Functional properties of ultrasonically generated flaxseed oil-dairy emulsions

This study reports on the functional properties of 7% flaxseed oil/milk emulsion obtained by sonication (OM) using 20 kHz ultrasound (US) at 176 W for 1–8 min in two different delivery formulae, viz., ready-to-drink (RTD) and lactic acid gel. The RTD emulsions showed no change in viscosity after sonication for up to 8 min followed by storage up to a minimum of 9 days at 4 ± 2 °C. Similarly, the oxidative stability of the RTD emulsion was studied by measuring the conjugated diene hydroperoxides (CD). The CD was unaffected after 8 min of ultrasonic processing. The safety aspect of US processing was evaluated by measuring the formation of CD at different power levels. The functional properties of OM gels were evaluated by small and large scale deformation studies. The sonication process improved the gelation characteristics, viz., decreased gelation time, increased elastic nature, decreased syneresis and increased gel strength. The presence of finer sono-emulsified oil globules, stabilized by partially denatured whey proteins, contributed to the improvements in the gel structure in comparison to sonicated and unsonicated pasteurized homogenized skim milk (PHSM) gels. A sono-emulsification process of 5 min followed by gelation for about 11 min can produce gels of highest textural attibutes.     

Impact of ultrasound treatment on lipid oxidation of Cheddar cheese whey

Ultrasound (US) has been suggested for many whey processing applications. This study examined the effects of ultrasound treatment on the oxidation of lipids in Cheddar cheese whey. Freshly pasteurized whey (0.86 L) was ultrasonicated in a contained environment at the same range of frequencies and energies for 10 and 30 min at 37 °C. The US reactor used was characterized by measuring the generation of free radicals in deionized water at different frequencies (20–2000 kHz) and specific energies (8.0–390 kJ/kg). Polar lipid (PL), free and bound fatty acids and lipid oxidation derived compounds were identified and quantified before and after US processing using high performance liquid chromatography equipped with an evaporative light scattering detector (HPLC–ELSD), methylation followed by gas chromatography flame ionized detector (GC-FID) and solid phase micro-extraction gas chromatography mass spectrometry (SPME-GCMS), respectively. The highest concentration of hydroxyl radical formation in the sonicated whey was found between 400 and 1000 kHz. There were no changes in phospholipid composition after US processing at 20, 400, 1000 and 2000 kHz compared to non-sonicated samples. Lipid oxidation volatile compounds were detected in both non-sonicated and sonicated whey. Lipid oxidation was not promoted at any tested frequency or specific energy. Free fatty acid concentration was not affected by US treatment per se. Results revealed that US can be utilized in whey processing applications with no negative impact on whey lipid chemistry.     

Lipid oxidation volatiles absent in milk after selected ultrasound processing

Ultrasonic processing can suit a number of potential applications in the dairy industry. However, the impact of ultrasound treatment on milk stability during storage has not been fully explored under wider ranges of frequencies, specific energies and temperature applications. The effect of ultrasonication on lipid oxidation was investigated in various types of milk. Four batches of raw milk (up to 2 L) were sonicated at various frequencies (20, 400, 1000, 1600 and 2000 kHz), using different temperatures (4, 20, 45 and 63 °C), sonication times and ultrasound energy inputs up to 409 kJ/kg. Pasteurized skim milk was also sonicated at low and high frequency for comparison. In selected experiments, non-sonicated and sonicated samples were stored at 4 °C and were drawn periodically up to 14 days for SPME–GCMS analysis. The cavitational yield, characterized in all systems in water, was highest between 400 kHz and 1000 kHz. Volatile compounds from milk lipid oxidation were detected and exceeded their odor threshold values at 400 kHz and 1000 kHz at specific energies greater than 271 kJ/kg in raw milk. However, no oxidative volatile compounds were detected below 230 kJ/kg in batch systems at the tested frequencies under refrigerated conditions. Skim milk showed a lower energy threshold for oxidative volatile formation. The same oxidative volatiles were detected after various passes of milk through a 0.3 L flow cell enclosing a 20 kHz horn and operating above 90 kJ/kg. This study showed that lipid oxidation in milk can be controlled by decreasing the sonication time and the temperature in the system depending on the fat content in the sample among other factors.     

Physicochemical characterization of black seed oil-milk emulsions through ultrasonication

The ultrasonic formation of stable emulsions of a bioactive material, black seed oil, in skim milk was investigated. The incorporation of 7% of black seed oil in pasteurised homogenized skim milk (PHSM) using 20 kHz high intensity ultrasound was successfully achieved. The effect of sonication time and acoustic power on the emulsion stability was studied. A minimum process time of 8 min at an applied acoustic power of 100 W was sufficient to produce emulsion droplets stable for at least 8 days upon storage at 4 ± 2 °C, which was confirmed through creaming stability, particle size, rheology and color analysis. Partially denatured whey proteins may provide stability to the emulsion droplets and in addition to the cavitation effects of ultrasound are responsible for the production of smaller sized emulsion droplets.     

Sonication enhances polyphenolic compounds,sugars, carotenoids and mineral elements of apple juice

A study was initiated with the objective of evaluating the effects of sonication treatment on quality characteristics of apple juice such as polyphenolic compounds (chlorogenic acid, caffeic acid, catechin, epicatechin and phloridzin), sugars (fructose, glucose and sucrose), mineral elements (Na, K, Ca, P, Mg, Cu and Zn), total carotenoids, total anthocyanins, viscosity and electrical conductivity. The fresh apple juice samples were sonicated for 0, 30 and 60 min at 20 °C (frequency 25 kHz and amplitude 70%), respectively. As results, the contents of polyphenolic compounds and sugars significantly increased (P < 0.05) but the increases were more pronounced in juice samples sonicated for 30 min whereas, total carotenoids, mineral elements (Na, K and Ca) and viscosity significantly increased (P < 0.05) in samples treated for 60 min sonication. Losses of some mineral elements (P, Mg and Cu) also occurred. Total anthocyanins, Zn and electrical conductivity did not undergo any change in the sonicated samples. Findings of the present study suggest that sonication technique may be applied to improve phytonutrients present naturally in apple juice.     

Sonocrystallisation of lactose in concentrated whey

Whey concentrated to 32% lactose was sonicated at 30 °C in a non-contact approach at flow rates of up to 12 L/min. Applied energy density varied from 3 to 16 J/mL at a frequency of 20 kHz. Sonication of whey initiated the rapid formation of a large number of lactose crystals in response to acoustic cavitation which increased the rate of crystallisation. The rate of sonocrystallisation was greater than stirring for approximately 180 min but slowed down between 120 and 180 min as the metastable limit was reached. A second treatment with ultrasound at 120 min delivering an applied energy density of 4 J/mL stimulated further nuclei formation and the rate of crystallisation was maintained for >300 min. Yield on the other hand was limited by the solubility of lactose and could not be improved. The crystal size distribution was narrower than that with stirring and the overall crystal size was smaller.     

Effect of sonication on B cell development and immunomodulatory functions of Bursa of Fabricius

A study was initiated with the objective of evaluating the effects of sonication treatment on important quality parameters of extract of Bursa of Fabricius. Sonication of extract was done (frequency 20 kHz and various amplitude levels) at 0 °C for 10 min, 30 min, 50 min, respectively. As results, the yield of bursa peptides significantly increased (p < 0.05). Then we found sonicated bursa extract promoted the content of bursin and the CFU pre-B formation, exerted immunomodulatory function on antigen-specific immune responses in C57/BL6 mice immunized with inactivated Japanese encephalitis b virus (JEV) vaccine, including enhancing JEV-specific antibody and cytokine production, T-cell immunophenotyping and lymphocyte proliferation. Findings of the present study suggested the sonication treatment of Bursa of Fabricius could improve the yield as well as the quality of bursa peptides, indicating that sonication is effective in processing of bursa extract and could be a potential process for future immuno-pharmacological use.     

Effects of thermal treatment and sonication on quality attributes of Chokanan mango (Mangifera indica L.) juice

Ultrasonic treatment is an emerging food processing technology that has growing interest among health-conscious consumers. Freshly squeezed Chokanan mango juice was thermally treated (at 90 °C for 30 and 60 s) and sonicated (for 15, 30 and 60 min at 25 °C, 40 kHz frequency, 130 W) to compare the effect on microbial inactivation, physicochemical properties, antioxidant activities and other quality parameters. After sonication and thermal treatment, no significant changes occurred in pH, total soluble solids and titratable acidity. Sonication for 15 and 30 min showed significant improvement in selected quality parameters except color and ascorbic acid content, when compared to freshly squeezed juice (control). A significant increase in extractability of carotenoids (4–9%) and polyphenols (30–35%) was observed for juice subjected to ultrasonic treatment for 15 and 30 min, when compared to the control. In addition, enhancement of radical scavenging activity and reducing power was observed in all sonicated juice samples regardless of treatment time. Thermal and ultrasonic treatment exhibited significant reduction in microbial count of the juice. The results obtained support the use of sonication to improve the quality of Chokanan mango juice along with safety standard as an alternative to thermal treatment.     

Ultrasonic pretreatment of corn slurry for saccharification: A comparison of batch and continuous systems

The effects of ultrasound on corn slurry saccharification yield and particle size distribution was studied in both batch and continuous-flow ultrasonic systems operating at a frequency of 20 kHz. Ground corn slurry (28% w/v) was prepared and sonicated in batches at various amplitudes (192–320 μm_{peak-to-peak (p–p)}) for 20 or 40 s using a catenoidal horn. Continuous flow experiments were conducted by pumping corn slurry at various flow rates (10–28 l/min) through an ultrasonic reactor at constant amplitude of 12 μm_p–p. The reactor was equipped with a donut shaped horn. After ultrasonic treatment, commercial alpha- and gluco-amylases (STARGEN^TM 001) were added to the samples, and liquefaction and saccharification proceeded for 3 h. The sonicated samples were found to yield 2–3 times more reducing sugars than unsonicated controls. Although the continuous flow treatments released less reducing sugar compared to the batch systems, the continuous flow process was more energy efficient. The reduction of particle size due to sonication was approximately proportional to the dissipated ultrasonic energy regardless of the type of system used. Scanning electron microscopy (SEM) images were also used to observe the disruption of corn particles after sonication. Overall, the study suggests that both batch and continuous ultrasonication enhanced saccharification yields and reduced the particle size of corn slurry. However, due to the large volume involve in full scale processes, an ultrasonic continuous system is recommended.     

Ultrasound influence on the solubility of solid dispersions prepared for a poorly soluble drug

Solid dispersions have been successfully used to enhance the solubility of several poorly water soluble drugs. Solid dispersions are produced by melting hydrophilic carriers and mixing in the poorly water soluble drug. Supersaturation is obtained by quickly cooling the mixture until it solidifies, thereby entrapping the drug. The effects of using ultrasound to homogenize the molten carrier and drug mixture were studied. In particular, the increase in drug solubility for the resulting solid dispersions was analyzed. Piroxicam, which has very low water solubility, was used as a model drug. A full factorial design was used to analyze how sonication parameters affected the solubility and in vitro release of the drug. The results show that the use of ultrasound can significantly increase the solubility and dissolution rate of the piroxicam solid dispersion. Pure piroxicam presented a solubility of 13.3 μg/mL. A maximum fourfold increase in solubility, reaching 53.8 μg/mL, was observed for a solid dispersion sonicated at 19 kHz for 10 min and 475 W. The in vitro dissolution rate test showed the sonicated solid dispersion reached a maximum rate of 18%/min, a sixfold increase over the piroxicam rate of 2.9%/min. Further solid state characterization by thermal, X-ray diffraction and Fourier transform infrared analyses also showed that the sonication process, in the described conditions, did not adversely alter the drug or significantly change its polymorphic form. Ultrasound is therefore an interesting technique to homogenize drug/carrier mixtures with the objective of increasing the solubility of drugs with poor water solubility.     

Enhancement of artificial promoter activity by ultrasound-induced oxidative stress

We previously developed artificial promoters that were activated in response to X-ray irradiation. Sonication with 1.0 MHz ultrasound that causes intracellular oxidative stress was found to activate some of these promoters though to lesser degrees. The most sensitive one among these promoters showed intensity- and duration-dependent activations by sonication. In addition, its activation by sonication was attenuated when N-acetyl cysteine was present, suggesting the involvement of intracellular oxidative stress in the activation mechanism. Improved promoters for sensitivity to X-ray irradiation were also found more sensitive to sonication. The most improved one showed 6.0 fold enhancement after sonication with 1.0 MHz ultrasound at 1.0 W/cm² for 60 s. This enhancement was also attenuated with the presence of N-acetyl cysteine. When stably transfected HeLa cells with the most sensitive promoter were transplanted on to mice and sonicated, luciferase activity by the promoter increased to 1.35 fold in average though it was not statistically significant compared to control. Although gene regulation in vivo by sonication was not clear, this is the first report on artificially constructed promoters responsive to ultrasound.     

Ultrasound assisted hydration of navy beans (Phaseolus vulgaris)

The use of ultrasound to enhance the transport phenomena in food processes has been well recognised in recent times. The objective of this study was to evaluate the effect of sonication on hydration rate and pasting profile of navy beans. The hydration kinetics for control and ultrasound assisted soaking was mathematically described using mechanistic (Fickian diffusion) and empirical (Peleg’s equation, Weibull model and First Order equation) models. Ultrasound enhanced the rate of hydration which was evident from the plot of kinetic data and model parameters. The effective diffusivities for water transport without and with ultrasound application were estimated to be 1.36 × 10⁻¹⁰ m²/s and 2.19 × 10⁻¹⁰ m²/s respectively, considering Fickian diffusion. The Weibull model was concluded to best predict the hydration kinetics of navy beans in an ultrasonic field. Significant increase in peak viscosity of sonicated bean powder was observed compared to control.     

Ascorbic acid stability in fruit juices during thermosonication

Thermosonication is an emerging technology useful for inactivating microorganisms and enzymes in fruit juices. However, the effect of the ultrasound processing on the ascorbic acid content is not clear and the results reported in the literature are contradictory. In this work, the impact of sonication and thermosonication on the ascorbic acid content was first evaluated in model systems. Degassed model solutions at four different pH values (3–6) were processed with or without sonication for 60 min at two different conditions of temperature (25 and 55 °C). In all cases, the ascorbic acid was stable under the treatment. After that, two commercial deaerated fruit juices were processed with and without US at 55 °C. The ascorbic acid was also retained in these juices after the ultrasound processing under the most severe conditions studied. In conclusion, previous degassing/deaerating of fruit juices is recommended to prevent ascorbic acid degradation when thermosonication is applied.     

Ultrasonic destruction of pesticide contaminants in slurries

The use of high power ultrasound to destroy pesticide contaminants in sand slurries is reported. Small quantities of DDT, chlordane, atrazine, 2,4,5-T and endosulfan in solvent were added to washed, screened sand and deposited onto the sand by slow evaporation of the solvent. Fifty wt.% slurries for all five pesticides and 20 wt.% slurries of atrazine and 2,4,5-T were sonicated for periods up to 30 min and samples were withdrawn at various intervals and analysed to follow the kinetics of contaminant destruction. Seventy percent destruction of the contaminant was obtained for four of the 50 wt.% slurries with approximately 50% destruction of 2,4,5-T in 10 min of sonication whereas, in the 20 wt.% slurries of atrazine and 2,4,5-T, and 75% and 85% reduction, respectively, was obtained in 10 min. We postulate that better stirring of the slurry will improve these rates of contaminant destruction.     

Rapid growth of hydroxyapatite nanoparticles using ultrasonic irradiation

A rapid, environmental friendly and low-cost method to prepare hydroxyapatite nanoparticles is proposed. In this method, hydroxyapatite is produced in a sonicated pseudo-body solution. The sonication time was found effective in the formation of the crystalline phase of nanoparticles. In our experimental condition, 15 min sonication resulted in the most pure hydroxyapatite phase. Also it was shown that growth temperature is a crucial factor and hydroxyapatite crystallizes only at 37 °C. The particles formed by sonication were generally smaller and more spherical than those obtained without sonication. Sonication increased the hydroxyapatite crystal growth rate up to 5.5 times compared to non-sonication condition. The comparison between the specific surface area of hydroxyapatite nanoparticles obtained by sonication and without sonication demonstrated that sonication increased the specific surface area from 63 m²/g to 107 m²/g and decreased the size of nanoparticles from 30 nm to 18 nm. Analysis on the pore structure demonstrated that the fractal structures obtained with and without sonication were considerably different.     

The effect of low frequency ultrasound on the production and properties of nanocrystalline cellulose suspensions and films

Suspension of nanocrystalline cellulose (NCC) produced from bleached cotton by controlled sulphuric acid hydrolysis was treated with low frequency ultrasound at 20 kHz and 60% amplitude for 0, 1, 2, 5 and 10 min and the effects of sonication on the properties of both the cellulose nanocrystals and their aqueous suspensions were investigated. Furthermore, a series of nanocellulose films were manufactured from the suspensions that were sonicated for different periods of time and tested. Laser diffraction analysis and transmission electron microscopy proved that sonication not only disintegrated the large NCC aggregates (D_v50 14.7 μm) to individual nanowhiskers with an average length and width of 171 ± 57 and 17 ± 4 nm, respectively, but also degraded the nanocrystals and yielded shorter and thinner particles (118 ± 45 and 13 ± 3 nm, respectively) at 10-min sonication. The ultrasound-assisted disintegration to nano-sized cellulose whiskers decreased the optical haze of suspensions from 98.4% to 52.8% with increasing time from 0 to 10 min, respectively. Sonication of the suspensions significantly contributed to the preparation of films with low haze (high transparency) and excellent tensile properties. With the increasing duration of sonication, the haze decreased and the tensile strength rose gradually. Irrespectively of sonication, however, all films had an outstanding oxygen transmission rate in a range of 5.5–6.9 cm³/m² day, and a poor thermal stability.     

Dual frequency cavitation event sensor with iodide dosimeter

The inertial cavitation activity depends on the sonication parameters. The purpose of this work is development of dual frequency inertial cavitation meter for therapeutic applications of ultrasound waves. In this study, the chemical effects of sonication parameters in dual frequency sonication (40 kHz and 1 MHz) were investigated in the progressive wave mode using iodide dosimetry. For this purpose, efficacy of different exposure parameters such as intensity, sonication duration, sonication mode, duty factor and net ultrasound energy on the inertial cavitation activity have been studied. To quantify cavitational effects, the KI dosimeter solution was sonicated and its absorbance at a wavelength of 350 nm was measured. The absorbance values in continuous sonication mode was significantly higher than the absorbance corresponding to the pulsed mode having duty factors of 20–80% (p < 0.05). Among different combination modes (1 MHz_100% + 40 kHz_100%, 1 MHz_100% + 40 kHz_80%, 1 MHz_80% + 40 kHz_100%, 1 MHz_80% + 40 kHz_80%), the continuous mode for dual frequency sonication is more effective than other combinations (p < 0.05). The absorbance for this combined dual frequency mode was about 1.8 times higher than that obtained from the algebraic summation of single frequency sonications. It is believed that the optimization of dual frequency sonication parameters at low-level intensity (<3 W/cm²) by optically assisted cavitation event sensor can be useful for ultrasonic treatments.     

Effect of sonication on different quality parameters of Pinus massoniana pollen

A study was initiated with the objective of evaluating the effects of sonication treatment on important quality parameters of extract of Pinus massoniana pollen. Sonication of extract was done (frequency 20 kHz and various amplitude levels) for 10, 30, 50 min, respectively. As results, total polysaccharide, phenolics and flavonoids significantly increased (P < 0.05). And sonicated P. massoniana pollen displays strong immuno-stimulating activity by increasing proliferations of splenic lymphocytes and subsets of CD4+ T cells (CD3+CD4+), CD8 T cells (CD3+CD8+), and increased Ig secretion. Sonicated P. massoniana pollen also showed anti-tumor function by inhibition of tumor cell proliferation, inhibition of ROS production, up-regulation of GSH/GSSG ration, up-regulating the gene expression of P53, Bax and down-regulating the gene expression of Bcl-2. Findings of the present study suggested the sonication treatment of P. massoniana pollen could improve the quality and bioactivity of P. massoniana pollen, indicating that sonication is effective in processing of pollen and could be a potential process in tumor prevention and treatment.     

Effect of melt-processing and ultrasonic treatment on physical properties of high-amylose maize starch

High-amylose maize starch (Hylon VII) was submitted to melt-processing in an internal mixer at 100 °C and 40 rpm for 8 min. Glycerol was used as a plasticiser at different polymer/glycerol ratios. Torque and temperature curves were obtained. After glycerol extraction with ethyl alcohol, the samples were dispersed at 5 g/L, and treated by ultrasound radiation at the same conditions for 30 min. Samples were characterised by ¹H NMR spectrometry, viscosity measurements, and X-ray diffractometry. The results revealed that both glycerol and water had an important role on the crystallinity properties of the resulting products. Melt-processed and sonicated samples showed similar ¹H NMR spectra. Ultrasound treatment caused a significant reduction in intrinsic viscosity for the sample previously processed with the highest glycerol content, probably because of its higher solubility in water.