Effect of Early Detection Huanglongbing on Juice Flavor and Chemistry

摘要

When huanglongbing (HLB) was first discovered in Florida, trees with early symptoms of disease were harvested to determine whether there was any flavor difference between juice made from infected trees but with asymptomatic fruit, and fruit harvestedfrom healthy trees. It is of interest to the processing industry to determine what affect fruit from trees of various stages of infection would have on processed orange juice quality. 'Valencia' oranges were harvested in 2006 from trees that tested positive for Liberibacter asiaticus, the presumed causal agent of HLB, in the early stages of disease development (HLB fruit), and compared to fruit from healthy trees (control). A consumer panel did not perceive differences for taste or smell between controland HLB juice in a triangle test. An experienced panel, however, did perceive that juice from HLB fruit was sweeter than juice from non-HLB fruit. Further tests were performed by using the "difference-from-control" test with filtered or unfiltered juice, to determine the effect of pulp on difference perception. When juice was filtered, panelists could perceive a difference by smell and by taste; when juice was served unfiltered they could only perceive a difference by taste. One of the descriptors thatcame up frequently for the HLB filtered juice for taste difference was again "sweeter." Chemical analyses showed that the juice from HLB fruit was lower in acids and higher in acetaldehyde content and soluble solids-to-acid ratio than from juice from non-HLB fruit, which is in agreement with the "sweeter" perception. Methanol, 2-methyl propanol, and a-pinene were also higher in juice from HLB fruit. Differences in the remaining volatiles were due to the presence of pulp but not to the health status ofthe tree.