High Hydrostatic Pressure Technique Research Articles

Challenges for room temperature operation of electrically pumped GeSn lasers

Recent demonstrations of room-temperature lasing in optically pumped GeSn show promise for future CMOS compatible lasers for Si-photonics applications. However, challenges remain for electrically pumped devices. Investigation of the processes that limit device performance is therefore vital in aiding the production of future commercial devices. In this work, a combined experimental and modelling approach is utilised to explore the dominant loss processes in current devices. By manipulating the band structure of functioning devices using high hydrostatic pressure techniques at low temperature, the dominant carrier recombination pathways are identified. This reveals that 93±\\documentclass[12pt]{minimal} \\usepackage{amsmath} \\usepackage{wasysym} \\usepackage{amsfonts} \\usepackage{amssymb} \\usepackage{amsbsy} \\usepackage{mathrsfs} \\usepackage{upgreek} \\setlength{\\oddsidemargin}{-69pt} \\begin{document}$$~\\pm ~$$\\end{document}5% of the threshold current is attributable to defect-related recombination at a temperature, T = 85 K. Furthermore, carrier occupation of L-valley states (carrier leakage) is responsible for 1.1±\\documentclass[12pt]{minimal} \\usepackage{amsmath} \\usepackage{wasysym} \\usepackage{amsfonts} \\usepackage{amssymb} \\usepackage{amsbsy} \\usepackage{mathrsfs} \\usepackage{upgreek} \\setlength{\\oddsidemargin}{-69pt} \\begin{document}$$~\\pm ~$$\\end{document}0.3% of the threshold current, but this sharply increases to 50% with a decrease of just 30 meV in the L-Γ\\documentclass[12pt]{minimal} \\usepackage{amsmath} \\usepackage{wasysym} \\usepackage{amsfonts} \\usepackage{amssymb} \\usepackage{amsbsy} \\usepackage{mathrsfs} \\usepackage{upgreek} \\setlength{\\oddsidemargin}{-69pt} \\begin{document}$$\\Gamma$$\\end{document} separation energy. This indicates that thermal broadening of a similar order may reproduce these adverse effects, limiting device performance at higher temperatures. Temperature dependent calculations show that carrier occupation of indirect valley L-states strongly affects the transparency carrier density and is therefore very sensitive to the Sn composition, leading to an effective operational temperature range for given Sn compositions and strain values. Recommendations for future device designs are proposed based on band structure and growth optimisations.

Current Technologies and Uses for Fruit and Vegetable Wastes in a Sustainable System: A Review.

The fruit and vegetable industry produces millions of tons of residues, which can cause large economic losses. Fruit and vegetable wastes and by-products contain a large number of bioactive substances with functional ingredients that have antioxidant, antibacterial, and other properties. Current technologies can utilize fruit and vegetable waste and by-products as ingredients, food bioactive compounds, and biofuels. Traditional and commercial utilization in the food industry includes such technologies as microwave-assisted extraction (MAE), supercritical fluid extraction (SFE), ultrasonic-assisted extraction (UAE), and high hydrostatic pressure technique (HHP). Biorefinery methods for converting fruit and vegetable wastes into biofuels, such as anaerobic digestion (AD), fermentation, incineration, pyrolysis and gasification, and hydrothermal carbonization, are described. This study provides strategies for the processing of fruit and vegetable wastes using eco-friendly technologies and lays a foundation for the utilization of fruit and vegetable loss/waste and by-products in a sustainable system.

Impact of high hydrostatic pressure on the single nucleotide polymorphism of stress-related dnaK, hrcA, and ctsR in the Lactobacillus strains

Lactic acid bacteria (LAB) are widespread in environments and can either have a positive impact because their ability to survive in harsh conditions and influence the product (probiotic properties, change of structure-EPS [exopolysaccharides], etc.), or a negative impact, (so not needed) because of their spoilage ability (beer, juices). High hydrostatic pressure (HHP), one of the non-thermal preservation methods used in the food industry, can force the LAB to activate the adaptative mechanisms. Under pressurization, the changes in the bacteria cells can occur at the transcriptional or translational level. This study evaluated the HHP on the single nucleotide polymorphism (SNP) changes in three genes, dnaK, ctsR, and hrcA, related to the stress-response mechanism in LAB. The correlation between the DNA polymorphism and the gene expression under HHP stress was assessed. The applied pressure of 300 MPa resulted in a low ratio of nonsynonymous substitutions to the synonymous substitutions (0 to 1.12), and a lower number of mutations was observed for pressurized strains (from 6 in hrcA to 11 in dnaK) than in controlled (from 3 in ctsR to 92 in hrcA). In all pressurized strains, the expression of genes was observed, whereas, in control strains, the gene expression was detected in three out of five strains. Although there was a noticeable change in stress-related gene expression after HHP, there was no correlation with SNPs. At the same time, with a high frequency of synonymous changes in nucleotide and high diversity for hrcA and dnaK, a very low diversity was found in ctsR sequences. The LAB strains stress response mechanisms are much more complex. The study requires information on the general mechanism and changes in the membranes’ composition, proteome changes, and gene expression patterns. The mutations in genes related to stress can have important implications for the strains’ fitness effect and adaptive ability of LAB strains, especially considering their food industry implication where the HHP techniques are used.

Impact of high hydrostatic pressure on the single nucleotide polymorphism of stress-related dnaK, hrcA, and ctsR in the Lactobacillus strains

Lactic acid bacteria (LAB) are widespread in environments and can either have a positive impact because their ability to survive in harsh conditions and influence the product (probiotic properties, change of structure-EPS [exopolysaccharides], etc.), or a negative impact, (so not needed) because of their spoilage ability (beer, juices). High hydrostatic pressure (HHP), one of the non-thermal preservation methods used in the food industry, can force the LAB to activate the adaptative mechanisms. Under pressurization, the changes in the bacteria cells can occur at the transcriptional or translational level. This study evaluated the HHP on the single nucleotide polymorphism (SNP) changes in three genes, dnaK, ctsR, and hrcA, related to the stress-response mechanism in LAB. The correlation between the DNA polymorphism and the gene expression under HHP stress was assessed. The applied pressure of 300 MPa resulted in a low ratio of nonsynonymous substitutions to the synonymous substitutions (0 to 1.12), and a lower number of mutations was observed for pressurized strains (from 6 in hrcA to 11 in dnaK) than in controlled (from 3 in ctsR to 92 in hrcA). In all pressurized strains, the expression of genes was observed, whereas, in control strains, the gene expression was detected in three out of five strains. Although there was a noticeable change in stress-related gene expression after HHP, there was no correlation with SNPs. At the same time, with a high frequency of synonymous changes in nucleotide and high diversity for hrcA and dnaK, a very low diversity was found in ctsR sequences. The LAB strains stress response mechanisms are much more complex. The study requires information on the general mechanism and changes in the membranes’ composition, proteome changes, and gene expression patterns. The mutations in genes related to stress can have important implications for the strains’ fitness effect and adaptive ability of LAB strains, especially considering their food industry implication where the HHP techniques are used.

High Hydrostatic Pressure Treatment Ensures the Microbiological Safety of Human Milk Including Bacillus cereus and Preservation of Bioactive Proteins Including Lipase and Immuno-Proteins: A Narrative Review.

Breast milk is the nutritional reference for the child and especially for the preterm infant. Breast milk is better than donated breast milk (DHM), but if breast milk is not available, DHM is distributed by the Human Milk Bank (HMB). Raw Human Milk is better than HMB milk, but it may contain dangerous germs, so it is usually milk pasteurized by a Holder treatment (62.5 °C 30 min). However, Holder does not destroy all germs, and in particular, in 7% to 14%, the spores of Bacillus cereus are found, and it also destroys the microbiota, lipase BSSL and immune proteins. Another technique, High-Temperature Short Time (HTST 72 °C, 5–15 s), has been tried, which is imperfect, does not destroy Bacillus cereus, but degrades the lipase and partially the immune proteins. Therefore, techniques that do not treat by temperature have been proposed. For more than 25 years, high hydrostatic pressure has been tried with pressures from 100 to 800 MPa. Pressures above 400 MPa can alter the immune proteins without destroying the Bacillus cereus. We propose a High Hydrostatic Pressure (HHP) with four pressure cycles ranging from 50–150 MPa to promote Bacillus cereus germination and a 350 MPa Pressure that destroys 106 Bacillus cereus and retains 80–100% of lipase, lysozyme, lactoferrin and 64% of IgAs. Other HHP techniques are being tested. We propose a literature review of these techniques.

Effect of high hydrostatic pressure treatments on volatiles of berry purées

High hydrostatic pressure (HHP) technology, as a promising alternative of thermal-treatment and chemical preservatives, can be used to produce minimally processed foods. It has the advantage of affecting only non-covalent bonds of macromolecules in foods, and thus preserves nutritional components, taste, and flavour exceptionally well. However, HHP also influences enzymatic reactions of food. Although some of these changes are often beneficial, monitoring the potential effects of high pressure treatments — especially in the field of product and technology development — is essential. The aim of this study was to point out some parameters of high hydrostatic pressure technique (pressure, temperature, build-up time, holding time, number of cycles) that can substantially impact the sensory properties of treated products.

The effect of high hydrostatic pressure on the microbiological quality and physical–chemical characteristics of Pumpkin (Cucurbita maxima Duch.) during refrigerated storage

Abstract Pumpkins were processed at high hydrostatic pressure (HHP) ranging from 350 to 550 MPa for 0.5 min to 30 min. Two different nonlinear mathematical models were compared to fit the inactivation kinetics. The second model consistently produced better fits to the inactivation data than the first model (Weibull model). According to the inactivation of microorganisms, pumpkin was subjected to 450 MPa/15 min and 550 MPa/10 min. The microbiological and physicochemical changes in pumpkin subjected to (HHP) and thermal-treated (854 °C/5 min) were compared during 4 °C storage. The total plate counts (TPC) treated with thermal processing, 450 MPa/15 min and 550 MPa/10 min were 5.12, 4.02 and 1.71 log 10 CFU/g, respectively on the 60th day. The growth of microorganisms caused the increase in ΔE , decrease in hardness in other treatments. Treatment of 550 MPa for 10 min had little effect on color during storage. There were no significant changes in the L ⁎ , a ⁎ and b ⁎ values (p > 0.05). The hardness of pumpkin treated with 550 MPa/10 min decreased by 32.28% after 60 days. A greater retention of the original color, Vc and antioxidant capacity and increased total phenols were observed in 550 MPa/10 min-treated samples immediately after processing. During storage, color changed, Vc content, total phenols and the antioxidant activity were decreased. While the soluble solids content (SSC), sugars and pH value of pumpkin with HHP or thermal treatment did not show significant change immediately during 60-day storage. Based on these results, working at 550 MPa for 10 min ensures physicochemical and high standard of sanitation parameters in pumpkin. Industrial relevance Pumpkin ( Cucurbita maxima Duch.) is one of the popular vegetables, and fresh-cut pumpkin requires strict processing treatment and storage conditions to protect its quality. HHP is one promising novel non-thermal technique and is likely to replace thermal processes. A better knowledge of effects of storage temperature on the quality of HHP-treated pumpkin and its storage time prediction through microbiological quality and physical–chemical characteristics analysis of these changes is necessary. The available data would provide technical support for commercial application of the HHP technique in fresh-cut pumpkin processing.

English

The effect of different treatment conditions (pressure, treatment time, and temperature), as well as composition of pectin solution (Pectin, Ca++ ion and sugar concentration, pH) on gel formation of two types of low methoxylpectins were investigated. The results have shown that with increasing pressure, time or temperature during high hydrostatic pressure (HHP) treatment, the gel hardness increased continuously. Up to 2.5 times higher gel hardness could be achieved after HHP treatment (550 MPa, 35°C, 10 min, and 2% pectin) compared to untreated sample. Higher sugar concentration in pectin solution (about 30 to 60%) resulted in drastically increasing the gel hardness for untreated as well as HHP treated samples but the overall gel hardness was, in the case of HHP treated samples, distinctly higher than the untreated. Similar results could be observed if the Ca++ ion concentration increased up to 90 mg/g pectin. Increasing the pH of pectin solution from pH = 3.4 to 5.6 decreased the gel hardness in the case of untreated as well as HHP treated samples. The results of this study confirmed that it is possible to produce firm gel from low methoxylpectin at temperature of £35°C using high hydrostatic pressure technique.   Key words: Low methoxylpectin, gels, high hydrostatic pressure.

Changes of quality of high hydrostatic pressure processed cloudy and clear strawberry juices during storage

Changes of quality of cloudy and clear strawberry juices processed by high hydrostatic pressure (HHP) at 600 MPa/4 min during 6-month storage at 4 and 25 °C were investigated. After 6 months of storage at 4 °C, ascorbic acid, anthocyanins and total phenols decreased by 39.41%, 29.76% and 16.22% in cloudy juices, and by 48.91%, 7.02% and 13.82% in clear juices, but the antioxidant capacity in both juices decreased by less than 10%. The decrease of these indices at 25 °C for 6 months almost doubled. The lightness (L⁎) and redness (a⁎) in both juices at 25 °C were significantly lower than at 4 °C, while total difference color (ΔE) and browning degree (BD) were significantly higher. 66.93% and 70.75% decreases of viscosity and 47.60% and 79.98% of cloud in cloudy juices were observed after 6 months of storage at 4 and 25 °C, respectively. The loss of ascorbic acid, anthocyanins, total phenols and antioxidant capacity fits well to a first-order equation. Total anthocyanin content was selected as a biomarker to predict the shelf life due to their influence on the consumer acceptance and higher sensitivity to the storage temperature. Strawberry juice is one of the popular fruit juices, and it requires strict processing treatment and storage conditions to protect its quality. HHP is one promising novel non-thermal technique and is likely to replace thermal processes. A better knowledge of effects of storage temperature on the quality of HHP-treated strawberry juice and its shelf life prediction through kinetics analysis of these changes is necessary. This study would provide technical support for commercial application of the HHP technique in strawberry juice processing.

Physical–chemical and sensory properties of pulsed electric field and high hydrostatic pressure treated citrus juices

Abstract The consumers have increasing desire towards fresh, long shelf-life and healthy products by consisting favourable sensory properties. As an ambivalent fact appears that the product should meet all these requirements and should be consumable long time. All these demands lead to the importance of the minimal processing methods. The properties of widely common citrus juices (100% orange, – grapefruit, – and tangerine juice) were analyzed by measuring the possible changes in the physical–chemical parameters (pH, Brix°, electric conductivity, colour) respectively the aroma and acid content. The applied technology was pulsed electric field (in furthers: PEF) treatment with the parameters of 28 kV/cm with 50 pulses; respectively high hydrostatic pressure (HHP) technology with the parameter of 600 MPa pressure for 10 min treatment time. The sensory properties of the juices were analyzed with electronic-nose and -tongue to measure the possible changes of the treated juices compared to the untreated (control) samples with the help of these electronic tools, which can serve as a potential detection system for the differentiation of the treatments mentioned above. Industrial relevance Fruit juices are preserved mainly by heat treatment which can change many prosperous flavour- , acid and sensory properties. The present work shows in case of citrus juices the application of pulsed electric field treatment and high hydrostatic pressure techniques as non-thermal preservation possibilities and the use of electronic tongue and – nose as a new method for sensory testing.

Impact of traditional and innovative technologies on some characteristics and bioactive compounds of Opuntia macrorhiza juice

In addition to flavonols and the high contents of betacyanins, O. macrorhiza fruit is rich in vitamin C. Different pre- extraction techniques were used aiming at increasing bioactive compounds and yield of O. macrorhiza juice. In comparison to untreated fruit's mash, the mash was treated prior to pressing with four pre-extraction techniques, (1) pulsed electric field (PEF), (2) thermal treatment using microwaves, (3) enzymatic treatment with commercial pectolytic enzymes, and (4) a combination of thermal and enzymatic treatments. The mashes treated enzymatically or by combination of thermal and enzymatic treatments produced higher yields of the juice. Although all treatments led to no significant differences in total content of betacyanins, all treatments provided significantly higher contents of flavonol glycosides compared to the untreated mash. Subsequently, the juice was preserved by three preservation technologies: Pulsed Electric Field (PEF), High Hydrostatic Pressure (HHP), and Pasteurization. Antioxidant activity of pasteurized juice was slightly lower than juices preserved by PEF and HHP techniques.

High-hydrostatic pressure technique is an effective method for the preparation of PVA–heparin hybrid gel

To develop an antithrombotic material for preparation of small-diameter vascular graft, we describe a novel method to prepare a poly(vinyl alcohol) (PVA)–heparin hydrogels prepared by high-hydrostatic pressure (HHP, 980 MPa), which is designed for sustained release of heparin. Antithrombogenic test revealed that HHP method would not affect the antithrombin III (ATIII) activity of the released heparin. The distribution of heparin in the polymer matrix was homogeneous than freeze–thawing gel, due to the fast gelling affect of PVA which takes approximately 10 min for gel formation. The formation of intra- and intermolecular hydrogen bonds between PVA chains has trapped the heparin inside, suppressing the phase separation between PVA and heparin. Furthermore, evenly distribution of heparin induced the formation of heparin and PVA molecular complex, which brought the sustained release of heparin from the PVA despite the high swelling ratio. Our results show that it is possible to prepare a PVA–heparin hybrid gel which can be applied as an effective material for an antithrombotic system without using any chemical agent.

HIGH HYDROSTATIC PRESSURE EXTRACTION OF SALIDROSIDE FROM RHODIOLA SACHALINENSIS

ABSTRACT A nonthermal process, high hydrostatic pressure (HHP), was used as a new extraction technique to obtain salidroside from Rhodiola sachalinensis. The leaching rates of salidroside were measured under different treatment conditions. When the material was treated under 500 MPa of hydrostatic pressure with 50 times of volume 60% (v/v) of ethanol solution as the extracting solvent, the leaching rate of salidroside was up to 0.401% in 3 min, while that of ultrasonic extraction was at 0.288% in 30 min and that of reflux extraction was at 0.302% in 120 min. The HHP extraction technique showed high efficiency in extracting salidroside at room temperature using moderate ethanol concentration.PRACTICAL APPLICATIONS Rhodiola is prevalently used as a safe and effective antifatigue drug and as an adaptogen around the world. But the common extraction methods used to yield commercial products are still traditional ones, which could easily lead some thermosensitive ingredients to lose their biologic activities. The nonthermal extraction method is the key point of the realization of herb modernization. The high hydrostatic pressure (HHP) technique can be operated at room temperature and can shorten processing time. The extract produced by the method has proved to be of higher extraction yield than traditional varieties. In addition, the HHP technique only consumes electric energy without exhaust emission, which is an environment‐friendly method. In the future, we will cooperate with those far‐seeing companies to achieve its industrialization. The annual sale of herbs in the whole world has reached 30 billion. We do not doubt the prospect of this technique.

High Pressure and Protein Oligomeric Dissociation

High hydrostatic pressure techniques - in the absence or presence of externally added chaotropes - are increasingly used as tools to study dissociation and unfolding of protein aggregates [1]. G. Weber had reported some causes for the pressure-induced dissociation of oligomeric proteins: imperfect van der Waals contact between monomers, solvent electrostriction at the level of salt linkages at the interfaces of monomers-subunits, and solvation of the non-polar groups at the boundaries of contact in the oligomers [2]. In this paper, we present some typical examples from recent publications and from the laboratory.

Structural features and transport processes of superionic conductors based on tin(II) fluoride

The thermal behavior and transport properties of lead(II) tetrafluorostannate(II) have been investigated by impedance spectroscopy,19F NMR and high hydrostatic pressure techniques. It is shown that these experimental methods are powerful tools to clarify ionic transport processes in the investigated solid electrolytes with predominant fluorine mobility.

Analysis of sea urchin egg cortical transformation in the absence of cortical granule exocytosis

A burst of endocytosis accompanying microvillar elongation follows cortical granule exocytosis in normal sea urchin development. By 5 min postfertilization the burst is over and a lower level of endocytosis ensues (constitutive phase). To determine whether microvillar elongation and initiation of endocytosis are necessary concommitants of cortical granule exocytosis we utilized Chases's (1967, Ph.D. thesis, University of Washington, Seattle) high-hydrostatic pressure technique to block the latter and then examined developing eggs for endocytosis and microvillar elongation. To accomplish this, eggs were fertilized, after which hydrostatic pressure was quickly raised to 6000–7000 psi at the start of cortical granule exocytosis and maintained for 5 min. Only the cortical granules immediately surrounding the sperm penetration site were secreted (about 3% or less of the egg's total number of cortical granules). Blockage of major cortical granule exocytosis had the following consequences on surface events during first division: (1) The endocytosis burst normally associated with cortical granule exocytosis was effectively eliminated as was early microvillar elongation and elevation. Both occurred to a limited extent around the sperm penetration site which resulted in a highly localized surface transformation. (2) By 20 min after fertilization endocytosis began over the rest of the egg surface in the absence of any further cortical granule exocytosis. (3) Subsequently, during a 30-min period starting midway between fertilization and first cleavage microvilli more than doubled in length and endocytosis levels increased severalfold. These events brought about a complete surface transformation similar to that which normally occurs in early development but in the absence of cortical granule exocytosis. By first cleavage surfaces and cortices of high-pressure-treated and control eggs were nearly indistinguishable except for the presence of cortical granules in cortices of the former. Pressure-treated eggs cleaved normally and developed to larval forms overnight. The period of late surface transformation in high-pressure-treated Strongylocentrotus purpuratus eggs corresponds in timing and some of its characteristics to second phase microvillar elongation observed in normal development in this species and also in S. droebachiensis development. These observations suggest, therefore, that microvillar elongation and endocytosis are necessary membrane remodelling events which must occur for normal development even in the absence of membrane addition from the cortical granules.