Sources and dechlorination of polychlorinated biphenyl congeners in the sediments of Fox River, Wisconsin

Polychlorinated biphenyl (PCB) congeners were analyzed in eight deep, dated sediment cores collected from the immediate upstream and downstream of DePere dam in Fox River, Wisconsin. The average time span of the cores is about 100 yr, except for one core (FR-9) which is influenced by mixing or covers a short time period (2 yr). The total PCB concentrations have a range of 0.2-6.8 ppm for the upstream and 0.3-17.6 ppm for the downstream cores. The PCB data obtained from the sampling were analyzed as upstream and downstream data, using a factor analysis (FA) model with nonnegative constraints to identify PCB sources and congener patterns. The factor loadings obtained from the FA model were interpreted in terms of the presence of possible environmental degradation mechanisms. In addition, a recently developed model, which is used to identify and quantify possible pathways of anaerobic dechlorination of PCBs in the sediments, was validated on the basis of in situ data from the literature, and then applied to the congener patterns obtained from the FA model. The major PCB source to the Fox River sediments is identified as Aroclor 1242, for both the upstream and the downstream sediments. Loss of di- and trichlorobiphenyls (e.g., 2-4, 25-2) from the sediments suggests desorption from the sediments. On the other hand, observation of elevated amounts of certain congeners such as 24-3 and 25-3 indicates the presence of anaerobic dechlorination activity. The anaerobic dechlorination model demonstrates significant similarities between the Aroclor 1242 profile altered according to dechlorination processes Q (upstream) and H' (downstream) and the dominant congener patterns obtained from the FA model.     

Undesired phenotypic and genetic trend for stillbirth in Danish Holsteins

The primary aim of this study was to evaluate the phenotypic and genetic trends for stillbirth in Danish Holsteins. Trends of calving difficulty and calf size were also evaluated. The second aim was to compare predicted transmitting abilities (PTA) of sires for stillbirth using a linear and a threshold model. Direct and maternal genetic effects were modeled by fitting correlated additive genetic effects of the sire and the maternal grandsire (MGS). For both the calf and the dam, covariates of breed proportions of Holstein-Friesian (HF) and the heterozygosity between HF and the original Danish Black and White (ODBW) were included. Records from 1.8 million first-calving Danish Holstein cows calving from 1985 to 2002 were used. In this period, the overall frequency of stillbirth increased from 0.071 to 0.090. An unfavorable genetic trend of stillbirth was found for both the direct and maternal effect. The background for the genetic trends was an intense use of HF sires as sires of sons, which increased the proportion of HF genes to 94% in the Danish Holstein calves born in 2002. The effect of the imported HF genes was higher direct effects of calf size, calving difficulty, and stillbirth compared with the ODBW genes. The maternal effect of stillbirth was poorer for HF than for ODBW even though HF had a better maternal calving performance than ODBW. The threshold and the linear models showed almost similar predictions of transmitting abilities of sires.     

PAHs in dated sediments of Ashtabula River, Ohio, USA

Polycyclic aromatic hydrocarbons (PAHs) in dated sediments from Ashtabula River, Ohio, were determined, and a chemical mass balance (CMB) model was used to apportion sources. Three cores (AR-1,AR-2,AR-3) were dated by correlating uranium-supported 210Pb peaks with 1964, 1972, 1977, and 1979 maxima in the discharge record for Ashtabula River. These cores had sedimentation rates between 7.1 and 4.4 cm/year, while a fourth (AR-4) exhibited a much higher rate of 27.8 +/- 18 cm/year. The highest PAH concentration was 11,500 ng/g found in layer 6 of AR-1 (1986), and the lowest was 621 ng/g found in layer 8 of AR-2 (1982). The source contributions to the total PAH concentrations estimated by the CMB model are 0.1-2.2%, 16.8-22.8%, and 78.1-83.8% for wood burning (WB), coke oven (CO), and highway dust (HWY), respectively. Petroleum generated PAHs have maximal contribution during 1977-79, and wood burning PAHs show minimal emissions during 1975-77 in accordance with U.S. consumption records and other studies. Among six PAH markers, only phenanthrene may be subjected to aerobic biodegradation or photolysis with an apparent half-life of 0.005-0.025 year. No anaerobic degradation was observed based on the CMB model. The model works well for the nonmarker compounds, fluoranthene, and benzo[b]fluoranthene/benzo[k]fluoranthene.     

Olfactory and quantitative analysis of volatiles in elderberry (Sambucus nigra L) juice processed from seven cultivars

Aroma compounds emitted from elderberry juices processed from seven cultivars were collected by the dynamic headspace technique and analysed by GC–FID and GC–MS. Forty aroma compounds were identified and quantified, including nine compounds which had not previously been detected in elderberry juice. Significant differences were found among cultivars in the concentration levels of 30 compounds. The sensory characteristics of the individual aroma compounds in elderberry juice were determined by a GC‐sniffing technique, and the compounds were grouped according to their odour. The characteristic elderberry odour is due to dihydroedulan and β‐damascenone, of which the former occurs in relatively high concentrations in the headspace of elderberry juice. The fruity group consisted of aliphatic alcohols and aldehydes and aromatic esters, of which 1‐pentanal, 2‐methyl‐1‐propanol, 2‐ and 3‐methyl‐1‐butanol, 1‐octanal, 1‐octanol and methyl and ethyl benzoate contributed with fruity notes. In the flowery group, 1‐nonanal, nerol oxide and (Z)‐ and (E)‐rose oxide contributed with characteristic elder flower odour, whereas other flowery notes were associated with hotrienol, linalool and α‐terpineol. Fresh and grassy odours were correlated with 1‐hexanal, (E)‐2‐hexen‐1‐al, (Z)‐3‐hexen‐1‐ol, (E)‐2‐hexen‐1‐ol and (E)‐2‐octen‐1‐al of the grassy group, whereas 1‐octen‐3‐ol and 1‐octen‐3‐one of the agrestic group contributed significantly with the characteristic aroma of mushrooms. © 2000 Society of Chemical Industry     

Inhibition of Bacillus cereus spore outgrowth and multiplication by chitosan

Bacillus cereus is an endospore-forming bacterium able to cause food-associated illness. Different treatment processes are used in the food industry to reduce the number of spores and thereby the potential of foodborne disease. Chitosan is a polysaccharide with well-documented antibacterial activity towards vegetative cells. The activity against bacterial spores, spore germination and subsequent outgrowth and growth (the latter two events hereafter denoted (out)growth), however, is poorly documented. By using six different chitosans with defined macromolecular properties, we evaluated the effect of chitosan on Bacillus cereus spore germination and (out)growth using optical density assays and a dipicolinic acid release assay. (Out)growth was inhibited by chitosan, but germination was not. The action of chitosan was found to be concentration-dependent and also closely related to weight average molecular weight (M_w) and fraction of acetylation (F_A) of the biopolymer. Chitosans of low acetylation (F_A = 0.01 or 0.16) inhibited (out)growth more effectively than higher acetylated chitosans (F_A = 0.48). For the F_A = 0.16 chitosans with medium (56.8 kDa) and higher M_w (98.3 kDa), a better (out)growth inhibition was observed compared to low M_w (10.6 kDa) chitosan. The same trend was not evident with chitosans of 0.48 acetylation, where the difference in activity between the low (19.6 kDa) and high M_w (163.0 kDa) chitosans was only minor. In a spore test concentration corresponding to 10²-10³ CFU/ml (spore numbers relevant to food), less chitosan was needed to suppress (out)growth compared to higher spore numbers (equivalent to 10⁸ CFU/ml), as expected. No major differences in chitosan susceptibility between three different strains of B. cereus were detected. Our results contribute to a better understanding of chitosan activity towards bacterial spore germination and (out)growth.     

Relationship between collagen characteristics,lipid content and raw and cooked texture of meat from young bulls of fifteen European breeds

Variations in texture were determined for 10 day aged raw and cooked Longissimus thoracis (LT) muscle from 436 bulls of 15 European cattle breeds slaughtered at an age of 13–16 months. Variations in texture were related to differences in pH 24 h post-mortem, sarcomere length, collagen characteristics and lipid content. The shear force of cooked meat samples varied from 43.8 to 67.4 N/cm². Simmental, Highland and Marchigiana cattle had the highest shear force values and Avileña-Negra Ibérica, Charolais, Casina and Pirenaica cattle had the lowest values. Cooked meat toughness showed a weak negative correlation to lipid content (P < 0.001) but no correlation to collagen characteristics. Raw meat texture measured by compression correlated positively (P < 0.001) with total and insoluble collagen. In conclusion, collagen characteristics showed correlation to raw meat texture but not to cooked meat toughness of LT muscle in European young bulls.     

The relationship between sensory quality and volatile compounds in raw juice processed from elderberries (Sambucus nigra L.)

Elderberry juice was processed by pressing of 101 samples of elderberries (Sambucus nigra L.) picked in Austria, England and Denmark at optimum maturity. Taste panels trained in determination of elderberry flavour evaluated the juices and the results from the sensory evaluation were correlated to the content of volatile compounds. The volatile compounds were isolated from elderberry juices by dynamic headspace technique and analysed by GC-FID and GC-MS. A total of 59 volatile compounds were identified, 9 of which have not previously been detected in elderberry products. A total of 53 compounds occurred in quantifiable amounts and significant differences among the investigated elderberry samples were observed for 50 compounds. The importance of the isolated volatile compounds to elderberry flavour was determined by classical factor analysis using the results from the sensory evaluation and information on the odour of the individual volatile compounds. Classical factor analysis were used including determination of eigenvalues, factor loadings and factor scores by varimax rotation of standardised variables for extraction of four non correlated factors (principal components) explaining approximately 73% of the variation in elderberry flavour. Twenty-eight volatile compounds and sensory quality were included in the four factors. Using the compounds with highest numerical values (loadings) the four factors were named: fresh-elderberry-elder flower (35.2%), fresh-fruity-sweet (17.3%), fresh-fruity (13.7%) and green-floral-fruity (6.7%). Three compounds with characteristic elderberry odour (-damascenone, nonanal, dihydroedulan) were closely correlated with the sensory quality of elderberry together with compounds with fruity, floral, green and/or miscellaneous odours.