发光二极管蓝光对乙烯褪绿早熟蜜橘果实叶绿素代谢的调控作用

重庆当地早熟蜜橘存在果皮晚于果肉达到成熟标准的特点,为解决这个问题,柑橘产业中常用乙烯对蜜橘果实进行褪绿处理。但单独乙烯褪绿蜜橘果实着色浅,感官品质不佳,影响消费者接受度。基于此,前期研究探讨了光照对乙烯褪绿蜜橘果实着色的影响,发现以300 lx、450 nm发光二极管（light-emitting diode,LED）蓝光处理能有效改善乙烯褪绿蜜橘果实的色泽,并从类胡萝卜素代谢角度对其机理进行了初步研究。鉴于蜜橘果实色泽的形成是由叶绿素和类胡萝卜素共同决定的,本实验通过对叶绿素相关基因表达水平和代谢物质含量变化分析探讨蓝光和乙烯协同处理对蜜橘果皮叶绿素代谢的调控作用。结果表明,蓝光和乙烯协同处理通过促进蜜橘果皮叶绿素降解相关基因CcRCCR、CcNYC1上调表达和叶绿素合成相关基因CcCAO、CcChIH、CcMPEC下调表达,促进果实中叶绿素a、叶绿素b、脱镁叶绿素a、脱镁叶绿酸甲酯a、脱镁叶绿酸甲酯b的降解,从而加速果实转色。研究结果可为系统阐述蓝光和乙烯协同调控蜜橘果实着色的机理提供一定的理论参考。     

黄金芽茶鲜叶加工过程中色泽变化及内在原因分析

探究黄金芽茶鲜叶加工过程中的色泽变化及其内在原因,以期为黄金芽及此类白化茶树品种鲜叶的加工生产提供一定理论指导。以常规茶树品种鸠坑作为对照,分析黄金芽鲜叶在受热加工过程中外观色泽和内在呈色物质含量的变化,采用UPLC法分析叶黄素、β-胡萝卜素、叶绿素a、叶绿素b、脱镁叶绿素a及脱镁叶绿素b等6种脂溶性色素含量。研究结果表明,黄金芽鲜叶杀青后外观颜色由黄变绿,色差a*值由正值(红色)变为负值(绿色),以叶黄素为代表的黄色素含量显著降低,导致绿色素与黄色素含量比值显著上升,呈现鲜绿色;而后续的闷黄工序可使茶叶外观色泽恢复黄色,原因在于闷黄可使茶叶中的叶绿素a/b含量显著下降,绿色素与黄色素含量比值显著降低,使得闷黄后的成品茶外观色泽和色素含量均与鲜叶更为接近,黄金芽鲜叶的色泽优势由此得以凸显。     

基于UPLC-Q-Exactive Orbitrap-MS分析不同足火方式对绿茶中叶绿素降解的影响

探索不同足火方式（远红外足火、微波足火、提香机足火、理条足火、六角辉锅足火）对绿茶色泽和叶绿素降解的影响。建立基于超高效液相色谱-四极杆-静电场轨道阱高分辨质谱联用技术分析茶叶中叶绿素组分及其降解衍生物方法,可在20 min内检测19 种叶绿素及降解组分,并较好分离6 对差向异构体,且预处理简单。将该方法用于5 种不同足火方式所制绿茶中叶绿素及其降解组分的检测分析,并结合正交偏最小二乘法判别分析及单因素方差分析,探究不同足火方式对绿茶叶绿素降解的影响。结果显示,微波足火所制绿茶色泽感官品质和色泽属性均优于其他足火方式。微波足火所制得绿茶中叶绿素a、叶绿素b、叶绿素a’、叶绿素b’等含量最高,而降解产物焦脱镁叶绿酸a、焦脱镁叶绿酸b、焦脱镁叶绿素a、焦脱镁叶绿素b含量最低,表明微波足火过程中绿茶发生异构化、脱镁降解反应、脱羧甲基化反应的程度均低于其他足火方式,故微波足火更有利绿茶中叶绿素的保留。本研究可为绿茶品质提升和定向化加工提供理论基础和技术指导。     

PH值对加热绿色蔬菜中叶绿素锌形成的影响──亨特Lab色度法

绿色蔬菜热加工过程中，细胞内酸性物质释放及新酸生成，使绿色叶绿素脱镁形成黄褐色的脱镁叶绿素与进而脱甲酯基的焦脱镁叶绿素。为顺应消费者的嗜绿心态，本世4O年代以来，人们一直在寻求保持绿色的办法。加碱（如MPCO3）升高PH、短时高温、叶绿酶水解掉叶绿醇基、及多法共用，都能不同程度地保持加工过程的绿色，但一经存放，绿色仍不能保持。1943年Newburger报道罐装秋葵再生出斑点状特绿（vert一sreen），Fischbach将之归因于含Zn叶绿素。由此．叶绿素衍生物绿色的金属配合物研究广泛开展。叶绿素分子的发色团是带天然取代基的叶吩…     

高浓度CO_2对香蕉和大蕉后熟及果皮叶绿素降解的影响

以香蕉和大蕉为试材,在20%CO_2+21%O_2气调环境和20℃的后熟条件下,通过测定叶绿素含量、果实硬度、细胞膜透性、丙二醛含量、叶绿素酶和脱镁螯合酶活力来研究高浓度CO_2对香蕉和大蕉后熟和果皮叶绿素降解的影响。结果表明:20%CO_2对香蕉和大蕉的后熟和叶绿素b含量均无显著影响,但对叶绿素a含量的影响不同,相比于大蕉,香蕉果皮叶绿素a的降解受到明显抑制;叶绿素酶不是香蕉和大蕉叶绿素降解的关键酶;20%CO_2明显抑制了香蕉脱镁螯合酶的活力,但大蕉脱镁螯合酶的活力反而提高,脱镁螯合酶是香蕉叶绿素降解过程中的关键酶。可见,相比于大蕉,香蕉果皮的褪绿更容易受到高浓度CO_2的贮藏环境的影响。     

基于叶绿素的果蔬护绿方法研究进展

叶绿素是存在于绿色植物中的一种独特而重要的营养物质,在果蔬贮藏与加工过程中,如何保护叶绿素是一大难题.本文对叶绿素的性质、叶绿素稳定性的影响因素及果蔬护绿技术等进行了综述.     

光照对鲜青花椒干燥过程中叶绿素降解的影响

以鲜青花椒为原材料,研究在3种单色光黄光、蓝光、紫外光以及日光(复合光)对鲜青花椒干燥过程中色泽和叶绿素及其衍生物含量的变化,以确定光照对鲜青花椒干燥过程中叶绿素降解的影响。结果表明:在整个干燥过程中,鲜青花椒果皮的绿色逐渐褪去,并逐渐变暗;其中,紫外光作用最显著,能使鲜青花椒由绿色转变为褐色;同时,鲜青花椒的叶绿素均有不同程度的降解,其中紫外光干燥能使叶绿素a和叶绿素b降解57.94%;光照会引起叶绿素衍生物的代谢紊乱,包括脱镁叶绿素a、脱镁叶绿酸a和焦脱镁叶绿酸a,在紫外光和日光照射的干燥中,还会产生少量焦脱植基叶绿素a、焦脱镁叶绿素a以及C132-OH脱镁叶绿酸a等褐色衍生物,这些衍生物的积累可能是造成青花椒色泽劣变的主要原因。     

叶绿素对叶黄素生物可给率的影响

叶黄素具有多种生理活性,它在人体内不能合成,只能从外界获取,但叶黄素因其脂溶性的特点导致生物可给率低,如何高效补充叶黄素成为研究热点。叶绿素常与叶黄素共同出现在人类饮食中,且二者均为脂溶性物质,会产生一定的相互作用。因此研究膳食叶绿素及其结构变化对叶黄素生物可给率的影响具有重要意义。通过制备膳食中常见的8种不同结构的叶绿素（叶绿素a和b、脱镁叶绿素a和b、脱植基叶绿素a和b、脱镁叶绿酸a和b）,采用体外静态消化模型和胶束化实验研究它们对叶黄素生物可给率的影响,并测定叶黄素和叶绿素形成的混合胶束粒径和电位的变化。结果表明,在共消化时不同结构的叶绿素能够显著提高叶黄素的回收率和生物可给率（P<0.05）,其中脱镁叶绿素b的作用最为显著,所对应的叶黄素回收率和生物可给率分别为90.48%和80.44%。在消化过程中,未检测到明显的叶黄素降解产物,而叶绿素的结构则发生了明显的变化。通过消化物和胶束的平均粒径、荧光图像以及Zeta电位值可以确定胶束液体系比消化液体系更稳定,并且叶绿素可以通过与叶黄素形成复合物来保护叶黄素。本研究对如何提高叶黄素的生物可给率及消化利用性能具有一定的指导意义。     

采后猕猴桃叶绿素降解机制及1-MCP处理对其代谢的影响

以陕西"秦美"猕猴桃为试材,在(0.0±0.5)℃贮藏条件下,研究猕猴桃叶绿素的降解机制及1-甲基环丙烯(1-methylcyclopropene,1-MCP)处理对猕猴桃叶绿素及其衍生物和相关酶活的影响。结果表明:在猕猴桃果实贮藏过程中,脱植基叶绿素a、脱镁叶绿素a和脱镁叶绿酸a是叶绿素a的主要降解产物,其含量呈先上升后下降的趋势。脱植基叶绿素a和脱镁叶绿酸a的变化趋势分别与叶绿素酶和脱镁螯合酶活性变化趋势一致,由此推断其降解过程遵循叶绿素脱镁叶绿酸a加氧酶降解途径。1.0 μL/L 1-MCP处理可提高猕猴桃果实过氧化物酶活性,抑制叶绿素酶和脱镁螯合酶的活性,减缓叶绿素的降解,抑制脱植基叶绿素a、脱镁叶绿素a、脱镁叶绿酸a的生成,从而延缓果实绿色的降解以及果实的成熟与衰老。研究结果可为1-MCP延缓猕猴桃果实的褪色提供理论依据。     

软包装野菜护绿工艺探讨

蔬菜之所以为绿色,因在其植物体内有一种叶绿素A的成分,植物生长早期在叶绿素A的四吡咯结构中存在镁,使值物显为绿色。当四吡咯结构中的镁被去除后,生成褐绿色的脱镁叶绿素,为了能使人们喜欢的绿色保存下来,本文从影响叶绿素的脱镁变褐的各个因素出发,对蔬菜护绿工艺做了探讨,包括使用代替叶绿素中镁,而不影响绿色变化的铜,热烫时间,盐腌浓度等多个方面。     

高静压处理对绿芦笋生理特性及贮藏品质的影响

为深入了解高静压（high hydrostatic pressure,HHP）对绿芦笋的保鲜效果,以绿芦笋为原料,探讨了HHP处理对绿芦笋采后生理及贮藏品质的影响。经20、50、100 MPa各保压2 min处理的样品置于相对湿度90%、温度4 ℃的冷库中贮藏15 d。贮藏期间定期测定绿芦笋的呼吸强度、丙二醛含量、细胞膜渗透率、叶绿素变化、嫩茎硬度、总酚含量和质量损失率以及色泽的变化。结果表明：与对照组相比,HHP处理可以有效降低贮藏期间绿芦笋呼吸强度,延缓嫩茎中叶绿素降解,较好保持了绿芦笋的硬度和色泽。研究结果为HHP用于嫩茎蔬菜的保鲜贮藏提供了依据。     

不同制汁工艺对绿芦笋汁理化成分和抗氧化活性的影响

以绿芦笋为材料,研究了直接破碎制汁、热烫后破碎制汁、热烫后破碎经纤维素酶处理制汁、冷冻芦笋解冻后破碎制汁四种工艺对绿芦笋汁理化成分和抗氧化活性的影响。结果表明:热烫处理能保护芦笋汁的色泽,提高VC的稳定性;纤维素酶处理能提高芦笋汁的可溶性固形物、总糖及总黄酮含量及其抗氧化活性;热烫和纤维素酶处理均能降低芦笋汁中的可溶性蛋白和总酚含量。     

INFLUENCE of BLANCHING TREATMENTS ON the TEXTURE and COLOR of SOME PROCESSED VEGETABLES and FRUITS

Fifteen selected vegetables and fruits were processed by conventional procedures with modified blanching conditions. the texture of blanched and processed samples was determined. Low-Temperature-Long-Time (LTLT) blanching considerably increased the final firmness of sterilized carrot, endive and green bean samples, as well as pasteurized cherry samples. After screening experiments, green bean and endive were chosen for further research. Analysis of variance revealed that LTLT blanching treatments in a blanching solution containing calcium and zinc cation significantly affected the texture and color of processed green bean and endive. the blanching treatments were optimized to improve the texture and color of sterilized green bean and endive.     

Degradation Kinetics of Green Color and Chlorophylls in Peas by Colorimetry and HPLC

The kinetics of chlorophyll degradation and visual green color loss in pureed green peas with 80% moisture (w/w) were determined at 70, 80 and 90 C. The –a value from a tristimulus colorimeter was chosen as the physical property and a technique based on fractional conversion was developed in the determination of kinetic parameters of visual green color loss. The degradation of chlorophyll a, chlorophyll b and greenness followed a first order reaction and the temperature dependence of these reactions indicated an Arrhenius relationship. The activation energies were 19.5, 17.1 and 18.2 kcal/mol, respectively.     

COLOR EVALUATION AND CHLOROPHYLL CONTENT IN DRY GREEN PEAS

Tristimulus colorimetry and chlorophyll concentration were used to quantify to color of 34 green-seeded dry pea cultivars grown at two locations in southern Manitoba in 1990 and 1991. The tristimulus color data, expressed as L, a and b, of ground seed were significantly correlated with contents of chlorophyll a and b and total chlorophyll. The hue function tan^?1 b/a was highly correlated with chlorophyll a/b, total chlorophyll and contents of chlorophyll a and b. For whole pea seed, however, tristimulus color values were found to be poorly correlated with chlorophyll content. Tristimulus color evaluation of three green-seeded pea cultivars stored at 10, 25 and 40C and 11, 33, 52 and 75% relative humidity for up to 45 days revealed no significant loss of green color except in samples stored at 40C and 75% relative humidity, which displayed less green and more yellow color.     

Bleaching of Green Peas and Changes in Enzyme Activities of Seeds under Simulated Climatic Conditions

ABSTRACT: The effects of simulated climatic conditions on green color loss of peas ( Pisum sativum ) and related enzyme activities were investigated. Seeds of 2 green pea cultivars showing different resistance to green color bleaching were subjected to light only, soaking in water without light, and soaking in water with light. Green color loss and chlorophyll loss were highest in seeds soaked in water and exposed to light, less in seeds soaked in water under dark conditions, and least in seeds exposed to light only. Increased chlorophyllase activity was associated with loss of green color and chlorophyll, whereas no significant relationship was found between chlorophyll loss and lipoxygenase or chlorophyll-degrading peroxidase activity. Susceptible and resistant cultivars had significant differences in green color, chlorophyll content, chlorophyll a/b ratio, and chlorophyll degradation kinetics constant when seeds were soaked in water and exposed to light. Enzyme activity was not significantly different between the cultivars. Soaking led to more green color loss, chlorophyll breakdown, and chlorophyllase activity than light exposure. Chlorophyllase may be the key enzyme responsible for green pea bleaching instead of the oxidative chlorophyll degradation pathway with lipoxygenase or chlorophyll-degrading peroxidase.     

绿豆衣清爽饮料护色工艺优化

将绿豆芽生产中＂烫豆＂工艺的副产物加工成绿豆衣清爽饮料,依据绿豆衣中叶绿素的保护机理对绿豆浸提的护色工艺进行改进,在单因素实验基础上对护色剂进行复配,采用正交实验设计方法确定最佳护色剂配比,提出了绿豆浸提的最佳工艺为：浸提初始温度80℃,浸提时间20min,护色剂（柠檬酸钠0.20%、异VC钠0.016%、三聚磷酸钠0.05%）,pH7.76。浸提液经高温高压（121℃,20min）杀菌后仍能保持绿豆自然的黄绿色泽。浸提和护色工艺对绿豆籽粒的种子活力影响很小,仍可进行绿豆芽的加工生产。     

PILOT PLANT EVALUATION OF INDIVIDUAL QUICK BLANCHING (IQB) FOR VEGETABLES

A pilot plant IQB blancher was field tested at a California freezing plant. The system included: a warming and drying preconditioning unit, a steam chamber for single layer belt heating, a deep moving-bed holding chamber for temperature equilibration and enzyme inactivation and an air-water spray cooling unit. IQB with and without preconditioning were compared to conventional, steam blanching at equivalent levels of enzyme inactivation in green beans, lima beans, Brussels sprouts and green peas. Effluent volume and total-solids concentration were measured. Product yields were determined by measuring residual peroxidase activity, chlorophyll conversion and ascorbic acid content as well as by sensory panel testing for color and flavor. Results showed that vegetables blanched with IQB and IQB with preconditioning were essentially the same in quality as those blanched at commercial conditions. Solids loss in the effluent was substantially less with IQB and preconditioning than with conventional steam blanching     

热烫处理对罐藏蔬菜的质构和颜色的影响

１１种经过选择的蔬菜采用常规工艺加工但对热烫条件加以修改，然后测定杀菌后的蔬菜样品的质构。试验结果表明，低温长时间热烫可增加７种罐藏蔬菜，即胡萝卜、苣荬菜、甜菜根、韭葱、青刀豆、洋葱和白卷心菜的坚实度，其中４种罐藏蔬菜即胡萝卜、苣荬菜、韭葱和青刀豆的质构可有较大程度的改善。在此基础上选择青刀豆和苣荬菜作深入研究。方差分析表明，在添加Ｃａ￣（２＋）和Ｚｎ￣（２＋）的热汤水中进行低温长时间热烫处理将显著影响罐藏青刀豆和苣荬菜的质构、颜色。对热烫条件的优化可同时改善罐藏青刀豆和苣荬菜的质构和颜色。     

加工工艺对名优绿茶叶素变化的影响

用薄层扫描分析法测定了名优绿茶叶绿素组成的变化。结果表明，在针形茶加工过程中，chla、chlb呈下降趋势，pya、pyb呈上升趋势，cda、cdb变化较小。杀青工序和揉捻后做形前期是叶绿素破坏和脱镁叶绿素形成的主要阶段。主要类型名优绿茶叶绿素测定结果表明，chla、pya差异较大，其次是chlb，而cdb、cda、pyb的差异较小。揉捻对名优茶色泽品质有影响．揉捻型名茶叶绿素的含量低于未揉捻型名茶，而脱镁叶绿素的含量则相反。春茶后期以及夏秋季鲜叶加工过程叶绿素的过多破坏和脱镁叶绿素的大量形成是造成叶色发暗的主要原因。