Microwave and pulsed electric field assisted extractions of polyphenols from defatted canola seed cake

The incorporation of microwave and pulsed electric field (PEF) technologies in optimising the extraction of polyphenols from defatted canola seed cake was determined by Box‐Behnken response surface methodology, using three parameters of microwave treatment (power, time and liquid: solid (L:S) ratio) and four parameters of PEF (ethanol concentration, time, frequency and voltage). After microwave and PEF pretreatments, the polyphenols of defatted canola seed cake were extracted by ultrasound treatment under fixed variables (200 W of ultrasonic power, 70 °C of water bath and 20 min of extraction time). The measured responses were total phenolics, total flavonoids, the DPPH˙ scavenging activity and ferric reducing antioxidant power (FRAP). The maximum yields of all responses were achieved under optimum conditions of microwave processing (5 min, L:S ratio of 6.0 and 633.3 W) and PEF‐assisted extraction (30 V, 30 Hz, 10% ethanol concentration and 10 s).     

Screening the Experimental Domain for the Microwave-Assisted Extraction of Secoisolariciresinol Diglucoside from Flaxseed Prior to Optimization Procedures

This paper presents the first part of a study that aims at developing an optimized microwave-assisted method for extracting the lignan secoisolariciresinol diglucoside from defatted flaxseed meal. Two-level fractional factorial designs were used for screening the following factors: the microwave power level (30–360 W), the time of residence in the microwave cavity (1–25 min), the concentration of NaOH (0.25–1 M), and the mode of microwave power application (power on 30 and 60 s/min). The experimental domain had to be adjusted after each screening in order to focus the future optimization study within the factors' ranges likely to contain the optimal extraction conditions.     

Effect of supercritical CO2 extraction process parameters on oil yield and pigment content from by‐product hemp cake

This research gives an insight into the possibility of exploiting the one of the food industry's by‐products – pressed hemp cake. The complete recovery of oil from pressed hemp cake was achieved. Residual oil that remained in cake after pressing was extracted with supercritical CO₂ by applying different process parameters. Optimal extraction conditions were determined using response surface methodology. Total pigment contents of the oils obtained were determined. Extraction pressure had the most significant influence on yield and pigment content of extracted hemp cake oil. Depending on the pressure, the chlorophyll a content ranged from 101.11 to 378.28 mg kg^?1 and chlorophyll b from 65.14 to 189.78 mg kg^?1, while total carotene content was in the range from 33.58 to 132.67 mg kg^?1. The remaining oil in pressed hemp cake after supercritical CO₂ extraction was determined to be 0.56 ± 0.08% and the defatted cake was rich in proteins and fibre.     

Optimizing the Tyrosinase Inhibitory and Antioxidant Activity of Mango Seed Kernels with a Response Surface Methodology

This study describes the optimization of polyphenol extraction from mango seed kernels by using response surface methodology (RSM). In the solid-to-liquid selection, the extraction yield, total phenolic content (TPC), antioxidant activity, and tyrosinase inhibitory activity are all significantly increased with a decrease in the solid-to-liquid ratio (P?<?0.05). Between the Nam-Dok-Mai kernel (NDK) and the Tong-Dam kernel (TDK), the TDK was chosen for RSM with a fixed ratio of 1:30 solid-to-liquid. The variables in the independent processing were the concentrations of ethanol, the temperature, and the time applied to RSM. Ethanol concentration, temperature, and duration had significant individual and interactive effects on phenolic yield and antioxidant activities (P?<?0.05). The optimized condition that maximized the extraction yields, TPC, and antioxidant activities from TDK was an ethanol concentration of 62 %, a temperature of 63 °C, and a duration of 150 min. The obtained and validated optimized model could be used to describe the effect of these variables on the extraction of phenolic compounds from mango seed kernels.     

Sequential Microwave-Ultrasound-Assisted Extraction for Isolation of Piperine from Black Pepper (<Emphasis Type="Italic">Piper nigrum</Emphasis> L.)

Piperine is the natural bioactive component of black pepper (Piper nigrum L.) with several astounding therapeutic properties. In this study, sequential microwave-ultrasound-assisted extraction approach was used for isolation of piperine from black pepper. The effect of various factors such as extraction solvent, particle size of pepper, solvent to solid ratio, microwave power and time and ultrasound temperature and time on the extraction yield of piperine was considered. The maximum extraction yield was 46.6 mg piperine/g pepper which was obtained using ethanol as solvent at the particle size of 0.15 mm, solvent to solid ratio of 20:1, microwave power of 100 W for 1 min, and ultrasound temperature of 50 ^° C for 30 min. This extraction yield was higher than those obtained by Soxhlet (39.1 mg/g), microwave-assisted (38.8 mg/g) and ultrasound-assisted (37.0 mg/g) extractions. The purity of the extracted piperine was 81.4% as determined by HPLC analysis. The FTIR and UV-vis analyses confirmed that the structure of piperine remained intact after extraction and purification which is very important for medicinal applications.     

Design of Sonotrode Ultrasound-Assisted Extraction of Phenolic Compounds from <Emphasis Type="Italic">Psidium guajava</Emphasis> L. Leaves

Psidium guajava L. has gained a special attention as health plant due to the presence of phenolic compounds. Box-Behnken design (BBD) has been applied for the extraction of target compounds from guava leaves via sonotrode ultrasound-assisted extraction (UAE). Different extraction times (5, 30, and 55 min), ratios of ethanol/water (50, 75, and 100% (v/v)), and ultrasound (US) power (80, 240, and 400 W) were tested to find their effect on the sum of phenolic compound (SPC), flavonols and flavan-3-ols via HPLC-ESI-QqQ-MS, and antioxidant activity (DPPH and TEAC assays). The best process conditions were as follows: 40 min, 60% ethanol/water (v/v), and 200 W. Established method has been used to extract phenolic compounds in two guava leaves varieties (pyrifera and pomifera). Pyrifera var. showed greater values of the SPC via HPLC-ESI-QqQ-MS (49.7 mg/g leaf dry weight (d.w.)), flavonols (12.51 mg/g d.w.), flavan-3-ols (7.20 mg/g d.w.), individual phenolic compounds, and antioxidant activity (8970 ± 5 and 465 ± 6 μmol Trolox/g leaf d.w, respectively) than pomifera var. Conventional extraction showed lower amounts of phenolic compounds (7.81 ± 0.03 and 4.64 ± 0.01 mg/g leaf d.w. for flavonols and flavan-3ols, respectively) in comparison to the ultrasound-assisted ones.     

Influence of Microwave Treatment of Rapeseed on Minor Components Content and Oxidative Stability of Oil

Rapeseeds were adjusted to moisture contents of 9, 11, 13, and 15 % and treated with microwaves under 800 W for 0, 1, 2, 3, 4, 5, 6, and 7 min at a frequency of 2,450 MHz and oil was extracted with a press to investigate possibility of enhancing oil extraction yield by press, minor component content, and oxidative stability of the pressed oil. The results indicated that microwave pretreatment of rapeseed could increase the oil extraction yield, and both microwave time and initial moisture content of rapeseed had significant effects on the oil extraction yield (p?<?0.001). Total tocopherol content in the oil extracted by press first increased and then decreased depending on the period of microwave radiation (p?<?0.001), and the initial moisture content had no significant effect on the tocopherol content (p?>?0.05). Phytosterol and polyphenol contents increased with increasing microwave time and with decreasing initial moisture content of rapeseeds (p?<?0.001). An F test revealed there were significant interactions between the effects of microwave time and initial moisture content on both polyphenol content and oil extraction yield. The oxidative stability of oil were improved with increasing microwave time and decreasing initial moisture content (p?<?0.001), and there were significant positive correlations with total polyphenol and phytosterol contents. Therefore, it is advisable to treat rapeseeds with low initial moisture content by microwaves prior to oil extraction by press because it results in a relatively good oil extraction yield by cold press, with a high amount of phenolic, tocopherol, and phytosterol. Microwave pretreatment had a positive effect on oxidative oil stability in comparison to the untreated oil.     

Effect of the defatting process,acid and alkali extraction on the physicochemical and functional properties of hemp,flax and canola seed cake protein isolates

The effect of the defatting process, acid and alkali extractions on the physicochemical and functional properties of hemp, flax and canola protein isolates was studied. The defatting process enriched the protein content from around 35 to 52–55 % in the defatted oilseed cakes. Further treatment with acid and alkali led to the highest enrichment (P < 0.05) in the protein content (>90 %). The defatting process produced the lightest (P < 0.05) colour compared to the parent oilseed cakes and the protein isolates. Alkali extraction produced protein isolates with the highest (P < 0.05) water holding capacity while the original oilseed cakes had the highest oil holding capacity. Acid and alkali extractions produced protein isolates with the highest emulsifying activity and emulsion stability. The alkaline soluble flax protein isolate and acid hemp protein isolate had the highest (P < 0.05) creaming stability and largest droplet size respectively. Amino acid profiles of protein isolates after acid and alkali extraction were improved, leading to a protein suitable for fortification in food products that meet human nutrition requirements.     

微波预处理火麻籽对其毛油δ9-四氢大麻酚含量及品质的影响

在火麻籽油的提取过程中,火麻籽中的毒性成分δ~9-四氢大麻酚易随油脂溶出,降低火麻籽油的品质。采用滚筒式微波翻炒设备对火麻籽进行热处理,旨在降低火麻籽油中的δ~9-四氢大麻酚含量,并对微波处理前后的火麻籽饼残油率及火麻籽毛油品质进行了分析。结果表明:在微波功率1 000 W、微波时间15 min的条件下,火麻籽毛油中的δ~9-四氢大麻酚含量由122.63 mg/kg降至57.33 mg/kg,氧化诱导时间由2.28 h升至3.02 h,生育酚含量由708.38 mg/kg升至716.88mg/kg,火麻籽饼残油率由14.36%降至9.98%。火麻籽毛油的酸值和过氧化值略有增加,脂肪酸组成及含量无显著变化。     

Simultaneous Determination of Antioxidants and Ultraviolet Absorbers by Ultra-Performance Liquid Chromatography in Food Simulants

An efficient analytical method for the quantitative determination of migration levels of antioxidants and UV absorbers in food contact materials by ultra-performance liquid chromatography has been developed. The analytical method showed good linearity, presenting regression coefficients (R ²?≥?0.9981) for all compounds. The limits of detection and quantification were between 0.03 and 0.32 mg L^?1 and between 0.08 and 1.06 mg L^?1 for 29 analytes, respectively. According to European Union Directive No. 10/2011, five food simulants were investigated: 3 % (w/v) acetic acid, 10 % (v/v) ethanol, 20 % (v/v) ethanol, 50 % (v/v) ethanol, and fatty food simulant (isooctane). Recoveries were in the range of 88.43?～?115.28 %, with relative standard deviations between 0.33?～?8.43 %. Migration levels of antioxidants and UV absorbers were determined. Irganox 1010, Irganox 1076, and Tinuvin 120 were found in the majority of the samples generally together with the phosphate Irgafos 168 and its oxidized product. These levels were lower than limits allowed by legislation.     

Optimization of Extraction Parameters of Total Phenolics from <Emphasis Type="Italic">Annona crassiflora</Emphasis> Mart. (Araticum) Fruits Using Response Surface Methodology

In this study, response surface methodology was used to optimize the extraction temperature (25–75 °C) and ethanol concentration (0–70 %, ethanol/water, v/v) to maximize the extraction of total phenolic compounds (TPC) from araticum pulp. The efficiency of the extraction process was monitored over time, and equilibrium conditions were reached between 60–90 min. A second-order polynomial model was adequately fit to the experimental data with an adjusted R ² of 0.9793 (p < 0.0001) showing that the model could efficiently predict the TPC content. Optimum extraction conditions were ethanol concentration of 46 % (v/v), extraction temperature of 75 °C and extraction time of 90 min. Under the optimum conditions, the araticum pulp showed high TPC content (4.67 g GAE/100 g dw) and also high antioxidant activity in the different assays used (46.56 μg/mL, 683.65 μmol TE/g and 1593.72 μmol TE/g for DPPH IC₅₀, TEAC and T-ORAC_FL, respectively). From our extraction procedure, we successfully recovered a significantly higher amount of TPC compared to other studies in the literature to date (1.5–22-fold higher). Furthermore, TPC and antioxidant activity were present in the fruit in levels that are difficult to find in other common fruits. These results expose a potential approach for improving human health through consumption of araticum fruit.     

Improving the Extraction of Juice and Anthocyanins from Blueberry Fruits and Their By-products by Application of Pulsed Electric Fields

Pulsed electric field (PEF) treatments (1–10 kJ/kg at 3 kV/cm) were applied before pressing of blueberry fruits to improve the yield and quality of expressed juice as well as the recovery of anthocyanins from blueberry by-products (press cake) via solid–liquid extraction. A PEF pre-treatment at 1 kJ/kg was sufficient to significantly increase the juice yield (by 32%) with respect to the untreated sample. Higher energy input (10 kJ/kg) was most favorable for the largest increment of anthocyanin content (55%) and antioxidant capacity (36 and 41%, determined by ferric reducing antioxidant power (FRAP) and 2,2-diphenyl-1-picrylhydrazyl hydrate (DPPH) assay, respectively) in juice. Extracts obtained from the press cake of PEF-treated blueberries at 10 kJ/kg possessed an anthocyanin content (75%) and antioxidant capacity (71 and 109%, determined by FRAP and DPPH assay, respectively) higher than that of the extracts obtained from non-treated berries press cake. HPLC analyses revealed the major classes of the detected anthocyanins as glycosides of delphinidin, cyanidin, petunidin, peonidin, and malvidin, and no significant degradation of individual anthocyanins due to PEF application was observed. The present PEF pre-treatment could be a promising approach to facilitate efficient extraction of juice and antioxidants especially anthocyanins from blueberry and their by-products.     

Optimization of Microwave-Assisted Extraction of Polyphenolic Compounds from <Emphasis Type="Italic">Ocimum basilicum</Emphasis> by Response Surface Methodology

Microwave-assisted extraction (MAE) was optimized by response surface methodology in order to enhance the extraction of polyphenols from basil (Ocimum basilicum L). Box–Behnken experimental design on three levels and three variables was used for optimization. Influence of ethanol concentration (50, 70, and 90%); microwave power (400, 600, and 800 W); and extraction time (15, 25, and 35 min) on each response were investigated. Experimental results were fitted to a second-order polynomial model, and multiple regression analysis and analysis of variance were used to evaluate model fitness and optimal conditions. Considering the maximum content of extracted total phenols, total flavonoids, and antioxidant activity, the optimal conditions for all investigated response were ethanol concentration of 50%, microwave power of 442 W, and extraction time of 15 min. Under the optimal conditions, obtained basil liquid extract contained 4.299 g gallic acid equivalents/100 g dry weight (DW) of total polyphenols, 0.849 g catechin equivalents/100 g DW of total flavonoids, and IC₅₀ and EC₅₀ values of 9.602 and 82.889 μg/mL, respectively. The development of simultaneous MAE procedure for extraction of total phenols, total flavonoids, and potential antioxidants from basil, represented valorization of basil as valuable source of bioactive compounds.     

Evaluating the Effectiveness of β-Carotene Extraction from Pulsed Electric Field-Treated Carrot Pomace Using Oil-in-Water Microemulsion

Thermodynamically stable microemulsions were used to extract β-carotene from pulsed electric field (PEF)-treated carrot pomace. In this study, a three-level Box–Behnken design was used to predict the effect of extraction time (10–110 min), extraction temperature (30–70 °C) and carrot/microemulsion ratio (1:30–1:90 w/w) on the β-carotene content, polydispersity index (PDI) and particle size of the microemulsions. The β-carotene extracted from PEF-treated carrot pomace using microemulsions was higher than untreated carrot pomace. The extraction efficiency of β-carotene using microemulsions was higher compared to 100 % hexane or 100 % glycerol monocaprylocaprate oil. A mathematical model was developed to predict the optimal extraction conditions using transparent microemulsions with high loading of β-carotene, low PDI and small microemulsion particle size. The model predicted that an extraction time of 49.4 min, temperature of 52.2 °C and carrot/microemulsion ratio of 1:70 (w/w) would result in microemulsions with β-carotene loading of 19.6 μg/g, PDI of 0.27 and particle size of 74 nm. This study demonstrates the potential of using oil-in-water microemulsions as extraction media for β-carotene. Figure

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A Rapid and Sensitive Method for Determination of Melamine in Fish,Shrimp, Clam,and Winkle by Gas Chromatography–Mass Spectrometry with Microwave-Assisted Derivatization

A method for rapid and sensitive determination of melamine in aquatic products by gas chromatography–mass spectrometry with microwave-assisted derivatization was proposed in this paper. Melamine was extracted from aquatic product samples using methanol, and the extract was cleaned with a mixed-mode cationic exchange solid phase extraction column. After elution with 5 % ammonia–methanol solution and drying with nitrogen, the residue was derivatized using N,O-bis(trimethylsilyl)trifluoroacetamide containing 1 % trimethylchlorosilane under microwave irradiation for 1 min with a power of 420 W, then detected with gas chromatography–mass spectrometry, and quantified by the external standard method. Some important parameters such as extraction solvent, microwave irradiation power and time, and derivatization reagent volume were investigated and optimized. The results showed that methanol could effectively extracted melamine from aquatic products as well as precipitated the protein in samples. Under the optimum conditions, the detection limit for melamine was as low as 0.006 mg/kg, and the linear range was from 0.02 to 50 mg/kg with a correlation coefficient of 0.9997. The proposed method was applied to the analysis of melamine in aquatic products (fish, shrimp, clam, and winkle), and the recovery for melamine was 89.65–105.16 % with relative standard deviation of 3.0–6.0 %.     

Establishment of an Aqueous PEG 200-Based Deep Eutectic Solvent Extraction and Enrichment Method for Pumpkin (<Emphasis Type="Italic">Cucurbita moschata</Emphasis>) Seed Protein

A novel approach for ultrasound–microwave synergistic extraction (UMSE) of pumpkin seed protein was developed using aqueous poly (ethylene glycol) (PEG 200)-based deep eutectic solvent (DES) as a green extraction medium. Key factors controlling the extraction and optimal operating conditions were optimized by combining the one variable at a time and response surface methodology. Results showed that the PEG 200 as a hydrogen bond donor combined with choline chloride as a typical hydrogen bond acceptor had a highest extraction efficiency among different solvents. The optimal extraction parameters were optimized as follows: PEG 200-based DES concentration, 28% w/w; solid to liquid ratio, 28 g mL^?1; microwave power, 140 W; and extraction temperature, 43 °C. Under the optimal parameters, the actual extraction yield was 93.95 ± 0.23% (n = 3). The precipitation rate of pumpkin seed protein was 97.97% with a precipitation time of only 4 min by using an isoelectric point-ethanol-PEG 200 DES ternary co-precipitation method. Overall, this integrated method of PEG 200-based DES and UMSE exhibits a powerful tool for the rapid and efficient extraction of pumpkin seed protein.     

Optimization of Microwave-Assisted Extraction of Phenolic Antioxidants from Grape Seeds (Vitis vinifera)

Grape seeds (Vitis vinifera) are rich in phytochemicals that have antioxidant properties. The influence of independent variables such as microwave power (100, 150, and 200 W), extraction time (2, 4, and 6 min), and solvent concentration (30%, 45%, and 60% ethanol) and their interactions on total phenols and the antioxidant activity (1,1-diphenyl-2-picrylhydrazyl (DPPH) and ferric ion reducing antioxidant power (FRAP)) were determined; and the microwave-assisted extraction (MAE) process was optimized using a central composite design. The total phenols that were expressed as gallic acid equivalents (GAE), catechin equivalents (CAT), and tannic acid equivalents (TAE) were significantly influenced by the solvent concentration and the time of extraction. A numerical optimization was carried out to obtain the overall conditions for MAE of phenolic antioxidants from grape seed. The response variables were maximized for 6 min of MAE of grape seed (GS) with 32.6% ethanol at 121 W with a desirability function of 0.947. The predicted extraction yields were 13?±?0.89, 21.6?±?1.59, and 15.9?±?1.32 mg GAE, CAT, and TAE, respectively per gram of GS. The predicted antioxidant activity per gram of dry weight GS was 80.9% for the inhibition of DPPH and 135 μM ascorbic acid equivalents for FRAP test. The predicted response values were significantly correlated with the observed ones as follows: GAE r?=?0.995, CAT r?=?0.990, TAE r?=?0.996, DPPH r?=?0.996, and FRAP r?=?0.996.     

Process Intensification by Experimental Design Application to Microwave-Assisted Extraction of Phenolic Compounds from <Emphasis Type="Italic">Juglans regia</Emphasis> L.

Microwave-assisted extraction was applied to Juglans regia L. fresh male flowers and unripe walnut seeds to evaluate the total phenolic contents of the extracts as well as the percentage of water-soluble polyphenols. The research was planned using the Design of Experiments technique to investigate the role on the extraction efficiency of different parameters, such as temperature, time and number of microwave heating cycles, together with their possible interactions. Optimization was achieved by applying a Response Surface Methodology comprising a three-factor, two-level, full-factorial Face-Centred Central Composite Design. The two input variables with a significant effect on the recovery of phenols from fresh male flowers were the extraction temperature and the number of microwave cycles. In the case of unripe walnut seeds, a linear two-factor interaction model was selected, with significant interactions occurring between temperature and time, and time and number of microwave cycles. The best experimental conditions were as follows: 100 °C, 6 min, three microwave heating cycles and 22.7 ± 0.2 mg gallic acid equivalent (GAE)/g (total phenolic content, PC); energy consumption calculations suggested slightly different conditions: 60 °C, 30 min, three microwave heating cycles and 20.7 ± 0.3 mg GAE/g (TPC).     

Optimization of Factors Affecting Extraction of Antioxidants from Mango Seed

A microwave-assisted extraction procedure was developed to obtain extracts rich in antioxidants from mango seed. Central composite design ‘2⁵?+?star’ and response surface methodology were used in order to optimise the extraction factors: the water content in the acetone/water mixture used as extractant, seed weight-to-solvent volume ratio, number of steps, extraction time and pH of water. The results suggest that the extractant composition and the seed weight-to-solvent volume ratio were statistically the most significant factors. The optimum values of the factors that influence the capacity to inhibit lipid peroxidation (evaluated with the β-carotene bleaching test), scavenge 2,2-diphenyl-1-picrylhydrazyl and 2,2′-azino-bis-(3-ethylbenzothiazoline)-6-sulfonic acid-free radicals and obtain extracts with high phenolic compound content (tannins and proanthocyanidins) were three steps; the mixture acetone/water (50:50, v/v) as extractant, a seed weight-to-solvent volume ratio of 1:30 (w/v), an extraction time of 0 min in the microwave (the rest of the extraction process includes homogenisation and centrifugation time), and a pH of 8.0.     

Quality and Nutritional Minerals in Chicken Breast Muscle Treated with Low and High Pulsed Electric Fields

The present research investigated the effects of pulsed electric fields (PEF), low PEF (LPEF, 2.5 kV, 200 Hz and 20 μs) and high PEF (HPEF, 10 kV, 200 Hz and 20 μs), on the quality of chicken breast at 1 and 4 days post-treatment and on the concentrations of minerals (phosphorus, iron, zinc and potassium) in raw and cooked samples. HPEF increased (P < 0.001) the temperature of the chicken breasts. The shear force of chicken breasts was not affected by treatment and post-treatment storage time and their interaction (P > 0.05). The concentrations of P, K, and Zn were decreased by cooking (P < 0.001) only. The concentration of Fe was not affected by treatment, storage time, or cooking. Both LPEF and HPEF treatments did not have negative effects on the quality of chicken breast, indicating that PEF processing of chicken breast does not have a negative impact on the quality.