Robert A. Saftner

United States Department of Agriculture, Washington, D. C., DC, United States

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Publications (49)78.79 Total impact

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    ABSTRACT: BACKGROUND: The exotic pepper species Capsicum baccatum, also known as the aji or Peruvian hot pepper, is comprised of wild and domesticated botanical forms. The species is a valuable source of new genes useful for improving fruit quality and disease resistance in C. annuum sweet bell and hot chile pepper. However, relatively little research has been conducted to characterize the species, thus limiting its utilization. The structure of genetic diversity in a plant germplasm collection is significantly influenced by its ecogeographical distribution. Together with DNA fingerprints derived from AFLP markers, we evaluated variation in fruit and plant morphology of plants collected across the species native range in South America and evaluated these characters in combination with the unique geography, climate and ecology at different sites where plants originated. RESULTS: The present study mapped the ecogeographic distribution, analyzed the spatial genetic structure, and assessed the relationship between the spatial genetic pattern and the variation of morphological traits in a diverse C. baccatum germplasm collection spanning the species distribution. A combined diversity analysis was carried out on the USDA-ARS C. baccatum germplasm collection using data from GIS, morphological traits and AFLP markers. The results demonstrate that the C. baccatum collection covers wide geographic areas and is adapted to divergent ecological conditions in South America ranging from cool Andean highland to Amazonia rainforest. A high level of morphological diversity was evident in the collection, with fruit weight the leading variable. The fruit weight distribution pattern was compatible to AFLP-based clustering analysis for the collection. A significant spatial structure was observed in the C. baccatum gene pool. Division of the domesticated germplasm into two major regional groups (Western and Eastern) was further supported by the pattern of spatial population structure. CONCLUSIONS: The results reported improve our understanding of the combined effects of geography, ecology and human intervention on organization of the C. baccatum genepool. The results will facilitate utilization of C. baccatum for crop improvement and species conservation by providing a framework for efficient germplasm collection management and guidance for future plant acquisitions.
    BMC Genetics 08/2012; 13(1):68. · 2.81 Impact Factor
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    ABSTRACT: Variability in the concentrations of capsaicinoids and capsaicinoid analogs which contribute to flavor and nutritional quality of Capsicum baccatum peppers is not well understood. Using reversed-phase liquid chromatography with ultraviolet absorbance and electrospray mass spectroscopic detection, we evaluated capsaicinoids and their analogs in mature green fruit from 224 non-cultivated and cultivated accessions of C. baccatum var. baccatum, C. baccatum var. pendulum, C. baccatum var. umbilicatum and C. baccatum var. praetermissum acquired from the USDA/ARS Capsicum genebank in Griffin, GA. Concentrations of total capsaicinoids and associated pungency scores among accessions ranged from 3 to 12,522 microg/g dry weight and 46 to 194,278 Scoville heat units (SHU), respectively, with median values of 3,165 microg/g dry weight and 47,667 SHU. Likewise, concentrations of individual capsaicinoids ranged from essentially none (< 2) to 8,323, 7,409, 996, 301, 293, 163, 126, 115, and 30 microg/g dry weight for capsaicin, dihydrocapsaicin, nordihyrocapsaicin, coeluting homocapsaicins, N-vanillyl decanoate, homodihydrocapsaicin II, N-vanillyl octanoate, homodihydrocapsaicin I and norcapsaicin, respectively, with associated median values of 1,918, 818, 151, 49, 35, 21, 7, 6, and 5 microg/g dry weight. Capsaicin was generally the most abundant capsaicinoid amongst accessions followed by dihyrocapsaicin and nordihydrocapsaicin. The total concentration of essentially non-pungent capsaicinoid analogs, capsiate, dihydrocapsiate, capsiconiate and dihydrocapsiconiate, ranged between non-detectable and 1,315 microg/g dry weight with a median value of 160 microg/g dry weight. Variability in the concentrations of capsaicinoids, and the capsinoid and capsiconinoid capsaicinoid analogs was sufficiently large that genetic manipulation may enable the development of improved C. baccatum cultivars with novel flavor and nutritional attributes and the introgression of these desirable attributes into pepper (C. annuum) breeding lines.
    2012 ASHS Annual Conference; 08/2012
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    ABSTRACT: Unblemished fully ripe fruit from five day-neutral strawberry cultivars were harvested on two separate dates and evaluated for ascorbic acid (AsA), fruit sugars, and phenolic composition. Individual phenolics were determined by HPLC, and total phenolics by Folin–Ciocalteu (F–C) and by a ‘new’ assay: Fast Blue BB (FBBB), which detects phenolics directly. FBBB reported an average 2.9-fold greater concentration of total phenolics than F–C, had a significant correlation (r = 0.80; P = 0.001) with total phenolics via HPLC and did not interact with AsA or sugars, whereas F–C, an indirect detection assay for total phenolics, appeared to under-report total phenolic concentrations, had no significant correlation (r = 0.20) with total phenolics via HPLC or with sugars, but had a significant correlation (r = 0.64; P = 0.05) with total AsA. Results from this study indicated that previous studies of strawberry fruit, using the standard indirect F–C assay, have greatly underestimated the total phenolics content and that this assay should be replaced in future studies by the FBBB assay.
    Journal of Food Composition and Analysis 08/2012; 27(1):102–107. · 2.09 Impact Factor
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    Gene E Lester, Robert A Saftner
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    ABSTRACT: One distinguishing conclusion found in most reviews of research studies comparing organically and conventionally grown produce is that variables shared alike by organic and conventional produce during production, harvest, and postharvest handling and storage were not applied. As a result, accurate and meaningful conclusions comparing the nutritional quality of organic and conventional produce are difficult to ascertain. Pairing common production variables such as the physical, biological, and chemical/nutritional attributes of soils, the irrigation sources and amounts, crop varieties, crop maturities and harvest dates, pre- and postharvest processing, handling, and/or storage methods, individually and collectively, provide greater clarity as to how inputs unique to organic and conventional systems affect produce quality. Variables to be paired during production, harvest, and postharvest handling and storage studies comparing organic and conventional produce are discussed along with findings indicating that organic crops often have higher dry matter, ascorbic acid, phenolic, and sugar and lower moisture, nitrate, and protein contents and yields than conventionally grown crops. Recent studies of nutritional quality in organic versus conventional produce also indicate that soil nitrogen delivery rates strongly affect nutritional quality. Nitrogen profiling is a promising new approach to improving the nutritional quality of both organic and conventional produce.
    Journal of Agricultural and Food Chemistry 09/2011; 59(19):10401-6. · 3.11 Impact Factor
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    ABSTRACT: With 3 figures and 4 tablesAbstractPenicillium expansum and Colletotrichum acutatum cause blue mould and bitter rot of apples during storage which results in significant economic losses. Resistance to these pathogens in commercial apple cultivars has not been documented in the literature. An apple germplasm collection, from the centre of origin in Kazakhstan, is maintained in Geneva, New York. This collection represents a more diverse apple gene pool than commercial cultivars and was evaluated for resistance to the pathogens that cause blue mould and bitter rot. Resistance reactions were skewed towards susceptibility for both fungi and comprised the majority of accessions examined. However, resistance to P. expansum was confirmed in select accessions over multiple years. Maturation patterns and quality indices for soluble solids and acidity, which may also affect susceptibility, were highly variable and represent the genetic diversity of the germplasm collection. Resistance in four accessions to C. acutatum and two accessions resistant to both P. expansum and C. acutatum are reported here for the first time. Data from this study will serve as a foundation for conventional apple breeding programmes and molecular genetics investigations to provide resistance against blue mould and bitter rot in commercial apple varieties.
    Plant Breeding 07/2011; 130(4):481 - 486. · 1.18 Impact Factor
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    ABSTRACT: With 3 figures and 4 tables AbstractPenicillium expansum and Colletotrichum acutatum cause blue mould and bitter rot of apples during storage which results in significant economic losses. Resistance to these pathogens in commercial apple cultivars has not been documented in the literature. An apple germplasm collection, from the centre of origin in Kazakhstan, is maintained in Geneva, New York. This collection represents a more diverse apple gene pool than commercial cultivars and was evaluated for resistance to the pathogens that cause blue mould and bitter rot. Resistance reactions were skewed towards susceptibility for both fungi and comprised the majority of accessions examined. However, resistance to P. expansum was confirmed in select accessions over multiple years. Maturation patterns and quality indices for soluble solids and acidity, which may also affect susceptibility, were highly variable and represent the genetic diversity of the germplasm collection. Resistance in four accessions to C. acutatum and two accessions resistant to both P. expansum and C. acutatum are reported here for the first time. Data from this study will serve as a foundation for conventional apple breeding programmes and molecular genetics investigations to provide resistance against blue mould and bitter rot in commercial apple varieties.
    Plant Breeding 01/2011; 130(4). · 1.18 Impact Factor
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    ABSTRACT: Capsicum baccatum is one of five domesticated pepper species which, despite its morphological and ecological variability, has been underexploited for germplasm improvement. Utilizing a broad spectrum of domesticated and wild C. baccatum germplasm, we utilize AFLP markers to describe the species’ molecular diversity and population structure in the South American gene pool. Analysis of molecular variance (AMOVA) revealed greater genetic diversity in the wild form of C. baccatum (C. baccatum var. baccatum) than in the domesticated form of the species (C. baccatum var. pendulum). Both Bayesian and distance based clustering analysis, as well as principal coordinates analysis (PCA), concordantly demonstrated admixture/shared ancestry between wild and cultivated C. baccatum botanical varieties. Two principal genetic groups were identified in the domesticated C. baccatum accessions largely based on their geographic distribution in South America. One group was predominated by accessions from the western territories of the species’ distribution (Peru, Colombia, Ecuador, Bolivia, Chile and northwestern Argentina) and the second by accessions from the eastern regions, Paraguay and eastern Argentina). The two genetic groups overlapped in the geographic location of present-day Bolivia. The grouping pattern suggested that C. baccatum was domesticated in multiple sites and that its evolution took two lineages followed by lineage differentiation. The wild accessions most closely related to the cultigens were found in the highlands of Peru and Bolivia, which support the early hypothesis that this region is one of the domestication sites of this species. A Bayesian assignment analysis demonstrated that Brazilian wild forms of C. baccatum were genetically distant to all other accessions and made little to no contribution to the domesticated genepool. Moreover, results of clustering analysis suggested that C. baccatum likely originated from present day Paraguay. Analysis of inter-specific relationships across selected Capsicum species supported independent lineages for the two crossability groups within Capsicum, the baccatum species-complex (including C. baccatum) and the annuum species-complex (including C. annuum, C. chinense and C. frutescens). However, the results did not support taxonomic distinction of C. baccatum var. umbilicatum from C. baccatum var. pendulum. The present study provides new insights into the domestication of C. baccatum. The results will be useful for identifying accessions for crop improvement and guiding the development of in situ and ex situ conservation programs.
    Genetic Resources and Crop Evolution 01/2011; · 1.59 Impact Factor
  • Elena Albrecht, John R. Stommel, Robert A. Saftner
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    ABSTRACT: Variability in the concentrations of free sugars, organic acids and capsaicinoids that contribute to fruit flavor in Capsicum baccatum is not well understood. We evaluated mature green fruit of >230 non-cultivated and cultivated accessions of C. baccatum var. baccatum and C. baccatum var. pendulum acquired from the USDA/ARS Capsicum genebank in Griffin, GA. Concentrations (mg/100 mL juice extract) of sucrose, glucose and fructose in fruit ranged from 0 (not detected) to 451, 177 to 3,012, and 38 to 1,241, respectively, with associated median values of 5, 1,154 and 541. Total sugar concentration ranged from 0.3 to 4.0% with a median value of 1.7%. Concentrations of organic acids ranged from 20 to 2,016, 0 to 86, and 0 to 457 mg/100 mL juice extract for citric, malic and isocitric acids, respectively, with associated median values of 477, 35, and 8 mg/100 mL extract. Citric acid was generally the predominant acid among accessions. Concentrations of capsaicinoids among accessions ranged from 0 to 8,961, 7,858, 680, 752, and 324 mg/g dry weight for capsaicin, dihydrocapsaicin, nordihyrocapsaicin, homocapsaicins and homodihydrocapsaicins, respectively, with associated median values of 2,063, 888, 180, 71, and 35 mg/g dry weight. Capsaicin was generally the most abundant capsaicinoid. Pungency among accessions ranged from 116 to 214,531 Scoville heat units/g dry weight with a median value of 55,300. Variability in the concentrations of free sugars, organic acids and capsaicinoids is sufficiently large that genetic manipulation may enable the development of improved C. baccatum cultivars with novel flavors and the introgressions of desirable flavor attributes into bell pepper (C. annuum) breeding lines.
    2010 ASHS Annual Conference; 08/2010
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    ABSTRACT: The genus, Capsicum, is native to the tropics of Central and South America. C. annuum is the most widely cultivated and economically important Capsicum species today. Four additional domesticated Capsicum species include C. frutescens, C. chinense, C. baccatum and C. pubescens. Approximately 25 additional wild Capsicum species are recognized but lack extensive study on their biology. Utilizing morphological, chemical and sensory analysis and molecular markers, we have assessed intraspecific variation within 250 C. baccatum accessions obtained from the USDA, ARS, PGRCU. A smaller number of C. annuum, C. chinense and C. frutescens accessions were similarly evaluated. Domesticated types of C. baccatum are designated as C. baccatum var. pendulum and wild forms as C. baccatum var. baccatum. C. baccatum var. pendulum is widely distributed in Central and South America whereas the wild form, C. baccatum, is centered in Bolivia and surrounding areas. Similar to a number of other Capsicum species, C. baccatum pod types are diverse and fruit size, pigmentation, and flavor attributes exhibited considerable variability. Fruit size ranged from very small round fruit (0.5 cm diameter) typical of C. baccatum var. baccatum to tapered elongate (12-15 cm length) fruit for C. baccatum var. pendulum. Mature fruit pigmentation varied from yellow to orange to red. Fruit flavor varied from mild to very pungent with presence or absence of unique aromatics and flavors. Principle components analysis based upon marker diversity identified two major clusters containing C. baccatum var. pendulum and four smaller, additional clusters. The latter consisted of a single cluster containing the majority of the C. baccatum var. baccatum accessions and three additional clusters represented by both forms of the species. A tendency for clustering of accessions based upon their geographic origin was evident. The results of the genetic diversity analysis will be discussed in relation to fruit phenotype attributes.
    2009 ASHS Annual Conference; 07/2009
  • Elena Albrecht, John Stommel, Eunhee Park, Robert A. Saftner
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    ABSTRACT: Capsicum germplasm includes five domesticated species and 25 wild species. C. annuum is widely grown worldwide and includes the economically important sweet bell pepper. Related germplasm resources offer rich diversity for genetic improvement of C. annuum. Introgression of novel fruit flavor attributes from domesticated and wild species affords new opportunities to improve pepper fruit flavor. We have identified Capsicum accessions with unique aroma and flavor attributes. A gas chromatography (GC)-mass spectroscopy-olfactory detection system was utilized to characterize fruit aroma volatiles, and GC-flame ionization detection was used for quantification of TMS sugars and organic acids. Over 150 volatiles have been identified in selected accessions, half of which have not been characterized previously in fruit of C. annuum. Some accessions with unique flavor attributes were distinct from other accessions, particularly C. annuum cultivars, in having relatively high concentrations of various esters with fruity, floral or uncharacterized aromas, sesqueterpenes with woody, spicy, herbal and uncharacterized aromas and relatively polar volatiles some of which had malodorous odors. Many individual volatiles, mostly aldehydes, ketones and alcohols, having ethereal or green-grassy aromas and two pyrazines having ginseng or bell pepper aromas were present in all accessions evaluated. Concentrations of most volatiles decreased during fruit ripening whereas 1-penten-3-ol, 3-pentanone, 1-hexanol and (E)-2-hexen-1-ol increased. Preliminary evaluations indicate variations in the concentrations of ascorbic, citric, malic, oxalic, fumaric, pyroglutamic, and/or shikimic acids, and sucrose, glucose and fructose. Genes that influence flavor quality in Capsicum are being identified by analysis of intra- and inter-specific populations. Phenotypic characterization of over 250 Capsicum accessions and select inbred backcross populations should provide breeding material for development of C. annuum stocks with enhanced fruit flavor.
    2009 ASHS Annual Conference; 07/2009
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    Robert A. Saftner, Gene E. Lester
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    ABSTRACT: A novel hybrid muskmelon has been bred specifically for use by the fresh-cut industry in winter. Quality characteristics of fresh-cut pieces from the hybrid were compared to those of its inbred parental lines and to those of a commercial netted muskmelon (cantaloupe) and a non-netted muskmelon (honeydew) fruit available in winter. Pieces from hybrid and female line fruit had higher soluble solids content (SSC) and firmness, and lower aromatic volatile concentrations compared to those from the male line fruit. Pieces from hybrid fruit also had higher SSC (>3%) and were firmer (>5 N) than commercial fruit available during the winter, and had twice the aromatic volatile concentration of commercial honeydew and a more intense orange hue than commercial muskmelon. Consumers rated the flavor, texture, sweetness and overall eating quality of the hybrid higher than its inbred parents and winter-available honeydew and as well as or better than winter-available muskmelon. Hybrid fruit stored 5 weeks at 1 °C under modified atmospheric conditions, then fresh-cut and stored 14 d in air at 5 °C maintained good quality (firmness = 51 N, SSC > 12%, β-carotene and ascorbic acid concentrations = 18 and 182 mg kg−1, respectively), and showed no signs of tissue translucency or surface pitting despite microbial populations >11 log10 kg−1. The results indicate that the novel hybrid muskmelon is a promising new melon type for fresh-cut processing and marketing, at least during the winter season.
    Postharvest Biology and Technology. 01/2009;
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    J.H. Bai, R.A. Saftner, A.E. Watada, Y.S. Lee
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    ABSTRACT: Fresh-cut cantaloupe cubes were placed in film-sealed containers in which the internal gas mixture was attained naturally (nMAP), was flushed with 4 kPa O2 plus 10 kPa CO2 (fMAP), or was maintained near atmospheric levels by perforating the film (PFP). While both nMAP and fMAP maintained the salable quality of melon cubes for 9 d at 5 degrees C, fMAP maintained quality better than nMAP. The benefit of fMAP was indicated by better color retention, and by reduced translucency, respiration rate, and microbial population compared with nMAP. Shelf life of cubes in PFP was only 5 to 7 d at 5 degrees C, and its rapid decline was due to tissue translucency and/or off-odor development.
    Journal of Food Science 10/2008; · 1.78 Impact Factor
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    ABSTRACT: We compared the instrumental and sensory quality characteristics of blueberry fruit from ten highbush (Vaccinium corymbosum L.) cultivars, Chanticleer, Weymouth, Hannah's Choice, Duke, Bluecrop, Coville, Berkeley, Bluegold, Elliott and Lateblue and two rabbiteye (Vaccinium virgatum Aiton) cultivars, Coastal and Montgomery, grown in New Jersey. Cultivars varied in sensory intensity and acceptability scores. Highbush cultivars, Coville and Hannah's Choice, scored highest among the cultivars in sensory scores for intensity of blue color, juiciness, sweetness and blueberry-like flavor and for acceptability of appearance, color, fruit size, sweet/tart balance, flavor and overall eating quality. In contrast, rabbiteye cultivars, Coastal and Montgomery, and the highbush cultivars, Elliott and Weymouth, scored lowest among the cultivars in sensory scores for intensity of bursting energy, skin toughness, texture during chewing, juiciness, and blueberry-like flavor and for acceptability of appearance, color, fruit size, flavor and overall eating quality. Analytical quality characteristics of surface color, size, compression firmness, soluble solids content (SSC), pH, titratable acidity (TA), SSC/TA ratio, and aromatic volatile concentration also varied among cultivars, but no instrumental measurement adequately predicted consumer acceptability scores. The overall eating quality of blueberry fruit was best correlated with flavor scores followed by sensory scores for intensity of juiciness, bursting energy and sweetness and for acceptability of appearance.
    Postharvest Biology and Technology 07/2008; · 2.45 Impact Factor
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    ABSTRACT: A mixture of two yeast antagonists, Metschnikowia pulcherrima and Cryptococcus laurentii, originally isolated from apples and exhibiting greater biocontrol activity against blue mold of apple than either yeast applied alone, were used in combination with sodium bicarbonate (SBC) in a pilot test in which treated fruit were stored under commercial controlled atmosphere (CA) storage conditions. Conidia of Penicillium expansum, antagonists cells and SBC were added to the drench solution. The treatments were applied to apples by drenching entire bins filled with apples containing 100 wounded fruit evenly distributed among five positions in each bin. The treated fruit were stored in commercial CA storages for approximately six months in the 2005-2006 and 2006-2007 storage seasons and then evaluated for incidence of decay. In both years, the treatments with the antagonist alone or in combination with SBC were equally effective and reduced blue mold incidence by 84-97% in 2005-2006 and 73-82% in 2006-2007. SBC alone significantly reduced blue mold incidence compared to the non-treated control but was less effective than the antagonist alone or in combination with SBC. This pilot test showed that the combination of these two antagonists and SBC can be an effective decay control method under commercial CA conditions, confirming results from our earlier laboratory studies using similarly treated fruit stored under CA conditions.
    01/2008;
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    Gene E. Lester, Robert A. Saftner
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    ABSTRACT: Year-round demand for fresh-cut produce, such as muskmelon (Cucumis melo L. Reticulatus group) fruit, can include importation of whole-fruit from as far away as Chile, requiring expensive air shipments. Surface shipments would reduce these transportation expenses but would also require a longer shelf-life fruit than what is now commercially available to withstand the shipping/storage time frame of up to 5 weeks prior to fresh-cut processing. Current muskmelon cultivars have a fruit storage life of up to 2 weeks. In this 2-year study, we compared the marketable quality and phytonutrient attributes of a novel hybrid with its muskmelon parental lines (ultra-firm female × commercial muskmelon cultivar type male) up to 5 weeks at 1 or 5 °C. At harvest whole hybrid fruit were larger (33–37% heavier) than its parental lines, and had an external firmness equal to its female parent. The external and internal firmnesses of the female parent were on average 4.5-fold and 3.6-fold firmer, respectively, than those of the male parent. Compared to its male parent, the internal tissue of hybrid fruit was relatively sweeter, more intensly orange, had a higher concentration of β-carotene, had a seven-fold higher concentration of 5-methyltetrahydrofolate (folic acid), had fewer internal disorders, and reduced senescence. The aforemetioned tissue firmness of hybrid fruit would make it highly suitable to withstand surface shipments of up to 5 weeks; and the aforementioned quality characteristics would make it likely preferable to consumers both taste-wise and nutritionally as a fresh-cut product.
    Postharvest Biology and Technology. 01/2008;
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    ABSTRACT: ‘Golden Delicious’ apples were wound-inoculated with Penicillium expansum and treated with various combinations of sodium bicarbonate and two antagonists (Metschnikowia pulcherrima, Cryptococcus laurentii), and then stored in air or controlled atmosphere (CA = 1.4 kPa O2 and 3 kPa CO2) for 2 or 4 months at 1 °C. The antagonists survived and their populations increased during both air and CA storage. The antagonists alone reduced blue mold but were more effective when combined. Sodium bicarbonate tended to reduce lesion size when used with these antagonist, either when they were used alone or combined. Storage under CA conditions also increased the effectiveness of both antagonist, when used alone or in combination. The only treatment that completely eliminated P. expansum-incited decay was the combination of the two antagonists and sodium bicarbonate on fruit stored under CA conditions. The proper combination of alternative control measures can provide commercially acceptable long-term control of fruit decay and could help reduce our dependency on fungicides.
    Postharvest Biology and Technology 09/2007; · 2.45 Impact Factor
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    ABSTRACT: Maintaining the postharvest quality of fresh-cut fruit after processing and throughout distribution and marketing is a major challenge facing the fresh-cut fruit industry. Analytical quality characteristics of packaged fresh-cut watermelon slices from non-treated and 1-methylcyclopropene (1-MCP)- and/or ethylene-treated whole fruit were investigated. Freshly harvested seedless watermelon (‘Sugar Heart’) were stored 7–14 days in air before exposure to 0, 0.5 or 1.0 μL L−1 1-MCP for 18 h followed by 5 days exposure to 0 or 10 μL L−1 ethylene, all at 20 °C. Following treatment, fruit were processed into wedge-shaped slices, packaged into rigid trays sealed with a high oxygen transmission rate film overlap and stored 1, 6 or 12 days at 5 °C. During storage, fresh-cut watermelon slices from non-treated and 1-MCP- and 1-MCP + ethylene-treated whole fruit maintained similar respiration rates and internal atmospheres of CO2 and O2 and were of similar quality with total aromatic volatile concentrations decreasing and puncture firmness, soluble solids content (SSC), cut surface pH and color remaining relatively stable. In contrast, fresh-cut slices from fruit treated with ethylene alone had higher respiration rates and modified package atmospheres containing more CO2 and O2; lower firmness, SSC and chromaticity values; higher pH and an altered volatile profile compared to those of slices from non-treated and 1-MCP- and 1-MCP + ethylene-treated fruit. The 22 most abundant volatiles were various aldehydes, alcohols and ketones. During storage, many individual volatiles decreased in concentration but some increased including (Z)-6-nonen-1-ol, a volatile having a pumpkin-like aroma. The results indicated that low dosage 1-MCP treatments prior to ethylene exposure of whole watermelons prevented ethylene-mediated quality deterioration in fresh-cut slices stored under modified atmosphere conditions at 5 °C.
    Postharvest Biology and Technology 04/2007; · 2.45 Impact Factor
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    ABSTRACT: Maintaining the sensory, microbial and postharvest quality of fresh-cut fruit after processing and throughout distribution and marketing is a major challenge facing the fresh-cut fruit industry. Fresh-cut chunks of orange-fleshed honeydew (‘Honey Gold’, ‘Orange Dew’, ‘Temptation’ and three breeding lines) and green-fleshed honeydew (‘Honey Brew’) and an orange-fleshed cantaloupe (‘Cruiser’) harvested at commercial and full-slip maturities were compared after storage for 0–11 days in air at 5 °C. Fresh-cut cantaloupe had higher respiration and ethylene production rates, aromatic volatile concentrations, and β-carotene/chroma and orange hue (except ‘Orange Dew’) than those of honeydew whereas honeydew chunks generally had higher soluble solids content (SSC), Kramer firmness and lower microbial counts than cantaloupe chunks. All genotypes had similar ascorbic acid levels. During storage, analytical quality characteristics of fresh-cut chunks from all genotypes were well maintained even though microbial populations increased especially on cantaloupe chunks. Consumers liked the flavor, texture, sweetness and overall eating quality of the orange-fleshed honeydew genotypes as well as or better than those of cantaloupe and green-fleshed honeydew. ‘Orange Dew’ scored highest in appearance and had the highest β-carotene concentration, chroma and orange hue among orange-fleshed honeydew genotypes whereas ‘Temptation’ generally scored highest for flavor intensity and acceptability and overall eating quality; and it had the highest aromatic volatile concentrations among the orange-fleshed honeydews. Many individual volatiles were identical in cantaloupe and honeydews; however, honeydew genotypes, particularly ‘Temptation’, were distinctive from cantaloupe and green-fleshed honeydew in having relatively high levels of various nonenyl and nonadienyl acetates having honeydew-like or uncharacterized aromas. Fresh-cut chunks from full-slip melons generally had higher analytical and sensory quality characteristics but higher microbial counts and lower shelf stability compared to those from commercially mature fruit. The results indicate that orange-fleshed honeydews are a promising new melon type for fresh-cut processing.
    Postharvest Biology and Technology 11/2006; · 2.45 Impact Factor
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    ABSTRACT:   The effects of exogenous ethylene, 1-methylcyclopropene (1-MCP), or both on microbial growth on watermelon fruit and watermelon slices were investigated. Freshly harvested seedless watermelons (Citrullus lanatus, cv. Sugar Heart) were treated with 0.5 or 1.0 ppm 1-MCP, 10 ppm ethylene, 1-MCP + ethylene, or left untreated as controls. Fruits were processed into wedge-shaped slices, packaged into rigid trays sealed with a polyethylene film with a 29.2 pmol s−1 m−2 Pa−1 oxygen transmission rate. The slices were evaluated after 0-, 6-, and 12-d storage at 5 °C. Ethylene treatment alone increased the populations of aerobic bacteria, lactic acid bacteria, and yeasts and molds on the packaged slices during storage compared to those on corresponding control slices and resulted in extensive juice leakage from the slices. The ethylene treatment also resulted in high aerobic bacterial counts throughout the flesh of whole melons compared to the controls. Treating watermelons with 0.5 or 1.0 ppm 1-MCP prior to ethylene exposure counteracted the deleterious effects of ethylene. Extending the time from harvest to 1-MCP treatment increased the population of aerobic bacteria, but had no detectable effect on the growth of lactic acid bacteria or yeasts and molds. The results indicate that low concentrations (0.5 or 1.0 ppm) of 1-MCP can be used on whole watermelon to avoid deleterious effects of exogenous ethylene to which the melons could be exposed during shipping or storage.
    Journal of Food Science 07/2006; 71(6):M180 - M184. · 1.78 Impact Factor
  • Robert A. Saftner
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    ABSTRACT: The ethylene precursor, 1-aminocyclopropane-1-carboxylic acid (ACC), is actively transported across the tonoplast of plant cells, impacting cellular compartmentation of ACC and ethylene biosynthesis. In the present study, the effects of ACC and amino acid analogs on ACC uptake into isolated maize (Zea mays L. cv. Golden Cross Bantam) mesophyll vacuoles were investigated to identify the stereospecific and structural features that are important in molecular recognition by the ACC transport system. Of the four stereoisomers of l-amino-2-ethylcyclopropane-l-carboxylic acid (AEC), (1S, 2R)-(–)-AEC having a configuration corresponding to an L-amino acid was the preferred substrate for the ACC transport system, competitively inhibiting ACC transport with a Ki of 18 μM. Of 11 neutral amino acid stereoisomers, L-isomers were stronger inhibitors of ACC transport than corresponding D-isomers. Neutral L-amino acids with nonpolar side chains generally were more inhibitory than those with polar side chains, whereas several cationic and anionic L-amino acids were ineffective antagonists of ACC transport. These observations suggest that the ACC transport system is stereospecific for relatively nonpolar, neutral L-amino acids. This conclusion was supported by the observation that group additions, substitutions, or deletions at the carboxyl. -amino and the Pro- (R) methylene or hydrogen moieties (analogous to D-amino acids) of ACC and other neutral amino acids and analogs essentially eliminated transport inhibition. In contrast, L-amino acid analogs with variable substitutions at the distal end of the molecule remained antagonists. The relative activity of analogs was influenced by the length and degree of unsaturation of the side chain and by the location of side chain branching. Increasing the ring size of ACC analogs reduced antagonism whereas incorporating the -amino group into the ring structure as an L-amino acid increased antagonism. The kinetics of L-methoxyvinylglycine, L-methionine. p-nitro-L-phenylalanine and 1-aminocyclobutane-l-carboxylic acid were competitive with Ki values of 3, 13, 16 and 19 μM, respectively. These results indicate that the ACC transport system can be classifie as a neutral L-amino acid carrier having a relatively high affinity for ACC and other nonpolar amino acids. The results also suggest that the carrier interacts with the carboxyl, -amino and Pro-(R) groups and with other less restricted side chain substituents of substrate amino acids.
    Physiologia Plantarum 04/2006; 92(4):543 - 554. · 3.66 Impact Factor

Publication Stats

755 Citations
78.79 Total Impact Points

Institutions

  • 2005–2011
    • United States Department of Agriculture
      • Agricultural Research Service (ARS)
      Washington, D. C., DC, United States
  • 2003
    • University of the District of Columbia
      Washington, Washington, D.C., United States
  • 1990
    • Maryland Department Of Agriculture
      Annapolis, Maryland, United States