A comparison of wet-dry swabbing and excision sampling methods for microbiological testing of bovine, porcine, and ovine carcasses at red meat slaughterhouses

A comparison of wet-dry swabbing and surface tissue excision of carcasses by coring was undertaken. Samples from 1,352 bovine, 188 ovine, and 176 porcine carcasses were collected from 70 separate visits to commercial slaughterhouses operating under normal conditions. The mean total aerobic viable bacterial counts (TVCs) for all species sampled by excision was 5.36 log units, which was significantly greater than the 4.35 log units measured for swabbing. Poorly correlated linear relationships between swab- and excision-derived bacterial numbers from near-adjacent carcasses were observed for all three animal species. R2 values for least squares regressions for bovine, ovine, and porcine carcasses were 0.09, 0.27, and 0.21, respectively. The reasons why it was not possible to calculate a factor that allowed the interconversion of bacterial numbers between samples collected by each sampling method were investigated. Uncertainty associated with laboratory analyses was a contributing factor because the geometric relative standard deviations measured for TVCs were 0.174 and 0.414 for excision and swabbing, respectively. Uneven distribution of bacteria at identical sampling sites on near-adjacent carcasses on processing lines was also a contributory factor. The implications of these findings for process control verification were investigated by intensive sampling for 13 weeks in three commercial slaughterhouses. As many as 4 log units of difference in TVCs were observed in duplicate samples collected within a narrow timeframe from near-adjacent carcasses on the processing line. We conclude that it might not be appropriate to institute corrective actions in slaughterhouses on the basis of a single week's test results.     

Consumer home refrigeration practices: results of a web-based survey

To reduce bacterial growth and to ensure the quality and safety of food products, the U.S. Department of Agriculture and the U.S. Food and Drug Administration advise consumers to clean their refrigerators regularly, use a refrigerator thermometer, and keep refrigerator temperatures at 40 degrees F (4.4 degrees C) or below. We conducted a nationally representative Web-enabled survey (n = 2,060) to collect data on refrigerator thermometer ownership, home refrigerator temperatures, and the frequency of home refrigerator cleaning. We stratified the sample to provide results for pregnant women, older adults (60 years or older), and the remaining population. About half of all respondents had cleaned their refrigerators at least 1 month before the survey. Only 11% of all respondents had a thermometer in their refrigerator before the survey. Older adults (77.5%) were more likely than the remaining population (70.4%) to have their refrigerators at the recommended temperature (P < 0.01). Older adults who were not married and who lived alone were less likely to have refrigerator thermometers and to have their refrigerators at a recommended temperature (P < 0.05). For all respondents, those who had previously owned a refrigerator thermometer were more likely to have their refrigerators at the recommended temperature than were respondents who did not previously own a thermometer (P < 0.01). Food safety educators can use the survey findings and results of previous research to target educational materials and help consumers, especially those at risk for listeriosis, to safely store refrigerated foods at home.     

Comparison of Tomatillo and Tomato Volatile Compounds in the Headspace by Selected Ion Flow Tube Mass Spectrometry (SIFT-MS)

ABSTRACT: The concentration of 31 volatiles were measured in the headspace of tomatillos using selected ion flow tube-mass spectrometry (SIFT-MS), and were compared with those in vine-ripened tomato, roma tomato, cherry tomato, and grape tomato. None of the volatiles were higher in the headspace of tomatillos than of tomatoes. Compounds (E)-2-octenal, (E)-2-pentenal, 2-isobutylthiazole, 6-methyl-5-hepten-2-one, and phenylacetaldehyde were significantly lower in tomatillo than in the tomato varieties in the headspace. After blending, volatiles in the headspace increased, and then decreased after reaching a maximum concentration, due to further degradation or depletion. Compounds (E)-2-pentenal and 1-penten-3-one reached a maximum concentration later than (E)-2-hexenal, (Z)-3-hexenal, and hexanal for tomatillo and tomatoes. The slope of the ratio of (E)-2-hexenal and (Z)-3-hexenal was not significantly different for any of the samples, implying that the activity of cis/trans isomerase was not different between tomatillos and tomatoes.     

An application of meta-analysis in food safety consumer research to evaluate consumer behaviors and practices

Meta-analysis provides a structured method for combining results from several studies and accounting for and differentiating between study variables. Numerous food safety consumer research studies often focus on specific behaviors among different subpopulations but fail to provide a holistic picture of consumer behavior. Combining information from several studies provides a broader understanding of differences and trends among demographic subpopulations, and thus, helps in developing effective risk communication messages. In the illustrated example, raw/undercooked ground beef consumption and hygienic practices were evaluated according to gender, ethnicity, and age. Percentages of people engaging in each of the above behaviors (referred to as effect sizes) were combined using weighted averages of these percentages. Several measures, including sampling errors, random variance between studies, sample sizes of studies, and homogeneity of findings across studies, were used in the meta-analysis. The statistical significance of differences in behaviors across demographic segments was evaluated using analysis of variance. The meta-analysis identified considerable variability in effect sizes for raw/undercooked ground beef consumption and poor hygienic practices. More males, African Americans, and adults between 30 and 54 years (mid-age) consumed raw/undercooked ground beef than other demographic segments. Males, Caucasians, and Hispanics and young adults between 18 and 29 years were more likely to engage in poor hygienic practices. Compared to traditional qualitative review methods, meta-analysis quantitatively accounts for interstudy differences, allows greater consideration of data from studies with smaller sample sizes, and offers ease of analysis as newer data become available, and thus, merits consideration for its application in food safety consumer research.     

Can sequential harvesting help small holder organic farmers meet consumer expectations for organic potatoes?

The effectiveness of sequential harvesting in ensuring that potatoes produced by small-scale organic farmers in Embo, KwaZulu-Natal, South Africa, meet consumer quality expectations was investigated. A survey of organic and conventional potato consumers showed that absence of greening, sprouting and blemishes and a smooth skin texture were the criteria used by the consumers in selecting potatoes to purchase. Most consumers expected potatoes to store for three weeks post purchase. Based on consumer quality expectations, significantly higher quality losses were noted when potatoes were stored in a farmer’s store compared to sequential harvesting. After six weeks from crop maturity, sequential harvesting significantly reduced potato post harvest dormancy period but did not negatively affect sensory acceptability. Sequentially harvested potatoes met consumer quality and storage expectations. The practice provides resource-poor small-scale organic farmers with an efficient storage option where other methods and technologies may be inappropriate, ineffective or unaffordable.     

Effect of powder and target properties on wrap around effect during coating

Tapioca starch, NaCl (28, 135, and 378 μm), corn starch, cocoa powder, soy protein isolate, cheese powder, wheat protein, modified starch, nacho cheese, and sugar were coated at 0 kV for nonelectrostatic and at 25 kV for electrostatic coating onto metal, wood, unoiled paper, oiled paper, unoiled plastic, oiled plastic, fresh bread, and dry bread. Powders and targets were allowed to naturally tribocharge, or all charge was removed before coating. Powder particle size, flowability, resistivity, and target resistivity were reported. Electrostatic coating produced the same or better wrap around, or percent side coverage as nonelectrostatic coating for every powder and target. The greatest electrostatic improvement was found when using powders that had the worst nonelectrostatic side coverage: large particle size (>135 μm), low resistivity, and low cohesiveness, especially on targets that had high-surface resistivity (2 × 10(5) Ωm). Tribocharging had a similar effect as electrostatic coating. In both nonelectrostatic and electrostatic coating, percent side coverage increased as powder particle size decreased, cohesiveness increased, or target resistivity decreased. In electrostatic coating, percent side coverage increased as powder resistivity increased; however, in nonelectrostatic coating, as powder resistivity increased, percent side coverage increased on only oiled plastic and dry bread. Practical Application: The evenness of powder coating on food is very important for consumer acceptability, since consumers judge food from its appearance before they have a chance to taste it. If thick food targets, such as cakes, donuts, and marshmallows need to be coated, the side coverage, due to the wrap around effect, is important. Choosing powders with small particle size, high cohesiveness and high-powder resistivity, and using electrostatic coating can produce food targets coated on all sides.     

Improving Adhesion of Seasonings to Crackers with Hydrocolloid Solutions

Food powders were applied on crackers that had been coated using water, oil, emulsion, sucrose, or hydrocolloid solutions. The hydrocolloids that were used include gellan gum, kappa‐carrageenan, methylcellulose, gum karaya, gum tragacanth, gum arabic, guar gum, modified starch, and maltodextrin. Solutions of similar hydrophobicity to the powder gave the greatest adhesion. NaCl, barbecue (BBQ), ranch, and sour cream & onion (SC&O) seasoning showed greatest adhesion with water, cheese powder with an emulsion of 12.5% to 25% oil, and cocoa powder with oil. For NaCl, BBQ, ranch, and SC&O seasoning, hydrocolloids improved the adhesion over using water alone, with gellan gum providing the greatest adhesion. Hydrocolloid structural differences, including the presence or absence of branching, substitution of sugar units, and molecular weight affect water binding and thickening of the hydrocolloid spray that seemed to be significant factors affecting adhesion of powders to the target surface. For cheese powder, hydrocolloids were capable of replacing the oil within an emulsion while improving or maintaining the same level of adhesion, with gum arabic providing the greatest adhesion. For cocoa powder, hydrocolloid solutions were ineffective adhesives due to differences in hydrophilicity that result in insolubility. The effect of hydrocolloid concentration on adhesion was dependent both on the hydrocolloid type and the concentration that is sprayable, with 0.5% being the optimum concentration for most gums. Adhesion using sucrose solutions was determined by particle size and relative hydrophobicity. Increasing sucrose concentration decreased adhesion of smaller particles, but increased adhesion of larger particles. Adhesion of NaCl significantly increased with decreasing NaCl size using oil, water, and sucrose solutions.     

Copper oxide photocathodes prepared by a solution based process

Solution based processes are well known by their low-cost trait to fabricate semiconductor devices. In this study, we devised an economical solution based route to photoelectrochemical (PEC) cells, taking copper nitrate as the copper ion source and adding an alkali hydroxide, here NaOH, to produce high aspect ratio (3.1–9.7) CuO nanoparticles. These CuO particles were used for splitting water and generation of hydrogen via a PEC cell. CuO nanoparticle morphology, i.e. rod-like, spindle-like, and needle-like, was dependent on the processing temperature. Sintering the spin coated CuO films, improved crystallinity. The bandgaps for these films were estimated to be 1.35 eV and 1.64 eV for sintering temperatures of 600 °C and 400 °C for 1 h, respectively. The porous structure of the nano-sized CuO films increased surface area and thus led to a high photocurrent, i.e. 1.20 mA/cm², for powder prepared at 60 °C and sintered at 600 °C for 1 h. These films demonstrated 0.91% solar conversion efficiency at an applied voltage of −0.55 V vs. Ag/AgCl in 1 M KOH electrolyte with 1 sun (AM1.5G) illumination. The charge carrier density was estimated to be 6.1 × 10²⁰ cm⁻³. This relatively high charge carrier density may be due to the high surface area and short transport distance to the electrode/electrolyte interface in the porous nanostructure.     

Evidence of enantioselective degradation of alpha-hexachlorocyclohexane in groundwater

In the fall of 2000, 34 groundwater samples were collected from beneath an active pesticide reformulating and packaging facility in coastal northeastern Florida to measure the enantiomer fractions (EFs) of alpha-hexachlorocyclohexane (alpha-HCH) as an indicator of biodegradation of this chlorinated pesticide in groundwater. Concentrations of alpha-HCH as high as 500 microg/L were observed beneath the historical source area and decreased with distance downgradient. Seventy-eight percent of the EF values were greater than 0.504 and ranged up to 0.890, indicating that the (-)-alpha-HCH enantiomer is preferentially degraded relative to the (+)-alpha-HCH enantiomer at this site. Samples taken from the groundwater that flows north from the historical disposal facility to a local discharge point at a creek did not indicate enantioselective degradation (EF values ranged from 0.495 to 0.512). The acidity (pH 3.7-4.6) and short flow path to the creek for this lobe of the groundwater plume likely preclude biodegradation of alpha-HCH. In contrast, the neutral lobe of the groundwater plume, which flows eastward from the historical source area, demonstrated enantioselective degradation (EF values ranged from 0.500 to 0.890 and increased with distance from the source area). Groundwater conditions beneath this portion of the site are conducive to biodegradation of HCH owing to anaerobic reducing conditions and lengthy travel times, and the chiral signatures for alpha-HCH provide evidence that biological degradation is occurring beneath this portion of the site.     

Radiocarbon evidence for a naturally produced, bioaccumulating halogenated organic compound

Halogenated organic compounds (HOCs) such as 1,1'-dimethyl-3,3',4,4'-tetrabromo-5,5'-dichloro-2,2'-bipyrrole (DBP-Br4Cl2) and heptachloro-1'-methyl-1,2'-bipyrrole (Q1) have been detected worldwide, sometimes at high levels in Antarctic air, seabird eggs, the blubber of marine mammals, and, most notably, even human milk. To date, it has been difficult to determine whether these compounds are natural products or derived from industrial synthesis. Molecular-level 14C analysis of these compounds is particularly appealing because most industrial compounds are manufactured from petrochemicals (14C-free) and natural compounds should have "modern" or "contemporary" 14C levels. To investigate the source of DBP-Br4Cl2, we isolated 600 microg of this compound (150 microg of carbon) from marine animal extracts by employing gel permeation chromatography, Florisil column chromatography, and two-dimensional preparative capillary gas chromatography. The purified DBP-Br4Cl2 was split into two samples (75 microg of carbon each) and analyzed by accelerator mass spectrometry for 14C content. The delta14C values were -449 percent per thousand and -467 percent per thousand, corresponding to conventional 14C ages of 4740 and 5000 years before present (BP), respectively. The presence of detectable 14C in the DBP-Br4Cl2 strongly points to at least a natural or biogenic source. However, these delta14C values for DBP-Br4Cl2 are more depleted than expected for a recently synthesized natural product. Several explanations are discussed, but additional samples