Homogenization is a sophisticated method of achieving substance uniformity by altering and reducing particle sizes. Homogenization methods often include different processes, such as mixing, high-pressure processing, disrupting, emulsifying, dispersing, and stirring of samples (Dhankhar, 2014). Interestingly, the concept of homogenization dates back to 1899 when Auguste Gaulin acquired a patent on his homogenizing machine utilized to treat milk. Note that Gaulin’s invention consisted of a three-cylinder pump and hair-like tubes.
Today, homogenizers can be used for size reduction, as well as shredding, extraction, wetting, and blending of different materials (e.g., fibrous products, hard samples). Such laboratory instruments are invaluable in numerous settings, including pharmaceutical research, medicine, life science, cosmetics, industrial processing, and quality control.
Given the fact that homogenization principles are employed in various settings, it’s no surprise that homogenizers are invaluable tools. Homogenizers employ different high-speed and high-pressure methods to reduce particles to 0.1-2 microns and blend them in a stable emulsion for further use. Homogenization is one of the first stages preceding laboratory extraction or scientific analysis. For instance, quantifying the amount of a substance via mass spectrometry can be accomplished only when the sample is completely homogenized. Scientific homogenizers can effectively process a broad range of samples, such as muscle tissue, cardiac tissue, food, and plant materials (Yacko-Archilbad, 2015).
That being said, different types of homogenizers are needed for different analyses (e.g., DNA extraction), with rotor/stator or colloid mills, high-pressure units, and sonic disruptors being some of the most common homogenizers. Note that rotor/stator homogenizers used knives to shred large quantities of material, while high-pressure homogenizers are often used with liquids, especially when homogenizing milk. Ultrasonic devices, on the other hand, generate intense ultrasonic waves (18 to 50 kHz) that exert pressures over 500 atmospheres and 5,000°C. We should note that ultrasonic homogenizers are based on the principle of cavitation by inserting and invigorating a high-grade Titanium probe into a fluid. The vibrations at the tip of the probe create vapor bubbles that implode, producing microscopic shock waves to break the existing covalent cell bonds.
Bead mill homogenizers, on the other, depend on the mechanical association amongst beads and secured tubes. Given the fact that the utilized beads exert force on the sample, an essential feature is the material used for the beads. Beads can be ceramic/zirconium, garnet, stainless steel, glass, or carbide. While ceramic beads are perfect for preparing delicate specimens (e.g., liver tissue), garnet beads with their pointed ends are mainly intended for handling soil. Additionally, stainless steel beads are appropriate for preparing both dry and hard specimens, whereas glass beads are perfect for handling microbial specimens (from gram-positive to gram-negative bacteria). Finally, we should note that carbide beads are ideal for extricating RNA from microbial specimens and soil (Buxton, 2011).
Apparatus and Equipment
Among the wide variety of homogenizers, the microtube homogenizer is one of the most prominent homogenizers used in lab settings to process various samples, such as tissue, food, and soil. This homogenizer uses intensive speed and a three-dimensional shaking technique to disintegrate up to 24 samples at once.
The microtube homogenizer apparatus typically comprises a brushless motor that supports maintenance-free processing and reduced motor noise. The unit’s small footprint and high-velocity force present small to medium laboratories a convenient option as compared to larger, more costly homogenizers. The microtube homogenizer has the following dimensions: 11”W x 14.2”D x 15.2”H (28 x 36 x 38.5 cm) and weighs 55 lbs (25 kg). The capacity of the microtube homogenizer is 24 x 2.0 ml tubes, and its noise level is under 68 dB. This equipment can maintain a speed of 4.00 to 7.00 m/s in 0.05 increments; it has an acceleration/deceleration rate of ≤ 2 seconds. The unit works with a cycle time of 1-90 seconds in 1-second increments with pauses between cycles of 0-2 minutes in 1-second increments; note that the number of cycles per program is 1-10. Last but not least, we should mention that the homogenizer is suitable for 100-240 V, 50-60 Hz, 600 W input.
How to Use
Microtube homogenizers can be used to process various materials, such as plant tissue, food, and soil. As explained above, such units make use of rapid speeds and three-dimensional shaking techniques to disrupt several samples at a time.
Note that the main programming steps involve choosing the speed, time, number of cycles, and desired pauses between cycles, and then pressing “Start.” Approximately 50 programs may be saved for future processing; to optimize processing times, the last programmed specifications remain in the settings.
What Are Its Uses
Food and dairy applications of homogenization
Homogenization is a fundamental procedure in food and dairy processing. Homogenization, particularly high-pressure processing, is used to make products (e.g., sauces) stable and with an enhanced texture; the desired effect is achieved by forcing the substance through a homogenizing valve under extreme pressure. One of the most renowned usages is milk homogenization. The main purpose of milk homogenization is to counteract segregation, generally creaming, by reducing the size of the fat globules. Three factors play a crucial role: a reduction in the mean diameter of the fat globules (a factor in Stokes Law), a reduction in the size distribution of the fat globules, and an increase in the thickness of the globules due to protein absorption. Note that heat pasteurization can separate the cryo-globulin complex that tends to cluster fat globules.
Cosmetic applications of homogenization
Homogenization is a vital factor in maintaining the quality and stability of beauty products, lotions, nail varnishes, shampoos, toothpaste, and emulsions containing distinctive oils. High-pressure processing, for instance, can improve a product’s texture and consistency under states of extreme pressure, shear, and stress. High-pressure homogenization guarantees the most proficient utilization of the active ingredients in any beauty product, which can diminish costs.
Biotechnology applications of homogenization
Homogenization is used within biotechnology settings. High-pressure homogenization, in particular, is generally utilized for cell rupture (cell rupturing, cell disruption). The main purpose is to discharge intercellular substances (for example, proteins) that are found in high concentrations in different organisms (for example, yeasts). High-pressure homogenizers are exceptionally useful and proficient for cell breaking tasks and can increase the yield from an important source while maintaining the quality of the product at an extremely high level.
Homogenization in pharmaceutical settings
Homogenization (referred to in the pharmaceutical business as micronization) is the method of decreasing the particle sizes of pharmaceutical items (under intense pressure, shear, turbulence, acceleration, and impact) in order to increase their stability and efficiency. Note that when emulsions, suspensions, or solutions are drawn into a high-pressure homogenizer, the sample is forced through a special homogenization valve at a high degree of pressure. Note that particles around 500 micrometers in size can be reduced to 0.4-1 micrometers depending on the particular application.
Homogenization in chemical processing
Although high-pressure pumping and homogenization get less publicity in chemical settings, their applications are numerous. Homogenization is ideal for making stable emulsions, dispersions, and mixes. The subdivision of particles and droplets improves their open surface area, which can enhance chemical reactions by decreasing response times and temperatures. Also, the use of high-pressure processing improves extraction procedures, as well as the color intensity in paints. Last but not least, homogenization is utilized in the petrochemical business for additive blending and viscosity testing.
Evaluation of the effectiveness of various disruption techniques on yeast cell wall preparations
Bzducha-Wrobel et al. (2014) investigated the effect of different yeast cell disruption methods for cell wall preparation. The research team investigated the effect of hot water extraction (autoclaving), thermally-induced autolysis, homogenization with the use of a bead mill, sonication, and a mix of these techniques. Note that the experimental systems were set in water (pH 5.0 and pH 7.0) and Tris-HCl buffer (pH 8.0). Interestingly, the yeast cell wall preparations of Saccharomyces cerevisiae – with the highest level of cytosol component discharge and purification of β-glucans – were delivered within 30 minutes of cell homogenization using zirconium-glass beads (with a diameter of 0.5 mm). The team concluded that homogenization in a bead mill is ideal for general isolation procedures as it allows researchers to reduce the autolytic activity of yeast strains.
Evaluation of a mouse model of paralytic myelitis caused by enterovirus D68
Hixon et al. (2017) studied the relation between acute flabby myelitis (AFM) in adolescents and enterovirus D68 (EV-D68) in mice. The study aimed to produce an effective mouse model by selecting EV-D68 strains to simulate neurological illness, using Bead microtube homogenizer. Results showed that homogenization could be a beneficial technique in the evaluation of different exploratory models used to investigate EV-D68 produced myelitis, as well as neurological treatment research.
Evaluating protein extraction from soft tissues utilizing the Fisher Scientific Bead Mill 24
Easparro (2017) evaluated protein extraction and isolation from soft tissues, such as brain and liver samples, via mechanical homogenization. The research team used the Bead Mill 24- and 2-ml soft tissue homogenizing mix to assess their productivity and reliability. As explained above, bead mills employ high-speed shaking within a sealed tube filled with beads. Bead Mill 24, in particular, can process up to 24 tissue samples per cycle. The results showed that the Bead Mill 24 could be used for homogenizing soft tissue samples (in less than 30 seconds) to obtain adequate protein yields, which is invaluable in proteomic studies and genome sequencing.
Strengths and Limitations
Homogenization has numerous benefits. Microtube homogenizers, in particular, are invaluable in research, tissue homogenization, cell disruption, and extraction. The major advantage of using a microtube homogenizer is that bead mill technology can process an extensive range of specimens over a short time (e.g., cyanobacteria, yeast, spores, and microalgae). Liver, lung, brain, and other soft tissue samples, for example, can be homogenized quicker with a bead mill than with an ultrasonic homogenizer. Note that the size of the beads should be appropriate to the sample of interest.
While homogenization is invaluable in research, there are a few limitations. One of the disadvantages of microtube homogenization, in particular, is that tubes and beads have to be cleaned and stored accordingly to avoid contamination and tearing. That said, bead homogenization is still one of the most powerful laboratory processes.
Homogenization is a powerful technique used to achieve homogeneity by altering particle sizes. Homogenization covers a vast area of processes, such as high-pressure processing, mixing, disrupting, emulsifying, and dispersing of samples. The applications of homogenization can benefit numerous settings, including the food and dairy industry, cosmetics, biotechnology, and pharmaceutical settings. Additionally, homogenizers can be used in medical research for yeast cell wall preparations and proteomic studies.
Note that there are different homogenizers suitable for different applications, with colloid mills, high-pressure units, and sonic disruptors being popular units. The microtube homogenizer, in particular, is one of the most beneficial lab instruments. It makes use of high speeds and a three-dimensional shaking technique to disintegrate samples. As stated earlier, the microtube homogenizer apparatus typically has the following parameters: speed rates of 4.00 to 7.00 m/s in 0.05 increments, acceleration/deceleration rates of ≤ 2 seconds, capacity of 24 x 2.0 ml tubes, 1-10 cycles per program, noise levels under 68 dB, and electrical specifications of 100-240 V, 50-60 Hz, 600 W. Given its parameters, this homogenizer can be used for different samples, such as brain tissue, spinach leaves, and soil.
- Buxton, A. (2011). Bead mill benefits outweigh ultrasonic homogenizers. Retrieved from https://www.laboratoryequipment.com/article/2011/09/bead-mill-benefits-outweigh-ultrasonic-homogenizers
- Bzducha-Wrobel, A., Blazejak, S., Kawarska, A., Stasiak-Rozanska, L., Gientka, I., & Majewska, E. (2014). Evaluation of the Efficiency of Different Disruption Methods on Yeast Cell Wall Preparation for β-Glucan Isolation. Molecules, 19, p. 20941-20961.
- Dhankar, P. (2014). Homogenization fundamentals. IOSR Journal of Engineering, 4(5), p. 1-8. DOI: 10.9790/3021-04540108
- Easparro, B. (2017). Protein Extraction from Soft Tissues using the Fisher Scientific Bead Mill 24.
- Hixon, A., Yu, G., Leser, J., Yagi, S., Clarke, P., Chiu, C., & Tyler, K. (2017) A mouse model of paralytic myelitis caused by enterovirus D68. PLoS Pathog, 13(2).
- Yacko-Archibald, H. (2015). Bead mill or mechanical homogenizer. Retrieved from https://www.linkedin.com/pulse/bead-mill-mechanical-homogenizer-holly-yacko-archibald