Combined high pressure–sub-zero temperature processing of smoked salmon mince: phase transition phenomena and inactivation of Listeria innocua

International audienceSmoked salmon mince inoculated with Listeria innocua was subjected to various combined high pressure- low or sub-zero temperature treatments. Temperature in the sample and in the pressure-transmitting medium (PTM) were monitored against pressure in order to detail undercooling, ice nucleation and phase transition under pressure. Freezing at 0.1 MPa with subsequent storage at −28 °C or −40 °C for 5 days did not induce any microbial inactivation. Inactivation of L. innocua by pressurisation at 207 MPa for 60 min without ice crystal formation was higher (1.1 log cycle) at sub-zero temperatures (down to −21 °C) than at 4 °C (0.7 log cycle). Pressure-shift freezing from 207 MPa and −22 °C, followed by further freezing to −25 °C at 0.1 MPa, induced 1.4 or 1.9 log cycle reduction of L. innocua, depending on whether pressure was released rapidly (∼3 s) or slowly (18 min), respectively. Freezing samples at −28 °C and 0.1 MPa for 24 h followed by pressurisation at 207 MPa and −29 °C for 23 min, then fast pressure release resulted in a 2.5 log cycle reduction for L. innocua. When sample freezing was followed by pressure-assisted thawing at 207 MPa and in PTM at 10 °C for 23 min, a reduction of 1.2 log cycle was obtained. None of the combined high pressure–sub-zero temperature treatments was found to induce sub-lethal injury of L. innocua dispersed in smoked salmon mince

Combined high pressure–sub-zero temperature processing of smoked salmon mince: phase transition phenomena and inactivation of Listeria innocua

International audienceSmoked salmon mince inoculated with Listeria innocua was subjected to various combined high pressure- low or sub-zero temperature treatments. Temperature in the sample and in the pressure-transmitting medium (PTM) were monitored against pressure in order to detail undercooling, ice nucleation and phase transition under pressure. Freezing at 0.1 MPa with subsequent storage at −28 °C or −40 °C for 5 days did not induce any microbial inactivation. Inactivation of L. innocua by pressurisation at 207 MPa for 60 min without ice crystal formation was higher (1.1 log cycle) at sub-zero temperatures (down to −21 °C) than at 4 °C (0.7 log cycle). Pressure-shift freezing from 207 MPa and −22 °C, followed by further freezing to −25 °C at 0.1 MPa, induced 1.4 or 1.9 log cycle reduction of L. innocua, depending on whether pressure was released rapidly (∼3 s) or slowly (18 min), respectively. Freezing samples at −28 °C and 0.1 MPa for 24 h followed by pressurisation at 207 MPa and −29 °C for 23 min, then fast pressure release resulted in a 2.5 log cycle reduction for L. innocua. When sample freezing was followed by pressure-assisted thawing at 207 MPa and in PTM at 10 °C for 23 min, a reduction of 1.2 log cycle was obtained. None of the combined high pressure–sub-zero temperature treatments was found to induce sub-lethal injury of L. innocua dispersed in smoked salmon mince

Microbial inactivation by pressure-shift freezing: effects on smoked salmon mince inoculated with Pseudomonas fluorescens, Micrococcus luteus and Listeria innocua

International audienceSmoked salmon mince inoculated simultaneously with Listeria innocua, Micrococcus luteus and Pseudomonas fluorescens was subjected to different pressure–temperature conditions. Control freeze–thaw at 0.1MPa with storage at −15°C or −40°C for 0–5 days did not induce microbial inactivation. Control pressurisation at 207MPa for 23min at 20°C (initial sample temperature) with fast (3s) pressure release had no significant effect on Gram+bacteria while P. fluorescens underwent a 2.8 log cycle reduction. Pressurisation at 207MPa for 23min at −3°C (without ice crystal formation) enhanced microbial reduction to 3.8 log cycles for P. fluorescens and to about 0.5 log cycle for Gram+bacteria. “Pressure-shift nucleation” (PSN) from 207MPa and −21°C (i.e. cooling at 207MPa for 23min followed by pressure release in 3s) caused 1.2, 1.4 and 4.3 log cycle reductions of L. innocua, M. luteus and P. fluorescens, respectively. A reduction of 1.7 log cycle was observed for L. innocua and M. luteus (4.6 log cycle for P. fluorescens) when salmon mince was subjected to pressure-shift freezing (PSF) (i.e. PSN from 207MPa and −21°C as above followed by further freezing to −25°C at 0.1MPa). PSF with pressure release in 18min enhanced reduction to 2 and 2.5 log cycles for L. innocua and M. luteus, respectively

Identification of decorin derived peptides with a zinc dependent anti-myostatin activity

International audienceDecorin is a member of the small leucine-rich proteoglycan family and it is a component of the extracellular matrix. Decorin was previously shown to bind different molecules, including myostatin, in a zinc-dependent manner. Here, we investigated in detail the anti-myostatin activity of decorin and fragments thereof. We show that this protein displays in vitro anti-myostatin activities with an IC(50) of 2.3 × 10(-8)M. After intramuscular injection of decorin in dystrophic mdx and γ-sarcoglycan(-/-) mice, we observed a significant increase of the muscle mass and this effect was maximal 18 days after administration. Further, we show that the myostatin-binding site is located in the N-terminal domain of decorin. In fact, a peptide encompassing the 31-71 sequence retains full myostatin binding capacity and intramuscular injection of the peptide induces muscle hypertrophy. The evaluation of three additional peptides suggests a crucial role of the four cysteines within the conserved CX3CXCX6C motif of class I of the small leucine-rich proteoglycans. Altogether, our results show that the N-terminal domain of decorin is sufficient for the binding to myostatin and they underscore the crucial role for this interaction of zinc and the cysteine cluster

Effects of high pressure homogenisation of raw bovine milk on alkaline phosphatase and microbial inactivation. A comparison with continuous short-time thermal treatments

International audienceRaw whole milk of high microbial quality (58 degrees C), but markedly decreased above 200 MPa when Tin=24 degrees C (T2>60 degrees C). In contrast to inactivation induced by continuous short-time thermal treatments, ALP inactivation induced by HP homogenisation was clearly due to mechanical forces (shear, cavitation and/or impact) in the HP valve and not to the short (<1 s) residence time at temperature T2 in the same valve. Inactivation of the three exogenous microorganisms led to similar conclusions. Homogenisation at 250 MPa or 300 MPa (Tin=24 degrees C) induced a 2-3 log cycle reduction of the total endogenous milk flora and a 1.5-1.8 log cycle reduction of inoculated List. innocua. Higher reduction ratios (2-4 log cycles) were obtained for the two other microorganisms. The highest levels of ALP inactivation corresponded to the highest extents of microbial reduction. Running the milk twice or three times through the homogeniser (recycling), keeping temperature T1 approximately 29 degrees C and pressure=200 MPa, increased homogenisation efficiency

Control of inherited accreted lithospheric heterogeneity on the architecture and the low, long-term subsidence rate of intracratonic basins

International audienceIntracratonic basins tend to subside much longer than the timescale predicted by thermal relaxation of the lithosphere. Many hypotheses have been suggested to explain their longevity, yet few have been tested using quantitative thermo-mechanical numerical models, which capture the dynamic of the lithosphere. Lithospheric-scale geodynamic modelling preserving the tectono-stratigraphic architecture of these basins is challenging because they display only few kilometres of subsidence over 1000 of km during time periods exceeding 250 Myr. Here we present simulations that are designed to examine the relative role of thermal anomaly, tectonics and heterogeneity of the lithosphere on the dynamics of intracratonic basins. Our results demonstrate that initial heterogeneity of accretionary continental lithosphere explains long-term subsidence and the arches-basins architecture of Saharan type intracratonic basins at first order. The simulations show that initially heterogeneous lithospheres inherited from accretion are strong enough to resist local isostatic re-equilibration for very long period of time. Indeed, the lateral density variations store potential gravitational energy that is then slowly dissipated by differential erosion and slow vertical movements. For relatively well-accepted coefficient of erosion of 10−6 m2/s, the subsidence last longer than 250 Myr. Extensional tectonic forcing and thermal anomalies both result in an effective strength drop of the lithosphere, which allows a temporal acceleration of local isostatic re-equilibration. Periodic changes in far field tectonic forcing from extension to compression complicate the tectono-stratigraphic architecture (intra-basin arches, sub-basins) introducing stratigraphic unconformities between different neighbouring basins such as the ones observed in North Africa

HOw strawberry can flower continuously?

HOw strawberry can flower continuously?. Europeen Plant Science Organisation (EPSO) conference "Plant for life

HOw strawberry can flower continuously?

HOw strawberry can flower continuously?. Europeen Plant Science Organisation (EPSO) conference "Plant for life