High Pressure Processing Research Articles

High pressure processing at different hydration levels as a tool to enhance rice bran stability and techno-functionality.

High-pressure processing (HPP) enhances food safety and shelf life by inactivating microorganisms and preserving food quality, yet its effectiveness in low-humidity environments has not been evaluated. This study investigated the effects of HPP at 500MPa for 15min across varying hydration levels (15, 30, 60, 77%) on rice bran (RB), aiming to identify microbial effectiveness, besides techno-functional and physicochemical properties. HPP effectively reduced mesophilic bacteria, molds and yeast of RB at>15% hydration level, achieving reductions of up to 4 logarithmic cycles in the latter, nearing the detection limit of the method. However, it did not significantly impact spore inactivation. HPP treatment of≥30% hydrated RB induced particles aggregation and a honeycomb formation. The interaction between hydration and HPP treatment significantly affected the distribution of total dietary fibers, with an increase in soluble dietary fiber from 8.73g/100g to 11.03g/100g after HPP treatment at 15% hydration level. Protein solubility was enhanced by hydration (15, 30 and 60%), and peroxide values decreased after HPP treatment at low hydration (≤30%) but increased when applied to high hydrated (>30%) RB. Emulsifying activity decreased upon HPP treatment of highly hydrated RB (≥60%), but more stable emulsions were achieved after HPP, regardless of the hydration level. Therefore, this study highlights the potential of HPP as a sustainable approach to enhance the utilization of rice bran in food applications, addressing existing knowledge gaps regarding its processing under different moisture conditions.

Development of High-Pressure Sliding Process for Grain Refinement with Enhanced Properties in Metallic Materials

Development of High-Pressure Sliding Process for Grain Refinement with Enhanced Properties in Metallic Materials

Near-Infrared Spectroscopy as a Tool for the Traceability Control of High-Quality Iberian Dry-Cured Meat Products

Near-infrared spectroscopy (NIRS) was evaluated to trace the high hydrostatic pressure (HHP) processing and preservation temperature (4 °C vs. 20 °C) over the course of a long term in vacuum-packaged Iberian dry-cured tenderloin (Iliopsoas et psoas minor). Spectra were obtained from a total of 298 samples, without opening the package, using a handheld MicroNIRTM 1700 OnSite-W microspectrophotometer (908.1 nm–1676.2 nm) (VIAVI Solutions Inc., United States). The discriminant models were developed by means of partial least squares-discriminant analysis (PLS-DA). The models obtained were capable of correctly classifying more than 60% of the samples according to their HHP processing, while almost 100% of the samples were correctly classified according to the temperature at which the samples were preserved. Thus, NIRS could help to support the traceability of treatments that represent a high added value to the product, such as HHP in premium Iberian dry-cured products.

High-Pressure Extraction Techniques for Efficient Recovery of Flavonoids and Coumarins from Flower Seeds

The extraction of bioactive compounds, such as flavonoids and coumarins, from natural sources has gained significant attention due to their potential health benefits. This review aims to explore the application of high-pressure extraction processes, particularly supercritical fluid extraction (SFE) and pressurized liquid extraction (PLE), for obtaining flavonoids and coumarins from flower seeds. These techniques offer a greener, more efficient alternative to conventional extraction methods, minimizing the use of harmful solvents and improving the yield and purity of the target compounds. Flower seeds, a rich source of bioactive molecules, are an underutilized reservoir for these valuable compounds. For example, seeds from plants such as Calendula officinalis (calendula) and Helianthus annuus (sunflower) are rich in flavonoids and coumarins. The proposed review will examine the influence of extraction parameters—such as temperature, pressure, solvent choice, and extraction time—on the yield and quality of flavonoids and coumarins. This review aims to provide a comprehensive understanding of high-pressure extraction methods and optimize protocols for the efficient, sustainable extraction of flavonoids and coumarins from flower seeds.

Newly identified SpoVAF/FigP complex: the role in Bacillus subtilis spore germination at moderate high pressure and influencing factors.

High-pressure-induced spore germination has been discovered for more than half a century, but the signal transduction pathway of the process still needs to be refined. In this study, for the first time, we revealed the role of the newly identified SpoVAF/FigP complex in high-pressure-induced spore germination, as well as the factors influencing its function in this process. The new findings in this work not only enhance the theoretical understanding of spore germination mechanisms under high pressure but also pave the way for developing novel strategies to inactivate spores during high-pressure food processing, a technology that is gaining popularity in the food industry as a promising non-thermal preservation method.

Changes in Microbial Safety and Quality of High-Pressure Processed Camel Milk.

High-pressure processing (HPP) is used as a non-thermal approach for controlling microbial viability. The purposes of this study were to (i) establish the decimal reduction times (D-values) for pathogenic bacteria during 350 MPa HPP treatment,; (ii) evaluate the impact of 350 MPa HPP on total plate count (TPC), yeasts and molds (YM), and lactic acid bacteria (LAB) in camel milk; (iii) investigate the behavior of several spoilage-causing bacteria during storage at 4 °C and 10 °C for up to 10 d post-HPP treatment; and (iv) assess the effect of HPP on the protein degradation of camel milk. The D-values for L. monocytogenes, E. coli O157:H7, and Salmonella spp. were 3.77 ± 0.36 min, 1.48 ± 0.08 min, and 2.10 ± 0.13 min, respectively. The HPP treatment decreased pathogenic microorganisms by up to 2 to 3 log cfu/mL (depending on treatment conditions). However, HPP reduced TPC, YM, and LAB by <1 log cfu/mL, regardless of the length of pressure exposure. HPP treatment, even at extended holding times, did not significantly alter either the proteolytic activity or casein micelle structure in camel milk. This study highlights HPP as a promising non-thermal technique for enhancing the microbiological safety of camel milk.

Pomegranate Juices: Analytical and Bio-Toxicological Comparison of Pasteurization and High-Pressure Processing in the Development of Healthy Products.

Two different produced and packaged commercial typologies of pomegranate juice were analyzed for their physicochemical, nutritional, and biological properties. The effects of classical pasteurization (PJ) and high-pressure processing (HP), applied during the productive cycle, were evaluated through several advanced analytical methods, such as CIEL*a*b* colorimetry, HPLC-DAD, DI-ESI-MS and MS/MS, and NMR analyses. Moreover, the exerted biological activity of the two pomegranate juices was monitored through Total Phenolic and Total Flavonoid Contents, antiradical, antioxidant and chelating activity. The potential inhibition of key enzymes of degenerative processes (cholinesterases, tyrosinase) and diabetes (amylase, glucosidase), the allelopathy toward Cichorium intybus, Dicondra repens, and Diplotaxis tenuifolia, and the in vivo toxicity on brine shrimp were also evaluated. The two different applied processing techniques analyzed impacted the bioactive compound's preservation differently, modifying the phytocomplex profile. HP significantly degrades punicalins and punicalagins, better preserving anthocyanins, if compared to PJ's impact. Sensory qualities, antioxidant activity, enzymatic inhibition, and ecotoxicological potential were differently impacted by the two applied processes. The obtained results can be beneficial for finding the optimal processing conditions that balance microbial safety with nutritional value preservation, contributing to the development of healthy pomegranate juice products.

Prospects of cold plasma in enhancing food phenolics: analyzing nutritional potential and process optimization through RSM and AI techniques.

Consumption of plant-based food is steadily increasing and follows an augmented trend owing to their nutritive, functional, and energy potential. Different bioactive fractions, such as phenols, flavanols, and so on, contribute highly to the nutritive profile of food and are known to have a sensitivity toward higher temperatures. This limits the applicability of traditional thermal treatments for plant products, paving the way for the advancement of innovative and non-thermal techniques such as pulsed electric field, microwave, ultrasound, cold plasma, and high-pressure processing. Among these techniques, cold plasma would be an operative choice in plant-based applications due to their higher efficacy, greenness, chemical exclusivity, and quality retention. The efficiency of the plasma process in ensuring the bioactive potential depends on several factors, such as feeding gas, input voltage, exposure time, pressure, and current flow. This review explains in detail the optimization of process parameters of the cold plasma technique, ensuring greater extractability or retention of total phenols and antioxidant potential. Response surface methodology (RSM) is one of the common techniques involved in the optimization of these course factors. It also covers the convention of artificial intelligence-based methods, such as artificial neural networks (ANN) and genetic algorithms (GA), in evaluating the data on process parameters. The review critically examines the strengths of each optimization tool in determining the optimal process parameters for maximizing phenol retention and antioxidant activity. The ascendancy of these techniques was mentioned in the studies regarding fruit, vegetables, and their products, and they can also be applied to other food products.

Introduction and Applications of Ultra High Pressure in Food Technology

In recent years, ultra high pressure (UHP) technology has gained high prominence in the food processing industry, which can meet the growing requirement of consumers of high-quality food. This article reviews the history of the ultra high pressure (UHP) process and introduces the principles connected with UHP processing and the methods we used in UHP processing. Also, this paper talks about applications like extracting bioactive peptides and inactivating bacteria through recent examples. Finally, this study combines specific research results to demonstrate the advantages of UHP, it is an advanced processing technique responding to market requirements, and is quite promising for the area of storing perishable food products. UHP treatment can also be widely applied in products rapid freezing to get high-quality food with longer shelf life in order to meet consumers requirements. In the future, some more advanced concepts and cutting-edge technologies, such as computer modeling can be applied to the field of UHP processing.

Ester-Based Lubricant and Anti-Leidenfrost Additive Solutions on Aluminum High-Pressure Die-Casting Applications

The high-pressure die-casting process is growing since it is a cost-effective solution in the production of lightweight parts for a variety of industries. Nevertheless, the harsh working conditions of the die lead to premature failing and poor quality of the produced parts. Lubricants are applied to cooling the die surface and create a protective film to minimize die wear. However, the high temperature of the die during the casting production makes it difficult for the lubricant to reach the die surface due to the Leidenfrost effect. In this study, the effectiveness of newly developed ester-based lubricants designed to address Leidenfrost phenomenon in high-pressure die-casting is evaluated at laboratory and pilot plant scale. The new lubricants are based on the same ester solution; however, one of them includes a specially formulated anti-Leidenfrost additive to optimize performance at the temperature ranges typically encountered in industrial aluminum high-pressure die-casting processes. The results show a correlation between lubricant heat-transfer capability and aluminum adhesion. Additionally, a pilot plant methodology for testing newly formulated lubricants has been established while the experimental methodology developed for assessing heat-transfer capability is validated as a rapid and cost-effective approach for evaluating lubrication alternatives for high-pressure die-casting applications. Finally, the efficiency of environmentally friendly ester-based lubricants for high-temperature applications has been demonstrated.

Impact of microwave processing and high pressure processing on omega-3 fatty acid enriched snack of microalgae (Nannochloropsis sp)-cocoa balls

Abstract This study investigates the development of a functional snack, NSP (Nannochloropsis sp.)-cocoa balls, enriched with omega-3 fatty acids, utilizing two advanced processing methods: microwave processing and high-pressure processing (HPP). The primary objective was to assess the efficiency of these techniques in preserving nutritional value, particularly omega-3 content, while maintaining desirable sensory qualities over a 12-day storage period. Microwave processing was found to partially retain omega-3 fatty acids but resulted in increased firmness and faster oxidation due to moisture loss during heating. In contrast, HPP effectively preserved omega-3 content and maintained the original texture and sensory appeal of the NSP-cocoa balls. The even distribution of omega-3 fatty acids in HPP-treated samples enhanced their resistance to oxidation, contributing to greater stability. Sensory evaluations identified the HPP-treated cocoa balls, specifically those prepared using Recipe 4, as the most preferred for their texture and superior nutritional profile. Furthermore, food safety analyses confirmed the safety of these snacks for consumption throughout the storage period. This comprehensive study highlights HPP as a superior processing method for developing functional foods that balance nutrient preservation with sensory quality, offering a promising approach for creating health-focused, shelf-stable snacks.

Effect of thermal and high-pressure processing on the quality and shelf life of coconut-cashew nut milk beverage

Effect of thermal and high-pressure processing on the quality and shelf life of coconut-cashew nut milk beverage

Characterization and Sliding Wear Behavior of Low-Pressure Cold-Spray Al-Al2O3 and Al-Al2O3/TiN Composite Coatings

Low-pressure cold-spray (LPCS) aluminum is widely used for coating depositions in various engineering applications but is limited by its low hardness and poor wear resistance. To improve these properties, ceramic particles are added to form metallic matrix composites (MMCs). High-pressure processes can achieve effective MMC coatings but are costly and energy intensive. LPCS has been studied to develop an Al-based MMC at a lower cost. To ensure the adaptation of developed LPCS coating in engineering applications, the behavior of the coating under certain loads needs to be established. This study investigates the sliding wear behavior, friction characteristics, hardness, and microstructure of Al-Al2O3 and Al-Al2O3/TiN composite coatings deposited using LPCS at 1 MPa and 450 °C. The effect of adding 25 wt% TiN to the Al-Al2O3 composite was explored. Although the addition of TiN did not significantly enhance the hardness of the coating, SEM analysis revealed notable differences in wear behavior between the two coatings. The Al-Al2O3/TiN composite exhibited better wear resistance, which was attributed to the reduced formation of powdery wear debris and improved crack suppression. These findings highlight the potential of TiN reinforcement to enhance the tribological performance of LPCS aluminum-based coatings, offering a promising solution for improving wear resistance in engineering applications.

Modification of black soybean (Glycine max(L.)merr.) residue insoluble dietary fiber with ultrasonic, microwave, high temperature and high-pressure, and extrusion.

Recent studies have emphasized the modification of Insoluble Dietary Fiber (IDF) to enhance its physicochemical properties and functional performance. This study systematically examined the effects of ultrasonic treatment, microwave irradiation, high-temperature and high-pressure processing, and screw extrusion on the physicochemical characteristics, in vitro antioxidant activity, and adsorption capacities of High-Purity Insoluble Dietary Fiber (HPIDF) derived from black bean residues. Although these physical modifications did not alter the functional group composition or crystalline structure of HPIDF, they significantly enhanced its porosity, water-holding capacity (WHC), oil-holding capacity (OHC), and adsorption capacities for glucose, cholesterol, bile salts, and metal ions. Notably, HPIDF treated under high-temperature and high-pressure conditions exhibited the highest adsorption capacities: 9.86mmol/g for glucose, 8.69mg/g (pH2) and 9.69mg/g (pH7) for cholesterol, 0.183g/g (pH2) and 0.127g/g (pH7) for sodium cholate, and 0.699mg/g (pH2) and 0.774mg/g (pH7) for Cr2+.

Determination of Time Required for 5 Log Reduction of Foodborne Pathogens by High Hydrostatic Pressure Processing in Foods

ABSTRACTHigh hydrostatic pressure (HHP) is a nonthermal preservation technology for inactivating foodborne pathogens and spoilage organisms. The commercial use of HHP is generally performed at pressures of 400–600 MPa, at ambient initial temperature for less than 6 min. Moreover, at least 5 log10 reduction of target pathogen is required for safe HHP‐treated foods. Literature data of foodborne pathogens (Escherichia coli, Listeria monocytogenes, Salmonella spp., etc.) were collected based on these ranges and information (P: 400–600 MPa, T: 4°C–25°C, t ≤ 6 min) and were described by the reparameterized Weibull model to find times required for 5 log10 of target pathogens together with their confidence limits. Results indicated that pressure values of even 400–450 MPa were sufficient to obtain 5 log10 reduction for times ≤ 6 min for high acid foods. Furthermore, 600 MPa treatment, which is generally used by the industry, is a robust and efficient application as holding times less than 5 min were generally enough to obtain 5 log10 reduction for most of the pathogens. Nevertheless, for some pathogens in milk, such as E. coli and Stapylococcus aureus, higher holding times of &gt; 10 min were necessary which was not practical for a commercial HHP application. Conditions for microbial HHP studies generally do not match with industrial HHP applications. However, data selection criteria in this study were based on commercial applications. Information provided in this study would be beneficial for researchers as well as for HHP food processors for designing future studies and HHP treatments.

Dynamic characteristics of gas-liquid type compressed CO2 energy storage system with focus on high-pressure liquid energy release process

Dynamic characteristics of gas-liquid type compressed CO2 energy storage system with focus on high-pressure liquid energy release process

Growth of MoS2 Nanosheets on Brush-Shaped PI-ZnO Hybrid Nanofibers and Study of the Photocatalytic Performance.

The design and preparation of advanced hybrid nanofibers with controllable microstructures will be interesting because of their potential high-efficiency applications in the environmental and energy domains. In this paper, a simple and efficient strategy was developed for preparing hybrid nanofibers of zinc oxide-molybdenum disulfide (ZnO-MoS2) grown on polyimide (PI) nanofibers by combining electrospinning, a high-pressure hydrothermal process, and in situ growth. Unlike simple composite nanoparticles, the structure is shown in PI-ZnO to be like the skeleton of a tree for the growth of MoS2 "leaves" as macro-materials with controlled microstructures. The surface morphology, structure, composition, and photocatalytic properties of these structures were characterized using scanning electron microscopy, X-ray diffraction, X-ray photoelectron spectroscopy, and UV-vis spectroscopy. The ultra high-volume fraction of MoS2 can be grown on the brush-shaped PI-ZnO. Decorating ZnO with nanosheets of MoS2 (a transition metal dichalcogenide with a relatively narrow band gap) is a promising way to increase the photocatalytic activity of ZnO. The hybrid nanofibers exhibited high photocatalytic properties, which decomposed about 92% of the methylene blue in 90 min under visible light irradiation. The combination of MoS2 and ZnO with more abundant surface-active sites significantly increases the spectral absorption range, promotes the separation and migration of carriers, and improves the photocatalytic characteristics.

Predicting transient performance of a heavy-duty gaseous-fuelled engine using combined phenomenological and machine learning models

Decarbonizing long-haul goods transportation poses a substantial challenge. High-efficiency natural gas (NG) engines, which retain the efficiency of a diesel engine but reduce the carbon content of the fuel, offer substantial potential for near-term greenhouse gas (GHG) reductions. A fast-running model that can predict engine performance, GHG and air pollutant emissions is critical to assessing this approach for different applications and vehicle drivetrain configurations. This paper presents the development, validation and application of an engine system model that adapts GT-SUITE™’s phenomenological DI-Pulse predictive model to predict the performance and emissions of a 6-cylinder NG engine using a high pressure direct-injection combustion process. The model includes the engine air exchange system, enabling the prediction of the engine and in-cylinder conditions and overall performance over transient drive cycles. The engine model with a fixed set of calibration parameters captures the complex high-pressure direct injection combustion process and generates time-resolved parameters that are fed into a coupled machine learning model to predict emissions, including nitrogen oxide (NOx) and methane (CH4) emissions. While the 1-D model’s predictions for CH4 were not accurate, coupling the 1-D engine model with a machine learning model has been shown to substantially improve the estimation of CH4 emissions and allow accurate prediction of engine total GHG emissions over different duty cycles. The model has been validated using transient engine dynamometer data and is then applied to assess performance and emissions over several regulatory and real-world long-haul drive cycles. The model showed an average error of less than 5% in steady operation. Cumulative errors of NOx and CH4 emissions in studied cycles were also less than 10%. The results showed that CH4 share in total GHG emissions ranges from 0.2% to 1.4% over various drive cycles. By predicting engine performance and emissions, the developed combined model has considerable potential for use in engine evaluation studies, especially when combined with new technologies across different duty cycles.

Prevalence of Antibiotic Resistance Genes in Differently Processed Smoothies and Fresh Produce from Austria.

Plant-derived foods are potential vehicles for microbial antibiotic resistance genes (ARGs), which can be transferred to the human microbiome if consumed raw or minimally processed. The aim of this study was to determine the prevalence and the amount of clinically relevant ARGs and mobile genetic elements (MGEs) in differently processed smoothies (freshly prepared, cold-pressed, pasteurized and high-pressure processed) and fresh produce samples (organically and conventionally cultivated) to assess potential health hazards associated with their consumption. The MGE ISPps and the class 1 integron-integrase gene intI1 were detected by probe-based qPCR in concentrations up to 104 copies/mL in all smoothies, lettuce, carrots and a single tomato sample. The highest total (2.2 × 105 copies/mL) and the most diverse ARG and MGE loads (16/26 targets) were observed in freshly prepared and the lowest prevalences (5/26) and concentrations (4.1 × 103 copies/mL) in high-pressure-processed (HPP) smoothies. BlaCTX-M-1-15 (1.2 × 105 c/mL) and strB (6.3 × 104 c/mL) were the most abundant, and qacEΔ1 (95%), blaTEM1 (85%), ermB and sul1 (75%, each) were the most prevalent ARGs. QnrS, vanA, sat-4, blaKPC, blaNDM-1 and blaOXA-10 were never detected. HPP treatment reduced the microbial loads by ca. 5 logs, also destroying extracellular DNA potentially encoding ARGs that could otherwise be transferred by bacterial transformation. The bacterial microbiome, potential pathogens, bacterial ARG carriers and competent bacteria able to take up ARGs were identified by Illumina 16S rRNA gene sequencing. To reduce the risk of AMR spread from smoothies, our data endorse the application of DNA-disintegrating processing techniques such as HPP.

Quantifying the Impact of High-Pressure Processing on the Phenolic Profile, Antioxidant Activity, and Pollen Morphology in Honey.

Honey can benefit from non-thermal processing techniques such as high-pressure processing (HPP) to improve its quality and bioactivity. This study investigated the impact of HPP (600 MPa for 5, 10 and 15 min) on honey's quality, including the levels of hydroxymethylfurfural (HMF), antioxidant activity, total phenolic content (TPC) and phenolic profile. HPP treatment did not significantly affect HMF or TPC levels but led to selective changes in the phenolic profile. Despite a reduction in certain phenolic compounds content, HPP for 5 and 15 min caused a significant increase the antioxidant activity (DPPH) of honey from the mean value of 41.8% to value of 45.4 and 49.6%, respectively. On the other hand, HPP for 10 min did not change the antioxidant activity of tested honey. A 27.5% reduction in equatorial diameter of pollen grains was observed after HPP combined with temperature at 75°C, suggesting improved release of bioactive compounds. The content of specific phenolic compounds, including caffeic acid, p-coumaric acid, sinapic acid, naringin, kaempferol, and the TPC, significantly affected the DPPH activity. The increment in the antioxidant activity of HPP honey may be attributed to selective changes in the content of certain phenolic compounds and improved their extraction from pollen grains.