Submitted to: Subtropical Technology Conference Proceedings
Publication Type: Abstract only
Publication Acceptance Date: 10/18/2009
Publication Date: 10/22/2009
Citation: Plotto, A., Bredzinski, X., Baldwin, E., Mccollum, G., Irey, M. 2009. Use of electronic tongue and nose sensors to differentiate between juice from greening (Huanglongbing) and healthy fruit. Subtropical Technology Conference Proceedings. 60:37-39. Interpretive Summary:
Technical Abstract: In 2007 and 2008, consumer and descriptive sensory analyses were made of juice from fruit harvested from healthy and Huanglongbing (HLB) affected trees. Differences were sometimes found for flavor, mainly for juice from HLB fruit symptomatic for the disease (small, green, asymmetrical shape) with descriptors such as bitter, sour, metallic, and general off taste (Plotto et al., submitted manuscript; Goodrich-Schneider et al., 2008). Levels of the bitter compounds limonin and nomilin tended to be higher in juice from HLB symptomatic trees and fruit, although not above reported sensory thresholds. Hamlin fruit was harvested in February 2008, and again in January 2009 from a commercial grove, juiced and pasteurized under commercial conditions. The 2008 samples were processed in batches of 200-400 fruit harvested from three replicates of three trees per treatment, while the 2009 juice was processed in one unit of 200-500 fruits per treatment harvested from 15 trees. Treatments included fruit from healthy trees, non-symptomatic fruit from HLB-affected trees and HLB-symptomatic fruit. Samples were presented to a trained panel (>50 hours) for sensory evaluation and analyzed using the Astree® electronic tongue and Prometheus® electronic nose (Alpha-MOS, Toulouse, France). Correlations between sensory and electronic nose and tongue were done using AlphaSoft software V.12. In 2008, Hamlin juice from HLB affected trees was lower in orange and fresh flavor and sweet taste and higher in bitter, metallic, pungent/peppery and astringent flavor and taste (trained panel evaluation). Differences between juice from symptomatic and non-symptomatic fruit were found for sour/fermented and musty/earthy flavor, and juice made with symptomatic fruit was perceived to have a salty/umami taste. In 2009, with a larger sample size, there were no differences between juice from healthy and non-symptomatic HLB fruit for most descriptors except fruity flavor, lower in juice from HLB-affected trees. However, juice from HLB symptomatic fruit was significantly lower in orange aroma and flavor, fresh flavor and sweet taste, and higher for most of the off-flavors. The electronic tongue sensors could clearly differentiate between juice from HLB symptomatic fruit and juice from healthy trees both years. Juice from non-symptomatic HLB fruit was classified between these two samples in 2008, with some overlap between healthy and HLB samples, and undifferentiated from the healthy samples in 2009. There were very good correlations between electronic tongue and sensory panel data. The electronic nose could also separate juice from symptomatic fruit in 2008. Research will be pursued evaluating sensory perception of juice blends from symptomatic, asymptomatic, and healthy fruit, and to relate the electronic nose and tongue classifications with the sensory data. Work will also be done to determine which chemical compounds are correlated with the electronic nose and tongue responses.