Sensory and Physicochemical Quality, Residual Fungicide Levels and Microbial Load in 'Florida Radiance' Strawberries from Different Disease Control Treatments Exposed to Simulated Supply Chain Conditions.

Strawberries are greatly appreciated for their flavor and health-promoting properties. However, current agricultural and postharvest handling practices may result in decreased fruit quality. The objective of this work was to determine the effect of conventional or reduced fungicide applications on the quality of 'Florida Radiance' strawberries exposed to supply chain conditions. Strawberries held under steady temperature had better sensory and physicochemical quality than fruit exposed to supply chain conditions, regardless of the disease control treatment. Strawberries from the reduced fungicide treatment were firmer, lost less moisture, had higher sugar and higher or similar bioactive contents than fruit from the conventional treatment. Sensory scores were better for reduced fungicide fruit held under steady temperature conditions than other treatments at the consumer level. Microbial load increased during the supply chain but results strongly suggest that washing the fruit significantly reduces the microbial load and residual fungicide levels (fludioxonil, cyprodinil, pyraclostrobin, and captan) on the fruit. Overall, the use of reduced fungicide applications to control strawberry disease constitutes a promising alternative to conventional practices. It will help reduce costs by reducing labor and the amount of fungicides used while maintaining overall strawberry quality. Moreover, avoiding abusive and fluctuating temperature conditions during the supply chain will extend shelf-life and reduce strawberry waste.

Sensory Quality, Physicochemical Attributes, Polyphenol Profiles, and Residual Fungicides in Strawberries from Different Disease-Control Treatments.

Using alternative agricultural practices in combination with proper postharvest handling has become a major goal to improve fresh produce quality. Here, two different strawberry ( Fragaria × ananassa) genotypes were used as a model to study the impact of repeated, reduced-fungicide or no-fungicide applications on the sensory quality, physicochemical attributes, polyphenol profiles, and residual fungicide in strawberries. Strawberries grown under reduced-fungicide applications had similar or better physicochemical quality than conventionally and organically grown fruit and lower levels of fungicide residues than conventional fruit. Overall, flavor- and health-related attributes of strawberries from reduced-fungicide applications were intermediate between conventional and organic fruit. Thus, growing strawberries with reduced-fungicide applications can be an alternative to conventional or organic agricultural practices.

Imidacloprid Extraction from Citrus Leaves and Analysis by Liquid Chromatography-Mass Spectrometry (HPLC-MS/MS).

A procedure was developed to extract Imidacloprid (IMD) from newly-flushed and fully-expanded citrus leaves. The extraction was conducted in a bullet blender, using a small sample mass (0.5 g of fresh tissue), stainless-steel beads (24 g), and methanol as extractant (10 mL). The extracts did not require further clean-up before analysis by HPLC-MS/MS. The method was validated with control samples from IMD-untreated Hamlin orange trees. The method limit of detection and limit of quantitation were 0.04 and 0.12 µg g(-1), respectively. IMD recoveries from fortified leaf tissue were between 92 % and 102 %, with relative standard deviations of <8 %. The method was further evaluated by extracting leaves from Hamlin orange trees treated with IMD. The treated trees showed maximum concentrations of 10.8 and 21.8 µg g(-1), observed at 20 days after applying two soil-drenching rates (0.51 and 1.02 kg IMD ha(-1)), respectively. This extraction technique will generate useful data on IMD plant uptake, foliar concentration, and correlations with Asian citrus psyllid (ACP) mortality or control. The method could be used to generate baseline data to improve IMD soil-drenching applications as the main management practice to control the ACP.

Enzyme release of phenolics from muscadine grape (Vitis rotundifolia Michx.) skins and seeds.

Enzyme degradation of plant cell wall polysaccharides can potentially enhance the release of bioactive phenolics. The aim of this study was to evaluate various combinations of solvent and enzyme, enzyme type (cellulase, pectinase, ß-glucosidase), and hydrolysis time (1, 4, 8, 24 h) on the release of muscadine grape skin and seed phenolics, and their antioxidant activities. Results showed that pre-treated muscadine skins and seeds with enzymes decreased total phenolic yield compared with solvent (50% ethanol) alone. Enzyme release of phenolics from skins of different muscadine varieties was significantly different while release from seeds was similar. Enzyme hydrolysis was found to shorten extraction time. Most importantly, enzyme hydrolysis modified the galloylated form of polyphenols to low molecular weight phenolics, releasing phenolic acids (especially gallic acid), and enhancing antioxidant activity.

Peanut Allergy, Peanut Allergens, and Methods for the Detection of Peanut Contamination in Food Products.

Attention to peanut allergy has been rising rapidly for the last 5 y, because it accounts for the majority of severe food-related anaphylaxis, it tends to appear early in life, and it usually is not resolved. Low milligram amounts of peanut allergens can induce severe allergic reactions in highly sensitized individuals, and no cure is available for peanut allergy. This review presents updated information on peanut allergy, peanut allergens (Ara h1 to h8), and available methods for detecting peanuts in foods. These methods are based on the detection of either peanut proteins or a specific DNA fragment of peanut allergens. A summary of published methods for detecting peanut in foods is given with a comparison of assay formats, target analyte, and assay sensitivity. Moreover, a summary of the current availability of commercial peanut allergen kits is presented with information about assay format, target analyte, sensitivity, testing time, company/kit name, and AOAC validation.

Investigation of NeutrAvidin-tagged liposomal nanovesicles as universal detection reagents for bioanalytical assays.

Ligand-tagged liposomes, obtained by covalent conjugation of ligands to the liposomal surface, have been widely used as detection reagents in bioanalytical assays. A non-covalent conjugation method where IgG was attached to protein G-tagged liposomes has been recently utilized. To enlarge the application of non-covalent methods to a greater variety of ligands, including peptides, proteins, and nucleic acids, we developed and optimized a new method for the preparation of NeutrAvidin-tagged liposomes with subsequent attachment of biotinylated ligands. Two assays were used to investigate the feasibility of NeutrAvidin-tagged liposomes. The first assay was a competitive immunoassay for detecting rabbit antibodies, while the second assay was a sandwich hybridization assay for detecting a synthetic target: a DNA fragment of Erwinia amylovora. To produce the immunoliposomes for the detection of rabbit IgG, NeutrAvidin was covalently tagged to the liposomal surface at four different starting molar percentages (0.1, 0.2, 0.4, and 0.8). The biotinylated goat anti-rabbit IgG at three different molar ratios of biotin to IgG (5, 10, and 20) were then attached to the NeutrAvidin-tagged liposomes by using two different molar ratios of goat anti-rabbit IgG to NeutrAvidin (1 and 5). After the comparison of all 24 combinations, the best result was obtained with the 0.1 starting molar percentage of NeutrAvidin, 20 as the molar ratio of biotin to goat IgG, and 1 as molar ratio of IgG to NeutrAvidin. Under these optimized conditions, the limit of detection (LOD) for rabbit IgG was 38pmol/mL. Moreover, the best combination for the sandwich hybridization assay was with the 0.1 starting molar percentage of NeutrAvidin-tagged liposomes and when the molar ratio of biotinylated reporter probe to NeutrAvidin was equal to 1. The LOD for the synthetic target DNA fragment of E. amylovora was ca. 30pmol/mL. Both assays could be completed in about 30min without the requirement of sophisticated equipment or techniques. Therefore, these two assays have successfully demonstrated the feasibility of NeutrAvidin-tagged liposomal nanovesicles as a universal reagent for the attachment of different types of biotinylated ligands in a fast and easy coupling process. In addition, these ligand-tagged liposomes have the potential for wide use in different types of bioanalytical assays.

Development of a competitive liposome-based lateral flow assay for the rapid detection of the allergenic peanut protein Ara h1.

A competitive lateral flow assay for detecting the major peanut allergen, Ara h1, has been developed. The detector reagents are Ara h1-tagged liposomes, and the capture reagents are anti-Ara h1 polyclonal antibodies. Two types of rabbit polyclonal antibodies were raised either against the entire Ara h1 molecules (anti-Ara h1 Ab) or against an immunodominant epitope on Ara h1 (anti-peptide Ab). All of them reacted specifically with Ara h1 in Western Blot against crude peanut proteins. Moreover, the anti-Ara h1 Ab was chosen for this assay development because of its highest immunoactivity to Ara h1-tagged liposomes in the lateral flow assay. The calculated limit of detection (LOD) of this assay is 0.45 microg mL(-1) of Ara h1 with a dynamic range between 0.1 and 10 microg mL(-1) of Ara h1 in buffer. Additionally, the visually determined detection range is from 1 to 10 microg mL(-1) of Ara h1 in buffer. Results using this assay can be obtained within 30 min without the need of sophisticated equipment or techniques; therefore, this lateral flow assay has the potential to be a cost-effective, fast, simple, and sensitive method for on-site screening of peanut allergens.

Pisatin metabolism in pea (Pisum sativum L.) cell suspension cultures.

Cell suspension cultures were established from germinating pea (Pisum sativum L.) seeds. This cell culture, which accumulated pisatin, consisted mostly of single cells containing a few cell aggregates. The cells responded to treatment with a yeast glucan preparation with transient accumulation of pisatin in both cells and culture media. Addition of pisatin to cell cultures resulted in increased synthesis of pisatin. Phenylalanine ammonia-lyase, chalcone synthase and isoflavone reductase activities were present in untreated cells. Upon treatment with an elicitor preparation the activities of the first two enzymes showed a rapid, transient increase up to 20 hours after treatment. Isoflavone reductase showed a major and minor peak at 16 and 36 h, respectively, after elicitor treatment. The time course of the enzyme activity and pisatin accumulation is consistent with an elicitor-mediated response.