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Title: Threshold values for off flavor compounds in a deodorized orange juice (pumpout) matrix

Author
item Plotto, Anne
item Goodner, Kevin
item Narciso, Jan
item Baldwin, Elizabeth - Liz

Submitted to: Subtropical Technology Conference Proceedings
Publication Type: Abstract Only
Publication Acceptance Date: 9/11/2006
Publication Date: 10/18/2006
Citation: Plotto, A., Goodner, K.L., Narciso, J.A., Baldwin, E.A. 2006. Threshold values for off flavor compounds in a deodorized orange juice (pumpout) matrix. Subtropical Technology Conference Proceedings. 57:6-7.

Interpretive Summary:

Technical Abstract: The data presented is part of a continuing study to provide the industry with threshold guidelines more adequate for use of flavors in citrus juices. The Best Estimate Threshold (BET) of volatile compounds reported to generate off-flavor in orange juice (OJ) was determined in a deodorized OJ matrix (pumpout). The Three-Alternative-Forced-Choice (3-AFC) method was used (ASTM: E-679). The USDA staff, comprised of 16 to 20 experienced panelists, age 25 to 65, were presented with orange juice samples (15 ml in 30 ml capped cups) arranged in five rows of three samples corresponding to five spiking levels, each separated by a factor of 3, with a 3-AFC presentation at each level. For each compound, the test was repeated four times, adjusting for concentrations when necessary. The orange juice matrix was sampled several times during the study to verify absence of microorganisms that might induce off-flavor. Compounds with the lowest population BET were 2-methyl-3-furanthiol, 1,4-cineole, and guaiacol, with orthonasal BET of 0.64, 2.69, and 3.64 mg/L, respectively. 2-Methyl-3-furanthiol, as well as methional, furaneol, p-vinylphenol, and ethanol, are likely to be perceived as off flavors in some juices, since their thresholds could be lower than reported concentrations if the juice was thermally abused, or tainted with bacterial contamination. Other compounds, such as terpiene-4-ol and a-terpineol, which are reported off flavors, had thresholds significantly higher than reported concentrations, and, therefore, would not impart an off-favor to orange juice. Interactions between off flavor compounds with orange juice desirable flavor volatiles will be studied by analyzing the perception of fresh orange juice spiked with these compounds at subthreshold levels.