|Irey, Mike -|
Submitted to: Meeting Abstract
Publication Type: Abstract Only
Publication Acceptance Date: February 10, 2010
Publication Date: N/A
Technical Abstract: The disease, Huanglongbing (HLB), also called greening or yellow dragon disease was first discovered in Florida in 2005. This is a serious disease of citrus that can kill the tree in 5-10 years. It has also been rumored that the disease causes off-flavor in the fruit and subsequent juice that has been described as sour, bitter and metallic. However, no systematic flavor studies have been done. Fruit from diseased trees range from normal looking (asymptomatic) to small, green and lopsided (symptomatic). This research looked at flavor chemistry, including sugars, acids, secondary metabolites and aroma volatiles in juice from asymptomatic fruit from diseased trees versus fruit from healthy trees and also compared symptomatic fruit to normal fruit from diseased trees. These chemical studies were accompanied by sensory tests. Results showed that juice from asymptomatic fruit from diseased trees was not that different from juice from healthy fruit in flavor chemistry or sensory perception. There were more differences between juice from symptomatic (small, green and lopsided) fruit and control (healthy) fruit. Chemical differences included lower sugars, sometimes higher acids and higher levels of the bitter secondary metabolites, limonin and nomilin. Differences in aroma volatiles were less clear and levels of the latter bitter compounds were below taste threshold levels. Likewise, in sensory studies, consumer difference from control tests showed only small to no differences between juice from asymptomatic fruit and controls, but greater differences when symptomatic fruit were involved. Trained panelists picked up more differences, but again differences were minimal for asymptomatic fruit versus controls and greater for symptomatic fruit. Luckily, symptomatic fruit drop off the tree, should be graded out of processing lines if harvested, and so would not likely impact juice quality, especially as individual fruit juice ends up in large juice blends that would likely dilute out any off-flavors.