Title: Effect of Liberibacter infection (Huanglongbing or "greening" disease) of citrus on orange juice flavor quality by sensory evaluation Authors
Submitted to: Journal of Food Science
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: January 31, 2010
Publication Date: May 28, 2010
Citation: Plotto, A., Baldwin, E., Mccollum, G., Manthey, J., Narciso, J., Irey, M. 2010. Effect of Liberibacter infection (Huanglongbing or "greening" disease) of citrus on orange juice flavor quality by sensory evaluation. Journal of Food Science. 75(4):S220-S230. Interpretive Summary: Huanglongbing (HLB) is an emerging disease that is affecting Florida citrus industry. Anecdotal reports mention that trees affected with the disease produce fruit that impart off-flavor to the juice. This study examines flavor differences between juice made with normal or fruit symptomatic for the disease from infected trees, and juice made with fruit from healthy trees, by sensory analysis. Rumors that juice made with oranges harvested from HLB affected trees is off-flavored appeared to be generally more true for Hamlin juice, especially for Hamlin juice made with fruit showing symptoms of the disease. For the other varieties, flavor differences between juice made with fruit harvested from HLB diseased and healthy trees varied greatly between trees, season, and even processing method. Under a commercial processing situation, where juice is blended from several varieties, seasons and multiple locations, it is expected that off-flavor will not be a major problem.
Technical Abstract: There have been some anecdotal reports that Liberibacter asiaticus [(+) Las] infection of citrus trees, recently introduced in Florida, imparts off flavor to orange juice. It is of interest to the industry to know how much Liberibacter infection affects juice quality with respect to variety, maturity or processing method. Hamlin, Midsweet and Valencia oranges were harvested over two years from healthy (-) Las or (+) Las affected trees and from different groves and included were normal looking fruit (non-symptomatic) from diseased trees and symptomatic fruit (small, green and lopsided). In the first year, fruit were manually juiced, while in the second year, a commercial process was used. Juice from (+) Las trees was compared to juice from healthy (- Las) trees in difference-from-control tests, and by descriptive analysis (included symptomatic and non-symptomatic fruit). Results showed large variability due to tree, harvest date, and variety. Juice from Hamlin (+) Las affected trees tended to be more bitter and sour than their control counterpart. On the other hand, (+) Las juice from Valencia trees that was hand processed was perceived to have some off flavor and bitterness compared to control, but the following year, commercially processed Valencia juice from (+) Las trees was perceived to be only slightly more sour than control for the April harvest, and to be sweeter for the June harvest. When juice from individual replicates was pooled to be more representative of a commercial situation, there was no difference between (+) and (-) Las juice in Valencia.