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.

Mitigation of Off-Flavor in Huanglongbing-Affected Orange Juice Using Natural Citrus Non-Volatile Compounds.

Huanglongbing (HLB) disease has reduced orange yield and flavor quality in Florida. Orange juice (OJ) and peel molasses (PM) compounds are "from the named fruit" (FTNF) and were tested for their effects on HLB-affected OJ taste. These and other "target" compounds, reportedly found in citrus, were spiked into off-flavored, HLB-affected reference juices. The spiked juice was evaluated by a sensory panel in comparison with unspiked juice for "sweetness", "sourness", "bitterness", "astringency", and "aftertaste". Of the target compounds, feruloyl putrescine, taxifolin, and neodiosmin most effectively reduced "bitterness", feruloyl putrescine reduced "astringency" and "aftertaste", while feruloyl putrescine and neodiosmin enhanced perceived "sweetness", perhaps due to reduced bitterness. OJ and PM fractions containing reported bitter limonoids, hydroxycinnamates, hesperidin, and/or polymethoxylated flavones enhanced "sourness', "bitterness", "astringency", and "aftertaste", and/or suppressed perceived "sweetness" (perhaps due to enhanced bitterness). Other fractions, containing feruloyl putrescine and/or vicenin-2 enhanced "sweetness" and reduced "bitterness", "sourness", "astringency", and/or "aftertaste". These potentially FTNF compounds may be useful for management of HLB-affected OJ juice flavor.

Effects of polyol type and particle size on flavor release in chewing gum.

The influence of polyol type and particle size on the flavor release profile of chewing gum was investigated in vivo. Four chewing gum samples with an average particle size of 62 or 246 µm for sorbitol and 57 or 184 µm for mannitol were analyzed. Chewing gum formulated with mannitol, in general, had a higher aroma release than chewing gum formulated with sorbitol. Polyol type did not influence the release profile of the high intensity sweeteners (HIS) aspartame and acesulfame K. However, a smaller particle size resulted in a significantly higher release of HIS. The release rate of polyol was not significantly changed by particle size. Sensory analysis was also in agreement with the HIS delivery; the smaller particle size polyol gum was significantly higher in perceived sweetness intensity. In summary, two physical attributes of polyols (solubility and surface area) were reported to uniquely alter the delivery of aroma and taste stimuli.

Effect of Abscission Zone Formation on Orange ( Citrus sinensis) Fruit/Juice Quality for Trees Affected by Huanglongbing (HLB).

Orange trees affected by huanglongbing (HLB) exhibit excessive fruit drop, and fruit loosely attached to the tree may have inferior flavor. Fruit were collected from healthy and HLB-infected ( Candidatus liberibacter asiaticus) 'Hamlin' and 'Valencia' trees. Prior to harvest, the trees were shaken, fruit that dropped collected, tree-retained fruit harvested, and all fruit juiced. For chemical analyses, sugars and acids were generally lowest in HLB dropped (HLB-D) fruit juice compared to nonshaken healthy (H), healthy retained (H-R), and healthy dropped fruit (H-D) in early season (December) but not for the late season (January) 'Hamlin' or 'Valencia' except for sugar/acid ratio. The bitter limonoids, many flavonoids, and terpenoid volatiles were generally higher in HLB juice, especially HLB-D juice, compared to the other samples. The lower sugars, higher bitter limonoids, flavonoids, and terpenoid volatiles in HLB-D fruit, loosely attached to the tree, contributed to off-flavor, as was confirmed by sensory analyses.

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.

Electronic Tongue Response to Chemicals in Orange Juice that Change Concentration in Relation to Harvest Maturity and Citrus Greening or Huanglongbing (HLB) Disease.

In an earlier study, an electronic tongue system (e-tongue) has been used to differentiate between orange juice made from healthy fruit and from fruit affected by the citrus greening or Huanglongbing (HLB) disease. This study investigated the reaction of an e-tongue system to the main chemicals in orange juice that impact flavor and health benefits and are also impacted by HLB. Orange juice was spiked with sucrose (0.2-5.0 g/100 mL), citric acid (0.1%-3.0% g/100 mL) and potassium chloride (0.1-3.0 g/100 mL) as well as the secondary metabolites nomilin (1-30 µg/mL), limonin (1-30 µg/mL), limonin glucoside (30-200 µg/mL), hesperidin (30-400 µg/mL) and hesperetin (30-400 µg/mL). Performance of Alpha MOS sensor sets #1 (pharmaceutical) and #5 (food) were compared for the same samples, with sensor set #1 generally giving better separation than sensor set #5 for sucrose, sensor set #5 giving better separation for nomilin and limonin, both sets being efficient at separating citric acid, potassium chloride, hesperitin and limonin glucoside, and neither set discriminating hesperidin efficiently. Orange juice made from fruit over the harvest season and from fruit harvested from healthy or HLB-affected trees were separated by harvest maturity, disease state and disease severity.

Pharmacokinetics of flavanone glycosides after ingestion of single doses of fresh-squeezed orange juice versus commercially processed orange juice in healthy humans.

Orange juice is a rich source of flavonoids considered beneficial to cardiovascular health in humans. The objective of this study was to analyze the pharmacokinetics of the main flavanone glycosides, hesperidin and narirutin, in humans after the consumption of two styles of orange juice, fresh-squeezed (FOJ) and commercially processed (POJ), differing in their amounts of soluble and insoluble forms of these compounds. Healthy human subjects consumed 11.5 mL/kg body weight of FOJ, and after an interval of 30 days, consumed the same quantity of POJ. The results showed that there were no significant differences in the Tmax of the pharmacokinetic curves for the metabolites of hesperidin and narirutin following the consumption of the two styles of juices, and corrected for differences in doses in the POJ and FOJ, there were also no significant differences in the AUC and Cmax values and percent absorption of these compounds.

Acylphloroglucinol derivatives from Hypericum prolificum.

Three new acylphloroglucinol derivatives have been isolated from the hexane extract of the aerial parts of Hypericum prolificum L.: prolificin A (1), prolifenone A (2), and prolifenone B (3). The structures were elucidated on the basis of extensive 2D NMR and MS data. All three compounds were evaluated for in vitro cell proliferation inhibitory activity against human breast (MCF-7), lung (NCI-H460), CNS (SF-268), stomach (AGS), and colon (HCT-116) tumor cell lines. Prolificin A showed growth inhibition of all cell lines with IC50 values ranging from 23 to 36 microM. Prolifenones A and B were inactive at the concentrations tested.