• <tr id="yyy80"></tr>
  • <sup id="yyy80"></sup>
  • <tfoot id="yyy80"><noscript id="yyy80"></noscript></tfoot>
  • 99热精品在线国产_美女午夜性视频免费_国产精品国产高清国产av_av欧美777_自拍偷自拍亚洲精品老妇_亚洲熟女精品中文字幕_www日本黄色视频网_国产精品野战在线观看 ?

    Optimization of Synthesis Process for Oleoyl-alginate Ester by Response Surface Methodology

    2011-03-31 03:28:18LIQianLIUChenguang
    食品科學(xué) 2011年10期
    關(guān)鍵詞:響應(yīng)面法

    LI Qian,LIU Chen-guang

    (College of Marine Life Sciences, Ocean University of China, Qingdao 266003, China)

    李 倩,劉晨光*

    (中國海洋大學(xué)海洋生命學(xué)院,山東 青島 266003)

    Optimization of Synthesis Process for Oleoyl-alginate Ester by Response Surface Methodology

    LI Qian,LIU Chen-guang*

    (College of Marine Life Sciences, Ocean University of China, Qingdao 266003, China)

    Abstract:Box-Behnken experimental design and response surface methodology (RSM) were combinedly employed to evaluate the effects of the amounts of formic acid and oleoyl chloride as well as reaction temperature and time on the synthesis of oleoylalginate ester (OAE). The optimum synthesis conditions of OAE were found to be alginate amount of 0.5 g, formic acid amount of 4.95 mL, oleoyl chloride amount of 11.27 mL, reaction temperature of 50 ℃ and reaction time of 20 min. Under these conditions, the maximum degree of substitution (DS) and yield of OAE were observed to be respectively 4.93% and 92.27%, which were in accordance with the corresponding predicted values.

    Key words:oleoyl-alginate ester (OAE);response surface methodology (RSM);synthesis process

    李 倩,劉晨光*

    (中國海洋大學(xué)海洋生命學(xué)院,山東 青島 266003)

    Alginate, a natural linear polysaccharide, is widely used in food industry owing to its good properties such as biocompatibility, bioadhesiveness, and non-toxicity, et al[1]. Amphiphilic derivatives of alginate formed strong hydrogels that serve as a carrier for drugs and nutraceuticals[2-4]. In order to increase the hydrophobic properity, alginate has been modified by various hydrophobic groups such as noctylamine groups, alkyl chains (C12and C18), and cholesteryl by different procedures. However, these amphiphilic derivatives of alginate were synthesized in the presence of organic solvent, such as chloroform, dichloromethane, and dimethyl sulfoxide[4]. The organic solvents may irritate and damage the skin, eyes and respiratory passages[5]. Moreover, organic solvents cause fetal harm because it can readily cross the placenta and reach the fetal nervous system[6].

    In our previous study acid (oleoyl chloride) has been successfully grafted to alginate without any organic solvents. The nanoparticles formed by oleoyl-alginate ester (OAE) has good size, morphic and thermodynamic stability and can be used as carriers for liposoluble nutraceuticals with controlled release in gastrointestinal fluid[4]. However, the OAE were synthesized with no attempt to optimize the synthesis protocols. The classical method of studying one variable at a time may be effective in some situations, but fails to consider the combined effects of all the factors involved[7]. Response surface methodology (RSM), a collection of statisti-cal and mathematical methods, is useful for developing, improving, and optimizing the processes[8]. The advantage of RSM is that it can reduce the number of experimental trials, evaluate the interactions between multiple parameters. Moreover, it is more effective and precise than many approaches[9]. RSM has already been successfully applied optimizing chemical reactions[10]. RSM could successfully optimize the chemical reaction conditions of various synthesis processes.

    The objective of this study was to optimize the synthesis of OAE by RSM. The reaction variables investigated included the amount of formic acid, the amount of oleoyl chloride, reaction temperature and reaction time.

    1 Materials and Methods

    1.1Materials, reagents and instruments

    Sodium alginate, formic acid, oleoyl chloride, and ethanol were purchased from Sigma chemicals (St. Louis, MO, USA). Low molecular weight alginate was obtained by the method of acid hydrolyze and its relative molecular mass was 1.72×104.

    Design-Expert version 7.1 software (Stat-Ease Inc., USA), homothermal magnetic stirrer (Guosheng Co., China), and nuclear magnetic resonance (NMR) spectrometer (JEOL Co., Japan) were used in this study.

    1.2Methods

    1.2.1Preparation of oleoyl alginate ester (OAE)

    OA was prepared by reacting low molecular alginate with oleoyl chloride derived from a previous work[4]. The reaction was carried out in a three-necked flask, which was placed in homothermal magnetic stirrer. The formylation reaction was carried out by impregnating 0.5 g alginate with formic acid (5-20 mL) for 10 min at 25 ℃ under stirring. Oleoyl chloride (8-45 mL) was then added dropwise. The reaction mixture was then heated, and the temperature (30-70 ℃) was maintained for times ranging from 10 to 40 min. At the end of the reaction, 100 mL of 95% ethanolwas added to terminate the reaction, and the mixture was filtered to obtain solid phase. The solid phase was washed with 95% ethanol several times and dried under vacuum at room temperature.

    1.2.2Determination of the degree of substitution (DS)

    The degree of substitution (DS), which represents the amount of oleoyl chains per 100 hexurunic acid residues, was calculated by comparing the ratio of methylene protons correlated with carbon 8 and 11 of oleoyl graft (δ = 2.0) to carbon 3-5 of alginate protons (δ = 3.3-3.7) in1H NMR spectra using equation 1[11]:

    AOand AAcorrespond to the area of the methylene protons on oleoyl grafts and the carbon 3-5 of alginate protons on alginate main chains.

    1.2.3Calculation of the percent yield

    The percent yield of OAE was calculated as follows[12]:

    Percent yield of OA/%= the solid obtained/initial alginate ×100

    1.2.4Single factor analysis

    Single-factor-test was employed to determine the preliminary range of the reaction variables including the amount of formic acid, the amount of oleoyl chloride, reaction temperature and reaction time.

    1.2.5The Response Surface Method

    A three-level four-factor RSM along with Box-Behnken design was used in this study to optim ize the reaction conditions. The DS and reaction y ields were treated as responses. Design-Expert version 7.1 software was used to generate the experimental designs, statistical analysis and regression model.

    2 Results and Discussions

    2.1Single factor analysis

    The effects of the amount of formic acid or oleoyl chloride to alginate, reaction temperature and reaction time on the DS and yield of OAE are demonstrated in figure 1a, 1b, 1c and 1d, respectively. Besides the calculation of DS, the new peaks and increased peaks in1H NMR spectra also confirmed the presence of oleoyl graft linked to alginate in the former article[4]. The former includedδ2.3= CH2(carbon 2 of oleoyl graft), δ2.0= CH2(carbon 8 and 11 of oleoyl graft) and δ1.7= CH2(carbon 3 of oleoyl graft), and the latter includedδ1.2= CH2(carbon 4-7 and 12-17 of oleoyl graft) and δ0.8= CH3(carbon 18 of oleoyl graft).

    Fig.1 Effect of the variables on the DS and yield of OAE

    2.1.1Effect of the amount of formic acid

    As shown in Fig.1a, the effect of the amount of formic acid (2.5 to 10 mL) was investigated, while other variables were set as follows: 8 mL oleoyl chloride, reaction temperature 50 ℃, and reaction time 20 min. The DS of OAE increased with the amount of formic acid until 5 mL and began to decrease sharply. The maximum yield was (31.89 ± 91)% at 3.5 and decreased rapidly beyond 5 mL. So, we adopted 2.5-5 mL formic acid.

    2.1.2Effect of the amount of oleoyl chloride

    The amount of oleoyl chloride had small effect of the DS and yield of OAE, while other variables were set as follows: 5 mL formic acid, reaction temperature 50 ℃, and reaction time 20 min (Fig.1b). In consideration of the price of oleoyl chloride, the minimum and maximum amount was chosen as 8 mL and 20 mL, respectively.

    2.1.3Effect of the reaction temperature

    The effect of the temperature was shown in Fig.1c, when other experimental conditions were as follows: 5 mL formic acid, 8 mL oleoyl chloride, and reaction time 20 min. As the amount of reaction temperature increased, there was an increase in the DS of OAE. But the yield of OAE decreased, especially beyond the temperature of 50 ℃. Therefore, 30 ℃and 50 ℃ were chosen as the reaction time range.

    2.1.4Effect of the reaction time

    Fig.1d shows the effect of the time on the DS and yield of OAE while other experimental conditions were as follows: 5 mL formic acid, 8 mL oleoyl chloride, and reaction temperature 50 ℃. The yield of OAE decreased slowly from 86.3% to 78.34% as the reaction temperature increased. But the DS of OAE was extremely low at reaction time of 10 min, and the maximum DS of 4.99 was observed at reaction time of 40 min. Therefore, we adopted reaction time 20-40 min.

    2.2Predicted model and statistical analysis

    Table1 Box-Behnken design matrix and the responses of the DS and yield

    Table2 Analysis of variance (ANOVA) for the quadratic model of DS

    Table3 Analysis of variance (ANOVA) for the quadratic model of yield

    The design matrix and the corresponding results of RSM experiments to determine the effects of the four independent variables including amount of formic acid (A), amount of oleoyl chloride (B), reaction time (C) and reaction temperature (D) were shown in Table 1. The application of RSM yielded the following second-order polynomial function:

    DS=9.76856-2.14400A+0.77435B-0.18850C-0.22483D-0.093667AB+0.015000AC+0.053600AD-0.001875BC-0.005625BD+0.00370CD+0.12373A2-0.00327546B2-0.00121667C2+0.000145833D2

    Yield=-89.98787+26.45800A+3.80148B+4.55758C+2.68450D+0.63033AB-0.4044AC+0.13820AD -0.064458BC+0.0005BD-0.071625CD-4.34293A2-0.21440B2+0.00441667C2-0.010708D2

    The analysis of variance (ANOVA) for the quadratic model of DS and yield are shown in Table 2 and 3, respectively. The significance of each coefficient was determined by F-test and P-values. The larger the magnitude of the F-value and smaller the P-value, the more significant is the corresponding coefficient[13-14]. The F-value with a very low P-value of DS and yield demonstrate a high significance for the regression models. For the DS, B, C, D, AB, AD, BD, CD and A2are significant model terms. For the yield, A, B, C, D, AC, BC, CD, A2, B2are significant model terms.

    2.3Process analysis

    Fig.2 Response surface plots showing the effect of combined variables on the DS

    Fig.3 Response surface plots showing the effect of combined variables on the yield

    The response surface plot of significant model terms[15]for DS is shown in Fig.2(a, b, c and d), when other variables are fixed at 0 level. In Fig.2a, at the lowest the amount of formic acid, an increase in the amount of oleoyl chloride enhances the DS of OAE. At highest the amount of oleoyl chloride, a decrease in the amount of oleoyl chloride led to an increase in the DS. The highest DS is obtained at the highest the amount of formic acid and the highest reaction temperature in Fig.2b. The DS increases with the amount of oleoyl chloride reaction time and reaction temperature in Fig. 2c and 2d.

    The response surface plots of significant model terms for yield are shown in Fig.3(a, b and c), which indicates maximal yield is obtained at about middle the amount of formic acid, low the amount of oleoyl chloride, long reaction time and high reaction temperature. Compared to other independent variables, time has less effect on the yield.

    2.4Process optimization

    When DS weights 4 and yield weights 2, maximum DS and yield were 5% and 93.99%, respectively, for the following condition: 4.95 mL formic acid, 11.27 mL oleoyl chloride, reaction time 20 min and reaction temperature 50 ℃. In the optimal conditions, the experimental values of DS and yield were 4.93% and 92.27%, respectively, which agreed with the predicted value. Therefore, the results indicated suitability of the model employed and the success of RSM in optimizing the extraction conditions[16].

    3 Conclusion

    Optimization of the synthesis of OAE using RSM along with Box-Behnken design was performed. The regression models of DS and yield had high significance. For the DS, B, C, D, AB, AD, BD, CD and A2are significant model terms. For the yield, A, B, C, D, AC, BC, CD, A2, B2are significant model terms. The optimal conditions were 4.95 mL formic acid, 11.27 mL oleoyl chloride, reaction temperature 50 ℃ and reaction time 20 min, when the amount of alginate was 0.5 g. Maximum DS and yield were 4.93% and 92.27%, respectively, which agreed with the predicted value.

    References:

    [1]LERTSUTTHIWONG P, NOOMUN K, JONGAROONNGAMSANG N, et al. Preparation of alginate nanocapsules containing turmeric oil[J]. Carbohydr Polym, 2008, 74(2): 209-214.

    [2]YANG Liqun, ZHANG Bifang, WEN Liqun, et al. Amphiphilic cholesteryl grafted sodium alginate derivative: Synthesis and self-assembly in aqueous solution[J]. Carbohydr Polym, 2007, 68(2): 218-225.

    [3]YAO Bolong, NI Caihua, XIONG Cheng. Hydrophobic modification of sodium alginate and its application in drug controlled release[J]. Bioprocess Biosyst Eng, 2010, 33(4): 457-463.

    [4]LI Qian, LIU Chenguang, XUE Fangfang, et al. Preparation and charac-terization of nanoparticles based on oleoyl-alginate as oral vehicles for vitamin D3[J]. J Agric Food Chem, 2011, 59(5): 1962-1967.

    [5]SHAW S, SHAW D S, ROSSOL M. Overexposure: health hazards in photography[M]. New York: Allworth Press, 1991.

    [6]LADOU J. Current occupational & environmental medicine[M]. New York: The McGraw-Hill Companies, 2003.

    [7]ELIBOL M, OZER D. Response surface analysis of lipase production by freely suspended Rhizopus arrhizus[J]. Process Biochem, 2002, 38(3): 367-372.

    [8]LIN J F, CHOU C C. The response surface method and the analysis of mild oxidational wear[J]. Tribol Int, 2002, 35(11): 771-785.

    [9]GUO Xia, ZOU Xiang, SUN Min. Optimization of extraction process by response surface methodology and preliminary characterization of polysaccharides from Phellinus igniarius[J]. Carbohydr Polym, 2010, 80(2): 344-349.

    [10]KHOO L P, CHEN C H. Integration of response surface methodology with genetic algorithms[J]. Cirp Ann-Manuf Techn, 2001, 18(7): 483-489.

    [11]ELOMAA M, ASPLUND T, SOININEN P, et al. Determination of the degree of substitution of acetylated starch by hydrolysis,1H NMR and TGA/IR[J]. Carbohydr Polym, 2004, 57(3): 261-267.

    [12]YUE Wu, YAO Pingjia, WEI Yuanan, et al. An innovative method for preparation of acid-free-water-soluble low-molecular-weight chitosan (AFWSLMWC)[J]. Food Chem, 2008, 108(3): 1082-1087.

    [13]ADINARAYANA K, ELLAIAH P, SRINIVASULU B, et al. Response surface methodological approach to optimize the nutritional parameters for neomycin production by Streptomyces marinensis under solid-state fermentation[J]. Process Biochem, 2003, 38(11): 1565-1572.

    [14]WU Shijin, YU Xiang, HU Zhihang, et al. Optimizing aerobic biodegradation of dichloromethane using response surface methodology[J]. J Environ Sci, 2009, 21(9): 1276-1283.

    [15]YE Ling. WU Yinglong. Optimization of bleached pulverized konjac flour preparation process by response surface method[J]. Food Science, 2008, 29(6): 151-155.

    [16]CHO I H, ZOH K D. Photocatalytic degradation of azo dye (Reactive Red 120) in TiO2/UV system: Optimization and modeling using a response surface methodology (RSM) based on the central composite design[J]. Dyes Pigments, 2007, 75(3): 533-543.

    E-mail:liucg@ouc.edu.cn

    中圖分類號:TS236.9

    文獻標(biāo)識碼:A

    文章編號:1002-6630(2011)10-0006-06

    收稿日期:2010-06-30

    基金項目:國家“863”計劃項目(2007AA10Z349)

    作者簡介:李倩(1984—),女,博士研究生,研究方向為納米技術(shù)在食品中的應(yīng)用。E-mail:kikyoqq@163.com

    *通信作者:劉晨光(1968—),男,教授,博士,研究方向為納米技術(shù)在生物、醫(yī)藥與食品中的應(yīng)用。

    響應(yīng)面法優(yōu)化油酰海藻酸酯的合成工藝

    摘 要:采用響應(yīng)面法分析不同因素對油酰海藻酸酯合成工藝的影響。選擇甲酸用量、油酰氯用量、反應(yīng)溫度和反應(yīng)時間4個因素,采用響應(yīng)面分析法,根據(jù)Box-Behnken組合設(shè)計原理設(shè)計試驗。結(jié)果表明:最適條件為海藻酸量0.5g、4.95mL甲酸、11.27mL油酰氯、反應(yīng)溫度50℃、反應(yīng)時間20min。在此條件下,取代度可達4.93%、產(chǎn)率可達92.27%,與方程的預(yù)測值相符。

    關(guān)鍵詞:油酰海藻酸酯;響應(yīng)面法;合成工藝

    猜你喜歡
    響應(yīng)面法
    響應(yīng)面法優(yōu)化超聲波輔助提取白頭翁總皂苷
    菌糠中產(chǎn)纖維素酶菌株的篩選、鑒定及增殖條件響應(yīng)面法優(yōu)化
    玉米皮類黃酮超聲波提取工藝優(yōu)化及其抗氧化活性研究
    基于響應(yīng)面法的聽小骨消聲器的優(yōu)化設(shè)計
    山藥多糖提取工藝優(yōu)化及其抗菌活性研究
    微波輔助提取白頭翁皂苷研究
    響應(yīng)面法優(yōu)化超聲輔助提取蕎麥中蘆丁的工藝
    菊芋膳食纖維酸奶的工藝研究及營養(yǎng)分析
    船舶舷側(cè)構(gòu)件幾何尺寸優(yōu)化分析
    科技視界(2016年21期)2016-10-17 17:22:54
    可溶性大豆多糖超聲波提取工藝及其抗氧化性研究
    免费大片18禁| 精品国产乱码久久久久久小说| 九草在线视频观看| 亚洲成人一二三区av| 男插女下体视频免费在线播放| 色吧在线观看| 亚洲成人av在线免费| av线在线观看网站| 好男人视频免费观看在线| 搡女人真爽免费视频火全软件| 天堂中文最新版在线下载 | 在线观看一区二区三区激情| 禁无遮挡网站| 国产成人精品福利久久| 成年人午夜在线观看视频| 国产av国产精品国产| 成人国产av品久久久| 欧美高清性xxxxhd video| 亚洲av.av天堂| 亚洲国产高清在线一区二区三| 国产色爽女视频免费观看| 嫩草影院入口| 国产成人免费观看mmmm| 国内精品美女久久久久久| 久久久久久久大尺度免费视频| 日日摸夜夜添夜夜爱| 国产精品秋霞免费鲁丝片| 你懂的网址亚洲精品在线观看| 欧美一级a爱片免费观看看| 国产黄a三级三级三级人| 欧美精品一区二区大全| 日韩欧美一区视频在线观看 | 高清视频免费观看一区二区| 一级av片app| videossex国产| 夫妻午夜视频| 99久久中文字幕三级久久日本| 久久精品久久久久久噜噜老黄| av天堂中文字幕网| 久久久精品免费免费高清| 婷婷色av中文字幕| 99久久精品国产国产毛片| 精品久久国产蜜桃| 精品久久久久久久久亚洲| 日韩电影二区| 国产精品精品国产色婷婷| 国产av码专区亚洲av| 99久国产av精品国产电影| 亚洲欧美日韩无卡精品| 三级国产精品片| 欧美bdsm另类| 啦啦啦啦在线视频资源| 国产亚洲5aaaaa淫片| av在线app专区| 亚洲欧美清纯卡通| 国产精品秋霞免费鲁丝片| 欧美一级a爱片免费观看看| 舔av片在线| 亚洲三级黄色毛片| 国产男人的电影天堂91| 久久久a久久爽久久v久久| 亚洲精品日韩av片在线观看| 国产精品伦人一区二区| 久久精品人妻少妇| 婷婷色av中文字幕| 美女xxoo啪啪120秒动态图| 国产极品天堂在线| 国产欧美亚洲国产| 国产在视频线精品| 边亲边吃奶的免费视频| 免费黄色在线免费观看| 少妇人妻 视频| 男女那种视频在线观看| 寂寞人妻少妇视频99o| 最近2019中文字幕mv第一页| 26uuu在线亚洲综合色| 国产精品人妻久久久久久| 禁无遮挡网站| 国产极品天堂在线| 亚洲av不卡在线观看| 我的老师免费观看完整版| 亚洲欧美一区二区三区国产| 亚洲国产欧美在线一区| 高清在线视频一区二区三区| 七月丁香在线播放| 熟女av电影| 成年人午夜在线观看视频| 少妇人妻 视频| kizo精华| 国产美女午夜福利| 久久人人爽人人爽人人片va| 国产av码专区亚洲av| 亚洲av在线观看美女高潮| 国产精品av视频在线免费观看| 国产爽快片一区二区三区| 日产精品乱码卡一卡2卡三| 精品99又大又爽又粗少妇毛片| 日日撸夜夜添| 91精品一卡2卡3卡4卡| 国产人妻一区二区三区在| 亚洲综合色惰| 国产午夜福利久久久久久| 国产久久久一区二区三区| 成人特级av手机在线观看| 日韩欧美一区视频在线观看 | 在线 av 中文字幕| 国产真实伦视频高清在线观看| 人妻系列 视频| 亚洲国产高清在线一区二区三| 久久精品熟女亚洲av麻豆精品| 亚洲人与动物交配视频| 91在线精品国自产拍蜜月| 国产精品久久久久久精品电影| 十八禁网站网址无遮挡 | 真实男女啪啪啪动态图| 国产国拍精品亚洲av在线观看| 国产毛片a区久久久久| 男人和女人高潮做爰伦理| 精品一区二区免费观看| 看免费成人av毛片| av黄色大香蕉| 亚洲aⅴ乱码一区二区在线播放| 国产成人91sexporn| 日本黄大片高清| 九九爱精品视频在线观看| 搡老乐熟女国产| 亚洲精品aⅴ在线观看| 亚洲av成人精品一区久久| 国精品久久久久久国模美| 欧美日韩在线观看h| 国产午夜精品一二区理论片| 超碰97精品在线观看| 国产精品嫩草影院av在线观看| 久久久精品94久久精品| 黄片无遮挡物在线观看| 免费人成在线观看视频色| 综合色av麻豆| av天堂中文字幕网| 男插女下体视频免费在线播放| 草草在线视频免费看| 乱码一卡2卡4卡精品| 中国国产av一级| 久久精品人妻少妇| 国产成人精品福利久久| 真实男女啪啪啪动态图| 精品人妻熟女av久视频| 精品午夜福利在线看| 亚洲真实伦在线观看| 日韩在线高清观看一区二区三区| 超碰97精品在线观看| 搡老乐熟女国产| 亚洲欧美精品自产自拍| 久久精品国产亚洲av天美| 国产精品爽爽va在线观看网站| 欧美亚洲 丝袜 人妻 在线| 麻豆久久精品国产亚洲av| a级一级毛片免费在线观看| 观看免费一级毛片| 美女cb高潮喷水在线观看| 在线观看国产h片| 我的女老师完整版在线观看| 国产极品天堂在线| 免费黄频网站在线观看国产| 91在线精品国自产拍蜜月| 日韩中字成人| 大香蕉久久网| 麻豆乱淫一区二区| 超碰av人人做人人爽久久| 哪个播放器可以免费观看大片| 国产高潮美女av| 在线天堂最新版资源| 内射极品少妇av片p| 亚洲人成网站在线观看播放| 内地一区二区视频在线| 久久精品国产亚洲网站| 青青草视频在线视频观看| eeuss影院久久| 亚洲国产精品999| 最近2019中文字幕mv第一页| 成人特级av手机在线观看| 自拍偷自拍亚洲精品老妇| 岛国毛片在线播放| 亚洲精品国产av蜜桃| 午夜老司机福利剧场| 亚洲欧美日韩卡通动漫| 国产高清国产精品国产三级 | 精品酒店卫生间| 成人午夜精彩视频在线观看| 蜜桃亚洲精品一区二区三区| 少妇裸体淫交视频免费看高清| 日本wwww免费看| 国产精品一区二区性色av| 波多野结衣巨乳人妻| 热re99久久精品国产66热6| 欧美成人a在线观看| 亚洲欧洲日产国产| 亚洲精品视频女| 大香蕉久久网| 国产精品一区二区三区四区免费观看| 麻豆成人av视频| 精品久久久噜噜| 中文字幕人妻熟人妻熟丝袜美| 干丝袜人妻中文字幕| 一区二区三区免费毛片| 欧美精品国产亚洲| 日韩欧美 国产精品| 联通29元200g的流量卡| 青春草国产在线视频| 观看美女的网站| 一级毛片 在线播放| 免费av不卡在线播放| 伦精品一区二区三区| 成年女人在线观看亚洲视频 | 麻豆成人av视频| 80岁老熟妇乱子伦牲交| 欧美一级a爱片免费观看看| 亚洲av不卡在线观看| 春色校园在线视频观看| 国产精品三级大全| 我的老师免费观看完整版| 久久亚洲国产成人精品v| 伊人久久国产一区二区| 最近手机中文字幕大全| av免费在线看不卡| 亚洲av日韩在线播放| 免费大片黄手机在线观看| a级一级毛片免费在线观看| 国产精品.久久久| 夜夜看夜夜爽夜夜摸| 日韩人妻高清精品专区| 国产 一区精品| 97人妻精品一区二区三区麻豆| 亚洲天堂av无毛| 日韩精品有码人妻一区| av国产免费在线观看| 亚洲天堂av无毛| www.色视频.com| 精品一区在线观看国产| 久久99热这里只频精品6学生| 亚洲精品久久午夜乱码| 亚洲,一卡二卡三卡| 色视频在线一区二区三区| 午夜福利视频精品| 国产精品99久久99久久久不卡 | 日韩欧美精品免费久久| 春色校园在线视频观看| 成年人午夜在线观看视频| 亚洲av免费高清在线观看| 好男人在线观看高清免费视频| 最近2019中文字幕mv第一页| 热re99久久精品国产66热6| 人妻系列 视频| 熟妇人妻不卡中文字幕| 欧美变态另类bdsm刘玥| 亚洲av日韩在线播放| 日韩精品有码人妻一区| 成人漫画全彩无遮挡| 美女cb高潮喷水在线观看| 久久精品国产鲁丝片午夜精品| 国产精品国产av在线观看| 天堂中文最新版在线下载 | 噜噜噜噜噜久久久久久91| 毛片女人毛片| 中文字幕亚洲精品专区| 丝袜喷水一区| 国产毛片在线视频| 中文天堂在线官网| 一级毛片 在线播放| 青青草视频在线视频观看| 国产亚洲精品久久久com| 国产精品久久久久久久久免| 国产亚洲av片在线观看秒播厂| 在线播放无遮挡| 寂寞人妻少妇视频99o| 久久精品国产自在天天线| 色哟哟·www| 少妇猛男粗大的猛烈进出视频 | 伊人久久精品亚洲午夜| 在线看a的网站| 少妇丰满av| 亚洲精品国产成人久久av| 亚洲aⅴ乱码一区二区在线播放| 欧美激情在线99| 午夜福利视频精品| 在线免费观看不下载黄p国产| 新久久久久国产一级毛片| 免费av观看视频| 三级国产精品欧美在线观看| 在线观看一区二区三区| 搡老乐熟女国产| 婷婷色综合www| 秋霞在线观看毛片| 在线观看一区二区三区激情| 亚洲欧美日韩东京热| 亚洲av欧美aⅴ国产| 搡女人真爽免费视频火全软件| 久久ye,这里只有精品| 国产精品熟女久久久久浪| 中文字幕久久专区| 亚洲欧美成人精品一区二区| 欧美三级亚洲精品| 九九久久精品国产亚洲av麻豆| 一级毛片久久久久久久久女| 黄色视频在线播放观看不卡| 精品视频人人做人人爽| 久久久久久九九精品二区国产| 国产成人精品婷婷| 久久久久网色| 最近最新中文字幕大全电影3| 国产白丝娇喘喷水9色精品| 亚洲精品自拍成人| 亚洲av免费在线观看| 91精品伊人久久大香线蕉| 热re99久久精品国产66热6| 成人午夜精彩视频在线观看| 国产高潮美女av| 久久久久久久久大av| 日本爱情动作片www.在线观看| 99热6这里只有精品| 欧美一级a爱片免费观看看| 免费观看av网站的网址| 中文精品一卡2卡3卡4更新| 久久久久九九精品影院| 美女视频免费永久观看网站| 小蜜桃在线观看免费完整版高清| 午夜福利在线观看免费完整高清在| 亚洲欧洲国产日韩| 国产成人福利小说| 王馨瑶露胸无遮挡在线观看| 免费看av在线观看网站| 免费av观看视频| 久久久亚洲精品成人影院| 2018国产大陆天天弄谢| 王馨瑶露胸无遮挡在线观看| 免费看日本二区| 精品一区二区三卡| 色综合色国产| 日本色播在线视频| 舔av片在线| 男人爽女人下面视频在线观看| 男女无遮挡免费网站观看| 国产免费福利视频在线观看| 男人舔奶头视频| 国产视频首页在线观看| 亚洲欧美中文字幕日韩二区| 欧美日本视频| 22中文网久久字幕| 在线观看国产h片| 极品教师在线视频| 精品酒店卫生间| 一区二区三区精品91| 嫩草影院精品99| 免费黄色在线免费观看| a级一级毛片免费在线观看| 国产高潮美女av| 七月丁香在线播放| 日本av手机在线免费观看| 亚洲不卡免费看| 日韩,欧美,国产一区二区三区| 精品人妻视频免费看| 成人亚洲精品av一区二区| 可以在线观看毛片的网站| 熟女电影av网| 亚洲av成人精品一二三区| 亚洲最大成人av| 亚洲va在线va天堂va国产| 国产精品蜜桃在线观看| 日韩欧美一区视频在线观看 | 午夜日本视频在线| 99久久中文字幕三级久久日本| 最后的刺客免费高清国语| 国产色爽女视频免费观看| 三级男女做爰猛烈吃奶摸视频| 国产一区二区在线观看日韩| 黄色怎么调成土黄色| 国产乱来视频区| 亚洲精华国产精华液的使用体验| 免费观看a级毛片全部| 亚洲av电影在线观看一区二区三区 | 黄色视频在线播放观看不卡| 成人美女网站在线观看视频| 22中文网久久字幕| 成人漫画全彩无遮挡| 成人亚洲精品av一区二区| av福利片在线观看| 亚洲国产欧美在线一区| 精品人妻熟女av久视频| 亚洲人成网站在线观看播放| 亚洲熟女精品中文字幕| 久久97久久精品| av线在线观看网站| 欧美日韩一区二区视频在线观看视频在线 | 大话2 男鬼变身卡| 97在线视频观看| 男人狂女人下面高潮的视频| 亚洲av二区三区四区| 又粗又硬又长又爽又黄的视频| 久久久久精品性色| 天天一区二区日本电影三级| 日韩制服骚丝袜av| 色婷婷久久久亚洲欧美| 国产欧美日韩精品一区二区| 亚洲av日韩在线播放| 精品久久久久久久久av| 国产亚洲av嫩草精品影院| 欧美潮喷喷水| 中文天堂在线官网| 国产亚洲91精品色在线| 丝袜脚勾引网站| a级一级毛片免费在线观看| 久久热精品热| 一级二级三级毛片免费看| 99热6这里只有精品| 国产伦理片在线播放av一区| 2021天堂中文幕一二区在线观| 在线观看国产h片| 又爽又黄无遮挡网站| 波野结衣二区三区在线| 爱豆传媒免费全集在线观看| 人妻少妇偷人精品九色| 麻豆成人av视频| 黑人高潮一二区| 欧美丝袜亚洲另类| 伦理电影大哥的女人| 各种免费的搞黄视频| 一级黄片播放器| 亚洲色图av天堂| 国产成人福利小说| 内地一区二区视频在线| 22中文网久久字幕| 女人十人毛片免费观看3o分钟| av线在线观看网站| 交换朋友夫妻互换小说| 少妇裸体淫交视频免费看高清| 涩涩av久久男人的天堂| 日韩av不卡免费在线播放| 欧美日韩视频高清一区二区三区二| 免费黄网站久久成人精品| 寂寞人妻少妇视频99o| 亚洲av电影在线观看一区二区三区 | 国产爽快片一区二区三区| 成人毛片60女人毛片免费| 校园人妻丝袜中文字幕| 中文在线观看免费www的网站| 久久精品人妻少妇| 午夜免费鲁丝| 高清在线视频一区二区三区| 男的添女的下面高潮视频| 久久午夜福利片| 香蕉精品网在线| 看十八女毛片水多多多| 一级片'在线观看视频| 欧美亚洲 丝袜 人妻 在线| 黄片无遮挡物在线观看| 大香蕉97超碰在线| 国产精品99久久久久久久久| 最近最新中文字幕免费大全7| 中文字幕亚洲精品专区| 交换朋友夫妻互换小说| 一区二区三区免费毛片| 亚洲精品一二三| 国产精品av视频在线免费观看| 97精品久久久久久久久久精品| 白带黄色成豆腐渣| 丰满乱子伦码专区| 蜜桃久久精品国产亚洲av| 1000部很黄的大片| 91精品伊人久久大香线蕉| 国产欧美日韩精品一区二区| 五月伊人婷婷丁香| 99久国产av精品国产电影| 欧美+日韩+精品| xxx大片免费视频| 香蕉精品网在线| 亚洲精品aⅴ在线观看| 亚洲色图综合在线观看| 亚洲三级黄色毛片| 免费观看a级毛片全部| 亚洲精品日本国产第一区| 99久久九九国产精品国产免费| 国产高清国产精品国产三级 | 免费看av在线观看网站| 在线a可以看的网站| 国产高清国产精品国产三级 | 最近最新中文字幕免费大全7| 人妻少妇偷人精品九色| 看免费成人av毛片| 国产精品三级大全| 免费黄网站久久成人精品| 天天躁夜夜躁狠狠久久av| 毛片一级片免费看久久久久| 午夜免费观看性视频| 亚洲av.av天堂| 干丝袜人妻中文字幕| 日本黄大片高清| 91久久精品国产一区二区成人| a级一级毛片免费在线观看| 国产精品秋霞免费鲁丝片| 青春草国产在线视频| 免费观看在线日韩| 国产精品女同一区二区软件| 在线观看人妻少妇| 黄片无遮挡物在线观看| 日本欧美国产在线视频| 久久久久国产网址| 男女边吃奶边做爰视频| videos熟女内射| 亚洲精品日韩av片在线观看| 丝袜脚勾引网站| 精品国产一区二区三区久久久樱花 | av在线app专区| 国产精品偷伦视频观看了| 麻豆成人午夜福利视频| 亚洲欧美精品自产自拍| 女人十人毛片免费观看3o分钟| 国产毛片在线视频| xxx大片免费视频| 国产精品久久久久久久久免| 国产爱豆传媒在线观看| 午夜福利视频1000在线观看| 色综合色国产| 在线观看免费高清a一片| 亚洲国产精品999| 国产成人福利小说| 免费黄频网站在线观看国产| 国产一区二区在线观看日韩| 免费黄色在线免费观看| 永久网站在线| 亚洲va在线va天堂va国产| 大香蕉久久网| 久久久精品欧美日韩精品| 人人妻人人看人人澡| 成人特级av手机在线观看| 成人一区二区视频在线观看| 国产精品人妻久久久影院| tube8黄色片| 亚洲怡红院男人天堂| 91精品国产九色| 国产精品偷伦视频观看了| 亚洲欧美中文字幕日韩二区| 欧美三级亚洲精品| 18禁裸乳无遮挡免费网站照片| 人妻制服诱惑在线中文字幕| 成人特级av手机在线观看| 成年女人在线观看亚洲视频 | 51国产日韩欧美| 三级国产精品欧美在线观看| 久久久久九九精品影院| 网址你懂的国产日韩在线| 偷拍熟女少妇极品色| 欧美变态另类bdsm刘玥| 久久久久久国产a免费观看| 免费少妇av软件| 国产精品国产三级国产av玫瑰| av线在线观看网站| 亚洲av男天堂| 免费黄频网站在线观看国产| 精品一区二区免费观看| 久久精品国产a三级三级三级| 国产 一区精品| 免费看日本二区| 国产精品成人在线| 少妇熟女欧美另类| 亚洲av中文av极速乱| 人妻系列 视频| 国产黄色免费在线视频| 国产精品99久久99久久久不卡 | 亚洲欧美一区二区三区国产| av网站免费在线观看视频| 午夜福利视频1000在线观看| 人体艺术视频欧美日本| 亚洲国产最新在线播放| 精品国产一区二区三区久久久樱花 | av专区在线播放| 麻豆国产97在线/欧美| 免费人成在线观看视频色| 少妇的逼好多水| 日韩欧美一区视频在线观看 | 亚洲av成人精品一区久久| 亚洲av.av天堂| 久久久a久久爽久久v久久| 99久久中文字幕三级久久日本| 亚洲精品乱码久久久v下载方式| 五月伊人婷婷丁香| 成人鲁丝片一二三区免费| 亚洲精品视频女| 久久久久精品性色| av网站免费在线观看视频| 亚洲国产色片| 亚洲av日韩在线播放| 一本一本综合久久| 日本-黄色视频高清免费观看| 久久午夜福利片| 成人免费观看视频高清| 欧美zozozo另类| 日韩,欧美,国产一区二区三区| 亚洲av电影在线观看一区二区三区 | 91狼人影院| 91久久精品国产一区二区三区| 日韩一区二区视频免费看| 夫妻午夜视频| 久久久欧美国产精品| 狂野欧美激情性xxxx在线观看| 国产成人午夜福利电影在线观看| av一本久久久久| 18+在线观看网站| 听说在线观看完整版免费高清| 亚洲无线观看免费| 深爱激情五月婷婷| 欧美激情国产日韩精品一区| 天美传媒精品一区二区| 亚洲国产日韩一区二区| 午夜福利视频精品| 精品熟女少妇av免费看| 中文乱码字字幕精品一区二区三区|