Effects of Rigor Status during High‐Pressure Processing on the Physical Qualities of Farm‐Raised Abalone (Haliotis rufescens)

High‐pressure processing (HPP) is used to increase meat safety and shelf‐life, with conflicting quality effects depending on rigor status during HPP. In the seafood industry, HPP is used to shuck and pasteurize oysters, but its use on abalones has only been minimally evaluated and the effect of rigor status during HPP on abalone quality has not been reported. Farm‐raised abalones (Haliotis rufescens) were divided into 12 HPP treatments and 1 unprocessed control treatment. Treatments were processed pre‐rigor or post‐rigor at 2 pressures (100 and 300 MPa) and 3 processing times (1, 3, and 5 min). The control was analyzed post‐rigor. Uniform plugs were cut from adductor and foot meat for texture profile analysis, shear force, and color analysis. Subsamples were used for scanning electron microscopy of muscle ultrastructure. Texture profile analysis revealed that post‐rigor processed abalone was significantly (P < 0.05) less firm and chewy than pre‐rigor processed irrespective of muscle type, processing time, or pressure. L values increased with pressure to 68.9 at 300 MPa for pre‐rigor processed foot, 73.8 for post‐rigor processed foot, 90.9 for pre‐rigor processed adductor, and 89.0 for post‐rigor processed adductor. Scanning electron microscopy images showed fraying of collagen fibers in processed adductor, but did not show pressure‐induced compaction of the foot myofibrils. Post‐rigor processed abalone meat was more tender than pre‐rigor processed meat, and post‐rigor processed foot meat was lighter in color than pre‐rigor processed foot meat, suggesting that waiting for rigor to resolve prior to processing abalones may improve consumer perceptions of quality and market value.     

Using the Essential Oil of Aloysia triphylla (L'Her.) Britton to Sedate Silver Catfish (Rhamdia quelen) during Transport Improved the Chemical and Sensory Qualities of the Fish during Storage in Ice

Exposure of silver catfish to 40 μL/L of the essential oil of Aloysia triphylla (AT) during in vivo transport delayed the onset and resolution of rigor mortis as well as the degradation of IMP into HxR compared to the control. The fish that were treated with 30 or 40 μL/L of AT received lower sensory demerit scores after 10 d of storage in ice compared to the control, and the fish that were treated with 40 μL/L of AT had a longer sensory shelf life than did the control. These results indicated that using AT as a sedative in the water in which the silver catfish were transported extended their freshness and increased their shelf life during refrigerated storage.     

Geography and stage of development affect persistent organic pollutants in stranded and wild-caught harbor seal pups from central California

Persistent organic pollutants have been associated with disease susceptibility and decreased immunity in marine mammals. Concentrations of polychlorinated biphenyls (PCBs), dichlorodiphenyltrichloroethane and its metabolites (DDTs), polybrominated diphenyl ethers (PBDEs), chlordanes (CHLDs), and hexachlorocyclohexane isomers (HCHs) were evaluated in terms of stage of development and likely exposure routes (in utero, suckling, fasting) in the blubber of 202 stranded and wild-caught, primarily young of the year (n = 177), harbor seals (Phoca vitulina) in the central California coast. This is the first report of HCH concentrations in the blubber of California seals. Lipid normalized concentrations ranged from 200 to 330,000 ng/g for sum PCBs, 320-1,500,000 ng/g for sum DDTs, 23-63,000 ng/g for sum PBDEs, 29-29,000 ng/g for sum CHLDs, and 2-780 ng/g for sum HCHs. The highest concentrations were observed in harbor seal pups that suckled in the wild and then lost mass during the post-weaning fast. Among the pups sampled in the wild and those released from rehabilitation, there were no differences in mass, blubber depth, or percent lipid although contaminant concentrations were significantly higher in the pups which nursed in the wild. When geographic differences were evaluated in a subset of newborn animals collected near their birth locations, the ratio of sum DDTs to sum PCBs was significantly greater in samples from an area with agricultural inputs (Monterey), than one with industrial inputs (San Francisco Bay). A principal components analysis distinguished between seals from San Francisco Bay and Monterey Bay based on specific PCB and PBDE congeners and DDT metabolites. These data illustrate the important influence of life stage, nutritional status, and location on blubber contaminant levels, and thus the need to consider these factors when interpreting single sample measurements in marine mammals.     

Microbiology of raw milk in New Zealand

The results of this study demonstrate the occurrence of the non-spore-forming pathogens, Staphylococcus aureus, Escherichia coli (total count and O157:H7), Listeria, Campylobacter and Salmonella, in New Zealand's raw milk supply. Samples of raw milk were collected monthly within five major dairying regions over one year. Each month, samples from five randomly selected farm vats in each region were collected for analysis (297 samples in total). Methods based on plate count techniques were used to enumerate S. aureus and E. coli. Enrichment methods in combination with a modified most probable number detection method were used to monitor samples for the presence of E. coli O157:H7, Listeria, Campylobacter and Salmonella. Salmonella was not detected in this study, and Campylobacter was isolated once (0.34%). E. coli was present at <100 cfu/ml in 99% of samples and exceeded 10(3)cfu/ml in 0.7% of samples. E. coli O157:H7 was not detected whereas non-pathogenic E. coli O157 strains (i.e. lacking genes for stx1, stx2, eae and Hly A) were detected in 1% of samples. S. aureus was not detected (<1 cfu/ml) in 21% of samples; levels were >1 but <100 cfu/ml in 60% of samples and on one occasion (0.34%) S. aureus exceeded 10(4)cfu/ml. L. monocytogenes was isolated from 0.68% of samples and L. innocua was present in 4% of samples. The results demonstrate that raw milk sampled from farm vats in New Zealand, as in other countries, inevitably contains recognised pathogens and, hence, control by pasteurisation or an equivalent treatment of raw milk remains paramount. Even so, the prevalence of most of these pathogens was lower than those reported in many of the studies performed in other countries.     

Fluorescent N2,N3-epsilon-adenine nucleoside and nucleotide probes: synthesis, spectroscopic properties, and biochemical evaluation

N1,N(6)-ethenoadenine, epsilon-A, nucleos(t)ides have been previously applied as fluorescent probes in numerous biochemical systems. However, these epsilon-A analogues lack the H-bonding capability of adenine. To improve the fluorescence characteristics while preserving the H-bonding pattern required for molecular recognition, we designed a novel probe: N(2),N3-etheno-adenosine, (N(2),N3-epsilon-A). Here, we describe four novel syntheses of the target epsilon-nucleoside and related analogues. These methods are short, facile, and provide the product regiospecifically. In addition, we report the absorption and emission spectra of N(2),N3-epsilon-A and the dependence of the spectral features on the pH and polarity of the medium. Specifically, maximum emission of N(2),N3-epsilon-A in water is observed at 420 nm (phi=0.03, excitation at 290 nm). The biochemical relevance of the new probe was evaluated with respect to the P2Y(1) receptor and NTPDases 1 and 2. N(2),N3-epsilon-ATP was found to be almost equipotent with ATP at the P2Y(1) receptor and was hydrolyzed by NTPDases 1 and 2 at about 80 % of the rate of ATP. Furthermore, protein binding does not seem to shift the fluorescence of N(2),N3-epsilon-ATP. Based on the fluorescence and full recognition by ATP-binding proteins, we propose N(2),N3-epsilon-ATP and related nucleo(s)tides as unique probes for the investigation of adenine nucleo(s)tide-binding proteins as well as for other biochemical applications.     

Milk thickeners do not influence anthropometric indices in childhood

BACKGROUND: Pediatric obesity is an important risk factor for chronic diseases in adulthood. Some infant feeding practices may contribute to childhood obesity. OBJECTIVE: To investigate whether the introduction of milk thickeners to bottle-fed infants between 3 and 6 months of age was associated with higher anthropometric measurements and indices at 1 and 4 years of age. METHODS: A population-based birth cohort study was conducted in 1993 in the urban area of Pelotas, Brazil. Information was obtained at birth, at 1, 3, 6, and 12 months, and at 4 years. Data were analyzed from the 596 children for whom information was available from all follow-up visits. The exposure of interest was the use of milk thickener (flour added to cow's milk) between the third and sixth months of life. The outcomes investigated were weight and length/height and the anthropometric indices weight-for-age, length/height-for-age, and weight-for-length/height z-scores at 1 and 4 years. RESULTS: The prevalence of use of milk thickener at any time between the third and sixth months was 44.6%. In the adjusted analysis, children who received milk thickener were, on average, 160 g heavier and 0.5 cm longer at I year than those who did not receive it. Weight-for-age and length-for-age z-scores were positively associated with use of milk thickener. No association was observed between this feeding practice and weight-for-length z-score. In the adjusted analysis, no effect of use of milk thickener on any of the anthropometric outcomes studied was observed at 4 years. CONCLUSIONS: No association was found between the use of milk thickeners and weight-for-length/height z-scores in the first and fourth years of life. Future studies in other contexts would be helpful to further test this hypothesis.     

Application of ozone sprays as a strategy to improve the microbial safety and quality of salmon fillets

Ozone research investigating the efficacy of spray application mechanisms for balancing microbial safety with chemical quality attributes of high lipid content fish is lacking. The objectives of this study were to investigate the influence of aqueous spray treatments of 1 mg/L and 1.5 mg/L ozone on the microbial and chemical quality indices of Atlantic salmon fillets inoculated with Listeria innocua as a surrogate species replacing the pathogen Listeria monocytogenes. In order to simulate industry processing parameters, number of passes under spray nozzles (1, 2, and 3) was also investigated.Listeria counts resulting from treatment with three passes of 1 mg/L ozone sprays were significantly lower (p ≤ 0.05) than non-ozonated controls on days 0, 3, 6, and 10 of refrigerated storage at 4 °C. At both ozone concentrations, Listeria counts were significantly influenced (p ≤ 0.05) by the number of passes under spray nozzles with increasing passes resulting in increasing reductions. The residual antimicrobial effectiveness of ozone at both concentrations against aerobic bacterial populations on treated samples was limited to <6 days storage at 4 °C. Lipid oxidation analyses indicate that ozone concentration did not significantly affect (p ≤ 0.05) TBARS but did influence headspace propanal with 1 mg/L ozone treatments yielding approximately 30% higher propanal values than spray treatments of 1.5 mg/L ozone. Both TBARS and propanal levels were significantly influenced (p ≤ 0.05) by storage time, yet the number of spray passes did not significantly affect either measure of lipid oxidation. Our results indicate that ozone sprays at concentrations up to 1.5 mg/L are effective in reducing initial counts of aerobic bacterial populations and in significantly reducing (p ≤ 0.05) counts of L. innocua without causing significant increases in lipid oxidation levels in farmed Atlantic salmon fillets during refrigerated storage at 4 °C.     

Oxidative stability and consumer acceptance of fish oil fortified nutrition bars

Oat and soy-based nutrition bars were fortified with 4 levels of fish oil (0, 6, 12, or 18 g per approximately 600 g batch), representing 0%, 20%, 40%, or 60% replacement of canola oil. The commercially available purified fish oil was not emulsified nor encapsulated, and contained tocopherols. Baked nutrition bars were evaluated for proximate composition, water activity, alpha-linolenic acid (ALA), eicosapentaenoic acid (EPA), and docosahexaenoic (DHA) content, and consumer acceptance using a 9-point hedonic scale. The bars were sealed in opaque bags and stored in a stability chamber at 25 °C and 50% relative humidity for 10 wk to assess oxidative stability. There were no significant (P > 0.05) differences in proximate composition, water activity, or ALA levels among treatments. EPA and DHA levels were significantly (P < 0.05) different among treatments, averaging 178.1 mg/serving (20-FO), 488.3 mg/serving (40-FO), and 664.6 mg/serving (60-FO), but none changed during storage. Headspace hexanal and propanal levels decreased over time but were not significantly different among treatments until week 10. Peroxide values were not significantly different except between the control and 60-FO bars. Low values obtained for these analyses suggest negligible oxidation in the bars. Consumer acceptance scores did not differ significantly between the control and lowest fortification level (20-FO), ranging from 6.4 to 6.6 for aroma, texture, flavor, and overall acceptability. These results suggest that nonemulsified, nonencapsulated fish oil can successfully replace canola oil in intermediate moisture nutrition bars to provide EPA and DHA levels as high as 178 mg/serving without affecting consumer acceptability or oxidative stability. Practical Application: Omega-3 fatty acid rich fish oil has been shown to have numerous health benefits, but there are limitations to its use in shelf-stable food products. In this study, nutrition bars were successfully fortified with nonencapsulated, nonemulsified fish oil to deliver 178 mg EPA and DHA per 35 g serving. The fortified bars were oxidatively stable over 10 wk and acceptable to consumers.     

Kinetics of the Water/Air Phase Transition of Radon and Its Implication on Detection of Radon-in-Water Concentrations: Practical Assessment of Different On-Site Radon Extraction Methods

The on-site measurement of radon-in-water concentrations relies on extraction of radon from the water followed by its detection by means of a mobile radon-in-air monitor. Many applications of radon as a naturally occurring aquatic tracer require the collection of continuous radon concentration time series, thus necessitating the continuous extraction of radon either from a permanent water stream supplied by a water pump or directly from a water body or a groundwater monitoring well. Essentially, three different types of extraction units are available for this purpose: (i) a flow-through spray chamber, (ii) a flow-through membrane extraction module, and (iii) a submersible (usually coiled) membrane tube. In this paper we discuss the advantages and disadvantages of these three methodical approaches with particular focus on their individual response to instantaneously changing radon-in-water concentrations. After a concise introduction into theoretical aspects of water/air phase transition kinetics of radon, experimental results for the three types of extraction units are presented. Quantitative suggestions for optimizing the detection setup by increasing the water/air interface and by reducing the air volume circulating through the degassing unit and radon detector are made. It was shown that the flow-through spray chamber and flow-through membrane perform nearly similarly, whereas the submersible membrane tubing has a significantly larger delay in response to concentration changes. The flow-through spray chamber is most suitable in turbid waters and to applications where high flow rates of the water pump stream can be achieved (e.g., where the power supply is not constrained by field conditions). The flow-through membrane is most suited to radon extraction from clear water and in field conditions where the power supply to a water pump is limited, e.g., from batteries. Finally, the submersible membrane tube is most suitable if radon is to be extracted in situ without any water pumping, e.g., in groundwater wells with a low yield, or in long-term time series, in which short-term variations in the radon concentration are of no relevance.