Sensory quality of Citrus scion hybrids with Poncirus trifoliata in their pedigrees.

Hybrids of Poncirus trifoliata L. Raf. with Citrus have shown degrees of tolerance to the deadly citrus greening disease, hence prompting interest as potential commercial varieties. Although P. trifoliata is known to produce fruit that is inedible, fruit from many advanced hybrid trees have not been evaluated for their quality potential. The sensory quality of selected Citrus hybrids with varying degrees of P. trifoliata in their pedigrees is reported herein. Four Citrus × P. trifoliata hybrids developed through the USDA Citrus scion breeding program-1-76-100, 1-77-105, 5-18-24, and 5-18-31-had acceptable eating quality and sweet and sour taste, with mandarin, orange, fruity-noncitrus, and floral flavors. On the other hand, hybrids with higher proportion of P. trifoliata in their pedigrees, US 119 and 6-23-20, produced a juice characterized by green, cooked, bitter, and Poncirus-like flavor and aftertaste. Partial least square regressions revealed that the Poncirus-like off-flavor is likely due to a combination of higher than typical amounts of sesquiterpene hydrocarbons (woody/green odor), monoterpenes (citrus/pine), and terpene esters (floral) and a lack of aldehydes with typical citrus odor (octanal, nonanal, and decanal). Sweetness and sourness were mostly explained by high sugars and acids, respectively. Further, carvones and linalool contributed to sweetness in the samples from early and late seasons, respectively. In addition to highlighting chemical contributors to sensory descriptors in Citrus × P. trifoliata hybrids, this study provides useful information on sensory quality for future citrus breeding efforts. PRACTICAL APPLICATION: The relationships between the sensory quality and secondary metabolites of Citrus × P. trifoliata hybrids described in this study help identify disease-resistant Citrus scion hybrids with acceptable flavor and help mobilize this resistance in future breeding efforts. It also shows potential of such hybrids to be commercialized.

Effect of fruit maturity on volatiles and sensory descriptors of four mandarin hybrids.

Mandarins (or tangerines) are mainly consumed as fresh fruits due to the ease of peeling and desirable flavor. Sweetness, acidity, and flavor of mandarin are the most important criteria for consumer preference. The objective of this study was to evaluate the effects of harvest date on sensory and chemical components of four mandarin cultivars (Murcott, 411, Temple, and 'LB8-9' Sugar Belle®). Volatiles were extracted from the headspace of juice samples with solid phase microextraction (SPME) and analyzed using gas chromatography-mass spectrometry (GC-MS). The optimum harvest window for eating quality of 411 was late January to mid-February (soluble solids content [SSC]/titratable acidity [TA]: 11.3 to 14.0), Sugar Belle® fruits were best tasted when harvested from mid- to end of January (SSC/TA: 14.1 to 16.1), and February was the best month for harvesting Murcott (SSC/TA: 13.10 to 18.0) and Temple (SSC/TA:10.3 to 12.50). Sensory perception of sweetness, ripeness, and juiciness increased as SSC/TA increased while sourness and bitterness decreased. Pumpkin flavor, an indicator of overripe fruit, was mainly noticed late in the season. Tangerine flavor tended to decrease, whereas fruity-noncitrus flavor tended to increase with fruit maturity. Monoterpenes were the most abundant volatiles and tended to decrease with fruit maturity, whereas alcohols, esters, and aldehydes increase. Aldehydes, esters, and alcohols were positively correlated with sweetness, ripeness, juiciness, and fruity characteristics, and negatively with sourness and bitterness. On the other hand, monoterpenes were positively correlated with bitterness and tangerine flavor, and negatively correlated with sweetness and fruity-noncitrus flavor. The highest number of esters was found in Temple, whereas Murcott and 411 were high in aldehydes.

Development of delayed bitterness and effect of harvest date in stored juice from two complex citrus hybrids.

BACKGROUND: Mandarins and mandarin hybrids have excellent flavor and color attributes, making them good candidates for consumption as fresh fruit. When processed into juice, however, they are less palatable, as they develop delayed bitterness when stored for a period of time. In this study the kinetics of delayed bitterness in two citrus mandarin hybrid siblings, 'Ambersweet' and USDA 1-105-106, was explored by sensory and instrumental analyses. In addition to the bitter limonoids, other quality factors (i.e. sugars, acids, pH, soluble solids content (SSC), titratable acidity (TA) and the ratio SSC/TA) were also measured. RESULTS: The two citrus hybrid siblings had different chemical profiles, which were perceived by taste panels. USDA 1-105-106 developed delayed bitterness when the juice was stored for more than 4 h, similar to juice from 'Navel' oranges, but 'Ambersweet' did not. Bitterness in 'Ambersweet' was more affected by harvest maturity, as juice from earlier harvest had lower SSC but higher TA and bitter limonoids. CONCLUSION: Since juice of USDA 1-105-106 shows delayed bitterness when stored for more than 4 h, this cultivar is not suitable for juice processing. Our finding that siblings can differ in chemical and sensory properties emphasize the importance of post-processing storage studies before releasing cultivars for juice.