2013 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 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. And Objective 2: Relate chemical composition to sensory flavor and pathogen resistance data from Objective 1 to determine which compounds are important for flavor or have antimicrobial properties.
There has been an increasing interest in citrus hybrids having Poncirus trifoliata in their background, as P. trifoliata was determined to impart disease resistance to citrus. Fruit of Citrus with P. trifoliata hybrids, with various levels of P. trifoliata, were evaluated for sensory quality, and analyzed for volatiles and non volatile compounds. Four hybrids were evaluated in the fall, and another four in the winter, according to maturity. Hybrids with 1/4 or 1/8 of P. trifoliata in their background presented the most characteristic “Poncirus” flavor, described as green, woody, cooked, and with some bitter and astringent taste and mouthfeel. These hybrids had higher level of sesquiterpenoids and ester compounds than hybrids in which the Poncirus parent was more remote in the family tree. Complex differences in volatiles, limonoid and flavonoid compounds among P. trifoliata hybrids were revealed. Understanding the inheritance of quality traits will help select P. trifoliata hybrids for consumption, as well as provide growers with a choice of cultivars that may be resistant to diseases.