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Clewiston, FL, United States

Plotto A.,U.S. Department of Agriculture | Baldwin E.,U.S. Department of Agriculture | McCollum G.,U.S. Department of Agriculture | Manthey J.,U.S. Department of Agriculture | And 2 more authors.
Journal of Food Science | Year: 2010

Some anecdotal reports suggest that infection of citrus trees with Candidatus Liberibacter asiaticus (Las), the suspected causal agent of huanglongbing (HLB) disease, imparts off flavor to orange juice. It is of interest to the industry to know how Las infection affects juice quality with respect to cultivar, maturity, or processing method. Hamlin, Midsweet, and Valencia oranges were harvested over 2 y from trees that tested negative (Las-) or positive (Las+) for Las from different groves and included normal looking (nonsymptomatic) and symptomatic fruit (small, green, and lopsided) from Las+ trees. In the 1st year, fruit were manually juiced, while in the 2nd year, a commercial process was used. Juice from Las+ trees was compared to juice from Las- trees in difference-from-control tests, and by descriptive analysis. Results showed large variability due to tree, harvest date, and cultivar. Juice from Hamlin Las+ trees tended to be more bitter and sour than its Las- counterpart. In contrast, hand processed Valencia juice from Las+ trees was perceived to have some off-flavor and bitterness compared to control, but the following year, commercially processed Valencia juice from Las+ trees was perceived to be only slightly more sour than juice from Las- trees for the April harvest, and to be sweeter for the June harvest. When juice from individual replicates was pooled to be more representative of a commercial situation, there was no difference between Las+ and Las- juice in Valencia. Trained panel differences were noted for juice from Hamlin Las+ fruit, especially for symptomatic fruit.Practical Application: Assumptions that juice made from oranges harvested from Huanglongbing (from infection with Liberibacter sp.) affected trees is off-flavored appeared to be generally more true for Hamlin juice than for Midsweet or Valencia, especially for Hamlin juice made from symptomatic fruit. For Midsweet and Valencia, flavor differences between juice made from fruit harvested from diseased or healthy trees varied greatly between trees, season, and even processing method. Under a commercial processing situation, where juice is blended from several varieties, seasons, and multiple locations, it is expected that off-flavor will not be a major problem. No claim to original US government worksJournal compilation © 2010 Institute of Food Technologists®.

Baldwin E.,U.S. Department of Agriculture | Plotto A.,U.S. Department of Agriculture | Manthey J.,U.S. Department of Agriculture | Mccollum G.,U.S. Department of Agriculture | And 4 more authors.
Journal of Agricultural and Food Chemistry | Year: 2010

More than 90% of oranges in Florida are processed, and since Huanglongbing (HLB) disease has been rumored to affect fruit flavor, chemical and physical analyses were conducted on fruit and juice from healthy (Las -) and diseased (Las +) trees on three juice processing varieties over two seasons, and in some cases several harvests. Fruit, both asymptomatic and symptomatic for the disease, were used, and fresh squeezed and processed/pasteurized juices were evaluated. Fruit and juice characteristics measured included color, size, solids, acids, sugars, aroma volatiles, ascorbic acid, secondary metabolites, pectin, pectin-demethylating enzymes, and juice cloud. Results showed that asymptomatic fruit from symptomatic trees were similar to healthy fruit for many of the quality factors measured, but that juice from asymptomatic and especially symptomatic fruits were often higher in the bitter compounds limonin and nomilin. However, values were generally below reported taste threshold levels, and only symptomatic fruit seemed likely to cause flavor problems. There was variation due to harvest date, which was often greater than that due to disease. It is likely that the detrimental flavor attributes of symptomatic fruit (which often drop off the tree) will be largely diluted in commercial juice blends that include juice from fruit of several varieties, locations, and seasons. © 2009 American Chemical Society.

Glynn N.C.,U.S. Department of Agriculture | Laborde C.,Florida Crystals | Davidson R.W.,League Inc. | Irey M.S.,United States Sugar Corporation | And 3 more authors.
Molecular Breeding | Year: 2013

Brown rust, caused by Pucciniamelanocephala, has had devastating effects on sugarcane (Saccharum spp.) breeding programs and commercial production. The discovery of Bru1, a major gene conferring resistance to brown rust, represented a substantial breakthrough. Markers for Bru1 are the first available for sugarcane molecular breeding. The contribution of Bru1 towards brown rust resistance in the Canal Point (CP) sugarcane breeding program was determined as a means of directing future breeding strategies. Bru1 was detected in 285 of 1,072 (27 %) clones used for crossing; this germplasm represents the genetic base for cultivar development in Florida. The frequency of Bru1 was greatest in CP clones (42 %) and lowest among Louisiana clones (6 %). Bru1 was not detected in clones with year assignments before 1953. However, Bru1 frequency increased from 15 % (assignments 1975-1985) to 47 % in the current decade. The increase coincided with the introduction of brown rust to Florida. Bru1 was detected in 155 (32 %) of 485 parental clones tested for brown rust susceptibility at two field locations. Of clones classed resistant to brown rust, 154 (59 %) contained Bru1, yet none of 100 susceptible clones contained the gene. Bru1 was detected in 667 (44 %) clones in the second clonal stage of selection, 87 % of which were free of brown rust symptoms. Bru1 is the predominant source of resistance in the Florida sugarcane genetic base. Efforts to identify and integrate new brown rust resistance genes must be pursued to minimize risks associated with a future breakdown in major gene resistance provided by Bru1. © 2012 Springer Science+Business Media Dordrecht (outside the USA).

Glaz B.,U.S. Department of Agriculture | Shine Jr. J.M.,Sugar Cane Growers Cooperative of Florida | Irey M.S.,United States Sugar Corporation | Perdomo R.,Florida Crystals Corporation | And 2 more authors.
Agronomy Journal | Year: 2011

Accurate seasonal estimates of fiber are needed to maximize profits whether producing sugarcane (Saccharum spp.) for sucrose or ethanol. The main purpose of this study was to determine the effects of sample date and crop cycle on fiber content of three sugarcane cultivars growing on sand and organic (muck) soils, and secondarily to determine if fiber could be reliably estimated 1 mo before the beginning of the harvest season. From September through February, from 2007-2009, fiber content was estimated from monthly sampled stripped stalks of cultivars CP 72-2086, CP 78-1628, and CP 89-2143 growing in three replications of field plots in south Florida in the plant-cane, first-ratoon, and second-ratoon crop cycles on Pompano fine sand (siliceous, hyperthermic Typic Psammaquent) or Margate sand (Siliceous, hyperthermic Mollic Psammaquent), and Torry muck (euic, hyperthermic Typic Haplosaprist) soils. Linear increases in fiber content ranged from 0.07 to 0.28 g kg-1 d-1. Quadratic models usually predicted maximum fiber content from December through early January. On sand soils, the cultivar rankings were oft en similar to expectations, with fiber content of CP 78-1628 > CP 89-2143 > CP 72-2086. On the muck soil, CP 78-1628 fiber content was high, but differences between CP 72-2086 and CP 89-2143 were not consistent. For all soils, overall means were oft en not indicative of fiber status due to significant, but inconsistent interactions. Researchers should analyze fiber content whenever they analyze sucrose content, and mills should monitor fiber content daily of unique cultivar × crop cycle × soil deliveries. © 2011 by the American Society of Agronomy.

Chen J.,U.S. Department of Agriculture | Deng X.,South China Agricultural University | Irey M.,United States Sugar Corporation | Civerolo E.,U.S. Department of Agriculture
Phytopathology | Year: 2010

Huanglongbing (HLB) (yellow shoot disease) is a highly destructive disease that threatens citrus production worldwide. The disease was first observed in Guangdong, P. R. China, over 100 years ago, and was found in Florida, United States, in 2005. 'Candidatus Liberibacter asiaticus' has been associated with HLB in many citrus-growing regions around the world, including Guangdong and Florida. The global epidemiology of HLB, as well as management of the disease, relies on knowledge of 'Ca. L. Asiaticus' populations in different geographical regions around the world. In this study, we identified a genetic marker containing small tandem repeats in the genome of 'Ca. L. Asiaticus' and comparatively analyzed the tandem repeat numbers (TRNs) in 'Ca. L. Asiaticus' populations from Guangdong and Florida. Analyses of TRNs showed that the bacterial population in Guangdong was different from that in Florida. The Guangdong population consisted predominately of strains with a TRN of 7 (TRN7) at a frequency of 47.6%. The Florida population consisted predominately of strains with a TRN of 5 (TRN5) at a frequency of 84.4%. TRNs ranged from 3 to 16. The apparent absence of TRNs of 9, 10, 11, and 12 separated the bacterial strains into two groups: TRNs < 10 (TRN<10) and TRNs > 10 (TRN>10). In Florida, TRN<10 strains (103/109, or 94.5%) were widely distributed in all HLB-affected counties. TRN>10 strains (6/109, or 5.5%) were found in central Florida. This is the first report documenting the differentiation of 'Ca. L. Asiaticus' populations between Asia and North America and the possible presence of two differentially distributed genotypes of 'Ca. L. Asiaticus' in Florida.

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