Impact of High Hydrostatic Pressure on the Quality and Functional Properties of Rehydrated Animal Blood Plasma

Abstract

In this present study, bovine blood plasma suspensions (12 w/v%) were HHP-treated at 300, 400, 450, 500, 550 and 600 MPa for 5 min. The effect of HHP treatment on the color, rheological properties and digestibility of the samples was investigated. The changes in proteins due to HHP treatment were monitored using SDS-PAGE. Furthermore, the HHP-treated samples were subjected to a 44-day storage experiment and the development of mesophilic aerobic bacterial counts was investigated. Even the application of 300 MPa of pressure induced a significant change in the color of the samples. With the application of a pressure of 300–550 MPa, dilatational rheological behavior was observed, while at 600 MPa, the sample was characterized by pseudoplastic flow properties. The SDS-PAGE study found that there was no significant effect of HHP treatment on the protein fractions in plasma. The application of 450 MPa of pressure improved the digestibility of the plasma suspension. Blood plasma produced in this way has better nutritional value in accordance with consumer needs. The study of mesophilic aerobic bacteria count found that HHP treatments at 550 and 600 MPa improved the shelf life of the samples by 30 days. Additionally, the observed microbial stability improvements suggest that HHP-treated blood plasma could be a viable alternative for extending shelf life in processed food applications, reducing the need for synthetic preservatives. These results suggest that HHP treatment can enhance the functional properties of blood plasma suspensions, enabling their use in food formulations such as protein supplements, emulsifiers and texturizing agents. This approach aligns with the industry’s need for sustainable protein sources and clean-label ingredients.

1. Introduction

Population growth over the last century has led to a significant increase in food demand. The United Nations projects the world population to reach 9.7 billion by 2050, 10.8 billion by 2080 and 11.2 billion by 2100 [1]. Some estimates suggest that food production efficiency will need to increase by 50–70% by 2050 to feed an additional two billion people [2]. Accordingly, sustainable development has become a key consideration for the food industry and encourages the exploration of processing techniques that can improve the nutritional and functional properties of food while minimizing environmental impact [3]. Thus, processing by-products such as blood not only solves the issue of waste management but also provides significant benefits in terms of environmental sustainability and nutritional value, which can contribute to the circular economy [4].

Blood is considered one of the main by-products of the meat industry due to the large amount produced daily [5]. Blood has an outstanding nutritional value due to its high protein content and amino acid profile. For this reason, it is also called “liquid protein” or “liquid meat” [6]. Blood constitutes approximately 2.4–8% of the animal’s live weight or 6–7% of the lean meat content of a slaughtered animal [7]. This red-colored liquid connective tissue can be considered a complex fluid composed of water, cells, enzymes, proteins and other organic and inorganic substances, which can be divided into two fractions, the cellular fraction and the plasma [8]. Animal blood plasma (serum) is considered the most complex colloidal system of all known natural fluids. Since plasma contains complexes of many different biologically active compounds, it is reasonable to consider blood a “super complex colloidal system”. Plasma is the liquid part of blood that does not contain blood cells [9]. Mammalian plasma usually contains 6–8% w/v protein, mainly albumin (56–60%); globulins -α₁-, α₂-, β- and γ-globulins (36–40%) and fibrinogen (0.6–4%) [10].

Blood is currently underutilized, and its main applications are focused on animal feed, composting or biogas production, which represent low added value [11]. In food applications, blood plasma plays an important role in the meat industry, as it forms a gel when heated and has better binding properties than many other binders (e.g., gelatin, meat powders and wheat gluten), although it is weaker than egg white. It also has excellent emulsifying properties, which help to bind meat proteins, fats and water in products such as sausages and pâtés. The food industry also uses it as a protein supplement and fat substitute, as well as an egg substitute in bakery products, thereby reducing production costs. Blood plasma can also be used to increase the protein content of pasta products, which could be a cost-effective solution for manufacturers [8,12]. The processing of blood for human consumption or higher added value uses (e.g., biomaterials, bioactive compounds) still represents a small part of total blood consumption. A total of 30–40% of total food production is lost as waste and/or by-products before reaching the market [5]. Rapid advances in science and technology may transform blood collected from slaughterhouses into a useful alternative source for human consumption, as blood has unique nutritional and functional properties. This practice is an excellent effort to minimize environmental impacts and encourage innovation to improve resource sustainability [13,14]. The meat industry is faced with the challenge of making better use of all slaughter products, including blood. Finding new applications for blood components is an important challenge for scientists and there is a need to develop processes and applications that allow for the larger-scale utilization of animal blood, both to eliminate the significant risk of contamination and to prevent the loss of this potentially valuable material [14,15].

In recent years, there has been a significant shift in consumer trends, with a growing demand for natural, additive-free and fresh products. Following these current trends, new natural products, minimally processed and free of artificial ingredients, have led to the emergence of emerging processing techniques [16]. One such food processing technology is high hydrostatic pressure (HHP) treatment. HHP is a non-thermal processing method that is used as an alternative to traditional thermal processes to improve food safety due to its ability to inactivate harmful microorganisms while preserving the quality, nutrients and organoleptic properties of food [17].

Untreated rehydrated plasma suspension supports microbial growth, leading to spoilage, safety issues and deterioration of functional properties such as emulsification and gelation. Poor storage stability limits shelf life and commercial use. HHP treatment enhances microbiological stability by inactivating pathogens without heat, preserving protein functions and extending shelf life for safe food applications.

The food industry often uses the process of dissolving food powders in water and adding the resulting suspension to food. This allows for the easy incorporation of nutrients, additives or functional ingredients into products. This method ensures uniform distribution and accurate dosing and can improve the consistency and quality of products; for example, when fortifying yogurts, drinks, bakery products, ice cream and frozen desserts. The study of HHP-treated plasma suspensions will help to optimize solubility, stability and bioavailability, improving their functionality and suitability for food fortification. This knowledge will support improved formulation strategies, improving nutrition, safety and sensory quality in the food industry.

Several studies have already reported on the various applications of blood plasma in the food industry [18,19,20]; however, to our knowledge, there are no reports available regarding the testing of HHP-treated rehydrated blood plasma. Therefore, in this present study, we aimed to investigate what changes HHP treatment causes in the color, rheological properties and protein structure of blood plasma suspensions, as well as what effect it has on the digestibility of blood plasma. Furthermore, we investigated the effect of HHP treatment on the development of mesophilic aerobic bacterial counts in bovine blood plasma suspensions on day 0 and during the 44-day storage experiment.

2. Materials and Methods

2.1. Preparation of Sample and HHP Treatment

Bovine blood plasma powder 70 B (Sonac Burgum, Loenen, The Netherlands) was used for the study. In total, 3 × 350 mL of 12 w/v% suspensions were prepared from the blood plasma samples intended for HHP treatment. The samples were then packaged in 200 mL PA–PE (polyamide–polyethylene) bags (90 µm: 20 µm PA + 70 µm PE; AMCO Kft, Budapest, Hungary), which were sealed with a foil sealer, ensuring that as little air as possible remained in the packaging. The flexible PA–PE material allows for uniform pressure transmission while preventing oxygen ingress, which helps maintain product integrity and extend shelf life. For samples for microbiological examinations, 20 mL samples were placed in the packing bags. The samples were stored in a refrigerator at 4 ± 1 °C until use. The samples were pressure treated using a Hiperbaric 135 (Hiperbaric, Burgos, Spain) pressure treatment system. All samples were subjected to a 5 min pressure treatment. The pressure values used were as follows: 0 MPa (control), 300 MPa, 400 MPa, 450 MPa, 500 MPa, 550 MPa and 600 MPa. The application of HHP in the pressure range of 300–600 MPa provides an optimal balance between microbial inactivation and food quality preservation. Therefore, the food industry prefers to use it for products such as fruit juices, meats and ready meals. This is proven by the fact that most of the HHP-treated products on the food market are treated at pressures between 300 and 600 MPa for less than 5 min [21].

2.2. Color Measurement

A Konica Minolta CR-400 (Konica Minolta Sensing Inc., Osaka, Japan) colorimeter was used to perform the color measurements. The instrument was calibrated with a white tile before each measurement and the color of the samples was measured by pouring them into a Petri dish. Three parallel measurements were performed for each sample. During the measurements, the values of lightness (L*), redness (a*) and yellowness (b*) were recorded. The color difference (ΔE) was calculated using the following formula [22]: ${\mathrm{E}}_{\mathrm{a}\mathrm{b}}^{\mathrm{*}}=\sqrt{{\left(\mathsf{\Delta }{\mathrm{L}}^{\mathrm{*}}\right)}^2+{\left(\mathsf{\Delta }{\mathrm{a}}^{\mathrm{*}}\right)}^2+{\left(\mathsf{\Delta }{\mathrm{b}}^{\mathrm{*}}\right)}^2}$.

2.3. Examination of Rheological Properties

The rheological behavior of HHP-treated blood plasma suspensions was investigated using an MCR 92 rheometer (Anton Paar Ltd., Les Ulis, France) in rotational mode. The properties of the samples under varying shear stress were determined using a concentric cylinder (CC27-SN16145) measuring system with the following parameters: cup diameter 28.920 mm, bob diameter 26.651 mm, bob length 40.003 mm, active length 120.2 mm and positioning length 72.5 mm. Anton Paar RheoCompass software (version 1.21.852) was used to control the instrument and thus record the curves. Measurements were performed in triplicate for each sample at 20 °C. The shear stress analysis was performed at decreasing shear rates between 1000 and 1 s⁻¹, where 31 data points were recorded. The Herschel–Bulkley model (Equation (1)) was used to describe the rheological properties of the samples [23,24]. All R² values of the fitted model were higher than 0.95.

$$\mathsf{\tau }={\mathsf{\tau }}_0+\mathrm{K}{\mathsf{\gamma }}^{\mathrm{n}}$$

(1)

where τ—shear stress (Pa); τ₀—yield stress (Pa); γ—shear rate (s⁻¹); K—consistency coefficient (Pa sⁿ); n—flow behavior index (dimensionless).

2.4. Sodium Dodecyl-Sulfate Polyacrylamide Gel Electrophoresis (SDS-PAGE)

The protein analysis of HHP-treated blood plasma suspensions was performed using SDS-PAGE [25]. Hand-cast gels 6–15% (w/v) (acrylamide/bis-acrylamide, 83 mm × 73 mm × 1.0 mm) were used for electrophoresis and a vertical system was applied using SDS-PAGE during the measurement (Bio-Rad mini-Protean Tetra System, Bio-Rad, Hercules, CA, USA). Five µL of each sample was added to 150 µL of 2 × Laemmli sample buffer (Bio-Rad, Hercules, CA, USA). The sample and sample buffer mixture were heated in a temperature-controlled water bath for 2 min at 100 °C. From the dilutions, 7 μL molecular standard and 4 μL of protein solutions were loaded into the wells and run for 45 min at 200 V. The gels were stained for 30 min with 0.2% Coomassie brilliant blue (R-250, Bio-Rad, Hercules, CA, USA). The range of molecular standard (Precision Plus Protein All Blue Standards, Bio-Rad, Hercules, CA, USA) was 250–10 kDa. The stained gel images were captured using a Gel Doc XR+ System (Bio-Rad, Hercules, CA, USA). The identification and the densities of the bands were quantified using Quantity One (version 4.6.8) and Image Lab 6.1 software programs (Bio-Rad, Hercules, CA, USA).

2.5. In Vitro Digestion

The in vitro digestion experiment was performed according to the method developed by Minekus et al. [26]. Simulated digestive fluids were used during digestion, which were: saliva (SSF, Simulated Salivary Fluid), gastric fluid (SGF, Simulated Gastric Fluid) and small intestinal fluid (SIF, Simulated Intestinal Fluid). The digestive juices contained the appropriate amounts and proportions of electrolyte solution, digestive enzymes, calcium chloride and water found in this section of the alimentary canal. Since the focus of the samples used in the measurement was on protein breakdown, and therefore carbohydrate breakdown in the mouth was not of major importance, the SSF did not contain amylase enzyme. The initial weight of the samples to be digested was 1 g, and the ratio of food to artificial saliva was 50:50 w/v. In accordance with the harmonized digestion protocol, the activity of the enzymes was adjusted to the assumed physiological conditions. The activity of the pepsin (Sigma-Aldrich, St. Louis, MO, USA, P7012) and pancreatin (Sigma-Aldrich, St. Louis, MO, USA, P7545) used was determined according to the method of Anson [27] and Hummel [28]. For pepsin, it was 1124.7 U/mg, and for pancreatin, it was 5.08 U/mg. The bile acid concentration was 2.05 mM/mg as determined by a Bile Acids Enzymatic Cycling Kit (Dialab Ltd., Wiener Neudorf, Austria, 903120). The gastric phase digestion was performed at 37 °C for 2 h. During the simulated small intestinal digestion, the gastric phase was repeated and then the simulated small intestinal fluid was added to the sample. Like the gastric phase, the small intestinal digestion was also performed at 37 °C for 2 h in a shaking thermostat. The 2 h in vitro digestion at 37 °C simulates the physiological conditions of the human digestive system, where food spends approximately 1–2 h in the gastric and small intestine at body temperature before further digestion and absorption occurs in the intestines [26]. The enzymatic reaction was stopped by immediately cooling to −70 °C. The digested samples were evaluated using SDS-PAGE gel electrophoresis.

2.6. Microbiological Analyses and Storage Experiment

The mesophilic aerobic bacterial count was determined using TGE agar. To culture the microbes, the solid substrate and inoculum mixture were incubated in an inverted state at 37 °C for 24 h. After the HHP treatment, the samples were subjected to a 44-day storage experiment and stored at 4–6 °C until measurement. The sampling times were as follows: 0, 7, 14, 24, 34 and 44 days (~1.5 months). This period provides an opportunity to monitor any regrowth or stabilization of microbial populations and to more comprehensively assess the longer-term shelf life and quality of products. Short storage studies may not fully represent the extent of microbial proliferation, highlighting the need to extend observation periods [29]. The growth of microbial populations in the storage experiment was modeled using a linear regression equation. The observed data can be used to fit a regression model of the form y = mx + b, where the slope (m) corresponds to the growth rate of the microorganisms and the constant b gives the interception of the y-axis. The obtained R² value provides evidence of the adequacy of the fitted regression model [30,31].

2.7. Statistical Analysis

Statistical analysis was performed using IBM Statistics 22 software. One-way analysis of variances (ANOVA) was applied to discover significant effects in the cases of color and rheological parameters at 5% significance level (p < 0.05). The normality of the error terms was checked with a Kolmogorov–Smirnov test and the homogeneity of variances was evaluated using Levene’s test. Post hoc tests were used to further analyze the results in cases where the ANOVA test was significant. For homogeneous variances, the Tukey HSD post hoc test was employed, and for inhomogeneous variances, the Games-Howell test was used.

3. Results

3.1. Changes in Color

Table 1. The changes in the average values of the color (L*: lightness; a*: redness; b*: yellowness) of the HHP-treated blood plasma suspension and its color differences (ΔE*) compared to the control sample.

Pressure Levels [MPa]	L*	a*	b*	ΔE*
0	52.83 a ± 1.27	0.22 a ± 0.03	3.22 a ± 0.16	0
300	34.18 b ± 1.16	0.86 b ± 0.03	2.87 b ± 0.08	18.66
400	36.24 bc ± 0.88	0.81 bc ± 0.04	2.65 bc ± 0.14	16.60
450	38.50 cd ± 0.84	0.72 c ± 0.07	2.49 bc ± 0.06	14.35
500	38.24 cd ± 1.35	0.41 d ± 0.09	2.56 c ± 0.07	14.60
550	41.12 de ± 1.32	0.43 e ± 0.04	2.58 c ± 0.05	11.74
600	44.14 e ± 1.25	−0.47 e ± 0.05	2.62 c ± 0.08	8.73

^a–e Different letters show significant differences (p < 0.05).

shows the changes in the color factors of blood plasma suspensions after HHP treatment. The appearance of food, mainly determined by the color of the surface, is the first quality parameter that influences the consumer to accept or reject the food [32]. Based on the results obtained, it can be concluded that the application of pressure treatment induced significant changes in all color factors of blood plasma. Regarding the lightness (L*) factor, it can be observed that the pressure treatment darkened the samples compared to the control sample. However, a slight lightening was observed with increasing pressure values. Csehi et al. [33] examined HHP-treated bovine blood and found a significant decrease in L* at 300, 400 and 500 MPa, similar to our results.

In the case of a*, a reddish color was observed after treatment at 300 MPa, which decreases with increasing pressure values. At a pressure of 600 MPa, a* becomes negative and shifts towards the green tone. In the case of b*, it was observed that the initial yellowish color decreases and the color of the samples shifts towards blue with increasing pressure values. Majzinger et al. [34] treated large white swine and wild boar meat with HHP. They found a significant decrease in the b* color factor after 300 MPa treatment in both animals. This result is consistent with our results. The change is not significant between treatments above 450 MPa. The control sample is significantly different from all other pressure-treated samples for all three color factors. The changes in the color of the samples are presumably due to partial denaturation and aggregation of serum albumin, the main component of plasma proteins. The denaturation of this protein is associated with the unraveling of its native structure, leading to the exposure of hydrophobic regions and aromatic amino acids [35]. Larger agglomerates were formed at 550 MPa and 600 MPa. These structural changes can result in increased light absorption or scattering, which is reflected in the increasing color values of samples. Changes can affect the functional properties of blood plasma [36], including its solubility and binding capacity. According to ΔE*, it can be concluded that the values decrease with increasing pressure, but in all cases, the visually perceptible difference is in the ”very clearly visible” range (6.0 < ΔE*) [37].

3.2. Rheological Properties

From the shape changes of the flow curves of the HHP-treated blood plasma suspensions shown in Figure 1, it can be concluded that HHP treatment induced changes in the rheological properties of the blood plasma.

The flow index (n) values (Figure 1d) clearly indicate that the control and the samples treated at 300, 400, 450 and 500 MPa exhibit dilatational (shear-thickening) rheological behavior. Dilatational rheological behavior means that the viscosity of the material increases with an increasing shear rate [38]. The flow index of the sample treated at 500 MPa already shows a decrease, but the extent of this decrease is not significant. The sample treated at 550 MPa also has dilatational properties, but this sample is more like Newtonian fluids and significantly different from the other samples showing dilatational rheological properties, as well as from the sample treated at 600 MPa. Presumably, pressure treatments up to 550 MPa caused reversible changes in protein structures and molecular interactions. This led to increased viscosity and flow resistance [33,39]. The sample treated at the highest pressure is significantly different from the other samples and already exhibits pseudoplastic rheological behavior. In the case of this sample, the sample was already characterized by larger aggregates. In this sample, protein unfolding and aggregation disrupted the structural network, facilitating molecular alignment and reducing viscosity under shear stress [40]. The y-axis intercept of the flow curve gives the yield stress (τ₀) and provides information on whether a minimum shear stress value is required for the material to start flowing. Examining the yield stress values, it can be concluded that a slight decrease was observed in the sample treated at 300 MPa, and then higher values again characterize the samples treated at different pressure values. There is also a clear trend in the consistency coefficient (K) values, as samples treated at 550 and 600 MPa are significantly different from other samples and from each other, characterized by a higher consistency coefficient value. From this, we can conclude that the apparent viscosity values in these samples are also higher than in the control and in the samples treated at pressures lower than 550 MPa.

3.3. SDS-PAGE

The protein pattern of blood plasma suspensions treated with HHP between 300 MPa and 600 MPa is shown in Figure 2. The protein bands of blood plasma were identified according to the classification presented by Tarté [41].

The main band around 69 kDa corresponds to albumin. α-globulin was identified at 150 kDa, β-globulin at 48 and 52 kDa, and γ-globulin at 33 kDa. Based on Figure 2, it can be concluded that compared to the control sample, the application of 300–600 MPa pressure treatment did not cause any difference in the structure or quantity of proteins in the blood plasma. This form of blood plasma has a high resistance to pressure. One reason for this is presumably that the conformation of dried plasma proteins is no longer as “free” as in the fresh state but takes on a more rigid or aggregated structure. As a result, partially denatured proteins often become more resistant to external influences [42,43] and thus less intensively respond to high hydrostatic pressure treatments. Another reason may be that proteins rich in disulfide bonds, such as serum albumin (17 disulfide bonds) [44], are more stable under high pressure. These covalent bonds may help maintain the structure of the protein, making it less susceptible to pressure-induced denaturation [45].

3.4. Results of In Vitro Digestion

The digestibility of HHP-treated (450, 600 MPa) blood plasma suspensions was investigated in vitro digestion simulation using pepsin (gastric) and pancreatin (small intestine) enzymes. The effect of digestion on blood plasma proteins was monitored using SDS-PAGE (Figure 3).

Figure 3a shows that protein degradation has already occurred in the gastric phase. This means that the higher molecular weight proteins (albumin above 70 kDa, α-globulin) could not be identified in the control sample either, and they were completely degraded. The bands of β-globulin, γ-globulin and hemoglobin (residual) protein fractions identified in the control sample show high color intensity. The β-globulin was no longer identifiable at 450 MPa and was completely degraded. γ-globulin and hemoglobin were not completely degraded in the gastric phase. Their band intensities were reduced by pressure treatment compared to the control sample, indicating that the application of HHP treatment improved protein digestibility. HHP treatment modifies the structural integrity of plasma proteins by disrupting non-covalent interactions and altering secondary structures. These modifications result in protein unfolding and the increased exposure of hydrophobic regions, making them more susceptible to enzyme action during digestion. This phenomenon has been observed in various protein sources (cereals, legumes, nuts and dairy products) [46]. Cepero-Betancourt et al. [47] treated red abalone with HHP (200, 300, 400 and 500 MPa for 5 min). They found that HHP treatment improved the digestibility of abalone regardless of pressure level due to the partial unfolding of proteins. However, there is no difference in the gastric phase between samples treated at 450 MPa and 600 MPa, so it can be concluded that increasing the pressure values did not have a greater impact on the digestibility of blood plasma. The digestion of blood plasma in the small intestine (Figure 3b) shows that blood plasma proteins are completely degraded. The bands appearing on the gel image are the protein bands of the enzyme pancreatin used for digestion. Most of the processes that convert food into a form that the body can use occur in the small intestine [48]. Thus, based on the results, blood plasma can be considered an easily digestible source of protein, as evidenced by the following studies [49,50,51].

3.5. Microbiological Evaluation

The microbiological results of the HHP-treated blood plasma suspensions were evaluated according to the Hungarian Decree 4/1998 (XI. 11.) [52]. In general, two limit values are considered for the evaluation of the number of microorganisms, which are marked in Figure 4. The value “C” represents the compliance limit, and the value “R” indicates the rejection limit. A sample is compliant if it stays below the “C” level. It is acceptable if it meets or exceeds this level but stays below “R”. If it reaches or exceeds “R”, it is rejected [52].

Figure 4 shows the development of the mesophilic aerobic bacterial count of control and HHP-treated blood plasma samples during the 44-day storage period. A decrease in the number of mesophilic aerobic bacteria measured on day 0 was observed because of HHP treatment. Compared to the control sample (3.28 log CFU/mL), the microbial number of the sample treated at 600 MPa was reduced by half (1.68 log CFU/mL). Patil et al. [53] investigated the effect of non-thermal technologies (PEF, UV-C) like HHP on the microbial load of Asian seabass gills. They found that the application of high PEF intensity (17.5 kV) for 5 min reduced the initial microbial load from 8.0 log CFU/g to 5.5 log CFU/g. Subsequent UV-C exposure for 15 min further decreased the microbial count to 3.0 log CFU/g. This means that the application of these non-thermal technologies effectively contributes to the shelf life of food critical for food safety, enhancing consumer health safety.

Figure 4 shows that the control sample exceeded the rejection limit on the last day of storage. The HHP-treated samples were all below the “R” limit. The HHP-treated samples at 550 and 600 MPa did not exceed the “C” value. HHP effectively inactivates mesophilic aerobic microorganisms by disrupting their cellular structure, including membranes and proteins, leading to cell death [54]. The rate of microbial inactivation increases with increasing pressure levels. Based on the slope indicators obtained from the equation of straight lines, it can be concluded that in the case of a sample treated at the lowest pressure value (300 MPa), there is already a decrease in the growth of the surviving microbes. For samples treated at 400 MPa and 450 MPa, there is no difference in the slope, so in this case, a 50 MPa pressure increase has no effect on microbial growth. In the case of the sample treated at 600 MPa, a 29% decrease in the growth rate of microorganisms was observed compared to the control sample. A different conclusion was reached by Pares et al. [55], who treated fresh porcine blood plasma for 15 min at 450 MPa at different temperatures (5 °C, 25 °C and 40 °C). They found that treatments at 5 °C reduced the microbial counts by 90% and reduced the ability of surviving microorganisms to reproduce by 20–50%.

4. Discussion and Future Perspectives

The recommended HHP treatment conditions to maximize the functional properties of rehydrated animal blood plasma for food applications are between 300 and 600 MPa, with a treatment time of 5 min. These conditions help to improve the solubility, gelation and emulsifying properties while minimizing protein denaturation. Lower pressures (300–400 MPa) improve solubility and emulsification, while higher pressures (500–600 MPa) enhance gel strength.

The 450 MPa HHP treatment is likely to improve the bioavailability of essential amino acids by improving protein digestibility and structural modifications to enzymatic breakdown. This could lead to better absorption and utilization of key nutrients in real-world consumption scenarios, potentially improving the nutritional quality of blood plasma-based ingredients in functional foods or supplements. Enhanced digestibility may also support improved protein efficiency, making HHP-treated plasma a valuable source of high-quality protein for various dietary applications.

HHP as a non-thermal processing technique shows significant potential for maintaining the functional and microbiological quality of blood plasma in the food industry. Comparative studies show that the effect of HHP on the microbiological quality and physicochemical properties of the juices is similar or better than other non-thermal techniques, such as pulsed electric fields (PEF) and ultraviolet (UV-C) treatment [56]. HHP is particularly effective in inactivating microorganisms while preserving the structural and functional properties of serum and serum products, making it suitable for applications requiring high microbiological safety without compromising product quality [57]. This makes HHP an excellent alternative to plasma processing, balancing microbial safety and functional integrity.

The use of HHP in the processing of blood plasma contributes to sustainable food systems by extending the shelf life of plasma-derived products and reducing the amount of waste. It helps to safely process by-products of the meat industry, which are often discarded, promoting circular bioeconomy practices. By increasing the use of plasma in food and animal feed, HHP technology reduces the environmental impact of food production and supports resource-efficient practices. This process aligns with sustainability goals by minimizing waste and optimizing the use of all biological materials.

Comparative studies of different types of animal plasma sources (bovine, porcine and bird) under varying pressure–time–temperature conditions help to determine the optimal processing parameters. To optimize HHP parameters, in addition to protein denaturation, gelation properties, microbial inactivation and evaluation of functional properties, emphasis should also be placed on the bioavailability, allergenicity and effect of HHP-treated plasma on organoleptic properties. By examining these properties, we can obtain more comprehensive information on the food market applicability and viability of HHP-treated rehydrated plasma. Furthermore, this technology can be extended to other underutilized protein sources (e.g., insect proteins, seaweed, microalgae, fungal proteins, hemoglobin), so these alternative protein sources could offer a more sustainable approach to meeting the growing demand for protein.

5. Conclusions

In this study, it was determined that a stable and safe product from a food safety perspective can be produced at a pressure of 550 MPa for the use of blood plasma suspensions as a liquid, fluid material. If the plasma suspension is treated at pressures higher than 550 MPa, it is possible to produce products with a gel and pudding consistency. In addition, the use of HHP technology as a means of improving the digestibility of foods is recommended at a maximum pressure of 450 MPa.

In terms of the overall results obtained, it was concluded that products produced in this way and under these conditions could become a useful part of the food market and that appropriate communication could make consumers aware of the benefits and opportunities offered by products produced in this way.