Dynamic High-pressure Treatment Research Articles

Fabrication of Whey Protein Isolate-Pectin Nanoparticles by Thermal Treatment: Effect of Dynamic High-Pressure Treatment.

This study investigated the impact of dynamic high-pressure (DHP) treatment on the ability of whey protein isolate (WPI) to form associative complexes with pectin and to form aggregate particles after their subsequent heat treatment. Light scattering showed that DHP treatments disrupted preexisting WPI aggregates and assembled pectin chains. Complexes formed from WPI/pectin mixtures at pH 4.5 were an order of magnitude smaller when formed after DHP treatment, regardless of the degree of esterification. WPI/pectin complexes formed after DHP treatment were more stable against subsequent pH neutralization than complexes formed without DHP treatment, and WPI/high-methoxyl pectin (HMP) complexes had greater stability than WPI/low-methoxyl pectin (LMP) complexes. WPI/pectin particles prepared by thermal treatment of complexes at pH 4.5 were also smaller when prepared after DHP treatment. WPI/HMP particles were stable to subsequent pH neutralization, while WPI/LMP particles became larger after neutralization.

Developments in Plant Proteins Production for Meat and Fish Analogues

In recent years, there have been significant developments in plant proteins production for meat and fish analogues. Some of the key developments include the use of new plant protein sources such as soy, legumes, grains, potatoes, and seaweed, as well as insect proteins, leaf proteins, mushrooms, and microbial proteins. Furthermore, to improve the technological and functional properties of plant proteins, they can be subjected to traditional and unconventional treatments such as chemical (glycosylation, deamidation, phosphorylation, and acylation), physical (pulsed electric fields, ultrasound, high hydrostatic pressure, dynamic high-pressure treatment, and cold plasma), and biological (fermentation and enzymatic modification). To obtain the high quality and the desired texture of the food product, other ingredients besides proteins, such as water, fat, flavors, binders, dyes, vitamins, minerals, and antioxidants, also have to be used. The final product can be significantly influenced by the matrix composition, variety of ingredients, and water content, with the type of ingredients playing a role in either enhancing or constraining the desired texture of the food. There are several types of technologies used for meat and fish analogues production, including extrusion, shear cell technology, spinning, 3D printing, and others. Overall, the technologies used for meat and fish analogues production are constantly evolving as new innovations are developed and existing methods are improved. These developments have led to the creation of plant-based products that have a similar texture, taste, and nutritional profile to meat and fish, making them more appealing to consumers seeking alternatives to animal-based products.

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.

The Effect of High-Pressure Microfluidization Treatment on the Foaming Properties of Pea Albumin Aggregates.

The effect of dynamic high-pressure treatment, also named microfluidization, on the surface properties of thermal pea albumin aggregates (AA) and their foaming ability was investigated at pH 3, 5, and 7. The solubility of albumin particles was not affected by the increase in microfluidization pressure from 70 to 130 MPa. Particle charge depended only on the pH, whereas protein surface hydrophobicity was stable at pH 5, decreased at pH 3, but increased at pH 7 after microfluidization treatment and with the applied pressure. Surface tension of AA measured at air/water interface was favorably affected by the microfluidization treatment at each pH preferentially due to size reduction and increased flexibility of protein particles. The foaming capacity and stability of AA depended on the pH conditions and the microfluidization treatment. The high-pressure treatment had little influence in foaming properties at acidic pHs, probably related to a more compact form of AA at these pHs. At neutral pH, the foaming properties of pea AA were strongly influenced by their surface properties and size associated with significant modifications in AA structure with microfluidization. Changes in albumin aggregate characteristics with pH and microfluidization pressure are also expected to modulate other techno-functional properties, such as emulsifying property. PRACTICAL APPLICATION: Albumins are known for their interesting nutritional values because they are rich in essential amino acids. This fraction is not currently marketed as a protein isolate for human consumption, but can be considered as a potential new vegetable protein ingredient. This document demonstrated that heat treatment or dynamic high-pressure technology can control the foaming properties of this protein for possible use in expanded foods.

Improvement of Orange Juice Preservation by Dynamic High-Pressure Processing

Effects of dynamic high-pressure (DHP) treatments with and without integration with heating on microbial stability, vitamin C concentration, color, sugar content, and pH of orange juice were studied and compared with those of the conventional thermal treatment. Freshly squeezed orange juice was heated at 90C for 1 min or DHP-treated at 205 MPa and 20, 50, 60, or 70C. The DHP treatment at 20C without heating and the treatment at 50C inactivated indigenous mesophilic aerobic microorganisms in orange juice by 4.2 and >7 log CFU/mL, respectively. The DHPtreated juice exhibited brighter color and higher vitamin C concentration and sugar content than the thermally treated juice, regardless of integration with heating. The DHP-treated juice demonstrated brighter color and higher sugar contents than untreated juice and thermally treated juice during storage at 4C for 63 days. The results have demonstrated the potential of applying DHP treatments to pasteurize orange juice with increasing brightness and sugar content of the juice.

With Dynamic High Pressure Treatment Towards a Quasi‐Continuous Inactivation of Microorganisms

AbstractDie Behandlung von Fluiden mit statischem Hochdruck stellt eine schonende Alternative zu konventionellen Entkeimungsprozessen dar. Allerdings handelt es sich um einen kostenintensiven Prozess, dessen Anwendung derzeit auf hochwertige Erzeugnisse limitiert ist. Der Einsatz von dynamischem Hochdruck ermöglicht dagegen eine effizientere Schädigung der Mikroorganismen. Zudem ergibt sich ein quasi‐kontinuierlicher Prozessablauf, wenn die drucklosen Prozessphasen zur Förderung von Fluiden genutzt werden, wodurch die Hochdruckinaktivierung für ein breites Produktspektrum interessant wird.

Changes in the physical properties of xanthan gum induced by a dynamic high-pressure treatment

The effect of microfluidization, a dynamic high pressure treatment, on xanthan gum was investigated in views of enlarging its potential applications. Samples were characterized chemically and physically (molecular weight, intrinsic viscosity, flow behavior and flow induced birefringence). Particular interest was given to the correlation between the level of degradation and aggregate content to the flow behavior and flow-induced birefringence. A mechanism of degradation is proposed: initially, microfluidization reduces the aggregated state of xanthan and may even be able to dissociate the double helical structure into single chains; upon increasing treatment severity, a relatively mild degradation of the main chain can be achieved. Interestingly, samples treated at high ionic strengths were more sensitive to mechanical degradation, arguably since stiffer molecules in the ordered conformation presented a larger exposed surface and thus experienced stronger effective stresses when subjected to the high shear and cavitation forces present in the microfluidization chamber.

Effect of dynamic high-pressure treatment on the interfacial and foaming properties of soy protein isolate–hydroxypropylmethylcelluloses systems

The objective of the work was to study the effect of dynamic high-pressure homogenization (HPH) on the interfacial and foaming properties of soy protein isolate (SP) and surface-active polysaccharides (E4M and E15) with different molecular weight. SP was dispersed with water (2% w/v) together with the polysaccharides (0.3% w/v) and subjected to high-pressure from 0 to 300 MPa, in 100 MPa intervals. After treatment, foam overrun by whipping method, viscosity, particle size distribution and surface pressure at 48 s of drop formation time, of systems were measured. The effect of HPH of these systems on foam overrun was not directly relation with the effect on the surface pressure at short adsorption time. The viscosity decrease may be explained some of the foaming results together with interfacial performance at longer adsorption time than 48 s which depend on the system and level of pressure applied. According to the polysaccharide used in this work, interactions between SP and polysaccharides apparently favour the foam overrun on untreated mixed systems; this effect was promoted using HPH particularly in the case of E15 at 300 MPa. The effect of SP–E4M was less pronounced from the one observed for E15. Thus, the molecular weight of polysaccharides is a very important factor of interaction with soy protein isolate under these conditions of high-pressure homogenization.

Functional properties of whey proteins as affected by dynamic high-pressure treatment

An ultra high-pressure homogenizer was used to treat whey protein isolate solutions (3%, w/w). The treated solutions (up to 300 MPa) were characterised for both physico-chemical properties (particle size distribution, surface hydrophobicity and structural conformation) and functional properties (solubility, foaming stability and interfacial rheology). Dynamic high-pressure treatment did not affect the conformation of the proteins (determined by micro-calorimetry, size-exclusion chromatography and electrophoretic technique). This treatment dissociated large protein aggregates leading to unmasking of the buried hydrophobic groups without affecting protein solubility. Interactions may then occur between these groups that enhance the viscoelasticity of air-water interfaces (assessed by drop tensiometry) and improve foam stability (evaluated by sparging method). Dynamic high-pressure-treated whey proteins showed better foaming and stabilising properties.

Inactivation of food spoilage bacteria and Escherichia coli O157:H7 in phosphate buffer and orange juice using dynamic high pressure

This study aimed to evaluate the potential of dynamic high pressure (DHP) technology to inactivate pathogenic and spoilage microflora in orange juice. Escherichia coli O157:H7 ATCC 35150, Lactobacillus plantarum ATCC 14917, Leuconostoc mesenteroides ATCC 23386 and two orange juice isolates: Saccharomyces cerevisiae and Penicillium ssp. were subjected individually to different DHP treatments. The effectiveness of DHP treatment was first evaluated in phosphate buffered saline (PBS) before application in orange juice samples. The inactivation efficacy of DHP depended on the pressure applied and the number of passes. It was more efficient against Gram-negative strains than Gram-positives. Complete inactivation and 5 log reduction of E. coli O157:H7 were achieved in orange juice at 200 MPa after 5 and 3 passes at 25 °C, respectively. Lower inactivation was obtained with Penicillium ssp. (4 log), S. cerevisiae (2.5 log), L. plantarum (2.3 log) and L. mesenteroides (1.6 log). The gathered results revealed the potential of DHP to inactivate all the tested microorganisms and then, it could constitute a promising alternative technology for cold pasteurization of fruit juices.

Inactivation of Foodborne Pathogens in Milk Using Dynamic High Pressure

Improving the microbiological safety of perishable foods is currently a major preoccupation in the food industry. The aim of this study was to investigate the inactivation of three major food pathogens (Listeria monocytogenes [LSD 105-1], Escherichia coli O157:H7 [ATCC 35150], and Salmonella enterica serotype Enteritidis ATCC [13047]) by dynamic high pressure (DHP) in order to evaluate its potential as a new alternative for the cold pasteurization of milk. The effectiveness of DHP treatment against L. monocytogenes, E. coli O157:H7, and Salmonella Enteritidis was first evaluated in 0.01M phosphate-buffered saline (PBS) at pH 7.2 as a function of applied pressure (100, 200, and 300 MPa) and of the number of passes (1, 3, and 5) at 25°C. A single pass at 100 MPa produced no significant inactivation of the three pathogens, while increasing the pressure up to 300 MPa or the number of passes to five increased inactivation. From an initial count of 8.3 log CFU/ml, complete inactivation of viable L. monocytogenes was achieved after three successive passes at 300 MPa, while 200-MPa treatments with three and five passes completely eliminated viable Salmonella Enteritidis and E. coli O157:H7, respectively. The effectiveness of DHP for the inactivation of these pathogens was compared to that of hydrostatic high pressure (HHP) using the same pressure (200 MPa, single pass at 25°C). In general, two additional log reductions in viable count were obtained with DHP. DHP was less effective against L. monocytogenes and E. coli O157:H7 in raw milk than in PBS. After five passes at 200 MPa, an 8.3-log reduction was obtained for E. coli O157:H7, while a reduction of about 5.8 log CFU/ml was obtained for L. monocytogenes exposed to 300 MPa for five passes. Exposing milk or buffer samples to mild heating (45 to 60°C) prior to dynamic pressurization enhanced the lethal effect of DHP. The inactivation of pathogens also depended on the initial bacterial concentration. The highest reduction was obtained when the bacterial load did not exceed 105 CFU/ml. In conclusion, DHP was shown to be very effective for the destruction of the tested pathogens. It offers a promising alternative for the cold pasteurization of milk and possibly other liquid foods.

Inactivation of lactococcal bacteriophages in liquid media using dynamic high pressure

Abstract Phosphate buffered saline, whey permeate (WP), and milk containing lactococcal bacteriophages c2, sk1 and ul36 (members of the phage species c2, 936, and P335 respectively) were submitted to dynamic high-pressure (DHP) treatments using a laboratory device. Bacteriophage inactivation was evaluated at 25°C, 100 and 200 MPa and 1, 3 or 5 passes. Inactivation was proportional to both pressure and number of passes. In buffer, a maximum inactivation of 5 log cycles was obtained with 200 MPa after 5 passes while the lowest inactivation was obtained with 100 MPa and 1 pass. Lactococcal bacteriophages were more resistant to DHP when spiked in milk and WP with maximum reductions of 2, 2.5 and 3 log cycles for c2, sk1 and ul36 respectively. Bacteriophage inactivation depended also on initial phage concentration. The highest reduction was obtained when the phage load did not exceed 10 4 PFU mL −1 . Heating milk or WP to 50°C prior to DHP treatment did not enhance inactivation. DHP thus seems to be an effective non-thermal method for significant inactivation of lactococcal bacteriophages.