Ultrasound assisted supercritical fluid extraction of oil and coixenolide from adlay seed

Oil and coixenolide are important components of adlay seed (Coix lachrymal-jobi L. var. Adlay) with many beneficial functions to human health. In this work, a novel extraction technique--ultrasound assisted supercritical fluid extraction (USFE)--was studied. Effects of operating conditions on the extraction, including extraction temperature (T), pressure (P), time (t), CO(2) flow rate (F) and ultrasonic power (I) were investigated. There are optimum temperatures which gives the maximum extraction yields (EYs) for the supercritical fluid extractions with and without ultrasound. The effect of pressure on EYs for is similar to that of pressure on CO(2) density. Based on the yield of extraction, the favorable conditions for supercritical fluid extraction (SFE) were: T at 45 degrees C, P at 25 MPa, t at 4.0 h and F at 3.5L/h. While ultrasound was applied as in USFE, the following parameters were preferred: T at 40 degrees C, P at 20 MPa, t at 3.5h and F at 3.0 L/h, respectively. The results show that supercritical fluid extraction with the assistance of ultrasound could reduce the temperature, pressure, CO(2) flow rate, as well as time used in the process. Compared with SFE, USFE could give a 14% increase in the yield for extracting oil and coixenolide from adlay seed with less severe operating conditions.     

High-power ultrasonic system for the enhancement of mass transfer in supercritical CO2 extraction processes

Oil is an important component of almonds and other vegetable substrates that can show an influence on human health. In this work the development and validation of an innovative, robust, stable, reliable and efficient ultrasonic system at pilot scale to assist supercritical CO₂ extraction of oils from different substrates is presented. In the extraction procedure ultrasonic energy represents an efficient way of producing deep agitation enhancing mass transfer processes because of some mechanisms (radiation pressure, streaming, agitation, high amplitude vibrations, etc.).A previous work to this research pointed out the feasibility of integrating an ultrasonic field inside a supercritical extractor without losing a significant volume fraction. This pioneer method enabled to accelerate mass transfer and then, improving supercritical extraction times. To commercially develop the new procedure fulfilling industrial requirements, a new configuration device has been designed, implemented, tested and successfully validated for supercritical fluid extraction of oil from different vegetable substrates.     

Ultrasonic enhancement of the supercritical extraction from ginger

This work examines the concurrent use of power ultrasound during the extraction of pungent compounds from a typical herb (ginger) with supercritical CO₂. A power ultrasonic transducer with an operating frequency of 20 kHz is connected to an extraction vessel and the extraction of gingerols from freeze-dried ginger particles (4–8 mm) is monitored. In the presence of ultrasound, we find that both the extraction rate and the yield increase. The higher extraction rate is attributed to disruption of the cell structures and an increase in the accessibility of the solvent to the internal particle structure, which enhances the intra-particle diffusivity. While cavitation would readily account for such enhancement in ambient processes, the absence of phase boundaries should exclude such phenomena above the critical point. Possible alternate mechanisms for the cell structure damage are discussed.     

Comparative study of ultrasonic pretreatment and ultrasound assisted three phase partitioning for extraction of custard apple seed oil

Custard apple seed oil is a marketable product extracted from custard apple seed which is a potential agriculture waste. The present work aims to elucidate simultaneous extraction of the custard apple seed oil and proteins using three phase partitioning (TPP). The efficient oil extraction was executed by optimization of parameters including time, slurry ratio, salt concentration, and slurry to t-butanol ratio. Additionally, the application of ultrasound as process intensification tool for TPP was studied that reduces the time of conventional TPP and increases the yield by 2.53%. The work also comprises a comparative study of two modes of ultrasound application, namely ultrasound pre-treatment and simultaneous ultrasound assisted TPP. This work proves ultrasonic pre-treatment followed by TPP as a superior mode of ultrasound application that attributes 33.6 ± 0.56% (w/w) oil extraction with optimized pre-treatment time of 150 s, 30 W ultrasound power and 75% duty cycle. Extraction kinetics studied for conventional, Ultrasound assisted Three Phase Partitioning (UTPP), and Ultrasound Pre-treatment assisted Three Phase Partitioning (UPTPP) were observed to fit Peleg’s model.     

Optimization design of high power ultrasonic circular ring radiator in coupled vibration

This paper presents a new high power ultrasonic (HPU) radiator, which consists of a transducer, an ultrasonic horn, and a metal circular ring. Both the transducer and horn in longitudinal vibrations are used to drive a metal circular ring in a radial-axial coupled vibration. This coupled vibration cannot only generate ultrasound in both the radial and axial directions, but also focus the ultrasound inside the circular ring. Except for the radial-axial coupled vibration mode, the third longitudinal harmonic vibration mode with relative large vibration amplitude is also detected, which can be used as another operation mode. Overall, the HPU with these two vibration modes should have good potential to be applied in liquid processing, such as sonochemistry, ultrasonic cleaning, and Chinese herbal medicine extraction.     

Ultrasound pretreatment of wheat dried distiller’s grain (DDG) for extraction of phenolic compounds

Wheat Dried distiller’s grain (DDG), a coproduct from the ethanol production process, is rich in potentially health-promoting phenolic compounds. In the extraction of phenolic compounds from DDG, the DDG cell wall is an important barrier for mass transfer from the inside to the outside of the cell. The effect of high-power ultrasound pretreatment on destruction of DDG cell walls and extraction yield and rate was investigated. Direct sonication by an ultrasound probe horn at 24 kHz was applied and factors such as ultrasound power and treatment time were investigated. The method of nitrogen (N₂) adsorption at 77 K was used as a means to determine and compare the changes in physical properties (specific surface area, pore volume and pore size) of the treated samples at different levels of ultrasound power and treatment time. Increasing specific surface area, pore volume and pore size caused by ultrasonic treatment implied development of new or larger pores and damaged cell walls. Also, it was observed that the ultrasound pretreatment of DDG particles increased the extraction yield and rate of phenolic compounds from DDG by 14.29%. Among tested ultrasound conditions, 100% ultrasound power for 30 s was evaluated as the best pretreatment condition.     

Extraction of natural products using supercritical fluids and pressurized liquids assisted by ultrasound: Current status and trends

Natural products are a source of a wide range of chemical compounds, from pigments to bioactive compounds, which can be extracted and used in different applications. Due to consumer awareness, the interest in natural compounds significantly increased in the last decades, prompting the search for more efficient and environmentally friendly extraction techniques and methods. Pressurized liquids and fluids (sub and supercritical) are being explored to extract natural compounds within the green process concept. The combination of these techniques with ultrasound has emerged as an alternative to intensify the extraction process efficiently. In this context, this work presents a comprehensive review and current insights into the use of high-pressure systems, specifically supercritical fluid extraction and pressurized liquid extraction assisted by ultrasound, as emerging technologies for extracting bioactive compounds from natural products. The extraction mechanisms, applications, and the influence of operational parameters in the process are addressed, in addition to an analysis of the main challenges to be overcome for widespread application.     

双频超声交替强化超临界流体萃取装置的设计与应用

本文针对超临界流体萃取（SFE）系统设备的特点，设计丁可用于强化SFE过程的双频超声波交替强化装置。以香椿叶中黄酮类化合物为提取对象，对超声强化USFE过程的影响因素及强化效果进行了实验研究，结果表明；低频超声利于提取，频率为20kHz的超声强化的萃取率最大，38kHz的超声最小，两者交替的居于中间。     

Green ultrasound-assisted extraction of carotenoids from pomegranate wastes using vegetable oils

The objective of this work was to develop a new process for pomegranate peels application in food industries based on ultrasound-assisted extraction of carotenoids using different vegetable oils as solvents. In this way, an oil enriched with antioxidants is produced. Sunflower oil and soy oil were used as alternative solvents and the effects of various parameters on extraction yield were studied. Extraction temperature, solid/oil ratio, amplitude level, and extraction time were the factors investigated with respect to extraction yield. Comparative studies between ultrasound-assisted and conventional solvent extraction were carried out in terms of processing procedure and total carotenoids content. The efficient extraction period for achieving maximum yield of pomegranate peel carotenoids was about 30 min. The optimum operating conditions were found to be: extraction temperature, 51.5 °C; peels/solvent ratio, 0.10; amplitude level, 58.8%; solvent, sunflower oil. A second-order kinetic model was successfully developed for describing the mechanism of ultrasound extraction under different processing parameters.     

用微扰理论推算超临界流体比定容热容

本文利用统计热力学中的BH微扰理论建立数学模型,推算了Ar超临界区域比定容热容,与文献值比较平均偏差为9.54%。引入了修正函数,重新对比热容公式进行推导,再次对Ar超临界区域部分比定容热容进行计算,计算平均偏差0.39%。对CO、CO₂、CH₄等其余11种简单气体的超临界比定容热容进行计算,平均偏差在1%左右。最后给出了计算中各物质势能参数值。     

地质样品中有机物的超临界萃取研究

建立了以CO2为超临界流体的超临界萃取地质样品中有机物的分析方法,讨论和优化了超临界萃取条件,测定了茂名油页岩中的n-C13-n-C34,并与索式抽提结果作了对比,该方法测定茂名油页岩中的n-C15-n-C34链烷烃,相对标准偏差为（n=4)4.9%-23.8%,n-C13的相对标准偏差为9．2％（n=4),而传统经黄的索式抽提法测得的n=C15-n-C34链烷烃的相对标准偏差为11．2％－37．7％（n=4),n-C13的相对标准偏差为46．4％（n=4),本法与传统方法相比,具有高效,无热降解,无毒,选择性好,精密度好等优点,可直接用于GC,GC－MS的测定。     

Effect of ultrasound and green solvents addition on the oil extraction efficiency from rapeseed flakes

The current procedure of rapeseed oil extraction is based on a first extraction step by pressing followed by a second extraction step with hexane. This solvent being toxic for the users, the consumers and the environment, its use could be forbidden within the coming years. Stimulated by a stringent regulation, the research activity for the replacement of toxic solvents shows a significant development. The aim of this study was to select alternative solvent to hexane such as ethanol or isopropanol, and, to adjust the oil extraction process by developing an ultrasound assisted method. The objective was to reach a comparable efficiency but also to enhance the oil quality. When applied to isopropanol, the ultrasound assisted extraction method has shown promising results, and comparable to those obtained with hexane (oil yield of 80% for hexane and 79% for isopropanol at optimum extraction conditions (20 min of ultrasound pretreatment followed by 2 h of additional solid/liquid extraction)). Conversely, in studied conditions, ethanol did not seem to be an appropriate alternative solvent to hexane as the extraction yields obtained by using this solvent were quite low.     

Quantitative determination of oil content in small quantity of oilseed rape by ultrasound-assisted extraction combined with gas chromatography

Accurately quantitative determination of oil content in oilseed rape plays an important role in varieties breeding for improving oil content in seeds. However, large quantity of oilseeds were needed in order to obtain accuracy and precision results by using standard Soxhlet extraction method, which may be a handicap in analysis of small, rare and precious samples in plant breeding. In the present work, ultrasound-assisted extraction was evaluated as a simpler and more effective alternative to conventional extraction method for the isolation of oil from small quantity of oilseed rape (<20 mg). The oil of oilseed rape samples was extracted by ultrasound-assisted method, and then the fatty acids and total oil content of the seeds were qualitatively and quantitatively determined by gas chromatography (GC). Extraction efficiency of total oil obtained by ultrasound-assisted extraction through an orthogonal experiment (L(9) (3(4))) were investigated to get the best extraction conditions. Statistical analysis showed that the variable with the largest effect was the ultrasound-assisted extraction time which was followed by the ultrasound-assisted extraction power, and the liquid:solid ratio. A liquid:solid ratio of 1:4 (L:g), an ultrasound-assisted extraction time of 60 min and an ultrasound-assisted extraction power of 500 W were found to be optimal for oil extraction from oilseed rape. By comparing with the conventional method, it was found that the ultrasound-assisted extraction of oil from oilseed rape was about five times faster than the traditional extraction method. By the use of ultrasound-assisted extraction combined with GC analysis, the fatty acids and total oil content in small quantity of seeds (<20 mg) were successfully qualitatively determined and the results are in agreement with that obtained by traditional standard method.     

Comparison between the use of polyether ether ketone and stainless steel columns for ultrasonic-assisted extraction under various ultrasonic conditions

The ultrasound-assisted extraction (UAE) was conducted using the stainless steel (SS) and polyether ether ketone (PEEK) columns and analyzed with high-performance liquid chromatography (HPLC) to understand the mechanism of ultrasound-assisted chromatography (UAC). Empty SS and PEEK columns were used to extract dyes from a fabric under identical conditions with several parameters including the initial ultrasonic bath temperatures (30 °C and 40 °C), ultrasound power intensities (0, 20, 40, 60, 80, and 100 %), ultrasound operation modes (normal and sweep), and ultrasound frequencies (25 kHz, 40 kHz, and 132 kHz) to compare their extraction capabilities. After 30 min of extraction, the amount of extract was determined by HPLC. The PEEK material was significantly affected by ultrasonic radiation compared to the SS material, especially at a higher temperature (40 °C), power intensity (100 %), and frequency (132 kHz) with sweep mode. At a maximum power density of 45 W/L, the extraction effectiveness ratio of PEEK to SS was in the range of 1.8 - 3.9 depending on the specific frequency, initial temperature, and with or without temperature control. The most optimal ultrasound frequencies, in terms of enhancing extraction effectiveness, are in the order of 132 kHz, 40 kHz, and 25 kHz. Unlike the SS material, the PEEK material was more affected by temperature and acoustic effects under identical conditions, especially at 132 kHz ultrasound frequency. In contrast, at lower frequencies of 40 kHz and 25 kHz, no significant differences in the acoustic effects were observed between the PEEK and SS materials. The findings of this study contribute to elucidating the roles of column materials in UAE and UAC.     

Combining pressurized liquids with ultrasound to improve the extraction of phenolic compounds from pomegranate peel (Punica granatum L.)

The combination of ultrasound and pressurized liquid extraction (UAPLE) was evaluated for the extraction of phenolic compounds from pomegranate peels (Punica granatum L.). The influence of several variables of the process on extraction yield, including solvent type (water, ethanol + water 30, 50 and 70% v:v), temperature (50–100 °C), ultrasound power (0–800 W at the generator, or 0–38.5 W at the tip of the probe), mean particle size (0.68 and 1.05 mm), and number of cycles (1–5), were analyzed according to the yield of 20 different phenolic compounds. The most suitable temperatures for the extraction of phenolic compounds using water were from 70 to 80 °C. In general, 100 °C was not adequate since the lowest extraction yields were observed. Results suggested that ultrasound had a greater impact on extraction yields using large particles and that intermediate ultrasound power (480–640 W at the generator, or 23.1–30.8 W at the tip of the probe) produced the best results. Using small particles (0.68 mm) or large particles (1.05 mm), extraction with ultrasound was 1 cycle faster. Ultrasound may have offset the negative effect of the use of large particles, however, did not increase the yield of phenolic compounds in any of the cases studied after five cycles. Additionally, the continuous clogging problems observed with small particles were avoided with the use of large particles, which combined with ultrasound allowed consistent operation with good intra and inter-day reproducibility (>95%). Using samples with large particle size, the best extraction conditions were achieved with water extraction solvent, 70 °C extraction temperature, ultrasound power at 480 W, and 3 cycles, yielding 61.72 ± 7.70 mg/g. UAPLE demonstrated to be a clean, efficient and a green alternative for the extraction of phenolic compounds from pomegranate peels. These findings indicate that UAPLE has a great potential to improve the extraction of bioactive compounds from natural products.     

Effects of ultrasonic irradiation on crystallization kinetics,morphological and structural properties of zeolite FAU

In this work, NaX zeolite was synthesized and the effect of ultrasound irradiation on reaction kinetics, morphological and structural properties was investigated. Ultrasound was applied, by using a plate transducer (91.8 kHz), for the first time during the crystallization of zeolite NaX, at high temperature, varying the irradiation moment and its duration. Furthermore, ultrasound was applied after the crystallization by a horn-type transducer (20–24 kHz) at low temperature. The effects of irradiated volume (100–300 mL), sonication time (2–10 min) and ultrasound power (10–200 W) were studied with a power intensity up to 100 W/cm². It was found that the application of ultrasound during the first hour of crystallization resulted in 20% reduction of reaction time compared to a standard crystallization. Ultrasound can also reduce the agglomeration degree of the final powder by combining high power and long sonication time. After 5 min sonication time at 0.3 W/mL, the tapped density of the powder was increased by 10%, from 0.37 to 0.41 g/mL. Finally, by scanning electron microscopy (SEM) it was demonstrated that ultrasound can disrupt the agglomerates without affecting the morphology of individual crystals.     

Optimization of ultrasonic-assisted extraction of pomegranate (Punica granatum L.) seed oil

The effectiveness of ultrasonic-assisted extraction (UAE) of pomegranate seed oil (PSO) was evaluated using a variety of solvents. Petroleum ether was the most effective for oil extraction, followed by n-hexane, ethyl acetate, diethyl ether, acetone, and isopropanol. Several variables, such as ultrasonic power, extraction temperature, extraction time, and the ratio of solvent volume and seed weight (S/S ratio) were studied for optimization using response surface methodology (RSM). The highest oil yield, 25.11% (w/w), was obtained using petroleum ether under optimal conditions for ultrasonic power, extraction temperature, extraction time, and S/S ratio at 140 W, 40 °C, 36 min, and 10 ml/g, respectively. The PSO yield extracted by UAE was significantly higher than by using Soxhlet extraction (SE; 20.50%) and supercritical fluid extraction (SFE; 15.72%). The fatty acid compositions were significantly different among the PSO extracted by Soxhlet extraction, SFE, and UAE, with punicic acid (>65%) being the most dominant using UAE.     

Quantitative estimation of ultrasound beam intensities using infrared thermography-Experimental validation

Infrared (IR) thermography is a technique that has the potential to rapidly and noninvasively determine the intensity fields of ultrasound transducers. In the work described here, IR temperature measurements were made in a tissue phantom sonicated with a high-intensity focused ultrasound (HIFU) transducer, and the intensity fields were determined using a previously published mathematical formulation relating intensity to temperature rise at a tissue/air interface. Intensity fields determined from the IR technique were compared with those derived from hydrophone measurements. Focal intensities and beam widths determined via the IR approach agreed with values derived from hydrophone measurements to within a relative difference of less than 10%, for a transducer with a gain of 30, and about 13% for a transducer with a gain of 60. At axial locations roughly 1 cm in front (pre-focal) and behind (post-focal) the focus, the agreement with hydrophones for the lower-gain transducer remained comparable to that in the focal plane. For the higher-gain transducer, the agreement with hydrophones at the pre-focal and post-focal locations was around 40%.     

Ultrasound induced green solvent extraction of oil from oleaginous seeds

Ultrasound-assisted extraction of rapeseed oil was investigated and compared with conventional extraction for energy efficiency, throughput time, extraction yield, cleanness, processing cost and product quality. A multivariate study enabled us to define optimal parameters (7.7 W/cm² for ultrasonic power intensity, 40 °C for processing temperature, and a solid/liquid ratio of 1/15) for ultrasound-assisted extraction of oil from oilseeds to maximize lipid yield while reducing solvent consumption and extraction time using response surface methodology (RSM) with a three-variable central composite design (CCD). A significant difference in oil quality was noted under the conditions of the initial ultrasound extraction, which was later avoided using ultrasound in the absence of oxygen. Three concepts of multistage cross-current extraction were investigated and compared: conventional multistage maceration, ultrasound-assisted maceration and a combination, to assess the positive impact of using ultrasound on the seed oil extraction process. The study concludes that ultrasound-assisted extraction of oil is likely to reduce both economic and ecological impacts of the process in the fat and oil industry.     

Highly efficient sonochemical reaction with a switched spiral focal field

This paper describes an efficient method of inducing sonochemical reactions with focussed ultrasound. A sector-vortex transducer (a phased array transducer with multiple sectors and a geometric focus) is used to produce focal ultrasound fields with spiral-shaped wavefronts. Clockwise and counter-clockwise spiral focal fields, with basically the same ultrasound power distribution but having different wavefront angles, are produced by using the same array transducer. The oxidation of the iodide ions induced from the periodic switching between such a pair of spiral focal fields is investigated at an ultrasound frequency of 750 kHz. The oxidation rate at the optimum switching period (3 ms) is about ten times higher than that at switching periods of 1 s. The optimum switching period and the sonochemical reaction rate are unchanged when the viscosity was adjusted to that of human blood.