Protective effects of sweet orange (Citrus sinensis) peel and their bioactive compounds on oxidative stress

Protective effects of sweet orange (Citrus sinensis) peel and their bioactive compounds on oxidative stress were investigated. According to HPLC-DAD and HPLC-MS/MS analysis, hesperidin (HD), hesperetin (HT), nobiletin (NT), and tangeretin (TT) were present in water extracts of sweet orange peel (WESP). The cytotoxic effect in 0.2 mM t-BHP-induced HepG2 cells was inhibited by WESP and their bioactive compounds. The protective effect of WESP and their bioactive compounds in 0.2 mM t-BHP-induced HepG2 cells may be associated with positive regulation of GSH levels and antioxidant enzymes, decrease in ROS formation and TBARS generation, increase in the mitochondria membrane potential and Bcl-2/Bax ratio, as well as decrease in caspase-3 activation. Overall, WESP displayed a significant cytoprotective effect against oxidative stress, which may be most likely because of the phenolics-related bioactive compounds in WESP, leading to maintenance of the normal redox status of cells.     

Determination of phenolic composition and antioxidant capacity of blood orange juices obtained from cvs. Moro and Sanguinello (Citrus sinensis (L.) Osbeck) grown in Turkey

The phenolic compounds and antioxidant capacities of orange juices obtained from cvs. Moro and Sanguinello (Citrus sinensis (L.) Osbeck) were determined. A high-performance liquid chromatographic method coupled with diode-array detection was used to identify and quantify phenolic compounds of the orange juices. A total of 18 phenolic compounds were identified and quantified in Moro and Sanguinello orange juices, including hydroxybenzoic acids (2), hydroxycinnamic acids (5), flavanones (5), and anthocyanins (6). It was observed that total phenolic content of Moro juice was higher than that of Sanguinello juice. Ferulic acid was the most dominant hydroxycinnamic acid and cyanidin 3-(6″-malonyl glucoside) and cyanidin 3-glucoside were the most dominant anthocyanins in both cultivars. Antioxidant activities of orange juices were measured using the DPPH^· (2,2-diphenyl-1-picrylhydrazyl) method. According to DPPH^· assays, the antioxidant capacity of Moro juice was found to be higher than that of Sanguinello juice.     

超声波辅助提取菠萝皮多酚物质的研究

研究了超声波辅助提取菠萝多酚物质的工艺,对影响多酚浸提率的因素进行了单因素试验和正交试验,确定了最佳工艺条件为:乙醇浓度60%,浸提温度45℃,功率200W,浸提时间60min,液料比15.0∶1.0。在此条件下,浸提率可达18.48g/kg。     

Enhanced extraction of flavanones hesperidin and narirutin from Citrus unshiu peel using subcritical water

Flavanones including hesperidin and narirutin constitute the majority of the flavonoids that occur naturally in citrus fruits. The main purpose of this study was to extract valuable natural flavanones from agricultural by-products such as citrus peels using subcritical water extraction (SWE). Thus, the application of SWE to extraction of flavanones hesperidin and narirutin from Citrus unshiu peel was evaluated, and the effect of key operating conditions was determined by varying the extraction temperature (110–200 °C) and time (5–20 min) under high pressure (100 ± 10 atm). The maximum yields of hesperidin (72 ± 5 mg/g C. unshiu peel) and narirutin (11.7 ± 0.8 mg/g C. unshiu peel) were obtained at an extraction temperature of 160 °C for an extraction time of only 10 min. These yields accounted for approximately 99% of the total amount of these flavanones in the original material. The SWE was compared with three conventional extraction methods in terms of the extraction time and recovery yields for hesperidin and narirutin. The hesperidin yield by SWE was more than 1.9-, 3.2-, and 34.2-fold higher than those obtained by extraction methods using ethanol, methanol, or hot water, respectively, and the narirutin yield was more than 1.2-, 1.5-, and 3.7-fold higher.     

微波辅助提取苹果皮中的多酚类物质

以苹果皮为原料提取苹果多酚,对不同提取剂的提取效果进行了比较;通过单因子试验和正交试验对微波辅助提取多酚的工艺条件进行了探讨,研究了溶剂浓度、微波功率、微波处理时间以及料液比对多酚提取的影响;并对微波辅助提取和常规法提取的效果进行了比较。结果表明：综合考虑提取效果及食品安全性,选择乙醇作为提取剂为宜;微波辅助提取的最佳工艺条件为乙醇浓度70%、微波功率210W、微波时间25s、料液比（w/v）1∶5;微波辅助提取法提取物中原花色素含量0.3668mg/ml,常规法提取物中原花色素含量0.2552mg/ml,微波辅助提取效果优于常规法提取。     

超声波提取橘皮中柠檬苦素化合物的工艺研究

研究了超声波法从温州蜜柑果皮中提取柠檬苦素化合物的工艺,探讨溶剂种类及浓度、料液比、超声时间、提取温度对柠檬苦素化合物提取率的影响。通过正交实验确定其最佳提取工艺条件为:65%乙醇溶液、料液比1:30(g/mL)、超声18min、提取温度60℃,提取率为6.25mg/g。     

酶法制取橙皮果胶的研究

纤维素酶酶系组成复杂,不同来源纤维素酶在果胶提取中表现出的作用不同。采取与前人研究不同的纤维素酶对橙皮果胶进行提取,对三种不同来源的纤维素酶比较分析,筛选出一种价格低廉、适合果胶提取的纤维素酶,并采用四元二次通用旋转组合设计方法研究了其提取果胶工艺中缓冲溶液的pH、提取时间、酶添加量、提取温度对果胶得率的影响;建立数学模型,寻求测定条件的最优组合;以DesignExpert软件进行分析,模型经检验差异显著,失拟检验不显著,具有良好的统计学意义,最优组合为:酶添加量3.38mL、时间6.66h、温度47.5℃、pH4.95,预测模型果胶得率为14.43%,验证实验得率为14.79%,大大提高了纤维素酶制取果胶的得率,远远高于文献报道,并且酶的价格低廉,大大降低了生产成本。     

Antioxidant and antiproliferative activities of mango (Mangifera indica L.) flesh and peel

The antioxidant and antiproliferative properties of flesh and peel of mango (Mangifera indica L.) were investigated. The cytoprotective effect of mango flesh and peel extracts on oxidative damage induced by H₂O₂ in a human hepatoma cell line, HepG2, were determined, and the underlying mechanism was examined by a single-cell electrophoresis assay (comet assay). Treatment of HepG2 cell with mango peel extract prior to oxidative stress was found to inhibit DNA damage. The free radical scavenging activities of mango flesh and peel extracts were evaluated by electron spin resonance (ESR). The mango peel extract exhibited stronger free radical scavenging ability on 1,1-diphenyl-2-picrylhydrazyl (DPPH) and alkyl radicals than mango flesh extract, regardless of ripeness. Similarly, peel extract exhibited significant antiproliferative effect against all tested cancer cell lines, compared to that of flesh extract, in a dose-dependent manner. The result also showed that the antiproliferative activity of mango flesh and peel extracts correlated with their phenolic and flavonoid contents. Thus, mango peel, a major by-product obtained during the processing of mango product, exhibited good antioxidant activity and may serve as a potential source of phenolics with anticancer activity.     

超声波辅助提取菠萝皮渣多糖及其抗氧化活性研究

采用超声波技术辅助提取菠萝皮渣多糖,利用正交设计实验优化其提取工艺,并利用体外实验研究该多糖对羟自由基（·OH）、DPPH自由基（DPPH·）的清除能力及其还原能力,以评价其抗氧化活性。研究结果表明,超声波辅助提取最佳工艺参数为:料液比1∶50（m/v）,时间40 min,温度60℃,功率为570 W,该条件下多糖的得率为2.38%;在本实验浓度范围（1.50³.50 mg/m L）内,菠萝皮渣多糖对·OH的清除率随其浓度的增加而增加,但清除能力均低于同浓度VC,清除DPPH·自由基的IC₅₀为2.47 mg/m L,对Fe³⁺的还原能力随多糖浓度的增加而增加。可见,超声波辅助提取工艺效果较好,能缩短提取时间,提高菠萝皮渣多糖的得率;体外抗氧化实验表明菠萝皮渣多糖具有一定的抗氧化活性。从菠萝皮渣中提取活性多糖,可以变废为宝,实现菠萝资源的高值化利用。      

基于确定性筛选设计优化柑橘皮抗氧化活性成分提取

【目的】柑橘皮抗氧化活性成分的提取工艺参数不明确,本研究采用确定性筛选设计结合设计空间法优化柑橘皮抗氧化活性成分的提取工艺。【方法】首先采用确定性筛选设计考察料液比、碱用量、醇体积分数、提取次数、提取温度和提取时间6个因素对提取效果的影响。然后,代表性抗氧化活性成分橙皮苷、芸香柚皮苷、圣草次苷的峰面积之和作为评价指标,6个因素作为变量因素,通过多元回归算法建立定量模型。基于模拟实验测定误差法计算获得关键因素与评价指标之间的设计空间。【结果】提取过程中,抗氧化活性成分的关键影响因素有3个,分别为提取次数、提取温度和料液比,并成功验证。该3个因素推荐的操作空间是提取次数为1.5~2.9,提取温度为30.2~35.0 ℃,料液比为51:1~60:1。【结论】本研究优选了提取工艺涉及的六个参数对抗氧化活性成分提取的影响,推荐的操作空间可使代表性抗氧化活性成分的峰面积达标概率达到 0. 96 以上,为工业化提取柑橘皮抗氧化活性成分提供了参考。     

柑桔皮色素的提取及其性质研究

研究了五种溶剂对三种柑桔皮中橙黄色素的提取率，选择了提取该色素的最佳条件和工艺流程，并将所得的橙黄色素产品进行了光和热稳定性试验及理化指标检验。     

微波法萃取橘皮中果胶的研究

以橘皮为原料在微波条件下提取果胶进行了研究，探讨盐析pH值、微波加热时间、硫酸铝用量、液料比、盐析温度、盐析时间等因素对果胶产率的影响，结果表明：微波法提取果胶的最佳工艺条件为盐析pH5．0，微波力加热时间5min，硫酸铝用量2．5g，液料比16mL／g，盐析温度60％，盐析时间60min，果胶平均得率25％。     

Thermomechanical process intensification for oil extraction from orange peels

The study investigated the intensification and improvement of oil extraction from orange peel through a thermomechanical process: the instantaneous controlled pressure drop (briefly D.I.C. process). This process involves subjecting orange peel for a short time to steam pressure, followed by an instantaneous decompression to a vacuum at 50 mbar. Central composite design was used to study the combined effects of processing steam pressure (1–7 bar; which corresponds to a temperature ranging between 100 °C and 162 °C respectively), processing time (0.3–3.7 min) and initial moisture content of orange peel before thermomechanical oil extraction (9.8–60.2% on dry material basis). The quantitative analysis, have been undertaken on oil present in orange peels, after processing. Correlation analysis of the mathematical regression model indicated that quadratic polynomial model could be employed to optimize the extraction of oil from orange peel. From response surface plots, the three variables exhibited a linear effect with the strongest effect for the processing pressure. The optimum reaction conditions selected with response surface analysis were as follows: steam processing pressure: 6.6 bar, processing time: 3.68 min, initial moisture content: 53.6% d.m. basis. Under these conditions, experimental yield of orange peel oil was close to predicted value (99%) calculated from the polynomial response surface model equation. A kinetic study indicated that extraction performed by D.I.C. process is clearly quicker than conventional steam distillation method.

Industrial relevance

World production of citrus fruit has experienced continuous growth in the last decades of the XX century. Total annual citrus production was estimated at over 105 million tons in the period 2000–2004 (http://www.unctad.org/infocomm/anglais/orange/market.htm). Oranges constitute the bulk of citrus fruit production, accounting for more than half of global citrus production in 2004. Thus, the quantities of generated by-products are very important. In this study, extraction of oil from orange peel was performed through a thermomechanical process developed in our laboratory. We report on some results obtained using this process as well as others comparing extraction kinetics when using a conventional steam distillation process and the proposed extraction process. One of the advantages of the described method is the short contact of extracted oil with the heated zones in the apparatus resulting in a lower heating period of the product compared to steam distillation. At industrial scale, this is interesting regarding oil quality and energy saving.     

加速溶剂萃取技术提取柑橘皮中总黄酮的工艺研究

应用加速溶剂萃取技术,通过单因素试验和正交试验对柑橘皮中总黄酮提取工艺进行了研究。结果表明,用加速溶剂萃取技术从柑橘皮中提取黄酮的最佳工艺条件为压力10.3MPa、乙醇浓度80%、料液比1∶15、温度70℃、浸提时间10min,此时黄酮得率为2.64%。     

Antioxidant activity of various extracts of old tea leaves and black tea wastes (Camellia sinensis L.)

The antioxidant activity of various extracts of old tea leaves (OTL) and black tea wastes (BTW) in comparison with that of green tea leaves (GTL) was evaluated. The highest extraction yield and antioxidant activity were found in hot water extracts of GTL. Hot water extracts of OTL and BTW showed the same statistically significant antioxidant activities (P < 0.05). Also, there was no statistically significant difference between the antioxidant activities of OTL and BTW extracts obtained by the other two extraction methods (ethyl acetate and methanolic methods) and, in some cases, BTW extracts acted even better than OTL extracts. The antioxidant activity of tea extracts was not concomitant with the development of their reducing power. This suggested that the antioxidant activity of tea extracts likely involves other mechanisms in addition to those of reductones. Totally, BTW extracts had antioxidant activities comparable with or even better than those of OTL extracts. Hence, OTL and BTW, which are often considered as agricultural wastes, can be used as potent natural antioxidative sources.     

Effect of air-drying temperature on physico-chemical properties of dietary fibre and antioxidant capacity of orange (Citrus aurantium v. Canoneta) by-products

Dehydration promoted important modifications affecting both the physico-chemical properties of dietary fibre (DF) and the antioxidant capacity of orange by-products (peel and pulp remaining after juice extraction). The significance of such changes was largely dependent on the air-drying temperature used (from 30 °C to 90 °C). The major modifications on the DF components were observed when either extended drying periods, i.e. at lower temperatures, or elevated drying temperatures were applied. Dehydration around 50–60 °C apparently promoted the minor disruption of cell wall polymers, in particular of pectic substances. Pulp samples exhibited higher values of swelling (SW) and fat adsorption capacity (FAC) than those derived from orange peel. Although, significant decreases in water retention capacity (WRC), FAC and solubility values were detected for both by-products as the air-drying temperature increased. The antioxidant capacity associated to dehydrated citrus by-products was significantly higher for orange peel than for pulp samples. In general, the by-products studied proved to be quite resistant to the different heat treatments applied within the range of 40–70 °C. In overall, the study shows that, in order to preserve either the DF quality and/or the antioxidant capacity, air-drying temperature should be controlled since both types of compounds, DF components and antioxidants, might be degraded or modified either when extended drying periods and/or high drying temperatures are applied.     

Antimicrobial activity of acid-hydrolyzed Citrus unshiu peel extract in milk

Citrus fruit (Citrus unshiu) peels were extracted with hot water and then acid-hydrolyzed using hydrochloric acid. Antimicrobial activities of acid-hydrolyzed Citrus unshiu peel extract were evaluated against pathogenic bacteria, including Bacillus cereus, Staphylococcus aureus, and Listeria monocytogenes. Antilisterial effect was also determined by adding extracts at 1, 2, and 4% to whole, low-fat, and skim milk. The cell numbers of B. cereus, Staph. aureus, and L. monocytogenes cultures treated with acid-hydrolyzed extract for 12 h at 35°C were reduced from about 8 log cfu/mL to <1 log cfu/mL. Bacillus cereus was more sensitive to acid-hydrolyzed Citrus unshiu peel extract than were the other bacteria. The addition of 4% acid-hydrolyzed Citrus unshiu extracts to all types of milk inhibited the growth of L. monocytogenes within 1 d of storage at 4°C. The results indicated that Citrus unshiu peel extracts, after acid hydrolysis, effectively inhibited the growth of pathogenic bacteria. These findings indicate that acid hydrolysis of Citrus unshiu peel facilitates its use as a natural antimicrobial agent for food products.     

澳洲坚果青皮多酚提取工艺优化及其抗氧化活性

以新鲜澳洲坚果青皮为原料,研究了澳洲坚果青皮多酚的提取工艺及抗氧化活性。在单因素实验的基础上,通过4因素3水平的正交实验优化澳洲坚果青皮多酚提取工艺,并以Trolox为对照,研究其对DPPH自由基和ABTS+自由基的清除能力以及总抗氧化能力。正交实验结果表明:提取时间为90 min、料液比为1∶50（g/m L）、提取温度为50℃、乙醇体积分数为40%为最佳提取工艺条件,在此条件下澳洲坚果青皮多酚提取量达到（1027.47±10.76）mg/100 g。抗氧化实验结果表明:澳洲坚果青皮多酚对DPPH自由基和ABTS+自由基的半数清除率IC50分别为4.13、112.94 mg/L,且其总抗氧化能力约为Trolox的1.7倍。由此可知,澳洲坚果青皮多酚具有很强的抗氧化能力,可用于制备天然抗氧化剂。