Influence of ethanol/water ratio in ultrasound and high‐pressure/high‐temperature phenolic compound extraction from agri‐food waste

The valorisation and management of agri‐food waste are currently hot investigation topics which probe the recovery of valuable compounds, such as polyphenols. In this study, high‐pressure/high‐temperature extraction (HPTE) and ultrasound‐assisted extraction (UAE) have been used to study the recovery of phenolic compounds from grape marc and olive pomace in hydroalcoholic solutions. The main phenolic compounds in both extracts were identified by HPLC‐DAD. Besides extraction yield (total polyphenol and flavonoid content) and the antiradical power, polyphenol degradation under HPTE and UAE has also been studied. HPTE with ethanol 75% gave higher phenolic extraction yields: 73.8 ± 1.4 mg of gallic acid equivalents per gram of dried matter and 60.0 mg of caffeic acid equivalents per gram of dried matter for grape marc and olive pomace, respectively. In this study, the efficient combination of ethanol/water mixture with HPTE or UAE has been used to enhance the recovery of phenolic compounds from grape marc and olive pomace. HPLC‐DAD showed that UAE prevents phenolic species degradation damage because of its milder operative conditions.     

Supercritical carbon dioxide extraction of sea buckthorn (Hippophae rhamnoides L.) pomace

BACKGROUND: The goal of this work was to utilize the sea buckthorn pomace, which is the by‐product of a sea buckthorn juice process. Pilot plant supercritical fluid extraction (SFE) experiments were performed in a 5 × 10^?3 m³ volume high‐pressure vessel. The effects of pressure and temperature on extraction yield and recoveries of biologically active components were studied using a 3² full factorial design. The pressure and temperature were varied over the ranges of 30–46 MPa and 313–353 K, respectively. The extract samples were analysed by TLC‐densitometry, UV/VIS spectrofotometry and HPLC methods. RESULTS: The obtained yields changed between 142–164 g kg^?1, according to the solvent power of the supercritical fluid. The recoveries of the different minor components were (g minor components kg^?1 dried raw material): 2.50–4.25 sitosterol, 0.20–1.60 ursolic acid, 0.04–0.18 carotenoid, 0.35–0.42 total tocopherol. CONCLUSION: By evaluation the designed experiments 46 MPa and 333 K were chosen as the optimum conditions. Copyright © 2007 Society of Chemical Industry     

酿酒葡萄皮渣中多酚物质提取的研究

以酿酒后分离的葡萄皮渣为原料,对其多酚类物质的提取条件进行了研究。在单因素试验的基础上,以乙醇体积分数、料液比、浸提时间、浸提温度为影响因素,以葡萄皮多酚得率为评价指标,进行4因素3水平正交试验,确定出的最佳浸提条件为浸提剂为体积分数70%的乙醇,浸提温度80 ℃,浸提时间40 min,按1∶7（g∶mL）的料液比,浸提次数为3次,在此条件下,葡萄皮渣中多酚提取量为30.03 mg/g。     

超声辅助提取葡萄皮颗粒中花色素工艺的优化研究

在超声辅助提取葡萄皮颗粒中花色素的优化工艺中,以单因素试验为依据,通过三元二次旋转组合设计和响应曲面分析法,研究了以温度、时间、料液比为参考因素对葡萄皮颗粒中花色素提取率的影响。试验结果表明:花色素的最佳提取条件为提取温度60.46℃,提取时间7.14 min,料液比5.18。在此反应条件下预测花色素的提取率可达18.81%,花色素的提取条件得到较好的优化结果。     

Supercritical carbon dioxide extraction of okra (Hibiscus esculentus L) seeds

Pilot‐scale supercritical fluid extraction of okra seeds was carried out, using carbon dioxide as solvent, at temperatures of 40, 50 and 60 °C and pressures of 150, 300 and 450 bar. Laboratory‐scale Soxhlet extraction of the ground seeds was carried out with ethanol and n‐hexane. The yields of supercritical fluid extraction and n‐hexane Soxhlet extractions were similar. The ethanol Soxhlet extraction gave the highest yield, but the concentrations of β‐sitosterol and tocopherols in this extract were lower than in the supercritical fluid extraction product. The fatty acid profiles of the extracts were determined, and a high unsaturated/saturated ratio was observed. The fatty acid compositions were only slightly different for oils obtained by the different extraction methods. Copyright © 2005 Society of Chemical Industry     

Optimization of a process for enzyme-assisted pigment extraction from grape (<Emphasis Type="Italic">Vitis vinifera</Emphasis> L.) pomace

A process for enzyme-assisted extraction of polyphenols from grape pomace was developed on laboratory and pilot-plant scale. After resuspending grape pomace in water, the skins were ground and the resulting mash was pasteurized to inactivate the deteriorative enzymes responsible for polyphenol degradation, and then pre-extracted with hot water. Subsequently, cell wall polysaccharides were hydrolyzed. The extract was separated from the solid residue by pressing, and finally spray dried. Before scaling-up, enzymatic hydrolysis was optimized on laboratory scale using a D-optimal design and analyzed by response surface methodology. A mixture of pectinolytic and cellulolytic enzyme preparations (ratio 2:1) yielded the highest amounts of phenolic compounds after 2 h of treatment, applying a dosage of 4,500 mg/kg (based on dry matter) at T = 40 °C and pH 4.0. Aqueous pre-extraction of the pomace followed by enzymatic treatment resulted in significantly improved extraction yields reaching 91.9, 92.4, and 63.6% for phenolic acids, non-anthocyanin flavonoids and anthocyanins, respectively. As the yields obtained were comparable to those from sulfite-assisted extraction, this process can be considered a suitable alternative to the application of sulfite.     

酿酒葡萄渣粕原花青素提取工艺研究

以宁夏酿酒葡萄渣粕为原料,采用溶剂回流提取方法,以原花青素提取得率为考察指标,通过单因素试验及正交试验,确定宁夏酿酒葡萄渣粕中原花青素的提取工艺条件。结果表明,最佳提取工艺条件为:体积分数为50%乙醇,提取温度60℃,料液比1∶10(g∶mL),提取时间45min,提取2次。在此优化条件下进行验证试验,在此最佳条件下,原花青素含量为78.50%,原花青素得率为15.20%。     

响应面法优化木瓜果实中齐墩果酸提取工艺

为优化提取工艺,用超声波法提取木瓜果实中的齐墩果酸,并通过响应面法(RSM)对提取参数进行优化。经高效液相色谱(HPLC)定量分析,齐墩果酸的最佳超声提取条件为溶剂无水乙醇、料液比1∶16、提取温度53℃、提取时间45 min,在该条件下测得木瓜中齐墩果酸含量可达到0.14%。试验提取操作简便、快速,检测方法灵敏、重现性好。     

‘赤霞珠’葡萄皮渣中原花青素的提取工艺研究

研究乙醇浸提法和微波辅助浸提法提取“赤霞珠”葡萄皮渣原花青素的工艺。乙醇浸提法研究提取时间、提取温度、料液比、乙醇浓度四个因素对原花青素提取率的影响;微波辅助浸提法研究微波时间、乙醇浓度、料液比三个因素对原花青素提取率的影响。乙醇浸提法的最佳提取工艺为：提取时间55min,提取温度50℃,料液比1:8.5(g/ml),乙醇浓度55%,提取率为2.61%;微波辅助浸提法的最佳提取工艺为：微波功率320W,微波时间30s,乙醇浓度50%,料液比1:13(g/ml),50℃恒温水浴中浸提30min,提取率为3.99%。在最佳提取工艺条件下研究pH 值对原花青素提取率的影响。乙醇浸提法和微波辅助浸提法分别在pH4.5 和pH5 时,原花青素提取率最大,提取率分别为2.67% 和4.11%,表明酸提高了原花青素的提取率。     

Optimization of Extraction of Bioactive Compounds from Different Types of Grape Pomace Produced at Wineries and Distilleries

Natural extracts obtained from grape pomace are particularly interesting, due to the substantial variety of valuable compounds present with health benefits, specifically phenolic compounds such as anthocyanins, trans‐resveratrol, quercetin, and proanthocyanidins. The production of such extracts has been recognized as a profitable way to valorize grape byproducts, which are low‐value and most abundant. First, the effect of the solvent on the extraction of bioactive compounds from grape pomace is studied. The selected solvents are water and ethanol, biocompatible and available in wineries and distilleries. Then, different types of grape pomace obtained along the various stages of current industrial winemaking and distillation processes are analyzed. As a result, the best stage of the winemaking and distillation processes for pomace valorization is identified, corresponding to the grape byproduct with the highest potential as source of bioactive compounds. These studies were performed with Vitis vinifera variety of Tempranillo grapes (same year, same vineyard).     

Evaluation of the bioactive compounds and the antioxidant capacity of grape pomace

Grape pomace is an agro‐industrial residue produced worldwide and mainly employed for animal feed or as a fertiliser. Several studies have shown that grape pomace is a rich source of bioactive compounds, such as phenolic compounds, polysaccharides, fatty acids and others. Three varieties of grape pomace were evaluated in this study. Antioxidant activity was determined by three different methods, namely, DPPH˙, ABTS and ferrous ion assays. Fatty acids and phenolic compounds were identified, respectively, by gas and liquid chromatography. Results showed that grape pomace is a rich source of polyunsaturated fatty acids and phenolic compounds. Cabernet Sauvignon pomace revealed higher values of total phenolic compounds, total flavonoids and total monomeric anthocyanin, and presented the lowest value of EC₅₀, and thus a higher antioxidant activity among the samples analysed.     

苹果渣果胶超声波辅助提取工艺优化与抗氧化性研究

目的 优化苹果渣中果胶超声波辅助提取工艺,并考查所提取果胶的抗氧化性.方法 在单因素实验的基础上,选取了料液比、pH、提取温度、超声波功率为因变量,以苹果渣中果胶得率为响应值,应用响应面设计方法建立数学模型并进行分析.结果 料液比、pH、提取温度、超声波功率对苹果渣中果胶得率的影响依次为:料液比＞pH＞提取温度＞超声波...     

Valorization of Apple Pomace by Extraction of Valuable Compounds

Apple pomace is a promising source of carbohydrates, proteins, amino acids, fatty acids, phenolic compounds, vitamins, and other compounds with a vast range of food applications. This review focuses on the valorization of apple pomace towards the recovery of the main compounds, namely pectin and polyphenols. Applications, advantages, and drawbacks of conventional extraction (acidic medium under high temperatures) compared with novel extraction technologies are presented. The comparison is based on an extensive literature review of research on extraction of valuable compounds from plant matrixes, particularly apple pomace. Novel extraction techniques involving enzymes, electric field, ultrasound, microwave heating, pressurized liquid, and super/subcritical fluid are also discussed. These techniques offer several advantages, including shorter extraction time, increased yield, reduction—or suppression—of solvents, and minimization of the environmental impact. This paper may help researchers and food industry professionals on the scaling‐up and optimization of eco‐friendly extractions of pectin and phenolic compounds.     

High‐pressure recovery of anthocyanins from grape skin pomace (Vitis vinifera cv. Teran) at moderate temperature

The objective was to evaluate the influences of the high hydrostatic pressure extraction parameters on the recovery of anthocyanins from the grape skin pomace extracts (Vitis vinifera cv. Teran) under moderate temperatures. Studied parameters were: solvents (methanol and ethanol); solvent concentrations (30, 50, and 70%); pressures (300, 400, and 500 MPa); times (3, 6.5, 10 min); and temperatures (22, 26, 30 °C). Predominant anthocyanins in all extracts were malvidins (malvidin‐3‐glucoside as the main compound) representing 55.77% of overall anthocyanin content. The type of solvent did not significantly influence anthocyanin extraction yield, while decreased solvent concentration (increased solvent‐to‐water ratio) significantly improved extraction of anthocyanins. Increase of pressure enhanced extraction yield of the anthocyanins but temperature showed stronger impact on the anthocyanins recovery. This investigation evidenced that the best conditions for HHPE of anthocyanins from grape pomace were extraction time 3.39 min, extraction temperature 29.48 °C, pressure 268.44 MPa and solvent concentration 70%.

Practical applications

Due to increased interest for the use of cheap winery byproducts as a source of expensive polyphenols for functional food production, skins from grape pomace became valuable raw material. Therefore, there is a need to evaluate the influence of HHPE innovative extraction technology on its nutritive value during processing. Optimizing parameters for polyphenolic recovery from grape pomace is directly related with nutritional value and economics of food engineering during industrial processing. Obtained results showed that the HHPE under lower temperatures is suitable for the extraction process of anthocyanins from grape skin pomace, but more research is needed to identify other food‐grade solvents with their corresponding concentrations that are useful for the extraction assisted with high hydrostatic pressure.     

超高压提取木瓜中齐墩果酸的研究

研究了采用超高压提取木瓜中齐墩果酸的最佳工艺条件,并且同回流提取和超声提取方法进行了比较。在单因素实验的基础上,采用正交实验法对木瓜中齐墩果酸的超高压提取工艺进行优选,选用L_9(3~4)进行正交实验,以齐墩果酸的得率为指标,考察粉碎度、超高压压力、保压时间、固液比(g:mL)对齐墩果酸得率的影响。得到的最佳工艺条件为:粉碎度80目、超高压压力350MPa,超高压时间4min,固液比(g;mL)1:20。齐墩果酸的提取得率可达2.72%,同回流提取和超声提取方法相比,超高压提取方法得率高,提取时间短,是提取木瓜中齐墩果酸的适宜方法。     

A systematic approach for extraction of phenolic compounds using parsley (Petroselinum crispum) flakes as a model substrate

The impact of extraction methodology and polarity of extraction solvents on the assay of phenolic compounds was investigated using parsley (Petroselinum crispum) flakes as a model substrate. This systematic study was undertaken to address substantial variations in the extraction procedures, solvents and conditions as described in the recent literature. Five different extraction procedures [shaking, vortex mixing, sonication, stirring and pressurized liquid extraction (PLE)] and three different solvents (methanol, ethanol and acetone), with five different solvent to water ratios per solvent, were used for extraction. Extracts were analyzed for phenolic content by high‐performance liquid chromatography and Folin–Ciocalteu assays. The yields of phenolic compounds extracted with a pressurized liquid extractor were comparable to or better than those of four classical extraction procedures. Optimum extraction efficiency with PLE was obtained when extractions were performed with four extraction cycles using ethanol–water (50:50, v/v). The amount of apiin (4,5,7‐trihydroxyflavone 7‐apiosylglucoside) and malonylapiin (apigenin malonylapiosylglucoside) isolated from parsley varied with the composition of extraction solvent. Apiin extractability was found to be a maximum when the solvent (ethanol, methanol or acetone) to water ratio was 30:70 (v/v), whereas higher amounts of malonylapiin were isolated with a reverse solvent to water ratio (70:30, v/v). Malonylapiin was not detected when parsley samples were extracted with organic solvent to water ratios of 10:90 (v/v) and 30:70 (v/v). Published in 2006 by John Wiley & Sons, Ltd     

Recovery of aroma compounds from Zhenjiang aromatic vinegar by supercritical fluid extraction

Zhenjiang aromatic vinegar, which is produced from sticky rice through solid‐state fermentation, is highly prized as one of the four famous China‐style vinegars, owing to its unique flavour. In this study, a method of supercritical fluid extraction (SFE) was used for the first time to recover aroma compounds from Zhenjiang aromatic vinegar. For this purpose, the optimal conditions for the extraction of aroma compounds by SFE were determined as follows: CO₂ flow rate, 25 L h^?1; extraction time, 2 h; extraction pressure, 35 MPa; and extraction temperature, 323 K. Using headspace solid‐phase microextraction‐gas chromatography–mass spectrometry (HS‐SPME‐GC‐MS) analysis, a total of 49 and 44 aroma compounds were identified in Zhenjiang aromatic vinegar and its SFE extract, respectively. Acetic acid, ethyl acetate, furfural, phenethyl alcohol, tetramethyl‐pyrazine, 3‐hydroxybutanone and benzaldehyde were the main aroma compounds in the vinegar and its SFE extract. SFE is a fast and sensitive method to recovery aroma compounds from the vinegar.     

Characteristics of Extracted Valerenic Acids From Valerian (Valeriana Officinalis) Root by Supercritical Fluid Extraction Using Carbon Dioxide

The extraction of valerenic acids from valerian root by supercritical fluid extraction using CO₂ under different operating conditions was compared to extraction by percolation using 70% ethanol. The yield of total valerenic acids under pressures of 10–20 MPa and temperatures of 40–50°C was about 85% of that achieved by percolation, while the addition of 5% ethanol or methanol as a modifier to the CO₂ resulted in the same yield as percolation. Moreover, maximal extraction was achieved in the faster time of 20 minutes and resulted in a more highly concentrated extract than obtained by percolation which would aid the manufacturing of liquid or dried products. Further studies on a larger scale would clarify the use of this technique commercially.     

Extraction of resveratrol from the pomace of Palomino fino grapes by supercritical carbon dioxide

Resveratrol is a phenolic compound that is present in grapes and has significant benefits for human health. The development of methods to obtain concentrates of this compound is currently a major challenge in the food industry. In the work described here, resveratrol from grape seeds, stems, skin and pomace of the Palomino fino grape variety was extracted by supercritical carbon dioxide extraction. The effect of pressure (100, 400 bar), temperature (35, 55 °C) and the addition of modifier (5% v/v of ethanol) was evaluated to identify optimal resveratrol extraction from this by-product. Extraction yields and concentrations of resveratrol in the extracts were determined. The best results were obtained on working at high pressure and low temperature using 5% v/v ethanol as a co-solvent.     

响应曲面法优化苹果渣可溶性膳食纤维提取工艺

以苹果渣为原料,采用酸水解法从苹果渣中提取可溶性膳食纤维。借助响应面设计分析,考察盐酸质量分数、料液比、浸提时间、浸提温度对可溶性膳食纤维提取率的影响。结果表明,各因素对提取率影响均显著。求解回归方程得到最佳工艺条件为:盐酸质量分数2.0%、液料比17mL/g、浸提时间65min、浸提温度78.2℃,此时可溶性膳食纤维的提取率可达到17.68%。