Impact Of High-pressure Treatment Research Articles

Impact of high-pressure treatments on physicochemical and structural changes of reconstituted micellar casein concentrates from bovine and caprine milk: A comparative study

This study investigated the impact of high-pressure processing (HPP) on the physicochemical and structural changes in reconstituted micellar casein concentrates (MCC) sourced from bovine (B) and caprine (C) milk. Applying pressures ranging from 100 to 500 MPa for 30 min at 25 ± 2°C, it was observed that BMCC exhibited a notable increase in soluble minerals and solubility percentages with a simultaneous reduction in particle size and zeta potential compared with CMCC. In BMCC, calcium (Ca) and phosphorus (P) solubility rose from 27.71% and 33.02% to 90.33% and 92.01%, respectively. In CMCC, the solubility of Ca and P increased from 36.12% and 38.29% at 100 MPa to 52.57% and 56.77% at 500 MPa. Additionally, the reduction in particle size was more pronounced in BMCC, with a 53% decrease at 500 MPa, compared with a 19.90% reduction in CMCC. Furthermore, fluorescence intensity, indicative of surface hydrophobicity, decreased in BMCC samples (from 3478 to 2571 a.u.), whereas it increased in CMCC samples (from 2388 to 4058 a.u.) across the same pressure range. Comparative analysis revealed that HP-treated CMCC samples exhibited a decline in α-helix content until the treatment at 300 MPa, followed by an increase post-treatment at 500 MPa. Additionally, a rise in β-sheet structure content was observed, except for the sample treated at 500 MPa, where β-sheet content significantly decreased. These findings suggest that HPP holds promise as a viable technological approach in the dairy sector for enhancing the functional characteristics of CMCC.

Impact of high pressure treatment on shelf life and microbial profile of wild harvested Ascophyllum nodosum and aquacultured Alaria esculenta during storage

Fresh seaweeds, Alaria esculenta and Ascophyllum nodosum, are brown macroalgae species recognised as an excellent source of macro- and micronutrients. Providing novel approaches for ensuring the microbiological safety of this product is important to guarantee the preservation of the nutritional values. In this study, these two species were treated with high pressure, as well as traditional preserving methods (dry salt, and hot water blanching) followed by a storage process to evaluate the effect on the microbiological content and the microbiota profile was investigated after different treatments. High pressure treatments were introduced in order to avoid the salt addition or nutrients loss during conventional seaweed preservation methods.In general, high pressure (500 MPa) treated fresh seaweeds with 4 °C storage temperature still have acceptable total viable counts around 3 log cfu/mL after 30 days. 16S rDNA profiling revealed an average of 3059 operational taxonomic units (OTUs) across all the seaweeds analysed. The top four dominant phyla were Cyanobacteria, Proteobacteria, Firmicutes and Bacteroidota. Cyanobacteria dominated bacteria communities in A. esculenta samples, while Proteobacteria were predominant in A. nodosum samples. In this study, HPP did not cause significant variation of the diversity of microbiome profile but changed the relative abundance of different phyla, including Cyanobacteria, Fermicutes, Bacteriodota and Verrucomicrobia.

Impact of High-Pressure Treatment on Amino Acid Profile, Fatty Acid Compositions, and Texture of Yellowfin Seabream (Acanthopagrus arabicus) Filets

This work describes the optimization of the pressure–time combination for the inactivation of Listeria monocytogenes in fish medium using a wide range of pressure (225–525 MPa) and holding time (5–30 min). Thereafter, the yellowfin seabream (Acanthopagrus arabicus) filets (100 g each) were subjected to high-pressure (HP) treatment at the optimum pressure/time combination, and the impact of HP on the amino acid profile, fatty acid profiles, color, and texture was assessed. Glycine, glutamic acid, and alanine were recorded as the major amino acids, which did not change significantly after pressurization. Conversely, alanine—the leading free amino acid—dropped significantly after treatment. The fatty acid analysis indicated that oleic acid and palmitic acid accounted for 29.88 and 25.59% of the total fatty acids, respectively. Pressurization did not influence the fatty acid profiles, nutritional quality indices, and hardness of yellowfin seabream fish. The color pigments of filets, measured as a* and b*, changed significantly after the treatment. Overall, this work indicates that HP treatment can be utilized to maintain the nutritional quality of seabream filets; however, further research is needed to maintain the visual color of the fish.

High-pressuretreatment of water-filled co-extruded polylactide films: Effect on microstructure, barrier, thermal, and rheological properties.

The impact of high-pressure treatments (450 and 600MPa) on the morphological, thermal, structural, and barrier properties of commercial coextruded polylactide (PLA) packaging films has been explored to evaluate their applicability in food processing. Pouches filled with water as a food simulant were subjected to high-pressure treatment for 15min at ambient temperature. Results indicated no significant changes in the visual appearance, color, integrity, or water barrier properties of the post-process pouches. However, high-pressure treatment affected mechanical property results. Thermal analysis of the film showed endothermic double melting peaks (165.12 and 170.55°C), which did not change with the pressurization; however, the exothermic crystallization peak (118.08°C) varied significantly. Both SEM and AFM micrographs demonstrated that the surface morphology and roughness parameters (arithmetic mean [Sa ] and root mean square height [Sq ]) of the films were significantly affected by the HP treatment, which is further complemented by the FTIR spectra and XRD diffractogram. Melt rheology (175-205°C) of the pressure-treated films showed a significant drop (20-30%) in mechanical rigidity (G') when compared to the untreated sample. Changes in the microstructure/crystallinity in the PLA films were indicated by van Gurp and Palmen plot. PRACTICAL APPLICATION: The results reported here can help to improve the design of the coextruded packaging materials so that it can be successfully implemented to high-pressure processing and high pressure-assisted thermal processing of food.

Improved Physicochemical and Structural Properties of Blueberries by High Hydrostatic Pressure Processing.

The use of high pressure on fruits and vegetables is today widely studied as an alternative to the traditional thermal preservation techniques, with the aim of better preserving nutritional and organoleptic properties. The use of high hydrostatic pressures (400–600 MPa; 1–5 min; room temperature) was tested on the physicochemical and structural properties of blueberries, in comparison to raw and blanched samples. High hydrostatic pressures led to higher tissue damages than blanching, related to the intensity of the treatment. The cellular damages resulted in leakage of intracellular components, such as bioactive molecules and enzymes. As a consequence, among the high pressure treatments, the resulting antioxidant activity was higher for samples treated for longer times (5 min). Pectinmethyl esterase (PME), deactivated by blanching, but strongly barotolerant, was more active in blueberries treated with the more intense high pressure conditions. Blueberry texture was better retained after high pressure than blanching, probably because of the PME effect. Blueberry color shifted towards purple tones after all of the treatments, which was more affected by blanching. Principal component analysis revealed the mild impact of high pressure treatments on the organoleptic properties of blueberries.

Rheological, structural and functional properties of high-pressure treated quinoa starch in dispersions

The impact of high-pressure treatment on the gelatinization of quinoa starch (QS) dispersions was investigated as a function of pressure (300, 450 and 600 MPa for 15 min) and starch to water (S/W) ratio (1:3 and 1:4 w/w). The structural changes of QS were characterized by rheological, DSC, SEM, XRD, and FTIR spectroscopy. The water holding capacity and granules particle size increased significantly with the intensity of pressure. The G′ of the QS gradually improved as a function of pressure and S/W ratio. A complete gelatinization of QS occurred at 600 MPa by breaking down of amylopectin crystallites and transformation to the amorphous state, which was confirmed by rheometry, XRD, and DSC. Additional heat-treatment to pressure-treated samples greatly improved the gel rigidity except for the sample treated at 600 MPa. It can be inferred that the functional properties of QS could be significantly modified/improved with the application a pressure-treatment of 600 MPa.

Impact of high pressure treatment on functional, rheological, pasting, and structural properties of lentil starch dispersions

Lentil starch (LS) dispersions (flour to water 1:4w/w) were subjected to high pressure (HP) treatment at 0.1, 400, 500 and 600MPa for 10min, followed by evaluation on the functional, particle size, rheological, pasting, and structural properties of post-process samples. Water holding capacity of pressurized starch increased with the pressure intensity due to increase in damaged starch. The amount of resistant starch increased from 5 to 6.8% after pressure treatment at 600MPa. An increase in starch granule particle size (196–207μm) was obvious after HP treatment. The lentil starch was completely gelatinized after pressure treatment at 600MPa for 10min as evidenced from differential scanning calorimetry, rheometry, X-ray diffraction (XRD) and scanning electron microscopy observation. The elastic modulus, G′ of lentil starch gel was less frequency dependent, and higher in magnitude at high pressure (>500MPa) than at lower pressure range (≤400MPa). XRD analysis revealed the disappearance of two diffraction peak intensities at 14.86° and 22.82° at 600MPa for 10min, which confirms the transformation of crystalline to amorphous region of lentil starch. Pasting properties were significantly influenced by the pressure treatment especially at 600MPa, resulting in a considerable decrease in peak viscosity, breakdown and final viscosity, and an increase in peak time. It can be inferred that the functional properties of pressure-treated LS are mainly based on the structural destruction of granules.

Impact of high pressure treatment on the available glucose content of various starch types: A case study on wheat, tapioca, potato, corn, waxy corn and resistant starch (RS3)

Abstract In this work the impact of high pressure (HP) processing on the available glucose after enzymatic digestion of various starch types (A-, B-, C- and resistant starch) was investigated. Starch suspensions were HP treated achieving different gelatinization degrees (from 25 to 100%). Starch samples were then freeze-dried and re-suspended in water before further thermal treatment, simulating cooking conditions of ready-to-eat meals. The respective thermally-treated starches were also prepared, achieving 100% gelatinization. The available glucose content was assayed for all starch samples; HP starches that undergone the cooking simulation test released lower amounts of glucose after 2 h of enzymatic digestion in comparison to the thermally-gelatinized samples. Moreover, among the HP pre-treated starches, waxy corn starch released the lowest amount of glucose. Further, the impact of freeze-drying on the enzymatic digestion was investigated. It was noticed that dehydration causes a slight increase in the levels of the released glucose after 120 min of digestion. Industrial relevance High pressure is an established nonthermal processing technology that can be industrially used to optimize existing products or allow development of novel products of high quality. The specific study shows that HP technology favors starch gelatinization and can be used to contribute to the production of starch based ready-to-eat meals characterized by low levels of released glucose.

Effect of high pressure - low temperature processing on composition and colloidal stability of casein micelles and whey proteins

The aim of this study was to identify the impact of high pressure treatments at sub-zero temperatures (high pressure - low temperature; HPLT) on milk proteins. Whey protein solutions, micellar casein dispersions and two mixtures (micellar caseins:whey proteins, 80:20 and 20:80, w/w) were pressure treated (100–600 MPa) at pH 7.0 or 5.8 at −15 °C, −35 °C and ambient temperature. Solubility data showed that whey proteins could only be affected by HPLT treatments at pH 7.0 if caseins were present, while effects could be induced at pH 5.8 without the presence of caseins. The caseins formed on the one hand large aggregates (flocs) and on the other hand the solubility was increased by the creation of smaller micelles. The formation of flocs could only be observed for HPLT treated samples, which indicates the formation of different protein interactions in milk protein based samples compared with common HP treatments.

Impact of high pressure treatment and intramuscular fat content on colour changes and protein and lipid oxidation in sliced and vacuum-packaged Iberian dry-cured ham

The effect of high hydrostatic pressure (HHP) (600MPa) and intramuscular fat content (IMF) on colour parameters and oxidative stability of lipids and proteins in sliced vacuum-packaged Iberian dry-cured ham during refrigerated storage (120days at 2°C) was investigated. Several studies have investigated the influence of HHP on lipid oxidation of meat products. However, its effects on protein carbonylation, as also the influence of IMF content on this carbonylation are poorly understood. HHP treatment had a significant effect on lean lightness after 0 and 120days of storage while IMF content increased lightness and yellowness over time. Regarding oxidative stability, the effect of HHP treatment depended on IMF content samples with a high IMF having greater lipid instability while samples with a low IMF underwent more protein carbonylation.

Impact of high pressure treatments on the physicochemical properties of a sulphur dioxide-free white wine during bottle storage: Evidence for Maillard reaction acceleration

Abstract The impact of high hydrostatic pressure (HHP) treatments on physicochemical characteristics of sulphur dioxide-free white wines was studied during one year of bottle storage. For this purpose, a white wine was produced without the addition of sulphur dioxide (SO 2 ) and was pressurized at two pressure conditions, 500 and 425 MPa, for 5 min at 20 °C. A wine with 40 ppm of SO 2 and a wine with no preservation treatment were used as controls. Pressurized wines showed, after one year of storage, a more brownish color (higher a * and b * values and lower L *) and a slightly lower antioxidant activity and total content of phenolic compounds compared to the unpressurized wines (wine with SO 2 and wine without any treatment). These results, together with the lower content of free amino acids ( e.g. 87% less of serine) and higher content of furans ( e.g. 10 fold higher of 2-furfural), presented in the pressurized wines after nine months of storage, lead to propose an effect of HHP treatments in the acceleration of Maillard reactions occurring during the wine storage period. Industrial relevance HHP might be used in winemaking as an alternative process for preservation of wine, which can lead to the production of a wine with reduced amounts of SO 2 . Until now, the physicochemical and sensorial properties of wine have been studied only after the pressure treatment, without ever having references on the influence of the treatment in wine properties during storage. Then, the effect of HHP on the physical–chemical characteristics on long term storage of wine is still largely unknown. This work shows that HHP treatments accelerate Maillard reactions during the white wine storage period. This reaction should be taken into consideration in the implementation of HHP treatments to wine conservation as alternative to SO 2 .

Effect of high pressure and heat treatments on black tiger shrimp (Penaeus monodon Fabricius) muscle protein

Abstract Application of high pressure, a minimal processing, has gained interest particularly in extending the shelf-life or modifying the texture of seafood, especially in shrimp. However, pressurization may render the products with different texture as compared with their fresh and heated counterparts. Therefore, the impact of high-pressure treatment (200, 400, 600, and 800 MPa for 20 min at 28°C) on black tiger shrimp muscle proteins in comparison with heat treatment (100°C for 2 min) was investigated. Differential scanning calorimetry thermogram indicated that high pressure up to 200 MPa for 20 min induced the denaturation of myosin and actin with subsequent formation of a network stabilized by hydrogen bond. An electrophoretic study revealed that the sample pressurized at 800 MPa or heated at 100°C was also stabilized by disulfide bond. L*, a*, and b* values, compression force, and shear force increased with increasing pressure (p < 0.05). The heat-treated sample had higher L*, a*, b*, and shear force (toughening) than the pressurized and fresh samples (p < 0.05). Pressure at different levels had no effect on weight loss (p ≥ 0.05). However, a weight loss of 27.89% was observed in the heat-treated sample. Proteolytic activity of crude extract from the pressurized sample at 200 to 600 MPa did not differ from that of the fresh sample (p < 0.05). Nevertheless, the activity in the heated sample and that of the pressurized sample at 800 MPa decreased, indicating the inactivation of endogenous proteases in the muscle.

Impact of high pressure treatment on the structure of montmorillonite

The modification of sodium montmorillonite after a high pressure pasteurization treatment was followed by X-ray diffraction, FTIR spectroscopy and thermogravimetric analysis. Regardless of the treatment intensity (300 and 800MPa), the structure of montmorillonite was clearly modified. Such changes should be taken into consideration when binging montmorillonite–polymer nanocomposites into contact with food.

Characterization of High-Hydrostatic-Pressure Effects on Fresh Produce Using Chlorophyll Fluorescence Image Analysis

High hydrostatic pressure has the potential to affect food-related enzymes and microorganisms while retaining the produce’s characteristic properties. Although many studies on effects of high pressure on quality attributes of fruit and vegetables have been published, experimental results on the impact of high-pressure treatment on the physiological activity of products are rare. To characterize changes of the samples fast and noninvasive methods as well as a sensitive biological model system are required for this purpose. In this study, fresh lamb’s lettuce (Valerianella olitoria Poll.) was used as a model produce. For each treatment, two leaves were carefully inserted to small plastic pouches, sealed and then subjected to pressure (up to 7.5 min at 200 MPa) or thermal treatment (up to 1 min at 50°C). Chlorophyll fluorescence imaging was applied to measure the local and temporal dynamics of the physiological postprocessing effects. Measurements of the maximum photochemical efficiency F v/F m allows the immediate evaluation of photosynthetic activity as an indicator for cell and tissue vitality. Thermal treatment at pressure below 125 MPa and temperatures lower than 45°C showed minor fully reversible effects but a pronounced decline in the maximum photochemical efficiency was obtained after pressure treatment of 150 MPa and temperatures of 45°C or higher values. These changes were irreversible within 24 h of recovery time. Above these thresholds, high pressure and heat treatment may not be applicable for mild processing of highly perishable fresh produce. Chlorophyll fluorescence analysis has been proven to be a valuable tool for the rapid and comprehensive evaluation of postharvest processing of green perishables.

Effect of high pressure on some physicochemical properties of several native starches

Abstract The impact of high pressure treatments (HPT) on some physicochemical properties of normal corn, waxy corn, wheat, and potato starches were studied. Three high pressure treatments were applied: HPT1 (740–880 MPa from 5 min to 2 h), HPT2 (960–1100 MPa for 24 h) and HPT3 (1500 MPa for 24 h). Using differential scanning calorimetry (DSC), it was found that the gelatinization temperature of starch was lowered by 3.0–6.6 °C after high pressure treatment and the corresponding gelatinization enthalpy was also reduced. In addition, these changes were irreversible and maintained during storage at 25 °C for up to 6 months. However, the birefringence of native and high pressure treated starch was not visually different in polarized light. For starches of same biological origin, their X-ray diffraction patterns were also similar. Using scanning electron microscopy (SEM), it was revealed that the high pressure treatments altered the shape of starch granules and changed their surface appearance.

High pressure treatment of reduced-fat Mozzarella cheese: Effects on functional and rheological properties

A study was undertaken to determine the effects of high pressure (HP) treatment on the rheological and cooking properties and appearance of reduced-fat Mozzarella cheese (RFMC). RFMC of approx. 10.7% fat was manufactured at pilot-scale. A portion of the cheeses (HP) were tempered at 21 °C for 16 h on day 1, high pressure-treated at 400 MPa for 5 min at 21 °C and then stored at 4 °C for 35 days. The remainder of the cheeses (C) were also tempered at 21 °C for 16 h and then stored at 4 °C for 35 days. There was a significant interactive effect of HP treatment and storage time on non-expressible serum per gram protein (NESP, i.e., an index of protein hydration in the cheese), the levels of which were significantly higher in HP than in C cheeses at day 2 of storage. HP treatment also significantly decreased the L* (reduced whiteness), a* (increased greenness) and b* (reduced yellowness)-values after storage for 1 day, but no effect was observed after 75 days storage. However, HP treatment did not significantly effect composition, pH, proteolysis, rheological properties of the unheated cheese or flowability and stretchability of the heated RFMC. Industrial relevance Mozzarella cheese has become one of the most prominent cheese varieties. Low fat cheeses are desirable and sought after but fat reduction adversely effects texture and cooking properties. Since HP treatment of milk has shown to improve texture of low fat cheeses it was relevant to investigate the impact of HP treatment on appearance and on rheological and cooking behaviour of reduced-fat Mozzarella cheese. Although time dependent changes were observed no clear trends or advantages could be attributed to HP treatment.