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

The formation of alpha-terpineol from its putative precursors in citrus juice (d-limonene and linalool) was investigated in juice, buffers and model solutions, alpha-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 degrees C. During storage of homogenized model solutions fortified with d-limonene or linalool, alpha-terpineol was simultaneously formed and degraded, especially at 45 degrees C and its formation was strongly dependent on pH. Linalool was a more reactive substrate than limonene for alpha-terpineol formation; the protonation in linalool was faster than in limonene. However, since there was more limonene than linalool in citrus juices, alpha-terpineol appeared to have been formed to about the same extent from both precursors.