Chemical characterization, bioactive compounds, and antioxidant capacity of jussara (Euterpe edulis) fruit from the Atlantic Forest in southern Brazil

Samples of fruit from the jussara palm plant (Euterpe edulis), collected in different regions of the state of Santa Catarina, Brazil, were analyzed for chemical composition, phenolic acids, anthocyanins, flavonoids and fatty acids profile. Results indicated that the jussara fruit has a high lipid content (18.45-44.08%), oleic acid (44.17-55.61%) and linoleic acid (18.19-25.36%) are the fatty acids found in the highest proportion, and other components were proteins (5.13-8.21%), ash (1.55-3.32%) and moisture (34.95-42.47%). Significant differences were found in the total phenolic, total monomeric anthocyanins and other flavonoids for the samples from the five cultivation regions. The fruit from region E harvested in summer, with high temperatures and medium altitudes, had the highest contents of total phenolics (2610.86 ± 3.89 mg 100 g⁻¹ GAE) and monomeric anthocyanins (1080.54 ± 2.33 mg 100 g^− 1 cy-3-glu). The phenolic compound included ferulic, gallic, hydroxybenzoic and p-coumaric acids, as well as catechin, epicatechin and quercetin. The results show promising perspectives for the exploitation of this tropical fruit with a chemical composition comprising considerable phenolic acids and flavonoids compounds and showing activity antioxidant.     

Optimisation of the solvent extraction of bioactive compounds from Parkia speciosa pod using response surface methodology

Central composite design was employed to optimise the buffer-to-solids ratio (X₁: 20–50 ml/g), incubation temperature (X₂: 35–55 °C) and time (X₃: 100–200 min), obtaining extracts from Parkia speciosa pod with high total phenolic and flavonoid contents and high antioxidant activities. Analysis of variance showed that the contribution of a quadratic model was significant for the responses. An optimisation study using response surface methodology was performed and 3D response surfaces were plotted from the mathematical models. The optimal conditions based on combination responses were: X₁ = 20 ml/g, X₂ = 35–36 °C and X₃ = 100–102 min. These optimum conditions yielded total phenolic contents of 664–668 mg gallic acid equivalents/100 g, total flavonoid contents of 47.4–49.6 mg pyrocatechol equivalents/100 g, %DPPH_sc of 81.2–82.1%, %ABTS_sc of 78.2–79.8% and FRAP values of 3.2–3.3 mM. Close agreement between experimental and predicted values was found. This methodology could be applied in the extraction of bioactive compounds in the natural product industry.     

Extraction optimization of a hydrocolloid extract from cress seed (Lepidium sativum) using response surface methodology

Extraction conditions for maximum values of yield, viscosity and minimum protein content of hydrocolloid extract from Lepidium sativum seed were investigated using response surface methodology. A Central Composite Face Design (CCFD) with four independent variables: temperature (25–85 °C); pH (3–10); extraction time (10–25 min) and water to seed ratio (10:1–80:1) was used to study the response variables (yield, viscosity and protein content). Data analysis showed that all the variables significantly (p < 0.05) affected the extraction yield and viscosity, whereas the effect of water to seed ratio on protein content was not significant (p > 0.05). Applying a desirability function method the optimum parameters were: extraction temperature 35 °C, pH 10, water to seed ratio of 30:1 and an extraction time of 15 min. At this optimum point, apparent viscosity, yield and protein content were 0.2 Pa s, 6.46% and 0.57%, respectively. The experimental values were very close to the predicted values and were not statistically different (p > 0.05).     

Optimization of subcritical fluid extraction of seed oil from Nitraria tangutorum using response surface methodology

Subcritical fluid extraction (SFE) technology was used to extract oil from Nitraria tangutorum seed. The best possible combination of extraction parameters was found using response surface methodology (RSM) in a three-variable, three-level Box-Behnken experimental design (BBD). The optimum extraction parameters were an extraction time of 40 min, an extraction pressure of 0.60 MPa, an extraction temperature of 44 °C and a raw material particle size of 0.45 mm. Conventional solvent extraction and supercritical CO₂ fluid extraction were comparatively used. The yield of seed oil obtained using SFE was 12.92%, which was similar to or higher than the other methods. The chemical compositions of the seed oil, determined by GC–MS, indicate that its unsaturated fatty acids content was 97%. SFE proved to be an effective technique for extracting oil from N. tangutorum.     

Optimizing conditions for anthocyanins extraction from purple sweet potato using response surface methodology (RSM)

Optimization for purple sweet potato (Ipomoea batatas (L.) Lam) anthocyanins (PSPAs) extraction was investigated using response surface methodology in this paper. PSPAs were extracted using acid-ethanol at different extraction temperature (40-80 °C), time (60-120 min) and solid-liquid ratio (1:15-1:30). The combined effects of extraction conditions on PSPAs yield and color attributes (expressed as L*, C* and H) were studied using a three-level three-factor Box-Behnken design. The results showed that The highest yield (158 mg/100 g dw) of PSPAs were reached at the temperature 80 °C, extraction time 60 min, and solid-liquid ratio 1:32. PSPAs yield indicated a high and significant correlation with L^* (P<0.05; r=−0.961) and it was significantly affected by extraction temperature (P<0.01) and solid-liquid ratio (P<0.05).     

Optimization of nutrient-induced germination of Bacillus sporothermodurans spores using response surface methodology

Spores of Bacillus sporothermodurans are known to be contaminant of dairy products and to be extremely heat-resistant. The induction of endospore germination before a heat treatment could be an efficient method to inactivate these bacteria and ensure milk stability. In this study, the nutrient-induced germination of B. sporothermodurans LTIS27 spores was studied. Testing the effect of 23 nutrient elements to trigger an important germination rate of B. sporothermodurans spores, only d-glucose, l-alanine, and inosine were considered as strong independent germinants. Both inosine and l-alanine play major roles as co-germinants with several other amino acids. A central composite experimental design with three factors (l-alanine, d-glucose, and temperature) using response surface methodology was used to optimize the nutrient-induced germination. The optimal rate of nutrient-induced germination (100%) of B. sporothermodurans spores was obtained after incubation of spore for 60 min at 35 °C in presence of 9 and 60 mM of d-glucose and l-alanine, respectively. The results in this study can help to predict the effect of environmental factors and nutrients on spore germination, which will be beneficial for screening of B. sporothermodurans in milk after induction their germination. Moreover, the chosen method of optimization of the nutrient-induced germination was efficient in finding the optimum values of three factors.     

Bioactivities of açaí (Euterpe precatoria Mart.) fruit pulp,superior antioxidant and anti-inflammatory properties to Euterpe oleracea Mart.

There are two predominant palm tree species producing edible fruit known as “açaí” found widely dispersed through the Amazon: Euterpe oleracea Mart. and Euterpe precatoria Mart. They differ from each other in terms of how the plants grow and their phytochemical composition. E. oleracea (EO) has received considerable attention as a “super fruit” because of its high antioxidant capacity, while studies on E. precatoria (EP) remain rare. In this study, the antioxidant and anti-inflammatory activities of EP fruit pulps were evaluated by different assays including a series of oxygen radical absorbance capacity (ORAC) based assays, the 2,2-diphenyl-1-picrylhydrazyl (DPPH) assay, the cell-based antioxidant protection in erythrocyte (CAP-e) assay, as well as the nuclear factor-kappa B (NF-κB) secreted embryonic alkaline phosphatase (SEAP) assay. Total phenolics were also measured as an indication of the total phenol content. For comparative purposes, the EO fruit pulp was included. The antioxidant capacity of the EP fruit pulp was determined to be superior to the EO fruit pulp in every chemical based assay. In the cell-based CAP-e assay, the EP fruit pulp showed a dose-dependent inhibition against oxidative damage with an IC₅₀ of 0.167 g/l. In the SEAP reporter assay, the EP fruit pulp polyphenol-rich extracts inhibited lipopolysaccharide (LPS)-induced NF-κB activation by 23% (p < 0.05) at 20 μg/ml, whereas the extract of the EO fruit pulp did not show a significant inhibitory effect at comparable doses. In addition, carotenoids were quantified for the first time in EP, since EP has high scavenging capacity against singlet oxygen.     

Flavonoids from acai (Euterpe oleracea Mart.) pulp and their antioxidant and anti-inflammatory activities

Five flavonoids, (2S,3S)-dihyrokaempferol 3-O-β-d-glucoside (1) and its isomer (2R,3R)-dihydrokaempferol 3-O-β-d-glucoside (2) , isovitexin (3), velutin (4) and 5,4′-dihydroxy-7,3′,5′-trimethoxyflavone (5), were isolated from acai (Euterpe oleracea Mart.) pulp. The structures of these compounds were elucidated based upon spectroscopic and chemical analyses. To our knowledge, compounds 1, 2, 4 and 5 were identified from acai pulp for the first time. The in vitro antioxidant activities of these compounds were evaluated by the oxygen radial absorbance capacity (ORAC) assay. The ORAC values varied distinctly (4458.0–22404.5 μmol Trolox equivalent (TE)/g) from 5,4′-dihydroxy-7,3′,5′-trimethoxyflavone (5) to isovitexin (3) and were affected by the numbers/positions of hydroxyl groups, substitute groups, as well as stereo configuration. The anti-inflammatory effects of these compounds were screened by the secreted embryonic alkaline phosphatase (SEAP) reporter assay, which is designed to measure NF-κB activation. Velutin (4) was found to dose-dependently inhibit SEAP secretion in RAW-blue cells induced by LPS, with an IC₅₀ value of 2.0 μM. Velutin (4) also inhibited SEAP secretion induced by oxidised LDL, indicating potential athero-protective effects.     

响应面分析法优化红花黄色素提取工艺条件

在单因素实验的基础上，利用Box-Benhnken中心组合实验和响应面分析法，确定了红花黄酮类黄色素提取的最佳工艺条件，即pH8．9的水溶液为溶剂，液料比25mL／g，提取温度73℃，提取次数3次，每次浸提时间98min。在此条件下．可提取出红花中黄色素总量的98％。     

Optimization of ionic liquid based ultrasonic assisted extraction of puerarin from Radix Puerariae Lobatae by response surface methodology

Ionic liquid (IL) based ultrasonic assisted extraction (ILUAE) was developed for the effective extraction of puerarin from Radix Puerariae Lobatae (RPL). The ILUAE parameters including the type of ILs, IL concentration, RPL amount, ultrasonic power and time were optimized by single-factor experiment and response surface methodology. Under the optimized experimental conditions, the best results were obtained using RPL amount 0.43 g in 10 mL 1.06 mol L⁻¹ 1-butyl-3-methylimidazolium bromide aqueous solution, ultrasonic time 27.43 min and ultrasonic power 480 W. Scanning electron microscope images of RPL samples were obtained to provide visual evidence of the sonication effect. Compared with the conventional ultrasonic assisted extraction and refluent extraction, the proposed ILUAE offered shorter extraction time and remarkable higher efficiencies due to the higher penetration ability and solubility of IL and the cavitation phenomenon produced in the solvent by the passage of an ultrasonic wave, which further supported the suitability of the proposed approach.     

响应面法优化草莓中花青素提取工艺参数

采用超声辅助提取草莓中花青素,并利用响应面分析法（RSM）对草莓花青素的提取工艺进行优化,在单因素实验基础上选取实验因素与水平,根据中心组合（Box-Behnken）实验设计原理采用四因素三水平的响应面分析法对各个因素的显著性和交互作用进行分析,结果表明,料液比对草莓花青素提取量影响最为显著,草莓花青素提取的最优工艺条件为超声功率90W、超声时间14min、料液比1:16、提取温度44℃,在此条件下,花青素提取量实际可达1657.3μg/g,与理论值（1737.3μg/g）基本一致。      

响应面法优化红菊苣花青素的提取工艺及其微胶囊的制备

目的：为了获得提取红菊苣叶中花青素的最优工艺条件和提高红菊苣花青素的稳定性。方法：应用单因素试验和响应面法优化超声波辅助双水相提取工艺,利用响应面设计(BBD)模型对乙醇质量分数、硫酸铵质量浓度、液料比、超声波频率等提取参数进行了优化,选取最优条件。并进一步对提取得到的红菊苣花青素进行微胶囊化,对微胶囊采用红外光谱、扫描电镜对微胶囊化颗粒进行分析。结果：结果表明,超声波辅助双水相提取红菊苣花青素最佳工艺条件在乙醇质量分数为 26% ,硫酸铵质量浓度为22%,超声波频率为36 kHz , 液料比为 26mL/g的条件下,提取花青素含量可达到最高。结论：优化的提取工艺稳定、可靠,微胶囊中芯材与壁材包埋成功,具有很好的实际应用价值。     

响应曲面法优化浸提新疆红树莓中花色苷的工艺研究

以新疆红树莓为原料,选取料液比、浸提温度、浸提时间为三个主要因素,在单因素试验的基础上,采用响应曲面法研究各个因素间的交互作用,优化花色苷提取工艺.结果表明,5.0g红树莓样品中加入经盐酸酸化的体积分数80％乙醇溶液（pH 3）,料液比1∶7（g∶mL）、提取温度51℃、提取时间65 min,该最优条件下得到的花色苷含量为56.45 mg/100 g.     

Chemical and economic evaluation of natural antioxidant extracts obtained by ultrasound-assisted and agitated bed extraction from jussara pulp (Euterpe edulis)

This work aimed to evaluate the influence of ultrasonic and agitated bed extractions on the chemical composition and manufacturing costs of extracts obtained from jussara (Euterpe edulis) pulp. The effects of extraction time (5–180 min), temperature (25–55 °C), ethanol concentration (0–90% in acidified water) and solvent/pulp ratio (5–30 mL/g) on the extraction yield, phenolic content, anthocyanin content, antioxidant capacity and manufacturing costs were assessed. The yields provided by the ultrasound-assisted and agitated bed extractions were not significantly different. The anthocyanins and phenolic compound yields were significantly affected by the extraction time, the ethanol concentration in water and the solvent/feed ratio, but not by the temperature. In general, the antioxidant capacity of the extracts displayed tendencies similar to the anthocyanin and phenolic compound yields. The production of crude extracts obtained by ultrasound and agitated bed extraction incurred greater manufacturing costs compared to the market prices of assai extracts.     

Optimization of extraction process of crude polysaccharides from boat-fruited sterculia seeds by response surface methodology

Response surface methodology (RSM) was applied to optimize the extraction of crude polysaccharides from boat-fruited sterculia seeds. A central composite design was used for experimental design and analysis of the results to obtain the optimal extraction conditions. Extraction temperature, pH, extraction time and water to seed ratio were found to have a significant influence on the yield and purity of the extracted crude polysaccharides, while the three other factors except the water to seed ratio also significantly affected the relative viscosity. Based on the RSM analysis, optimum conditions were: temperature 60–65 °C, time 2.3–3.1 h, pH at 7.0 and water to seed ratio at 75:1. Under the optimized conditions, the experimental values were in close agreement with values predicted by the model. The crude polysaccharides prepared under optimum conditions contained 58.2% total carbohydrates (including uronic acids), 20% proteins, 9% moisture and 4.5% ash. The crude polysaccharides consisted of glucose (22.6%), rhamnose (10.0%), arabinose (7.9%), galactose (5.0%), xylose (0.8%) and galacturonic acid (11.8%).     

Optimization of medium composition for enhanced chitin extraction from Parapenaeus longirostris by Lactobacillus helveticus using response surface methodology

Chitin extraction by biological way, using the lactobacilli Lactobacillus helveticus, is a non-polluting method and offers the opportunity to preserve the exceptional qualities of chitin and its derivatives. However, the major disadvantage of the fermentative way is the low efficiency of demineralization and deproteinization. The aim of our study is to improve the yield of extraction.     

Optimization of conditions for extraction of acid-soluble collagen from grass carp (Ctenopharyngodon idella) by response surface methodology

Grass carp is a freshwater fish species widely known by consumers over the world. Its skin has abundant collagen which possesses many healthy effects. The optimal conditions for collagen extraction were determined by response surface methodology in this work. Box–Behnken design was applied to evaluate the effects of three independent variables (acetic-acid concentration, temperature and time) on the acid-soluble collagen yield of grass carp skin. Correlation analysis of the mathematical-regression model indicated that quadratic polynomial model could be employed to optimize the extraction of acid-soluble collagen. From response surface plots, acetic-acid concentration, temperature and time exhibited interactive effects on the extraction of acid-soluble collagen. The optimal conditions to obtain the highest acid-soluble collagen yield of grass carp skin were an acetic-acid concentration of 0.54 M, a temperature of 24.7 °C and a time of 32.1 h. Under these optimal conditions, the experimental values agreed with the predicted values, using analysis of variance, indicating a high goodness of fit of the model used and the success of response surface methodology for modeling extraction of acid-soluble collagen from grass carp skin.

Industrial relevance

Grass carp is a freshwater fish species with important economic significance. The annual production of grass carp in China was 3.86 million tons in 2005 which was the highest among all the freshwater fish species (http://www.agri.ac.cn/DataIss/ZY/QT/200610/17688.html). The weight of skin accounts for approximately 9% of whole fish. It is interesting to find a way to improve its value. In this work, collagen was extracted from grass carp skin by acetic acid and a mathematical model of extraction was built by response surface methodology. The effects of acetic-acid concentration, extraction time and temperature were under investigation. The results showed that there is an optimal condition to obtain the highest collagen yield. The optimal condition was determined to be an acetic-acid concentration of 0.54 M, a temperature of 24.7 °C and a time of 32.1 h. This research is helpful to develop a new product using grass carp and to fully use this sort of fish resource.     

响应面分析法优化超临界CO2萃取蓝莓花色苷工艺条件的研究

以蓝莓为原料,利用响应面法优化超临界CO2萃取蓝莓花色苷的工艺。在单因素实验基础上,以萃取压力、萃取温度、萃取时间和液料比为影响因素,应用Box-Behnken方法进行四因素三水平实验,以花色苷含量为响应值,进行响应面分析。确定萃取的最佳工艺条件是萃取时间60 min,萃取温度40℃,萃取压力28 MPa,液料比为7∶1（m L∶g）,花色苷含量的预测值为1.59 mg/g,验证值为1.58 mg/g。结果表明利用响应面分析方法对超临界CO2萃取蓝莓花色苷的工艺条件进行优化,可获得最优的工艺参数,从而为进一步的研究提供依据。      

Response surface optimised extraction and chromatographic purification of rosmarinic acid from Melissa officinalis leaves

The extraction of lemon balm (Melissa officinalis) leaves with aqueous methanol was optimised using response surface methodology. Fifteen runs were conducted following a Box-Behnken design (BBD) followed by ridge analysis using the concentration of methanol, the extraction temperature and time as the independent variables and taking the extraction yield of RA from lemon balm as the response variable. The optimal extraction conditions were a methanol concentration of 59.0% (v/v), a temperature of 54.8 °C and a time of 64.8 min, which gave a maximal RA yield of 46.1 mg RA/g dry materials. The RA extract was loaded onto a column packed with Sephadex LH-20 and then was eluted with 100% methanol, which resulted in RA with a purity of 38.8% and a yield of 43.8%. The purity of RA increased by 3.1-fold when compared to its initial purity in the extract obtained from extraction.     

Application of response surface methodology to optimise supercritical carbon dioxide extraction of essential oil from Cyperus rotundus Linn.

Supercritical fluid extraction with carbon dioxide (SC-CO₂ extraction) was performed to isolate essential oils from the rhizomes of Cyperus rotundus Linn. Effects of temperature, pressure, extraction time, and CO₂ flow rate on the yield of essential oils were investigated by response surface methodology (RSM). The oil yield was represented by a second-order polynomial model using central composite rotatable design (CCRD). The oil yield increased significantly with pressure (p < 0.0001) and CO₂ flow rate (p < 0.01). The maximum oil yield from the response surface equation was predicted to be 1.82% using an extraction temperature of 37.6 °C, pressure of 294.4 bar, extraction time of 119.8 min, and CO₂ flow rate of 20.9 L/h.