•Dual-frequency multi-angle ultrasound was used for processing of raw soymilk.•Monitored ultrasonic field intensity of 40 + 20 kHz 0° treatment was the largest.•The 40 + 20 kHz 45° treatment ...maximally increased soybean protein content.•Flavor of soymilk was improved by dual-frequency multi-angle ultrasonic treatment.
To improve the soybean protein content (SPC), flavor and quality of soymilk, the effects of dual-frequency ultrasound at different angles (40 + 20 kHz 0°, 40 + 20 kHz 30°, 40 + 20 kHz 45°) on physicochemical properties and soybean protein (SP) structure of raw soymilk were mainly studied and compared with the conventional single-frequency (40 kHz, 20 kHz) ultrasound. Furthermore, the intensity of the ultrasonic field in real-time was monitored via the oscilloscope and spectrum analyzer. The results showed that 40 + 20 kHz 45° treatment significantly increased SPC. The ultrasonic field intensity of 40 + 20 kHz 0° treatment was the largest (8.727 × 104 W/m2) and its distribution was the most uniform. The emulsifying stability of SP reached the peak value (233.80 min), and SP also had the largest particle size and excellent thermal stability. The protein solubility of 40 + 20 kHz 30° treatment attained peak value of 87.09%. 20 kHz treatment significantly affected the flavor of okara. The whiteness and brightness of raw soymilk treated with 40 kHz were the highest and the system was stable. Hence, the action mode of ultrasonic technology can be deeply explored and the feasibility for improving the quality of soymilk can be achieved.
Polyphenols are the largest group of phytochemicals with important biological properties. Their presence in conveniently available low-cost sources, such as agri-food by-products, has gained ...considerable attention in their recovery and further exploitation. Retrieving polyphenols in a green and sustainable way is crucial. Recently, deep eutectic solvents (DESs) have been identified as a safe and environmentally benign medium capable of extracting polyphenols efficiently. This review encompasses the current knowledge and applications of DESs and assisted technologies to extract polyphenols from agri-food by-products. Particular attention has been paid to fundamental mechanisms and potential applications in the food, cosmetic, and pharmaceutical industries. In this way, DESs and DESs-assisted with advanced techniques offer promising opportunities to recover polyphenols from agri-food by-products efficiently, contributing to a circular and sustainable economy.
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•Effects of dry powders and ultrasound on okra pectin characteristics were studied.•Ultrasonic field was monitored to analyze its effect on pectin extraction.•Morphologies of okra ...powders and pectin molecular structure were studied.
Diversiform okra dry powders were prepared and controlled-temperature ultrasonic-assisted extraction (CTUAE) was then utilized to obtain okra pectin (OP) from the preparative powders. During processing of hybrid techniques, 6 types of dry powders were prepared through different drying technologies (hot air drying, HD; freeze-drying, FD) and meshes (60, 80, 120 meshes) at first. Next, the extraction yield, physicochemical and function characteristics, and molecular structure of OP were analyzed with or without CTUAE technique. Meanwhile, the time–frequency domains of acoustic fields during extraction process of OP were monitored to analyze the effects of ultrasonic fields. Results showed that OP main chains with less cracking by FD than that by HD; the yield, GalA, esterification degree (DE), Mw and viscosity of OP increased, but its particle size decreased. Water holding capacity (WHC) and oil holding capacity (OHC) of OP by HD were more prominent. Secondly, HD OP had dendritic rigid chains, while FD OP had flexible chains with multiple branches. For HD OP, as meshes of okra dry powders decreased, GalA, viscosity and emulsification ability decreased; while gel strength and thermal stability increased. For FD OP, the reduction of meshes improved thermal stability. Above all, CTUAE technique increased the yield and GalA, and decreased DE, Mw and particle size of OP. In terms of functional characteristics, the technique also improved gel strength, resilience and viscoelasticity, enhanced emulsifying stability, WHC and thermal stability, and reduced viscosity. Finally, the correlation between functional and structural characteristics of OP was quantified, and some suggestions were made for its application in food areas.
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•Natural ternary deep eutectic solvents deconstructed corn straw without pollution.•Ultrasound and microwave enhanced the deconstruction by deep eutectic solvent.•Ultrasound/microwave ...sequential pretreatment increased cellulose content by 76.08%.•The removal of lignin was 46.44% under mild pretreatment conditions.•The mechanism of deconstruction of corn straw was proposed.
Mild and effective pretreatments are essential to deconstruct lignocellulosic biomass so as to reuse cellulose content for value-added products. In this study, sequential multimode-ultrasound and microwave with natural ternary deep eutectic solvent (NATDES) pretreatments were used to deconstruct corn straw and optimized factors such as NATDES, ultrasonic, and microwave parameters. Results indicated that the ultrasound-NATDES or microwave-NATDES pretreatment could remove 37.86% and 52.36% lignin, respectively. When using sequential multimode-ultrasound and microwave assisted NATDES pretreatment, the delignification efficiency increased to 61.50%, and the cellulose content increased from 34.70% to 76.08%. In addition, the delignification of sequential multimode-ultrasound and microwave assisted NATDES pretreatment (under the mild conditions of microwave heating at 60 °C and 60 min) increased to 57.39%, and the cellulose content increased to 59.98%, too. This highlighted the effect of the combined ultrasound and microwave technology. Finally, the microstructural changes of mercury intrusion porosimeters, scanning electron microscopy, thermogravimetric, X-ray diffraction and Fourier transform mid-infrared spectroscopy were conducted to confirm the effectiveness of this method to deconstruct corn straw. A mechanism of the deconstruction of corn straw biomass in NATDES with the assistance of the sequential multimode-ultrasound and microwave heating was proposed. This research could open a window for future use of biomass energy by deconstructing lignocellulosic biomasses using environmentally friendly pretreatment methods.
•SFU-assisted soybean soaking reduced time by 45.13% and increased SPC by 14.27%.•Ultrasonic field was monitored to explain its effect on soybean soaking.•Cell membrane was more permeable and beany ...flavor reduced in SFU group.•The structure of soybean protein was changed by SFU.
Soybean soaking is important to the processing of bean products, however, restricted by the long soaking time. Herein, the soybean soaking was assisted by 60 kHz sweeping frequency ultrasound (SFU). Shortening mechanism of soaking time and physicochemical properties of soybeans were analyzed. Results showed that soaking temperature of 37 °C, ultrasonic power of 60% (144 W), and soaking time of 214 min were optimum SFU-assisted parameters. The soaking time was reduced by 45.13%, and soluble protein content increased by 14.27% after SFU. Based on analysis of acoustic signals, the maximum voltage amplitude of SFU increased with the increment of oscillation periods of cavitation bubbles, which enlarged the intercellular space and size of soybean, and cell membrane permeability was enhanced by 4.37%. Unpleasant beany flavor compounds were reduced by 16.37%–47.6%. Therefore, SFU could significantly improve the soaking efficiency of soybeans and provide a theoretical basis for the processing enterprises of soybean products.
The effects of processing parameters on essential oil and pectin extractions from orange peels were investigated using response surface approach; 2 × 5 and 3 × 5 central composite rotatable designs ...were adopted for the essential oil and pectin extractions, respectively. Extraction temperatures (80–100 °C) and extraction times (120–240 min) were chosen for essential oil extraction, while extraction temperatures (80–100 min), extraction times (60–120 min), and extraction pH (1.0–3.0) were chosen for pectin extraction. Essential oil yield ranged from 0.57–3.24%, while pectin yield ranged from 12.93–29.05%. The predicted optimum value for essential oil yield was 3.38% at extraction temperature of 95.23 °C and extraction time of 231.30 min, while the predicted optimum value for pectin yield was 30.00% at extraction temperature of 93.07
o
C, extraction time of 117.00 min, and extraction pH of 1.60. Deviations between experimental and predicted values were low and statistically insignificant. All processing factors have significant effects on both extractions. The physicochemical properties of the essential oil and pectin extracted at the optimum conditions fell within tolerable and acceptable range.
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•Effects of moisture content, heating temperature, heating time and applied pressure on oil yield from moringa seeds investigated.•Development of predictive models for mechanical oil ...expression process from moringa seeds.•Optimization of the oil expression process from moringa seeds.
Optimization has found several applications in various processes widely used in the food industry and has been widely applied in solvent oil extraction as well as mechanical oil expression. In this study, the mechanical oil expression process for moringa seeds was optimized. A 4×5 Central Composite Rotatable Design was adopted for the experiments. Experimental factors were moisture content, heating temperature, heating time and applied pressure. Data analyses were done using multiple linear regression at p=0.05. Predicted optimum conditions were validated using experimental values. Oil yield ranged from 11.42 to 28.6% with the highest obtained at moisture content of 11%, temperature of 80°C, duration of 30min and pressure of 20MPa. Mathematical models were developed relating processing factors to oil yield. Coefficient of determination (R2) for the oil yield was 0.77. Predicted optimum oil yield of 28.20% at moisture content of 11.30%, temperature of 85.57°C, duration of 27.17min and pressure of 19.63MPa was obtained. Deviations between experimental and predicted values were low; and it was established that moisture content, applied pressure, heating temperature and duration influenced quantity of oil recovery from moringa seeds using expeller. Overall, the data generated in the study will serve as a useful tool in process and equipment design for moringa oil processors.
Sequential delignification of watermelon rind using ultrasonication and deep eutectic solvent (DES) pretreatment methods was demonstrated in this study. The effects of pretreatment factors on ...delignification were investigated using parametric screening and subsequent optimization of significant factors. Plackett–Burman Design was used for the screening of pretreatment variables, while optimization was performed adopting Central Composite Rotatable Design. For the range of variables considered in the study, the screening experiments revealed that the effects of ultrasonication power, ultrasonication frequency, ultrasonication time, DES reaction temperature and DES reaction time on delignification were significant, while the effects of ultrasonication solid-liquid ratio, ultrasonication temperature, hydrogen bond acceptor/hydrogen bond donor molar ratio, and DES solid-to-liquid ratio were not significant. The significant factors were further investigated and maximum lignin removal of 43.56 % was achieved at ultrasonication power 180 W, ultrasonication frequency 60 kHz, ultrasonication time 40 min, reaction temperature 120°C and reaction time 180 min. Synergistic effect between the two pretreatment methods was observed and it correlated positively with the severity of the ultrasound pretreatment. The SEM and FTIR analyses further established the effectiveness of the sequential combinative pretreatment methods on watermelon rind delignification.
•Novel two-pot approach ultrasound-assisted DES pretreatment was demonstrated.•Effect of pretreatment factors on watermelon rind delignification was investigated.•Synergistic effect between ultrasonication and DES pretreatments was observed.•Synergistic effect correlated positively with severity of ultrasound pretreatment.•SEM and FTIR established the effectiveness of the combinative pretreatment methods.
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•The pretreatment efficiency of SFUS was higher than FFUS.•Recommended conditions for SFUS + DES were 40 kHz, 60 min, ChCl-LA, 120 °C, 3 h.•The SFUS + DES pretreatment resulted in ...85.62% LRR of SCB.•After SFUS + DES pretreatment, enzymatic hydrolysis of SCB yielded 86.76% glucose.•The hydrogen bonding of DES Cl- and lignin was responsible for lignin removal.
Sugarcane bagasse (SCB) is an abundant agricultural waste in China and the conversion of the waste into plethora of useful resources is very vital. To achieve this, fractionation of the waste is highly important in the biomass biorefinery. The present study aims at investigating the synergistic role of deep eutectic solvents (DES) with sweeping frequency ultrasound (SFUS) and fixed frequency ultrasound (FFUS) in the fractionation of SCB to enhance the enzymatic saccharification process. Therefore, the effects of ultrasound (US) and DES conditions on the pretreatment efficiency were investigated. Under optimum SCB pretreatment conditions, FFUS (40 kHz, 60 min) + DES (choline chloride (ChCl)-lactic acid (LA), 120 °C, 3 h) and SFUS (40 kHz, 60 min) + DES (ChCl-LA, 120 °C, 3 h), the lignin removal rates were 80.13 and 85.62%, respectively. The hemicellulose removal rates were 78.08 and 90.46%, respectively; and the contents of glucose, xylose and arabinose in the liquid fractions after FFUS + DES pretreatment were 7.07, 17.95 and 3.01%, respectively. However, the yield of glucose, xylose, and cellobiose after enzymatic hydrolysis of the SFUS + DES pretreated SCB were 86.76, 38.68, and 20.76%. Analytical studies revealed that the SFUS + DES pretreatment can effectively destroy the ultrastructure of SCB and reduce the crystallinity of cellulose. Furthermore, the mechanism of pretreatment with SFUS + DES was proposed, which confirmed the excellent performance of SFUS + DES. Thus, the application of SFUS + DES pretreatment was able to improve the removal of lignin and hemicellulose from SCBs.
Graphical illustration of the biomass conversion and its stability performance for the as-prepared Mo2C/C-800°Celectrocatalyst.
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•Fabrication of biomass-derived Mo2C/C electrocatalysts ...for HER application.•Mo2C/C displayed excellent HER performances in 1.0 M KOH medium.•Mo2C/C is characterized by large surface area, pore size and fast electron transfer.•Mo2C/C displayed low geometrical overpotential and long-term durability.•Mo2C/C synergistically enhanced catalytic performances.
The development of novel, efficient, durable and cheap electrocatalysts for hydrogen evolution reaction (HER) by electrochemical water-splitting is pivotal to solving the persisting energy problem related to hydrogen utilization as a renewable energy. Thus, Pt-like materials that are efficient, stable and cheap must be fabricated to overcome the commercial challenges facing electrocatalysts. Herein, biomass derived Mo2C/C electrocatalysts based on watermelon peels were fabricated for HER application through a simplistic two step approach and easy pyrolysis procedure. Benefiting from the excellent HER performances, abundant mass transfer of electrons, large surface areas and unique pore sizes of the fabricated Mo2C/C electrocatalysts, Mo2C/C-800 °C required geometrical overpotential of 133 mV to deliver a current density of 10 mAcm-2 in 1.0 M of KOH solution; and further displayed long-term durability process for 300 h. This study therefore introduced a novel approach to designing excellent electrocatalysts from biomass waste for HER application.
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