In the biotechnology, biopharmaceutical, bioenergy, food, and feed industries, the efficient recovery of intracellular compounds is a critical step throughout R&D and large-scale production. Intracellular products such as proteins, lipids, and pigments define the core value of bio-based products and directly influence the functionality, stability, and economic viability of final formulations. Taking fermentation processes as an example, microorganisms including bacteria, yeast, and algae are widely used to synthesize high-value intracellular substances: algal proteins are emerging as important raw materials for animal feed and nutritional supplements, microbial lipids can be converted into renewable biofuels, and various natural pigments and functional proteins show broad prospects in pharmaceuticals, food, and cosmetics. However, most of these target products are “encapsulated” within rigid cell walls or membranes. How to achieve efficient and controllable cell disruption and product release while preserving product activity and integrity has become an unavoidable technical challenge in downstream processing.
Among various cell disruption techniques, high-pressure homogenization (HPH) has evolved from traditional emulsification and homogenization applications to become one of the core methods for extracting intracellular compounds. By applying instantaneous high pressure, HPH forces cell suspensions through a narrow homogenization valve channel within an extremely short time, generating intense shear forces, impact forces, and cavitation effects. These combined physical actions act on cellular structures to effectively disrupt cell walls and membranes. Unlike extraction methods relying on chemical solvents or biocatalysis, HPH is a purely physical process that introduces no additional chemicals. It avoids solvent residues that compromise product safety and significantly reduces environmental burden, aligning with the current trend toward green and sustainable biomanufacturing.
Notably, HPH offers distinct advantages in efficiency, scalability, and process controllability. By adjusting homogenization pressure, cycle number, and processing temperature, operators can precisely disrupt different microbial cells (e.g., Gram-negative bacteria, Gram-positive bacteria, yeast, or algae). This ensures sufficient release of intracellular compounds while minimizing damage to the structural integrity and biological activity of target products. For industrial production, this “parameter-adjustable, result-predictable” characteristic is particularly valuable: disruption protocols established at the laboratory scale can often be smoothly scaled up to pilot and commercial production without radical process modifications.
As biomanufacturing demands higher yields, lower costs, and greater sustainability, HPH is increasingly applied in extracting intracellular proteins, recovering microbial oils, and releasing natural pigments. It not only provides an efficient alternative to traditional chemical and enzymatic methods but also reshapes cell disruption—a “fundamental yet critical” downstream unit operation. In the following sections, we further explore how this technology unlocks greater value in modern bioprocessing by examining its working principles, key influencing factors, and performance across diverse cell systems.
Working Principle of High-Pressure Homogenization
HPH is a physical cell disruption method with a straightforward basic principle, yet it features high integration in engineering design and energy utilization, enabling intense yet controlled disruption of cellular structures in milliseconds. In a typical HPH process, a cell suspension is pressurized by a high-pressure pump and forced through a precision-engineered homogenization valve with an extremely narrow gap. As the suspension passes through the valve orifice at high speed and undergoes instantaneous pressure release, multiple intense physical effects occur simultaneously within the system.
First, the rapid pressure drop and velocity change generate significant shear forces in the liquid, a primary driving force for breaking cell walls and membranes. Second, strong turbulence created by high-speed flow in the narrow channel causes frequent collisions between cells, as well as between cells and equipment inner walls, further weakening cellular structural integrity. Additionally, cavitation occurs in local low-pressure zones—namely, the formation and instantaneous collapse of microbubbles—which releases substantial energy and delivers extra mechanical impact to cell walls. The synergistic combination of shearing, impact, and cavitation allows HPH to efficiently disrupt various cell types without chemical reagents or biocatalysts.
Compared with other cell disruption methods, HPH excels in process controllability and scalability. By tuning homogenization pressure, cycle number, and feed concentration, it can flexibly adapt to bacterial, yeast, algal, and other cell systems. It achieves sufficient release of intracellular proteins, lipids, or pigments while preserving the structural stability and bioactivity of target products. Thanks to its stable, continuous, and easily scalable working principle, HPH has become a highly competitive cell disruption solution for downstream processing in modern biomanufacturing.
Applications of HPH in Intracellular Product Extraction
Extensive research and industrial experience confirm that, with appropriate pressure settings and homogenization cycles, high-pressure homogenizers can effectively break cell walls or membranes to achieve high-efficiency release of proteins, lipids, pigments, and other high-value intracellular products. HPH is particularly mature in microalgae applications. Researchers have used HPH to disrupt Porphyridium cruentum for extracting intracellular β-phycoerythrin and functional proteins, systematically investigating the effects of operating pressure and cycle number on disruption efficiency. Results showed that at pressures near 1000 bar, chloroplast membranes were only moderately damaged, allowing partial release of cytoplasmic water-soluble proteins but limited release of chloroplast-localized β-phycoerythrin. When pressure exceeded 1000 bar, cell and chloroplast membranes were effectively disrupted, leading to a marked increase in β-phycoerythrin release. This indicates that HPH not only achieves cell disruption but also enables “fine control” over the release of different intracellular components via pressure regulation, providing process flexibility for targeted product recovery.
Similar findings were reported in studies on Chlorella kessleri, a microalga rich in proteins, carbohydrates, and lipids and a promising functional feedstock. Microalgal suspensions were subjected to multiple HPH treatments at approximately 400 bar, 800 bar, and 1200 bar. Results demonstrated a significant upward trend in protein release with increasing pressure and homogenization cycles, fully reflecting the efficiency of HPH in disrupting microalgae with robust cell walls and highlighting pressure and cycle number as key parameters affecting extraction performance.
Response to HPH varies across microalgal species, closely correlated with cell wall composition and thickness. For instance, red microalgae possess complex, thick cell walls composed of cellulose, xylan or mannan fibers, and abundant matrix polysaccharides, typically requiring higher operating pressures for effective disruption. In contrast, green microalgae (e.g., Chlorella or Chlorella-like species) have cell walls mainly composed of cellulose and partial proteins, making them more susceptible to mechanical damage. This explains why industrial HPH applications often require customized parameter designs for different algal strains.
Beyond microalgae, HPH performs well in disrupting yeast and bacterial cells. Studies have shown that treating Saccharomyces cerevisiae at approximately 800 bar effectively disrupts its cell walls (primarily composed of β-glucan and chitin), enabling efficient release of intracellular proteins. Other research has combined HPH with physical pretreatment methods to weaken cell wall structures prior to homogenization, improving overall disruption efficiency while reducing required homogenization pressure—a strategy with potential for lowering energy consumption and protecting thermosensitive products. In near-industrial applications, HPH has been successfully used to extract bio-based materials from recombinant Escherichia coli, demonstrating its potential for continuous, large-scale production.
Across cell types, the pressure required for HPH correlates closely with the mechanical strength of cell walls or membranes: microalgae, with the thickest cell walls, demand the highest pressure; yeast requires moderate pressure; and bacteria, with lower mechanical resistance, need the lowest pressure. This “adjustable, scalable, adaptable” nature establishes HPH as a core cell disruption technology across biopharmaceuticals, biofuels, functional foods, and other sectors.
Challenges and Solutions in HPH-Based Cell Disruption
While HPH is an optimized choice for cell disruption, it inevitably faces technical and engineering challenges in practical applications. These challenges do not negate the value of HPH but highlight the need for systematic optimization and combined strategies to unlock its full potential during process design and scale-up.
First is the issue of disruption selectivity. Compared with chemical methods such as solvent extraction, HPH is a non-selective physical disruption process. At high pressures typically ranging from hundreds to thousands of bar, cells are completely disrupted under combined shear, turbulence, and cavitation, simultaneously releasing intracellular proteins, lipids, nucleic acids, and cell debris. Although this “full release” boosts overall target product recovery, it increases the burden of downstream clarification, filtration, and purification. A feasible solution is to enhance “process controllability” through refined process design rather than simply pursuing higher pressure. For example, adjusting homogenization pressure, cycle number, and feed concentration can achieve “selective disruption” to a certain extent, preferentially releasing cytoplasmic components while avoiding excessive damage to organelles. Additionally, coupling HPH with membrane filtration, centrifugation, or continuous clarification systems allows simultaneous removal of large debris post-disruption, reducing downstream separation difficulty.
Second is energy consumption. HPH requires sustained high pressure and flow velocity, leading to considerable power consumption during continuous industrial operation. This issue is often negligible at the laboratory scale but directly impacts operating costs and carbon footprint in pilot and commercial production. An effective countermeasure is to improve overall efficiency by “reducing ineffective energy consumption”. For instance, integrating mild pretreatments (e.g., gentle enzymatic hydrolysis, osmotic stress) can partially weaken cell walls/membranes before HPH, enabling equivalent disruption efficiency at lower pressures (e.g., from 1200 bar to 800 bar). Furthermore, equipment optimization (e.g., valve seat design, flow channel refinement) and the adoption of intelligent control systems help reduce energy consumption per unit product while maintaining disruption efficiency.
Third, heat generation during HPH is a major limiting factor. Mechanical energy rapidly converts to thermal energy under high-pressure, multi-cycle conditions, elevating feed temperature. This can cause denaturation or activity loss of thermosensitive products such as enzymes and therapeutic proteins. Mature solutions include integrating in-line cooling modules (e.g., heat exchanger cooling) and optimizing process routes to reduce unnecessary cycles. In practice, a “moderate pressure + fewer cycles” strategy is increasingly adopted to balance disruption efficiency and thermal accumulation within acceptable limits, ensuring both yield and product quality.
Finally, techno-economic analysis and life cycle assessment should be incorporated early before scaling HPH to industrial production. By systematically evaluating the cost, energy consumption, and environmental impacts of different pressure strategies, equipment configurations, and operating modes, enterprises can rationally balance “higher recovery” and “lower operating costs” to select the most sustainable technical route.
Conclusion
Overall, HPH is emerging as one of the most representative physical disruption technologies for intracellular compound extraction. Compared with traditional methods relying on organic solvents or enzymatic reactions, HPH achieves cell disruption through purely physical action, offering high efficiency, continuous operation, and excellent scalability. It reduces environmental burden while enabling efficient recovery of proteins, lipids, and other high-value products. Importantly, the technology is mature and reliable, with proven applications in food, biotechnology, pharmaceuticals, and other industries. With ongoing improvements in equipment performance, the integration of automation and digitalization, and synergistic use with other pretreatment and separation technologies, HPH will further unlock its potential in enhancing product quality stability and reducing overall costs. It is foreseeable that, as biomanufacturing advances toward greener and larger-scale production, HPH will play an increasingly critical supporting role in intracellular compound extraction.
