High-pressure Homogenization Treatment Research Articles

Effect of High Pressure Treatment on Interfacial Properties, Structure and Oxidative Stability of Soy Protein Isolate-Stabilized Emulsions

The effect of high pressure homogenization (HPH) treatment (40 to 200MPa) on the structure, interfacial properties and oxidative stability of soy protein isolate emulsions were investigated. After HPH process, emulsifying activity (EAI) and emulsion stability (ESI) could be improved by 114% and 125%, percentage of protein adsorbed to oil-in-water emulsions significantly improved when the pressure was not more than 160 MPa. SDS-PAGE showed that the HPH caused more low molecular mass subunits as the samples were treated below 160 MPa. FTIR traced the changes of four conformations in the secondary structure. Within a suitable pressure range, the apparent viscosity increased with the increasing of pressure, which reflected shear thinning; rheological measurement of emulsions showed G'>G'', G' and G'' both increased significantly with frequency increasing; emulsions treated by HPH had better oxidative stability. This paper suggested the HPH was a useful method for preparation the highly viscous and stable emulsions.

Effects of high pressure homogenization on rheological properties of rice starch

ABSTRACTGelatinized starch paste was prepared by gelatinizing rice starch at 95 °C in a water bath. Then, the rice starch (both normal rice starch and waxy rice starch) paste was subjected to high-pressure homogenization at homogenizing pressure of 20, 40, 60, 80 MPa. The rheological properties (including shear stress versus shear rate, apparent viscosity versus shear rate and thixotropy) of starch paste were studied. The high-pressure homogenization was able to improve the flow properties of starch paste. The shear stress increased with the increasing shear rate, and the Power law equation was capable of fitting the shear stress versus shear rate quite precisely. High-pressure homogenization treatment sharply decreased the thixotropy of starch paste, and the thixotropy of rice starch (both NRS and WRS) paste decreased with the increasing homogenous pressure.

Structure and functionalities changes in high-pressure homogenized clam protein isolate

High-pressure homogenization (HPH) under 0–100 MPa was performed to treat clam protein isolate (CPI) for three cycles. Results indicated that HPH treatment resulted in significant improvements of CPI functional properties. Absolute zeta potential, emulsifying activity index, and emulsion stability index significantly increased by 19.37 mV, 33.26 m2/g, and 14.00 min after HPH under 100 MPa. Solubility of CPI dramatically increased by 70.8% under 80 MPa. Foaming ability and foaming stability increased by 33.8% and 14.4% under 60 MPa. HPH resulted in significant decrease in percentage of both α-helix and β-turn, but percentage of β-sheet greatly improved as the pressure increased. Free sulfhydryl and surface hydrophobicity increased but fluorescence intensity decreased significantly after HPH treatment. Improvements of these functionalities were due to protein structure changes and particle size reduction. This study demonstrated that HPH has the potential to improve functional properties of shellfish protein through modifying protein structure. Practical applications A nonthermal processing technique using HPH can improve functional properties of CPI, including solubility, emulsifying properties, and foaming properties. Therefore, HPH can be potentially used to process shellfish proteins to improve their functional properties.

Recovery of brines from cheesemaking using High-Pressure Homogenization treatments

The effect of High-Pressure Homogenization treatments at 150MPa on the viability of microbial flora in natural and spiked brines for cheesemaking was assessed. The microbial reductions increased with the number of passes through the homogenization valve (with or without temperature control) and this behavior was well described by a linear equation. Higher microbial reduction rates were observed when temperature was not controlled during processing. In this case, temperature progressively increased because of HPH process up to 75 °C after 11 passes. The killing effect of HPH treatments was caused by the synergic action of physical and mechanical stresses suffered by the product during the passage through the homogenization valve. These effects were further enlarged when temperature increased as number of passes also increased. The HPH treatments allowed an almost total inactivation of most of the native contaminants just after 5 passages, and the same treatment was effective against potentially pathogenic and spoilage microorganisms in the spiked brines, causing the total inactivation of L. monocytogenes.

Effect of ultrasounds and high pressure homogenization on the extraction of antioxidant polyphenols from lettuce waste

Abstract The possibility to exploit ultrasound (US) and high pressure homogenization (HPH) to obtain ethanolic antioxidant extracts from lettuce waste was studied. The application of US (400 W, 24 kHz) for 120 s led to polyphenol extraction yield (81 μg/mL) and antioxidant activity (101 μg TE/mL) significantly higher than those obtained by traditional solid-liquid extraction at 50 °C for 15 min. Despite the intense cell rupture effect, the application of HPH pre-treatments resulted in 25% lower phenolic yields as compared to US solely, possibly due to the 40% activation of polyphenoloxidase (PPO) upon HPH treatment. Industrial relevance The waste generated by fresh-cut processing of lettuce poses environmental and economic issues to companies, leading to the need for alternative strategies for its management. US can be successfully exploited as time-saving extraction procedure for obtaining antioxidant extracts from lettuce waste.

Synthesis of stabilized hydroxyapatite nanosuspensions for enamel caries remineralization.

The aim of this study was to develop and evaluate a method for synthesizing a stable suspension of hydroxyapatite nanoparticles and to test its efficacy for remineralizing carious enamel lesions. Hydroxyapatite (HA) particles were synthesized using wet chemistry. Synthesized particles were introduced into a high-pressure homogenizer (5-10 homogenization passes at 15 000 psi) in the presence of different stabilizers. Size and distribution of the resultant particles were determined using dynamic light scattering (DLS). The morphology and composition of the nanoparticles were determined using scanning electron microscopy (SEM) and energy-dispersive X-ray spectroscopy (EDS). Subsequently, artificial lesions were treated with HA nanosuspension plus artificial saliva or a fluoride-containing artificial saliva only. Visual analysis and quantification of the lesion mineral density before and after remineralization were performed using microcomputed tomography. DLS and SEM results confirmed the formation of nonagglomerated HA nanoparticles (20-40 nm) following high-pressure homogenization treatment. Quantitative evaluation of the lesions showed that remineralization of the lesion with hydroxyapatite nanosuspension led to a significantly higher level of mineral gain compared to the control group (P < 0.05). High-pressure homogenization is an effective method for facile preparation of a stable suspension of hydroxyapatite nanoparticles. Treatment of artificial lesions with nonagglomerated spherical HA nanoparticles improves the remineralization of enamel lesion.

High-Pressure Homogenization Pretreatment before Enzymolysis of Soy Protein Isolate: the Effect of Pressure Level on Aggregation and Structural Conformations of the Protein.

The high-pressure homogenization (HPH) treatment of soybean protein isolate (SPI) before enzymatic hydrolysis using bromelain was investigated. Homogenization pressure and cycle effects were evaluated on the enzymatic degree of hydrolysis and the antioxidant activity of the hydrolysates generated. The antioxidant activity of SPI hydrolysates was analyzed by 1,1-dipheny-2-picrylhydrazyl (DPPH). The sizes and structures of the SPI-soluble aggregate after HPH treatment were analyzed using dynamic and static laser light scattering. The changes in the secondary structure, as measured by Fourier transform infrared spectroscopy (FTIR) and the macromorphology of SPI, were measured by scanning electron microscope (SEM). These results suggested that the HPH treatment (66.65%) could increase the antioxidant activities of the SPI hydrolysates compared with the control (54.18%). SPI hydrolysates treated at 20 MPa for four cycles obtained higher DPPH radical-scavenging activity than other samples. The control was predicted to be a hard sphere, and SPI treatment at 10 MPa was speculated to be Gaussian coil, polydisperse, and then the high-pressure treated SPI became a hollow sphere. Changes in the secondary structures showed protein aggregate formation and rearrangements. The image of SPI varied from a globular to a clump structure, as observed by the SEM. In conclusion, combining HPH treatment and enzymolysis could be an effective way to improve the antioxidant activity of the SPI.

Determination of powder flow properties of skim milk powder produced from high-pressure homogenization treated milk concentrates during storage

The aim of this study was to determine effects of high-pressure homogenization (HPH) treatment to milk concentrates on powder flow properties of skim milk powders (SMP). For this purpose, SMP samples were produced from skim milk concentrates which were HPH treated at 0 (control), 50, 100 and 150 MPa. SMP samples were stored 180 days at 20 and 40 °C and caking, cohesion and powder flow speed dependency test (PFSD) were performed using a Powder Flow Analyzer. HPH treatment decreased cohesion and caking properties of SMPs. At the 0. day, cake strength of SMPs from HPH treated concentrates varied from 0.43-2.70 mN.m, whereas cake strength of SMP-0 (control) was 8.20 mN.m. Cohesion index (CI) of samples ranged from 6.80-15.74 mm during storage. Based on CI, SMPs from HPH treated concentrates showed free and easy flowing flow behavior during storage at 20 and 40 °C. In addition, cohesion index at four speeds indicated that SMP from HPH treated concentrates were more flowable at even lower flow speeds then SMP-0. PFSD test verified that all SMP samples showed more free-flowing characteristics with increasing flow speeds. Flow stability of samples ranged from 0.95-1.15 and also flow stability of SMP-0 increased during storage at both 20 and 40 °C. The results revealed that HPH treatment to milk concentrates could improve powder flow properties of skim milk powders.

Microalgae disruption techniques for product recovery: influence of cell wall composition

Microalgae are one of the most promising feedstocks for the production of commodity and value-added products. However, the use of microalgae as a feedstock is hampered by the process economics and sustainability. Overall sustainability can be improved by employing energy-efficient cell disruption and recovery processes to maximize the extraction of desired compounds from microalgal biomass. Most often, extraction processes are conducted with solvents using untreated, chemically treated, or mechanically treated cells. However, microalgal cell walls are sometimes structurally robust, complex, and chemically diverse and high energy inputs or large quantities of chemicals are required to extract products from within the cell. Various chemical, biological, and physical techniques have been employed to disrupt the cell walls from a variety of microalgae species, and these include the use of surfactants, autoclave, microwave, sonication, bead milling, enzymatic hydrolysis, high-pressure homogenization, and steam treatments. Although the cell wall structure is important for product recovery, it is often not considered when selecting the most appropriate disruption method. In this study, the cell wall structure of selected microalgae species and the effectiveness of various cell wall disruption techniques on product recovery are reviewed. It was concluded that future research must focus on developing an understanding of the relationship between cell wall disruption mechanisms and cell wall composition and structure, as well as optimizing the energy consumption of the disruption technique. This approach would enable the design of innovative cell wall disruption techniques for an enhanced product recovery.

Characterization of thermal, mechanical and hydration properties of novel films based on Saccharomyces cerevisiae biomass

Abstract Characterization of films made of Saccharomyces cerevisiae biomass was performed so as to better understand their properties. The treated yeast biomass, named HTH, was prepared by subsequent steps including a first homogenization, heat treatment and final homogenization. Glycerol was added as plasticizer and films were evaluated using different techniques to measure mechanical behaviour, thermal properties and water sorption. Temperature of maximum decomposition rate was found near 300 °C, while the gradually disappearance of amide II band (1543 cm−1) occurred from 225 °C, identified by FTIR spectra of residues of thermally treated films by TGA. A glass transition at 64.5 ± 3.0 °C and two low energy endotherms at 61.2 ± 2.3 and 106.1 ± 0.7 °C were determined in completely dehydrated films without glycerol. When glycerol content was increased the glass transition temperature was shifted to lower values, a maximum elongation of 12% was reached, Young's modulus decreased from 88 to 9 MPa and the water uptake of films raised from 0.49 to 0.79 g H2O/g of dry matter. The characterization of yeast biodegradable films provided evidence of their properties for a potential future use in packaging industry. Industrial relevance The development of biodegradable films based on yeast biomass carries many advantages to the food industry, such as, the possibility of using commercial pressed baker's yeast or an industrial residue from brewing industry, the use of a low-cost sources and the application of environmentally friendly procedures. The methodologies applied for the development of the film forming dispersion, high pressure homogenization and thermal treatment, are able to be scaled-up to an industrial level.

Effects of high-pressure homogenization on functional properties and structure of mussel (Mytilus edulis) myofibrillar proteins

Mussel myofibrillar proteins (MMP) suspensions (10.6% ± 0.5%, w/v) were treated by high-pressure homogenization (HPH) at 0 (control), 20, 40, 60, 80 or 100 MPa for 3 cycles. Particle size distribution, zeta potential, solubility, water and oil holding capacity, emulsifying, foaming properties, secondary structure, free sulfhydryl and surface hydrophobicity of the obtained suspensions were analyzed. The results showed that functional properties of MMP significantly (P < 0.05) improved after HPH treatment. Absolute zeta potential, emulsifying activity index, emulsion stability index, foaming ability and foaming stability increased by 23.64 mV, 14.99 m2/g, 4.3 min, 17.3% and 29.7% at 80 MPa, protein solubility and oil holding capacity increased by 7.4% and 1300% at 100 MPa. However, HPH treatment significantly (P < 0.05) decreased particle size and water holding capacity. HPH treatment altered secondary structure, tertiary and quaternary structure. Functionality improvements mainly resulted from changes in structure and decrease in particle size. The results showed that HPH has potential for improving functional properties of MMP, thus expand its application in food industry.

High-Pressure Homogenization Alters Physicochemical Properties and In Vitro Digestibility of Chinese Yam (Dioscorea Opposita Thunb.) Starch

In this study, Chinese yam starch-water suspension (8%) were subjected to high-pressure homogenization (HPH) at 100 MPa for increasing cycle numbers, and its effect of on the physicochemical properties of the starch was investigated. Results of the polarizing microscope observations showed that the starch granules were disrupted (i.e. greater breakdown value) after HPH treatment, followed by a decrease in cross polarization. After three HPH cycles, the crystallinity of starch decreased, while the crystal type remained unaltered. Meanwhile, the contents of rapidly digestible starch and slowly digestible starch were increased. On the contrary, resistant starch content was decreased. Our results indicate that HPH treatment resulted in reduction of starch crystallinity and increase of starch digestibility.

High pressure homogenization of mechanically deboned chicken meat protein suspensions to improve mechanical and barrier properties of edible films

The effect of high pressure homogenization (HPH) on edible films obtained from mechanically deboned chicken meat proteins (MDCM-P), a by-product of poultry industry, was investigated. Film forming suspensions (FFS) were prepared at 4% protein concentration and homogenized up to 150 MPa. FFSs were characterized in terms of particle size and steady shear rheology, whereas optical, barrier, mechanical and microstructural properties of resulting films were determined. Particle size of suspensions decreased as homogenization pressure increased, and suspensions treated up to 50 MPa showed shear thinning behavior with higher yield stress, while higher HPH treatment caused Newtonian flow. Shear stress-shear rate data were fitted to Herschel-Bulkley model. HPH treatment improved film appearance, and all films displayed good barrier properties against UV light which induces lipid oxidations in foods. The decreasing particle size of HPH treated MDCM-P suspensions up to 100 MPa caused lower water vapour permeability (WVP) and higher tensile strength (TS), and these results were also confirmed by film micrographs which had homogeneous, non-porous and un-cracked surface images. However, porous cross sectional images were observed from 150 MPa HPH treated films. FTIR spectra of films showed similar backbone structure, and the secondary structure of films was analyzed from the area of the deconvoluted Amide I peak, which changed significantly. β-sheet and β-turn contents of films showed high correlation coefficients with TS and EAB values. It can be concluded from this study that HPH applications up to 100 MPa can enhance the mechanical and barrier properties of films.

Effects of High-Pressure Homogenization at Different Pressures on Structure and Functional Properties of Oyster Protein Isolates

Abstract Oyster protein isolate (OPI) suspensions (6.19 % ± 0.82 %, w/v) were treated by high-pressure homogenization (HPH) at 0 (control), 20, 40, 60, 80 or 100 MPa for three cycles. Protein profiles, secondary structure, free sulfhydryl, surface hydrophobicity, particle size distribution, zeta-potential, solubility, water and oil holding capacity (OHC), emulsifying and foaming properties of the obtained suspensions were analyzed. The results showed that HPH treatment did not cause changes in protein profiles of OPI, but caused changes in secondary structure, content of α-helix decreased but content of β-turn and random coil increased significantly (P &lt; 0.05). Free sulfhydryl and surface hydrophobicity all increased significantly (P &lt; 0.05) after HPH treatment, indicating that tertiary and quaternary structures changed. Functional properties of OPI significantly (P &lt; 0.05) improved after HPH treatment, such as zeta-potential (from −12.67 to −33.57 mV), solubility (from 20.24 % to 57.99 %), OHC (from 981.77 % to 1229.40 %), foaming ability (from 17.50 % to 35.00 %), foaming stability (from 44.49 % to 66.60 %), emulsifying activity index (from 8.87 to 17.06 m2/g) and emulsion stability index (from 14.65 to 41.68 min). At 60 MPa and 80 MPa, the improvements were more remarkable. However, HPH treatment significantly (P &lt; 0.05) decreased particle size (from 200–500 nm to 0–200 nm) and water holding capacity (from 341.15 % to 216.96 %). These improvements were closely related to structural changes and reduction of particle size. Application of different pressures affected functional properties of OPI. These results could provide information for determining HPH applying condition in OPI modification.

Effect of high pressure homogenization (HPH) on functional and rheological properties of hazelnut meal proteins obtained from hazelnut oil industry by-products

The effect of high pressure homogenization (HPH) on functional and rheological properties of hazelnut meal proteins was investigated. Hazelnut meal proteins were extracted from hazelnut oil industry by-products. Protein patterns remained unchanged up to 75 MPa, and band intensity decreased when pressure reached 100 MPa. HPH treatment decreased particle size, produced higher zeta potential and hence, improved water solubility, which resulted in higher emulsifying and foaming properties. Hazelnut meal protein suspensions displayed shear thinning behavior and higher G′ than Gʹ' which means suspensions had soft-gel network. For better understanding of internal structure, elastic and viscous behavior, creep and recovery tests were explained by Burgers and exponential decay models. Final percentage recovery increased after 100 MPa due to strengthened solid-like structure of protein suspensions. As a result, functional and rheological properties of proteins can be successfully improved by HPH treatment, and thus hazelnut oil industry by-products have added value once processed by HPH.

Effects of Limited Hydrolysis and High-Pressure Homogenization on Functional Properties of Oyster Protein Isolates

In this study, the effects of limited hydrolysis and/or high-pressure homogenization (HPH) treatment in acid conditions on the functional properties of oyster protein isolates (OPI) were studied. Protein solubility, surface hydrophobicity, particle size distribution, zeta potential, foaming, and emulsifying properties were evaluated. The results showed that acid treatment led to the dissociation and unfolding of OPI. Subsequent treatment such as limited proteolysis, HPH, and their combination remarkably improved the functional properties of OPI. Acid treatment produced flexible aggregates, as well as reduced particle size and solubility. On the contrary, limited hydrolysis increased the solubility of OPI. Furthermore, HPH enhanced the effectiveness of the above treatments. The emulsifying and foaming properties of acid- or hydrolysis-treated OPI significantly improved. In conclusion, a combination of acid treatment, limited proteolysis, and HPH improved the functional properties of OPI. The improvements in the functional properties of OPI could potentiate the use of oyster protein and its hydrolysates in the food industry.

Combined high-power ultrasound and high-pressure homogenization nanoemulsification: The effect of energy density, oil content and emulsifier type and content

Combinations of ultrasound (US) and high-pressure homogenization (HPH) at low-medium energy densities were studied as alternative processes to individual US and HPH to produce Tween 80 and whey protein stabilized nanoemulsions, while reducing the energy input. To this aim, preliminary trials were performed to compare emulsification efficacy of single and combined HPH and US treatments delivering low-medium energy densities. Results highlighted the efficacy of US-HPH combined process in reducing the energy required to produce nanoemulsions stabilized with both Tween 80 and whey protein isolate. Subsequently, the effect of emulsifier content (1–3% w/w), oil amount (10–20% w/w) and energy density (47–175 MJ/m3) on emulsion mean particle diameter was evaluated by means of a central composite design. Particles of 140–190 nm were obtained by delivering 175 MJ/m3 energy density at emulsions containing 3% (w/w) Tween 80 and 10% (w/w) oil. In the case of whey protein isolate stabilized emulsions, a reduced emulsifier amount (1% w/w) and intermediate energy density (120 MJ/m3) allowed a minimum droplet size around 220–250 nm to be achieved. Results showed that, in both cases, at least 50% of the energy density should be delivered by HPH to obtain the minimum particle diameter.

Influence of High Pressure Homogenization on Free Fatty Acid Formation in Nannochloropsis sp.

Although Nannochloropsis lipids have many potential applications in biofuels and high value products, their extraction is limited by the tough cell wall of this species. High pressure homogenization (HPH) can be used to improve the extraction efficiency. However, this can possibly induce free fatty acid (FFA) formation, which has a negative impact on oil quality. In this study, the HPH pressure and number of passes are varied in a full factorial design to study the impact of these factors on FFA formation, lipid extraction efficiency, and fatty acid profile. It is found that substantial amounts of FFA are formed during HPH treatments when compared to the non‐disrupted biomass. The FFA formation is mostly influenced by the number of passes applied, which can explained by a combined effect of the longer time residing as a wet paste and the temperature increase during the treatment. The large amount of FFA formed during the least intensive HPH treatment is in contrast with only a slight increase of the lipid extraction efficiency, which indicates that minor damage to the cell is sufficient to induce lipolytic reactions. The relative fatty acid profile after HI extraction is not influenced by the HPH treatment.Practical Applications: These results have important implications for the application of HPH treatments on microalgae with the aim to improve the extraction efficiency. It is demonstrated that more intensive HPH treatments with several passes are necessary to improve the extraction efficiency of Nannochloropsis lipids. However, the least intensive HPH treatments (1 pass at 400 bar) already induced the formation of substantial amounts of FFA. Consequently, to produce a biomass with a low FFA content and a high lipid extraction efficiency, a compromise should thus be made.High pressure homogenization (HPH) can efficiently be used to improve the extraction effiency of interesting compounds from Nannochloropsis cells. However, this treatment also induces the formation of free fatty acids (FFA), which have a negative influence on oil quality.

Effect of pulsed electric fields and high pressure homogenization on the aqueous extraction of intracellular compounds from the microalgae Chlorella vulgaris

Pulsed Electric Fields (PEF) and High Pressure Homogenization (HPH) are promising and scalable cell disruption technologies of microalgae cells. In this work, the permeabilization degree, morphological properties, and extractability of intracellular compounds from microalgae Chlorella vulgaris suspensions (1.2%, w/w) were investigated as a function of PEF treatment at different electric field strengths (10–30 kV/cm) and total specific energy input (20–100 kJ/kg), in comparison with the more disruptive HPH treatment (150 MPa) at different number of passes (nP = 1–10). The conductivity and the particle size analyses, as well as the SEM images, clearly showed that PEF induces the permeabilization of the cell membranes in an intensity-dependent manner, without producing any cell debris, whereas HPH treatment causes the total disruption of the algae cells into small fragments. Coherently with the lower permeabilization capability, PEF promoted the selective extraction of carbohydrates (36%, w/w, of total carbohydrates), and low molecular weight proteins (5.2%, w/w, of total proteins). On the other hand, HPH induced the undifferentiated release of all the intracellular content, resulting in a 1.1 and 10.3 fold higher yields than PEF, respectively of carbohydrates and protein.These results suggest that, in a multi-stage biorefinery, PEF could represent a suitable cell disruption method for the selective recovery of small-sized cytoplasmic compounds, while HPH should be placed at the end the cascade of operations allowing the recovery of high molecular weight intracellular components.

Recovery of Fuel-Precursor Lipids from Oleaginous Yeast

Bioderived lipids offer a potentially promising intermediate to displace petroleum-derived diesel. One of the key challenges for the production of lipids via microbial cell mass is that these products are stored intracellularly and must be extracted and recovered efficiently and economically. Thus, improved methods of cell lysis and lipid extraction are needed. In this study, we examine lipid extraction from wet oleaginous yeast in combination with seven different cell lysis approaches encompassing both physical and chemical techniques (high-pressure homogenization, microwave and conventional thermal treatments, bead beating, acid, base, and enzymatic treatments) to facilitate lipid extraction from a model oleaginous yeast strain, Lipomyces starkeyi. Of the seven techniques investigated, acid treatment led to the highest lipid recovery yields. Further exploration of acid treatment and integration with an economic model revealed that treatment at 170 °C for 60 min at 1 wt % H2SO4 and 8 wt % yeast solids re...