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

The formation of alpha-terpineol from its putative precursors in citrus jui ce (d-limonene and linalool) was investigated in juice, buffers and model s olutions, alpha-Terpineol content was higher in commercial lemon juice than in orange or grapefruit juices. its content exceeded its taste threshold o f 2.5 mg/L in orange juice stored for 1 month at 35 degrees C. During stora ge of homogenized model solutions fortified with d-limonene or linalool, al pha-terpineol was simultaneously formed and degraded, especially at 45 degr ees C and its formation was strongly dependent on pH. Linalool was a more r eactive substrate than limonene for alpha-terpineol formation; the protonat ion in linalool was faster than in limonene. However, since there was more limonene than linalool in citrus juices, alpha-terpineol appeared to have b een formed to about the same extent from both precursors.