Concentration of flavonoids and phenolic compounds in aqueous and ethanolic propolis extracts through nanofiltration

Propolis has a variable and complex chemical composition with high concentration of flavonoids and phenolic compounds present in the extract. The extract varies with the solvent used in extraction. Ethanol extracts more phenolic acid and polar compounds than water. Before their use in industry, extracts must be concentrated but the use of high temperatures can degrade some compounds. Membrane processes is an option that allows concentration at low temperatures. Nanofiltration was carried out with aqueous and ethanolic extracts and each extract results in two distinct fractions: permeate and retentate. The capacity of the membrane to retain the compounds was verified by spectrophotometric analysis: for aqueous solution, the membrane retained around 94% of the phenolic compounds and 99% of the flavonoids, while for the ethanolic solution these values were 53% and 90%, respectively. Ferulic acid retention index was 1.00 and 0.88 to aqueous and ethanolic solutions, respectively. Thus, the nanofiltration process showed high efficiency in the concentration of propolis extracts.     

Water at room temperature as a solvent for the extraction of apple pomace phenolic compounds

A fractionation method was used to extract phenolic compounds from apple pomace (AP) involving a first extraction with water and subsequent extractions of the same residue with two different organic solvents. The water extracts obtained contained high amounts of phenolic compounds with high antioxidant capacity. However, the second and third extractions of the same residue still extracted considerable amounts of remaining phenolic compounds, both with significant antioxidant capacities. Liquid chromatography-electrospray ionisation mass spectrometry (LC-ESI/MS) studies showed water to be a good solvent to extract hydroxycinnamic acids, flavonols, flavanols, dihydrochalcones and flavones present in the AP. However, water was not the ideal solvent to extract the quercetin glycosides.     

A new process for the combined recovery of pectin and phenolic compounds from apple pomace

A process for the combined recovery of pectin and phenolic compounds from apple pomace, the primary by-product of apple juice production, was developed. The process includes extraction of dried apple pomace with diluted mineral acid and adsorption of phenolic constituents by a hydrophobic styrene–divinylbenzene copolymerisate. After elution with methanol, the polyphenolics were concentrated in vacuo, stabilised by lyophilisation, and characterised by high-performance liquid chromatography. The predominant compounds were phloridzin, chlorogenic acid and quercetin glycosides. Adsorptive removal especially of oxidised phenolic compounds led to a considerable decolourisation of the pomace extracts, as revealed by determination of L*a*b* values, hue angle and chroma. Gelling properties of pectin were not adversely affected. While the polyphenolics recovered from apple pomace may be used as natural antioxidants or as functional food ingredients, extended fields of application may be obtained for decolorised, refined apple pectins. Furthermore, investigations on the phenolic composition of several New Zealand apple cultivars, of apple seeds, and on the effects of pomace drying on the stability of polyphenolics were carried out.     

Characterisation of phenolic extracts from olive pulp and olive pomace by electrospray mass spectrometry

Methanol extracts of olive pomace (two‐phase olive oil extraction) and olive pulp were analysed by reverse phase HPLC and the eluted fractions were characterised by electrospray ionisation mass spectrometry. This technique allowed the identification of some common phenolic compounds, namely, verbascoside, rutin, caffeoyl‐quinic acid, luteolin‐4‐glucoside and 11‐methyl‐oleoside. Hydroxytyrosol‐1′‐β‐glucoside, luteolin‐7‐rutinoside and oleoside were also detected. Moreover, this technique enabled the identification, for the first time in Olea europaea tissues, of two oleoside derivatives, 6′‐β‐glucopyranosyl‐oleoside and 6′‐β‐rhamnopyranosyl‐oleoside, and of 10‐hydroxy‐oleuropein. Also, an oleuropein glucoside that had previously been identified in olive leaves was now detected in olive fruit, both in olive pulp and olive pomace. With the exception of oleoside and oleuropein, the majority of phenolic compounds were found to occur in equivalent amounts in olive pulp and olive pomace. Oleoside was the main phenolic compound in olive pulp (31.6 mg g^?1) but was reduced to 3.6 mg g^?1 in olive pomace, and oleuropein (2.7 mg g^?1 in the pulp) almost disappeared (<0.1 mg g^?1 in the pomace). Both these phenolic compounds were degraded during the olive oil extraction process. Copyright © 2004 Society of Chemical Industry     

Determination of simple sugars,malic acid and total phenolic compounds in apple pomace by infrared spectroscopy and PLSR

The aim of this work was to develop a fast, versatile, inexpensive and environmentally safe analytical method to quantify simple sugars, malic acid and total phenolic compounds in apple pomace, considering its potential use as a raw material with value instead of as an industrial waste. Diffuse reflectance infrared spectroscopy (DRIFTS) measurements of twenty‐six samples of apple pomace were analysed by partial least squares regression (PLSR), using several signal pre‐processing methods. Multivariate models developed with four to five latent variables (LVs) and based in the MIR (mid‐infrared) region had good prediction for the determination of sucrose, fructose, malic acid and total phenolic compounds, with average errors between 3.9% and 6.6%. By contrast, glucose was better determined by models developed in the NIR (near‐infrared) region and using six LVs, yielding an average error lower than 7.4%. These results confirmed the feasibility of the multivariate spectroscopic approach as an alternative for expensive and time‐consuming conventional chemical methods.     

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%).     

Concentration and purification of galacto‐oligosaccharides using nanofiltration membranes

This study was aimed at using nanofiltration to purify the galactooligosaccharides (GOS) found in a commercial mixture containing lactose, glucose and galactose, whose compositions were similar to that obtained through transgalactosylation reactions catalysed by β‐galactosidase from Kluyveromyces marxianus CCT 7082. NP030 polyethersulphone membrane was selected for the purification processes, once it differed statistically from other membranes due to the higher purification factor and permeate flux under the optimised temperature and pressure conditions of 35 °C and 3 MPa, respectively. Results indicate that NP030 membrane can be employed as a preliminary technique for the GOS purification with approximately 61% (w/w) of recovery.     

Industrial clarification of anthocyanin‐rich grape pomace extracts by crossflow membrane filtration

A comparative study on the clarification of anthocyanin‐rich grape pomace extracts was carried out by tubular, hollow fibre and spiral wound industrial crossflow membrane units. Three polysulfone membranes were tested: a 500‐kDa molecular mass cut‐off (MMCO), and a 0.2‐ and 0.6‐μm pore size cut‐offs (PSCO). The 500‐ kDa MMCO and the 0.2‐μm PSCO membranes produced particle‐free extracts, while the 0.6‐μm membrane showed deficient clarification. The 500‐kDa MMCO membrane produced up to 3.7% loss of most of the individual anthocyanins, while the 0.6‐ and 0.2‐μm PSCO membranes produced up to 2% only of some of the anthocyanins with higher molecular masses. Permeate steady fluxes of up to 53 L h^?1 m^?2 were obtained. Particles with sizes of 0.5–1.5 μm and the macromolecular anthocyanin–tannin complexes had a major impact on membrane performance. The obtained results are scalable to industrial installations.     

响应面法优化超声波辅助提取苹果渣低聚糖的工艺

以苹果渣为原材料,在单因素实验的基础上,通过Box-Behnken实验设计以及响应面分析法,研究超声时间、料液比、乙醇体积分数和超声温度对苹果渣低聚糖得率的影响。优化后的最佳工艺参数为超声时间35 min、料液比1∶17（g/m L）、乙醇体积分数80%、超声温度43℃,在此实验条件下,苹果渣低聚糖实际得率为13.23%。结果表明,响应面分析法对超声波辅助提取苹果渣低聚糖的工艺优化合理可行,为其开发利用提供了理论支持。      

太空诱变复合菌剂发酵苹果渣生产菌体蛋白的研究

试验利用太空诱变获得的优良菌种一黑曲霉ZM-8和啤酒酵母、热带假丝酵母以及白地霉复配制成复合菌剂,固体发酵苹果渣,得到的菌体蛋白中纤维素含量降低,粗蛋白含量显著提高,营养价值增加.通过正交试验获得了最适的培养基配方和复合菌剂的最佳配方.试验确定的最适培养基配方为白糖4g,硫铵7g,尿素1g,食盐2g,产物中粗蛋白的含量达26.4%,提高了306.3%.复合菌剂的最佳配方为黑曲霉突变株ZM-8(Asp.niger ZM-8)1.5g,酿酒酵母(Saccharomyces cerevisiae)0.5g,热带假丝酵母(Candida tropicalis)1.0g,白地霉菌(Gcotrichum candidum)0.5g,产物中粗蛋白的含量达27.9%,提高了337.5%.     

High‐pressure high‐temperature extraction of phenolic compounds from grape skins

This study focused on the use of a non‐conventional extraction technology by employing high‐pressure high‐temperature stirred reactor to extract polyphenols from grape skins. Extraction time (15–330 min) and temperature (30–150 °C) were selected as independent variables, and their effects were studied. A preliminary kinetic study on polyphenols extraction revealed that the second‐order model fitted satisfactorily the experimental results (R² ≥ 0.9798). Total polyphenol yield and total flavonoid (TF) yield, as well as the antiradical power (ARP) of the extracts, were analysed. The use of high‐pressure high‐temperature technology resulted in obtaining extracts rich in polyphenols with high ARP. The highest total polyphenol (60.7 mg_GAE ) and TF (15.1 mg_CE ) yields were obtained at 150 °C for 270 min and 150 °C for 15 min, respectively. HPLC was employed to analyse phenolic compounds. Considerable quantities of single phenolic compounds were extracted. The highest yields of gallic acid, 5‐hydroxymethylfurfural, protocatechuic acid, catechin, vanillic acid, syringic acid, cumaric acid, trans‐resveratrol and quercetin (163.2, 20.0, 69.9, 420.0, 20.6, 603.0, 20.1, 42.4 and 117.1 mg per 100 g_DS, respectively) were found. ARP values were found between 8.45 and 52.17 μg_DPPH .     

Development of a green innovative semi-industrial scale pilot combined microwave heating and centrifugal force to extract essential oils and phenolic compounds from orange peels

A new process for extraction of essential oils from orange peels (Citrus sinensis L.) using microwave and centrifugal (MW/C) force was studied. MW/C is a combination of microwave heating to explode the internal cells of biological material, and centrifugation to intensify diffusion, collection and separation of compounds of interest. MW/C is performed at atmospheric pressure with an injection of water vapor. A detailed study concerning optimization of different operating parameters like microwave power density and centrifugation was performed. MW/C has been compared to the hydrodistillation method. In addition of essential oils collection, in the aqueous phase several phenolic compounds can be obtained and valorized. Influence of the two main parameters was discussed first on essential oils and, in second part, on phenolic compounds recovery. The new combined MW/C process provided reduction in the extraction time compared to hydrodistillation method, with an advantage to collect in a same experiment volatile and nonvolatile compounds with high quality.Industrial relevanceThis work was carried out thanks to the investment of IFTS France, an international technical center worldwide known in the field of solid-fluid separations. Considering the huge amount of plant extracts this new combined system using microwave and centrifugal (MW/C) force may be suitable for scaling up. The results of this investigation on pilot reactors pave the way for the design of an industrial device.     

Effects of gamma radiation on the phenolic compounds and in vitro antioxidant activity of apple pomace flour during storage using multivariate statistical techniques

The aim of this study was to evaluate the effects of gamma radiation on the phenolic compounds and antioxidant activity of apple pomace flour (0, 1 and 2 kGy dose at times of 0, 3, 6 and 9 months) during storage using multivariate techniques. The a* and h° colour attributes at a dose of 1 kGy, and the phenolic compound phloridzin showed constant levels during the experiment. The dose of 1 kGy at time 0 provides better results for antioxidant activity, total phenolic compounds and some individual compounds. Chlorogenic acid and its class of hydroxycinnamic acids increased proportionally with time in the irradiated samples. The chemometric approach made it possible to observe the influence of irradiation and storage time on the samples of apple pomace flour. The effect of irradiation on the phenolic compounds was related to the intensity and the characteristics of each individual compound.Industrial relevanceIrradiation has been shown to be an economically viable alternative for the treatment of foods; it has several advantages compared to traditional processing methods and can be applied independently or combined with existing techniques such as dehydration. Thus, this combination of treatments, as well as increasing the shelf life of apple pomace also increases the concentrations of nutrients and can be applied in the pharmaceutical, cosmetics and food industries. This advantage can translate into economic advantages, with added values in various applications and help to partially reduce negative impacts on the environment.     

Concentration of biologically active compounds extracted from Ilex paraguariensis St. Hil. by nanofiltration

The aim of this study was to characterise the bioactive compounds in mate (Ilex paraguariensis St. Hil) extract and in concentrated mate extract obtained by nanofiltration (NF). Also, the impact of NF on the antioxidant activity of both mate extracts was evaluated in vitro and using eukaryotic cells of Saccharomyces cerevisiae (yeast assay). The results showed a significant increase in the contents of total phenolics (338%), chlorogenic acid (483%), theobromine (323%), caffeine (251%), chlorophyll (321%), condensed tannins (278%) and saponins (211%) in the concentrated mate extract. The concentrated mate extract showed higher in vitro antioxidant activity than the mate extract. According to the results obtained, it can be stated that the use of nanofiltration membrane is a valid approach for the concentration of biologically active compounds in aqueous extract of mate.     

酸法提取苹果渣中的果胶及其性质分析

采用酸法提取苹果渣中的果胶,并以单因素试验为基础,通过响应面法优化其提取工艺条件。结果表明,酸法提取苹果渣果胶的最佳工艺条件为：盐酸调节pH值1.5,温度100 ℃,时间2 h,固液比1∶14（g∶mL）。在上述最佳条件下,苹果渣中粗果胶得率为33.12%,果胶提取率为19.65%。4个因素对粗果胶得率的影响顺序为：pH值＞温度＞时间＞固液比。酸法提取果胶的分子质量主要分布在165.92 kDa、5.83 kDa与0.45 kDa范围;酯化度为60.90%,属于高酯果胶;半乳糖醛酸含量为70.48%,所提取的果胶纯度相对较高。     

高效液相色谱-二极管阵列联用技术同时检测苹果醋和甘蔗醋中11种酚类物质

利用高效液相色谱联合二极管阵列技术（HPLC-DAD）建立一种可以同时检测不同苹果醋和甘蔗醋中11种酚类物质的分析方法。使用OMNI Hubble C₁₈色谱柱（250 mm×4.6 mm,5μm）,流动相A为甲醇-甲酸（100∶2,v/v）,B为10 mmol/L磷酸氢二钾-磷酸水溶液（200∶1,v/v）,流速为1.0 m L/min,进样量为20μL,梯度洗脱,柱温为35℃,二极管阵列扫描波长范围210⁴00 nm。应用本方法可以检测出不同苹果醋和甘蔗果醋中香草醛、香豆素、绿原酸、咖啡酸、阿魏酸、对香豆酸、芹菜素、木犀草素、肉桂酸、山奈酚、芒柄花黄素等11种酚类物质,其中甘蔗醋中富含绿原酸等10种酚类物质成分。本方法回收率在84.1%¹18.2%之间,结果准确可靠,简单易行,适合用于各类果醋中酚类物质的分析检测。      

Total phenolic compounds,radical scavenging and metal chelation of extracts from Icelandic seaweeds

Screening of potential antioxidant activities of water and 70% acetone extracts from ten species of Icelandic seaweeds was performed using three antioxidant assays. Significant differences were observed both in total phenolic contents (TPC) and antioxidant activities of extracts from the various species evaluated using 2,2-diphenyl-1-picrylhydrazyl (DPPH) radical scavenging activity, oxygen radical absorbance capacity (ORAC) and ferrous ion-chelating ability assays. Acetone extracts from three Fucoid species had the highest TPC and consequently exhibited the strongest radical scavenging activities. High correlation was found between TPC of seaweed extracts and their scavenging capacity against DPPH and peroxyl radicals, indicating an important role of algal polyphenols as chain-breaking antioxidants. However, water extracts generally had higher ferrous ion-chelating activity than 70% acetone extracts and no correlation was found with their TPC, suggesting that other components such as polysaccharides, proteins or peptides in the extracts were more effective chelators of ferrous ions than phenolic compounds.