Comparative evaluation of the composition of vegetable essential and fixed oils obtained by supercritical extraction and conventional techniques: a chemometric approach

We compared by a chemometric approach the composition of essential (EO) and fixed (FO) oils previously obtained from several vegetable matrices by supercritical CO₂ extraction (CO₂-SFE) and conventional techniques (n-hexane in a Soxhlet apparatus and hydrodistillation). A multivariate approach, by determining the principal components analysis (PCA) applied to data of FO fatty acids and EO volatile compounds, generally indicated that the vegetable oils extracted with CO₂-SFE tightly clustered with those obtained by conventional methods. The graphical distances calculated in the PCA plots between the score of each SFE oil and the corresponding conventional oil revealed that the CO₂-SFE FO and EO profiles were quite similar to conventional oils, with the additional benefit of not having unwanted traces of solvent. SFE FO were more similar to conventional oils than SFE EO (mean values of calculated graphical distances were 0.83 and 1.46 for FO and EO, respectively). Our results strongly corroborate the role of CO₂-SFE as a suitable, environmentally safe and efficient method alternative to the traditional ones for the extraction of natural vegetable oils for food and pharmaceutical applications.     

Quality of industrial pectin extracted from peach pomace at different pH and temperatures

Two molecular characteristics of pectin related to good gelling properties of the polysaccharide are degree of esterification (DE) and length of molecular chain. Industrial pectin from peach pomace was extracted at different pH and temperatures. DE, acetyl content, intrinsic viscosity and molecular weight of the samples were analysed, and the effect of the extraction conditions on these parameters were studied. On the basis that high DE and intrinsic viscosity indicate good gelling pectin or good quality of pectin has chains with low acetyl content, all extracted samples were compared using a multicriteria method in order to find the best extraction conditions. © 1999 Society of Chemical Industry     

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...     

葛粉掺假的傅里叶变换红外光谱法鉴别研究

以葛粉及葛粉中分别掺假红薯粉和马铃薯粉作为研究对象,采集400～4000cm-1波数范围内的红外傅里叶变换光谱,结合主成分分析对样品的进行聚类划分。并通过Fisher判别,建立葛粉真伪的判别方程。分别以样本回判及外部验证考察模型可靠性。结果表明：葛粉、红薯粉与马铃薯粉及三者不同比例混合样品的二维主成分分布位于不同区域,且葛粉与掺假葛粉之间无重叠。判别方程经样本回判及外部验证表明,葛粉中掺假红薯粉和葛粉中掺假马铃薯粉的自身验证准确率分别为93.3%和100%;交互验证准确率分别为86.7%和92.0%。此方法具有很好的鉴别作用,可作为葛粉中掺假红薯粉和马铃薯粉的一种鉴别方法。     

响应面法优化杨梅渣中槲皮素提取工艺的研究

采用超声辅助提取的方法,通过单因素结合响应面分析,对杨梅渣活性成分槲皮素的提取工艺进行了优化。在单因素实验的基础上,根据中心组合（Box-Benhnken）实验设计原理,采用三因素三水平的响应面分析法,以槲皮素提取率为响应值进行回归分析。结果表明,杨梅渣中槲皮素的最佳提取工艺为:提取时间33.5min,超声功率为254.6W,乙醇浓度为62.32%,料液比1∶20,槲皮素提取率为3.82mg/100g,与模型预测值基本相符。      

基于响应曲面法优化天麻多酚的提取工艺

目的:对天麻总多酚的提取工艺进行优化。方法:以天麻为材料在单因素实验结果的基础上,采用三因素三水平的Box-Behnken响应曲面设计。结果:天麻提取的最佳条件为乙醇浓度57%,提取温度69℃,提取时间53min,该条件下多酚提取含量达44.96mg GAE/g,且提取温度对总多酚的得率影响最大。结论:在最佳条件下天麻多酚得率实际值是预测值的98.48%,接近预测值,可用于天麻多酚的提取。      

Effects of ultrasound treatment and concentration of ethanol on selectivity of phenolic extraction from apple pomace

The extraction of polyphenols from apple pomace was studied using ultrasound, ethanol/water mixtures and moderate temperatures, 20–37 °C. The extraction kinetics and extraction yields of catechin and total phenolic content (TPC) were evaluated at different times of ultrasound treatment (t_u) and concentrations of ethanol (C_e). The highest extraction efficiency of TPC was observed at t_u = 30 min, C_e = 50% and total extraction time of t_e = 60 min. The high selectivity of catechin extraction was demonstrated by analysing the relative content of catechin (R = C_c/TPC) in dependence of applied extraction protocol. The initial portions of extracts at small levels of TPC (≤50 mg per 100 DM) were richer in catechin content (R ≈ 15%–31%), whereas the last portions of extracts with high level of TPS were more exhausted in catechin (R ≈ 2%).     

超声波辅助酶法提取草鱼皮胶原蛋白及其纯化

本文研究了超声波辅助提取草鱼皮胶原蛋白的工艺。以超声功率、超声时间和酶解时间为实验因素,胶原蛋白提取率为响应值,利用Box-Behnken设计实验及响应面法分析实验,确定其最佳提取工艺条件。结果显示:最佳工艺条件为超声功率310 W,超声时间10 min,酶解时间29 h,此时胶原蛋白提取率达到68.67%,与模型理论预测值（68.80%）较为相近,相对误差仅为0.189%。通过十二烷基硫酸钠-聚丙烯酰胺凝胶电泳图谱（SDS-PAGE）和傅里叶红外光谱（FTIR）谱图,对比超声波作用下与无超声波作用的胶原蛋白发现,超声波对胶原蛋白结构无明显影响。      

Differentiation of Peats Used in the Preparation of Malt for Scotch Whisky Production Using Fourier Transform Infrared Spectroscopy

It is not known if peats derived from different areas of Scotland have distinctive chemical constituents that could impact on malt whisky in discernible organoleptic ways. Fourier transform‐infrared (FT‐IR) spectroscopy was used as a high throughput screening method to investigate discrimination of a large number of peat samples from six different geographical origins around Scotland. The data were analysed statistically (using principal component‐discriminant function analysis) and the results showed a difference between peat samples from different geographical origins. Therefore, we have shown that FT‐IR spectroscopy provides a quick and simple method for differentiating peat types.     

苹果品种和酿造工艺对苹果酒中酚类物质的影响研究

研究不同苹果品种及加工工艺与苹果酒中最终酚类物质的含量和种类的关系,了解不同苹果酒中酚类物质含量的差异.选用甘肃天水提供的两种不同工艺的6款苹果酒样,测定其中的总酚、酚酸及黄烷-3-醇的含量.苹果酒的总酚含量(以没食子酸计)较高,3种苹果酒中的主要酚类物质中,酚酸主要以原儿茶酸、绿原酸、p-香豆酸以及咖啡酸为主;黄烷-3-醇以儿茶素和表几茶素居多.结果表明,不同苹果品种之间酚类物质的含量及类别差异很大,相同品种的苹果酒中多酚的构成及含量会受到酿造工艺的影响.     

Performance of green and conventional techniques for the optimal extraction of bioactive compounds in bee pollen

The exploitation of phenolic compounds in different fields has motivated researchers to explore eco-friendly and efficient extraction techniques. This study aimed to comparatively reveal that green extraction techniques (microwave- and ultrasound-assisted) are alternative to conventional extraction (maceration and magnetic stirring) with positive impact on the phenolic content, antioxidant activity, and bioactive profile of bee pollen extracts. The highest total phenolic and flavonoid content was reached using the microwave-assisted technique (MAE) with equivalent values of 28 and 8 mg g⁻¹, with magnetic stirring and maceration showing a lower value. The composition profile of the extracts revealed the presence of twenty-six bioactive compounds, including thirteen phenolics and thirteen phenylamides. Although the extraction technique had little impact on the chemical diversity, the amount of bioactive compounds raised significantly with the use of the green extraction techniques, with gains between 40% and 60% for phenolics and up to 200% for phenylamides. The radical scavenging activity and the reducing power of the extracts confirmed that bee pollens are potent antioxidant source, with the most bioactive extracts corresponding to green extraction techniques. Consequently, all findings recommend the use of MAE as the technique most effective for the extraction of bioactive compounds from naturally encapsulated structures such as bee pollen.     

Influence of solvent and temperature on extraction of phenolic compounds from grape seed,antioxidant activity and colour of extract

This study was aimed to investigate the influence of solvent (water and ethanol in concentration: 50%, 70% and 96%) and extraction temperature (25–80) °C on polyphenols extraction of grape seed (Vitis vinifera L. cv. “Frankovka”) cultivated in Eastern Croatia. The best results were reached using 50% ethanol at 80 °C. The most abundant individual polyphenolic compound was catechin which makes the average of 45.11% of the total phenolic content followed by epicatechin (34.45%), procyanidin B₂ (12.90%), gallic acid (5.34%), gallocatechin (1.58%), epicatechin gallate (1.01%). The antioxidant activity of extracts was determined by DPPH‐method and it was highly dependent on extraction solvent and temperature. The total extractable proanthocyanidins content of extract had the highest positive correlation (r = 0.994) with antioxidant activity, which indicated that these compounds might be the most important antioxidant in examined grape seed extracts. Relationship between phenolic content and colour of extracts was observed.     

近红外光谱结合化学计量法快速无损鉴别燕麦

提出了一种基于近红外光谱技术与化学计量学的燕麦无损鉴别方法。通过近红外光谱仪测定了5个品牌与劣质燕麦的光谱曲线,利用连续小波变换方法对光谱进行预处理,然后基于标准偏差与相对标准偏差的变量筛选方法筛选出具有代表的15个波数点,最后结合主成分分析法对不同燕麦样品快速鉴别。结果表明:连续小波变换可以有效地消除光谱中的背景干扰,提取光谱有效信息,波长筛选方法可以大大提高主成分分析结果的鉴别能力。通过结合近红外光谱分析技术与化学计量学方法,可对中国国产品牌、进口品牌和劣质燕麦进行准确鉴别。     

四种不同品种猪肉滋味成分差异研究

为全面了解瘦肉型猪肉、定远黑猪肉、安庆六白猪肉和皖南花猪肉滋味成分的差异,将这4种新鲜猪肉分别熟制后,分析了游离氨基酸、肌苷酸、鸟苷酸及总还原糖的含量,并根据各氨基酸的含量,采用主成分分析法分析4种猪肉滋味的差异。结果表明:瘦肉型猪肉香气与其他3种中国地方猪肉的滋味有着明显差异,其余3种中国地方猪肉的滋味也有一定差异;对瘦肉型猪肉与其他地方猪肉滋味差异影响较大的氨基酸有:丙氨酸(Ala)、苏氨酸(Thr)、丝氨酸(Ser)、谷氨酸(Glu)、甘氨酸(Gly)、缬氨酸(Val)、赖氨酸(Lys)、精氨酸(Arg)。肌苷酸(IMP)、鸟苷酸(GMP)在这4种猪肉中的含量差异明显,又因这两种物质与谷氨酸之间还有鲜味协同作用,因此这两种核苷酸对猪肉滋味差异的影响也较显著。      

Supercritical fluid and solid–liquid extraction of phenolic antioxidants from grape pomace: a comparative study

Distilled white grape pomace (Vitis vinifera var. Garnacha) was subjected to extraction by using two different methods: (1) solid–liquid extraction (SLE) employing 96% ethanol and water and (2) supercritical extraction (SFE) by running carbon dioxide coupled with ethanol as a modifier. Higher phenolic concentrations of extracts were attained by SFE (∼400 ppm), doubling those obtained by SLE. In the latter, increasing values of both temperature (from 25 to 50 °C) and contact time (from 30 to 90 min) and lower solvent-to-solid ratios (from 5:1 to 1:1) resulted in an enhancement of extraction efficiency. In SFE, the addition of the modifier (8%) was also found to favour the release of phenolic compounds. Antiradical activity values—evaluated by the ability to scavenge DPPH radicals—were, as general, also higher for SFE extracts, although maximum values reached at were similar (73% inhibition versus 68%). Chromatographic profiles confirmed the diverse nature of phenolic species occurring in extracts obtained from both extraction methods. Extracts from SLE contained more proanthocyanidins, whereas SFE ones contained basically gallic acid, catechin and epicatechin. Protection against oil oxidation assayed with two samples confirmed these results.     

Microwave-assisted extraction of phenolic compounds from wine lees and spray-drying of the extract

Most research on extraction of phenol compounds from wine by-products and commercial exploitation of extracts use grape seeds and/or skins as raw materials. Looking for alternative antioxidants sources, obtaining antioxidant extracts from wine lees (also known as dregs), a sub-exploited by-product of winemaking process, is here presented. Microwave-assisted extraction (MAE) of phenolic compounds from wine lees has been optimized using the total phenols index, the ORAC values and yield of the extraction as response variables. Under the optimal working conditions, the proposed MAE method provides better extraction efficiency in a much shorter time (17 min) than the conventional extraction method for phenolic compounds (24 h). The liquid extract obtained by MAE was spray-dried. The type and amount of excipients used, as well as the spray-drying temperature, were optimized in order to minimize the oxidation of phenolic compounds and maximize the yield of the spray-drying process. The total phenols index in the dried extract thus obtained was 36.8% (expressed as gallic acid), showing an ORAC value of 3930 μmol TE/g. Additionally, Mv3G, Cm-Mv3G, myricetin, quercetin, quercetin-3-β-glucoside, caffeic acid and p-coumaric acid were quantified in the dry extract by HPLC–DAD. The results indicate that wine lees antioxidant extracts can be a suitable and cheap alternative to those obtained from grape seeds or skins.     

Unravelling scientific research towards the green extraction of phenolic compounds from leaves: a bibliometric analysis

Phenolic compounds (PCs) have been finding increasing applications in functional foods, cosmetic, pharmaceutical and nutraceuticals due to their nutritional and antioxidant properties. Considering the drawbacks of conventional extraction methods, there is an ongoing challenge for researchers to develop green extractions (GE) of PCs in a sustainable and eco-friendly way. A bibliometric study is a valuable tool to provide quantitative information for evaluating the scientific research activity based on the available published scientific literature. This bibliometric study aims for the first time to unravel the scientific exploration towards the GE of phenolics from plant by-products, that is, leaves by focussing on scientific publications collected through the Web of Science database. Consequently, insights into the evaluation of publication trends, authors, countries, organisations, keywords, journals, publishers and citations in support of GE were established. The critical evaluation of the results showed an increase in research, during the last decade, on GE of PCs from leaves. The study also revealed Europe as the leader in terms of publications, citations, countries, organisations, as well as authors contributing to this research topic. Following the analysis, directions for future research have also been suggested.     

基于主成分分析与聚类分析综合评价不同菌种发酵刺梨果渣的香气品质

采用顶空固相微萃取结合气质联用（HP-SPME-GC-MS）技术分别对嗜酸乳杆菌（Lactobacillus acidophilus）GIM.1.208、戊糖乳杆菌（Lactobacillus pentosus）CICC.22210、生香酵母和醋酸杆菌（Acetobacter pasteurianus）AS1.41 GIM.1.67发酵刺梨果渣后的香气成分进行分析,通过主成分分析（PCA）与聚类分析（CA）对香气成分进行判定、区分和聚集,并建立香气品质评价模型。结果表明：刺梨原果渣及发酵果渣中共检测出110种香气成分,主要为烃类（35种）、醇类（19种）、酯类（15种）、酸类（6种）、醛类（18种）、酮类（9种）、其他类（8种）。PCA结果表明,醇类和酯类是区分不同菌种发酵刺梨果渣的香气的主要因素。CA结果表明,原果渣与发酵果渣风味轮廓不同,说明经过不同菌种发酵后,刺梨果渣风味改变显著。通过建立香气品质评价模型,GIM.1.67组刺梨果渣综合得分最高（0.933分）,该模型评价结果与感官评价结果具有较好的一致性。     

近红外技术对不同动物来源肉掺假的检测

采用近红外光谱结合主成分分析法(PCA)、判别分析法,分别建立了牛肉和羊肉中掺杂其它动物肉的定性鉴别模型,根据鉴别准确率评价模型的预测性能。采用近红外光谱结合PCA、偏最小二乘法(PLS),建立了掺假物的定量检测模型,根据模型对预测集样品的预测均方差(RMSEP)以及预测值与实测值间的相关系数(r)验证模型的预测能力。结果,牛肉掺猪肉模型对训练集和预测集的鉴别准确率分别为97.86%和91.23%,羊肉掺猪肉模型对训练集和预测集的鉴别准确率分别为98.28%和92.98%,羊肉掺鸭肉模型对训练集和预测集的鉴别准确率分别为99.59%和93.97%,羊肉掺假模型对训练集和预测集的鉴别准确率分别为97.57%和90.76%。牛肉掺假定量模型对训练集的交互验证均方差(RMSECV)和预测集的RMSEP分别为3.87%和4.13%,r分别为0.9505和0.9134;羊肉掺假定量模型对训练集的RMSECV和预测集的RMSEP分别为4.48%和4.86%,r分别为0.9306和0.9082。表明近红外技术结合一定的化学计量学方法可实现不同动物来源肉掺假的鉴别,且能够对掺假物进行定量检测。