Physicochemical and Sensory Properties of Cold Pressed Oils from Florida Hamlin and Valencia Oranges Affected by Huanglongbing

Cold pressed oils from huanglongbing (HLB) symptomatic (SY) and asymptomatic (AS) Hamlin and Valencia oranges were assessed for 2 y (2014 to 2015 and 2015 to 2016 seasons) with 2 harvest dates for each orange variety per year. Physicochemical properties (optical rotation, aldehyde content, ultraviolet [UV] absorbance, refractive index, and specific gravity) mandated by the United States Pharmacopeia (USP) for orange oil quality were assessed. Hamlin and Valencia oils showed minor differences in physicochemical properties based upon disease stage. However, all Hamlin oils had aldehyde contents below the USP minimum and Valencia oil from late season SY oranges had specific gravities above the USP maximum. Significant differences based on harvest year were seen for aldehyde content, refractive index, optical rotation, and UV absorbance. While none of these changes led to an oil being out of USP specifications, they indicate a need to monitor the quality of oil every year to ensure a consistent product. Flavor taste panels were performed both years by adding 0.035% oil samples to a uniform orange juice base. Aroma panels were done by smelling pure oil. There were no significant differences between SY and AS oils for flavor, although panelist race was a significant factor in several of the panels. There were significant differences between the aroma of SY and AS oils for both 2015 to 2016 Hamlin Early and Valencia Late samples. Overall, these results show HLB can have an effect on the aroma and USP mandated physicochemical properties of Florida orange oils, although flavor may be unaffected by this plant disease. Practical Application Research on the effect of huanglongbing on the physicochemical properties, taste, and aroma of orange oils has not previously been published. This work is important to those working in the flavor and fragrance industries, for whom cold pressed orange oil and/or its chemical fractions are important products used in the formulation of many beverages, flavors, and perfumes. This work is additionally important to orange juice manufacturers, for whom cold pressed orange oil is a significant byproduct.