Search

Objective: Exploring the disinfection effect of high-pressure carbon dioxide (HPCD) on human coronavirus 229E (hCoV-229E). Methods: The human coronavirus 229E (hCoV-229E) was treated by HPCD at different temperatures (10, 25, and 37 ℃) and pressures (6.3 and 10 MPa) for different time (15 and 30 min). Result: Compared with the control groups under the corresponding temperatures, the virus titer in 50 mL tube treated with HPCD at 10 ℃ and 6.3 MPa for 30 min was significantly decreased (P

The presence of tens of Clostridium botulinum spores per gram of honey can cause infantile botulism. Thermal treatment is insufficient to inactivate these resistant forms. This study explored the effectiveness of supercritical CO2 (scCO2) on its own and combined with lemon (LEO), clove (CLEO), and cinnamon (CEO) essential oils on the inactivation of Clostridium sporogenes (CECT 553) as a surrogate of Clostridium botulinum. In water, the degree of inactivation at 10 MPa after 60 min increased with the increasing temperature, reducing the population by 90% at 40 °C and by 99.7% at 80 °C. In contrast, when applied to honey, scCO2 did not inactivate Clostridium spores satisfactorily at temperatures below 70 °C, which was related to the protective effect of honey. Meanwhile, scCO2 modified with CEO (<0.4% mass) improved the inactivation degree, with a 1.3-log reduction achieved at 60 °C. With this same mixture, a reduction of 3.7 logs was accomplished in a derivative with 70% moisture. Honey was very sensitive to the temperature of the applied CO2. The obtained product could be used as a novel food, food ingredient, cosmetic, or medicine. [ABSTRACT FROM AUTHOR]

High-pressure carbon dioxide (HPCD), a novel non-thermal pasteurization technology, has attracted the attention of scientists due to its high pasteurization efficiency at a lower temperature and pressure. However, the inactivation mechanism has not been well researched, and this has hindered its commercial application. In this work, we used a sub-lethal HPCD condition (4.0 MPa, 30 °C) and a recovery condition (30 °C) to repair the damaged cells. Transcriptome analysis was performed by using RNA sequencing and gene ontology analysis to investigate the detailed lethal mechanism caused by HPCD treatment. RT-qPCR analysis was conducted for certain upregulated genes, and the influence of HPCD on protoplasts and single-gene deletion strains was investigated. Six major categories of upregulated genes were identified, including genes associated with the pentose phosphate pathway (oxidative phase), cell wall organization or biogenesis, glutathione metabolism, protein refolding, phosphatidylcholine biosynthesis, and AdoMet synthesis, which are all considered to be associated with cell death induced by HPCD. The inactivation or structure alteration of YNL194Cp in the organelle membrane is considered the critical reason for cell death. We believe this work contributes to elucidating the cell-death mechanism and providing a direction for further research on non-thermal HPCD sterilization technology. [ABSTRACT FROM AUTHOR]

This study investigated the microbial inactivation performance of a novel CO 2 -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. [Display omitted] • 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 CO 2 processes, Listeria exhibited up to four times more resistance to inactivation compared to Gram-negative bacteria and the yeast. • Doubling the CO 2 -to-product volume ratio increase E. coli inactivation from 1.20 to 2.81 Log CFU/g. [ABSTRACT FROM AUTHOR]

In this study, we applied widely targeted metabolomics and physiological analysis to investigate the non-volatile metabolites changes and regulatory mechanisms of high-pressure carbon dioxide (HPCD) treatment on the yellowing of fresh-cut Chinese water chestnut (CWC). A total of 349 non-volatile metabolites were identified and subjected to principal component analysis (PCA), OPLS-DA and KEGG enrichment analysis. The results showed that the yellowing of fresh-cut CWC was related to membrane lipid metabolism and flavonoid biosynthesis. Damage stress induced membrane lipid metabolism and flavonoid biosynthesis in surface tissues, and the increase of phenylalanine ammonia-lyase (PAL) activity in flavonoid biosynthesis might be triggered by signaling molecules from membrane lipid metabolism. On the one hand, HPCD treatment could directly inhibit the activity of PAL, and reduce the biosynthesis of flavonoids in the damaged tissues. On the other hand, HPCD could indirectly inhibit the generation and accumulation of potential signaling molecules by regulating membrane lipid metabolism, thus preventing signaling molecules from triggering flavonoid biosynthesis. This study proposed a potential network of HPCD regulating the yellowing of fresh-cut CWC and established the foundation for further control of yellowing in fresh-cut CWC. [Display omitted] • The first time to study fresh-cut CWC yellowing using widely targeted metabolomics. • HPCD may regulate the generation of signaling molecules in membrane lipid metabolism. • HPCD can directly inhibit PAL activity and prevent flavonoid biosynthesis. • A potential network of HPCD regulating fresh-cut CWC yellowing was established. [ABSTRACT FROM AUTHOR]

High-pressure carbon dioxide (HPCD), a novel non-thermal pasteurization technology, has attracted the attention of scientists due to its high pasteurization efficiency at a lower temperature and pressure. However, the inactivation mechanism has not been well researched, and this has hindered its commercial application. In this work, we used a sub-lethal HPCD condition (4.0 MPa, 30 °C) and a recovery condition (30 °C) to repair the damaged cells. Transcriptome analysis was performed by using RNA sequencing and gene ontology analysis to investigate the detailed lethal mechanism caused by HPCD treatment. RT-qPCR analysis was conducted for certain upregulated genes, and the influence of HPCD on protoplasts and single-gene deletion strains was investigated. Six major categories of upregulated genes were identified, including genes associated with the pentose phosphate pathway (oxidative phase), cell wall organization or biogenesis, glutathione metabolism, protein refolding, phosphatidylcholine biosynthesis, and AdoMet synthesis, which are all considered to be associated with cell death induced by HPCD. The inactivation or structure alteration of YNL194Cp in the organelle membrane is considered the critical reason for cell death. We believe this work contributes to elucidating the cell-death mechanism and providing a direction for further research on non-thermal HPCD sterilization technology.

• HPCD prevents bacterial contamination during enzymatic hydrolysis process. • HPCD treatment removes the threat of pathogenic bacteria and histamine producer. • HPCD treatment of 1 MPa 50 °C condition makes no influence on hydrolysates. The 2011–2016 reports from the Food and Agriculture Organization of the United Nations has stated that annual food loss and waste occurs on a massive scale in fisheries and aquaculture. This study aimed to explore advanced technologies to recycle wasted salmon as an industrial resource with high commercial value by applying enzymatic hydrolysis under HPCD. Our results showed that HPCD treatment at 50 °C and 1 MPa for 16 h effectively prevents salmon from microbial contamination. Real-time PCR analysis demonstrated that HPCD was also able to inhibit an increase in bacteria at moderate temperatures. Based on NGS analysis, there was a very low abundance of Bacillus and some histamine producers, such as Pseudomonas , Acinetobacter, Enterobacter , and Klebsiella, detected in samples treated using HPCD at 50 °C and 1 MPa for 16 h. Hydrolysate analysis showed that HPCD treatment at 1 MPa did not affect the hydrolysates from salmon. It is anticipated that the results from this study will support the application of HPCD in industrial enzymatic hydrolysis and increase the sustainability of bio-based materials. [ABSTRACT FROM AUTHOR]

The effect of high-pressure carbon dioxide processing on inactivation of aerobic mesophilic bacteria and Escherichia coli ATCC 25922 inoculated in human milk was investigated. The effect of the ratio between sample mass and CO2 (1:0.2; 1:0.6 and 1:1 m/m); depressurization rate (1, 5.5 and 10 MPa/min); and pressure cycling (1, 3 and 5) were the process variables studied. The best reductions in aerobic mesophilic bacteria as well as in E. coli (>6.0 and >5.0 log, respectively) were obtained with a ratio of 1:1, a depressurization rate of 10 MPa/min, and one cycle of pressurization/depressurization. The depressurization rate was found to be an important variable in the inactivation process. The results suggest that high-pressure carbon dioxide processing can be applied to human milk as a safe alternative to the pasteurization employed in human milk banks.

The demand for safe, high-quality food has greatly increased, in recent times. As traditional thermal pasteurization can significantly impact the nutritional value and the color of fresh food, an increasing number of nonthermal pasteurization technologies have attracted attention. The bactericidal effect of high-pressure carbon dioxide has been known for many years, and its effect on food-related enzymes has been studied. This novel technology has many merits, owing to its use of relatively low pressures and temperatures, which make it a potentially valuable future method for nonthermal pasteurization. For example, the inactivation of polyphenol oxidase can be achieved with relatively low temperature and pressure, and this can contribute to food quality and better preserve nutrients, such as vitamin C. However, this novel technology has yet to be developed on an industrial scale due to insufficient test data. In order to support the further development of this application, on an industrial scale, we have reviewed the existing information on high-pressure carbon dioxide pasteurization technology. We include its bactericidal effects and its influence on food quality. We also pave the way for future studies, by highlighting key areas. [ABSTRACT FROM AUTHOR]

The new global trends for consuming natural products rich in bioactive compounds and health-promoter phytochemicals have increased the modern consumer's interest in fruit and vegetable juices. But, the current technologies based on thermal treatments reduce the nutritional value and degrade sensory attributes of these products in relation to the fresh-like juices. Supercritical carbon dioxide (SC–CO 2) technology has emerged as a potential non-thermal technology for the inactivation of spoilage and pathogenic microorganisms and endogenous enzymes responsible for the deterioration of fruit and vegetable juices. Likewise, non-thermal SC-CO 2 processing can preserve the compounds associated with beneficial health effects besides maintaining sensory attributes. Thus, the effects of the SC-CO 2 technology on the microbial and enzymatic inactivation, nutritional compounds, physicochemical properties, sensory attributes and shelf-life of the fruit and vegetable juices are discussed. SC-CO 2 technology is a promising technique for the processing of fresh fruit and vegetable juices in a non-thermal way. SC-CO 2 processing is able to inactivate microbial and enzymatic load of plant-based juices in the temperature range of 35–55 °C and pressure range of 10–60 MPa. SC-CO 2 treated juices are sensorially similar to the fresh-like products with their nutritional value and physicochemical characteristics very close to the unprocessed juices. Under cold storage conditions, the juices stabilized by SC-CO 2 treatment achieved a microbial shelf-life of at least 20 days with quality attributes of freshly juice, depending on their processing parameters and type of juice. However, additional studies are required to perform process optimization, exploring the synergism among its main variables in the same way that economic viability studies are needed. • Supercritical carbon dioxide technology as a non-thermal process was reviewed. • Nutritional compounds, sensory attributes, and shelf-life of natural juices were discussed. • Recent advances in microbial and enzymatic inactivation were summarized. • This review highlighted advances on the non-thermal processing of plant-based juices. [ABSTRACT FROM AUTHOR]

Accurate measurement and prediction of the phase behaviour of mixtures involved in a chemical process are crucial for its optimisation. Given the importance of CO 2 conversion technologies and considering possible benefits of CO 2 -ionic liquid biphasic systems, i.e., facilitating a product separation, we investigated the high-pressure behaviour of components of interest in a recently developed process of cyclic carbonate synthesis directly from CO 2 and potentially bio-based alcohols. The solubility of 1,2-butanediol and 1,2-butylene carbonate in a dense carbon dioxide phase was determined experimentally at the temperature of 313.2 K and pressures between 6 and 18 MPa. The influence of 1-hexyl-3-methylimidazolium tris(pentafluoroethyl)trifluorophosphate ionic liquid, [hmim][FAP], as a solvent, on the solubility of these compounds in CO 2 -rich phase, in ternary (CO 2 + 1,2-butanediol + [hmim][FAP]), CO 2 + butylene carbonate + [hmim][FAP]) and quaternary (CO 2 + 1,2-butanediol + butylene carbonate + [hmim][FAP]) mixtures was investigated. The experimental results of the two binary systems were correlated using the density-based Chrastil equation. The knowledge of phase equilibria behaviours reported in this work will be useful for designing chemical conversions of carbon dioxide using [hmim][FAP] ionic liquid as reaction solvents. [Display omitted] • solubility of 1,2-butanediol and butylene carbonate in dense CO 2. • phase behaviour of ternary and quaternary CO 2 -IL biphasic mixtures. • 1-hexyl-3-methylimidazolium tris(pentafluoroalkyl)trifluorophosphate ionic liquid as solubility modifier. [ABSTRACT FROM AUTHOR]

This study investigated the effect of different states of CO 2 on the activity and structural modification of purified polyphenol oxidase (PPO) from apple juice. CO 2 in critical and supercritical states strongly inhibited the PPO activity up to 64.88% and 3.20%, respectively. Dynamic light scattering analysis showed that the two peaks depolymerised into three peaks in the critical state, demonstrating the dissociation and aggregation of small particles. Circular dichroism analysis revealed that the secondary structure deformed because of the loss of α-helix contents in the critical and super critical CO 2 states. Fluorescence intensity dramatically decreased to 251.3 (λ max 312) in the critical state, showing unfolding of PPO molecules thereby resulting in quenching and blue shifting of λ max. Electrophoresis indicated that large molecular aggregates did not run into the gel at supercritical state. Hence, HP-CO 2 treatment in critical and super critical states could induce the aggregation, deformation and structural changes which might be the causes of PPO inactivation. "Polyphenol oxidation (PPO) is the enzyme that initiates the browning reaction and deteriorates the quality of fruit juices". High pressure carbon dioxide (HP-CO 2) technology is a promising technique to obtain high quality apple juices with low enzyme activity. This study analyzed the effects of different states of carbon dioxide gases under HPCD on the activity, aggregation, deformation and structural changes of PPO from apple juice. Available findings provided in this study will benefit the food industry. • Critical and supercritical states of CO 2 strongly inhibited the PPO activity, thus stabilizing the quality of apple juice. • HP-CO 2 processing caused dissociation, conformation and aggregation of PPO. • Structural modifications in relation to activation and inactivation of PPO were studied. [ABSTRACT FROM AUTHOR]

A high-pressure carbon dioxide technique was optimized by employing of response surface methodology. A quadratic model was used to predict process behavior. According to results, the extraction time (20–60 min) and pressure (100–200 bars) had statistically significant effects on anthocyanin, total phenolic, ascorbic acid contents and antioxidant activity of barberry fruit extracts. The maximum yields of anthocyanins, phenolic compounds, and vitamin C were 178.658 mg/L, 329.815 mg GAE/100 mL, and 3468.7 mg/L, respectively. Antioxidant activity of about 84% was also achieved. The optimum extraction pressure and time were defined as 200 bars and 44.64 min, respectively. Experimental values for various responses at the optimum conditions matched with the predicted values. High-performance liquid chromatography revealed the presence of six different types of anthocyanins, namely cyaniding-3,5-diglucoside, delphinidin-3,5-diglucoside, delphinidin-3-glucoside, pelargonidin-3,5-diglucoside, cyanidin-3-glucoside, and pelargonidin-3-glucoside in the samples. Response surface methodology was employed successfully to optimize the extraction conditions of barberry fruit bioactive compounds. [ABSTRACT FROM AUTHOR]

The effect of high-pressure carbon dioxide processing on inactivation of aerobic mesophilic bacteria and Escherichia coli ATCC 25922 inoculated in human milk was investigated. The effect of the ratio between sample mass and CO2 (1:0.2; 1:0.6 and 1:1 m/m); depressurization rate (1, 5.5 and 10 MPa/min); and pressure cycling (1, 3 and 5) were the process variables studied. The best reductions in aerobic mesophilic bacteria as well as in E. coli (>6.0 and >5.0 log, respectively) were obtained with a ratio of 1:1, a depressurization rate of 10 MPa/min, and one cycle of pressurization/depressurization. The depressurization rate was found to be an important variable in the inactivation process. The results suggest that high-pressure carbon dioxide processing can be applied to human milk as a safe alternative to the pasteurization employed in human milk banks. [ABSTRACT FROM AUTHOR]

In this study, the changes in enzyme activities, total polyphenols, phenolic profile, and physicochemical properties from thermally (25−75 °C) and high-pressure carbon dioxide (HP-CO2) (25−65 °C/20 MPa)-treated apple juice were investigated. The HP-CO2 exhibited complete inactivation of polyphenol oxidase (PPO) at 65 °C, whereas PPO was still active at 75 °C under thermal processing (TP). Similarly, the relative activity of peroxidase (POD) significantly decreased by 71% at 65 °C under HP-CO2 processing, whereas TP was less effective. HP-CO2 and TP treatments at 65 °C reduced the browning degree (BD) value to 0.47 and 0.89, respectively. Thus, HP-CO2 inhibits the browning reactions caused by PPO and POD enzymes at each operating temperature. The concentration of epicatechin and catechin increased significantly with increasing temperature above 45 °C in TP-treated juices. HP-CO2 treatment increased the same phenolic compounds at 35 °C and 9 MPa, whereas high-temperature and -pressure conditions caused insignificant changes in concentration of epicatechin and catechin. Changes in others phenolic compounds were insignificant under TP and HP-CO2 treatment. Overall, HP-CO2 is a promising technology to get high-quality juices with lower enzyme activity.

Synthesis of benzyl methyl ether from benzyl alcohol and methanol in high-temperature carbonic water was studied in a batch reactor. Benzyl methyl ether formation was not observed by reacting benzyl alcohol with only methanol under supercritical conditions at 573 K. On the other hand, benzyl methyl ether was formed by the treatment of benzyl alcohol in an aqueous methanol solution at 573 K. 12% of benzyl methyl ether yield was obtained in aqueous methanol solution (methanol to water molar ratio of 0.025 mol/0.11 mol) at 573 K in 60 min and the yield enhanced to 33% by the addition of 18 MPa of carbon dioxide to the aqueous solution. As the etherification is an acid catalyzed reaction, the protons derived from the dissociation of water molecules could be responsible for the etherification of benzyl alcohol in an aqueous methanol solution at 573 K. The enhancement of benzyl methyl ether yield by the addition of carbon dioxide in aqueous methanol solution is caused by the increase of the number of protons derived from carbonic acid, which is formed in high-temperature liquid water under high-pressured carbon dioxide. [ABSTRACT FROM AUTHOR]

High-pressure carbon dioxide switchable solution with 1,8-diazabicyclo [5.4.0] undec-7-ene (DBU) and ethylene glycol (EG) was applied for a dissolution and modification of cellulose derived from a cassava pulp waste. The switchable solution of DBU and EG were formed by adding carbon dioxide under a pressure range of 0.1–10.0 MPa and a temperature range of 298 and 333 K. The cellulose was dissolved into the CO 2 switchable system at a pressure of 0.1 and 5.8 MPa and a temperature of 313 K. The precipitates of bicarbonate salt of reaction between DBU and carbon dioxide were observed in the switchable solution at the higher pressures and lower temperatures. The cellulose was also modified in the switchable solution with the ionized DBU, EG and carbon dioxide as analyzed by Fourier transform infrared spectroscopy. The modified cellulose was then utilized for the fabrication of the transparent film. [ABSTRACT FROM AUTHOR]

High-pressure carbon dioxide (HPCD) is widely used in the food industry, but some scientific issue is still unclear, especially the effect on the proteins. In this work, the effect of HPCD on the color, polypeptide chains, α-helix contents, and spectroscopy of amino acid residues of myoglobin (Mb) was investigated by a comparison that the samples were treated with different pressures of 7, 21, and 35 MPa at 35 °C for 30 min. The results showed that during the HPCD treating, there is relative α-helix content increase sharply from 17.02 to 21.81 % for all the treated samples with increasing CO pressures, while the fluorescence and synchronous fluorescence spectroscopy analysis showed that the intrinsic relative fluorescence intensity of amino acid residues increases. Interestingly, it is found that there is no direct effect of HPCD on polypeptide chains and interior structure of Mb. [ABSTRACT FROM AUTHOR]

Synergetic effects of high-pressure carbon dioxide (HPCD) and nisin on Escherichia coli and Staphylococcus aureus were evaluated. Changes in morphology, interior structure, and membrane permeability were analyzed by scanning and transmission electron microscopy, and flow cytometry. Synergetic effects were found, especially in S. aureus. HPCD alone or with nisin led to morphological and intracellular alterations in both bacteria, but nisin alone led to these damages only in S. aureus . A positive correlation between membrane damage and inactivation was found, but ratios of inactivation were higher, probably because of viable but non-culturable state. Mechanisms were proposed for synergism: for E. coli , outer membrane was damaged first by HPCD, and then HPCD and nisin jointly acted on and destroyed the cytoplasmic membrane, leading to further intracellular damage by HPCD; for S. aureus , HPCD and nisin acted on the cytoplasmic membrane together leading to cell death. Industrial Relevance Escherichia coli and Staphylococcus aureus are two common microorganisms, which exist widely in the environment and easily contaminate food such as vegetables and dairy products, respectively. Considering heat treatment may destroy some heat-sensitive quality of the products, this study evaluated synergetic effects of high-pressure carbon dioxide (HPCD) combined with the bacteriocin nisin. The investigations provided evidence for potentially combined application of HPCD and nisin to help keep food safe in the industry. [ABSTRACT FROM AUTHOR]

Changes of microbial, physicochemical and sensory properties of mulberry juice processed by high hydrostatic pressure (HHP) (500 MPa/5 min), high-pressure carbon dioxide (HPCD) (15 MPa/55 °C/10 min), and high-temperature short time (HTST) (110 °C/8.6 s) during 28 days of storage at 4 °C and 25 °C were investigated. Total aerobic bacteria (TAB) and yeast and mold (Y&M) were not detected in HHP-treated and HTST-treated mulberry juices for 28 days at 4 °C and 25 °C, but were detected more than 2 log CFU/ml in HPCD-treated mulberry juice for 21 days at 4 °C and 14 days at 25 °C, respectively. Total anthocyanins were retained after HHP and reduced by 4 % after HTST while increased by 11 % after HPCD. Total phenols were retained by HHP, while increased by 4 % after HTST and 16 % after HPCD. The antioxidant capacity was retained by HTST and HHP and increased by HPCD. Both total phenols and antioxidant capacity were decreased during the initial 14 days but then increased up to 28 days regardless of storage temperature. The value of polymeric color and browning index decreased and a* increased in HHP-treated and HPCD-treated mulberry juices, while HTST-treated mulberry juice had a reverse result. The viscosity of mulberry juice increased in HHP-treated and HPCD-treated juices, while decreased in HTST-treated juice. During storage, total anthocyanins, total phenols, and antioxidant capacity and color in all mulberry juices decreased more largely at 25 °C than that at 4 °C. Better quality was observed in HHP- and HPCD-treated mulberry juices, and a longer shelf life was observed in HHP-treated samples compared to HPCD-treated ones. [ABSTRACT FROM AUTHOR]

A combined treatment based on high-pressure carbon dioxide and high-power ultrasound (HPCD + HPU) technologies was investigated for the pasteurization of fresh-cut coconut. Inactivation kinetics of both the natural microbiota and Salmonella enterica typhimurium spiked on the product were determined at 12 MPa and 10 W, delivered every 2 min of treatment, as a function of temperature (from 24 to 50 °C) and treatment time (from 5 up to 30 min). Additionally, to study the effect of HPCD + HPU on the quality of the product, physicochemical attributes (total acidity, pH, color, texture, dry matter, fat content, enzymatic activity, antioxidant capacity, phenols, flavonoids, and phenolic acids) were measured after the combined treatment and during a refrigerated shelf life of 4 weeks. The results revealed that HPCD + HPU increased microbial inactivation rates compared with HPCD alone: 8 log reductions of S. typhimurium were achieved with HPCD + HPU at 12 MPa, 40 °C, 20 min, while just a 4 log reduction was achieved with HPCD alone. Similar results were obtained for the natural microbiota; milder conditions of temperature and pressure were sufficient to assure inactivation to undetectable levels even of mesophilic microorganisms, the most resistant ones. Total acidity and pH did not change after the combined treatment and during the entire storage of 4 weeks, while slight differences were observed for the other physicochemical parameters. Overall, the results showed the feasibility and the potential of HPCD + HPU as an innovative non-thermal technology for the pasteurization of fresh-cut fruits. [ABSTRACT FROM AUTHOR]

Coconut water is a tropical beverage with a distinctive odor and flavor that has until now not been adequately characterized. In the present paper, the volatile compound composition of coconut water was investigated using head space solid-phase microextraction-gas chromatography-mass spectrometry (HS-SPME-GC-MS). Analyses were made of fresh untreated (FU) samples and samples pasteurized using two different technologies: conventional thermal treatment (thermal pasteurization (TP)) and high-pressure carbon dioxide (HPCD) pasteurization, which has recently attracted great interest as an innovative nonthermal preservation treatment. Seventy-three volatile compounds were identified; 27 of them reported for the first time in coconut water. The results showed that HPCD treatment depletes short- and medium-chain alcohols, while TP treatment triggers an increase in aldehydes, ketones, and 2-acetyl-1-pyrroline, an aroma compound active at low odor thresholds and characterized by 'popcorn' and 'toasted' odor descriptors. Sensory discrimination analysis (triangle test) showed there to be no significant differences between HPCD and FU samples, while TP and FU samples were perceived significantly differently. Descriptive sensory analyses evidenced more intense 'cooked,' 'toasted bread,' and 'hazelnut' characteristics in TP-treated coconut water, consistent with HS-SPME-GC-MS data. In conclusion, instrumentally measurable changes in volatile compounds were more moderate with HPCD than with TP treatment and were not sensorially perceivable compared with the FU product. [ABSTRACT FROM AUTHOR]

The influence of high-pressure carbon dioxide (HPCD) treatment on the browning of fresh-cut lettuce was investigated during storage at 4 °C. The browning degree, color, weight loss, browning-related enzymes, and components related to membrane lipid metabolism of fresh-cut lettuce were assessed during storage. The results showed that HPCD treatment slowed down the browning of fresh-cut lettuce. Polyphenol oxidase activity and total phenolic content of HPCD-treated group were reduced by 53.50% and 74.63%, respectively. In addition, HPCD treatment inhibited lipoxygenase activity and delayed membrane lipid peroxidation, thus decreasing PAL's stimulation by membrane lipid peroxidation products and further reducing the synthesis of phenolic. On the other hand, HPCD treatment maintained the structural integrity of the cell membrane and prevented the cell membrane compartmentalization from being broken due to cell membrane breakage by inhibiting phospholipase D activity, which avoided the contact between enzyme and phenol and delayed the oxidative browning. [ABSTRACT FROM AUTHOR]

Highlights: [•] Hydrophobic behavior of lotus-leaf-like structure can be achieved. [•] Rough surface caused by TiO2 nanoparticles on fiber was coated with fluoropolymer. [•] Ultrasonic shock waves accelerated deagglomeration and coating of TiO2 nanoparticles. [ABSTRACT FROM AUTHOR]

This study assessed the inactivation of microorganisms naturally present in raw bovine milk by high-pressure carbon dioxide (HPCD) at 10-30 MPa and 20-50 °C for 20-70 min. The log reduction of microorganisms increased as raw bovine milk was exposed to higher pressures and temperatures and longer treatment times. The maximum reduction of aerobic bacteria (AB) was 4.96-log at 25 MPa and 50 °C for 70 min. At lower temperatures and treatment times, a complete inactivation of yeasts and moulds (Y&M) and coliform bacteria (CB) was obtained at 25 MPa. Changes in microorganisms naturally present in raw bovine milk during storage were also assessed. There were 1.83-log survival of AB, 0.65-log survival of Y&M and a complete inactivation of CB in raw bovine milk when subjected to HPCD at 25 MPa and 40 °C for 50 min. Moreover, the AB, Y&M and the CB in raw bovine milk exhibited insignificant alterations during storage at 4 °C for 15 days, indicating a potential capability of HPCD to extend the shelf life of milk. [ABSTRACT FROM AUTHOR]

The effect of pressured carbon dioxide on heterogeneous hydrogenation of benzaldehyde and homogeneous dehydration of sorbitol in water solvent was studied. Initial hydrogenation rates of benzaldehyde over a charcoal-supported palladium catalyst in water at 313 K were enhanced by the addition of carbon dioxide. The initial rate increased with an increase in carbon dioxide pressure and became a maximum at 5 MPa. Dehydration of sorbitol proceeded in water phase at 500 K and initial dehydration rates were enhanced by addition of 30 MPa of carbon dioxide. [Figure not available: see fulltext.] [ABSTRACT FROM AUTHOR]

Abstract: A novel carbonation route for the synthesis of CaCO3 is reported with high pressure CO2 scintillated into dry Ca(OH)2 powder containing a solid ionic liquid (SIL, tetra-n-heptyl-ammonium bromide). Results show that calcite structure with rhombohedral lattice is produced at all CO2 conditions investigated: supercritical (15.0MPa, 50.0°C), compressed (5.0MPa, 30.0°C), liquid (15.0MPa, 25.0°C), gaseous (0.1MPa, 30.0°C) and atmospheric (0.1MPa, 30.0°C). Furthermore, rapid and complete conversion is achieved under the supercritical condition with the production of nano-sized calcite particles, suggesting that coupling SIL with CO2 could be an effective system for enhancing traditional gas–solid reactions. A mechanism for the rapid gas–solid carbonation reaction is proposed with emphasis on the initialization of the reaction by tiny adsorbed water and CO2 dissolved in the SIL. [Copyright &y& Elsevier]

Abstract: Dehydration of 1,4-butanediol (1,4-BDO) to tetrahydrofuran (THF), 2R,5R-hexanediol (2R,5R-HDO) to 2,5-dimethyltetrahydrofuran (2,5-DMTHF), and 2,5-dimethyl-2,5-hexanediol (2,5-DM-2,5-HDO) to 2,2,5,5-tetramethyltetrahydrofuran (2,2,5,5-TMTHF) proceeded in high-temperature liquid water at 523K. The formation rates of cyclic ethers were enhanced by high-pressure carbon dioxide (16.2MPa). The order of dehydration rates in high-temperature water with carbon dioxide was 2,5-DM-2,5-HDO>2R,5R-HDO>1,4-BDO (tertiary>secondary>primary alcohols), which was the same order as the stability of corresponding carbocation species. [Copyright &y& Elsevier]

Abstract: The individual and combined effects of high-pressure carbon dioxide (HPCD), mild heat (MH) and nisin (200 ppm) on the inactivation of natural microorganisms, including aerobic bacteria (AB), yeasts and molds (Y&M), in litchi juice were evaluated. The samples were treated at a pressure of 10 MPa and temperatures of 32, 42 or 52 °C for 5, 10, 15, 20, 25 or 30 min. Temperature played a prominent role in the inactivation of both AB and Y&M when combined with HPCD, particularly for AB at 52 °C and Y&M at temperatures ≥42 °C. Nisin increased the susceptibility of AB to the combined treatment of HPCD and MH (HPCD + MH). A reduction of 4.19 log cycles was achieved by HPCD + MH at 52 °C for 15 min, and complete inactivation of AB was obtained by combination of HPCD, MH and nisin (HPCD + MH + nisin). No significant effect of nisin was found on the inactivation of Y&M. [Copyright &y& Elsevier]

In this paper, we described the use of high-pressure carbon dioxide (HPCD) for the inactivation of natural microbes in lychee juice and evaluated its effects on lychee juice quality, compared to a conventional high-temperature, short-time (HTST) method. The HPCD treatments were carried out using a HPCD unit (8 MPa, 36 °C, 2 min), and the HTST was performed at 90 °C for 60 s. The results showed that five log reduction for yeasts and molds and total aerobic microorganisms occurred at 8 MPa for 2 min. And effects of the treatments on pH and concentrations of microbes, organic acids, titratable acidity (TA), total soluble solid (TSS), sugars, polyphenols, color, and free amino acids were also investigated. HPCD could efficiently maintain the concentration of polyphenols and original color at 8 MPa, 36 °C for 2 min. Insignificant differences in colors were observed between unprocessed and HPCD juices, while significant differences were observed between unprocessed and HTST juices. Furthermore, HTST decreased the total free amino acids, whereas HPCD caused a significant increase (increased by 45.92% at 8 MPa) ( p < 0.05). The increase in total amino acids induced by HPCD treatment is beneficial for nutritional value of commercial ready-to-drink lychee juice. In general, HPCD treatment had less influence on the measured quality parameters of lychee juice than HTST treatment. Therefore, HPCD treatment could be a useful alternative to traditional heat treatment. [ABSTRACT FROM AUTHOR]

Abstract: High-pressure carbon dioxide (HPCD) treatment is currently considered as an attractive non-thermal process for preserving food. Since the first level of interaction between HPCD and the bacterial cells is lowering of the pH, knowledge of the pH of a food product in contact with CO2 at high-pressure conditions is essential for a better understanding of the inactivation mechanism of HPCD. Therefore, a mathematical model was developed to predict the pH in complex aqueous food systems in contact with CO2 at high-pressure conditions as function of pressure, temperature and buffer capacity. In addition, a spectrofluorometric method using calcein as fluorescent pH indicator was designed for the in situ measurement of the pH of complex aqueous systems in contact with pressurized CO2 as function of pressure (10.5–18.0MPa), temperature (25–35°C), initial pH (4.0–8.0), working volume ratio (41.6–70.0%) and broth composition (0.1M citrate buffer, 0.1M phosphate buffer and 10% whey protein). To mimic a complex matrix, the bacterial Brain Heart Infusion (BHI) broth was used. In general, there was a good agreement between the measured and predicted pH values. Only for the lowest initial pH of the broth, a discrepancy between the measured and calculated pH values was noticed, implying that the proposed model needs some further refinement to properly take into account non-ideality of the liquid phase. Furthermore, the pH of the broth was significantly influenced by the initial pH of the solution but was not dependent on pressure, temperature and working volume ratio. The addition of complementary buffers to the broth also influenced the pH drop and this effect was dependent on the initial pH of the solution. [ABSTRACT FROM AUTHOR]

The inactivation of polyphenol oxidase (PPO) in peach juice and PPO in carrot juice was investigated by high-pressure carbon dioxide (HPCD), and their inactivation kinetics was analysed and compared. The temperature was 35-55 °C, the pressure was 5-15 MPa under HPCD condition. Results showed that HPCD enhanced the inactivation effect of the temperature on the two PPOs. The inactivation kinetics of peach PPO was well fitted to a first-order kinetic model, of carrot PPO to a fraction-conversion model as a function of temperatures or pressures. Susceptibility of the rate constant k of peach PPO was not altered and of carrot PPO was lessened to the temperature, but the susceptibility of the rate constant k of peach PPO and carrot PPO to the pressure was not changed when the pressure was >8 or 12 MPa, indicating the presence of a threshold pressure. [ABSTRACT FROM AUTHOR]

Aims: The objective of this study was to investigate whether bacterial cells could develop resistance (as a part of their adaptation strategy) to high-pressure CO2 (HPCD) inactivation. Methods and Results: Alternating cycles of exposure to pressurized CO2 (10·5 MPa, 35°C, 400 min−1, 70% working volume ratio during 10 min) and re-growth of the surviving subpopulation were used to investigate possible increases in the resistance of Escherichia coli and Listeria monocytogenes to HPCD. The results show an increased resistance of both pathogens tested after seven cycles of inactivation. Increase in the resistance after 15 cycles resulted in a difference of 2·4 log CFU ml−1 in log N0/Ni when parental (N0) and treated cultures (Ni) of E. coli and L. monocytogenes were compared. Conclusions: Current findings indicate the ability of micro-organisms to adapt to HPCD preservation technology. Significance and Impact of the Study: The occurrence of HPCD-resistant micro-organisms could pose a new hazard to the safety and stability of HPCD-processed foods. [ABSTRACT FROM AUTHOR]

High-temperature liquid water treatment of triol compounds [1,2,3-propanetriol (glycerol), 1,2,4-butanetriol (1,2,4-BTO), and 1,2,5-pentanetriol (1,2,5-PTO)] was carried out using a batch reactor. Intramolecular dehydration to hydroxyacetone from glycerol, 3-hydroxytetrahydrofuran from 1,2,4-BTO, and both tetrahydrofurfuryl alcohol and 3-hydroxytetrahydropyran from 1,2,5-PTO proceeded in water at 573 K. The dehydration rates were enhanced by the addition of high-pressure carbon dioxide. [ABSTRACT FROM AUTHOR]

Abstract: The inactivation of pectin methylesterases (PMEs) from carrot and peach in buffer by high-pressure carbon dioxide (HPCD) at 55°C was investigated. The two PMEs were effectively inactivated by HPCD, their residual activity (RA) decreasing with increasing pressures. The RA of the two PMEs exhibited a fast decrease firstly and reached a constant after a prolonged treatment time; their inactivation kinetics was adequately modelled by a fractional-conversion model. The non-zero RA(A∞ )of the two PMEs was 6–7%, with increasing pressures the kinetic rate constant, k, increased and the decimal reduction time, D, decreased for the HPCD-labile fraction of the two PMEs. The labile fraction of carrot PME was more susceptible to HPCD than that of peach PME; the activation volume, Va , and ZP (the temperature increase needed for a 90% reduction of D) was −1079.37 cm3/mol and 5.80MPa for carrot PME, and −130.51cm3/mol and 48.31MPa for peach PME. [Copyright &y& Elsevier]

Abstract: High pressure carbon dioxide (HPCD) treatment is currently considered as an attractive non-thermal process for preserving food. Industrial application of this technique requires, among others, systematic (quantitative) data on the inactivation of food relevant pathogenic and spoilage microorganisms, and in-depth information on the effect that the composition and the properties of a food matrix have on the inactivation efficacy. The first objective of this study, therefore, is to evaluate and compare the HPCD susceptibility of several food pathogens and spoilage microorganisms under the same treatment conditions. In the second part, the influence of different food components (NaCl, oil, starch, whey protein and emulsifier) and food properties (pH, fluid viscosity and water activity) on the inactivation efficacy of HPCD was determined. For the first aim, a range of Gram-negative and Gram-positive bacteria, yeasts and spores were treated with pressurized CO2 at 10.5 MPa and 35 °C during 20 min. Bacterial susceptibility towards HPCD treatments followed the sequence Gram-negative≈Gram-positive>yeasts>spores and appeared to be related to the acid resistance of the organisms. To study the effect of different food compounds on HPCD inactivation, the reduction degree of Pseudomonas fluorescens was determined in media with and without these components at 10.5 MPa and 35 °C after 5 or 20 min, depending on the tested component. NaCl and the emulsifiers Tween 80 and sucrose stearate enhanced bacterial reduction, while oil reduced the bactericidal efficacy of HPCD. Starch and whey proteins did not influence inactivation. Finally, the influence of pH, fluid viscosity and water activity was investigated by determining the reduction of P. fluorescens at 10.5 MPa and 35 °C in suspensions from which the pH, viscosity and water activity were adjusted with respectively NaOH or HCl, gelatin or polyethylene glycol, and sucrose, NaCl or glycerol. Treatment time depended on the studied food property with 5 min for the pH experiments, while other experiments lasted 20 min. The results indicated that P. fluorescens cells became more sensitive to HPCD treatments at low pH and viscosity. Not water activity but the kind of soluble solute used to lower water activity influenced inactivation. High NaCl-concentrations lead to total inactivation, while sucrose and glycerol strongly protected the cells against inactivation. [Copyright &y& Elsevier]

Isobaric and isothermal semi-logarithmic survival curves of natural microflora in apple juice treated with high-pressure carbon dioxide at 7, 13, and 16 MPa pressures and 35, 50, and 60 °C temperatures were fitted with a nonlinear equation to find the values of the coefficient b( P ), b( T ), n( P ), and n( T ). Profiles of the model parameters were obtained as a function of pressure and temperature. The model fitted with good agreement ( R2 > 0.945), the survival curves. An empirical equation was proposed to describe the combined effects of pressure and temperature. The equation, derived from a power law model, was written in the form: . The proposed model fitted the experimental data well. At 7 MPa and 50 and 60 °C, 13 MPa and 35 and 60 °C, 16 MPa and 35 °C, the model provided log10 reduction residual values (observed value – fitted value) lower than 0.284 showing a good agreement between the experimental and the predicted survival levels. [ABSTRACT FROM AUTHOR]

Abstract: The effect of hydrogen partial pressure on the hydrogenation of limonene in high-pressure carbon dioxide, catalysed by carbon-supported palladium, was studied. Experiments were performed at various hydrogen pressures in the range from 2.5 up to 4.4MPa at a fixed total pressure of 12.5MPa, where the reaction mixture remains biphasic—liquid+gas. In these conditions, the liquid phase volume is expanded in relation to the initial volume of limonene in a fashion that is strongly dependent on the hydrogen to carbon dioxide pressure ratios. Surprisingly, the main factor in the kinetics of hydrogenation turns out to be the concentration (moldm−3) of limonene, which decreases due to the volumetric expansion of the liquid phase when the CO2 pressure increases. [Copyright &y& Elsevier]

Abstract: The change of pressure, temperature and phase during high-pressure carbon dioxide explosion process were investigated. Different initial temperature and pressure conditions were chosen, ranging from 25 to 65°C and 500 to 3000psi covering initial liquid, supercritical and gas phases. Under certain initial conditions with low temperature and high pressure, the depressurization process caused a phase change that increased the release time where the depressurization–time curves did not exponentially decrease. This explosion process was characterized based on total release time, rate of depressurization, and effect of phase change on the rate of depressurization. The temperature change associated with the change of pressure was also discussed. Canola flakes were exploded using chosen initial conditions. Oil extraction from canola flakes using supercritical carbon dioxide was improved after explosion treatment. Explosion at 35°C and 3000psi of initial condition resulted in the highest oil yield. [Copyright &y& Elsevier]

Abstract: Thermal pasteurization is a well known and old technique for reducing the microbial count of foods. Traditional thermal processing, however, can destroy heat-sensitive nutrients and food product qualities such as flavor, color and texture. For more than 2 decades now, the use of high-pressure carbon dioxide (HPCD) has been proposed as an alternative cold pasteurization technique for foods. This method presents some fundamental advantages related to the mild conditions employed, particularly because it allows processing at much lower temperature than the ones used in thermal pasteurization. In spite of intensified research efforts the last couple of years, the HPCD preservation technique has not yet been implemented on a large scale by the food industry until now. This review presents a survey of published knowledge concerning the HPCD technique for microbial inactivation, and addresses issues of the technology such as the mechanism of carbon dioxide bactericidal action, the potential for inactivating vegetative cells and bacterial spores, and the regulatory hurdles which need to be overcome. In addition, the review also reflects on the opportunities and especially the current drawbacks of the HPCD technique for the food industry. [Copyright &y& Elsevier]

Abstract: Sterility is required for medical devices use in invasive medical procedures, and for some situations in the food industry. Sterilization of heat-sensitive or porous materials or devices, such as endoscopes, porous implants, liquid foodstuff, and liquid medicine, poses a challenge to current technologies. There has been a steady interest in using high-pressure carbon dioxide as a process medium for new sterilization technology. Among the potential advantages are that CO2 may sterilize at low temperatures. This paper is a review of the technical and patent literature, including analysis of the microorganisms studied, important operating parameters, and deactivation mechanisms. The current research status and challenges are summarized at the end of this paper. [Copyright &y& Elsevier]

[Display omitted] • HPCD can inhibit the browning of fresh-cut CWC. • After HPCD, PPO and POD in tissues were enhanced during storage. • HPCD changed the structure of phenylalanine ammonia lyase (PAL) from CWC. In this paper, the effect of high-pressure carbon dioxide (HPCD) inhibiting the browning of fresh-cut Chinese water chestnut (CWC) was explored by comparing the differences between damaged and non-damaged tissues. The results showed that the browning of fresh-cut CWC could be effectively inhibited by 2 and 4 MPa treatment, and with these conditions, the microbial load was kept at a low and stable level during the whole storage period. In damaged tissues, the phenylalanine ammonia-lyase (PAL) activity was decreased, thus cutting off the accumulation of naringenin and eriodictyol (only slightly detected at 1 MPa). In non-damaged tissues, the activities of polyphenol oxidase (PPO), peroxidase (POD), and PAL were significantly increased to overcome the treatment stress. The structural change of PAL proved its activity reduction. The mechanism of browning inhibition could be explained by direct inactivation of PAL in damaged tissue and indirect regulation of stress resistance response in non-damaged tissue. [ABSTRACT FROM AUTHOR]

• Seeds were treated after equilibration to a w 0.75 and soaking. • HPCD reduced fungi and bacteria on oats, and barley grains, soy and mung beans. • Salmonella was more resistant than Escherichia coli. • HPCD prevented growth of A. niger and P. roqueforti for 10 d after treatment. • More than 90% of mung beans germinated after treatment. [Display omitted] Decontamination of low a w foods without impairing the food quality is challenging, particularly for sprouting seeds. This study aimed to explore the lethality of high pressure carbon dioxide (HPCD) to Salmonella enterica , E. coli AW1.7, A. niger, P. roquforti , and Fusarium on beans, cereal grains, and ground pepper. The optimal antimicrobial effect of HPCD was achieved by equilibration of the a w to 0.75, followed by soaking in water and treatments with water-saturated CO 2. HPCD reduced the viable cell counts of E. coli and Salmonella by 3–10 log(CFU/g) , and prevented fungal growth during 10 d of incubation. More than 90% of mung beans germinated but the germination of oats was impaired after fungicidal or bactericidal treatments with HPCD. Overall, HPCD can be a promising antimicrobial treatment but treatment parameters need to be optimized for each type of seed. [ABSTRACT FROM AUTHOR]

Clean-label foods have gained a lot of attention since it meets consumers' interests in minimally processed food having a minimal number of ingredients and free from artificial additives. Increased interest in premium quality food products stimulated the integration of high-pressure technologies in food processing compared to conventional thermal processing. While commercial thermal pasteurization is effective in preserving beverages; high pressure-based processing technologies ensure a substantial decrease in microorganisms and spoilage enzymes as well as ensuring minimal impact on the nutrients content and sensory quality. Therefore, this article reviews the potential of high-pressure processing, high-pressure homogenization, ultrahigh-pressure homogenization, high-pressure carbon dioxide/supercritical carbon dioxide, and their updated applications to better preserve the quality of fruit juices and beverages. Pressure-based technologies can assist in reducing the number of ingredients by eliminating the need for certain additives for product stability and preservatives used for food safety and shelf-life extension. Available data highlight important limitations for clean-label food production, represented by the need to establish pressure optimization, microbiological and safe handling in the absence and/or in the presence of a low level of synthetic preservatives. More research is needed for reliable process validation with a focus on process characterization (temperature fields, thermal heterogeneity, and residence time distributions) and sterilization indicators, or mixtures thereof, to implement this promising technology. • Clean label foods are consumer-recognized as natural, premium, and wholesome. • High-pressure based technologies have been investigated to stabilize beverages. • High pressure processing retains freshness as well as nutritional/sensorial quality. • High-pressure technologies are combined with natural additives or other technologies. • Combination of high pressure and CO 2 mitigates the deficiency of using each treatment alone. [ABSTRACT FROM AUTHOR]