The inhibitory effect of the natural seed storage protein arcelin on the development of Acanthoscelides obtectus

To protect stored beans from attack by Acanthoscelides obtectus and other bruchids by non-toxic means of control, it is desirable to combine mutually compatible methods in an integrated approach. A combination of an optimal level of host–plant resistance based on the natural storage protein arcelin and a larval parasitoid has been suggested as a promising two-component strategy. While a dose–response to arcelin is evident in the bruchid Zabrotes subfasciatus, the effects of different arcelin concentrations on A. obtectus are still virtually unknown, even though they might be important for the success of the proposed integrated control system. The current investigation quantified the effect of different arcelin-based resistance levels of beans on the development of A. obtectus in a series of bioassays. Our findings show that all seven tested bean lines with markedly different levels of arcelin-based resistance against Z. subfasciatus consistently prolonged development of A. obtectus. Results provide clear evidence that arcelin acts as a growth inhibitor on first instar larvae. Furthermore, arcelin affected bruchid female fitness through its effect on body mass, which was significantly reduced on all arcelin-containing bean lines. This study demonstrates that, irrespective of its relative concentration, arcelin holds the potential to affect development of A. obtectus sufficiently to support the proposed two-component integrated pest management system.     

Terminal and transient drop rise velocity of single toluene droplets in water

The knowledge of the drop rise velocity in dispersed systems is of fundamental importance. Especially, the residence time is needed for calculation of mass transfer rates in extraction columns. This work deals with fluid dynamic measurements of toluene droplets rising in water ranging from 1.0 to 7.0 mm, with the premise of high purity of the used chemicals. The toluene/water‐system is widely used as a test system with high interfacial tension. A semiempirical correlation for pure systems to predict the terminal velocity of single rising/falling droplets based on experimental data is presented. Results show that a distinction between maximum and characteristic mean values of the drop rise velocity is necessary, especially in the diameter range 2.4–3.0 mm where unexpected velocity fluctuations occur. Two distinct terminal rise velocities were observed for 3 mm droplets. Furthermore, comparisons of the Weber‐Reynolds‐correlation and the drag coefficient with correlations from literature show good agreement. © 2009 American Institute of Chemical Engineers AIChE J, 2009     

Iceberg lettuce as suggested source of a nationwide outbreak caused by two Salmonella serotypes, Newport and Reading, in Finland in 2008

A nationwide outbreak of Salmonella enterica serotypes Newport and Reading occurred between 17 October and 28 November 2008 in Finland. A total of 77 culture-confirmed Salmonella Newport and 30 Salmonella Reading cases, including one case with a double infection, were reported. All strains isolated from the patients were subtyped using serotyping, microbial resistance profiling, and pulsed-field gel electrophoresis (PFGE). Here, the PFGE patterns of the studied Salmonella Newport strains were identical, whereas four different PFGE profiles were found among the Salmonella Reading strains. Two elderly patients died within 2 weeks of the onset of symptoms. Three geographical clusters of cases with an epidemiological link were identified. The traceback investigation suggested that the factor connecting the cases was ready-chopped iceberg lettuce available for mass catering use. However, none of the tested food, environmental samples, or the samples taken from the staff of the processing plant contained Salmonella bacteria. Tracing back to outbreak sources with a short shelf life can be complex.     

Photosensitizers neutral red (type I) and rose bengal (type II) cause light-dependent toxicity in Chlamydomonas reinhardtii and induce the Gpxh gene via increased singlet oxygen formation

The connection between the mode of toxic action and the genetic response caused by the type I photosensitizer and photosynthesis inhibitor neutral red (NR) and the type II photosensitizer rose bengal (RB) was investigated in the green alga Chlamydomonas reinhardtii. For both photosensitizers, a light intensity-dependent increase in toxicity and expression of the glutathione peroxidase homologous gene (Gpxh) was found. The toxicity of RB was reduced by the singlet oxygen (1O2) quenchers 1,4-diazabicyclo[2.2.2]octane and L-histidine, and the RB-induced Gpxh expression was stimulated in deuterium oxide-supplemented growth medium. These observations clearly indicate the involvement of 1O2 in both toxicity and the genetic response caused by RB. NR up-regulated the expression of typical oxidative and general stress response genes, probably by a type I mechanism, and also strongly induced the Gpxh expression. The stimulating effect of deuterium oxide in the growth medium suggested the involvement of 1O2 also in the NR-induced response. Indeed, an increased 1O2 formation was detected with EPR-spin trapping in NR-treated spinach thylakoids. However, none of the 102 quenchers could reduce the light-dependent toxicity of NR in C. reinhardtii, indicating that NR has a different mode of toxic action than RB.     

Influence of light on food relevant fungi with emphasis on ochratoxin producing species

The influence of light of varying wavelength on growth and ochratoxin A biosynthesis of Aspergillus carbonarius, A. niger, A. steynii and on Penicillium nordicum and P. verrucosum was analysed. For comparison the influence of light on various other food relevant fungi, including citrinin producers, was also tested. Generally the Aspergilli seem to be more resistant to light treatment than the Penicillia. Interestingly wavelengths from both sides of the spectrum, e. g. red (long wavelength, 627 nm) and blue (short wavelength 470-455 nm) had the strongest inhibitory effects on growth and ochratoxin A biosynthesis. Blue light generally had a stronger effect. Light of moderate wavelength, 590 to 530 nm, (yellow to green) had more a positive than a negative influence on growth or ochratoxin A biosynthesis compared to the control (dark incubation). The light effect on growth and ochratoxin A biosynthesis was dependent on the growth medium. In contrast to malt extract medium (MEA), YES medium, as an especially nutrient rich medium, had an attenuating effect on the reactivity against light. However the tendency of the response in both media was the same. Moreover, the light intensity strongly influences how the fungus reacts. Depending on the intensity and the resistance of the species a complete cessation of growth and/or inhibition of ochratoxin A biosynthesis could be achieved. Light irradiation has the opposite effect on ochratoxin A than citrinin, two mycotoxins which can be produced simultaneously in P. verrucosum. Citrinin was produced essentially under light conditions which inhibited ochratoxin A biosynthesis. The same was true for a derivative of ochratoxin, in particular a derivative of ochratoxin β in A. carbonarius. A. carbonarius produced high amounts of the ochratoxin β derivative under blue light when the production of ochratoxin A was ceased at the most inhibiting conditions used (MEA, royal blue light, 455 nm, 1700 lx). Light has a growth stalling but not inactivating effect on aerial mycelia. If a non-growing colony under light is shifted to the dark it immediately grows normally. However on spores blue light has a deactivating effect. After incubation of spores of P. verrucosum for 24 h under blue light up to 97% of the spores were no longer able to germinate. Again the spores of the Aspergilli were much more resistant.     

Effect of tumbling and RN genotype on sensory perception of cured-smoked pork loin

Effects of tumbling and RN genotype on sensory perception of cured-smoked loins were studied on loins from 32 crossbred female pigs containing Hampshire blood. Right-side loins were intermittently tumbled during 4 h, whereas left-side loins were left non-tumbled. Tumbled loins were more tender and uniform in cured colour as well as less acidulous in taste compared with non-tumbled loins. Further, the formation of undesirable pores was lower in tumbled loins. Final juiciness tended to be higher and meat taste intensity lower in tumbled loins, whereas initial juiciness did not differ. There were no significant interactions between tumbling and RN genotype for sensory attributes. RN⁻ carriers (RN⁻/rn⁺) were more acidulous in taste, had more pronounced meat taste and were saltier than non-carriers (rn⁺ /rn⁺). Moreover, they tended to have higher initial juiciness and more undesirable pores, and be less homogeneous in cured pink colour. No differences in consumer preference between the four treatments were detected in the ranking test, but most persons ranked non-tumbled loins highest regarding overall liking. Instrumental tenderness measurements agreed well with sensory tenderness scores.     

Inactivation of Shiga toxin-producing O157:H7 and non-O157:H7 Shiga toxin-producing Escherichia coli in brine-injected, gas-grilled steaks

We quantified translocation of Escherichia coli O157:H7 (ECOH) and non-O157:H7 verocytotoxigenic E. coli (STEC) into beef subprimals after brine injection and subsequently monitored their viability after cooking steaks cut therefrom. Beef subprimals were inoculated on the lean side with ca. 6.0 log CFU/g of a five-strain cocktail of rifampin-resistant ECOH or kanamycin-resistant STEC, and then passed once through an automatic brine-injector tenderizer, with the lean side facing upward. Brine solutions (9.9% ± 0.3% over fresh weight) consisted of 3.3% (wt/vol) of sodium tripolyphosphate and 3.3% (wt/vol) of sodium chloride, prepared both with (Lac(+), pH = 6.76) and without (Lac(-), pH = 8.02) a 25% (vol/vol) solution of a 60% potassium lactate-sodium diacetate syrup. For all samples injected with Lac(-) or Lac(+) brine, levels of ECOH or STEC recovered from the topmost 1 cm (i.e., segment 1) of a core sample obtained from tenderized subprimals ranged from ca. 4.7 to 6.3 log CFU/g; however, it was possible to recover ECOH or STEC from all six segments of all cores tested. Next, brine-injected steaks from tenderized subprimals were cooked on a commercial open-flame gas grill to internal endpoint temperatures of either 37.8 °C (100 °F), 48.8 °C (120 °F), 60 °C (140 °F), or 71.1 °C (160 °F). Regardless of brine formulation or temperature, cooking achieved reductions (expressed as log CFU per gram) of 0.3 to 4.1 of ECOH and 0.5 to 3.6 of STEC. However, fortuitous survivors were recovered even at 71.1 °C (160 °F) for ECOH and for STEC. Thus, ECOH and STEC behaved similarly, relative to translocation and thermal destruction: Tenderization via brine injection transferred both pathogens throughout subprimals and cooking highly contaminated, brine-injected steaks on a commercial gas grill at 71.1 °C (160 °F) did not kill all cells due, primarily, to nonuniform heating (i.e., cold spots) within the meat.     

Enhancement of β phase crystals formation with the use of nanofillers in PVDF films and fibres

Nanoclay and carbon nanotubes (CNT) have been in focus recently as means of enhancing β phase crystals formation in poly(vinylidene fluoride)(PVDF). Dominantly, the so-far work has been carried out on films/thin sheets filled with nanoclay. It has been found, mainly from combined XRD and DSC data, that nanoclay influences the PVDF structure, and particularly the β phase crystals formation is enhanced. Results published by various groups are in fairly good agreement. There are no results for nanoclay filled melt-spun PVDF fibres.The influence of CNT on PVDF structure has been less studied. XRD data indicating an enhancing role of multi-wall carbon nanotubes (MWNT) on β phase crystals formation in solution compounded PVDF films are available. Published results for MWNT/PVDF films are not in good agreement. The only study into single-wall carbon nanotube (SWNT)/PVDF has been made on electrospun nanofibres.We explore above findings towards melt-spun nanofilled PVDF fibres. We present new results obtained by us for melt-spun PVDF fibres containing non-functionalized and amino-functionalized double-wall carbon nanotubes (DWNT). The key finding is that amino-DWNT can influence the β to α polymorphic balance.