Impact of saccharides and amino acids on the interaction of apple polyphenols with ion exchange and adsorbent resins

Model solutions containing catechin, caffeic acid, chlorogenic acid, phloridzin and rutin were used to examine their recovery using two adsorbent resins, four cation and four anion exchange resins at two temperatures (20 °C and 40 °C) and two pH values (pH 1 and 7). In addition, the interference of glucose, fructose and sucrose and of a saccharide mixture on polyphenol binding by one anion exchange and two adsorbent resins was assessed to approximate real conditions. In a further step polyphenol recovery using the aforementioned adsorbent and ion exchange resins was studied upon the addition of the amino acids alanine, glutamic acid, phenylalanine, lysine and histidine. The data reveal that both saccharides and amino acids influence polyphenol recovery positively and negatively, depending on the experimental conditions and the resin type; possible explanations for these findings are discussed. The information obtained in this study helps to gain a better understanding of the complex mechanisms of ion exchange and adsorption processes involving multi-component systems. The insights gained allow to design cost-efficient recovery of plant secondary metabolites from crude extracts for producing tailor-made health-beneficial fractions.     

Enrichment and fractionation of major apple flavonoids, phenolic acids and dihydrochalcones using anion exchange resins

In the present study model solutions containing isolated apple polyphenols were employed to systematically study their interaction with two strong anion exchangers differing in the structure of their polymeric matrix. Equimolar concentrations of catechin, caffeic acid, 5-O-caffeoylquinic acid (chlorogenic acid), phloridzin and rutin were used in single compound, binary, ternary, quaternary and pentenary model systems to investigate their ion exchange and adsorption behavior when brought into contact with a polystyrene-divinylbenzene-based and a polyacrylamide-based ion exchanger resin in a column system. To enhance differentiation between adsorption phenomena involving the lipophilic backbone of the exchanger resin and ion exchange processes, experiments were performed at pH 1 and 7. The results of this study allow a deeper insight into the complex processes occurring upon ion exchange. Significant differences were found using the two ion exchangers with the polystyrene resin showing higher recovery rates indicating that the polymeric backbone also markedly contributes to polyphenol binding through hydrophobic interactions. Furthermore, resin selectivity with regard to the binding of phenolic compounds was also shown to be dependent on the structure of the exchanger matrix. These results may further contribute to improve industrial processes for the cost-efficient and selective recovery of secondary plant metabolites, thus allowing to systematically manipulate the biofunctional properties of plant extracts.     

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.     

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.     

Solid-state fermentation of apple pomace using Phanerocheate chrysosporium – Liberation and extraction of phenolic antioxidants

Apple pomace is a by-product from the apple processing industry and can be used for the production of value-added phenolic compounds. A study was carried out to understand the changes and liberation of phenolic compounds and improvement in antioxidant activity during solid-state fermentation of apple pomace using Phanerocheate chrysosporium. The solid-state fermentation of apple pomace using P. chrysosporium mobilised the polyphenolic compounds and improved the nutraceutical properties. The polyphenol content in acetone extract increased and the results were statistically significant (P < 0.05) from 4.6 to 16.12 mg GAE/g dry weight during solid-state fermentation. The effect of various solvents, temperature, time and detergents were also investigated for the extraction of polyphenolics by ultrasonication and microwave-assisted extraction methods. The polyphenol content of the extracts was found to be in the range of 5.78–16.12 mg GAE/g DW of samples, depending on the solvent, extraction time and temperature. Antioxidant activities of polyphenol extracts were tested using the 2,2-diphenyl-1-picryhydrazyl (DPPH) radical methods, where the IC₅₀ ranged from 12.24 to 23.42 μg DW sample, depending on the extraction conditions and the antioxidant activities correlated well with the polyphenol concentrations.     

Sustainable sunflower processing — II. Recovery of phenolic compounds as a by-product of sunflower protein extraction

A process for the recovery of polyphenol-rich extracts from the production of light colored sunflower protein isolates by combining mild-acidic protein extraction with adsorptive removal of phenolic compounds has been developed. In preliminary trials, different solvents were examined to evaluate their suitability for an exhaustive desorption of the polyphenols from a food-grade adsorbent resin. For this purpose, the elution behavior of different solvent–water mixtures was assessed at identical temperatures and flow rates. Besides methanol and ethanol, 2-propanol showed the most promising results. Furthermore, a D-optimal experimental design was applied to further optimize desorption of phenolic compounds from the adsorbent resin. Optimal conditions were deduced from experiments performed at different temperatures and flow rates and with varying solvent concentrations also evaluating the phenolic compound profiles at each step of the recovery process. Finally, antioxidant capacity of the polyphenol-enriched eluates was determined using the Folin–Ciocalteu and FRAP (ferric ion reducing antioxidant power) assays with ascorbic acid and trolox, respectively, as reference compounds.Industrial relevanceProtection against oxidation is a major challenge for the retention of sensory quality of processed foods. Since consumers generally reject artificial food additives, their substitution by natural counterparts is of increasing relevance. Phenolic compounds of different plant sources such as grape and apple pomace are known as potent antioxidants and radical scavengers. Consequently, to achieve sustainability of sunflower processing and complete utilization of by-products arising from sunflower oil production, polyphenols co-extracted during sunflower protein recovery from the expeller were recovered by adsorption technology. After their exhaustive desorption from the adsorber resin, the polyphenol enriched eluate may be used as a natural antioxidant due to its high antioxidant activity as demonstrated by this study.     

苹果枝条多酚分离纯化及其抗氧化活性研究

研究了6种大孔树脂对苹果枝条多酚的吸附性能,筛选出分离苹果枝条多酚的最佳树脂为X-5,进一步研究X-5大孔树脂纯化多酚的工艺条件和技术参数。所得最佳纯化工艺为:上样浓度为1mg/m L,流速为1.0BV/h,pH5.0,以70%乙醇溶液为洗脱剂,洗脱流速为2.0BV/h。在此条件下,所得苹果枝条多酚的纯度为72.36%,提取率为0.82%。对纯化后的苹果枝条多酚抗氧化活性进行研究,结果表明:苹果枝条多酚具有较强的还原能力,对羟基自由基、DPPH自由基具有良好的清除能力。      

响应曲面分析法优化苹果渣中多酚类物质的果胶酶辅助提取工艺

研究了响应面分析法对苹果渣中多酚类物质的果胶酶辅助提取工艺。以总多酚、咖啡酸提取量为评价指标,在单因素实验基础上根据中心组合实验设计原理,采用3因素5水平的响应曲面分析法对提取工艺进行了优化。通过响应曲面实验及回归分析得出最佳工艺条件为：果胶酶,基质比O．11、反应温度38．00℃、反应时间12．53h。在此条件下,预测总多酚和咖啡酸提取量分别为11．32gGAE／kg和173．87mg／kg。经验证,总多酚和咖啡酸提取量分别达到11．08gGAE／kg和170．03mg／kg。另外,相对于对照组的6．78gGAE／kg和13．14mg／kg分别提高1．6倍和12．9倍。表明由响应曲面法获得的二次模型方程能较好地预测实验结果及优化条件：果胶酶辅助提取工艺稳定合理、准确可靠,是提取苹果渣中总多酚、咖啡酸的可行方法。     

Comparison of fining red wines with purified grape pomace versus commercial fining agents: effect on wine chromatic characteristics and phenolic content

The large quantity of grape pomace (seeds, skin, and peduncle) produced during the winemaking process can be a problem and the search for procedures which could permit their valorisation is considered an important issue. This study investigates the use of purified grape pomace as a fining agent for reducing the level of some wine phenolic compounds, especially tannins. For this, purified grape pomace was applied to three young red wines of different phenolic composition and the results were compared with the effect of some common commercial fining agents. The results demonstrated that grape pomace can be used to decrease the wine tannin content with similar results to those obtained with casein, while also reducing anthocyanin content although to a similar extent to when bentonite is used. The effect of purified Monastrell grapes pomace is similar in the three different studied wines although it affected the most to wines with high monomeric anthocyanin content.     

酿酒葡萄皮渣经贮存和红外干燥后的质量变化比较

本文研究了酿酒葡萄皮渣在未经干燥下的贮存过程中及其经红外干燥处理后的质量变化,一方面对其在存放过程中的质量变化进行分析,另一方面探究红外干燥处理酿酒葡萄皮渣的可能性。处理方式为将收集到的葡萄皮渣分别贮存0、1、3、5和7d后晒干,贮存1d的皮渣分别进行葡萄皮和葡萄籽超微粉碎处理,其余的只进行葡萄籽超微粉碎处理;取适量贮存1d的皮渣进行红外干燥并分别进行葡萄皮和葡萄籽超微粉碎处理。通过对超微粉的微生物(酵母菌、霉菌和细菌)、单体酚(8种)和真菌毒素(展青霉毒毒素和赭曲霉毒素)的含量变化进行检测分析,发现随着贮存时间的延长,酵母菌含量先升高后降低,霉菌和细菌以及真菌毒素含量均显著升高,各单体酚含量则显著降低;贮存1d后进行红外干燥处理的超微粉的微生物含量明显降低,说明红外干燥具有很好的灭菌效果,各单体酚有一定损失,而真菌毒素含量没有明显变化。综合考虑,酿酒葡萄皮渣收集后应立即进行干燥处理,红外干燥可以用于酿酒葡萄皮渣的干燥处理。      

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).     

Kinetics of ultrasonic extraction of polyphenols,anthocyanins and tannins from five different New Zealand grape pomaces

Polyphenols were extracted from five kinds of New Zealand grape pomace (Sauvignon Blanc, Pinot Gris, Gerwurztraminer, Merlot and Pinot Noir) at 30, 50 and 70 °C in an ultrasonic generator. The extraction kinetics for total phenol, anthocyanin and tannin were determined. The results of dynamics study showed that the extraction of total polyphenols, anthocyanin and tannin followed first-order reaction kinetics during the extraction at 30, 50 and 70 °C. The total phenolic content, anthocyanin conten, and tannin content of water–ethanol extracts from grape pomaces were compared, and the parameters in the extraction kinetics equations were determined. The extraction results showed that the Pinot Noir pomace extract had the highest total phenolic content of 59.95 mg GAE g⁻¹ pomace and tannin content of 79.93 mg EE g⁻¹ pomace. The anthocyanin content in Merlot pomace extract was the highest, which was 4.50 CE g⁻¹ pomace. The results might be of great significance for the development of grape pomace or its polyphenol and/or anthocyanin components as an antioxidant source with natural and inexpensive benefits.     

Sustainable sunflower processing — I. Development of a process for the adsorptive decolorization of sunflower [Helianthus annuus L.] protein extracts

A novel process for the production of light-colored sunflower protein isolates was developed, combining mild-acidic protein extraction with adsorptive removal of phenolic compounds. Four commercial food-grade adsorbent and three ion exchange resins were tested with regard to their affinity towards polyphenols. Amberlite™ XAD 16HP and FPX 66 showed optimal decolorization of the sunflower crude extracts. In contrast, ion exchange resins exerted maximal binding of monomeric phenolic compounds, but were less effective in removing colored compounds. Adsorption behavior of individual resins was assessed by adding resin to protein extracts varying the amounts of resin, protein concentration of the solutions and temperature. Furthermore, a D-optimal experimental design was applied to optimize adsorptive polyphenol removal from sunflower protein extracts using a styrene–divinylbenzene copolymer. Adsorption isotherms were determined for 5-O-caffeoylquinic acid and total phenolics, respectively. Optimal conditions were deduced from experiments at different temperatures, with different flow rates and extract concentrations. Finally, adsorbent and ion exchange resin columns were connected in series and successfully applied to produce light-colored sunflower protein on a pilot scale under the conditions optimized in laboratory experiments, thus demonstrating that this technology can easily be integrated into existing process lines.

Industrial relevance

A vital necessity to exploit novel protein sources arises from the increasing demand for human nutrition. Residues originating from sunflower oil production are rich in proteins and might serve as a source of plant proteins, which has not been valorized so far. This is due to their high contents of phenolic compounds that may interfere with the proteins lowering their nutritional value and impairing their sensory properties. Therefore, a process for mild-acidic protein extraction combining adsorption and ion exchanger technology for the removal of polyphenols from crude sunflower extracts was developed in the present study.     

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.     

Phenolic compounds and antioxidant activity of seed and skin extracts of red grape (Vitis vinifera and Vitis labrusca) pomace from Brazilian winemaking

The phenolic compounds content and antioxidant activity of seed and skin of pomace from the vinification of grape varieties widely produced in Brazil were investigated with a view to their exploitation as a potential source of natural antioxidants. There was a greater concentration of phenolic compounds in the seeds (2128 to 16,518 mg of catechin equivalents (CE)/100 g) than in the skins (660 to 1839 mg CE/100 g). The highest antioxidant activity values determined as DPPH radical-scavenging ability and ferric reducing-antioxidant power (FRAP) were found for the seeds of the Pinot Noir variety (16,925 ??mol Trolox equivalents (TE)/100 g and 21,492 ??mol Fe²⁺/100 g, respectively) and in the skin extracts of the Isabel variety (3640 ??mol TE/100 g and 4362 ??mol Fe²⁺/100 g, respectively). The skin of Cabernet Sauvignon and Primitivo varieties had the highest contents of anthocyanins (935 and 832 mg/100 g, respectively). The grape seed extracts were rich in oligomeric and polymeric flavanols. The data suggested that grape seed and skin extracts may be exploited as antioxidant agents.     

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.     

压榨对酿酒葡萄皮渣酚类物质提取及抗氧化活性的影响

酿酒葡萄皮渣（皮和籽）生物活性物质含量丰富,具有很高的再加工利用价值。对鲜葡萄皮渣进行压榨处理后再干燥,研究压榨对皮渣的酚类物质提取及抗氧化活性的影响。结果表明：压榨处理可以快速降低葡萄皮渣水分含量,缩短干燥时间、提高可溶性膳食纤维提取率。压榨葡萄皮总酚、原花青素的提取量均有所增加,其含量分别为19.56 mg/g和22.64 mg/g。压榨葡萄皮的抗氧化能力高于未压榨葡萄皮,其DPPH、ABTS及羟自由基清除率分别为62.90%、70.18%和41.09%,铁氰化钾还原能力及金属离子螯合能力分别为0.23%和21.33%。压榨籽和皮籽混合物的酚类物质和抗氧化活性则明显降低。抗氧化活性与总酚、原花青素存在显著的相关关系（P＜0.01）。     

Phenolic profiles,antioxidant activity and in vitro antiviral properties of apple pomace

Methanolic and acetonic extracts of apple pomace were evaluated for phenolic profiles, antioxidant properties and antiviral effect against herpes simplex virus type 1 (HSV-1) and 2 (HSV-2). Acetone extraction yielded the higher amounts of phenolic compounds. The extraction method influenced the phenolic composition although antioxidant activity correlated weakly with phenols concentration. Among the polyphenols analysed, quercetin glycosides were the most important family, followed by dihydrochalcones. Apple pomace extracts were able to inhibit both HSV-1 and HSV-2 replication in Vero cells by more than 50%, at non-cytotoxic concentrations. Selectivity indexes (SI) ranged from 9.5 to 12.2.     

Recovery of anthocyanins from grape pomace extracts (Vitis vinifera L. cv. Cabernet Mitos) using a polymeric adsorber resin

Anthocyanins from a Cabernet Mitos grape pomace were extracted without sulfitation, purified and concentrated on a laboratory scale by adsorption to a styrene–divinylbenzene copolymerisate. The pigment loss during sample loading and washing of the column with water was negligible. Elution was performed with acidified methanol, ethanol and 2-propanol, respectively. The recovery rates ranged from 96 to 100% of anthocyanins when methanol was used, from 86 to 96% for ethanol and from 78 to 88% when pigments were eluted with 2-propanol. The temperature during adsorption and desorption (25 and 50 °C) did not significantly influence the pigment binding capacity. The recovery rates were not affected by the scale-up from laboratory to pilot-plant adsorption experiments. The use of polymeric resins facilitates nonthermal anthocyanin concentration since highly pigmented alcoholic eluates were obtained which can further be concentrated under mild conditions. The present study provides systematic data on adsorber technology increasingly used for the recovery of plant secondary metabolites.     

Adsorptive recovery of phenolic compounds from apple juice

The recovery of phenolic compounds from apple juice was studied on a laboratory scale using a food grade polymethylmethacrylate adsorption resin. The work was carried out to understand how the processing parameters of the adsorption process can be manipulated to optimise production of apple phenolics as functional food ingredients. Adsorption was determined by mixing weighed amounts of the polymer with a diluted apple juice concentrate at 20–80 °C and at pH values ranging from 2.0 to 3.9. At regular intervals samples were withdrawn from the aqueous phase. Total phenolics, absorbance values at 280 and 420 nm, and the amounts of individual phenolics remaining in the liquid phase were determined. The analytical data were fitted to the Langmuir and Freundlich isotherms. In contrast to previous findings, the pH value significantly affected the adsorption onto the resin. HPLC analyses revealed different affinities of individual compounds, which enabled selective enrichment of certain phenolics in the liquid phase or on the sorbent surface. Desorption studies were performed using a resin with known amounts of adsorbed phenolic compounds. Elution was carried out by an automated pressurised liquid extraction system, studying the effects of temperature (40–180 °C) and solvents (water, ethanol, methanol). Here again, individual compounds showed different behaviours depending on their hydrophobicity. Therefore, a systematic change of parameters for the sorption and desorption process can be helpful for the recovery of purified plant extracts enriched in certain target compounds.