Formation of α-terpineol in citrus juices, model and buffer solutions

The formation of α-terpineol from its putative precursors in citrus juice (d-limonene and linalool) was investigated in juice, buffers and model solutions, α-Terpineol content was higher in commercial lemon juice than in orange or grapefruit juices. Its content exceeded its taste threshold of 2.5 mg/L in orange juice stored for 1 month at 35 °C. During storage of homogenized model solutions fortified with d-limonene or linalool, α-terpineol was simultaneously formed and degraded, especially at 45 °C and its formation was strongly dependent on pH. Linalool was a more reactive substrate than limonene for α-terpineol formation; the protonation in linalool was faster than in limonene. However, since there was more limonene than linalool in citrus juices, α-terpineol appeared to have been formed to about the same extent from both precursors.