Effect of high-pressure treatment on trypsin hydrolysis and antioxidant activity of egg white proteins

Effects of Sequential Combination of Moderate Pressure and Ultrasound on Subsequent Thermal Pasteurization of Liquid Whole Egg

As an alternative to commercial whole egg thermal pasteurization (TP), the sequential combination of moderate pressure (MP) and/or ultrasound (US) pre-treatments prior to a shorter TP was evaluated. The use of US alone or in combination with MP or TP resulted in an inactivation that was far from that of commercial TP. Nevertheless, when these three technologies were combined (MP-US-TP, 160 MPa/5 min-50% amplitude/1 min-60 °C/1.75 min), a safety level comparable to that of commercial TP was established. This was likely due to a decrease in the thermal resistance of Salmonella Senftenberg 775/W caused by MP and US pre-treatments. Regarding liquid whole egg (LWE) properties, using raw LWE as a reference, TP and MP treatments each decreased protein solubility (7-12%), which was accompanied by a viscosity increment (41-59%), whereas the US-only and MP-US-TP treatments improved protein solubility (about 4%) and reduced viscosity (about 34%). On average, all treatments lowered the emulsifying properties of LWE by 35-63%, with the MP-US-TP treatment having a more dramatic impact than commercial TP. In addition, the US-only, MP-only, and MP-US-TP treatments had the greatest impact on the volatile profile of LWE, lowering the concentration of the total volatile components. In comparison to commercial TP, LWE treated with MP-US-TP exhibited greater protein solubility (19%), lower viscosity (56%), and comparable emulsifying stability, but with a decreased emulsifying capacity (39%) and a lower total volatile compounds content (77%). Considering that a combined treatment (MP-US-TP) is lethally equivalent to commercial TP, but the latter better retained the quality properties of raw LWE, including volatiles, the application of MP followed by US pre-treatments before a shorter TP did not demonstrate significant advantages on quality parameters in comparison to commercial TP.

Potential Application of High Hydrostatic Pressure on the Production of Hydrolyzed Proteins with Antioxidant and Antihypertensive Properties and Low Allergenicity: A Review

The high hydrostatic pressure (HHP) process has been studied for several applications in food technology and has been commercially implemented in several countries, mainly for non-thermal pasteurization and shelf-life extension of food products. HHP processing has been demonstrated to accelerate proteolytic hydrolysis at a specific combination of pressure and pressure-holding time for a given protein source and enzyme. The enzymatic hydrolysis of proteins is a well-known alternative to producing biologically active peptides, with antioxidant and antihypertensive capacity, from different food protein sources. However, some of these protein sources contain allergenic epitopes which are often not degraded by traditional hydrolysis. Moreover, the peptide profile and related biological activity of a hydrolysate depend on the protein source, the enzymes used, the parameters of the proteolysis process (pH, temperature, time of hydrolysis), and the use of other technologies such as HHP. The present review aims to provide an update on the use of HHP for improving enzymatic hydrolysis, with a particular focus on studies which evaluated hydrolysate antihypertensive and antioxidant capacity, as well as residual allergenicity. Overall, HHP has been shown to improve the biological properties of hydrolysates. While protein allergenicity can be reduced with traditional hydrolysis, HHP can further reduce the allergenicity. Compared with traditional hydrolysis methods, HHP-assisted protein hydrolysis offers a greater opportunity to add value to protein-rich products through conversion into high-end hydrolysate products with enhanced nutritional and functional properties.

Application of preliminary high-pressure processing for improving bioactive characteristics and reducing antigenicity of whey protein hydrolysates

This study investigated the use of Novo Pro-D® (NPD) and Ficin (FC) as alternative proteases for the production of bioactive peptides with reduced allergenicity from whey protein concentrate (WPC). In addition, the use of high hydrostatic pressure processing as pre-treatment of WPC and its impact on the final characteristics of hydrolysates were also evaluated. NPD treatments generated hydrolysates with a 98% reduction of soluble proteins, greater in vitro antioxidant capacity, and less immunoreactivity when compared to FC ones. However, pre-treatment was an essential tool to improve WPC hydrolysis when FC was used, resulting in hydrolysates with less soluble proteins, enhanced antioxidant capacity, and less allergenicity compared with conventional hydrolysis. As for NPD, the pre-treatment of WPC improved the in vitro antioxidant capacity and resulted in a 100% reduction in immunoreactivity to β-lactoglobulin in a shorter processing time. Importantly, bioactive peptides generated by FC displayed an improved ability to induce in vitro arterial relaxation, compared with those obtained from NPD process. Therefore, this study provides innovative evidence regarding how the proteases used for production of whey hydrolysates can improve its biological effects, and discloses the use of high hydrostatic pressure combined with enzymatic hydrolysis as a promising alternative to produce hydrolysates with improved properties.

Chicken Egg Proteins and Derived Peptides with Antioxidant Properties

In addition to their high nutritional value, some chicken egg proteins and derivatives such as protein hydrolysates, peptides and amino acids show antioxidant properties which make them prominent candidates for the development of functional foods, drawing attention to both the food and biopharmaceutical industries. This review summarizes current knowledge on antioxidant activity of chicken egg proteins and their derived peptides. Some egg proteins such as ovalbumin, ovotransferrin and lysozyme from egg white or phosvitin from yolk have shown antioxidant properties, although derived peptides have higher bioactive potential. The main process for obtaining egg bioactive peptides is enzymatic hydrolysis of its proteins using enzymes and/or processing technologies such as heating, sonication or high-intensity-pulsed electric field. Different in vitro assays such as determination of reducing power, DPPH and ABTS radical-scavenging activity tests or oxygen radical absorbance capacity assay have been used to evaluate the diverse antioxidant mechanisms of proteins and peptides. Similarly, different cell lines and animal models including zebrafish, mice and rats have also been used. In summary, this review collects all the knowledge described so far regarding egg proteins and derived peptides with antioxidant functions.

A comparative study on properties of fish meat hydrolysates produced by an enzymatic process at high pressure

Fish meat hydrolysates (FMHs) were produced from nine fishes at a high pressure of 300 MPa using Flavourzyme 500MG and a protease mixture including Flavourzyme 500MG, Alcalase 2.4L, Protamex, and Marugoto E. The electropherograms of the FMHs showed major far-migrating peptide bands in the vicinity of 5 kDa. The total soluble solids (TSS) and soluble nitrogen content in the FMHs were species-specific and were mostly higher in the case of four-enzyme hydrolysis. Most of the HPLC peptide peaks of the rockfish meat hydrolysates appeared within 10 min of elution, and total free amino acids in the hydrolysate increased abruptly as a result of four-enzyme hydrolysis. The FMHs, which were high in TSS and soluble nitrogen, may be applicable for use in food as seasoning, and could be produced efficiently via the enzymatic process used in this study.

Modifying the Functional Properties of Egg Proteins Using Novel Processing Techniques: A Review

Egg proteins can be used in a wide range of food products, owing to their excellent foaming, emulsifying, and gelling properties. Another important functional property is the susceptibility of egg proteins to enzymatic hydrolysis, as protein digestion is closely related to its nutritional value. These functional properties of egg proteins are likely to be changed during food processing. Conventional thermal processing can easily induce protein denaturation and aggregation and consequently reduce the functionality of egg proteins due to the presence of heat-labile proteins. Accordingly, there is interest from the food industry in seeking novel nonthermal or low-thermal techniques that sustain protein functionality. To understand how novel processing techniques, including high hydrostatic pressure, pulsed electric fields, ionizing radiation, ultraviolet light, pulsed light, ultrasound, ozone, and high pressure homogenization, affect protein functionality, this review introduces the mechanisms involved in protein structure modification and describes the structure-functionality relationships. Novel techniques differ in their mechanisms of protein structure modification and some have been shown to improve protein functionality for particular treatment conditions and product forms. Although there is considerable industrial potential for the use of novel techniques, further studies are required to make them a practical reality, as the processing of egg proteins often involves other influencing factors, such as different pH and the presence of other food additives (for example, salts, sugar, and polysaccharides).

Can acceptable quality angel food cakes be made using pasteurized shell eggs? The effects of mixing factors on functional properties of angel food cakes

Due to recent Salmonella outbreaks, the pasteurized shell egg market is rapidly growing. One objection to using pasteurized eggs is the belief that they will produce unacceptable angel food cakes. Eggs were pasteurized using a hot water immersion process (56.7°C for 60 min) similar to that used by industry. Angel food cakes were made from the pasteurized egg white (PEW) as well as from raw egg white (REW) for comparison. Meringues were made using three mixer speed settings (low, medium, and high) and three durations for each speed. Functional qualities such as egg foaming were evaluated. Angel food cakes were compared in terms of cake volume, texture profile, and color values. When the optimal processing factors used for REW were applied to PEW, an inferior meringue was formed. However, by increasing the mixing time for PEW by 200% at the highest speed, an acceptable meringue was formed. The best angel food cake prepared from PEW had a volume only 6.8% less than that of the best cake prepared from REW. Texture profile analyses showed that the best angel food cake made from PEW was 13% firmer, 7.4% less springy, and 62% chewier than that from REW. Color analyses showed that PEW made a slightly darker colored cake crust than REW, although there were no significant differences in the crumb color. Modifying the mixing conditions for PEW resulted in angel food cakes with quality similar to that of cakes made with REW, thus overcoming an objection to using safer pasteurized shell eggs.

Effect of Soluble Solids and High Pressure Treatment on Rheological Properties of Protein Enriched Mango Puree

The effects of high pressure treatment on the rheological properties of protein enriched mango puree were evaluated. In the first part, the original soluble solids in mango puree (28° Brix) was lowered to 26, 23 and 20° Brix, and each was supplemented with 2, 5 and 8% of whey protein to assess the influence of added protein. The samples were then evaluated by dynamic rheology. Pressure treatment resulted in a progressive increase in elastic (G') and viscous modulii (G″) as well as complex viscosity (η*). Values of G' were higher than G″ demonstrating that the product behaved more like a gel. Additional tests were carried out by simultaneously varying protein and soluble solids contents, and keeping the total solids at 28%. In this case, the effects of pressure levels and holding times were similar to previous results. However, the positive effects of higher protein were negated by the negative effects of lower soluble solids, resulting in an overall decreasing effect on rheology. The developed models effectively predicted the combined influence of protein and soluble solid concentrations on rheological parameters (R2 > 0.85). Sensory evaluation of 2% and 5% protein supplemented and pressure treated (500 MPa/3 min) mango puree yielded acceptable sensory qualities, resulting in a product with enriched protein content.

Pulsed electric fields treatment at different pH enhances the antioxidant and anti-inflammatory activity of ovomucin-depleted egg white

This research investigated the effects of pulsed electric fields (PEF) (1.4-1.7 kV/cm, 653-695 kJ/kg) and heating (60 and 80 °C for 10 min) at different pH (4, 5, 7, and 9) on the antioxidant and anti-inflammatory activity of ovomucin-depleted egg white (OdEW) after in vitro gastrointestinal hydrolysis. PEF and heating (80 °C for 10 min) at pH 4 enhanced the antioxidant activity of the whole hydrolysates, chemically determined using DPPH and ORAC assays. Furthermore, the anti-inflammatory activity of protein hydrolysates was assessed in lipopolysaccharide-stimulated HT-29 cells using ELISA assay. PEF and heating at pH 4 enhanced the anti-inflammatory activity of the whole hydrolysates dose-dependently. Hydrolysates at 1 mg/ml showed similar inhibition (35.5% and 35.9%) of interleukin-8 production, due to PEF treatment and heating (80 °C for 10 min), respectively. Results indicated that prior PEF treatment can analogously enhance both antioxidant and anti-inflammatory activity of OdEW hydrolysates to heating, with potentially reduced thermal input.

Bioactive peptides derived from egg proteins: A review

Egg proteins have various functional and biological activities which make them potential precursor proteins for bioactive peptide production. Simulated in vitro gastrointestinal digestion and enzymatic hydrolysis using non-gastrointestinal proteases have been used as tools to produce these peptides. Bioactive peptides derived from egg proteins are reported to display various biological activities, including angiotensin I-converting enzyme (ACE) inhibitory (antihypertensive), antioxidant, antimicrobial, anti-inflammatory, antidiabetic and iron-/calcium-binding activities. More importantly, simulated in vitro gastrointestinal digestion has indicated that consumption of egg proteins has physiological benefits due to the release of such multifunctional peptides. This review encompasses studies reported to date on the bioactive peptide production from egg proteins.

Enzymatic hydrolysis of anchovy fine powder at high and ambient pressure, and characterization of the hydrolyzates

BACKGROUND

At specific conditions of high pressure, the stability and activity of some enzymes are reportedly known to increase. The aim of this study was to apply pressure-tolerant proteases to hydrolyzing anchovy fine powder (AFP) and to determine product characteristics of the resultant hydrolyzates.

RESULTS

Anchovy fine powder enzyme hydrolyzates (AFPEHs) were produced at 300 MPa and ambient pressure using combinations of Flavourzyme 500MG, Alcalase 2.4L, Marugoto E and Protamex. When the same protease combination was used for hydrolysis, the contents of total soluble solids, total water-soluble nitrogen and trichloroacetic acid-soluble nitrogen in the AFPEHs produced at 300 MPa were conspicuously higher than those in the AFPEHs produced at ambient pressure. This result and electrophoretic characteristics indicated that the high-pressure process of this study accelerates protein hydrolysis compared with the ambient-pressure counterpart. Most peptides in the hydrolyzates obtained at 300 MPa had molecular masses less than 5 kDa. Functionality, sensory characteristics and the content of total free amino acids of selected hydrolyzates were also determined.

CONCLUSION

The high-pressure hydrolytic process utilizing pressure-tolerant proteases was found to be an efficient method for producing protein hydrolyzates with good product characteristics.

Enzymatic protein hydrolysates from high pressure-pretreated isolated pea proteins have better antioxidant properties than similar hydrolysates produced from heat pretreatment

Isolated pea protein (IPP) dispersions (1%, w/v) were pretreated with high pressure (HP) of 200, 400, or 600 MPa for 5 min at 24 °C or high temperature (HT) for 30 min at 100 °C prior to hydrolysis with 1% (w/w) Alcalase. HP pretreatment of IPP at 400 and 600 MPa levels led to significantly (P<0.05) improved (>40%) oxygen radical absorption capacity (ORAC) of hydrolysates. 2,2-Diphenyl-1-picrylhydrazyl, superoxide radical and hydroxyl radical scavenging activities of pea protein hydrolysates were also significantly (P<0.05) improved (25%, 20%, and 40%, respectively) by HP pretreatment of IPP. Protein hydrolysates from HT IPP showed no ORAC, superoxide or hydroxyl scavenging activity but had significantly (P<0.05) improved (80%) ferric reducing antioxidant power. The protein hydrolysates had weaker antioxidant properties than glutathione but overall, the HP pretreatment was superior to HT pretreatment in facilitating enzymatic release of antioxidant peptides from IPP.