Huanglongbing (HLB) disease, presumably caused by<i> Candidatus </i>Liberibacter asiaticus was discovered in Florida orange groves in 2005, and since then, has spread all over the State, reducing citrus production by more than 80%. Citrus growers have struggled to maintain fruit production, but the disease has also affected juice quality (flavor and taste). Fruit severely affected by HLB are small, asymmetric, remain green, and the juice is more sour, less sweet and more bitter than juice made with healthy oranges. In general, fruit drop is greater in diseased trees, and fruit that are loosely attached to the treee express more off flavor than those that have intact vascular tissue. Fruit symptomatic for the disease contain less sugar, less ester and sesquiterpene volatiles (i.e. methyl butanoate and valencene), but have a greater content of citric acid, limonoid aglycones, flavonoids and monoterpene hydrocarbons than healthy oranges. Agricultural practices that may affect fruit quality include foliar nutritional sprays, insecticides, thermotherapy, and pre-harvest fungicides. However, nutritional sprays over a period of 5 years did not provide consistent results. It was shown that juice with HLB characteristic off-flavor could be blended with “healthy” juice up to 25% before the off-flavor was detectable. The detection threshold of limonin, the main bitter compound in orange juice, was 4-6 mg/L, but juice with limonin content lower than its threshold could also be perceived as bitter, suggesting complex interactions between sugars, acids and other limonoids and flavonoids in the juice.

What have we learned about orange juice chemistry and sensory quality since huanglongbing was declared a disease in the State of Florida 13 years ago?

2019 Spring National Meeting

The official archive and repository for all ACS Meetings & Expositions abstracts and select posters or presentations.