Antioxidant Capacity of Rapeseed Extracts Obtained by Conventional and Ultrasound‐Assisted Extraction

Ultrasound‐assisted extraction (UAE) and conventional solid–liquid extraction were applied to extract total antioxidants from two rapeseed varieties. The antioxidant capacities (AC) of winter and spring rapeseed cultivars were determined by four different analytical methods: ferric reducing antioxidant power (FRAP), cupric reducing antioxidant capacity (CUPRAC), 2,2′‐diphenyl‐1‐picrylhydrazyl (DPPH), 2,2′‐azino‐bis‐3‐ethylbenzothiazoline‐6‐sulfonic acid (ABTS). The average AC of the studied rapeseed cultivars ranged between 4.21–10.03 mmol Trolox (TE)/100 g, 7.82–10.61 mmol TE/100 g, 8.11–51.59 mmol TE/100 g, 22.48–43.13 mmol TE/100 g for FRAP, CUPRAC, DPPH and ABTS methods, respectively. There are positive correlations between total phenolics (TPC = 804–1625 mg sinapic acid (SA)/100 g) and AC of the studied rapeseed extracts (r = 0.2650–0.9931). Results of the principal component analysis (PCA) indicate that there are differences between the total amounts of antioxidants in rapeseed samples extracted by different extraction techniques. Rapeseed extracts obtained after 18 min of ultrasonication revealed the highest content of total antioxidants. The UAE is a very useful, efficient and rapid technique of oilseed samples preparation for determination of AC by different analytical methods.     

Effects of Different Drying Methods on Bioactive Compound Yield and Antioxidant Capacity of Phyllanthus amarus

Phyllanthus amarus (P. amarus) has been used as a herbal medicine, particularly for liver support, in many countries and its extracts have been shown to possess potent antioxidant and anticancer properties in vitro. The preparation of dried sample is crucial for further extraction and isolation of phytochemicals. In this study, the effects of six different drying methods (hot air, low-temperature air, infrared, microwave, sun, and vacuum drying) on the phytochemical yield and antioxidant capacity were determined to identify the optimal drying method for P. amarus. The results showed that different drying methods, as well as different drying conditions within each method, significantly affected phytochemical yield and antioxidant capacity of P. amarus extracts. Infrared drying at 30°C was the best method for both retention of bioactive compound yield and antioxidant capacity of P. amarus extract, with 12 compounds were identified. In contrast, low-temperature-air drying at 25°C not only required the longest drying time but also significantly reduced the levels of bioactive compounds and antioxidant capacity of P. amarus. Therefore, infrared drying at 30°C is suggested for drying P. amarus for subsequent assessment of bioactivity.     

Comparison between conventional and ultrasound-assisted extractions of natural antioxidants from walnut green husk

Agricultural industries produce substantial quantities of phenolic-rich by-products, which have gained much attention due to their antioxidant properties. Ultrasonic technology was applied for extraction of antioxidants from the walnut green husk using ethanol as a food grade solvent. Response surface methodology (RSM) was used to optimize experimental conditions. The responses were total phenolic content (TPC), ferric reducing antioxidant power (FRAP), scavenging activity of 2,2-diphenyl-1-picrylhydrazyl (DPPH) radical and yield. TPC varied from 6.28 to 7.23mg GA g^?1 dry sample. FRAP and DPPH values varied from 0.33 to 0.46 mmol Fe²⁺ g^?1 of dry sample and 33.98% to 56.31% inhibition, respectively. Extraction yields ranged from 33.04% to 38.72%. The optimal conditions were 60% ethanolwater mixture as solvent, temperature of 60 °C and extraction time of 30 min. Comparison of ultrasonic-assisted extraction (UAE) and conventional extraction was shown that TPC, FRAP, DPPH and yield obtained by UAE during 30 min were significantly higher than by conventional extraction during 16 hours. The extract can be used as substitute of synthetic antioxidants for food products, color and oxidative stabilization.     

Optimum conditions of microwave-assisted extraction for phenolic compounds and antioxidant capacity of the brown alga Sargassum vestitum

This study aimed to optimise microwave-assisted extraction (MAE) conditions for total phenolic compounds (TPCs) and antioxidant activities of the alga Sargassum vestitum by using response surface methodology with Box–Behnken design. The results showed that solvent concentration had the greatest impact on TPC and antioxidant activities of the extracts, followed by radiation time and power. The optimal MAE conditions were ethanol concentration of 70%, radiation time of 75 s and power of 80%. The optimal MAE method showed much better extraction efficacy of phenolics and antioxidant capacities of the extract than conventional and ultrasonic methods.     

The Role of Processing Conditions on the Color and Antioxidant Retention of Jet Tube Fluidized Bed–Dried Blueberries

Jet tube fluidized bed drying was investigated as a means of rapidly generating shelf-stable and high-quality sweetened and nonsweetened blueberries. Sugar-infused and noninfused scarified Rabbiteye blueberries (Vaccinium ashei ‘Brightwell’) were dried at 99, 107, and 116°C. Prior scarification of the blueberry surface aided in decreasing the drying time. Increased lightness (L*) values were most notable at higher drying temperatures for sugar-infused blueberries, suggesting loss of pigments. Total monomeric anthocyanins level, initially 7.65 mg cyanidin-3-O-glucoside equivalents (C3G eq)/g extract, decreased as drying temperature increased and ranged between 4.07 down to 1.51 mg C3G eq/g extract for dried blueberries. The total phenolics content increased with drying for noninfused blueberries, with highest levels of 31.6 mg gallic acid equivalents (GAE)/g extract for samples dried at 107°C. With the exception of sugar-infused berries dried at 107 and 116°C, the dried blueberries maintained or demonstrated slightly increased hydrophilic oxygen radical absorbance capacity (H-ORAC_FL) values, indicating that their antioxidant capacity was retained upon drying. Blueberries dried at 107°C possessed the greatest preference scores and best retention of blueberry flavor and required a relatively short drying time.     

Evaluation of Antioxidant Properties and Mineral Composition of Purslane (Portulaca oleracea L.) at Different Growth Stages

The main objective of this research was to appraise the changes in mineral content and antioxidant attributes of Portulaca oleracea over different growth stages. The antioxidant activity was measured using 1,1-diphenyl-2-picrylhydrazyl (DPPH), ferric-reducing antioxidant power (FRAP) assays. The iodine titration method was used to determine the ascorbic acid content (AAC). DPPH scavenging (IC(50)) capacity ranged from 1.30 ± 0.04 to 1.71 ± 0.04 mg/mL, while the ascorbic acid equivalent antioxidant activity (AEAC) values were 229.5 ± 7.9 to 319.3 ± 8.7 mg AA/100 g, total phenol content (TPC) varied from 174.5 ± 8.5 to 348.5 ± 7.9 mg GAE/100 g. AAC 60.5 ± 2.1 to 86.5 ± 3.9 mg/100 g and FRAP 1.8 ± 0.1 to 4.3 ± 0.1 mg GAE/g. There was good correlation between the results of TPC and AEAC, and between IC(50) and FRAP assays (r(2) > 0.9). The concentrations of Ca, Mg, K, Fe and Zn increased with plant maturity. Calcium (Ca) was negatively correlated with sodium (Na) and chloride (Cl), but positively correlated with magnesium (Mg), potassium (K), iron (Fe) and zinc (Zn). Portulaca olerecea cultivars could be used as a source of minerals and antioxidants, especially for functional food and nutraceutical applications.     

Antioxidant capacity of rapeseed meal and rapeseed oils enriched with meal extract

Response surface methodology (RSM) was used to evaluate the quantitative effects of two independent variables: solvent polarity and temperature of the extraction process on the antioxidant capacity (AC) and total phenolics content (TPC) in meal rapeseed extracts. The mean AC and TPC results for meal ranged between 1181–9974 µmol TE/100 g and 73.8–814 mg sinapic acid/100 g of meal. The experimental results of AC and TPC were close to the predicted values calculated from the polynomial response surface models equations (R² = 0.9758 and 0.9603, respectively). The effect of solvent polarity on AC and TPC in the examined extracts was about 3.6 and 2.6 times greater, respectively, than the effect of processing temperature. The predicted optimum solvent polarity of ε = 78.3 and 63.8, and temperature of 89.4 and 74.2°C resulted in an AC of 10 014 µmol TE/100 g and TPC of 863 mg SAE/100 g meal, respectively. The phenolic profile of rapeseed meal was determined by an HPLC method. The main phenolics in rapeseed meal were sinapine and sinapic acid. Refined rapeseed oils were fortified with an extract – rich in polyphenols – obtained from rapeseed meal. The supplemented rapeseed oil had higher AC and TPC than the refined oil without addition of meal extracts. However, AC and TPC in the enriched oils decreased during storage. The TPC in the studied meal extracts and rapeseed oils correlated significantly (p<0.0000001) positively with their AC (R² = 0.9387). Practical applications: Many bioactive compounds extracted from rapeseed meal provide health benefits and have antioxidative properties. Therefore, it seems worth to consider the application of antioxidants extracted from the rapeseed meal for the production of rapeseed oils with potent AC. Moreover, antioxidants extracted from the rapeseed meal were added to refined rapeseed oil in order to enhance its AC. AC was then tested by FRAP assay. FRAP method is based on the reduction of the ferric tripyridyltriazine (Fe³⁺‐TPTZ) complex to the ferrous tripyridyltriazine (Fe²⁺‐TPTZ), and it is simple, fast, low cost, and robust method. FRAP method does not require specialized equipment and can be performed using automated, semi‐automatic, or manual methods. Therefore the proposed FRAP method can be employed by the fat industry laboratories to asses the AC of rapeseed oils and meal.     

Phytochemical retention and antioxidant capacity of xao tam phan (Paramignya trimera) root as prepared by different drying methods

Xao tam phan (Paramignya trimera (Oliv.) Guillaum) has been used as an herbal medicine for the treatment of cancer or cancer-like diseases in recent years, particularly in Vietnam. Drying is an important step for preparation of dried materials for storage and further investigation; however, the effects of drying must be taken into account when processing samples, because this can have profound effects on the stability of phytochemical compounds and the biological activity of the dried P. trimera root. As such, this study assessed the effects of four different drying methods (conventional, hot air, vacuum, and microwave) on phytochemical retention and antioxidant capacity of P. trimera root, to identify an optimal drying method for P. trimera root. The results showed that the drying methods significantly affected phytochemical levels and antioxidant capacity of P. trimera root and that among the four drying methods tested, microwave drying (400 W) had the highest levels of phytochemical compounds, with total phenolic, total flavonoid, proanthocyanidin, and saponin contents of 11.27 mg GAE, 19.88 mg RE, 3.98 mg CE, and 267.15 mg EE/gram of dried sample, respectively. Dried sample prepared using this method had antioxidant capacity comparable to that of other drying methods. In addition, this method had the shortest drying time (0.28 h) and consumed the least energy (0.28 kWh). Therefore, microwave drying should be considered for drying P. trimera root for further investigation and utilization.     

Solvent and Extraction Conditions Control the Assayable Phenolic Content and Antioxidant Activities of Seeds of Black Beans,Canola and Millet

The effects of extraction solvent and conditions on the total phenolic content (TPC) and antioxidant activity of black beans, canola and foxtail millet were investigated. The antioxidant activity was assayed using 2,2‐diphenyl‐1‐picrylhydrazyl radical scavenging activity (DRSA) and oxygen radical absorbance capacity (ORAC). Four solvent systems, namely 70 % acetone, 80 % ethanol, 80 % methanol and a mixture of acetone/methanol/water (7:7:6, v/v/v) were used. The extraction methods adopted in this study included refluxing, homogenization, cold extraction and sonication. The TPC as measured using the Folin Ciocalteu's method were 12.35–28.39, 2.43–16.73, and 1.78–5.06 µmol catechin equivalents/g dry matter (dm) for canola, black beans and foxtail millet, respectively. Aqueous acetone afforded the highest TPC for black beans and canola. Within the same solvent system used, the TPC, DRSA and ORAC obtained from different extraction techniques differed for black beans, canola and foxtail millet. The results demonstrated that the solvent system as well as method influenced the extraction of phenolic compounds and their antioxidant activities, depending on the type of matrix in which phenolics were embedded.     

Proximate Composition and Antioxidant Potential of Leaves from Three Varieties of Mulberry (Morus sp.): A Comparative Study

In this study, leaves of three indigenous varieties of Mulberry namely, Morus alba L., Morus nigra L. and Morus rubra L. were investigated for their antioxidant potential and their proximate composition was determined. The yields of 80% methanolic extracts ranged between 8.28–13.89%. The contents of total phenolics (TPC), total flavonoids (TFC) and ascorbic acid (AA) ranged between 16.21–24.37 mg gallic acid equivalent (GAE)/g, 26.41–31.28 mg rutin equivalent (RE)/g and 0.97–1.49 mg/g, respectively. The antioxidant activity of leaf extracts was evaluated by measuring 1,1-diphenyl-2-picrylhydrazyl (DPPH^•) radical scavenging actity, 2,2′-azino-bis-(3-ethylbenzthiazoline-6-sulphonic acid (ABTS^•+) radical cation scavenging capacity and ferric ion reducing power and values ranged between 1.89–2.12, 6.12–9.89 and 0.56–0.97 mM Trolox equivalent/g of dried leaves, respectively. The investigated features reveal good nutritive and antioxidant attributes of all the varieties with mutually significant differences.     

Optimized Drying of Kaprow Leaves for Industrial Production of Holy Basil Spice Powder

The present study investigated the changes in color, volatile compounds, total phenolic content, total flavonoid content, and antioxidant activity of two holy basil leaves (kaprow in Thai) Ocimum sanctum L. cultivars, kaprow khao and kaprow daeng, after three drying treatments, namely hot air (HA), low relative humidity air drying (LRH), and far-infrared radiation (FIR). Overall, HA dried showed a greater decrease in L values than did LRH and FIR dried for both kaprow cultivars. A significant decrease in total phenolic content (TPC), total flavonoid content (TFC), and ferric reducing antioxidant power (FRAP) was found in hot-air (HA) dried compared to fresh leaves, while TPC, TFC, and FRAP in LRH and FIR dried kaprow were significantly increased. Kaprow daeng and kaprow khao attributes represented by such compounds as β-caryophyllene, methyl eugenol, and eugenol were found to increase during drying. We found that eugenol was a major volatile compound ranging from 18% in HA dried to 23% in FIR dried samples in kaprow khao, whereas methyl eugenol was the main volatile compound in kaprow daeng ranging from 35% in fresh to 49% in FIR dried samples. Our results have demonstrated that LRH and FIR should be considered as a suitable drying method for kaprow with respect to preserving its color, antioxidant property, phenolic compounds, and volatile compounds. The present study has provided useful information for industrial use of kaprow powder production.     

Optimization of microwave-assisted extraction of bioactive compounds from pistachio (Pistacia vera L.) hull

ABSTRACT

Phenolic compounds were extracted from pistachio hull using microwave-assisted solvent extraction (MASE). The effects of four parameters, microwave power, extraction time, solvent to sample ratio, and ethanol concentration were evaluated. The extraction conditions were optimized by response surface methodology to enhance the total phenolic content (TPC). Optimal conditions were found as 140 W microwave power, 4.5 min extraction time, 19:1 (v/w) solvent to sample ratio, and 56% ethanol concentration to get maximum TPC (62.24 mg GAE/g dry hull). Also, MASE was compared with conventional solvent extraction (CSE) and MASE gave higher TPC, yield, and antioxidant activity.     

Antioxidant activity of strawberry (Fragaria × ananassa Duch.) leaves

Antioxidant activity of aqueous extracts from two cultivated strawberry leaves, Senga Sengana and Mount Everest, obtained by maceration, reflux extraction and ultrasonic extraction, was investigated. Antioxidant activity of extracts was assessed by DPPH, FRAP, FIC and H₂O₂ test; total phenolics and flavonoids were assessed by Folin–Ciocalteu and aluminium chloride methods, respectively. Extract obtained from Senga Sengana by reflux extraction, containing higher amounts of extractive matter, total phenolics and flavonoids, has shown higher antioxidant activity (EC_50(DPPH) = 10.4 μg/mL; FRAP = 258.61 mgFe²⁺/g dry extract.; FIC activity = 62.6% in concentration of 2 mg/mL; H₂O₂ scavenging = 25.43% in concentration of 0.5 mg/mL) compared to extracts obtained by other extraction techniques. Rutin, coumaroyl-galloyl-glucopyranoside, hydroxyphenylethyl-coumaroyl-glucopyranoside, derivates of hydroxyphenylethyl-coumaroyl-glucopyranoside, chlorogenic acid and p-coumaroylhexose have been identified by UHPLC–DAD–HESI–MS analysis.     

The role of drying methods on enzymatic activity and phenolics content of impregnated dried apple

Infusion of antioxidants into vegetables is a new food strategy managed by matrix processing. Raw and blanched apple were air- or freeze-dried. In the case of freeze-dried samples, different freezing methods were previously applied: conventional (?28°C), blast freezing (?30°C), and liquid N₂ (?196°C). Afterwards, air- and freeze-dried samples at different conditions were impregnated with a concentrated (40°Brix) tea extract and finally, air-dried for their stabilization. Total phenolic content (TPC), antioxidant capacity (AC), enzymatic activity, and microstructure were analyzed. Regardless of pretreatments, the impregnation and the further drying improved the antioxidant potential. Samples with the most porous microstructure free of degradative enzymes provided high AC (78.5?±?0.9?mg Trolox/g dried matter) and TPC (16.7?±?0.2?mg GAE/g dried matter).     

OBTAINING SCARLET SAGE (SALVIA COCCINEA) EXTRACT THROUGH HOMOGENIZER- AND ULTRASOUND-ASSISTED EXTRACTION METHODS

Scarlet sage (Salvia coccinea) leaves were extracted with water, ethanol, methanol, and aqueous mixtures of those solvents by homogenizer-assisted extraction (HAE) and ultrasound-assisted extraction (UAE) methods, which are novel technologies used for this purpose. The best results were compared with those obtained by the conventional Soxhlet method (SM). Total phenolic content was expressed in gallic acid equivalent (GAE) per g of dried leaf. Free radical scavenging activity for the antioxidant capacity was tested by 1,1-diphenyl-2-picryl hydrazyl (DPPH) radical. The greatest amount of extraction was achieved by pure water with the value of 368.87 mg/g dried matter and the highest total phenolic content was observed by 100% methanol as 43.18 mg-GAE/g dried matter, both obtained by the HAE method. The mint leaves extracted by SM exhibited the highest antioxidant capacity, with a value of 90.55% for inhibition of DPPH radical.     

Optimization of Microwave-Assisted Extraction of Astaxanthin from Haematococcus Pluvialis by Response Surface Methodology and Antioxidant Activities of the Extracts

Abstract

Microwave-assisted extraction (MAE) was applied for the extraction of astaxanthin from Haematococcus pluvialis and response surface methodology (RSM) was used to optimize extraction parameters to the content of astaxanthin. Four independent variables such as microwave power (W), extraction time (sec), solvent volume (mL), and the number of extraction were optimized in this paper. The optimal conditions were determined and tri-dimensional response surfaces were plotted from the mathematical models. The F-test and p-value indicated that microwave power, extraction time, the number of extraction, and their quadratic had a highly significant effect on the response value (p <0.01), then the solvent volume and the interaction effects of microwave power and the number of extraction also displayed significant effect (p <0.05). Considering the extraction efficiency, the optimized conditions of MAE were as follows: microwave power was 141 W, extraction time 83 sec, solvent volume 9.8 mL, the number of extraction four times. About 594 ± 3.02 µg astaxanthin was extracted from Haematococcus pluvialis the dried powders (100 mg) under the optimal conditions, and it close to the predicted contents (592 µg). The antioxidant activities of the extracts obtained under optimal conditions were analyzed, and the results showed that the extracts presented strong ability of inhibiting the peroxidantion of linoleic acid, exhibited strong radical-scavenging properties against the DPPH, as well as strong reducing power.     

Phenolics and Antioxidant Activity of Mulberry Leaves Depend on Cultivar and Harvest Month in Southern China

To elucidate the effects of cultivar and harvest month on the phenolic content and antioxidant activity of mulberry leaves, four major phenolics, including chlorogenic acid (ChA), benzoic acid (BeA), rutin (Rut) and astragalin (Ast), were quantified using an HPLC-UV method. Leaves from six mulberry cultivars, collected from April to October, were analyzed. The antioxidant activity of mulberry leaves was assessed by ferric reducing antioxidant power (FRAP), hydroxyl radical scavenging activity (HSA) and superoxide radical scavenging activity (SSA) assays. The results showed that the total values of the four phenolic compounds ranged from 2.3 dry weight (DW) to 4.2 mg/g DW, with ChA being the major compound. The mean total phenol (TP) content of the six cultivars ranged from 30.4 equivalents (GAE) mg/g DW to 44.7 GAE mg/g DW. Mulberry leaves harvested in May had the highest TP content. Moreover, the antioxidant activities of mulberry leaves harvested from April to October differed noticeably. In general, Kq 10 and May were considered to be a better cultivar and harvest month concerning phenolic content and antioxidant activity, respectively.     

Microwave-Assisted Batch Extraction of Polyphenols from Sea Buckthorn Leaves

Extraction of polyphenols from sea buckthorn leaves using microwave-assisted extraction (MAE) is described. The influence of different parameters on the extraction process (reactor type, stirring rate, extraction time, temperature, ethanol/water ratio) was studied. The polyphenolic extracts were analyzed in order to determine the total phenolic content (TPC) either by the Folin–Ciocalteu method or by differential pulse voltammetry (DPV), and the concentration of the main polyphenolic compounds by high-performance liquid chromatography (HPLC). The specific microwave energy was also determined. MAE resulted in a shorter extraction time (7.5 versus 30 min for the conventional method). The best results for MAE were obtained at a temperature of 90°C, using a solvent/plant ratio of 20/1 and 50% ethanol in the extraction solvent. The highest values of antioxidant capacity were obtained for polyphenolic extracts resulted from microwave extraction.     

Major Phenolic Compounds, Antioxidant Capacity and Antidiabetic Potential of Rice Bean (Vigna umbellata L.) in China

Interest in edible beans as nutraceuticals is increasing. In the present study, the individual phenolic acids, the total phenolic content (TPC), the total flavonoid content (TFC), and the antioxidant and antidiabetic potential of 13 varieties of rice beans from China were investigated. Eight phenolic compounds (catechin, epicatechin, p-coumaric acid, ferulic acid, vitexin, isovitexin, sinapic acid, quercetin) were analyzed on an ultra-performance liquid chromatography (UPLC) mass spectrometry (MS) system. The rice bean varieties had significant differences in total phenolic compounds (ranging from 123.09 ± 10.35 to 843.75 ± 30.15 μg/g), in TPC (ranging from 3.27 ± 0.04 to 6.43 ± 0.25 mg gallic acid equivalents (GAE)/g), in TFC (ranging from 55.95 ± 11.16 to 320.39 ± 31.77 mg catechin (CE)/g), in antioxidant activity (ranging from 39.87 ± 1.37 to 46.40 ± 2.18 μM·TE/g), in α-glucosidase inhibition activity (ranging from 44.32 ± 2.12 to 68.71 ± 2.19) and in advanced glycation end products formation inhibition activity (ranging from 34.11 ± 0.59 to 75.75 ± 0.33). This study is the first report on phytochemistry and biological activities in rice beans.     

Optimization of ultrasound-assisted extraction of bioactive compounds from B. forficata subsp. Pruinosa

Extracts containing bioactive compounds were obtained from Bauhinia forficata leaves by ultrasound-assisted extraction (UAE) with three different solvents (n-hexane, ethyl acetate, and ethanol) and were compared with those obtained by a conventional method (maceration). Box-Behnken experimental design was applied to examine and optimize the effect of the extraction temperature (40°C-60°C), power (20%-80%), and sample to solvent ratio (1:10 to 1:20 (w/v)) on the total phenolic content (TPC), total flavonoid content (TFC), and the ferric reducing antioxidant power (FRAP) of B. forficata leaf extracts. This experimental design generated second-order polynomial models, which accurately describe the experimental data, allowing the prediction of optimal conditions for the investigated responses. Optimal extraction was achieved under the following conditions: 80% power, temperature of 41°C, and a 1:20 sample to solvent ratio. Under these conditions, the experimental yield was 8.33 ± 0.32%, total phenolic content was 59.47 ± 0.71 mg GAE · g_extract⁻¹, total flavonoid content was 62.30 ± 3.38 mg QE · g_extract⁻¹, and the ferric reducing antioxidant power was 726.7 ± 15.7 μmol Fe(II)EQ · g_extract⁻¹, which were close to the predicted values, which validated the models. The major compounds found in B. forficata extracts were tocopherols, phytol, heneicosane, and β-Sitosterol.