Community food security: Practice in need of theory?

Practitioners and advocates of community food security (CFS) envision food systems that are decentralized, environmentally-sound over a long time-frame, supportive of collective rather than only individual needs, effective in assuring equitable food access, and created by democratic decision-making. These themes are loosely connected in literature about CFS, with no logical linkages among them. Clear articulation in a theoretical framework is needed for CFS to be effective as a guide for policy and action. CFS theory should delimit the level of analysis (i.e., what are the boundaries of community); show how CFS relates to individual, household, and national food security and explain emergent properties, which are important at the community level of analysis; point to the best indicators of CFS or its lack; clarify the determinants of CFS; and clarify the stages of movement toward CFS. This theoretical base would allow researchers to develop valid and reliable measures, and allow practitioners to weigh alternative options to create strategic plans. A theoretical base also would help establish common ground with potential partners by making the connections to anti-hunger work, sustainable agriculture, and community development clear.     

Monitoring of moisture redistribution in multicomponent food systems by use of magnetic resonance imaging

Differences in water activity within multicomponent food systems inevitably lead to moisture (re)distribution phenomena, hence deteriorating textural quality during shelf life. Noninvasive assessment of moisture transport in such systems would promote mechanistic understanding and enable rational development of strategies to control migration. Magnetic resonance imaging (MRI) is an ideal candidate for such a measurement technique, but its use in systems with low-moisture components (e.g., cereal materials) is seriously hampered because of reduced transverse relaxation times. In this work, we report two MRI protocols for the noninvasive and quantitative assessment of moisture transport in multicomponent food products. The first protocol is suitable to study relatively slow (days/weeks) processes, whereas the second one is designed to study fast (hours) moisture transport. We have successfully applied this methodology to quantify moisture transport within multicomponent food systems, with adequate temporal and spatial resolution.     

Biosynthesis of 14C-phytoene from tomato cell suspension cultures (Lycopersicon esculentum) for utilization in prostate cancer cell culture studies

This work describes the development and utilization of a plant cell culture production approach to biosynthesize and radiolabel phytoene and phytofluene for prostate cancer cell culture studies. The herbicide norflurazon was added to established cell suspension cultures of tomato (Lycopersicon esculentum cv. VFNT cherry), to induce the biosynthesis and accumulation of the lycopene precursors, phytoene and phytofluene, in their natural isomeric forms (15-cis-phytoene and two cis-phytofluene isomers). Norflurazon concentrations, solvent carrier type and concentration, and duration of culture exposure to norflurazon were screened to optimize phytoene and phytofluene synthesis. Maximum yields of both phytoene and phytofluene were achieved after 7 days of treatment with 0.03 mg norflurazon/40 mL fresh medium, provided in 0.07% solvent carrier. Introduction of 14C-sucrose to the tomato cell culture medium enabled the production of 14C-labeled phytoene for subsequent prostate tumor cell uptake studies. In DU 145 prostate tumor cells, it was determined that 15-cis-phytoene and an oxidized product of phytoene were taken up and partially metabolized by the cells. The ability to biosynthesize, radiolabel, and isolate these carotenoids from tomato cell cultures is a novel, valuable methodology for further in vitro and in vivo investigations into the roles of phytoene and phytofluene in cancer chemoprevention.     

A simple high-performance liquid chromatography method for the determination of throat-burning oleocanthal with probated antiinflammatory activity in extra virgin olive oils

A high-performance liquid chromatography (HPLC) method was developed to quantitatively analyze oleocanthal in extra virgin olive oils. Oleocanthal, a deacetoxy ligstroside aglycone, is known to be responsible for the back of the throat irritation of olive oils and to have probated antiinflamatory activity. Oleocanthal was isolated from small amounts of olive oil sample (1 g) by liquid-liquid extraction. Hexane-acetonitrile was found to be the best solvent system to extract oleocanthal from the oil matrix. The solvent extract was analyzed by reversed-phase HPLC with UV detection at 278 nm. Chromatogaphic separation of oleocanthal from other extracted compounds and of the two geometric isomers of oleocanthal was achieved by an elution gradient with acetonitrile and water. Both the external standard calibration curve and the internal standard calibration curve were established, and quantitation using both calibration curves gave essentially the same result. The reproducibility (RSD = 4.7%), recovery (> 95%), and limit of quantitation (< 1 microg/g) were also determined. Concentrations of oleacanthal in 10 selected throat-burning extra virgin olive oils were determined using the method (ranged from 22 to 190 microg/g) with external standard calibration.     

Using Lidar to Measure Perfluorocarbon Tracers for the Verification and Monitoring of Cap and Cover Systems

Waste site cover systems used to prevent rainfall from reaching the waste need to remain intact throughout the lifetime of the waste site. Monitoring of these covers is needed to ascertain the performance and to determine if any degradation has occurred. Researchers at Brookhaven National Laboratory have used gaseous perfluorocarbon tracers (PFTs) to monitor the integrity of caps and covers for waste disposal sites. Detection of the PFTs currently uses gas chromatography techniques developed at BNL. This paper presents a potential approach to this wide-area screening problem by replacing conventional gas chromatography analysis with laser-based, lidar (Light Detection and Ranging) detection of the PFTs. Lidar can be used to scan the surface of the cover system, looking for fugitive PFTs. If successful this would enable the departure from soil gas analysis and instead look for PFTs in the air just above the soil surface. The advantages of using a lidar platform are multi-fold and include the elimination of soil monitoring ports. Benchtop and pilot-scale indoor experiments using an a continuous wave, line-tunable infrared CO₂ laser were used to detect PMCH (perfluoromethylcyclohexane, one of a group of PFTs used at BNL). Laboratory measurements of the absorption cross-section were the same order of magnitude compared to literature values for similar perfluorocarbon compounds. Initial benchtop, fixed cell length experiments were successful in detecting PMCH to levels of 10 ppb-m. To improve the lower limit of detection, a HgCdTe detector was purchased that was more specific to the lasing region of interest and hence had a higher sensitivity at this spectral region Using a pilot-scale lidar system in a 40m indoor hallway air concentrations of PMCH were then measured down to 1 ppb-m. These results are very promising and show great potential for monitoring the integrity of cover systems using lidar and PFTs.     

Density Dependent Grazing In Estuarine Water Quality Models

The objective of this study is to examine the influence different zooplankon grazing rate relationships have on water quality eutrophication model results in a tidal estuary. The water quality model being used includes phytoplankton and both dissolved and particulate constituents as state variables. It includes zooplankton grazing of the phytoplankton, where excretions from the latter increase the particulate constituents. The phytoplankton and particulate constituents also undergo settling. When applied to an existing estuary, the model results are different for a first order zooplankton grazing rate formulation than for a second order zooplankton grazing rate formulation.Constituents enter the estuary as wastewater discharges, freshwater river inflows, exchanges between the sediment and water interface, and exchange across the tidal boundary. The water quality model is coupled with a three-dimensional time varying hydrodynamic and transport model that allows accurate computation of the tidal velocity field transporting the constituents from their sources throughout the estuary. Comparisons of model results between the first order and the second order density dependent zooplankton grazing relationships allow determining which of the two processes best describe water quality behavior for the estuary being examined. The second order density dependent zooplankton grazing relationship performs best in application.     

Dialkylphosphates (DAPs) in fruits and vegetables may confound biomonitoring in organophosphorus insecticide exposure and risk assessment

Trace residues of organophosphorus (OP) pesticides are associated with fruits and vegetables that have been sprayed with those OP pesticides to guard against insect pests. Human dietary exposure to these OP pesticides is commonly estimated by measuring the amount of OP metabolites in urine, assuming a stoichiometric relationship between a metabolite and its parent insecticide. Dialkylphosphates (DAPs) are the OP metabolites that are most often used as markers in such biomonitoring studies. However, abiotic hydrolysis, photolysis, and plant metabolism can convert OP chemicals (OP residues) to DAP residues on or in the fruits and vegetables. To evaluate the extent of these conversions, OPs and DAPs were measured in 153 produce samples. These samples from 2 lots were known to contain OP insecticide residues based on routine monitoring by California producers and shippers. A total of 12 OPs were quantified, including mevinphos, naled, acephate, methamidophos, oxidemeton-methyl, azinphos-methyl, dimethoate, malathion, methidathion, phosmet, chlorpyrifos, and diazinon. All OP insecticide residues were below their respective residue tolerances in 2002-2004. A total of 91 of 153 samples (60%) contained more DAP residues than parent OPs. The mean mole fractions [DAPs/(DAPs + OPs)] for the first and second lots of produce were 0.62 and 0.50, respectively, and the corresponding geometric means were 0.55 and 0.34. The corresponding mean mole ratios (DAPs/OP) were 7.1 and 3.4, with geometric means of 2.1 and 0.9. Any preformed DAPs ingested in the diet that are excreted in urine may inflate the estimated absorbed OP insecticide doses in occupational and environmental studies. In subsequent prospective studies, time-dependent production of dimethylphosphate (DMP) and dimethylthiophosphate (DMTP) in strawberries and leaves following malathion sprays occurred concomitant with the disappearance of the parent insecticide and its oxon. DAPs are more persistent in plants and produce at routinely measured levels than their parent OP insecticides.     

Optimization of lycopene extraction from tomato cell suspension culture by response surface methodology

Radioisotope-labeled lycopene is an important tool for biomedical research but currently is not commercially available. A tomato cell suspension culture system for the production of radioisotope-labeled lycopene was previously developed in our laboratory. In the current study, the goal was to optimize the lycopene extraction efficiency from tomato cell cultures for preparatory high-performance liquid chromatography (HPLC) separation. We employed response surface methodology (RSM), which combines fractional factorial design and a second-degree polynomial model. Tomato cells were homogenized with ethanol, saponified by KOH, and extracted with hexane, and the lycopene content was analyzed by HPLC-PDA. We varied five factors at five levels: ethanol volume (1.33-4 mL/g); homogenization period (0-40 s/g); saturated KOH solution volume (0-0.67 mL/g); hexane volume (1.67-3 mL/g); and vortex period (5-25 s/g). Ridge analysis by SAS suggested that the optimal extraction procedure to extract 1 g of tomato cells was at 1.56 mL of ethanol, 28 s homogenization, 0.29 mL of KOH, 2.49 mL of hexane, and 17.5 s vortex. These optimal conditions predicted by RSM were confirmed to enhance lycopene yield from standardized tomato cell cultures by more than 3-fold.     

Simplified equations for the determination of the hydraulic properties of horticultural substrates by one‐step outflow experiments

Simplified algebraic equations are derived to calculate directly the Brooks and Corey model parameters using data obtained from one‐step outflow experiments and saturated hydraulic conductivity. The suggested method has been demonstrated only for horticultural substrates and is verified experimentally for four substrates with satisfactory agreement of the results.