打顶后施用生长素和钾肥对烤烟根系性状及品质的影响

研究了不打顶(T1)、打顶(T2)、打顶+追施K₂SO₄(T3)、打顶+涂抹生长素1次(T4)、打顶+追施K₂SO₄+涂抹生长素1次(T5)、打顶+追施K₂SO₄+涂抹生长素2次(T6)共6种调控措施对烤烟根系性状、ATP酶活性、烟碱和钾含量、烤后烟叶中性挥发性致香物质含量及经济性状的影响。结果表明:与T2相比,打顶后30d根系干重的增幅依次为:T6(52.76%) > T5(22.33%) > T3(10.11%) > T4(8.55%),T3、T5、T6的根系活力明显提高,T6的ATP酶活性远高于其他处理。涂抹生长素和追施K₂SO₄肥对根系烟碱的合成具有一定的抑制作用;与T2相比,在打顶后30d烟碱的降幅依次为:T4(35.09%) > T6(31.58%) > T5(24.56%) > T3(15.79%)。随生育进程延长,根系吸收钾的能力逐渐降低;与T1相比,在打顶后30d各处理烤烟根系钾含量降幅依次为:T2(63.41%) > T4(60.98%) > T3(56.10%) > T5(50.00%) > T6(47.56%)。T6中性致香物质总量最高,各项经济指标值较优。打顶当天在茎断面涂抹生长素,并于根部灌施K₂SO₄肥,促进了烤烟根系生长和品质形成。      

猕猴桃果实中酚类物质的分离鉴定及抗氧化活性

采用高速逆流色谱与制备型高效液相色谱联用技术对猕猴桃果实中酚类化合物进行分离,共获得8 种化合物。利用波谱方法鉴定出7 种化合物,分别为：新绿原酸（化合物1）、咖啡酸-3-O-葡萄糖苷（化合物2）、2-O-咖啡酰基苏糖酸（化合物3）、表儿茶素（化合物5）、原花青素C1（化合物6）、Malaxinic acid（化合物7）、槲皮苷（化合物8）。化合物4经初步推测为B-型原花青素二聚体。化合物2、5、6、7对1,1-二苯基-2-三硝基苯肼和2,2’-联氮-二-(3-乙基-苯并噻唑-6-磺酸)阳离子自由基都有清除效果,清除能力排序为：原花青素C1＞表儿茶素＞咖啡酸-3-O-葡萄糖苷＞Malaxinic acid。     

红枣片热风干制过程中特征香气活性化合物的确定及表征

采用顶空-固相微萃取-气相色谱-嗅闻-质谱联用技术,结合感官分析和偏最小二乘回归（partial least squares regression,PLSR）分析方法,对热风干制过程中不同条件制备的7 个红枣片样品特征香气活性化合物进行了测定及表征。结果表明,红枣片主要挥发性成分为19 种酯类、15 种酮类、15 种酸类、12 种醛类、9 种醇类、6 种烃类和2 种呋喃类化合物。共识别出18 种香气活性化合物气味活度值大于1,包括7 种酮类、4 种醛类、3 种酯类、2 种酸类、1 种醇类和1 种呋喃类物质。感官评价表明,经过热风干制的红枣片中主要特征香气为焦糖香、烤甜香、焦苦味和焦煳味。通过PLSR明确了感官属性与香气化合物之间的相关性：2,3-丁二酮和3-羟基-2-丁酮与烤甜香呈显著正相关;而γ-丁内酯、4-环戊烯-1,3-二酮和2,5-二甲基-4-羟基-3(2H)-呋喃酮对焦糖香有显著贡献;5-甲基呋喃醛和5-甲基-2(5H)-呋喃酮与焦苦味呈正相关;5-羟甲基呋喃醛是焦糊味特性的主要来源;3-羟基-2-甲基-4H-吡喃-4-酮、4H-吡喃-4-酮和2,3-二氢-3,5-二羟基-6-甲基与焦糊味及焦苦味都呈正相关。上述相关性均在感官评价员通过嗅闻仪闻到的具体味道中得到证实。     

催化剂对造纸污泥热解特性的影响

研究了Na2CO3、Na2SO4、NaCl、K2CO3、K2SO4、KCl 6种化合物对造纸污泥热解的催化作用,利用热天平分别将其按一定比例与污泥混合后进行热重实验,对加入催化剂的污泥与空白污泥的DTG曲线进行了分析比较,探讨了催化剂的种类、用量等因素对污泥热解特性的影响。研究结果表明：钠化合物的催化作用大小依次为Na2CO3〉Na2SO4〉NaCl,而钾化合物的催化作用依次为K2CO3〉K2SO4〉KCl,两类化合物中碳酸盐的催化作用显著;6种催化剂均使污泥热解反应向低温区移动,其中碳酸盐最显著,且最大失重速率最大;催化剂用量5%（以催化剂中Na或K元素对污泥质量分数计）时为理想用量。     

基于感官模糊综合评价法与价值工程评价法的市售烤羊肉质量分析评价

基于5组市售烤羊肉样本采用烤羊肉的感官模糊综合评价法（fuzzy comprehensive sensory evaluation,FSE）以及价值工程评价法（value engineering evaluation,VEE）,在感官评分与气相色谱-质谱联用（gas chromatography-mass spectrometry,GC-MS）检测的基础上,以量化及直观的形式表征不同组分挥发性有机化合物（volatile organic compounds,VOCs）对烤羊肉感官属性贡献率的差异,通过主成分分析（principal component analysis,PCA）比较两种方法得到结果的差异,并探究感官模糊指标与价值功能得分之间的相关性,以获得综合评价排序。结果表明：以GC-MS为检测手段鉴定出烤羊肉的42 种VOCs,依据不同属性可以将所有VOCs大致分为Z1（萜烯类和醇类）、Z2（醛类和含硫含氮化合物）、Z3（醚类和酮类）、Z4（芳香类和其他）4 个价值功能组分,且5 组市售烤羊肉样品的功能指数排序为SS4（26.18%）＞SS1（22.53%）＞SS2（19.59%）＞SS3（17.26%）＞SS5（14.43%）;FSE与VEE对5 组样品的评价排序大致相同,通过FSE发现5 组样品综合得分排序为SS4＞SS1＞SS2＞SS5＞SS3;采用PCA对两种方法所得结果综合分析后发现评价排序与采用VEE得出结论一致。VEE的使用一定程度上弥补了FSE中由边界模糊带来的不足,可以作为食品品质监控的价值评判标准,同时采用两个模型能更好地对烤羊肉综合品质进行分析评价。     

Cosmetic preservation and structure-activity relationships of 4-diazo-pyrazole-5-carboxamides

Diazoles have attracted considerable attention for a long time owing to their potentially interesting chemical, biochemical, and medicinal properties. We have reported the synthesis and in vitro antibacterial activity of a new series of ( N -substituted)-3-methyl-4-diazo-5-pyrazolecarboxamides 1a-n along with their quantitative structureactivity study. There was a trend towards a better Gram-negative activity with decreasing molecular refraction values of the substituents on the carboxamidic moiety and a better Gram-positive activity with increasing values of IR carbonyl shift. The compounds which displayed the broadest antibacterial spectrum were 3-methyl-4-diazo-5-pyrazolecarboxamides substituted with 2-pyridinyl and 3-isoxazolyl moieties, making evident the structural requirement of a heterocyclic substituent with aminic function located in the ortho position with respect to heteroatom(s). The introduction of new substituents with different lipophilic properties in place of the C₃-methyl group such as cyano, methoxy, ethoxy, benzyloxy substituents have been examined followed by application of these materials to the cosmetic formulations. An emulsion utilizing the 2-pyridinyl compound at 0.2% and 0.4% has been prepared, and their specific antimicrobial activity has been evaluated. Preliminary antimicrobial challenge studies indicated the excellent preservative activity of this compound in cosmetic formulations.     

栽培菊苣籽总黄酮的细胞毒性及清除羟自由基活性成分的识别

采用3-(4,5-二甲基噻唑-2)-2,5-二苯基四氮唑溴盐(3-(4,5-dimethyl-2-thiazolyl)-2,5-diphenyl-2-H-tetrazolium bromide,MTT)法评价栽培菊苣籽总黄酮对小鼠巨噬细胞RAW264.7的毒性。从总抗氧化能力、清除2,2’-联氮-双-(3-乙基苯并噻唑啉-6-磺酸)二铵盐自由基(2,2’-azino-bis-(3-ethylbenzothiazoline-6-sulfonic acid)diammonium salt cation radical,ABTS+·)能力、清除O_2~-·能力以及抑制Fe~(2+)诱发的卵黄脂蛋白脂质过氧化能力4个方面评价栽培菊苣籽总黄酮的抗氧化活性,并与常见的抗氧化剂VC和叔丁基对苯二酚(tertbutylhydroquinone,TBHQ)作比较。之后采用高效液相色谱(high-performance liquid chromatography,HPLC)法对栽培菊苣籽总黄酮中清除·OH的活性成分进行了识别。MTT实验结果显示,菊苣籽总黄酮质量浓度为1 mg/mL时,对RAW264.7细胞具有一定的毒性,而当其质量浓度适当减小后,则基本无毒性。抗氧化实验结果表明:栽培菊苣籽总黄酮的总抗氧化活性和清除ABTS~+·的能力弱于VC和TBHQ,但在低质量浓度时,其总抗氧化活性与TBHQ非常接近;在清除O_2~-·方面,活性由强到弱为VC菊苣籽总黄酮TBHQ;在抑制卵黄脂蛋白脂质过氧化实验中,栽培菊苣籽总黄酮强于VC,但弱于TBHQ。HPLC法结果显示,绿原酸比洋蓟素具有更高的清除·OH的活性,且二者对·OH的清除率分别为66.42%和46.00%。     

Isolation and Structure-Activity Relationship of the Antioxidant Chemical Constituents from the Flowers of Rosa chinensis Jacq

The objective of this study was to investigate the antioxidant activity, chemical constituents, and structure-activity relationship from the flowers of Rosa chinensis Jacq. The antioxidant activity of the different polar solvent extracts were assayed by a 1,1-diphenyl-2-picrylhydrazyl scavenging experiment. The extract with the strongest 1,1-diphenyl-2-picrylhydrazyl scavenging capacity was further isolated and purified by column chromatography. The structures of the isolated compounds were elucidated on the basis of spectral analysis and physiochemical properties. The antioxidant activity of these compounds was assayed by a 1,1-diphenyl-2-picrylhydrazyl scavenging experiment and ascorbic acid was chosen as the positive control. The ethyl acetate fraction had the strongest 1,1-diphenyl-2-picrylhydrazyl scavenging activity. Ten compounds were obtained, represented as: 3,4,8,9,10-pentahydroxydibenzo[b,d]pyran-6-one (1), quercetin (2), kaempferol (3), 3,5,7,4′-tetrahydroxy-8-methoxy-flavone (4), isoquercetrin (5), kampferol 3-O-β-D-glucoside (6), tiliroside (7), kampferol 3-O-(6′′-galloyl)-β-D-glucoside (8), kampferol 3-O-(2′′,6′′-digalloyl)-β-D-glucoside (9), quercetin 3-O-(2′′,6′′-digalloyl)-β-D-glucoside (10). The 1,1-diphenyl-2-picrylhydrazyl scavenging capacity for these compounds, in descending order, were as follows: 10 > 9 > 1 ≈ 8 > 5 > ascorbic acid ≈ 2 > 6 > 7 > 3 > 4. Compounds 1, 8, 9, and 10 have the stronger antioxidant activity. Our results suggested the antioxidant activities of these compounds might be influenced by the number and position of hydroxyl groups in their aromatic rings.     

Isolation and Identification of Antioxidant Compounds from Gynura Bicolor Stems and Leaves

The antioxidant compounds in the stems and leaves of Gynura bicolor were studied. 1,1-diphenyl-2-picrylhydrazyl and 2,2′-azinobis(3-ethylbenzothiazoline-6-sulfonic acid) radical scavenging assays were employed to evaluate antioxidant capacity. By solvent extraction and Sephadex LH-20 column chromatography in sequence, ethanol extracts of Gynura bicolor stems and leaves were fractionated to obtain their active fractions, which were further separated to obtain 12 compounds: 1–8 from stems, and four, 8–12, from leaves. Their structures were elucidated on the basis of spectroscopic data (nuclear magnetic resonance and mass spectrometry). Among these substances, compounds 1, 2, 3, 4, and 8 with significant antioxidant activity were determined to be responsible active components for stems, and compounds 4, 8, and 12 for leaves.     

Antibodies to the quinolones and fluoroquinolones for the development of generic and specific immunoassays for detection of these residues in animal products

Several quinolone and fluoroquinolone haptens have been used to raise polyclonal antibodies exhibiting both specific and generic properties for these classes of antimicrobial compounds. The antisera have been assessed in rapid enzyme immunoassays (ELISAs) designed to exploit the specificities obtained. A direct generic ELISA for both the quinolones and fluoroquinolones has been developed that uses the cross-reactivity of an antibody raised against norfloxacin (1-ethyl-6-fluoro-1,4-dihydro-4-oxo-7-(1-piperazinyl)-3-quinoline carboxylic acid) linked to ovalbumin via a secondary amine group on the piperazinyl moiety to detect nine different drugs in these classes. Specific ELISAs to ciprofloxacin (1-cyclopropyl-6-fluoro-1,4-dihydro-4-oxo-7-(1-piperazinyl)-3-quinoline carboxylic acid), enrofloxacin (1-cyclopropyl-7-(4-ethyl-1-piperazinyl)-6-fluoro-1,4-dihydro-4-oxo-3-quinoline carboxylic acid), flumequin (9-fluoro-6,7-dihydro-5-methyl-1-oxo-1H,5H-benzo(ij)quinolizine-2-carboxylic acid) and nalidixic acid (1-ethyl-1,4-dihydro-7-methyl-4-oxo-1,8-naphthyridine-3-carboxylic acid) have also been developed with a high degree of specificity to the individual compounds. The assays measure drug residues in bovine milk and ovine kidney with an interassay relative standard deviation (s r ) of 10.5% or less and intra-assay s r of 11.2% or less. Sensitivity is less than 4 μg kg -1 for both the generic and specific assays for all but one of the compounds tested. (Pipemidic acid (8-ethyl-5,8-dihydro-5-oxo-2-(1-piperazinyl)pyrido(2,3-d)pyrimidine-6-carboxylic acid) is detectable at 6 μg kg -1 in kidney.)     

甘氨酸降低复合菌快速发酵虾酱中的组胺含量

降低组胺及提高风味是快速发酵虾酱产业化面临的瓶颈问题。为探讨甘氨酸对快速发酵虾酱中组胺生成的抑制作用及风味品质影响,本研究以新鲜虾头为原料,添加Pichia gilliermondii、Aspergillus niger及Lactobacillus planticola(1:3:5)的复合菌相发酵剂,检测添加甘氨酸后组胺含量变化,追踪对发酵过程中理化性质及安全指标影响,感官评定及电子鼻分析虾酱品质及风味。结果表明,甘氨酸的添加对组胺生成有良好的抑制作用,向虾酱中添加2%、4%和6%的甘氨酸分别使组胺含量降低了29.53%、31.16%和34.98%,随甘氨酸添加量的增加,虾酱中AA-N含量增加,pH降低,菌落总数维持在3.77~4.15 lg(cfu/g)之间,产品安全性良好。甘氨酸添加量为4%时,含硫化合物及芳香化合物传感器响应值增大,增强了虾酱的特征性风味,提高营养及感官风味水平。定量添加的甘氨酸,既提高了产品的风味品质,又在一定程度上降低了组胺含量,保障产品安全性。     

姜黄醇提物化学成分及其抗氧化活性分析

目的：研究姜黄（Curcuma longa L.）的化学成分及其抗氧化活性。方法：应用硅胶柱色谱、Sephadex LH-20凝胶柱色谱以及高效液相制备色谱等方法进行分离纯化,根据高分辨质谱、核磁共振谱鉴定化合物的结构;同时采用1,1-二苯基-2-三硝基苯肼（1,1-diphenyl-2-picrylhydrazyl,DPPH）法、2,2’-联氮双(3-乙基苯并噻唑啉-6-磺酸)（2,2'-azino-bis(3-ethylbenzothiazoline-6-sulfonic acid),ABTS）法和铁氰化钾还原法对分离得到的化合物进行抗氧化活性筛选。结果：从姜黄中分离鉴定了7 个合物,分别为Zingerol（1）、Dihydroferulic acid ethyl ester（2）;乙基-3-(4-羟基-苯基)-丙酸乙酯（3）、Zingerone dimer [4,4’-(6,6’-dihydroxy-5,5’-dimethoxy-[1,1’-biphenyl]-3,3’-diyl) bis(butan-2-one)]（4）、姜酮（5）、4-(3,4-二甲氧基苯基)丁烷-2-酮（6）、香草醛（7）。其中,化合物1～5均具有一定的抗氧化活性,ABTS阳离子自由基清除实验中,化合物1和化合物2的IC50值分别为（3±0.2）μmol/L和（12±1.0）μmol/L,化合物1优于阳性对照VC（VC的IC50值（13±1.1）μmol/L）,化合物2与VC效果相当,还原力实验中,化合物1活性优于VC,浓度低于0.125 μmol/mL时化合物2活性强于VC。结论：化合物4为新的天然产物,化合物1、2、3和6为姜黄属中首次发现,化合物1抗氧化活性较强可能与其脂肪链2位上羟基取代有关,姜黄醇提物中的酚类成分是姜黄抗氧化活性的物质基础之一。     

铵盐对紫色红曲霉合成代谢红曲色素及桔霉素的影响

研究紫色红曲霉（Monascus purpureus）Y20液态发酵过程中不同铵盐对目的产物红曲色素及有害物质桔霉素的合成代谢的影响。在发酵培养基中添加不同铵盐,检测M. purpureus Y20发酵液中红曲红色素、红曲黄色素及桔霉素含量,分析其变化及原因。结果表明：M. purpureus Y20发酵过程中发酵液pH值相对较稳定,未添加铵盐的对照组发酵液基本维持在pH 4.8;添加CH3COONH4、NH4H2PO4、C6H5O7(NH4)3的发酵液pH＞6;添加NH4NO3、(NH4)2SO4、NH4Cl的发酵液初始pH＜5.5,发酵过程中持续降低至pH 2.5左右;含有0.3 mol/L NH4＋的(NH4)2SO4的发酵液中桔霉素含量降为0.05 mg/L,较对照组降低88.6%;含有0.1～0.3 mol/L NH4＋的NH4Cl发酵液中桔霉素含量降为0.05 mg/L;含有0.3 mol/L NH4＋的NH4NO3发酵液未检出桔霉素,红曲黄色素含量较对照组升高31.0%、红曲红色素含量降低11.6%;添加CH3COONH4、NH4H2PO4、C6H5O7(NH4)3的发酵液无桔霉素检出,但菌体干质量较小,色价较低。因此,添加铵盐可影响发酵液pH值,影响M. purpureus Y20对营养物质吸收和代谢,改变红曲色素的组成比例和抑制桔霉素的生成;添加适量(NH4)2SO4、NH4Cl、NH4NO3有利于促进红曲黄色素的生物合成,阻碍桔霉素的生成。     

花椒果皮多酚类成分鉴定及降血糖活性

以花椒果皮为研究对象,通过乙醇提取得到花椒果皮粗多酚,再采用分级萃取,依次得到二氯甲烷相（F1）、乙酸乙酯相（F2）、正丁醇相（F3）和水相（F4）,采用超高效液相色谱-电喷雾飞行时间串联质谱法分析其酚类物质组成,通过对α-葡萄糖苷酶的抑制作用以及II型糖尿病模型小鼠评价其降糖活性。结果从花椒果皮中共鉴定出20种多酚类化合物,包括9种酚酸及其衍生物和11种黄酮类化合物。各相中总酚、总黄酮及多酚类化合物含量的变化趋势为F2>F3>F4>F1,说明分级萃取对多酚类物质能起到良好的富集作用。花椒果皮多酚对α-葡萄糖苷酶活性有抑制作用,其中F3的抑制率最高可以达到85.86%,且是通过反竞争性抑制的方式抑制α-葡萄糖苷酶活性,F3中的主要活性成分绿原酸和芦丁与α-葡萄糖苷酶活性的抑制率显著正相关。F3能使糖尿病小鼠的空腹血糖降低64.2%,口服糖耐量降低21.42%,对小鼠的体质量和饮食异常也有一定改善作用。因此花椒果皮多酚有望成为具有预防和治疗糖尿病潜质的活性成分。     

基于电子鼻和气相色谱-质谱法结合相对气味活度值分析植物油对红油辣椒气味的影响

目的 为探究植物油对红油辣椒气味的影响。方法 采用电子鼻、气质联用技术(gas chromatography-mass spectrometry,GC-MS)结合正交偏最小二乘判别分析(orthogonal partial least squares discriminant analysis,OPLS-DA)和相对气味活度值(Relative Odor Activity Value,ROAV)等分析方法探究不同品种的植物油对红油辣椒气味物质的影响。结果 电子鼻检测结果结合OPLS-DA分析表明不同品种的植物油制备的红油辣椒其整体气味轮廓差异明显。GC-MS检测结果表明5种植物油制备的红油辣椒共检测到101种挥发性物质,其中醇类29种、醛类30种、烃类12种、硫醚类3种、酯类6种、酸类2种以及其他化合物19种；醇类、醛类、硫醚类是红油辣椒的主要挥发性物质。ROAV分析表明A样品(精炼菜籽油)的关键性化合物是：苯乙醛、反-2-壬醛、二甲基硫醚；B样品(大豆油)的关键性化合物是：1-庚烯-3-酮、二甲基硫醚；C(花生油)、E(菜籽油)样品的关键性化合物是：二甲基硫醚; D(玉米油)样品的关键性化合物是：二甲基硫醚、(Z)-2-壬烯醛、1-辛烯-3-酮。结论 不同品种的植物油制备的红油辣椒的主要挥发性物质有一定差,二甲基硫醚是红油辣椒的共有关键性化合物。     

Creatin(in)e and Maillard reaction products as precursors of mutagenic compounds: Effects of various amino acids

The participation of creatin(in)e and Maillard reaction products in developing mutagenic activity was studied in model systems. Glucose and an amino acid were boiled under reflux for 2 h at 130°C together with creatine or creatinine dissolved in water-diethylene glycol (1:6). Threonine produced the highest mutagenic activity, 1068 revertants per μmol amino acid, towards TA98 after S9 activation, followed by glycine (410 rev/μmol) and lysine (246 rev/μmol). Proline, glutamic acid and the sulfur-containing amino acids produced less than 40 rev/μmol. Protein-bound amino acids produced no detectable mutagenic activity. When added to the reaction mixtures, the pure Maillard reaction products increased the mutagenic activity significantly. All precursors used occur in free form in meat. Work is now in progress to identify the mutagenic compounds produced in the model systems and to establish whether they also occur in fried meat.     

基于GC-MS探究郫县豆瓣和豆豉对盐煎肉挥发性风味物质的影响

利用顶空-固相微萃取-气质连用（HS-SPME-GC-MS）,采用化学计量学方法探究郫县豆瓣和豆豉对经典川菜盐煎肉挥发性风味成分的影响,根据气味活度值（OAV值）确定盐煎肉的关键风味物质。结果表明:GC-MS共检测到137种挥发性风味物质,其中烃类21种,醇类12种,酚类6种,醚类8种,醛类22种,酮类6种,酸类6种,酯类12种,杂环类40种,其他4种。未添加郫县豆瓣和豆豉的样品为空白对照组,即样品1;豆瓣和豆豉单独添加时,m（豆瓣）=8 g为样品2;m（豆豉）=10 g为样品3;当豆瓣和豆豉混合添加总质量为18 g,通过不同混合比例设置样品4~样品7,具体为:豆瓣:豆豉=3:6为样品4;豆瓣:豆豉=4:5为样品5;豆瓣:豆豉=6:3为样品6;豆瓣:豆豉=7:2为样品7。样品1~样品7中含有的挥发性风味化合物种数及浓度依次为:60、64、63、72、57、66、69种,78.08、250.77、71.22、85.62、116.12、44.43、55.77 μg/kg。对OAV值的分析显示,7种样品共有的关键风味物质是:2-辛醇、桉叶油素、己酸、2, 5-二甲基吡嗪、2, 5-二甲基-3-乙基吡嗪。主成分分析（PCA）显示,样品5的PCA_1（99.18%）和PCA_2（0.19%）与其他实验样品存在明显差异,与感官轮廓相符,样品5接受度最高。因此,样品5中的郫县豆瓣和豆豉为最佳风味配比。     

红曲菌发酵对低盐半干鲩鱼的提味增鲜作用

为探究红曲菌发酵对低盐半干鲩鱼的增鲜作用,在传统低盐半干鲩鱼工艺上引入红曲菌发酵技术,以普通低盐半干鱼组和添加灭活红曲菌发酵剂的低盐半干鱼组（添加灭活发酵剂组）作为对照,通过水可溶性氮、三氯乙酸可溶性氮两指标分析蛋白的降解程度,游离氨基酸和5’-核苷酸含量计算滋味活性值和味精当量。结果表明：红曲菌发酵后的半干鱼产品滋味更加鲜美醇厚,色泽红润诱人;产品中蛋白质大量降解,水可溶性氮、三氯乙酸可溶性氮含量显著增加;红曲菌发酵半干鱼样品的味精当量达到7.34?g/100?g,是红曲菌未发酵半干鱼样品的4.38?倍;总游离氨基酸,特别是谷氨酸和天冬氨酸等鲜味氨基酸的含量明显增加,5’-鸟苷酸和5’-肌苷酸等呈鲜核苷酸含量也明显提高;并且5’-鸟苷酸与谷氨酸的滋味活性值均大于1,表明红曲菌发酵对低盐半干鱼具有明显提味增鲜作用,其中5’-鸟苷酸与谷氨酸是影响产品鲜味的2 个主要成分。     

A Review on Structure–Activity Relationship of Dietary Polyphenols Inhibiting α-Amylase

The inhibitory effects of dietary polyphenols against α-amylase have attracted great interest among researchers. The aim of this review is to give an overview of the research reports on the structure–activity relationship of polyphenols inhibiting α-amylase. The molecular structures that influence the inhibition are the following: (1) The hydroxylation of flavonoids improved the inhibitory effect on α-amylase; (2) Presence of an unsaturated 2,3-bond in conjugation with a 4-carbonyl group has been associated with stronger inhibition; (3) The glycosylation of flavonoids decreased the inhibitory effect on α-amylase depending on the conjugation site and the class of sugar moiety; (4) The methylation and methoxylation of flavonoids obviously weakened the inhibitory effect; (5) The galloylated catechins have higher inhibition than nongalloylated catechins; the catechol-type catechins were stronger than the pyrogallol-type catechins; the inhibition activities of the catechins with 2,3-trans structure were higher than those of the catechins with 2,3-cis structure; (6) Cyanidin-3-glucoside showed higher inhibition against than cyanidin and cyanidin-3-galactoside and cyanidin-3,5-diglucoside had no inhibitory activity; (7) Ellagitannins with β-galloyl groups at glucose C-1 positions have higher inhibitory effect than the α-galloyl and nongalloyl compounds and the molecular weight of ellagitannins is not an important element.     

Fru-Gly化合物的合成条件优化及其抗氧化活性

在单因素的基础上,利用响应面法对葡萄糖和甘氨酸反应体系合成1-脱氧-1-L-甘氨酸-D-果糖(Fru-Gly)的合成条件进行优化,并对其抗氧化活性进行研究。在不同反应时间、反应温度及葡萄糖与氨基酸不同物质的量比的条件下合成Fru-Gly化合物,比较不同反应条件对反应体系生成Fru-Gly化合物的浓度及其褐变程度的影响,并检测其浓度与清除1,1-二苯基-2-三硝基苯肼(DPPH)自由基能力、清除2,2'-联氮-二(3-乙基苯并噻唑啉-6-磺酸)二铵盐(ABTS)自由基能力、还原能力的相关性。结果表明,合成Fru-Gly化合物的最优条件为:反应时间0.9 h,反应温度79℃,葡萄糖和甘氨酸物质的量比3.25∶1,此时样品的3种抗氧化活性均最强。相关性分析表明,Fru-Gly化合物的浓度与DPPH自由基清除力、ABTS自由基清除力以及还原力互为极显著正相关,且相关性系数均大于0.96。