2-Methyl-3-furanthiol and Methional Are Possible Off-flavors in Stored Orange Juice: Aroma-similarity, NIF/SNIF GC-O, and GC Analyses

The occurrence of methional in fresh orange juice, and possible occurrence of beta-damascenone in heated orange juice, has been previously suggested. Here we report on the occurrence of 2-methyl-3-furanthiol in the headspace, collected by solid-phase micro-extraction, of fresh, pasteurized, and stored orange juice. The contents of 2-methyl-3-furanthiol and methional were quantified, and the relative level of beta-damascenone was estimated, in the headspace of fresh, pasteurized, and stored orange juices using the nasal impact frequency (NIF) and surface of NIF (SNIF) GC-Olfactometry procedure. 2-Methyl-3-furanthiol concentrations were 2 ng/L in fresh and pasteurized Shamuti orange juice, and 270 ng/L in stored juice of the same variety. Methional concentrations were 550, 830, and 11,550 ng/L in fresh, pasteurized, and stored pasteurized juices, respectively. beta-Damascenone content appeared to have increased during pasteurization and storage. Aroma-similarity experiments strongly suggest that 2-methyl-3-furanthiol and methional, at the levels found in stored orange juice (21 days at 35 degrees C), contribute to stored orange juice off-flavor.