Ultrasonics Sonochemistry

Growing fruit and vegetable processing industries generates a huge amount of by-products in the form of seed, skin, pomace, and rind containing a substantial quantity of bioactive compounds such as polysaccharides, polyphenols, carotenoids, and dietary fiber. These processing wastes are considered to be of negligible value compared to the processed fruit or vegetable due to lack of sustainable extraction technique. Conventional extraction has certain limitations in terms of time, energy, and solvent requirements. Ultrasound assisted extraction (UAE) can extract bioactive components in very less time, at low temperature, with lesser energy and solvent requirement. UAE as a non-thermal extraction technique is better equipped to retain the functionality of the bioactive compounds. However, the variables associated with UAE such as frequency, power, duty cycle, temperature, time, solvent type, liquid-solid ratio needs to be understood and optimized for each by-product. This article provides a review of mechanism, concept, factor affecting extraction of bioactive compounds with particular focus on fruit and vegetable by-products.

The increasing focus on health and well-being has sparked a rising interest in bioactive components in the food, pharmaceutical, and nutraceutical industries. These components are gaining popularity due to their potential benefits for overall health. The growing interest has resulted in a continuous rise in demand for bioactive components, leading to the exploration of both edible and non-edible sources to obtain these valuable substances. Traditional extraction methods like solvent extraction, distillation, and pressing have certain drawbacks, including lower extraction efficiency, reduced yield, and the use of significant amounts of solvents or resources. Furthermore, certain extraction methods necessitate high temperatures, which can adversely affect certain bioactive components. Consequently, researchers are exploring non-thermal technologies to develop environmentally friendly and efficient extraction methods. Ultrasonic-assisted extraction (UAE) is recognized as an environmentally friendly and highly efficient extraction technology. The UAE has the potential to minimize or eliminate the need for organic solvents, thereby reducing its impact on the environment. Additionally, UAE has been found to significantly enhance the production of target bioactive components, making it an attractive method in the industry. The emergence of ultrasonic assisted extraction equipment (UAEE) has presented novel opportunities for research in chemistry, biology, pharmaceuticals, food, and other related fields. However, there is still a need for further investigation into the main components and working modes of UAEE, as current understanding in this area remains limited. Therefore, additional research and exploration are necessary to enhance our knowledge and optimize the application of UAEE. The core aim of this review is to gain a comprehensive understanding of the principles, benefits and impact on bioactive components of UAE, explore the different types of equipment used in this technique, examine the various working modes and control parameters employed in UAE, and provide a detailed overview of the blending of UAE with other emerging extraction technologies. In conclusion, the future development of UAEE is envisioned to focus on achieving increased efficiency, reduced costs, enhanced safety, and improved reliability. These key areas of advancement aim to optimize the performance and practicality of UAEE, making it a more efficient, cost-effective, and reliable extraction technology.

Oleosomes are intracellular lipid-storage organelles found in oilseeds and represent a promising yet underexplored source of proteinaceous emulsifiers for structuring food-grade colloidal systems. In this study, extrinsic proteins (OP) from soybean oleosomes were extracted under controlled alkaline-ultrasonic treatment (0–400 W) to elucidate how ultrasound-mediated protein remodeling governs interfacial adsorption kinetics, high-internal-phase emulsion (HIPE) formation, rheological behavior, and probiotic protection. Alkaline-ultrasonic treatment from 0 to 300 W significantly increased the protein recovery from 40.15% to 58.84%, solubility from 74.10% to 87.61%, and zeta potential from −8.81 to −13.31 mV, while reduced the particle size from 651 to 389 nm. Spectroscopic analyses revealed controlled protein remodeling characterized by increased exposure of hydrophobic and aromatic residues, reduced α-helix content from 22.95% to 15.03%, and increased β-sheet structures from 34.16% to 42.14%. Ultrasonic treatment (300 W) effectively improved the protein diffusion rate (0.106 to 0.182 mNm −1 s −0.5 ) and penetration rate (3.971 × 10 −4 to 4.682 × 10 −4 s −1 ) at the oil–water interface, indicating the formation of strengthened interfacial protein films. HIPEs stabilized by OP-300 revealed the smallest droplet size, intensified droplet–droplet interactions, superior viscoelastic properties, and excellent storage stability. LAOS analysis further confirmed that HIPEs prepared with OP-200 and OP-300 maintained structural integrity under large deformation amplitudes ≤100%, compared to the untreated sample ≤10%, indicating the formation of stronger and more cohesive gel networks. Moreover, encapsulated Lactobacillus reuteri showed improved survival rate during simulated digestion, increasing viable cell counts from 4.12 × 10 7 to 7.21 × 10 7 CFU/mL. These findings established that ultrasound tailors OP structure–function relationships, enabling their use as sustainable emulsifiers for robust HIPEs with enhanced probiotic delivery.

Non-thermal ultrasound (US) is a powerful processing technology that alters the textural, physicochemical, and volatile properties of novel foods such as cultured meat, plant-based meat alternatives (PBMA), precision fermentation-derived products, insect-based proteins, and algae-based foods through cavitation-driven acoustic effects. These changes directly affect the sensory attributes that shape consumer perceptions and acceptance of novel foods. This review examines the mechanistic relationship between US food processing and the consumer sensory-acceptance barrier, drawing on evidence from sonochemistry, behavioral economics, sensory science, food policy, and digital marketing. We stated that US-induced modifications in flavor (through modulation of Maillard reaction precursors, volatile compound generation, and lipid oxidation control), texture (through starch gelatinization, emulsion stabilization, and myofibrillar disruption), aroma (through controlled release of encapsulated volatile compounds), and color (through Maillard browning and pigment stability) potentially contribute to consumer acceptance by affecting sensory attributes. However, these relationships should be considered as proposed pathways rather than experimentally validated causal mechanisms, as direct consumer acceptance studies remain limited. Specifically, US-modified flavor and texture profiles of PBMAs, microalgae ingredients, and insect protein powders address the most consistently cited sensory barriers to consumer trial and repeat purchase. The review further combines cross-domain moderators, cultural disgust, food neophobia, behavioral nudges, labeling framing, digital and social media influence, and pricing that operate at higher cognitive and policy levels, demonstrating how US sensory improvements must be coupled with consumer-centered communication strategies to translate physicochemical gains into marketplace acceptance. A comparative analysis of existing studies indicates a persistent attitude-behavior gap, suggesting that US-optimized sensory quality alone does not fully determine consumer acceptance.

This study reports direct experimental observations of shockwave propagation and cavitation bubble formation inside liquid water droplets during high-speed impact (80-180 m/s) on solid surfaces, together with jetting observed at the distal end of the droplet. Ultra-high-speed shadowgraph and angle-view imaging at 10 million frames per second resolved two distinct internal wave structures: a primary compression front (1500-2050 m/s), consistent with pressure-dependent corrections to the acoustic wave speed, and a secondary tension wave emerging approximately 500 ns later, generated by reflection at the curved water-air interface. The curved distal surface focuses converging rarefaction waves into a caustic region, leading to cavitation nucleation 1.2-1.5 µs after impact. The subsequent asymmetric collapse of these cavitation structures drives directed jetting from the distal end, with jet morphology dependent on droplet geometry: coherent jets for smaller spherical droplets (<2 mm) whereas spray-like ejection is typical for larger, elongated droplets (>2 mm). At the proximal end of the droplet, air is entrapped between the surface and the droplet, collapsing into a toroidal-shaped bubble that exhibits oscillations in the 0.5-1.8 MHz range. All presented results, including experimental data and accompanying analysis, provide benchmark validation data for computational models of compressible droplet impact.

This study presents a simple ultrasonication-assisted route for the synthesis of α-MnO 2 nanoflowers at room temperature. The process employs acoustic cavitation at 40 kHz and 100 W with testing synthesis times of 0, 20, 40, and 60 min. The best results were obtained with 40 min of sonication, yielding uniform nanoflower structures with (2 × 2) tunnel framework of α-MnO 2 , a maximum specific BET surface area of 182 m 2 g −1 and total pore volume of 0.41 cm 3 g −1 . Besides, the electrochemical measurements of α-MnO 2 nanoflowers were carried out using a three-electrode configuration, achieving a specific capacitance of 121F g −1 in 1 M Na 2 SO 4 and 116F g −1 in 1 M LiCl electrolytes at 2 mV s −1 for 40 min sonicated sample. Moreover, the electrochemical impedance spectroscopy indicates notable reduction in the charge transfer resistance upon optimization. The fabricated symmetric device exhibits a coulombic efficiency of ∼99% over 10,000 cycles in a 1 M Na 2 SO 4 electrolyte. The ambient, template-free synthesis condition offer clear pathways to industrial scalability. This work establishes sonication duration as a versatile parameter for engineering metal oxides with tailored morphology, delivering reliable performance and long-term stability in neutral aqueous supercapacitors.

Calcium sulfate (gypsum) scale removal is a major operational issue concerning oil production facilities, as the deposits damage equipment and their removal causes prolonged downtime. Therefore, investigating process intensification techniques is pivotal for reducing scale removal time. This study focuses on the application of acoustic cavitation to the dissolution of gypsum, using two different types of dissolvers: potassium carbonate, a converter, and tetrasodium EDTA, a chelating agent. Compared with soaking at ambient temperature, ultrasound-assisted treatment increased gypsum removal 8.5-fold with potassium carbonate and 56-fold with tetrasodium EDTA. Silent experiments following the same temperature profile showed that heating accounts for much of this gain, with cavitation providing a further 1.6-fold and 2.9-fold increase, respectively. Electron microscopy indicated different mechanisms. Potassium carbonate converts gypsum layer by layer under silent conditions, whereas ultrasound produced deep cavities beyond the surface layer, consistent with localized cavitation-induced penetration. With tetrasodium EDTA, surface morphology was unchanged, suggesting that enhanced mass transfer dominates. These bench-scale findings support acoustic cavitation as a process intensification tool for scale removal, warranting further studies on field applicability.

). Rapid solidification generated a metastable B19' martensitic phase and a high density of process-induced defects in the LPBF alloy. Its passive film contained a higher fraction of low-valence oxides (TiO) and exhibited a higher donor density than that of the as-cast alloy, indicating a less protective barrier layer. Failure mechanism analysis revealed that microgalvanic corrosion and stress acted synergistically to accelerate passive-film rupture and substrate damage in the LPBF alloy. These findings establish the relationships among microstructure, passive-film characteristics, electrochemical behaviour, and CE resistance, thereby providing an experimental and mechanistic basis for enhancing the marine-service performance of LPBF NiTi alloys.

Accumulating evidence has demonstrated that ultrasound-assisted lactic acid bacteria (LAB) fermentation can improve the functional quality of fruit juices. However, the growth phase-dependent metabolic responses of LAB to low-frequency ultrasonication remain poorly understood. In this study, low-frequency ultrasonication (83.6 and 119.17 W/L) was applied during the lag, logarithmic, and stationary phases of Lactobacillus acidophilus LA137 fermentation in Citrus aurantium L. juice. Microbial growth, physicochemical properties, β-glucosidase activity, total phenolic and flavonoid contents, and antioxidant capacity were evaluated in this study. Ultrasonication applied during the logarithmic and stationary phases exerted greater effects on microbial metabolism and functional quality than treatment during the lag phase. Among all treatments, ultrasonication at 119.17 W/L during the logarithmic phase (LU4) and 83.6 W/L during the stationary phase (LU5) showed superior enhancement of β-glucosidase activity, phenolic/flavonoid accumulation, and antioxidant capacity. Integrated untargeted metabolomics revealed distinct metabolic responses between LU4 and LU5. LU4 preferentially promoted phenylpropanoid and flavonoid metabolism, resulting in the accumulation of antioxidant-related metabolites, including gallic acid, taxifolin, and 7-galloylcatechin. In contrast, LU5 mainly enhanced amino acid and organic acid metabolism, leading to increased levels of lactic acid, γ-aminobutyric acid, alanine, and serine. Correlation analysis further linked these metabolites to improved antioxidant properties. These findings demonstrate that low-frequency ultrasonication redirects microbial metabolism toward distinct functional routes depending on the growth phase of L. acidophilus, providing new mechanistic insights into the precise regulation of ultrasound-assisted LAB fermentation.

The effect of ultrasound-assisted binary probiotic fermentation on the quality of sugarcane bagasse dietary fiber (SBDF)-added synbiotics yogurt were investigated. The results showed that 0.25 % (w/v) of SBDF significantly reduced yogurt syneresis. Furthermore, ultrasound-assisted fermentation with L. plantarum CGMCC 1.5953 and L. fermentum CGMCC 1.7434 improved the yogurt's texture, rheology, microstructure, and sensory scores. These improvements were supported by metabolomic analysis, which showed an 11.91-fold upregulation of galactitol and decreased concentrations of L-phenylalanine, L-glutamic acid, and L-allothreonine. Integrated sensory and molecular analyses (HS-SPME-GC-MS, UHPLC-MS) identified that enhanced texture scores were associated with SBDF-derived metabolites, including L-erythrulose, α-lactose, and erythritol. Meanwhile, the improved odor scores were associated with increased levels of ethyl acetate, hexanoic acid, and 2-nonanone. Key pathways involve galactose, tyrosine, glycine-serine-threonine metabolism, amino acid biosynthesis, and lysine degradation. This study provides valuable insights for the high-value utilization of sugarcane bagasse dietary fiber and the production of premium-quality yogurt.

Acoustic cavitation is a transient and spatially heterogeneous process that governs energy deposition and mechanical effects during high-intensity focused ultrasound (HIFU) exposure. Active B-mode imaging is attractive for monitoring because it is readily available on clinical ultrasound systems; however, therapy-imaging coupling can introduce drifting stripe artifacts that overlap with cavitation backscatter and compromise gray-level thresholding and region of interest (ROI) based quantification. Here we present an image-domain B-mode framework for cavitation-associated feature separation and spatiotemporal quantification based on singular-value decomposition (SVD) and magnitude-based spectral gating. B-mode sequences are rearranged into a spatiotemporal matrix, decomposed into singular components, and reconstructed into full-field maps of cavitation-associated image features from finite frame stacks. Highly coherent components are assigned to quasi-steady HIFU-related echoes and background scattering, whereas candidate cavitation components are selected according to their spectral-magnitude distribution, allowing stripe components observed in the present B-mode sequences to be suppressed while intermittent candidate cavitation-associated image fluctuations are retained. Experiments in egg-white polyacrylamide gels and ex vivo bovine liver showed that the proposed method suppressed stripe artifacts, improved frame-to-frame consistency, and detected cavitation onset earlier than conventional grayscale thresholding. The image-derived cavitation area increased with both acoustic pressure and pulse length and followed the trends observed in post-exposure axial damage morphology. This unsupervised method requires neither training data nor manual ROI selection, and therefore provides a practical image-based metric for retrospective visualization and quantification of cavitation-associated features during therapeutic ultrasound exposures.

Whole-bean tempeh production is hindered by the compact seed coat of black kidney beans, which restricts fungal colonization and nutrient bioaccessibility. Dehulling, the conventional solution, removes the nutrient-dense outer layer. This study employed ultrasound pretreatment (10-30 min) to modify seed coat structure prior to fermentation with Rhizopus oligosporus, aiming to overcome this barrier while preserving the seed coat. Ultrasound increased seed coat porosity from 0.9% to 4.5%, reduced hardness from 365.7 N to 73.5-116.8 N, and enhanced hydration, thereby facilitating fungal growth and enzyme activity. Ergosterol content, a marker of fungal biomass, increased 9.0-fold over the untreated control. SEC and CLSM further confirmed enhanced protein and starch degradation as well as cell wall disassembly in ultrasound-treated samples. Compared with untreated whole-bean tempeh, ultrasound-pretreated samples achieved 1.4-2.5-fold higher peptide levels, while maintaining moderate starch utilization distinct from the excessive degradation observed in dehulled tempeh. Protein bioaccessibility reached approximately 55%, bridging 37% of the digestibility gap between whole-bean and dehulled samples, yet the estimated glycemic index remained substantially lower (47.3-49.7) than that of dehulled tempeh (67.2). The 20-min treatment provided the best overall performance, demonstrating that controlled ultrasound is a viable strategy for producing nutritionally balanced whole-bean tempeh.