马杜罗茄衣发酵过程中外观颜色和内在成分的变化及相关性分析

  目的  为探明马杜罗茄衣发酵过程中烟叶外观颜色的变化。  方法  本文以"海南3号"茄衣品种为试验材料，研究了不同厚度烟叶，发酵过程中颜色变化，并结合其内在化学物质的变化进行了相关分析。  结果  （1）不同厚度茄衣烟叶发酵过程中颜色参数值（L*、a*、b*、C）都呈现一致的下降趋势，其中尤以明度值L*下降最为显著。（2）随着发酵时间增加，茄衣中总糖、烟碱和质体色素含量逐渐降低；还原糖与钾含量呈单峰变化；总氮与氯含量波动上升。（3）相关性分析结果表明，颜色参数与各类质体色素含量之间均呈现极显著正相关关系，与多项化学成分间存在显著或极显著相关；典型相关分析结果表明，随着烟叶中叶绿素a、类胡萝卜素含量在一定范围内的降低以及总氮的升高，明度值L*呈降低趋势；而总糖和叶绿素b含量的降低，则引起饱和度C的降低和色相角H°的升高。  结论  茄衣烟叶颜色与化学成分有密切的关系，可以通过发酵促进马杜罗茄衣颜色转深。      

贵州烤烟色素含量和颜色值随生育期的变化及其相关性

为了进一步探讨贵州烤烟生长特性,以K326、毕纳1号、贵烟1号、贵烟2号和K326有机烟为材料,研究了大田生育期（35、70、105 d）烟叶质体色素含量和颜色参数值的变化幵进行了相兲分析。结果表明,生育期烤烟烟叶质体色素含量和颜色参数（H＊除外）值均呈逐渐下降的趋势。毕纳1号35 d和105 d质体色素含量显著高于其他材料;K326有机烟70 d和105 d质体色素含量显著低于其他材料,但其L＊、b＊和C＊值显著高于其他材料。不同烤烟材料生育期烟叶L＊和H＊值差异均显著,且b＊和C＊值105 d显著高于35 d和75 d。不同烤烟材料烟叶质体色素含量与颜色参数值相兲均显著,其中质体色素含量与L＊、a＊值相兲系数较大,在0.805~0.866之间。线性回归分析表明,变量叶绿素b R2值（R^2=0.915）最大,变量类胡萝卜素R2值（R2=0.847）最小;自变量中线性回归系数正值Xa＊最大,其次是XH＊。相对类胡萝卜素,烤烟生育期烟叶叶绿素含量与颜色参数值的线性回归性更好。     

晾制湿度对雪茄茄衣烟叶颜色的影响

为揭示影响雪茄茄衣烟叶颜色的主要因素，采用常规晾制、分阶段取样的方法研究了不同晾制湿度处理雪茄烟叶含水率、叶绿素含量（质量分数）、酶活性、化学成分和色度值的变化规律。结果表明：晾制过程中低湿度处理的雪茄茄衣烟叶失水速度较快，其次为中湿度处理，高湿度处理较慢。在高湿度条件下，雪茄茄衣烟叶叶绿素a和叶绿素b降解较快，类胡萝卜素含量增加较快。过氧化物酶（POD）和多酚氧化酶（PPO）活性高湿度处理高于中湿度和低湿度处理，在晾制后期（20～30 d）更加明显。高湿度处理晾制后雪茄茄衣烟叶色度值较高，中湿度和低湿度处理色度值较低。相关及逐步回归分析表明，雪茄茄衣烟叶还原糖和总氮含量与色度值的相关系数达到极显著（P≤0.01）水平，是影响晾制后茄衣颜色的重要因素。     

烘烤过程中烟叶颜色特征参数与色素含量的关系

为了明确烟叶颜色特征与色素含量的关系,以红花大金元品种不同成熟度烟叶为试验材料,研究了烘烤过程中颜色特征参数和色素含量的变化以及二者间的关系.结果表明,在整个烘烤进程中,烟叶图像的3个颜色特征参数的大小依次为R(彩色数字图像中红色的亮度值)＞G(彩色数字图像中绿色的亮度值)＞B(彩色数字图像中蓝色的亮度值);不同成熟度烟叶R、G、B分量的平均值均表现为过熟＞适熟＞尚熟.烘烤过程中成熟度低的烟叶叶绿素降解速度较快,降解量明显大于成熟度高的烟叶;尚熟烟叶的类胡萝卜素含量在变黄和定色期大量降解,直到定色期结束时与适熟和过熟烟叶的类胡萝卜素含量接近,而过熟烟叶的类胡萝卜素含量下降幅度较小.R值与烟叶叶绿素含量间呈极显著负相关,B值与烟叶类胡萝卜素含量间存在显著负相关;R,G组合和r,g值(颜色分量)均与色素含量有较好的相关性;H(色调)值与烟叶叶绿素和类胡萝卜素含量间均存在极显著的正相关.选取与烟叶色素含量均具有显著相关关系的8个颜色特征参数,即H,g,r-g,G-R,G/R,G/(R+B),(G-R)/(G+R)和(R-G)/(R+G+B)值,建立了对烟叶色素含量的逐步回归方程,经F测验达到极显著水平.因此,烘烤中不同成熟度烟叶颜色特征参数和色素含量的相关性明显,可以用颜色特征参数作为辅助指标来判断烟叶色素含量.     

烤烟成熟过程中鲜烟颜色值与色素含量变化及相关分析

为研究烤烟成熟过程中鲜烟叶颜色值与色素含量的变化以及相关性,测定了各部位4 个成熟度鲜烟叶的颜色值和色素含量,并进行了相关性分析.结果表明,在烟叶成熟过程中,各部位烟叶的亮度值L＊、红度值a＊、黄度值b＊均不断增大,且各部位烟叶不同成熟度间各颜色值差异显著性不同,颜色值变化趋势存在差异,其中,中、上部叶红度a＊值变化较大,增幅显著.各部位烟叶叶绿素a、叶绿素b、总叶绿素、类胡萝卜素含量均逐渐减小,类叶比值不断增大.下、上部叶类叶比值增幅基本保持不变,而中部烟叶黄绿面积在70%～80%到80%～90%时类叶比值增幅较大.各颜色值均与各色素含量、类叶比值呈显著或极显著性相关关系.表明成熟过程中烤烟叶片颜色值与色素含量关系密切,叶片颜色值变化可以指示烟叶各色素含量的变化,可以将色差计作为判断烟叶成熟度的辅助工具.     

山东烤烟烟叶颜色量化分析及与多酚和类胡萝卜素含量的关系

为明确山东烤烟烟叶颜色特征及与显色物质的关系,采集烤后烟叶样品对烟叶颜色进行了量化分析,并探讨了烟叶颜色特征值与多酚和类胡萝卜素含量的关系.结果表明,山东不同产区烟叶颜色光谱特征存在明显的地域性差异,沂水和费县烟叶的光谱反射率较高,烟叶明度L*较高,临朐烟叶红度a*明显高于其他产区.山东不同产区烟叶多酚和类胡萝卜素含量均存在较大差异.沂水和费县烟叶的多酚含量较高,而类胡萝卜素含量较低;临朐烟叶多酚含量较低,但具有较高的类胡萝卜素含量.相关分析表明,新绿原酸、4-O-咖啡奎尼酸和绿原酸含量与颜色特征值L*呈显著或极显著正相关,而与a*呈负相关关系;叶黄素、β-胡萝卜素和类胡萝卜素含量与颜色特征值L*呈显著或极显著负相关,而与a*呈极显著正相关.     

采收成熟度对雪茄烟叶晾制过程中颜色变化的影响

为探究雪茄烟叶采收成熟度对晾制过程中颜色变化的影响，以雪茄烟品种QX103中部叶为试验材料，研究了不同烟叶成熟度（M1、M2、M3）对晾制过程中颜色表征指标、质体色素含量、含水率、丙二醛（MDA）含量、多酚氧化酶（PPO）活性、多酚含量等的影响。结果表明，晾制过程中烟叶整体变黄速率表现为M3>M2>M1，变褐速率表现为M2>M3>M1，且M2晾制后烟叶褐色较深；各处理叶绿素a、b大幅度降解，降解幅度均表现为M3>M2>M1，失水幅度表现为M2>M3>M1。各处理叶片MDA含量在晾制10 d内呈上升趋势，第10天的含量表现为M2>M3>M1；各成熟度烟叶PPO活性在晾制0～10 d上升，第10天活性表现为M2>M3>M1，处理间差异显著，在10～15d下降，M2下降幅度最大。在晾制过程中M1处理绿原酸、芸香苷、莨菪亭被氧化较少，多酚类物质积累较多。综上，在晾制过程中不同采收成熟度雪茄烟叶水分散失速率和膜脂过氧化程度存在差异，使得烟叶色素降解与多酚氧化速率不同，进一步影响雪茄烟叶颜色变化进程及晾制后烟叶颜色深浅。     

烘烤过程中烟叶颜色变化与主要化学成分的关系

以烤烟NC89中部叶为试验材料,对密集烘烤过程中烤烟烟叶亮度值L、红度值a、黄度值b、饱和度C、色相角H°、色泽比H和色差值?E的变化规律及其与主要化学成分的关系进行了研究。结果表明,烘烤过程中烟叶正面与背面L、a、b、C、H°和H值的变化趋势基本一致;其均在鲜烟叶至42℃结束时变化剧烈,42℃结束之后变化幅度趋缓。烟叶正背面色差值的变化则相对平稳,从鲜烟叶至42℃开始略有上升,在54℃稳温结束时略有下降。相关分析表明,烘烤过程中烟叶各颜色参数与淀粉、还原糖、叶绿素、类胡萝卜素、蛋白质、氨基酸和含水量之间相关性明显,大部分都达到了显著或极显著水平。通过对烟叶颜色参数与化学成分的回归分析,建立了烟叶颜色参数与主要化学成分动态变化的预测方程;除叶绿素外,烘烤过程中烤烟烟叶其他主要化学成分预测值与实测值符合程度较好,预测精度高。通过色差计量化烘烤过程中的烟叶颜色参数,从而建立烘烤过程中主要化学成分的预测模型,进行快速准确的预测,提高烘烤操作的准确性。      

上6片烟叶烘烤过程中水分与颜色及化学成分的协同变化

为优化上部烟叶烘烤技术,设置优化烘烤工艺和常规烘烤工艺2个处理,通过对烘烤过程中烟叶样品的采集分析,研究了烘烤过程中烟叶水分与颜色、内在化学成分的协同变化及烤后烟叶的品质差异。结果表明:(1)上部烟叶烘烤前期失水较难,叶片失水集中在变黄后期至定色期。(2)烘烤过程中烟叶失水与颜色及化学成分变化密切相关,随烟叶含水率由75%左右(鲜烟叶)降至60%左右,烟叶颜色由黄绿色变为浅黄色,淀粉大量降解;烟叶含水率由60%左右降至10%左右(叶片基本干燥),烟叶颜色由浅黄色变为深橘黄色,游离氨基酸含量(质量分数)明显下降。(3)烘烤过程中,烟叶含水率与颜色参数明度值(L值)和黄度值(b值)呈极显著正相关,与红度值(a值)呈极显著负相关,还原糖含量与颜色参数L值、b值和a值均呈显著正相关。(4)针对豫中产区上6片烟叶,烘烤过程中应避免变黄期不排湿、定色前期湿球温度大幅度降低而快速排湿,重视烘烤中后期的工艺参数的调控,促进烟叶内在化学成分的合理转化。     

鲜烟叶高光谱特征与颜色分析及其关系研究

  目的  明确各部位不同颜色鲜烟叶的高光谱特征及其与颜色参数的关系,为科学判定烟叶成熟度提供参考。  方法  研究了各部位烟叶颜色参数和高光谱特征的变化规律,对颜色参数和高光谱特征参数进行了相关分析和回归分析,基于高光谱特征参数建立了颜色参数回归模型,并对其进行检验。  结果  随着落黄程度的提高,颜色参数L、b、C呈不断增大的趋势,a值呈先减小后增大的趋势,H°呈不断减小的趋势;高光谱特征参数随烟叶颜色的改变呈现规律性的变化;高光谱特征参数与各颜色参数有显著或极显著相关性,基于高光谱特征参数建立的颜色参数回归模型预测效果较好。  结论  利用高光谱技术对鲜烟叶颜色参数进行分析是可行的。      

Color measurement in Lab units from RGB digital images

The superficial appearance and color of food are the first parameters of quality evaluated by consumers, and are thus critical factors for acceptance of the food item by the consumer. Although there are different color spaces, the most used of these in the measuring of color in food is the L^*a^*b^* color space due to the uniform distribution of colors, and because it is very close to human perception of color. In order to carry out a digital image analysis in food, it is necessary to know the color measure of each pixel on the surface of the food item. However, there are at present no commercial L^*a^*b^* color measures in pixels available because the existing commercial colorimeters generally measure small, non-representative areas of a few square centimeters. Given that RGB digital cameras obtain information in pixels, this article presents a computational solution that allows the obtaining of digital images in L^*a^*b^* color units for each pixel of the digital RGB image. This investigation presents five models for the RGB → L^*a^*b^* conversion and these are: linear, quadratic, gamma, direct, and neural network. Additionally, a method is suggested for estimating the parameters of the models based on a minimization of the mean absolute error between the color measurements obtained by the models, and by a commercial colorimeter for uniform and homogenous surfaces. In the evaluation of the performance of the models, the neural network model stands out with an error of only 0.93%. On the basis of the construction of these models, it is possible to find a L^*a^*b^* color measuring system that is appropriate for an accurate, exacting and detailed characterization of a food item, thus improving quality control and providing a highly useful tool for the food industry based on a color digital camera.     

新闻纸的白度、色度与不透明度

本文通过对目前新闻纸市场上新闻纸的白度、色度和不透明度的调查，结合本厂的实践提出了对新闻纸的ISO白度、CIE白度、L^＊、a^＊、b^＊值和不透明度的合理控制范围。     

Development of a computer vision system to measure the color of potato chips

The objective of this research was to design and implement an inexpensive computer vision system for measuring the color of a highly heterogeneous food material not only in shape as well in color such as potato chips in L^*a^*b^* units from RGB images. The system was composed of (i) a digital color camera for acquiring the images in a digital format, (ii) a computer for storage the images, (c) image analysis routines integrated into a software programmed in Matlab that converts the color RGB of the food image into L^*a^*b^* units. In this way the color of potato chips can be calculated in L^*a^*b^* units over representative areas and in a reproducible way. The kinetics of color changes in potato slices during frying at four temperatures was followed using the implemented computer vision system (CVS). Color values in L^*a^*b^* units were recorded at different sampling times during frying at the four oil temperatures using the total color change parameter (ΔE). Chips fried at higher temperatures get darker as expected and showed by the CVS. The implemented computer vision system can be used to study as well foods different from potato chips by selecting their proper settings for image acquisition and digital image processing.     

Effects of agricultural practices on instrumental colour,mineral content,carotenoid composition,and sensory quality of mandarin orange juice,cv. Hernandina

BACKGROUND: Frequent consumption of fruits and vegetables is associated with a lowered risk of cancer, hypertension and heart disease, due, among other factors such as modulation of gene expression and improvement of gap junctional communication, to the presence of various forms of antioxidants present in the foods as carotenoids. Otherwise, consumers demand organic products which they believe have more flavour and are of greater benefit to the environment and human health. The effects of organic farming on CIE L*a*b* colour, mineral content, carotenoid composition and sensory quality of Hernandina mandarin juices were studied. RESULTS: Organic farming of mandarin oranges resulted in juices with higher contents of minerals and carotenoids, and of better sensory quality. For instance, organic juice contained a total concentration of carotenoids of 14.4 mg L^?1 compared to 10.2 mg L^?1 of conventional juice. CONCLUSION: Mandarin orange juices can be considered as a good source of some important nutrients, such as potassium and antioxidant chemicals, e.g. β‐cryptoxanthin. Copyright © 2008 Society of Chemical Industry     

Robust colour calibration of an imaging system using a colour space transform and advanced regression modelling

A new algorithm for the conversion of device dependent RGB colour data into device independent L*a*b* colour data without introducing noticeable error has been developed. By combining a linear colour space transform and advanced multiple regression methodologies it was possible to predict L*a*b* colour data with less than 2.2 colour units of error (CIE 1976). By transforming the red, green and blue colour components into new variables that better reflect the structure of the L*a*b* colour space, a low colour calibration error was immediately achieved (ΔE(CAL) = 14.1). Application of a range of regression models on the data further reduced the colour calibration error substantially (multilinear regression ΔE(CAL) = 5.4; response surface ΔE(CAL) = 2.9; PLSR ΔE(CAL) = 2.6; LASSO regression ΔE(CAL) = 2.1). Only the PLSR models deteriorated substantially under cross validation. The algorithm is adaptable and can be easily recalibrated to any working computer vision system. The algorithm was tested on a typical working laboratory computer vision system and delivered only a very marginal loss of colour information ΔE(CAL) = 2.35. Colour features derived on this system were able to safely discriminate between three classes of ham with 100% correct classification whereas colour features measured on a conventional colourimeter were not.     

Physicochemical characterisation of quince fruits for industrial use: yield,turbidity, viscosity and colour properties of juices

In this study, were compared and characterised some of the physicochemical quality parameters as yield, turbidity and its stability of turbidity, viscosity, colour, dry matter, total soluble solid (TSS), total titratable acidity (TTA), pH parameters of quince juices accessions as well as different 11 cultivars before and after 6 months storage time at 4 and 30 °C. Quince fruits were used for the first time to prepare juices. The effect of different cultivars on juice yield was observed. The content of dry matter, TSS, TTA and turbidity value, stability of turbidity, viscosity, and colour in the analysed juices were depended not only on cultivars but also on storage conditions. Juices analysed were characterised by a significant variation in turbidity value and their stability and by a slight variation in viscosity. This information may be used by the juice industry as a starting point for producers of natural attractive juices from quince fruits.     

便携式葡萄专用可见-近红外光谱检测仪器开发与实验

基于可见-近红外光谱技术,研发低成本、便携式葡萄专用多参数检测仪器,用于满足葡萄采后品质快速、无损的检测需求。本仪器选用凹面全息光栅搭配电荷耦合器件的光谱仪作为核心器件,用于获取样品400～1 100 nm的漫反射光谱数据;选用卤素灯作为稳定可靠的光源、低OH的Y型石英光纤作为光传输的可靠媒介,并设计可调型样品池满足不同大小和品种样品的需求,基于Windows系统采用C#撰写的软件性能稳定,便于模型的更新操作。以“美人指”、“白玉霓”两个葡萄品种进行实验,指标参数包含CIE L*a*b*、可溶性固形物含量及总酚含量。结果显示,本仪器基于最小二乘-支持向量机模型对2 个品种的a*值、可溶性固形物、总酚有较好的建模效果,“美人指”各指标的模型决定系数（Rc 2 ）分别为0.91、0.94和0.90;“白玉霓”各指标的模型决定系数分别为0.96、0.99和0.95。最后,利用70 个非建模葡萄样本模型进行外部测试,结果表明“美人指”的a*值、可溶性固形物、总酚3 个指标的预测根均方误差分别为3.15、1.39 °Brix和0.24 g/kg;“白玉霓”3 个指标的预测根均方误差分别为0.78、1.56 °Brix和0.22 g/kg。结果表明,本仪器能完成对葡萄多个理化指标的建模预测,同时样品池的设计能够满足不同品种葡萄的需求。本研究为果蔬专用型近红外仪器的开发提供技术参考。     

环境温度对油菜籽储藏品质的影响

采用不同温度(15、25、35℃)对不同水分含量(6.2％、7.9％、10.6％、12.3％)的国内普通双低油菜籽进行模拟储藏,系统研究了不同温度和水分含量对油菜籽储藏期间色泽及主要品质指标的影响.结果表明:油菜籽红度值a*和游离脂肪酸(FFA)含量均随着储藏时间延长而增加,储藏温度和水分含量愈高,增加速率越大;油菜籽过氧化氢酶活动度、氮可溶性指数均随着储藏时间延长而下降,其中在35℃条件下,高水分含量的油菜籽过氧化氢酶活动度、氮可溶性指数下降迅速.油菜籽红度值a*与FFA含量、过氧化氢酶活动度、氮可溶性指数等品质指标具有显著相关性,测定其色泽可有效表征油菜籽储藏过程中的品质变化.     

油脂颜色的三种表示方法及转换关系研究

应用数字色彩传感器和微控制器设计一种油脂颜色检测实验装置,检测输出油脂颜色的三基色(红、绿、蓝)信号,即RGB值。为避免RGB模型的缺点,将油脂颜色检测值转换到与设备无关的CIE表色系统,完成由RGB值向CIE–XYZ值、CIE–L*a*b*值的转换,并采用颜色检测组件HDJD–JD02对颜色模型转化公式进行校正。结果表明,油脂颜色可以基于光学和色度学理论进行描述,并可以转换到其它颜色空间。