High Pressure Pretreatment Research Articles

Effect of high hydrostatic pressure pretreatment on physicochemical properties, bioactive components and antioxidant activities of dehydrated yam slices

High hydrostatic pressure (HHP) treatment has been widely used to achieve the desired safety and quality of food products during the past two decades. In this work, effects of HHP (100–600 MPa) pretreatments on physicochemical properties, bioactive components and antioxidant activities of dehydrated yam slices were studied. The results indicated that HHP pretreatments dramatically improved the hardness, crispness, integrity ratio, and total color change of the dehydrated yam slices, while significantly inhibited their rehydration ratio when the pressure was ≥200 MPa. According to the results of scanning electron microscopy (SEM), optical microscopy (OM), and polarized optical microscopy (POM), HHP could induce the indentations and cracks of partly starch granules surface, but without any starch gelatinization. Compared with the control sample, higher total polyphenols compounds (TPC) and allantoin content were observed in the HHP pretreated samples, and the 200 MPa pretreated sample had the highest TPC and allantoin which reached 0.45 mg GAE/g and 5.47 mg/g dry weight, respectively. Furthermore, the antioxidant analysis showed that 100 and 200 MPa pretreatment could effectively enhance the antioxidant capacity of the yam slices. The above results suggested that HHP pretreatment, especially under 200 MPa, could be an appropriate assist for preparation of high-quality dehydrated yam slices.

Effect of high-pressure pretreatment on enzymatic hydrolysis of a mixture of rainbow trout (Oncorhynchus mykiss) and Atlantic salmon (Salmo salar) rest raw material

IntroductionFish rest raw material generated from the fish processing industry may be a useful resource for recovery of added value compounds. The application of non-thermal novel technologies can improve the extraction. High-pressure processing (HPP) has long been used for the preservation and extension of the shelf life of seafood. It also constitutes a promising technology for the increased recovery of valuable compounds, such as lipids and proteins. The objective of this study was to assess the yield and the chemical composition of the fractions obtained after enzymatic hydrolysis on a mixture of Atlantic salmon (Salmo salar) and rainbow trout (Oncorhynchus mykiss) rest raw material pretreated by high-pressure (HP).MethodsSix different pretreatments were applied prior to enzymatic hydrolysis; 600 MPa x 8 min, 600 MPa x 4 min, 400 MPa x 8 min, 400 MPa x 4 min, 200 MPa x 8 min, 200 MPa x 4 min.Results and discusssionThese applied pretreatments did not yield higher oil extraction compared to the control. However, the fish protein hydrolysates (FPH) contained higher amount of protein when compared to the FPH obtained from the control.

Gamma radiation vs high pressure pretreatment on physicochemical characteristics of rice bran hydrolysate

This study investigated the effect of using gamma radiation and high-pressure processing as pretreatment, to consider the structural and amino acid composition changes in rice bran hydrolysate (RBH). The extraction yield and degree of hydrolysis of the irradiated sample were greater than those of the pressurized and control samples, which radiation at 10 kGy gave 31 % yield. Protein content of the control was the highest at 36.1 %, with 32.4 % in pressurized sample at 500 MPa. Control had the highest concentration of total and branched-chain amino acids, with a value of 25,834 mg/100g. Before and after extraction, the microstructure changed visibly and protein agglomeration can be significantly induced by applying a high-pressure. Therefore, this study showed the potential of using both pretreatment methods prior to enzymolysis extraction, with radiation producing more extract. High-pressure produced more protein content, but neither method produced any difference in amino acid content.

Effect of high pressure pretreatment on the inhibition of ice nucleation and biochemical changes in pork loins during supercooling preservation

In this study, the effect of high pressure (HP) pretreatment on the stability of pork loins during supercooling (SC) preservation was investigated, and the freshness and postmortem metabolism of pork loins preserved by SC was evaluated. Based on the differential scanning calorimetry (DSC), the peak enthalpies of 200 MPa treatment were lower than those of 50 MPa treatment (P < 0.05). For the nuclear magnetic resonance (NMR) relaxometry, extramyofibrillar water in pork loins was decreased with increasing intermyofibrillar water at >100 MPa (P < 0.05). Compared to unpressurized control all HP treatment had less α-helix structure while random coil was dominated from the Fourier transform infrared (FTIR) spectroscopy (P < 0.05). A 200 MPa was selected to estimate the relationship between HP pretreatment and stability of SC preservation of pork loins. The HP-treated pork loins showed high stability during SC preservation under the relatively low temperature algorithm. Compared to fresh control, HP pretreatment caused physicochemical changes of pork loins which did not recover even after 2 weeks of preservation. Nevertheless, HP followed by SC preservation was able to reduce property changes better than pork loins preserved by normal refrigeration. According to the analyses of transmission electron microscopy (TEM), the HP pretreatment influenced the postmortem biochemical metabolism of pork loins, however, it did not affect the freshness and quality parameters of pork loins due to the subsequently applied low preservation temperature of SC. Therefore, this study demonstrated that moderate HP pretreatment was a potential pretreatment for SC preservation of pork loins.

Modelling and Evaluation of the Effect of Pulsed Electric Fields and High Pressure Processing Conditions on the Quality Parameters of Osmotically Dehydrated Tomatoes

This study explores the osmotic dehydration (OD) of fresh-cut cherry tomatoes through the application of Pulsed Electric Fields (PEF) and High-Pressure (HP) pre-treatments. Untreated, PEF-treated (1.8 kV/cm, 0–300 pulses), and HP-treated (0–600 MPa, 5 min) tomatoes were subjected to osmotic dehydration at 35 °C for up to 3 h. The results reveal that a 100-pulse PEF treatment and HP treatment at 600 MPa yielded optimal outcomes in terms of both OD enhancement (with effective moisture diffusion coefficients of 7.91 · 10−10 m2/s for PEF and 7.40 · 10−10 m2/s for HP-treated tomatoes compared to 5.17 · 10−10 m2/s for untreated samples) and product acceptability (achieving overall acceptance scores between 7 and 8). Applying PEF (100 pulses) and HP (600 MPa) pre-treatments reduced the water activity (aw) to 0.887 and 0.760, respectively, after 3 h of OD, compared to aw = 0.923 for untreated OD samples. The selection of these pre-treatment conditions enabled effective dehydration and quality retention, extending the shelf life by up to 40 days under chilled storage.

Impact of high pressure pre-treatment and hot water extraction on chemical properties of crude polysaccharide extract obtained from mushroom (Volvariella volvacea).

An examination of the process of extracting crude polysaccharides from Volvariella volvacea solely through hot water treatment (HWE) at 60, 80, and 100°C and through an approach involving high pressure processing (HPP) at 200, 400, and 600MPa followed by HWE. The physiological properties of the polysaccharides could be explained by the structural analysis performed via FT-IR spectroscopy and NMR spectroscopy, which revealed the extract composition of the protein-bound polysaccharides connected by β-glycosidic bonds. Under the extraction conditions investigated in this current study, the recommended extraction condition was a combination of HPP (600MPa, 10min) and HWE (60°C, 2h). This condition gave high crude polysaccharide yields (with a 2-12% increase), and β-glucan content (with a 15-20% increase) without disrupting the β-glycosidic bond, as compared to using HWE alone. High pressure extraction could be an alternative technique for reduced extraction temperatures of active compounds from mushrooms.

Biotransformation of wheat proteins with Lactobacillus sp. following high hydrostatic pressure pre-treatment to reduce gluten immunoreactivity

The effect of high hydrostatic pressure (HHP, 50–300 MPa, 5 min, 18 °C) on the biotransformation of wheat proteins with Lactobacillus acidophilus or L. sanfranciscensis was studied. Increasing the pressure from 50 to 150 MPa before sourdough fermentation did not change the size of the bacterial population, but it increased the endoproteolytic activity of Lactobacillus enzymes, degree of protein hydrolysis and decreased the concentration of gliadins and gluten immunoreactivity. Fermentation after pressurization at 150 MPa reduces to 44.0 ± 0.1 and 25.6 ± 1.1%, the immunoreactivity of proteins in sourdough obtained by fermentation with L. acidophilus and L. sanfranciscensis, respectively. Further increasing the pressure from 150 to 300 MPa resulted in the reduction of bacterial growth, reduction of endoproteolytic activity, degree of protein hydrolysis, gliadin degradation and gluten immunoreactivity. Sourdough treatment at 250 and 300 MPa increased the antigen concentration compared to the control samples. The fermentation of sourdough with L. acidophilus and L. sanfranciscensis, following increasing pressurization, resulted in an increase in the β-sheets and a decrease in the α-helix structure of the protein. Applying the pressure of 250 and 300 MPa changes the conformation of gluten, and reduced significantly activity of peptidases of Lactobacillus strains, thereby increasing protein immunoreactivity.

High pressure-assisted enzymatic hydrolysis promotes the release of a bi-functional peptide from cowhide gelatin with dipeptidyl peptidase IV (DPP-IV) inhibitory and antioxidant activities

The process of generating functional peptides from cowhide gelatin is challenged by inefficient enzymatic hydrolysis. In this study, the researchers attempted to enhance the hydrolysis and potential functional properties of the peptides by subjecting the cowhide gelatin to high-pressure treatment (200, 300, and 400 MPa) for 20 min, followed by enzymatic hydrolysis. The highest 2,2-diphenyl-1-picrylhydrazyl (DPPH) radical scavenging activity, 2,2′ azinobis(3 ethylbenzothiazoline 6 sulfonic acid) (ABTS) radical scavenging activity, and DPP-IV inhibitory activity of the hydrolysate were obtained at 200 MPa, accompanied with an increase in the content of hydrophobic, acidic, and basic amino acids (P < 0.05). Correspondingly, the high-pressure pretreatment (200 MPa) reduced the thermal stability, particle size, and morphological integrity of cowhide gelatin, with a corresponding increase in the exposure of hydrophobic regions. Altogether, these results indicated that appropriate high-pressure-assisted enzymatic hydrolysis reinforced the release of bi-functional peptides by modifying the structure of cowhide gelatin.

Role of some structural features in EPS from microalgae stimulating collagen production by human dermal fibroblasts

ABSTRACTExopolysaccharides (EPS) from the microalgae Porphyridium cruentum, Chrysotila dentata, Pavlova sp., Diacronema sp., Glossomastix sp., Phaeodactylum tricornutum, and Synechococcus sp. were isolated and depolymerized. First, EPS were submitted to a high pressure pre-treatment step, followed by a solid acid-catalyzed hydrolysis step carried out in a batch or recycle fixed-bed reactor, using a strong acidic cation-exchange resin. Twenty-eight different EPS forms were thus obtained. After characterization of their main structural features (weight- and number-averaged molecular weight, polydispersity index, sulfate and uronic acid contents), we investigated the structure–function relationship of their pro-collagen activity. We found that native microalgae EPS were able to inhibit until 27% of human matrix metalloproteinase-1 (MMP-1) activity while the depolymerized forms were able to enhance collagen production by two different human fibroblast lines, used as cell models due to their major role in dermal collagen biosynthesis. The most active EPS forms, obtained by depolymerization in the recycle fixed-bed reactor of D. ennorea and Glossomastix sp. EPS, led to 390% increase in collagen production. Finally, principal component (PCA) and Pearson analyses indicated that MMP-1 inhibition was strongly correlated to the sulfate group content of EPS whereas collagen production by fibroblasts was mostly related to their proportion of low molecular weight polysaccharides (<10 kDa). Uronic acid content of EPS was also shown essential but only if the size of EPS was reduced in the first place. Altogether, these results gave new insights of the dermo-cosmetic potential of microalgae EPS as well as the key parameters of their activity.

Role of high hydrostatic pressure pretreatment on the formation of electrospun nanofibers from soy protein isolate/polyvinyl alcohol

In this research, the characteristics of the high hydrostatic pressure (HHP)-treated soy protein isolate (SPI) solutions as well as HHP-treated SPI (HSPI) electrospun fibers were comprehensively studied for the first time. For this purpose, surface tension, electrical conductivity, viscosity, zeta potential, and secondary structure of HSPI solutions at different ratios were investigated. Also, differential scanning calorimetry (DSC), Fourier-transform infrared (FTIR) spectroscopy, X-ray diffraction (XRD), and scanning electron microscopy (SEM) of HHP-treated and non-treated SPI: PVA nanofibers were thoroughly compared. HHP denaturation reduced the size of nanofibers by 50–100 nm, diminished ordered structures and crystallinity of nanofibers, increased their melting point and induced hydrogen bonding between amino groups of denatured SPI and hydroxyl groups of PVA. These findings open a new horizon in the successful application of non-thermal energies in the electrospinning process to achieve appropriate fibers at nanoscale.

Effect of high pressure pretreatment on the drying characteristics of the beetroot (Beta vulgaris) cubes

Effect of high pressure pretreatment on the drying characteristics of the beetroot (Beta vulgaris) cubes

High-pressure microwave-assisted pretreatment of softwood, hardwood and non-wood biomass using different solvents in the production of cellulosic ethanol

BackgroundPretreatment is an indispensable stage of the preparation of lignocellulosic biomass with key significance for the effectiveness of hydrolysis and the efficiency of the production of cellulosic ethanol. A significant increase in the susceptibility of the raw material to further degradation can be attained as a result of effective delignification in high-pressure conditions. With this in mind, a method of high-pressure pretreatment using microwave radiation and various solvents (water, 40% w/v NaCS, 1% v/v H2SO4, 1% w/v NaOH or 60% v/v EtOH with an addition of 1% v/v H2SO4) was developed, enabling the acquisition of biomass with an increased susceptibility to the process of enzymatic hydrolysis. The medium obtained in this way can be used for the production of cellulosic ethanol via high-gravity technology (lignocellulosic media containing from 15 to 20% dry weight of biomass). For every type of biomass (pine chips, beech chips and wheat straw), a solvent was selected to be used during the pretreatment, guaranteeing the acquisition of a medium highly susceptible to the process of enzymatic hydrolysis.ResultsThe highest efficiency of the hydrolysis of biomass, amounting to 71.14 ± 0.97% (glucose concentration 109.26 ± 3.49 g/L) was achieved for wheat straw subjected to microwave-assisted pretreatment using 40% w/v NaCS. Fermentation of this medium produced ethanol concentration at the level of 53.84 ± 1.25 g/L. A slightly lower effectiveness of enzymatic hydrolysis (62.21 ± 0.62%) was achieved after high-pressure microwave-assisted pretreatment of beech chips using 1% w/v NaOH. The hydrolysate contained glucose in the concentration of 91.78 ± 1.91 g/L, and the acquired concentration of ethanol after fermentation amounted to 49.07 ± 2.06 g/L. In the case of pine chips, the most effective delignification was achieved using 60% v/v EtOH with the addition of 1% v/v H2SO4, but after enzymatic hydrolysis, the concentration of glucose in hydrolysate was lower than in the other raw materials and amounted to 39.15 ± 1.62 g/L (the concentration of ethanol after fermentation was ca. 19.67 ± 0.98 g/L). The presence of xylose and galactose was also determined in the obtained fermentation media. The highest initial concentration of these carbohydrates (21.39 ± 1.44 g/L) was observed in beech chips media after microwave-assisted pretreatment using NaOH. The use of wheat straw after pretreatment using EtOH with an addition of 1% v/v H2SO4 for the preparation of fermentation medium, results in the generation of the initial concentration of galactose and xylose at the level of 19.03 ± 0.38 g/L.ConclusionThe achieved results indicate a high effectiveness of the enzymatic hydrolysis of the biomass subjected to high-pressure microwave-assisted pretreatment. The final effect depends on the combined use of correctly selected solvents for the different sources of lignocellulosic biomass. On the basis of the achieved results, we can say that the presented method indicates a very high potential in the area of its use for the production of cellulosic ethanol involving high-gravity technology.

Insights into high hydrostatic pressure pre-treatment generating a more efficient catalytic mode of maltogenic α-amylase: Effect of multi-level structure on retrogradation properties of maize starch

Maltogenic α-amylase (MA) is an enzyme used to retard starch retrogradation in the baking industry. However, sometimes it exhibits low efficiency which may restrict the enzymatic application. This study investigates the effects of using High hydrostatic pressure (HHP) as a pre-treatment to promote MA catalysis. The results showed that HHP resulted in more indentations and fissures of the starch granules promoting the susceptibility of MA. While MA treatment alone introduced short malto-oligosaccharide chains with degree of polymerization (DP) 1–5, the combined HHP-MA treatment exhibited a higher proportion of DP 1–9, but a lower proportion of DP 13–24. Furthermore, when increasing the pressure, the ratio of α-1,6 to α-1,4 glycosidic bonds increased in the MA-treated starch. MA modification on the HHP-pretreated starch showed increasing gelatinization temperature and enthalpy, while it had a reverse impact on long-term retrogradation enthalpy due to the shortening of the outer chains of amylopectin. LF-NMR was applied to analyze the water mobility and compartmentalization in starch gel systems after 1- and 7-days storage. Compared with single MA-treated system, HHP-MA treated starches showed no significant changes in the value of the transverse relaxation times, but less amount of bulk water was detected due to higher amounts of soluble small oligosaccharides. In conclusion, HHP pre-treatment combined with MA could improve the water holding properties of retrograded starch gels and that HHP prior to MA catalysis provides an efficient alternative method to modify starch-based food products with anti-stalling properties.

Effects of high hydrostatic pressure on physicochemical and functional properties of soybean protein isolate

Impacts of high hydrostatic pressure (HHP) pretreatment on the physicochemical, functional and antioxidant properties of soybean protein isolate (SPI) were investigated. Changes in the secondary and tertiary structures were determined by Fourier transform infrared spectra and fluorescence spectra. The particle sizes reduced from 217.20 nm to 192.70 nm while the zeta potential increased. It’s revealed by scanning electron microscopy that the HHP treatment could result in the formation of large aggregation, leaving the SPI with irregular and uneven surface. Moreover, hollow spheres were also observed in SPI by means of dynamic and static light scattering. As a result, the foaming capacity of HHP-treated SPI and antioxidant activity of the HHP-treated SPI hydrolysates were improved significantly.

Impacts of the Dynamic High-Pressure Pre-Treatment and Post-Treatment of Whey Protein Aggregates on Their Physicochemical Properties and Emulsifying Activities.

The impacts of dynamic high-pressure (DHP) pretreatment and post-treatment (100 MPa) on the physicochemical and functional properties of whey protein isolate (WPI) aggregates formed by thermal treatment were investigated in this study. When WPI aggregates were formed by thermal treatment, the size of the aggregates formed with the DHP pretreated WPI was smaller than that of the aggregates formed with the original WPI. The size of the WPI aggregates formed by thermal treatment decreased with DHP post-treatment. The conformational parameters (ζ-potential, surface hydrophobicity, and intrinsic fluorescence intensity) of the WPI subjected to DHP pretreatment were not significantly influenced by thermal treatment. However, DHP post-treatment affected these parameters for the WPI aggregates formed during thermal treatment because of dissociation caused by intense shear and cavitation forces during DHP treatment. The emulsifying activity index (EAI) of the WPI aggregates slightly improved with DHP treatment, but its order had little effect on the magnitude of the EAI increase. DHP pretreatment or post-treatment can modulate the conformational structures and the physicochemical properties of protein aggregates.

Impact of high hydrostatic pressure (HHP) pre-treatment drying cashew (Anacardium occidentale L.): drying behavior and kinetic of ultrasound-assisted extraction of total phenolics compounds

Impact of high hydrostatic pressure (HHP) pre-treatment drying cashew (Anacardium occidentale L.): drying behavior and kinetic of ultrasound-assisted extraction of total phenolics compounds

Sustainable extraction of polyphenols from millet using switchable deep eutectic solvents

In this study, polyphenols were extracted from millet with a high hydrostatic pressure (HHP) pretreatment combined with switchable deep eutectic solvent (DES) extraction. The antioxidant activity of the extract was evaluated, and the switchable DESs were recycled and reused. HHP pretreatment destroyed the cell structure of millet to facilitate the extraction of polyphenols. The grinding-assisted extraction was used as the extraction method by taking switchable DES (octanoic acid-linalool) as the extraction solvent and β-cyclodextrin as the auxiliary extraction reagent. The hydrophilic DES was switched to the hydrophobic DES to recover millet polyphenols. The hydrophobic DES was recycled and switched to the hydrophilic DES for extracting new millet samples. After being reused five times, the yield of millet polyphenols using recycled DESs did not decrease significantly. In conclusion, HHP pretreatment combined with switchable DES extraction is considered as a green, efficient, and sustainable method for bioactive compounds.

Effect of high pressure pretreatment on myrosinase-glucosinolate system, physicochemical and bacterial properties during fermentation of brine-pickled radishes

The myrosinase-glucosinolate system, physicochemical properties, and bacterial community were profiled during fermentation of high hydrostatic pressure (HHP) pretreated brine-pickled radishes; traditionally brine-pickled radishes were utilised as the control. Scanning electron microscopy (SEM) analysis revealed that 300 MPa pretreatment promoted brine infiltration in radish cells and damaged cellular microstructures, which activated the myrosinase-glucosinolate system. The conversion of glucosinolate (GLs) to isothiocyanates (ITC) increased and significantly enhanced the raphasatin and sulforaphene contents of pickled radish. However, 600 MPa pretreatment suppressed myrosinase activity. HHP pretreatment altered the natural radish bacterial communities by reducing the total bacterial and lactic acid bacteria counts. Lactobacillus spp. became the dominant bacterial genus within 15 d of fermentation. However, the destruction of cellular structures by HHP pretreatment also significantly decreased hardness and caused the dissolution of amino acids and TTA into brine. This caused reduced amino acid and TTA contents compared to the control group, as well as decreases in pH. HHP pretreatment suppressed the growth of spoilage bacteria (e.g. Pseudomonas, Staphylococcus, and Shewanella genera). This study provides new insight into the potential applications of HHP treatment in pickling, as it demonstrates that HHP can increase the ITC conversion rate of pickled radish, modify its physiochemical characteristics, and decrease microbial risk. Therefore, HHP is a promising preprocessing technique to be used for pickle manufacturing industry.

Structural and functional properties of alginate obtained by means of high hydrostatic pressure-assisted extraction

The effects of the high hydrostatic pressure (HPP) pre-treatment on the alginate extraction were seen to greatly depend on the recalcitrant nature of two algae species. Alginates were deeply characterized in terms of composition, structure (HPAEC-PAD, FTIR, NMR, SEC-MALS), functional and technological properties.The pre-treatment significantly increased the alginate yield in the less recalcitrant A. nodosum (AHP) also favoring the extraction of sulphated fucoidan/fucan structures and polyphenols. Although the molecular weight was significantly lower in AHP samples, neither the M/G ratio nor the M and G sequences were modified. In contrast, a lower increase in alginate extraction yield was observed for the more recalcitrant S. latissima after the HPP pre-treatment (SHP), but it significantly affected the M/G values of the resulting extract. The gelling properties of the alginate extracts were also explored by external gelation in CaCl2 solutions. The mechanical strength and nanostructure of the hydrogel beads prepared were determined using compression tests, synchrotron small angle X-ray scattering (SAXS), and cryo-scanning electron microscopy (Cryo-SEM). Interestingly, the application of HPP significantly improved the gel strength of SHP, in agreement with the lower M/G values and the stiffer rod-like conformation obtained for these samples.

Supercritical CO2 Extract from Microalga Tetradesmus obliquus: The Effect of High-Pressure Pre-Treatment.

High-pressure pre-treatment followed by supercritical carbon dioxide (ScCO2) extraction (300 bar, 40 °C) was applied for the attainment of the lipophilic fraction of microalga Tetradesmus obliquus. The chemical profile of supercritical extracts of T. obliquus was analyzed by ultra-high-performance liquid chromatography–high-resolution mass spectrometry with electrospray ionization (UHPLC-ESI-HRMS). Moreover, the impact of ScCO2 on the microbiological and metal profile of the biomass was monitored. The application of the pre-treatment increased the extraction yield approximately three-fold compared to the control. In the obtained extracts (control and pre-treated extracts), the identified components belonged to triacylglyceroles, fatty acid derivatives, diacylglycerophosphocholines and diacylglycerophosphoserines, pigments, terpenes, and steroids. Triacylglycerols (65%) were the most dominant group of compounds in the control extract. The pre-treatment decreased the percentage of triacylglycerols to 2%, while the abundance of fatty acid derivatives was significantly increased (82%). In addition, the pre-treatment led to an increase in the percentages of carotenoids, terpenoids, and steroids. Furthermore, it was determined that ScCO2 extraction reduced the number of microorganisms in the biomass. Considering its microbiological and metal profiles, the biomass after ScCO2 can potentially be used as a safe and important source of organic compounds.