[Show abstract][Hide abstract] ABSTRACT: Microgreens are an emerging food product with scarce information pertaining to their sensory and nutritional properties. In this study, six species of microgreens, including Dijon mustard (Brassica juncea L. Czern.), opal basil (Ocimum basilicum L.), bull's blood beet (Beta vulgaris L.), red amaranth (Amaranthus tricolor L.), peppercress (Lepidium bonariense L.) and China rose radish (Raphanus sativus L.), were evaluated for their sensory attributes and chemical compositions. Results showed that bull's blood beet had the highest rating on acceptability of flavor and overall eating quality while peppercress the lowest. Chemical compositions also differed significantly among the six species. China rose radish had the highest titratable acidity and total sugars, while red amaranth had the highest pH value and lowest total sugars. Regarding the phytonutrient concentrations, the highest concentrations of total ascorbic acid, phylloquinone, carotenoids, tocopherols, and total phenolics were found in China rose radish, opal basil, red amaranth, China rose radish, and opal basil, respectively. The relationships between sensory-sensory attributes and sensory-chemical compositions were further studied. It was found that overall eating quality of microgreens was best correlated with flavor score and microgreen's pH value and total phenolic content were strongly correlated with flavor attributes, e.g., sourness, astringency, and bitterness. In general, despite the differences among individual microgreens, all of the microgreens evaluated in this study demonstrated "good" to "excellent" consumer acceptance and nutritional quality.
Full-text · Article · Dec 2015 · Postharvest Biology and Technology
[Show abstract][Hide abstract] ABSTRACT: Blue mold decay occurs during long term storage of apples and is predominantly caused by Penicillium expansum Link. Apples harvested in 2010 were stored in a controlled atmosphere at a commercial Pennsylvania apple packing and storage facility, and were examined for occurrence of decay in May 2011. Several decayed apples from different cultivars, exhibiting blue mold symptoms with a sporulating fungus were collected. One isolate recovered from a decayed 'Golden Delicious' apple fruit was identified as P. carneum Frisvad. Genomic DNA was isolated, 800 bp of the 3′ end of the β-tubulin locus was amplified using gene specific primers and sequenced (4). The recovered nucleotide sequence (GenBank Accession No. JX127312) indicated 99% sequence identity with P. carneum strain IBT 3472 (GenBank Accession No. JF302650) (3). The P. carneum colonies strongly sporulated and had a blue green color on potato dextrose agar (PDA), Czapek yeast autolysate agar (CYA), malt extract agar (MEA), and yeast extract sucrose agar (YES) media at 25°C after 7 days. The colonies also had a beige color on plate reverse on CYA and YES media. The species tested positive for the production of alkaloids, as indicated by a violet reaction for the Ehrlich test, and grew on CYA at 30°C and on Czapek with 1,000 ppm propionic acid agar at 25°C; all of which are diagnostic characters of this species (2). The conidiophores were hyaline and tetraverticillate with a finely rough stipe. Conida were produced in long columns, blue green, globose, and averaged 2.9 μm in diameter. To prove pathogenicity, Koch's postulates were conducted using 20 'Golden Delicious' apple fruits. Fruits were washed, surface sterilized with 70% ethanol, and placed onto fruit trays. Using a nail, 3-mm wounds were created and inoculated with 50 μl of a 106/ml conidial suspension or water only as a negative control. The fruit trays were placed into boxes and were stored in the laboratory at 20°C for 7 days. The inoculated fruit developed soft watery lesions, with hard defined edges 37 ± 4 mm in diameter. The sporulating fungus was reisolated from infected tissue of all conidia inoculated apples and confirmed to be P. carneum by polymerase chain reaction (PCR) using the β-tubulin locus as described. Water inoculated control apples were symptomless. Originally grouped with P. roqueforti, P. carneum was reclassified in 1996 as a separate species (1). P. carneum is typically associated with meat products, beverages, and bread spoilage and produces patulin, which is not produced by P. roqueforti (1,2). Our isolate of P. carneum was susceptible to the thiabendazole (TBZ) fungicide at 250 ppm, which is below the recommended labeled application rate of 600 ppm. The susceptibility to TBZ suggests that this P. carneum isolate has been recently introduced because resistance to TBZ has evolved rapidly in P. expansum (4). To the best of our knowledge, P. carneum has not previously been described on apple, and this is the first report of P. carneum causing postharvest decay on apple fruits obtained from storage in Pennsylvania.
[Show abstract][Hide abstract] 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.
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.
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.
[Show abstract][Hide abstract] 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.
[Show abstract][Hide abstract] 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.
Full-text · Article · Aug 2012 · Journal of Food Composition and Analysis
[Show abstract][Hide abstract] 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.
Full-text · Article · Sep 2011 · Journal of Agricultural and Food Chemistry
[Show abstract][Hide abstract] ABSTRACT: With 3 figures and 4 tables
Penicillium 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.
[Show abstract][Hide abstract] 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.
No preview · Article · Apr 2011 · Genetic Resources and Crop Evolution
[Show abstract][Hide abstract] 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.
[Show abstract][Hide abstract] 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.
[Show abstract][Hide abstract] 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.
[Show abstract][Hide abstract] 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.
[Show abstract][Hide abstract] 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.
Full-text · Article · Mar 2009 · Postharvest Biology and Technology
[Show abstract][Hide abstract] 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.
Preview · Article · Oct 2008 · Journal of Food Science
[Show abstract][Hide abstract] 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.
[Show abstract][Hide abstract] 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.
[Show abstract][Hide abstract] 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.
Full-text · Article · May 2008 · Postharvest Biology and Technology
[Show abstract][Hide abstract] ABSTRACT: Incidences of foodborne outbreaks involving enterohemorrhagic Escherichia coli strains with mutations in a key regulatory gene, rpoS, have been reported. Incentives, if any, for losing this regulatory function are not clear since the RpoS regulator is required for the expression of several environmental stress tolerance genes. RpoS also positively regulates 2 of the 3 acid-resistance systems of E. coli under aerobic growth conditions and enables the pathogen to survive gastric acid challenge. We selected 7 enterohemorrhagic E. coli isolates, 6 of which are known to carry defective rpoS gene, and then analyzed resistance to synthetic gastric juice after the strains were inoculated on fresh-cut lettuce and stored under modified atmosphere packaging (MAP) conditions. Subatmospheric oxygen partial pressures in MAP enabled all 6 rpoS-defective isolates to induce acid resistance over the 8-d storage period if the temperature was >or= 15 degrees C. No acid resistance was induced for MAP-stored lettuce left at temperatures <or= 10 degrees C or for lettuce packed and stored under aerobic conditions. The data underscore the impending danger of abusive storage temperatures especially with regard to the application of MAP to extend the shelf life of fresh produce. The results also highlight the biological significance of having multiple acid-resistance pathways and the complex regulatory network of enterohemorrhagic E. coli strains.
Preview · Article · May 2008 · Journal of Food Science