Quality evaluation of pickling cucumbers using hyperspectral reflectance and transmittance imaging: Part I. Development of a prototype

This article reports on the development of a hyperspectral imaging prototype for online evaluation of external and internal quality of pickling cucumbers. The prototype consisted of a two-lane round belt conveyor, two illumination sources (one for reflectance and one for transmittance), and a hyperspectral imaging unit. It had a novel feature of simultaneous imaging under reflectance mode in the visible region (400–675 nm) and transmittance mode for the red and near-infrared region (Red-NIR) (675–1000 nm). Reflectance information from the visible region was intended for evaluating the external characteristics of cucumbers such as skin color, whereas transmittance information from Red-NIR was used for internal defect detection (i.e., hollow center). Additional features of the prototype included simultaneous acquisition of reflectance and transmittance from calibration references that were installed in the system, to provide real-time, continuous corrections of individual hyperspectral images from each sample. Methods and algorithms were developed of estimating cucumber fruit size and correcting the effect of fruit size on transmittance measurements. The system was calibrated and evaluated for detecting the color, size, and internal defect of pickling cucumbers.     

Fluence (UV dose) distribution assessment of UV-C light at 254 nm on food surfaces using radiochromic film dosimetry integrated with image processing and convolutional neural network (CNN)

Uniform Fluence (UV Dose) distribution on food surfaces is essential for an effective UV process design. In this study, the use of radiochromic films (RCFs) with a computer vision system (CVS) integrating image processing and Convolutional Neural Network (CNN) is proposed as an alternative method to assess Fluence distribution of UV-C light at 254 nm on food surfaces. The color difference of RCFs exposed to different UV irradiance and exposure times was correlated with Fluence. The validity of the developed methodology was proved by applying it to the surface of apple fruits of different shapes and sizes. A linear relationship was found between the color difference of RCF and Fluence. The maximum Fluence to be determined using RCFs was ∼60 mJ/cm². The color of the films after UV irradiation remained stable for up to 15 days in darkness when stored at room and refrigeration temperatures. The results showed that RCF can be used as an alternative UV dosimeter.     

Possibilities for predicting taste and tenderness of broiled beef steaks using an optical-electromechanical probe

A prototype beef-quality probe was tested on 47 strip-loin steaks evaluated by a sensory panel. The probe responded to the reflectance or back-scatter of initially polarized light from 400 to 800 nm, UV fluorescence of connective tissue, and electromechanical resistance to needle penetration. All three indicators contributed to predictions (p < 0.01) of tenderness (r = 0.58 for initial tenderness after 3 days aging, r = 0.57 for sustained tenderness at 3 days, r = 0.42 for initial tenderness at 21 days, and r = 0.58 for sustained tenderness at 21 days) and taste (r = 0.59 for flavor intensity at 3 days, r = 0.41 for beef flavor at 3 days, and r = 0.41 for flavor intensity at 21 days). The reflectance of initially polarized light from 440 to 600 nm appeared to contain a relatively high content of useful information, but further improvements to the prototype are required to obtain more reliable predictions for industrial use.     

颜色测量结果的不确定度评定方法

 为了降低印染、印刷行业中因颜色测量偏差而造成的产品质量问题,更好控制产品的质量,需对颜色测量结果质量进行评定。在对测量不确定度评定方法进行分析的基础上,结合颜色测量的特点对测量结果不确定度进行评定。根据ISO不确定度评定标准,首先基于不确定度的来源和不同光谱反射率间相关系数对光谱反射率不确定度计算方法进行分析,再基于光谱反射率不确定度计算色度值不确定度。最后用实例说明颜色测量结果的不确定度评定方法是可行的,为今后进一步的研究奠定理论基础。     

货架陈列期间光照处理对鲜切青椒品质的影响

为研究白光、红光、蓝光、绿光光照以及避光处理对鲜切青椒（Capsicum annuum L.）品质的影响,将鲜切青椒在货架陈列期用不同光照处理,贮藏5 d后,比较鲜切青椒质量损失率、颜色、相对电导率、丙二醛含量和风味的差异。结果发现：在各光照处理组中,绿光处理组鲜切青椒的质量损失率最低,为3.75%,且该处理对可溶性固形物质量分数、果实水渍化损伤程度、果实颜色变化的影响均较小,与新鲜样品相比,其色差仅为3.22,显著低于白光处理组（P＜0.05）;并且与白光处理组相比,绿光处理对鲜切青椒的风味没有显著影响（P＞0.05）。因此,绿光处理有助于维持鲜切青椒在货架陈列期的品质。     

Discoloration of Fresh Pork as Related to Muscle and Display Conditions

Pale, soft, exudative (PSE), normal, and dark, firm, dry (DFD) pork was held 7 days at 4°C under light or dark then color was evaluated instrumentally and visually. Change in reflectance (R630-R580) was used to estimate color changes due to oxymyoglobin. PSE pork was lighter (high L*) than normal and DFD pork, but did not change over time. An increase in a* and R630-R580 occurred the first day for normal and DFD, but not for PSE samples. A subsequent increase in hue angle and decrease in R630-R580 (loss of redness) occurred in PSE and normal, but not in DFD samples. Changes in hue angle and R630-R580 were more rapid in PSE than in normal samples. Light exposure accelerated all changes except L*. Visual redness inversely correlated with L* value.     

Cholesterol photosensitised oxidation of horse meat slices stored under different packaging films

The effect of the type of packaging film (transparent vs. light-protecting red film) was evaluated on the formation of cholesterol oxidation products (COPs) in refrigerated horse meat slices stored in retail conditions under light exposure for 8 h. In meat wrapped with a transparent film, COPs increased from 233 (control) to 317 μg/g of fat, whereas the red film delayed cholesterol oxidation and offered protection against COPs formation, since COPs decreased from 173 (control) to 139 μg/g of fat after 8 h of light exposure. In addition, light opened the epoxy ring and led to the formation of triol, which was actually absent at T_0. A proper packaging film may represent a useful strategy to retard oxidative degradation in a light-sensitive, high pigment- and fat-containing food, such as horse meat.     

背衬板对薄织物耐光色牢度评级结果的影响

针对GB/T 8427—2019中白纸卡的要求,对比轻薄易透织物耐光色牢度直接评级和背置三级标准棉贴衬评级结果的差异,研究了背衬材料在耐光曝晒过程中泛黄现象对轻薄易透织物耐光色牢度评级结果的影响.提出了一种既可采用非标准背衬材料,又可以消除曝晒过程中泛黄而引入评级误差的简易办法,有利于同行对于耐光色牢度标准中白纸卡要求...     

Short communication: Influence of pulsed light treatment on the quality and sensory characteristics of Cheddar cheese

The objective of this study was to examine the effect of pulsed light (PL) treatment on the color, oxidative stability, and onset of molding of Cheddar cheese. Slices of sharp white Cheddar cheese of 2.5 × 5 cm were treated on one side with PL doses from 1.02 to 12.29 J/cm², sealed in polyethylene bags, and stored at 6°C for up to 1 mo. Peroxide value, color parameters, and the onset of molding were evaluated. No significant changes in color or peroxide value were observed for PL-treated samples compared with the untreated controls. Pulsed light was able to significantly delay surface molding during refrigerated storage, with a PL dose of 9.22 J/cm² delaying the onset of molding by 7 d. The effect of PL on the taste, appearance, and acceptability of Cheddar cheese slices treated with a PL dose of 9.22 J/cm² on each side was assessed. In triangle tests, 60 untrained panelists were unable to detect significant differences between the control and PL-treated samples, although PL had a significant effect on overall liking, flavor, and appearance. These findings suggest that although PL can be effective for surface decontamination of cheese, it may have some detrimental effects on sensory properties.     

Evaluation of dosimeter tubes for monitoring phosphine fumigations

Within integrated pest management options, fumigation of stored products is one method to help control post-harvest insect infestations in our food and agricultural products. Fumigant gas concentration monitoring is important to confirm that the treatment was adequate to achieve the desired insect control, but monitoring can be relatively expensive and labor intensive. This study evaluated how accurately dosimeter tubes could monitor phosphine fumigation treatments. The dosimeter tube is designed to continuously react with phosphine gas during the fumigation period and yields a measurement in terms of concentration 1 time product or CT, which can be interpreted as cumulative exposure. Two models of dosimeter tubes were evaluated (high range and low range). The reference method for these trials were wireless phosphine monitoring sensors, which recorded gas concentrations at hourly intervals during an exposure, and from this a CT product was also calculated. Model LPG-1, high-range dosimeter tube, measured within ± 25% of the phosphine monitoring sensors for CT dosages less the 70,000 ppm1hr. Model LPG-2, low-range tube, tended to significantly over-estimate phosphine CT dosage by 50%–100% of the phosphine monitoring sensor references. Secondly, bioassays of fumigant efficacy were performed using susceptible and resistant adult Rhyzopertha dominica (F.) (Coleoptera: Bostrichidae), lesser grain borers, and Tribolium castaneum (Herbst) (Coleoptera: Tenebrionidae), red flour beetle, for estimating insect control at the varied fumigation CT treatments. For the susceptible strains, CT dosages ∼5000 ppm1hr controlled both species. However, the insect control varied from 60% to 100% for resistant adults at CT dosages of ∼20,000 ppm1hr. The dosimeter tubes function in these ranges of dosages where each insect species are controlled and the dosimeter tube model LPG-1 provides reasonable estimates of the fumigation dosage for a given treatment level.     

Prediction of Food Emulsion Color Using Light Scattering Theory

A theoretical model was developed to predict spectral reflectance and color of emulsions from droplet (radius and concentration) and dye (absorption spectra and concentration) characteristics. The Rayleigh-Gans-Debye theory of light scattering was used to calculate the scattering cross-section, absorption cross-section and asymmetry factor of droplets. These values were used to calculate spectral reflectance of an emulsion based on Kubelka-Munk theory. The tristimulus coordinates (L, a, b) of an emulsion were calculated from its spectral reflectance using color matching functions. Predictions were in good agreement with experimental measurements on oil-in-water emulsions containing a red food dye. The theory may be useful for optimization of emulsion appearance.     

基于神经网络的籽棉颜色分级检测

为解决籽棉颜色分级问题,构造了一个基于L^*a^*b^*颜色空间的色度检测仪,主要由颜色传感器、光源及外围电路构成。针对用于籽棉颜色等级检测2个关键指标(反射率、黄度)输出不稳定问题,采用了4层BP神经网络和5块标准色板进行反复训练,使得校准后的反射率的变异系数小于0.21%,黄度的变异系数小于1.13%。在籽棉颜色等级检测实验中,制作了覆盖12个颜色等级的480个测试样。经过反复实验发现,使用该色度检测仪对1个测试样品,需要均匀分布10个测量点结果的平均值,才能得到稳定的色度测量值。最后,采用神经网络方法,对480个籽棉试样数据进行分析,其中:80%用于训练;20%用于识别。实验结果表明,对12个颜色等级的480个样品进行测试,得到的检测准确率都超过了90%。     

腈纶纺丝生产线中的染色

详细介绍腈纶纺丝生产线中染色的原理，优点，实施方法和使整束丝内外部都能均匀染色等工程问题的解决方法。通过纺丝线中染色也可制造光致变色腈纶。     

货架陈列期间光照处理对鲜切芹菜叶品质的影响

评价货架陈列期间光照处理对鲜切芹菜叶品质的影响。研究在4℃货架陈列期间,使用白光、红光、绿光和蓝光对鲜切芹菜叶进行光照处理5 d,以白光处理组作为CK组,比较样品失重率、颜色、叶绿素含量、相对电导率、丙二醛含量、氧自由基吸收能力(Oxygen radical absorbance capacity,ORAC)、风味和感官评分。结果发现,绿光(该光源主要发射峰位于510~530 nm,光谱纯度为100%,强度为(2977±181.5) Lux)处理组鲜切芹菜叶的失重率(4.68%)比CK处理组降低了28.4%,并降低叶片黄化和萎蔫程度;绿光处理使鲜切芹菜叶的氧自由基吸收能力值达到485 μmol/g,比CK处理组提高了11.5%;而蓝光处理组出现叶片黄化现象,红光处理组样品风味发生显著性改变。因此,绿光处理更有利于保持鲜切芹菜叶原有的颜色、香气和感官品质。     

Factors Affecting Light-Induced Pink Discoloration of Annatto-Colored Cheese

The effects of light type, exposure and intensity, storage temperature, pH, fat content, and age and source of colorant were evaluated on stability of annatto colorants in cheese. Exposure to cool white fluorescent lighting resulted in a decrease in Hunter b values and hue throughout storage. Decreased temperature reduced the loss of a and b values after 2 days of light exposure. As time of exposure increased, reduction of a and b also increased. As pH changed from 5.4 to 4.8, b values were reduced at a faster rate than a values resulting in an intense pink color. Commercial cheese colorants extracted from annatto seeds were variable in color stability.     

CHARACTERIZATION OF THE DIFFERENT STATES OF MYOGLOBIN IN PORK USING COLOR PARAMETERS AND REFLECTANCE RATIOS

Because color is becoming more important to the food industry, color studies are being conducted to improve the control of both raw materials and processes. Several studies have pointed to the importance of the different states of myoglobin in determining the color changes which take place during processing. The aim of this study was to characterize the color parameters (CIE LAB coordinates, reflectance spectrum and reflectance ratios) of the three myoglobin forms (deoxymyoglobin, oxymyoglobin and metmyoglobin) in pork Subscapularis muscle. The deoxymyoglobin present in fresh pork lean meat was converted into the pure states, and color parameters (lightness, redness, yellowness, hue, chroma and a*/b* ratio), reflectance spectrum (400–700 nm) and reflectance ratios (R560/R500, R650/R570, R630/R580 and R630-R580) were obtained. All the color parameters and reflectance ratios (except redness values) varied according to the state of the myoglobin.     

家用洗涤剂对洗涤织物的荧光作用

采用市售的多种洗涤剂对棉、真丝织物进行洗涤,分别考察了洗涤剂种类、质量浓度、洗涤时间和温度对织物荧光效果的影响。结果表明:洗涤剂对白色、浅色织物的荧光作用较深色面料显著,洗涤织物的荧光白度随洗涤剂质量浓度的增加而提高,洗涤时间和洗涤温度对织物荧光作用的影响因洗涤剂种类不同而存在明显差异。     

Color stability of heat-treated wood during artificial weathering

The color change of wood after exposure to UV light may produce aesthetical damages. The stability of the color to light exposure is an important issue. This study describes experiments of testing the color stability of heat-treated wood samples. Heat treatment was done at 240°C during 2 hours, under nitrogen. Heat-treated samples of ash, beech, maritime pine and poplar heartwood were exposed to UV-light (QUV equipped with fluorescent lamps UVA-340) during 835 hours. Color measurements during accelerated weathering were made at intervals throughout the test period. The results are presented in ΔE and L* a* b* coordinates according to the CIELab system. The experiments show that the color stability for heat-treated wood is better during the 835 hours of exposure when compared to untreated wood. The properties of heat treated wood (lignin modifications, and monomers of phenolic compounds) are probably involved in the retified wood resistance against UV light under experimental conditions.     

Effect of electron beam irradiation on color and microbial bioburden of red paprika

The effect of irradiation with electron beams on the microbiological quality and color properties of red paprika was examined. The irradiation doses ranged from 0 to 12.5 kGy. The counts performed were total mesophilic aerobic microorganisms, Enterobacteriaceae, coliforms, sulfite-reducing clostridia, molds, and yeasts. It was concluded that molds, yeasts, and sulfite-reducing clostridia were the most resistant species, although a 10-kGy dose of irradiation leads to optimum sanitation. Extractable color and apparent color were analyzed to appraise the incidence of the irradiation treatments in the color properties of red paprika. Extractable color was determined according to the American Spice Trade Association method, and apparent color was analyzed by reflectance using the CIELab color space. Data showed no significant differences between the color properties of irradiated and nonirradiated samples. Irradiation was a suitable procedure to minimize the bioburden of red paprika with small modifications of its color properties.     

Influence of exposure to light on the sensorial quality of minimally processed cauliflower

ABSTRACT:  The impact of lighting on minimally processed cauliflower packaged in 4 different film types (PVC and 3 P-Plus) has been measured and quantified. The effect on the sensorial quality of storage at 4 °C in darkness and partial or continuous lighting was evaluated. The gas concentrations in the packages and the weight losses were also determined. Atmosphere composition inside the packages depended on both the permeability of the film used for the packaging and exposure to light. Samples stored with lighting maintained the gaseous exchange between plant tissue and the atmosphere inside the packages for longer periods than in samples kept in darkness. This prompted a greater loss of water vapor as well as the development of atmospheres with low levels of O₂ and high levels of CO₂ in the samples packed with less permeable films. The most important aspect in sensory evaluation was color. In instrumental color evaluation, coordinates h * and L * were the main means for estimating color evolution. The presence of light accelerated browning in the cut zones. The development of abnormal coloring in these areas marked the end of shelf life for minimally processed cauliflower. Among the sensory attributes studied, color was the most affected by exposure to light. Samples packed in P-Plus 120 film displayed the lowest level of color deterioration in the cut zones. However, under lit conditions, the low permeability of this film caused atmospheres with very low O₂ contents and high CO₂ contents. These atmospheres produced a loss of texture and the development of off-odors.