin, and their combination in a simple matrix (sucrose and citric acid), a complex matrix (sucrose, glucose, fructose, citric and malic acid at levels found in orange juice), and in orange juice. In addition, the effect of sugar and acid levels in orange juice on the bitterness perception of limonin and nomilin was investigated. In the simple matrix, the threshold of limonin was lower than nomilin, and when the compounds were added in combination at an equal ratio, their individual thresholds decreased significantly. Similarly, the presence of nomilin at a fixed concentration (2 mg/L), decreased the threshold of limonin compared to limonin alone in the simple matrix. The effect was not as significant for nomilin when limonin concentration was maintained at a constant level. Thresholds of limonin and nomilin were lower in orange juice than in the complex matrix. Increasing levels of sucrose or citric acid decreased the perception of bitterness induced by limonin and nomilin in orange juice, with addition of sucrose being slightly more effective than addition of citric acid.