Influence of operating conditions on membrane fouling in crossflow microfiltration of particulate suspensions

The effects of the operating conditions on the crossflow microfiltration (CFMF) of particulate suspensions were investigated. Lactalbumin particles were used as the feed material. Experiments were carried out in constant transmembrane pressure (TMP) mode using tubular ceramic membrane modules. All important parameters (internal and surface fouling, cake mass, height, porosity, and particle size distribution (PSD)) were estimated to provide a more complete understanding of the process than has been attempted before. Lactalbumin particles which are highly irregular in shape and widely size distributed formed an adhesive cake on the membrane surface during CFMF. The porosity and particle size of the deposited cake decreased with time of filtration. The value 100 kPa was found to be optimum with respect to the permeate flux in the studied range of TMP. Particle size classification effects of TMP and crossflow velocity (CFV) were demonstrated. The results of this study provided a possible explanation to the contradictory reports on the effect of CFV on the steady-state flux and the time required to obtain it. Significantly, the internal fouling first decreased with increasing CFV and then increased above 1.5 m s⁻¹. This is attributed to the particles size classification effect of CFV. A process was developed based on the observed effects of the operating parameters on the CFMF performance that enables operation at very low internal fouling and high flux for as long as 160 min. The developed process has the potential to become commercial if coupled with backflushing.     

Use of response surface methodology to optimise the hydrolysis of whey protein isolate in a tangential flow filter membrane reactor

Response surface methodology (RSM) was used to investigate the effects of substrate concentration (S), enzyme concentration (E) and initial permeate flow rate, (J_i), on permeate flux behaviour in a 10 kDa nominal molecular weight cut-off (NMWCO) tangential flow filter (TFF) enzyme membrane reactor (EMR) during 3 h hydrolysis of whey protein isolate (WPI) using Protease N Amano (IUB 3.4.24.28, Bacillus subtilis) at pH 7.0 and 45 °C. The average residual permeate flow rate (J_residual), residual enzyme activity (A_residual) and product recovered in permeate designated as apparent sieving (S_apparent) were monitored. The quadratic model regression equations obtained revealed that all the three factors had significant but dissimilar influences on permeate flux behaviour. J_residual, S_apparent and A_residual increased with increasing E, A_residual decreased with increasing J_i and there was substrate inhibition at low E. The optimised factors were S = 4.72% (w/v), E = 0.055% (w/v; hence E/S ≈ 1% w/w) and J_i = 6.91 mL/min (approximately 0.7% reactor volume per minute). The optimised values were 87.24%, 52.37% and 35.08% for J_residual, A_residual and S_apparent, respectively. The actual values for the responses agreed well with the predicted values implying that RSM is suitable for EMR optimisation. Covariance values showed that J_residual and S_apparent increased concomitantly while A_residual decreased with increasing S_apparent and J_residual.     

Diffusion of thiocyanate and hypothiocyanite in whey protein films incorporating the lactoperoxidase system

The diffusion of the thiocyanate (SCN⁻) and hypothiocyanite (OSCN⁻) components of a lactoperoxidase system (LPOS) in whey protein isolate (WPI) films was investigated. Diffusion coefficients for these molecules were measured for the LPOS-incorporated WPI films prepared with different WPI:glycerol ratios (1:1, 3:1, and 5:1). WPI film disks were coated on the surfaces of smoked salmon samples, and the samples were stored at 4, 10 and 22 °C. The diffusion coefficients were determined by fitting a mathematical model to the amounts of SCN⁻ and OSCN⁻ released from the disks during a period of time. The diffusion coefficients for SCN⁻ (D₁) and OSCN⁻ (D₂) in the films were 0.19–5.2 × 10⁻¹² m² s⁻¹ and 0.13–6.5 × 10⁻¹³ m² s⁻¹, respectively. The D₁ and D₂ decreased as the WPI:glycerol ratio increased and the storage temperature decreased. The E_a values for diffusion in 1:1, 3:1, and 5:1 WPI:glycerol films were 13.3, 29.5, and 35.6 kJmol⁻¹, respectively, for SCN⁻ and 15.8, 30.1, and 39.9 kJmol⁻¹, respectively, for OSCN⁻.     

A new measure of uptake: desorption of unreacted phosphine from susceptible and resistant strains of Tribolium castaneum (Herbst) (Coleoptera: Tenebrionidae)

Previous studies of phosphine (PH₃) uptake by insects have concentrated on the process as a whole (“gross uptake”), without distinguishing between absorption of the gas and oxidation to non-volatile products. The lower gross uptake by phosphine-resistant (R) strains of stored product pests has given some insights into resistance mechanism(s). In this study, a recently described method of fumigant residue analysis in grains (microwave irradiation followed by headspace gas chromatography) was adapted to measure absorbed unreacted PH₃ (“reversible uptake”) in a susceptible (S) and an R strain of the rust red flour beetle Tribolium castaneum. At a concentration of 0.9 mg l⁻¹, S insects contained 20 ng g⁻¹ after 15 min exposure, rising slowly to 50 ng g⁻¹ after 5 h. The R strain yielded 190 ng g⁻¹ after 15 min, falling to 50 ng g⁻¹ over 5 h. Falling PH₃ content corresponded with increasing mortality in the R strain, while all except the shortest exposure killed 97% or more of the S strain. Insects of either strain, killed prior to PH₃ exposure by freezing in liquid nitrogen, contained 130–140 ng g⁻¹ after 30 min, rising to 190–200 ng g⁻¹ after 5 h. Gross uptake under the same conditions was 50 μg g⁻¹ (S) and 8 μg g⁻¹ (R) after 5 h, which accords with the literature. Reversible uptake by living insects of either strain under anoxia was 40–50 ng g⁻¹ over 30 min to 2 h. By examining the time-course of reversible PH₃ uptake, a new hypothesis of phosphine action and uptake, in which PH₃ oxidation in vivo is a consequence of reactive oxygen species generation, rather than a direct cause of toxicity, is discussed.     

Changes in blocking mechanisms during membrane processing of pomegranate juice

The effect of pressure, velocity, pretreatment, membrane type and pore size on fouling mechanisms were evaluated. Pomegranate juice was treated with polyvinylidene fluoride (PVDF) 0.22 μm and mixed cellulose ester (MCE) 0.1 μm at different pressures. Cake formation which was the dominant mechanism was formed in the first stages of process and, as the filtration proceeded, intermediate, standard, and complete blocking, respectively occurred at higher pressure (5 kPa). At lower pressure (0.5 kPa) the last mechanism did not occur. Results showed that cake formation was the only mechanism in MCE 0.22 μm, however, others occurred with MCE 0.1 μm and PVDF 0.22 μm. Using MCE 0.22 μm prior to MCE 0.025 μm can reduce the role of cake formation in pore blocking. Evaluation of the impact of velocity showed that at the higher velocity (0.53 m s⁻¹) the complete blocking occurred faster than at the lower velocity (0.09 m s⁻¹).     

Fouling Analysis and Performance of Tubular Ultrafiltration on Pretreated Olive Mill Waste Water

This study deals with the performance of a tubular ultrafiltration system on sieved and centrifuged olive mill waste water. A generalized statistical model was developed describing the impact and the relative importance of major experimental parameters (membrane pore size, transmembrane pressure, feed flow rate, and feed temperature) on permeate flux. According to this model, process pressure appeared to have the largest impact on permeate flux, followed by process temperature. As membrane treatment of such a difficult material largely depends on fouling, a systematic analysis of prevailing fouling mechanisms was also run. Despite sieving and centrifugation of the original waste, membrane fouling caused a flux decline of 60–65% within 15–20 min. Internal fouling, pore blocking, and cake layer formation were all responsible for membrane fouling during the first 40 min of operation. After that period, cake formation appeared to play a predominant role. Based on the proposed generalized model, the relative importance of process parameters can be evaluated and process performance can be improved by proper interventions. Independent of membrane size, fouling is a serious problem to be resolved. The qualitative performance of this process, including chemical oxygen demand distribution, polyphenol profile, and antioxidant capacity, is discussed in a separate paper.     

Low cross-flow velocity microfiltration of skim milk for removal of bacterial spores

The use of microfiltration membranes in the dairy industry to remove bacterial spores has been applied for some time using the so-called “bactocatch” process. However, these microfiltration units have high energy demands since high linear velocities are required during operation, to avoid problems related to fouling and concentration polarization. In this work, optimization of a backflushing technique combined with reverse asymmetric membranes (‘backshock’ technique) was used to avoid the fouling and concentration polarization problems, allowing the use of low linear velocities and resulting in low-energy costs. In the novel ‘backshock’ technique, the permeate is pressurized during a very short time interval (less than 1 s) and with a frequency around 0.2-1 s⁻¹. The benefit of using a reverse asymmetric membrane is related to the formation of a very open fouling layer just inside the porous support layer and the build-up of a concentration profile of the proteins inside the porous structures. The microfiltration of skim milk using ceramic and polymeric membranes was studied with different membrane structures. The backshock technique, combined with reverse asymmetric membranes of pore size of 0.87 μm, allows the effects of concentration polarization and fouling to be controlled, achieving very high (500 L h⁻¹ m⁻²) and stable fluxes with 100% casein transmission and a high retention of spores (reduction by a factor 10⁴-10⁵) even at low linear velocities (0.5-1 ms⁻¹).     

Meat quality characteristics of springbok (Antidorcas marsupialis). 1: Physical meat attributes as influenced by age, gender and production region

Springbok is the most extensively cropped game species in South Africa. The effects of age (adult, sub-adult, lamb), gender and production region on the physical attributes (pH₂₄, cooking and drip loss, Warner Bratzler shear force and colour) were determined using samples of the M. longissimus dorsi (LD) muscles of 166 springbok. Stressed animals had a higher (P < 0.05) pH₂₄ (6.3 ± 0.07), as observed in the meat originating from the Caledon region. This meat had lower (P < 0.05) cooking loss (27.2 ± 0.62%) and drip loss (1.8 ± 0.08%) values in comparison to meat originating from the other regions. Inverse correlations were noted between pH₂₄ and drip loss (r = −0.26, P < 0.01) and cooking loss (r = −0.42, P < 0.001). Shear force values (kg/1.27 cm diameter) correlated positively (r = 0.25, P < 0.01) with pH₂₄. Age-related effects on tenderness were small in comparison with pH₂₄ effects. CIELab colorimetric values were typical of game meat and venison (L^* < 40, high a^* and low b^* values). It was noted that pH₂₄ correlated negatively (r = −0.51, P < 0.001) and positively (r = 0.33, P < 0.001) with the hue-angle and the chroma value of colour, respectively. Springbok originating from Caledon had a significantly (P < 0.05) higher a^* value, indicating meat to be more red with higher colour saturation.     

Ultrafiltration fouling of amylose solution: Behavior, characterization and mechanism

Applications of ultrafiltration membrane often deal with feed streams containing amylose starch. This paper describes a detailed investigation of amylose fouling during ultrafiltration. Commercial membranes made of polysulfone and fluoro polymer were used. Both adsorptive and ultrafiltration fouling were investigated. Experiments using different membrane characteristics, feed concentrations and trans-membrane pressures were carried out. The resulting fouling was characterized by water flux and contact angle measurements and was visualized by scanning electron microscopy (SEM). The results suggest that solute adsorption has occurred as noticed by significant water flux reductions as well as changes in membrane characteristics. Further, both reversible and irreversible fouling have occurred during ultrafiltration with irreversible fouling was more dominant. Apparently, cake layer formation initiated by either adsorption due to hydrophobic–hydrophobic interactions or pore blocking is the dominant fouling mechanism. However, pore narrowing instead of pore blocking was also observed for the membrane having large and relative uniform pore structure or for the ultrafiltration using low trans-membrane pressure or low solute concentration. Membrane autopsy using SEM confirmed the formation of solute layer on the membrane surface.     

Inactivation of Enterobacter sakazakii by pulsed electric field in buffered peptone water and infant formula milk

The effect of high-intensity pulsed electric field (PEF) treatment on the survival of Enterobacter sakazakii suspended in buffered peptone water (BPW) and powdered infant formula milk (IFM) was evaluated. Reference medium and IFM samples were treated with PEF. Electric field intensity and treatment time were varied from 10 to 40 kV cm⁻¹ and from 60 to 3895 μs, respectively. Samples of buffered peptone water (3 g L⁻¹) and IFM were inoculated with E. sakazakii (CECT 858) (10⁹ cfu mL⁻¹) and then treated with PEF. The inactivation data were adjusted to the Weibull frequency distribution function and Bigelow model, and constants were calculated for both substrates. A maximum 2.7 log (cfu mL⁻¹) reduction was achieved in BPW after exposure of E. sakazakii to PEF for 360 μs (2.5 μs pulse width) at 40 kV cm⁻¹. In IFM, exposure of E. sakazakii to PEF, with the same conditions, led to a 1.2 log (cfu mL⁻¹) reduction. The greater the field strength and treatment time, the greater the inactivation achieved in both substrates. Even though further research will be necessary, according to the results, there are good prospects for the use of PEF in hospitals to achieve safe reconstituted infant formula before storage at refrigerated temperatures.     

Effect of modified atmospheres on microbiological, color and sensory properties of refrigerated pork

Pork loin samples were stored (4 °C) in nylon polyethylene plastic bags using different modified atmospheres packaging (MAP): vacuum, 100% CO₂ 99% CO₂ + 1% CO, 100% O₂ or 100% CO followed by vacuum. Throughout the storage period Pseudomonas growth was limited in loins packaged in all MAPs evaluated, except for 100% O₂. Psychrotrophs reached 10⁷ CFU g⁻¹ after 20 days of storage except for the loin samples in 100% O₂ MAP that present count above 10⁸ CFU g⁻¹. The 1% CO/99% CO₂ atmosphere was best for preserving the desirable pork loin color and the L* and a* values remained similar to the fresh meat values using this MAP. Pork loins in 99% CO₂/1% CO MAP obtained the highest consumer acceptance scores after 24 h of storage. These samples and those treated with CO and then vacuum packaged received the greatest acceptance scores even after 20 days of storage.     

A precise method to measure the total fat content of spreadable fats

A simple gravimetric solvent-extraction method was developed to determine the total fat content of a wide range of spreadable fats having fat contents in the range 23–82 g 100 g⁻¹. Operating parameters affecting the yield of lipid were optimised. The available evidence indicated that full recovery of mono- and diglycerides and sterols was obtained. The method was compared with the Schmid–Bondzynski–Ratzlaff (SBR) method, which was shown to have a much poorer repeatability and to co-extract non-lipid matter. Precision estimates obtained from a pilot collaborative study, involving six laboratories and 10 different spreadable fats, were 0.27 g 100 g⁻¹ and 0.44 g 100 g⁻¹ for repeatability (2.83s_r) and reproducibility (2.83s_R) respectively. These estimates were constant over the fat range tested and thus did not depend on the composition of the products. The relative repeatability standard deviations (RSD_r) and the relative reproducibility standard deviations (RSD_R) for total fat were very low with ranges of 0.10–0.32% and 0.15–0.95%, respectively. The method has fewer health and safety risks than the Röse Gottlieb and SBR methods and is deemed sufficiently precise to be used for checking the fat content of spreadable fats against legislative specifications.     

Effects of supercritical carbon dioxide extraction conditions on yields and antioxidant activity of Chlorella pyrenoidosa extracts

Yields and antioxidant activity of Chlorella pyrenoidosa extracts obtained by supercritical carbon dioxide extraction through an orthogonal experiment (L₁₆(4⁵)) were investigated to get the best extraction conditions. The results showed that extraction pressure, temperature and modifier were the main three variables that influenced the yields of extracts. The highest yield was obtained at 32 °C, 40 MPa, 20 L h⁻¹ with dosage of modifier 1 mL ethanol g⁻¹ sample for 3 h. Moreover, increasing pressure and concentrations of modifier led to the increase of extraction yields and antioxidant activity. DPPH radical scavenging method showed that almost all the extracts had significantly higher antiradical activities varying from 29.67 ± 0.29% to 54.16 ± 4.49% comparing to -tocopherol, Trolox, and BHT as references except extracts at 32 °C, 35 MPa and 15 L h⁻¹ without modifier for 1.5 h. These results indicate that supercritical extraction is a promising alternative process for recovering compounds of high antioxidant activity from C. pyrenoidosa.     

The effect of ultrasound waves on the efficiency of membrane clarification of pomegranate juice

Pomegranate juice has a turbid appearance, which poses difficulties in its concentration process. Membrane clarification can be used to clarify pomegranate juice; however, membrane fouling reduces the permeate flux, limiting its effectiveness. Ultrasound at 30 kHz was used to reduce membrane fouling. Results were compared with the data obtained for membrane clarification without ultrasonic treatment at the same temperature. Results showed that permeate flux increased with ultrasonic treatment. Evaluation of different membrane fouling characteristics showed that the total membrane resistance fell due to the reduction in irreversible fouling and cake resistance. However, ultrasound did not affect the thick caking produced in membrane processing at low feed‐flow rates. Evaluation of the physicochemical properties of pomegranate juice showed that ultrasound can decrease antioxidant activity due to the reduction in total anthocyanin content. Also, total soluble solid content and acidity of pomegranate juice changed with ultrasonic treatment.     

Influence of various preservatives on the quality of minced beef under modified atmosphere at chilled storage

The effect of preservatives on microbial quality, pH, drip-loss, roasting-loss, colour, and sensorial properties of modified atmosphere packaged (70% O₂ and 30% CO₂) minced beef (M. semimembranosus) stored at (2 ± 0.5 °C) for 12 days was investigated. Beef cubes (approx. 20 × 20 × 20 mm size) were immersed in solutions of 2% and 5% lactic acid, 2% lactic acid combined with 0.5% sodium ascorbate, 20% potassium lactate and 20% potassium sorbate before mincing. Addition of lactic acid was associated with pH drop, which increased drip-loss and roasting-loss. Application of all additives inhibited aerobic micro-organisms (10³–10⁴ CFU g⁻¹ on day 12) compared to reference sample (9 × 10⁵ CFU g⁻¹ on day 12). Lactic acid discoloured samples, while sodium ascorbate seemed to improve colour stability. Despite good visual colour characteristics, potassium sorbate treated samples were organoleptically unacceptable with massive off-flavour.     

Study of some factors affecting water absorption by amaranth grain during soaking

Water absorption by amaranth grain in plain water was determined at 30, 40, 50 and 60 °C by recording the weight increase in grain with respect to time. Water absorption kinetics at these temperatures was described by the Fick’s second law solution for diffusion out of sphere. Effective diffusion coefficients varied between 2.63 and 8.25 × 10⁻¹² m²/s for the range investigated. The activation energy for diffusion obtained was 32.1 kJ mol⁻¹. The rates of absorption in SO₂ aqueous solution (0.01%, 0.02% and 0.03%, v/v) were slightly higher than in plain water at 40 and 60 °C. However, the increase in SO₂ concentration did not seem to increase significantly water absorption. Amaranth grain soaked in 0.02% (v/v) SO₂ aqueous solution and variable lactic acid concentrations (0.0025% and 0.0050%, v/v) was performed at 40 °C. Absorption rates for lactic acid concentrations were ≈9.1% higher than those steeped only in SO₂ aqueous solution; lactic acid concentration had no effect on the absorption rate. The amount of total solids leached in sulfur dioxide solution with lactic acid (200 ppm SO₂ + 0.005% lactic acid) was the highest when compared with the other steeping media investigated.     

Enthalpy-Entropy compensation in food vapor adsorption

Enthalpy-entropy compensation was analysed for sorption isotherms of potatoes, macadamia nuts, apricots, figs, currants, prunes and raisins. Plots of (ΔH_dif)_T vs (ΔS_dif)_T for potatoes and macadamia nuts presented two isokinetic temperatures: T_B1 = 272.0 ± 57.7 K (− 1 °C) for potatoes, T_B1 = 265.0 ± 18.8 K (− 8 °C) for macadamia nuts and T_B2 = 382.5 ± 7.3 K (109.5 °C) for both products. The first isokinetic temperature (T_B1) appeared only at the upper portion of the temperature range tested (50, 60 and 70 °C for potatoes and 50 and 60 °C for macadamia nuts). The two isokinetic temperatures observed for potatoes and macadamia nuts suggested that during the initial stages at low a_w T_B1 is controlled by changes in the entropy of water, whereas the second isokinetic temperature (T_B2) is considered to be enthalpy-controlled. Dried fruits presented only one isokinetic curve T_B = 315.7 ± 3.5 K (42.7 °C), for raisins, currants and figs (75.2–82.3% d.b. sugars) and T_B = 317.7 ± 4.6 K (44.7 °C) for prunes and apricots (51.5–54.5% d.b. sugars), indicating an enthalpy-controlled adsorption process for the whole range of moisture contents covered.     

Effects of ultrafiltration of whole milk on some properties of spray-dried milk powders

The objective was to produce spray-dried milk powders for assessment subsequently in chocolate. Milks were ultrafiltered to increase their protein content (3.08–5.33 g 100 g⁻¹), concentrated to different solids levels (42.8–52.3 g 100 g⁻¹) and spray-dried to produce powders (26–59 g 100 g⁻¹ fat). The relationships between the milk protein content, concentrate viscosity and some powder properties were quantified. The free-fat content of the powders increased linearly to 74 g 100 g⁻¹ fat with milk protein content for 26 and 40 g 100 g⁻¹ fat powders. The particle size and moisture content of the powders increased linearly with concentrate viscosity for 26 g 100 g⁻¹ fat powders. Differences between the control and ultrafiltration-treated milk powders were explained. The free-fat content and the particle size increased with the fat content of the control powders. The vacuole volume of the powders was inversely more related to the free-fat content than to the fat content of the control powders.     

Drip loss of case-ready meat and of premium cuts and their associations with earlier measured sample drip loss, meat quality and carcass traits in pigs

Drip loss of 374 samples taken from porcine M. longissimus dorsi and M. semimembranosus was measured by using the “bag method” (BM), EZ-DripLoss (EZ-DL) from premium cuts (PC) and in retail tray (case-ready meat; CRM). This provided a comparison between these methods and their relationships to other meat quality and carcass traits. Samples were prepared at 24 h post-mortem (pm) and were measured 24 and 48 h after preparation (at 48 and 72 h pm) using the BM and after 48 h (at 72 h pm) with the EZ-DL and PC. Drip loss of meat kept in retail trays was measured after 7 days (CRM₇) and daily within a week (CRM_1–7). Average drip loss was 1.80% and 3.10% using the BM after 24 and 48 h, respectively. EZ-DL and CRM₇ showed higher drip losses of 4.71% and 4.00%. Daily loss of CRM_1–7 showed a concavely shaped curve and increased from 1.57% to 5.64% after 7 days. High correlations were obtained between drip loss of CRM₇ and BM (r = 0.88) or the EZ-DL (r = 0.91). The development of drip loss in case-ready meat fitted by linear-quadratic regression (y = 0.439 + 1.245x − 0.072x²) showed that high drip loss measured earlier by bag and EZ-DripLoss methods was highly associated with a high intercept (r = 0.63–0.72), a high linear increase (r = 0.77–0.81), but larger decrease in increments (r = −0.82 to −0.86) during weekly stored meat in retail trays as supplied at consumer level. Because the positive linear regression coefficient was substantially higher than the negative quadratic regression coefficient, the development of drip loss is mainly dependent on the initial drip loss. Therefore, animals with high drip loss within 72 h post-mortem also showed undesirable high drip loss curves over the entire retail period. Relationships between drip loss and other meat quality traits were similar for BM, EZ-DL and CRM₇. Of these the correlation between pH₂₄ and drip loss was highest with r = −0.54, −0.49 and −0.47 for BM, EZ-DL and CRMH₇, respectively. Interestingly, a correlation of r = −0.35 between blood pH value and CRML₇ was obtained. Carcass traits such as loin, ham, shoulder, belly weight or loin eye area showed only marginal correlations to drip loss. In conclusion, EZ-DL was the most appropriate method to predict drip loss of case-ready meat in retail trays and its development during a 7 day storage period.     

Numerical simulation of solid–liquid food mixture in a high pressure processing unit using computational fluid dynamics

Temperature distribution, velocity and pressure profiles during high pressure compression (500 MPa) of liquid food (water) and solid–liquid food mixture (beef fat and water), within a three dimensional cylinder basket is simulated. The computations domain in both cases was performed for a cylinder with a diameter of 38 mm and height of 290 mm, which are the same dimensions of the high pressure unit “FOOD-LAB model S-FL-850-9-W” available at the University of Auckland, New Zealand. The governing equations for continuity, momentum and energy conservation are solved using a commercial computational fluid dynamics (CFD) package (PHOENICS), version 3.5, which is based on a finite volume method of solution. The simulation for liquid food only shows the effect of forced and free convection flow on the temperature distribution in the liquid at the early stages of compression. This is due to the difference between the velocity of the pumping fluid as it enters the cylinder inlet hole (10⁻²–10⁻³) m s⁻¹ and the velocity in the treatment chamber (10⁻⁸–10⁻⁹) m s⁻¹. The simulation for the solid–liquid mixture shows as well, the temperature distribution in the solid and liquid at different stages of compression. It shows that the solid pieces are more heated than the liquid, which is due to the difference in their compression heating coefficient. Validation of the computed temperature in both cases is found to be in an agreement with those measured experimentally and reported in the literature.