Application Of Ultrasonication Research Articles

Ultrasound treatment improved the physicochemical properties of pea protein with pectin ink used for 3D printing

Pectin, as a gelling agent enhancer, is capable of augmenting the strength of plant protein gels; however, their direct blending often results in insignificant crosslinking efficiency. The application of ultrasonication has been found to effectively promote crosslinking interactions between pectin and plant proteins. This study primarily probes into the physicochemical impacts on the pea protein system instigated by ultrasonicated apple pectin (AP), citrus pectin (CP), and high methoxyl pectin (HM) variances. It has been revealed that the incorporation of pectin, subsequent to ultrasonication, ameliorates the textural and rheological traits of the pea protein matrix. Nevertheless, the introduction of high methoxyl pectin excessively enhances these identical properties, rendering it unsuitable for use in food development and three-dimensional (3D) printing technologies. Under an ultrasound power setting of 390 W, the citrus pectin variant outperforms other variants with its superior hardness, elasticity, and viscoelasticity, thereby significantly bolstering the self-supporting capability and malleability of the pea protein system for potential utilization in 3D printing applications. In conclusion, the ultrasonically treated pectin-pea protein amalgam optimizes the physicochemical attributes of the pea protein system, contributing to the stability enhancement of 3D printed products.

Ultrasound assisted phytochemical extraction of red cabbage by using deep eutectic solvent: Modelling using ANFIS and optimization by genetic algorithms

The present investigation studied the effect of process parameters on the extraction of phytochemicals from red cabbage by the application of ultrasonication and temperature. The solvent selected for the study was deep eutectic solvent (DES) prepared by choline chloride and citric acid. The ultrasound assisted extraction process was modeled using adaptive neuro-fuzzy inference system (ANFIS) algorithm and integrated with the genetic algorithm for optimization purposes. The independent variables that influenced the responses (total phenolic content, antioxidant activity, total anthocyanin activity, and total flavonoid content) were ultrasonication power, temperature, molar ratio of DES, and water content of DES. Each ANFIS model was formed by the training of three Gaussian-type membership functions (MF) for each input, trained by a hybrid algorithm with 500 epochs and linear type MF for output MF. The ANFIS model predicted each response close to the experimental data which is evident by the statistical parameters (R2>0.953 and RMSE <1.165). The integrated hybrid ANFIS-GA algorithm predicted the optimized condition for the process parameters of ultrasound assisted extraction of phytochemicals from red cabbage was found to be 252.114 W for ultrasonication power, 52.715 °C of temperature, 2.0677:1 of molar ratio of DES and 25.947 % of water content in DES solvent with maximum extraction content of responses, with fitness value 3.352. The relative deviation between the experimental and ANFIS predicted values for total phenolic content, antioxidant activity, total anthocyanin activity, and total flavonoid content was found to be 1.849 %, 3.495 %, 2.801 %, and 4.661 % respectively.

Recent Developments in the Application of Ultrasonication in Pre-Treatment of Municipal Sewage Sludge

Recent Developments in the Application of Ultrasonication in Pre-Treatment of Municipal Sewage Sludge

Cost estimation for application of ultrasonication–ozonation hybrid process in remediation of PAH-contaminated soil

Cost estimation for application of ultrasonication–ozonation hybrid process in remediation of PAH-contaminated soil

Effect of ultrasonic on the chemical composition of stirred yoghurt supplemented with orange peel powder

Heat treatments in dairy processing exert undesirable effects on the final product. Alternatively, a high-intensity ultrasonic technique was applied to process stirred yoghurt supplemented with orange peel powder (OPP). For this reason, OPP was added to the fresh milk at concentrations of 0.0, 1, and 2%, and then the mixture was subjected to ultrasound waves (24 kHz at 45 ± 2 °C for 30 min) before being incubated with the starter culture w/v%. Analysis of fresh and stored samples (7 and 14 days) showed that ultrasonic-treated milk (UTM) had a longer fermentation time than the heat-treated sample (HTM). No significant differences in total solid content, protein, ash, and volatile fatty acids were observed between UTM and HTM samples, while slight differences due to the addition of OPP were detected. Treating milk with ultrasound waves improved the processed yogurt’s apparent viscosity and water-holding capacity; however, adding OPP resulted in minor reverse effects. Total flavonoid and phenolic contents and antioxidant activity increased by adding OPP and were significantly higher in yoghurt made from UTM than in HTM. Overall, the application of ultrasonication in processing OPP- supplemented yoghurt resulted in better chemical and physical properties and maintained bioactive antioxidant components compared to yogurt manufactured from HTM.

Application of Microwave and Ultrasonication for Anthocyanin Extraction Process from Garcinia indica Choisy Fruit Waste and Assessment of Antioxidant Activity using Caenorhabditis elegans Model

Abstract: Garcinia indica (also known as kokum) is a small evergreen tree that has been used in a variety of culinary, industrial, and pharmacological products, as well as fruit juices and food. In the present study, the antioxidant capacity of anthocyanin extracted from Garcinia indica fruit waste was assessed using DPPH, ABTS assay, and a Caenorhabditis elegans infection model. The independent variables, such as temperature, solvent concentration, microwave exposure, and exposure to ultrasonication were integrated as independent variables in a five-level central composite design using response surface methodology. Based on statistical analysis, the generated models were successfully utilised to analyse the experimental data and determine the best extraction conditions. The rescue effect of anthocyanin was further studied using a paralysis and killing assay in a C. elegans infection model. The extraction yield was 21.0 mg/g under these conditions, with antioxidant activity of 9.9 μg/ml by ABTS assay and 6.6 μg/ml by DPPH assay, respectively. Furthermore, as compared to ethanol leaching extraction, this experimental design increased anthocyanin yield by more than 15 fold. The treatment of anthocyanin with C. elegans from E. coli and Pseudomonas aeruginosa PAO1 infection resulted in a significantly longer lifetime. Garcinia indica fruit waste extracts high in anthocyanins might be employed as natural food colorants and antioxidant additives in food products.

Selection of Mechanical Fragmentation Methods Based on Enzyme-Free Preparation of Decellularized Adipose-Derived Matrix.

The decellularized adipose-derived matrix (DAM) has emerged as a promising biomaterial for inducing adipose tissue regeneration. Various methods have been employed to produce DAM, among which the enzyme-free method is a relatively recent preparation technique. The mechanical fragmentation step plays a crucial role in determining the efficacy of the enzyme-free preparation. The adipose tissue underwent fragmentation through the application of ultrasonication, homogenization, and freeze ball milling. This study compared the central temperature of the mixture immediately following crushing, the quantity of oil obtained after centrifugation, and the thickness of the middle layer. Fluorescence staining was utilized to compare the residual cell activity of the broken fat in the middle layer, while electron microscopy was employed to assess the integrity and properties of the adipocytes among the three methods. The primary products obtained through the three methods were subsequently subjected to processing using the enzyme-free method DAM. The assessment of degreasing and denucleation of DAM was conducted through HE staining, oil red staining, and determination of DNA residues. Subsequently, the ultrasonication-DAM (U-DAM) and homogenation-DAM (H-DAM) were implanted bilaterally on the back of immunocompromised mice, and a comparative analysis of their adipogenic and angiogenic effects in vivo was performed. Oil discharge following ultrasonication and homogenization was significantly higher compared to that observed after freeze ball milling (p < 0.001), despite the latter exhibiting the lowest center temperature (p < 0.001). The middle layer was found to be thinnest after ultrasonication (p < 0.001), and most of the remaining cells were observed to be dead following fragmentation. Except for DAM obtained through freeze ball milling, DAM obtained through ultrasonication and homogenization could be completely denucleated and degreased. In the in vivo experiment, the first adipocytes were observed in U-DAM as early as 1 week after implantation, but not in H-DAM. After 8 weeks, a significant number of adipocytes were regenerated in both groups, but the U-DAM group demonstrated a more efficient adipose regeneration than in H-DAM (p = 0.0057). Ultrasonication and homogenization are effective mechanical fragmentation methods for breaking down adipocytes at the initial stage, enabling the production of DAM through an enzyme-free method that facilitates successful regeneration of adipose tissues in vivo. Furthermore, the enzyme-free method, which is based on the ultrasonication pre-fragmentation approach, exhibits superior performance in terms of denucleation, degreasing, and the removal of non-adipocyte matrix components, thereby resulting in the highest in vivo adipogenic induction efficiency.

Application of ultrasonication and PEGylation as green extraction technology for yield intensification of diallyl thiosulfinate (allicin)

The numerous advantages of bioactive phytochemicals like Diallyl thiosulfinate (DATS) or allicin on human health have attracted scientific inventions and innovations in the latest years for the application in formulating dietary supplements, food products and medicines. In order to maximize the extraction of the phytodrug DATS from Allium sativum, an indigenous approach was devised that relies on the hybrid application of ultrasonication and self-aggregation property of nonionic polymers. Under the optimal conditions of several process parameters (including solvent to garlic biomass ratio, ultrasonic amplitude, ultrasonic duty cycle, ultrasonication time), optimal efficiency of DATS extraction was achieved (3.67 mg/g of garlic biomass). From the two-way ANOVA analysis, ultrasound amplitude was found most significant parameter. Additionally, this proposed approach was able to enhance ∼2.67 fold yield of DATS with significantly lower electric power consumption than the conventional technique. Moreover, polyethylene glycol based pH responsive self-assembly carrier system was prepared which helped to maintain a 94% concentration of DATS for around 30 days and reduced the concentration loss of DATS because of molecular degradation. This hybrid extraction-stabilization method can be beneficial for the industrial application of DATS extraction because its bioactivity was well preserved as observed from the in vitro antibacterial experiment.

Structural Characterization and Peroxidation Stability of Palm Oil-Based Oleogel Made with Different Concentrations of Carnauba Wax and Processed with Ultrasonication.

The effect of ultrasonication (25 kHz for 10 min) on physical, thermal, and structural properties and storage stability of palm oil-based oleogels prepared using different concentrations of carnauba wax (CW) (5% or 10%) were investigated and compared with oleogels prepared with a homogenizer (2000 rpm for 10 min). Overall, this study found that applying an ultrasonication process with higher CW concentration (10%) effectively improved the properties and stability of palm oil-based oleogel (p &lt; 0.05). Oleogels processed with ultrasonication had higher lightness (L*), higher yellowness (b*), and lower redness (a*) than those processed with homogenizer (p &lt; 0.05), irrespective of CW concentrations. However, a higher CW concentration (10%) increased the textural properties of oleogels such as hardness, stickiness, and tackiness as compared to oleogels with a lower CW concentration (5%) (p &lt; 0.05). Thermal properties including melting onset temperature, melting peak temperature, and melting enthalpy were found to be significantly higher in ultrasonication-processed oleogels with high CW concentration (p &lt; 0.05). Furthermore, the microscopic examination of the oleogels exhibited a strong gel network when prepared using a high concentration of CW and processed with ultrasonication. Fourier Transform Infrared (FTIR) spectra of oleogels revealed that strong intra- and intermolecular interactions were formed by hydrogen bonding between CW and palm oil. X-ray diffraction (XRD) showed a smooth and fine structural network of oleogels and proved that ultrasonication increased the structural properties of oleogel. Moreover, oil loss and peroxide value of oleogels were increased during 90 days of storage (p &lt; 0.05). However, oleogels processed with the ultrasonication had reduced oil loss and increased peroxidation stability during storage (p &lt; 0.05). Overall, this study showed that application of ultrasonication with a higher CW concentration could improve properties and storage stability of palm oil-based oleogel.

Ultrasound‐assisted extraction of mango seed kernel butter and assessment of its physicochemical, thermal, and structural properties

AbstractMango is an important tropical fruit with worldwide consumption and acceptance; however, the production of a large volume of waste in the form of mango seed kernels after the processing of mango has been a menace to food processing industries. Extraction of mango seed kernel butter from mango seed kernel can be an effective solution for the valorization of these by‐products. Among all the green techniques tested in the present studies, ultrasound‐assisted extraction gave the highest yield of mango seed kernel butter (11%) at 25°C, 1:20 solid–liquid ratio, 30% amplitude after a treatment time of 10 min. Physicochemical, structural, and thermal profiles of the extracted mango seed kernel butter revealed a comparatively superior quality of fat obtained using the ultrasonication technique as compared to the conventional method. Peroxide value, acid value, and antioxidant activity of mango seed kernel butter obtained using ultrasonication were found to be 2.8 meq/kg, 3.81 mg KOH/g, and 30.7%, respectively. Mango seed kernel butter, being a natural antioxidant, can serve as a promising substitute to edible oils and as a functional food ingredient in bakery and confectionery.Practical applicationsValorization of mango seed kernels for the extraction of mango seed kernel butter offers a sustainable and economical solution for the effective management of by‐products generated after mango processing. The application of ultrasonication can prove to be an effective green technique for the extraction of mango seed kernel butter with a higher yield obtained with lesser time and solvent consumption than conventional techniques. The ultrasonically extracted mango seed kernel butter exhibited better physicochemical and structural attributes than the conventional method without causing any negative impact on the nutritional profile of the obtained fat. The extracted mango seed kernel butter can be utilized as a functional food ingredient in applications of bakery and confectionary industries.

Impact of ultrasound and medium condition on production of selenium-enriched yeast

BackgroundUltrasonication was used to stimulate the growth and selenium (Se) biotransformation in Saccharomyces cerevisiae. An optimization study for maximal Se accumulation in S. cerevisiae was conducted using the Plackett–Burman screening method and response surface methodology (RSM) for optimization of conditions. The variables influencing Se biotransformation by yeast, including duration and power of ultrasound, inoculum treatment with ultrasound, duty cycle, growth phase, time, shaking rate, inorganic salt concentration (Se, Zn, Mg, and K), and nitrogen and carbon sources as well as their concentrations were screened using the Plackett–Burman design. ResultsThe main variables were carbon and Se concentration as well as ultrasound power and duty cycle. The lack of fit was insignificant (P > 0.01). The optimum condition for Se accumulation was obtained at Se concentration of 60 µg/ml, carbon source brix of 15, ultrasound of 90 W/L, and duty cycle of 40%. ConclusionsThe results showed that optimization of parameters and application of ultrasonication lead to a successful enhancement (2.78-fold) in the accumulation of selenium by S. cerevisiae. Such enriched yeast can be utilized in bread for increasing consumption of Se in the diet of patients with Se deficiency.How to cite: Alijan S, Hosseini M, Esmaeili S, et al. Impact of ultrasound and medium condition on production of selenium-enriched yeast. Electron J Biotechnol 2022;60. https://doi.org/10.1016/j.ejbt.2022.09.004.

Enzymatic bioactive peptides from sonicated whey proteins of camel milk: Impacts of nanopeptides on structural properties, antioxidant activity and inhibitory activity of alpha‐amylase and ACE

This study was carried out to investigate the biological properties of bioactive peptides derived from digestive enzymatic hydrolysis for nanoscaled protein particles from camel whey proteins. The hydrolysates were tested for aromatic content, antioxidant activity, α‐amylase inhibitory and angiotensin‐converting enzyme (ACE) activities. The sonicated camel whey protein particles showed sizes less than 100 nm and were distributed in a 75% volume with a relatively stable −23.1 mV zeta potential value. Sonication enhanced the total aromatic ring content in the hydrolysates generated by combined trypsin and chymotrypsin treatment. A decrease in antioxidant activity was shown following trypsin and chymotrypsin hydrolysis that was inhibited by whey protein sonication. Pepsin hydrolysis improved aromatic content, ACE and α‐amylase inhibitory activities, and antioxidant activity. An increase in antioxidant activity of the pepsin‐derived hydrolysates was seen with sonicated whey proteins. Overall, the findings demonstrate the utility of the application of enzymatic hydrolysis and/or ultrasonication of camel whey proteins to enhance their antioxidant, anti‐hypertensive and anti‐diabetic properties.

Ultrasonication for production of nanoliposomes with encapsulated soy protein concentrate hydrolysate: Process optimization, vesicle characteristics and in vitro digestion.

This study presents the state-of-art research about the assembly of soy proteins in nanocarriers, liposomes, and its design includes different physicochemical strategies and approaches: two-step enzymatic hydrolysis of soy concentrate, hydrolysate encapsulation by using phospholipids and cholesterol, and application of ultrasonication. Achieved results revealed that ultrasonication, together with cholesterol addition into phospholipid layers, improved the stability of nanoliposomes, and a maximum EE value of 60.5% was obtained. Average size of peptide-loaded nanoliposomes was found to be from 191.1 to 286.7nm, with a ζ potential of -25.5 to -34.6mV, and a polydispersity index of 0.250-0.390. Ultrasound-assisted encapsulation process did not lead to a decrease in the antioxidant activity of the trapped peptides. FTIR has indicated an effective hydrophobic interaction between phosphatidylcholine and hydrolysate peptides. TEM and SEM have confirmed the spherical nanocarrier structure and unilamelarity. Prolonged gastrointestinal release and stability of peptides have been enabled by liposome nanocarriers.

Improvement of As(V) Adsorption by Reduction of Granular to Micro-Sized Ferric Hydroxide

The remediation of groundwater containing arsenic is a problem that has been addressed using adsorption processes with granulated materials in columns, but the remediation itself could be improved by using micro-sized adsorbents in stirred systems. In this study, arsenate (As(V)) batch adsorption experiments were performed using granular ferric hydroxide (GFH) and two derived micro-sized materials. Reduced-size adsorbents were produced by energetic ball milling, giving final sizes of 0.1–2 µm (OF-M samples) and ultra-sonication, producing final sizes of 2–50 µm (OF-U samples). Equilibrium isotherm studies showed that the Langmuir model was a good fit for the three sorbents, with the highest maximum adsorption capacity (qmax) for OF-U and the lowest for OF-M. The adsorption of the two groundwater samples occurred according to the obtained equilibrium isotherms and indicated the absence of interfering agents for the three adsorbents. Batch kinetics tests in stirred beakers followed a pseudo second-order model and indicated that the kinetics of the OF-U sorbent was faster than the kinetics of the GFH sorbent. The tests also showed an increase in the qe values for the reduced-size sorbent. The application of ultrasonication to the GFH produced an increase of 23 % in the qmax and b term and an increase of 34-fold for the kinetic constant (k2) in the stirred batch systems tested. These results suggest that this new approach, based on ultra-sonication, has the potential for improving the adsorption of arsenic in groundwater.

Ultrasonic Waves Regulate Antioxidant Defense and Gluconeogenesis to Improve Germination From Naturally Aged Soybean Seeds.

Soybean seeds contain substantial triacylglycerols and fatty acids that are prone to oxidation during storage, contributing to the dramatic deterioration of seed vigor. This study reports an ultrasonic waves treatment (UWT), which is a physical method capable of promoting the germination ability of the aged soybean seeds by regulating the antioxidant defense and gluconeogenesis. Germination test revealed that UWT significantly increased the germination rate and seedlings’ establishment of the soybean seeds stored for 12 months, although insignificantly impacting the vigor of fresh (stored for 1 month) and short-term stored (for 6 months) seeds. Further biochemical analysis revealed that UWT decreased the hydrogen peroxide (H2O2), O2⋅–, and malondialdehyde contents in the aged soybean seeds during early germination. Consistently, UWT prominently elevated the activities of superoxide dismutase, catalase, and acetaldehyde dehydrogenase, and also the corresponding gene expressions. Besides, the soluble sugar content of UWT was significantly higher than that of the untreated aged seeds. Analysis of enzyme activity showed UWT significantly upregulated the activities of several key enzymes in gluconeogenesis and the transcription levels of corresponding genes. Moreover, UWT enhanced the invertase activity within aged seeds, which was responsible for catalyzing sucrose hydrolysis for forming glucose and fructose. In summary, UWT improved germination and seedlings establishment of aged soybean seeds by regulating antioxidant defense and gluconeogenesis. This study expands the application of ultrasonication in agricultural production and further clarifies the physiological and molecular mechanisms of the aged seed germination, aiming to provide theoretical and practical guidance for seed quality and safety.

Ultrasound-Assisted facile synthesis of Ce/Fe nanoparticles impregnated activated carbon for fluoride remediation

Fluoride contamination is a severe problem affecting the safety of drinking water around the world. The study focused on the facile synthesis of activated carbon (AC) impregnated with cerium and iron via ultrasonication and performance evaluation of these novel adsorbents using sono-sorption for defluoridation of drinking water. The use of ultrasound demonstrated maximum removal efficiency of 95.4% just after 20 min compared to shaker, where only 87% fluoride was removed after 60 min using AC having Ce/Fe molar ratios of 2:1 (AC/Ce/Fe–1). The key finding which makes our study outstanding is the rapid increase in adsorption rate upon application of ultrasonication while improving the adsorption capacity. The kinetics data obtained was best fitted with the pseudo-second-order model. The maximum adsorption capacity of AC/Ce/Fe–1 was obtained as 52.3 mg/g at room temperature and the synthesized material maintained its relatively high fluoride uptake up to the fourth cycle. The material shows the highest adsorption capacity as compared to the metal-modified AC available in the literature, making it ideal for fluoride removal from drinking water.

Physicochemical and Functional Modifications of Hemp Protein Concentrate by the Application of Ultrasonication and pH Shifting Treatments.

According to the Food and Agriculture Organization (FAO), protein demand is expected to increase globally by around 40% by 2030 as a response to the world’s population growth. Due to their clean label, vegan or vegetarian based applications, nutritional value, and cost-efficient properties, plant-based proteins have been widely studied. However, most of the alternatives currently found in the market have some challenges because of their poor solubility, emulsifying, gelling, and foaming attributes. Hemp seed protein has gained increasing attention due to its unique amino acids and fatty acids profiles. In this study, commercial HPC mixtures were adjusted to pH 2, 4, 6, 8, 10, and 12 followed by ultrasonication (US) for 5 min (5 s on: 5 s off) and incubated for an hour before neutralizing to pH 7. Following the treatments, the samples were analyzed for their hydrodynamic diameter, conductivity, zeta potential, polydispersity index, surface hydrophobicity, solubility, electrophoresis (SDS-PAGE), free sulfhydryl group, and optical characteristics. The samples treated with ultrasound at pH 8 and 10 significantly (p < 0.05) enhanced the solubility of the hemp seed protein by 12.12% and 19.05%, respectively. Similarly, the samples treated with ultrasonication and pH shifting at pH 6, 8, and 10 also significantly increased the amount of free sulfhydryl content (p < 0.05) to 41.6, 58.72, and 46.54 mmol/g from 32.8 mmol/g, respectively. This study shows that the application of ultrasonication and pH shifting is a promising alternative method to modify the functional properties of HPC and widen their applications in the food, cosmetics, and pharmaceutical industries.

Conjoint application of ultrasonication and redox pair mediated free radical method enhances the functional and bioactive properties of camel whey-quercetin conjugates

Ultrasonication, redox-pair generated free radical method and their combination (Ultrasonication/redox-pair method) was used for production of camel whey-quercetin conjugates. FTIR and SDS-PAGE confirmed successful production of whey-quercetin conjugates using ultrasonication and ultrasonication/redox-pair method. FTIR suggested existence of covalent (appearance of new peak at 3399 cm−1) and non-covalent linkages (shifting of peak at 3271 cm−1, 1655 cm−1 (amide I), 1534 cm−1 and 1422 cm−1 (Amide II)) in the whey-quercetin conjugates. Moreover, SDS-PAGE of conjugates produced by ultrasonication as well redox-pair method indicated shifting of protein bands slightly towards high molecular weight due to increase in the mass of proteins due to the binding of polyphenols. All conjugates showed improved techno-functional and bioactive properties in comparison to whey proteins. Conjugates produced through ultrasonication showed smaller particle size, improved solubility, emulsifying and foaming properties while conjugates produced through ultrasonication/redox-pair method depicted superior antioxidant properties in comparison to whey. Furthermore, conjugated samples showed higher inhibition of enzymatic markers involved in diabetes and obesity with highest potential recorded in conjugates produced using ultrasonication. Therefore, ultrasonication can be successfully used individually as well as in combination with redox-pair for production of whey-quercetin conjugates with enhanced bioactive and techno-functional properties.

Ultrasonication promotes extraction of antioxidant peptides from oxhide gelatin by modifying collagen molecule structure

This study primarily explored the internal mechanism underlying the ultrasonication-induced release of antioxidant peptides. An oxhide gelatin solution was treated ultrasonically (power = 200, 300, and 400 W), followed by enzymatic hydrolysis and structural and morphological analysis. The results showed that ultrasonication increased not only the degree of hydrolysis (DH) and protein recovery rate of the oxhide gelatin but also the ABTS radical scavenging, DPPH radical scavenging, ferrous chelating, and ferric reducing activities of its hydrolysate. The oxhide gelatin hydrolysate treated with 300-W ultrasonication had the maximum antioxidant activities. Ultrasonication inhibited hydrogen bond formation, reduced the crosslinking between collagen molecules, transformed part of the folded structure into a helical structure, and lowered the thermal stability of collagen molecules. The micromorphological analysis revealed that ultrasonication caused the gelatin surface to become loose and develop cracks, and as the power of the ultrasonication increased, the repetition interval distance (dÅ) also increased. Moreover, ultrasonication improved the solubilization, surface hydrophobicity, and interface characteristics and increased the content of basic and aromatic amino acids in the hydrolysate. In conclusion, ultrasonication modifies the protein structure, which increases the enzyme’s accessibility to the peptide bonds and further enhances antioxidant peptide release. These findings provide new insights into the application of ultrasonication in the release of antioxidant peptides.

Enhanced heavy metal leaching from sewage sludge through anaerobic fermentation and air-assisted ultrasonication

Interest in using stabilized sewage sludge in agriculture is mainly to benefit from its nutrient content, soil conditioning properties, and water holding capacity. Therefore, sludge management practice needs to be directed from treatment liability towards the recovery of chemical assets embedded in sludge. In this study, anaerobic fermentation process integrated with a new treatment method; i.e., air-assisted ultrasonication, was used to assess the leaching of heavy metals (HM) from waste activated sludge (WAS). Fermentation processes resulted in 9390 mg COD/L of volatile fatty acids (VFAs) production, 26% Ni solubilization and up to 3.4% solubilization of other target metals (Cu and Zn). Application of the air-assisted ultrasonication as a post-treatment to fermentation process stimulated the migration and transformation of HMs to the liquid fraction of the digestate. Applying specific energy input greater than 9 kJ/g total solids (TS) through ultrasonication and supplying air with constant flow rate of 0.875 L of air/(L of digestate.min) resulted in leaching of more than 83% of Ni, 82% of Cu and 80% of Zn.