This study investigated the microbial inactivation performance of a novel CO2-based method for food applications on a wide range of process conditions using LB agar cubes. Four different microbial ...strains, Escherichia coli, Listeria innocua, Pseudomonas fluorescens, and Saccharomyces cerevisiae, were homogenously inoculated on the surface of an agar cube and treated with the novel method. The initial microbial loads were 7.46 ± 0.27, 7.38 ± 0.24, 7.47 ± 0.24, and 5.13 ± 0.18 Log CFU/g, respectively. Results showed a similar trend to that of traditional High-Pressure Carbon Dioxide (HPCD) processes in terms of inactivation degree as a function of time and temperature. Notably, greater microbial inactivation occurred at subcritical or near-critical pressure values. Specifically, for P. fluorescens and S. cerevisiae the inactivation rates increased from −0.039 and − 0.094 Log CFU/g/min at 12 MPa to 0.029 and 0.046 Log CFU/g/min at 6 MPa, respectively. At 45 °C and 6 MPa, P. fluorescens and S. cerevisiae were inactivated to undetectable levels after 40 min, while a 60-min treatment was needed for E. coli. L. innocua was more resistant, achieveing after 60 min at 45 °C only 1.32 Log CFU/g inactivation, and requiring a higher temperature to achieve a significant inactivation. Moreover, the gas-to-product volume ratio was proven to affect the inactivation efficiency, a low ratio could represent a limit for achieving high inactivation levels. Future studies will explore the impact of the product's nature, volume and shape, and the use of antimicrobial substances to enhance process performance and apply it to food products, mainly fresh-cut fruit and vegetables, and meat.
High-Pressure Carbon Dioxide (HPCD) processes have shown considerable potential in enhancing food safety and shelf life while preserving nutritional and sensory qualities. However, the industrial implementation of HPCD for solid food processing presents some challenges, especially regarding the potential risk of post-process contamination. This study presents a novel patented process that aims at exploiting the power of HPCD on pre-packed solid food products, facilitating the industrialisation of the method.
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•Temperature notably enhanced the process microbial inactivation for four microbial strains, with observed z-values between 11 and 16 °C.•Increasing the pressure from 6 MPa to 12 MPa did not significantly improve the process performance.•As for traditional supercritical CO2 processes, Listeria exhibited up to four times more resistance to inactivation compared to Gram-negative bacteria and the yeast.•Doubling the CO2-to-product volume ratio increase E. coli inactivation from 1.20 to 2.81 Log CFU/g.
The Key Laboratory of High-temperature and High-pressure Study of the Earth’s Interior belongs to the Institute of Geochemistry, Chinese Academy of Sciences, China. It is a unique and authoritative ...key laboratory at the provincial and ministerial levels. The Key High-Pressure Laboratory is primarily focused on the high-temperature and high-pressure experimental sciences, in combination with filed geophysical observation, theoretical calculation and advanced analysis tests in order to explore the chemical composition, cycling structure, geological state, material circulation, etc., of deep Earth. The mainstream research subjects of the Laboratory mainly include: research and development of experimental platforms and measurement techniques at high temperatures and high pressures; high-pressure material synthesis and hot-pressed sintering techniques; physical and chemical characterizations (e.g. electrical conductivity, thermal conductivity, ultrasonic wave velocity, etc.) of minerals and rocks at conditions of high pressure and different oxygen fugacities by virtue of representative high-pressure apparatus, including autoclaves, piston cylinders, multi-anvil presses, diamond anvil cells and shock waves; high-pressure physiochemical behavior and storage states in the geological fluid and melt of deep Earth interior; high-pressure theoretical calculations; and high-pressure applications in the service of national economical and societal development.
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•High-pressure CO2 is applied to hydrothermal pretreatment of peanut shell.•It dramatically decomposes hemicellulose of pretreated substrate to as low as 1.8%.•It significantly ...increases the pore area and porosity of pretreated substrate.•Pretreated substrate yields 81% glucose leading to 12% increase in bioethanol.•Mechanism behind the dual effect from application of high-pressure CO2 is proposed.
Peanut shells (i.e., an abundant industrial by-product) were subjected to an innovative hydrothermal pretreatment approach using high-pressure CO2 to enhance their enzymatic hydrolysis conversion into glucose. This pretreatment led to a reduction in hemicellulose content in the pretreated peanut shells from 12.4% to as low as 1.8%, which facilitated subsequent conversion into glucose by enzymatic hydrolysis. This pretreatment approach was assessed within a 170–200 °C temperature range and a 20–60 bar CO2 pressure range, after which the results of these conditions were compared to those of conventional hot water pretreatment. Treatment at 190 °C and a 60-bar CO2 pressure was determined to be optimal, resulting in the highest glucose yield (80.7%) from subsequent enzymatic hydrolysis. Acidic conditions resulting from CO2-derived carbonic acid significantly reduced the hemicellulose content of the peanut shells and weakened the interaction between cellulose, hemicellulose, and lignin, improving enzyme accessibility to the cellulose. Furthermore, high-pressure CO2 increased the pore size and porosity of the resulting pretreated peanut shells, improving their enzyme adsorption capacities, as confirmed by cellulase adsorption and mercury intrusion porosimetry tests. The dual effect from high-pressure CO2 led to significant hemicellulose reduction and improved adsorption of enzymes on the cellulose, which in turn increased glucose yield from the subsequent enzymatic hydrolysis of pretreated peanut shells. Alcoholic fermentation of the hydrolyzed glucose resulted in a 12.4% increase in bio-ethanol production compared to a glucose control, thus highlighting the potential of pre-treated peanut shells as a glucose precursor used in biofuel industry.
•Current state-of-the-art in the LC–MS analysis of flavonoids is reviewed.•Theory and applications of UHPLC, HTLC, LC×LC, monoliths and core-shell particles discussed.•Performance and applications of ...latest generation MS instruments outlined for flavonoid analysis.•Cited works point to significant advances in flavonoid analysis by LC–MS.
Flavonoids have elicited significant attention as a result of their importance in plants, their influence on the properties of natural-product derived commodities and especially as a consequence of their purported health benefits. Research in all of these fields relies heavily on accurate analytical data, and in this LC–MS has come to play an influential role by allowing relatively fast tentative identification and accurate quantification of low levels of flavonoids in a variety of matrices. The field has undergone rapid expansion in the last decade due to important developments in both HPLC and MS instrumentation, which nowadays allow much faster and more accurate analysis of flavonoids. This contribution aims to provide an overview of these developments and their application in flavonoid analysis since 2009. The discussion is focussed first on methodologies which provide improved LC separation of flavonoids in terms of speed and/or resolution, including ultra high pressure LC (UHPLC), monolithic and superficially porous phases, high temperature LC (HTLC) and comprehensive two-dimensional LC (LC×LC). The fundamental background relevant to each of these will be briefly outlined, as well as the implications and promise of their hyphenation to MS. Secondly, the possibilities and limitations of a range of the latest MS instruments available in combination with advanced LC analysis will be discussed, including ion trap, triple quadrupole, time-of-flight, Orbitrap, ion mobility and various hybrid instruments. Examples from the latest literature will be used to illustrate the performance gains achievable in flavonoid analysis by the hyphenation of advanced LC separation and high-end MS instrumentation.
Anthocyanins are a group of phenolic compounds responsible for red, blue and violet colouration of many fruits, vegetables and flowers. The high content of these pigments is important as it ...influences directly their health promoting properties as well as the sensory quality of the product; however they are prone to degradation by, inter alia, elevated temperature and tissue enzymes. The traditional thermal methods of food preservation cause significant losses of these pigments. Thus, novel non-thermal techniques such as high pressure processing, high pressure carbon dioxide and high pressure homogenization are under consideration. In this review, the authors attempted to summarize the current knowledge of the impact of high pressure techniques on the stability of anthocyanins during processing and storage of fruit and vegetable products. Furthermore, the effect of the activity of enzymes involved in the degradation of these compounds has been described. The conclusions including comparisons of pressure-based methods with high temperature preservation techniques were presented.
The electroreduction of carbon dioxide (CO2RR) to ethanol is an ideal approach for using released CO2 and producing fuel. The impact of CO2 partial pressure (PCO2) on ethanol synthesis was ...significant but was not well understood. The present study investigates the pressure dependence of ethanol formation from 0.25 bar to 15 bar in a high-pressure flow cell. It displayed a volcano type. The PCO2 associated with the peak Faradaic efficiency (FE) of ethanol increased as the current density increased. The pressure peak values were 0.5 bar, 0.75 bar at 100, 200, and 300 mA cm−2, respectively. Ethanol formation kinetics was affected by adsorbate-adsorbate interactions and the physical blocking of active sites on catalysts with excess CO2. Besides, ethanol synthesis using the configured flue gas, i.e., low-concentration CO2 (VCO2 = 5–30%), was realized via system pressurization from 5 to 20 bar at 200 mA cm−2. By optimizing the combination of CO2 concentration and total pressure (Ptot), the fuel efficiency (FE) of ethanol was maximized to 26.5%. This study uncovers the ideal CO2 partial pressure for ethanol synthesis under industrial current densities, hence presenting potential industrial applications for utilizing flue gas directly in ethanol production.
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•Pressure dependence of ethanol formation exhibited a volcano type.•The PCO2 of the ethanol FE peak increased with the current density.•Ethanol synthesis using the flue gas was realized via pressurization.
Red phosphors AMF6:Mn(4+) (A = Na, K, Cs, Ba, Rb; M = Si, Ti, Ge) have been widely studied due to the narrow red emission bands around 630 nm. The different emission of the zero-phonon line (ZPL) may ...affect the color rendering index of white light-emitting diodes (WLED). The primary reason behind the emergence and intensity of ZPL, taking KNaSiF6:Mn(4+) as an example, was investigated here. The effects of pressure on crystal structure and luminescence were determined experimentally and theoretically. The increase of band gap, red shift of emission spectrum and blue shift of excitation spectrum were observed with higher applied pressure. The angles of ∠FMnF and ∠FMF(M = Si, Ti, Ge) were found clearly distorted from 180° in MF6(2-) octahedron with strong ZPL intensity. The larger distorted SiF6(2-) octahedron, the stronger ZPL intensity. This research provides a new perspective to address the ZPL intensity problem of the hexafluorosilicate phosphors caused by crystal distortion and pressure-dependence of the luminescence. The efficacy of the device featuring from Y3Al5O12:Ce(3+) (YAG) and KNaSiF6:Mn(4+) phosphor was 118 lm/W with the color temperature of 3455 K. These results reveal that KNaSiF6:Mn(4+) presents good luminescent properties and could be a potential candidate material for application in back-lighting systems.
Ultra-high-performance liquid chromatography high-resolution mass spectrometry (UHPLC-HRMS) variants currently represent the best tools to tackle the challenges of complexity and lack of ...comprehensive coverage of the metabolome. UHPLC offers flexible and efficient separation coupled with high-sensitivity detection via HRMS, allowing for the detection and identification of a broad range of metabolites. Here we discuss current common strategies for UHPLC-HRMS-based metabolomics, with a focus on expanding metabolome coverage.
A new type of "Geländer" molecule based on a ortho-tetraphenylene core is presented. The central para-quaterphenyl backbone is wrapped by a 4,4'-di((Z)-styryl)-1,1'-biphenyl banister, with its aryl ...rings covalently attached to all four phenyl rings of the backbone. The resulting helical chiral bicyclic architecture consists exclusively of sp
-hybridized carbon atoms. The target structure was assembled by expanding the central ortho-tetraphenylene subunit with the required additional phenyl rings followed by a twofold macrocyclization. The first macrocyclization attempts based on a twofold McMurry coupling were successful but low yielding; the second strategy, profiting from olefin metathesis, provided satisfying yields. Hydrogenation of the olefins resulted in a saturated derivative of similar topology, thereby allowing the interdependence between saturation and physico-chemical properties to be studied. The target structures, including their solid-state structures, were fully characterized. The helical chiral bicycle was synthesized as a racemate and separated into pure enantiomers by HPLC on a chiral stationary phase. Comparison of recorded and simulated chiroptical properties allowed the enantiomers to be assigned.
The multiferroic material Pb3Mn7O15 exhibits a high resistivity arising from the orbital electrons localized around the manganese ions, which hinders its potential applications. Previous studies ...indicated that the resistivity of Pb3Mn7O15 was influenced by its crystal structure and the distribution of Mn ions. Consequently, pressure-induced structural change are expected to represent a viable method for tuning the resistivity and other properties of this compound. In the present study, the pressure effect on the resistivity of Pb3Mn7O15 was investigated up to 42 GPa. Furthermore, the X-ray diffraction and Raman spectroscopy techniques, along with the density functional theory calculations were employed to study the crystal structure evolution of Pb3Mn7O15 under pressure. The results demonstrate an electronic semiconductor-metal phase transition in Pb3Mn7O15, accompanying an irreversible orthorhombic to monoclinic phase transition. Additionally, within the orthorhombic phase, an iso-structural phase transition is observed, originating from the magnetic moments collapse of manganese cations. This study provides compelling evidence that high-pressure processing can be employed to modulate the crystal structure and functional properties of multifunctional materials.
•Pressure-induced metallization of Pb3Mn7O15(PMO).•The metallization of PMO accompanies a sequence of phase transitions.•The Pnma → P2/m phase transition of PMO is irreversible.
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