2012 Annual Report
1a.Objectives (from AD-416):
1) Assess sensory quality and aroma profile compositions of commercial and new mandarin varieties currently under investigation in breeding programs in the U.S. and Israel.
2) Characterize the effects of postharvest handling procedures (degreening and coating with waxes) and storage conditions (temperature and duration) on sensory quality and aroma profile compositions of various mandarin cultivars.
3) Identify key aroma compounds involved in determining unique mandarin flavor and off-flavors by gas chromatography-olfactometry (GC-O) coupled with a human nose smelling device.
1b.Approach (from AD-416):
Experiments will be conducted with two commercial tangerine cultivars, Fallglo and Murcott, as well as selected new tangerines in the ARS breeding program close to release. Optimum harvest maturity will be determined for new varieties. Degreening and wax treatments will be applied on commercial varieties. Sensory evaluation and volatile analysis will be performed under objectives 1 and 2. Sensory evaluation, GC and GC-olfactometry will be performed under objective 3.
This project is related to Objective 1 of this in-house project: Evaluate the effect of genetics on microbial stability and composition of flavor and healthful compounds – sugars, acids, volatiles, carotenoids, total phenolics, pectin and fiber – in citrus, tomato, and subtropical-bred small fruit breeding lines.
Mandarin hybrids close to release were evaluated for a second year to identify optimum maturity. Commercial cultivars were included in the study for reference. Fruit were evaluated by sensory evaluation (descriptive analysis), sugars, acids and volatile content. There was a sharp contrast in weather pattern between the two seasons, with 2011-2012 being unusually warm compared to 2010-2011. As a result, fruit in 2011-2012 were much sweeter, less sour, and harvest maturity was earlier by one month for most hybrids. The quality evaluation of new mandarin hybrids across their potential seasons of maturity helps growers determine optimum harvest.
A commercial tangerine hybrid, ‘Fallglo’, and its seedless mutant, ‘US Early Pride’ were compared over their harvest season in consumer taste panels. There was no difference between the two varieties for preference. Panelists who preferred ‘Fallglo’ indicated that they perceived more tangerine flavor and sweetness in that hybrid compared to ‘US Early Pride’, and panelists who preferred ‘US Early Pride’ indicated that it was because it had less seeds and it was juicier than ‘Fallglo’. Volatile compounds were analyzed in both cultivars by gas chromatography and olfactometry, and some odorous compounds were detected by the human subjects that were not detected by the instrument. New compounds were reported in tangerines: methional and 1-nonen-3-one.