Pulsed Ultrasound-assisted Extraction Research Articles

Green Extraction of Pectin from Sugar Beet Flakes and Its Application in Hydrogels and Cryogels.

Sugar beet flakes, a by-product of the sugar industry, were used as a source for pectin extraction that was performed using conventional citric acid extraction (CE) and two non-conventional extraction techniques-microwave-assisted extraction (MAE) and pulsed ultrasound-assisted extraction (PUAE). The influence of extraction conditions was studied for each technique based on pectin yield and galacturonic acid content, and spectroscopic, chromatographic and colorimetric methods were used for pectin characterization. Better results for pectin yield were achieved through CE (20.80%), while higher galacturonic acid content was measured in pectin extracted using PUAE (88.53 g/100 g). Pectin extracted using PUAE also presented a higher degree of methylation and acetylation. A significant increase in the molecular weight of pectin was observed for the PUAE process (7.40 × 105 g/mol) by comparison with conventional extraction (1.18 × 105 g/mol). Hydrogels and cryogels prepared with pectin from sugar beet flakes also showed differences in physicochemical parameters determined by the method of pectin extraction. Hydrogels had higher bulk density values irrespective of the pectin extraction method, and overall lower values of the textural parameters. Cryogels prepared with pectin from CE showed higher values of the textural parameters of hardness, adhesiveness, cohesiveness, gumminess and chewiness, while gels obtained with pectin from MAE and PUAE had higher thermal stability. The results of this study prove that sugar beet flakes can be considered a potential source for pectin production, and the extracted pectin is suitable for obtaining hydrogels and cryogels with physicochemical parameters comparable to the commercial citrus and apple pectin available on the market.

Assessing the Efficiency of Antimicrobial Plant Extracts from Artemisia afra and Eucalyptus globulus as Coatings for Textiles.

This study aimed to assess the antimicrobial activities of plant extracts from Artemisia afra and Eucalyptus globulus when used as coatings for textiles. A pulsed ultrasound-assisted extraction method (PUAE) was employed to obtain methanolic and hexanoic extracts from both plants. Eucalyptus globulus methanol extraction exhibited the highest yield at 22.76% (±0.61%), while Artemisia afra demonstrated lower yields. Phytochemical screening identified various secondary metabolites in the extracts, including phenols, quinones, and steroids. Antimicrobial tests against Staphylococcus aureus and Escherichia coli revealed varying degrees of susceptibility, with Eucalyptus globulus hexanoic extracts showing the highest activity against Staphylococcus aureus at an average percentage growth of 18.74% (±0.26%). Minimum inhibitory concentration (MIC) values were determined for the extracts, but complete inhibition did not occur at concentrations below 500 μg/mL. The extracts exhibited varying effects on Staphylococcus aureus and Escherichia coli growth, with some extracts promoting bacterial growth. Coating textiles with Eucalyptus globulus methanolic extracts demonstrated antibacterial activity against Staphylococcus aureus with the highest zone of inhibition observed in cotton-coated samples (258.4 mm2). Polyester-coated samples exhibited smaller inhibition zones, with the lowest observed in Eucalyptus globulus methanolic extract coating (65.97 mm2). Scanning electron microscope (SEM) analysis revealed visible surface morphology changes in coated fabrics, depicting fine, cluster, lumpy, flaky, and fragment-like morphologies. Laundering effects on coated fabrics were investigated, showing a significant decrease in antimicrobial activity after washing. Fourier-transform infrared spectroscopy (FTIR) identified functional groups in the extracts associated with antimicrobial properties. The complexity of the bioactive compounds suggests potential antimicrobial efficacy, resting on factors such as geographical location, climate, and extraction methods. Notwithstanding the limitations, this study contributes valuable insights into the use of plant extracts as antimicrobial coatings for textiles.

Characterization of pectin extracted from pomelo peel using pulsed ultrasound assisted extraction and acidic hot water extraction process

In the present study, the characteristic properties namely XRD, FTIR, DSC, TGA and FESEM analyses of pectin extracted from pomelo fruit peel using pulsed ultrasound assisted extracted (PUUAE) were compared with those of pectin obtained with the conventional acidic hot water extraction (AHWE) process. The pectin extracted from PUUAE process has been analysed to possess better properties in comparison with the pectin obtained from the AHWE process. Pectin obtained from these two methods had been of high methoxyl pectin with almost similar structure. XRD analysis confirmed that AHWE based pectin possessed lower crystallinity than the PUUAE based pectin. The XRD spectra of PUUAE pectin affirmed sharper and stronger peaks than those of the AHWE based pectin and especially at 18.33° and 29.04° Further, the FTIR study revealed stronger absorption areas for PUUAE based pectin than those pertinent in the AHWE based pectin. This inferred that the pectin extracted with PUUAE had higher degree of esterification than that obtained with the AHWE process. Moreover, the DSC and TGA analyses indicated that PUUAE pectin had higher thermal stability in comparison to AHWE based pectin. The exothermic transition for the PUUAE based pectin was found to occur at higher temperature (245.7 °C) in comparison to the AHWE based pectin sample (239 °C). The TGA study conveyed double-stage decomposition for the PUUAE pectin sample (two DTGA peak temperatures (first at 230 °C and the second at 317 °C)) in comparison to the data obtained for the AHWE based pectin sample (a single peak only appears at 182 °C). The FESEM study affirmed a smoother surface with more structural integrity for PUUAE based pectin than that pertinent in the AHWE pectin sample. Therefore, the obtained characteristics can be inferred to the view that the PUUAE process is effective for the production of high quality pectin from pomelo peel (PP) for relevant functional applications.

Comparisons of pulsed ultrasound-assisted and hot-acid extraction methods for pectin extraction under dual acid mixtures from onion (Allium cepa L.) waste.

The aim of this study is to compare the physicochemical properties and yields of pectins extracted from onion waste under hot acid (HAE) and pulsed ultrasound-assisted extraction (PUAE) methods using different organic-inorganic acids, their mixtures, and pure water. The extraction temperature for experiments carried out under HAE was kept at 90°C for 90 min, whereas PUAE experiments were accomplished at RT in 15 min. In general, HAE gave better pectin yields compared with PUAE due to the significance of the increasing extraction temperature for the release of pectin from the plant matrix. While the maximum pectin yield from onion waste was 16.22% for HAE, the highest yield for PUAE was 9.83%. PUAE provides less time- and energy-consuming extraction of pectin within 15 min and thus seems to be more economic compared with the HAE. According to the physicochemical properties (equivalent weight (EW), degree of esterification (DE), methoxyl (MeO), and galacturonic acid (Gal-A) contents) of obtained pectins, extracted pectins were mostly high methoxy pectin. While the DE and MeO values of pectins extracted in organic acid conditions under HAE were higher, these values were found to be higher for pectins extracted in inorganic acids under PUAE. For acid mixtures, the DE and MeO values of pectins under HAE were mostly found to be lower than those under PUAE. Sequential PUAE and HAE methods for the extraction of pectin from onion waste were also found to be useful in terms of obtaining higher yields and better physicochemical properties. The highest pectin yield was 20.32% for the sequential PUAE and HAE methods. FT-IR analyses of the extracted pectins by both HAE and PUAE methods showed similar vibration bands compared with those of commercial citrus pectin.

Effect of the Shape of Ultrasonic Vessels on the Chemical Properties of Extracts from the Fruit of Sorbus aucuparia

The goal of this study was to analyse the effect of sonoreactor dimensions on the effectiveness of the ultrasound-assisted extraction (UAE) of bioactive substances from rowan (Sorbus aucuparia L.). Sonication was carried out with a VC750 Sonics processor at the following amplitudes of ultrasound: 12, 24, and 36 µm. The frequency of the ultrasound was 20 kHz. Extraction was conducted in a 2 s on–4 s off pulse system. The total phenolic content and antioxidant activity were determined using a spectrophotometric method. The pH value of the extracts was measured using a combined pH metric electrode, type EPS-1 (Elmetron). Response surface methodology (RSM) was used to optimise the investigated variables. On the basis of the developed model, the following variable values were obtained: TPC—12.48 gallic acid equivalent (GAE)/g, 2,2′-azino-bis-(3-ethylbenzothiazoline-6-sulfonic acid) (ABTS) values—126.54 μmol Trolox (TE)/g, 2,2-diphenyl-1-picryl-hydrazyl-hydrate (DPPH) values—79.58 μmol TE/g, ferric reducing antioxidant power assay (FRAP) values—120.65 μmol TE/g for an extraction vessel with a diameter of 35 mm and TPC—11.68 mg GAE/g, ABTS values—120.49 μmol TE/g, DPPH values—75.90 μmol TE/g, FRAP values—155.54 μmol TE/g for an extraction vessel with a diameter of 25 mm. Significant influences of time, ultrasound amplitude, and alcohol concentration on the course of the extraction process in the tested extraction vessels were found. The optimum extraction conditions for an extraction vessel with a diameter of 35 mm were obtained for an ethyl alcohol concentration of about 60%, and for an extraction vessel with a diameter of 25 mm the optimum conditions were for an alcohol concentration in the range of 30–50%. A very strong positive linear correlation was found between the concentration of ethyl alcohol and the pH value of the obtained extracts for both extraction reactors. The developed models of pulsed ultrasound-assisted extraction were characterised by a good predictive capacity (77.49–91.39%) and can be used for obtaining polyphenols from rowan.

Energy Aspects of Flavonoid Extraction from Rowanberry Fruits Using Pulsed Ultrasound-Assisted Extraction

The aim of the study was to analyze the influence of the dimensions of extraction cells on the energy aspects and extraction efficiency of flavonoids from rowanberry fruits (S. aucuparia L.). The total flavonoid content was determined using the spectrophotometric method. Response surface methodology (RSM) was used to optimize the variables under investigation. The flavonoid content in the obtained extracts ranged from 0.17 to 0.66 mg QE/g dry matter for cells with a diameter of 3.5 cm, and from 0.19 to 0.7 mg QE/g dry matter for cells with a diameter of 2.5 cm, depending on the other experimental conditions. The energy consumption during extraction in the 3.5 cm diameter cell ranged from 0.451 kJ to 26.120 kJ, while for the 2.5 cm diameter cell, it ranged from 0.637 kJ to 25.677 kJ. The unit energy consumption for the 3.5 cm diameter cell ranged from 1.47 kJ/mg QE/g to 48.92 kJ/mg QE/g. For the 2.5 cm diameter cell, these values ranged from 2.17 kJ/mg QE/g to 40.64 kJ/mg QE/g. Significant effects of the dimensions of the extraction cells on flavonoid yield and unit energy consumption were observed, while there was no impact on electricity consumption. The dimensions of the extraction cells were also found to influence the form of the obtained empirical models.

Application of Response Surface Method in Pulsed Ultrasound-Assisted Extraction of Complex Plant Materials—A Case Study on Cannabis sativa L.

The purpose of this study was to optimize the effect of particle size, time and ultrasonic intensity on the extraction of phenolic compounds and energy efficiency. Sonication was performed with a VC750 Sonics processor at the following amplitudes: 30, 50 and 70%, which corresponds to the ultrasonic intensity, respectively: 1.6; 5.1 and 8.6 W∙cm−2. The frequency of ultrasound was 20 kHz. Extraction was carried out in a 5 s on–10 s off pulse system. The content of polyphenols and their antioxidant activity were assayed by the spectrophotometric method. Response surface methodology (RMS) was used to optimize the investigated variables. On the basis of the developed model, the highest polyphenols yield was obtained under the following extraction conditions (particle size 0.65 mm, extraction time 13.14 min, ultrasound intensity 6.92 W∙cm−2, which resulted in a maximum value of 15.24 mg GAE∙g−1 dry matter of hemp. Taking into account the lowest unit energy consumption, the best conditions were obtained for particle size of approx. 0.5 mm, extraction time 7.7 min, and ultrasound intensity 1.8 W∙cm−2, which resulted in a phenolic yield of 10.14 mg GAE∙g−1 dry matter of hemp. The best agreement between values of optimization variables within investigated criteria was obtained for the variable particle size. The developed models of pulsed ultrasound-assisted extraction can be used for obtaining polyphenols from Cannabis sativa L. at low unit energy consumption.

Continuous and pulsed ultrasound-assisted extraction of pectin from pomelo fruit peel using citric acid

Continuous and pulsed ultrasound-assisted extraction of pectin from pomelo fruit peel using citric acid

Structural, functional and physicochemical properties of pectin from grape pomace as affected by different extraction techniques

Pectin from grape pomace (Vitis vinifera var. Fetească Neagră and Vitis vinifera var. Rară Neagră) was extracted by using different extraction techniques (conventional, microwave-assisted and pulsed ultrasound-assisted extraction). Microwave-assisted extraction showed highest yield (11.2 %) for Rară Neagră pectin, while conventional extraction presented highest yield (9.9 %) for Fetească Neagră pectin. The yield was directly correlated with the galacturonic acid content, degree of esterification, molecular weight and functional features (water-holding, oil-holding and water-swelling capacity, emulsifying properties and rheological behavior of pectin emulsions). In addition, the FT-IR, morphological structure, thermal analysis and emulsion properties of obtained pectin samples from different extraction techniques revealed dissimilar results by comparing with commercial pectin.

Pulsed ultrasound-assisted extraction followed by purification with SBA-15 for the control of opium alkaloids in biscuits and sponge cakes

Food products containing poppy seeds are increasingly consumed. These seeds may be contaminated with opium alkaloids (OAs) from the latex of the plant (Papaver somniferum L.), which may present a health hazard to the consumer. Therefore, the aim of this work was to develop an efficient, fast and environmentally friendly methodology to control OAs in biscuits and sponge cake products by analysis with liquid chromatography coupled to a triple quadrupole tandem mass detector (HPLC-MS/MS). For this purpose, the ultrasound-assisted extraction (UAE) step was optimised using a 5-variable full factorial design at two levels, obtaining lower solvent volume and time than with other classical methods. Then, a solid phase extraction (SPE) was used to remove matrix effects. A commercial material (HLB) and two silica synthesised materials (HMS and SBA-15) were evaluated and optimised, selecting SBA-15 (50 mg). Finally, the method was validated and applied to real samples, showing morphine concentrations in 5 of 7 products but below the maximum permitted limit.

Optimizing Pulsed Ultrasound-Assisted Extraction of Antioxidants from Linden and Quantification by HPLC–PDA

Optimizing Pulsed Ultrasound-Assisted Extraction of Antioxidants from Linden and Quantification by HPLC–PDA

Characterization of Pectin from Grape Pomace: A Comparison of Conventional and Pulsed Ultrasound-Assisted Extraction Techniques

The yield, physicochemical and rheological parameters of grape pomace pectin (Fetească Neagră and Rară Neagră) obtained by conventional extraction (CE) were compared to those acquired by pulsed ultrasound-assisted extraction (PUAE). Extraction temperature (70–90 °C), pH (1–3) and time (1–3 h) were considered as independent variables for CE, while amplitude (20–100%), pH (1–3) and time (20–60 min) for PUAE. The optimal conditions for maximum yield and physicochemical parameters of pectin samples extracted by CE were temperature of 90 °C, pH 1.9 for 164 min (9.96% yield, 79.91 g/100 g of galacturonic acid (GalA) content, 81.28% of degree of esterification (DE) and 5.52 × 104 g/mol of molecular weight (Mw) for Fetească Neagră (FN) pectin; 11.08% yield, 80.05 g/100 g of GalA content, 80.86% of DE and 5.59 × 104 g/mol of Mw for Rară Neagră (RN) pectin), while for PUAE they were amplitude of 100%, pH 1.8 for 60 min (8.83% yield, 80.24 g/100 g of GalA content, 81.07% of DE and 4.19 × 104 g/mol of Mw for FN pectin; 8.94% yield, 78.64 g/100 g of GalA content, 80.04% of DE and 4.23 × 104 g/mol of Mw for RN pectin). The yield and physicochemical parameters of CE pectin were higher than PUAE pectin. The FT-IR spectra of pectin samples revealed the occurrence of polysaccharide compound, while rheology characteristics confirming its application in different food products.

Continuous ultrasound and pulsed ultrasound: Selective extraction tools to obtain enriched antioxidants extracts from cocoa beans (Theobroma cacao L.)

In this study, the effect of continuous assisted extraction (CUAE) and pulsed ultrasound assisted extraction (PUAE) of phenolic compounds from cocoa beans was evaluated. Frequency (25/45 kHz) and extraction time (15/30 min) were varied. Phenolic acids were identified as catechin-(+), epicatechin-(+), procyanidin B1 and procyanidin B2 were quantified on each extract by HPLC-DAD. Then, total phenolic content (TPC), total flavonoids content (TFC), flavan-3-ols, non-flavonoids content (NF) and proanthocyanidins (PAC) were determined. The experimental findings indicated the highest extraction yields of TPC and flavonoids subclasses when prolonged PUAE was used. Additionally, an increase of 282% in epicatechin yield was obtained compared with CUAE. However, the prolonged use of continuous sonication increased the non-flavonoids extraction yield in 23% compared with pulsed sonication. The scavenging and iron chelating activity depended on the chemical composition of each extract and was not correlated directly to TPC.

Pulsed ultrasound-assisted extraction of bioactive compounds from papaya pulp and papaya peel using response surface methodology: Optimization and comparison with hot water extraction

This article focusses on the pulsed ultrasound-assisted extraction (PUSAE) of nutritionally significant bioactive components from papaya pulp (PP) and papaya peel (PPEE) system. The effects of independent process variables such as sonication time (5 – 20 min), extraction temperature (40–70 °C), and solid to liquid ratio (loading ratio) (0.2–0.5 g/mL) on the yield of response variables such as total flavonoids (TF), total phenols (TP), antioxidant activity (AOA), and vitamin C (VC) from papaya pulp (PP) and papaya peel (PPEE) system were investigated using a face centred design (FCD) of the response surface methodology (RSM). For comparative analysis, findings from the hot water extraction process (HWEX) were compared with the optimal results of this study. According to the findings, the bath type pulsed ultrasound-aided system yielded 80.87–169.16 mg GAE/g total phenols (TP), 31.29–92.9% antioxidant activity (AOA), and 28.52–164.94 mg/100 g vitamin C (VC) for the PP case and 97.46–145.44 GAE/g sample total phenols (TP), 97.36–292.2 mg QE/g total flavonoids (TF), and 46.51–89.17% antioxidant activity (AOA) for the PPEE case. The investigations confirmed that the PUSAE technique outperformed the HWEX (105 mg GAE/g sample total phenols (TP), 89.4 mg/100 g vitamin C (VC), and 76.50% antioxidant activity (AOA) for PP case and 88.5 mg GAE/g sample total phenols (TP), 145 mg QE/g vitamin C (VC), and 71.5% antioxidant activity (AOA) for PPEE case) quite effectively for both PP and PPEE systems. Furthermore, the study revealed that the PP extract contained the highest level of bioactives when compared to the PPEE system. These findings suggest that the pulsed mode ultra-sonication process has more potential than traditional extraction methods (such as soxhlet extraction, maceration, percolation etc.) for producing papaya pulp and papaya peel aqueous extract for medicinal and functional food applications.

Optimization of the Ultrasound-Assisted Extraction of Bioactive Compounds from Cannabis sativa L. Leaves and Inflorescences Using Response Surface Methodology

This study investigated the effects of particle size and ultrasonic parameters on the yields of bioactive compounds extracted from the leaves and inflorescences of hemp. The total flavonoid and anthocyanin contents were determined using the spectrophotometric method. The response surface methodology (RMS) was employed to optimize the yield of bioactive substances. On the basis of the developed model, the highest flavonoid yield was obtained under the following extraction conditions: particle size, 0.59 mm; extraction time, 10.71 min; ultrasound intensity, 7.13 W∙cm−2; extraction yield, 9.28 mg QE∙g−1; determination coefficient, R2 = 0.97. The optimal conditions for extracting anthocyanins were as follows: particle size, 0.25 mm; extraction time, 15 min; ultrasound intensity, 8.60 W∙cm−2; extraction efficiency, 20.27 mg Cy-GE∙100 g−1; determination coefficient, R2 = 0.87. This study helped confirm the importance of pulsed ultrasound-assisted extraction in obtaining bioactive compounds from hemp.

Effect of the duty cycle of the ultrasonic processor on the efficiency of extraction of phenolic compounds from Sorbus intermedia

This paper studies the effect of different ultrasonic parameters on the yield of extraction and antioxidant activity of selected phenolic compounds from Sorbus intermedia berries. The sonication was carried out in two modes: continuous and pulse. In the pulse mode, the samples were sonicated with the following processor settings: 1 s on–2 s off. The effective ultrasonic processor times were 5, 10, and 15 min, and the total extraction times were 15, 30, and 45 min. The results showed that the duty cycle significantly affected the antioxidant activity of the extracts and the yield of chlorogenic acid, rutin, and total flavonoids. Compared to the continuous mode, the pulse ultrasound increased the extraction yield of rutin by 5–27%, chlorogenic acid by 12–29%, and total flavonoids by 8–42%. The effect of the duty cycle on the extraction yield was dependent on the intensity and duration of the ultrasound treatment. The mechanism of the influence of the pulsed ultrasound field on the extraction process has been elucidated. This research clearly demonstrated the superiority of pulsed ultrasound-assisted extraction for production of antioxidants from Sorbus intermedia berries.

Efficacy of ultrasound-assisted extraction of bioactive constituents from Psidium guajava leaves

Targeting the sensitivity of process parameters in due course of the optimal ultrasound assisted extraction of bioactives from guava leaves. The purpose of the conducted investigations was to scope and optimize the efficacy of ultrasound assisted extraction in conjunction with hot water extraction. Addressing the criticality of loading ratio, low temperature drying as pre-treatment step and consideration of all desired responses, the article addresses the normal and pulsed ultrasound assisted extraction of bioactive constituents from guava leaf powder. The experimental methodology involved face centered design (FCD) based response surface methodology (RSM). The investigations affirmed that the normal ultrasound assisted extraction process exhibited 15.5 – 68.8 mg GAE/g total polyphenolic content (TPC), 50.1 – 80.3 % antioxidant activity (AA), 5.7 – 25.7 mg/100g vitamin C (VITC) content and 44.7 – 289.77 mg QE/g total flavonoids content (TFC) for a variation in the degrees of freedom as 0.02 – 0.2 g/mL loading ratio, 5 – 20 min extraction time and 40 – 70 °C extraction temperature. Pertinent observations have been documented in terms of comparative criticality of the degrees of freedom, best fit model and efficacy of the pulsed mode.

Healthy Properties of a New Formulation of Pomegranate-Peel Extract in Mice Suffering from Experimental Autoimmune Encephalomyelitis.

A new formulation of a pomegranate-peel extract (PEm) obtained by PUAE (Pulsed Ultrasound-Assisted Extraction) and titrated in both ellagic acid (EA) and punicalagin is proposed, characterized and then analyzed for potential health properties in mice suffering from the experimental autoimmune encephalomyelitis (EAE). PEm effects were compared to those elicited by a formulation containing EA (EAm). Control and EAE mice were chronically administered EAm and Pem dissolved in the drinking water, starting from the day 10 post-immunization (d.p.i.), with a “therapeutic” protocol to deliver daily 50 mg/kg of EA. Treated EAE mice did not limit their daily access to the beverage, nor did they show changes in body weight, but they displayed a significant amelioration of “in vivo” clinical symptoms. “Ex vivo” histochemical analysis showed that spinal-cord demyelination and inflammation in PEm and EAm-treated EAE mice at 23 ± 1 d.p.i. were comparable to those in the untreated EAE animals, while microglia activation (measured as Ionized Calcium Binding Adaptor 1, Iba1 staining) and astrocytosis (quantified as glial fibrillar acid protein, GFAP immunopositivity) significantly recovered, particularly in the gray matter. EAm and PEm displayed comparable efficiencies in controlling the spinal pathological cellular hallmarks in EAE mice, and this would support their delivery as dietary supplementation in patients suffering from multiple sclerosis (MS).

Pulsed ultrasound assisted extraction of protein from defatted Bitter melon seeds (Momardica charantia L.) meal: Kinetics and quality measurements

Bitter melon seeds (BMS) are a one such by-product discarded from Bitter gourd processing industries. In this study our aim was extraction of protein from defatted Bitter melon seeds meal using pulsed ultrasound assisted extraction (PUSAE). Effect of ultrasound power level (300, 375 and 450W) and time (2.50, 5.00, 7.50, 10.00, 12.50, 15.00, 17.50 and 20.0 min) on protein yield and quality characteristics were evaluated. Peleg's model was used to describe the kinetics of extraction process. The highest yield of 23.79% at 300W, 31.05% at 375W and 28.93% at 450W was obtained. At a higher ultrasound power levels, the yield was slightly reduced due to protein aggregation formation. Enhancement in water holding capacity, solubility, emulsion capacity, emulsion stability and least gelation capacity in PUSAE protein samples were observed compared to conventional extracted Bitter melon seed protein. The FTIR absorption spectra reveal the characteristics changes in secondary structure of protein mainly in the region of α-helix, β-sheet, β-turn and random coil. The present study indicates that PUSAE increases the protein yield and improves the techno-functional characteristics of Bitter melon seed protein.

Effect of pulsed ultrasound assisted extraction and aqueous acetone mixture on total hydrolysable tannins from pomegranate peel

Pomegranate peels are disposed of as waste even though it is an eminent source of total hydrolysable tannins (THT) and possesses a great worth for recycling. The present study was carried out with the hypothesis that pulsed system ultrasound-assisted extraction (PSUAE) technique optimization would aid in retaining high extract yield and THT recovery yield from pomegranate peel extract (PPE) with enhanced antioxidant potential. The extraction was performed at various conditions regarding solvent concentration (30–90% of acetone), solvent-feed ratio (10–30 mL/g), extraction time (10–20 min), and ultrasound amplitude (40–80%) for maximum extract yield, THT and antioxidant activity (AA). To model and optimize the process conditions tools namely response surface methodology (RSM) and artificial neural network (ANN) were applied. For solvent concentration, solvent-feed ratio, extraction time, and amplitude the optimal conditions attained with aid of RSM and ANN were: 56%, 26.5 mL/g, 15 min, 55%, and 45%, 23 mL/g, 15 min, 50% respectively. The extract yield and THT content determined with RSM and ANN optimized values were 51.2%, 86.4 mg TAE/g, and 62%, 98.1 mg TAE/g, respectively. The mean square error value displayed the minimum and R2 exhibited maximum value in case of ANN compared to RSM model. PSUAE significantly augmented the AA of PPE to 77.2 ± 0.50% compared to 49.7 ± 0.35% of conventional extraction. FTIR and HPLC analysis established that PPE produced from PSUAE contains a significant amount of THT compounds (gallic acid and tannic acid derivative). SEM elucidated that the sonication effect resulted in peel cell wall disruptions ensuing in elevated extraction of THT. Therefore, this pulsed mode of ultrasound extraction could be regarded as an easy, cost-effective, and competent technique for the extraction of preferred natural THT from pomegranate peels that possess high prospective to be applied in food and nutraceutical formulations.