Huanglongbing (HLB) is a plant pathogen responsible for citrus tree decline, reduced harvest yield, reduced juice yield and reduced quality of juice. Pectin is a major co-product from juicing operation and the physico-chemical quality is important to functionality of pectin in food and pharmaceutical applications. Juice and peel from HLB symptomatic and asymptomatic Valencia orange fruits were collected and identified for analysis. Infected fruit were smaller, had lower L* and b* values and highly variable a* values. Juice from infected fruit had higher pectinmethylesterase activity of 1.5 Units/mL, which retained higher activity during 15 days of storage at 4 °C and higher cloud loss. Also, the juice obtained from infected fruit had lower ° Brix (8.5-8.9), higher titratable acidity (0.71-0.88%), lower pH (3.45-3.75) and more variable color parameters compared to control fruit. Pectin extracted from peel of control and infected fruit had similar molecular weight of 154-157 kDa and degree of esterification of 65-67%. Pectin yield was reduced by 6% in infected fruit to 4.18 g/100 g. Total sugars in control fruit were higher, 84.1 μg/mg, compared to infected fruit, 60.7 μg/mg. Major sugars were glucose, galactose, and arabinose, which were higher in control fruit, 25.0, 40.8, and 9.7 μg/mg, compared to 14.5, 27.4, and 8.3 μg/mg in infected fruit. A similar viscosity was observed, 0.015 Pas, in 1% pectin from control or infected fruit. Juice quality was negatively impacted by HLB, however pectin quality and functionality was minimally impacted.

Huanglongbing disease and quality of pectin and fruit juice extracted from Valencia oranges

Macromolecular Chemistry: The Second Century

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ACS Spring 2020 National Meeting & Expo

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