The measurement of colour has been frequently used as an alternative to chemical analysis in a wide range of applications. Colorimetry and spectrophotometry are the reference techniques nowadays to ...measure colour. Practical problems arise, however, when granular, powdery, rough, curved or non-regular surfaces are processed. A standard digital camera, in combination with image analysis, can be used as an inexpensive, portable, non-destructive and fast analytical tool to measure colour but, surprisingly, this approach has not been fully exploited up to date. In this work, we have used this technique to measure tomato colour at different ripening stages. Spectrophotometric analysis of the extracts of the tomatoes allowed us to record the characteristic spectrum of each sample and correlate them with the chromaticity parameters by non-linear regression analysis of the whole data set. The resulting mathematical model showed a high power to discriminate between tomatoes, and was further used to produce a relative scale from zero to ten that enabled us to sort naturally matured tomatoes according to their ripening stage. In addition, the proposed model also allowed a fast estimation of the lycopene content in the samples, avoiding long and tedious extraction procedures, with a significant saving of time and reagents.
•A standard digital camera and image analysis as tool to measure colour is proposed.•The methodology has been applied on tomatoes to estimate their ripening stage.•The resulting mathematical model showed a high power to discern between tomatoes.•The proposed methodology may also be used to estimate the lycopene content.
•Two instrumental techniques viz. computer vision system (CVS) and colour spectrophotometer were evaluated for colour measurement of mozzarella cheese.•Performance of CCD and CMOS based cameras were ...evaluated for colour measurement application using computer vision technology.•A novel validation step is proposed for characterization of different image acquisition devices.•Developed CVS has the potential to be used in the cheese industry as a rapid and inexpensive colour measurement tool.
The colour of food is one of the most important selection criteria affecting purchasing decision of a consumer. Conventionally, colour is measured using colorimeters and colour spectrophotometer. In recent times, computer vision technology has emerged as a robust technique and can be implemented as an alternative to conventional colour measurement methods. A cost-effective computer vision system was developed for measuring the colour of mozzarella cheese with provision to mount different cameras. Various CCD and CMOS based digital cameras were calibrated and evaluated for image acquisition of cheese samples. An additional validation step was introduced to characterize different image acquisition devices on the basis of Root Mean Square Deviation (RMSD) and Mean Normalized Error (MNE). The colour measurement algorithm extracts RGB values from the sample image and coverts into CIE L*a*b* units. The conversion between two colour spaces was done employing standard equations. The colour of mozzarella cheese samples was measured in the CIE L*a*b* color space with the computer vision system (CVS) and commercial colour spectrophotometer. Both the systems yielded equivalent results and developed CVS can be used to study colorimetric quality parameters of mozzarella cheese.
Research background. This study fulfils a need for investigation of a quality profile of
snail fillets. Edible snails are a famous food product consumed worldwide and treated as delicacy. Nutritional ...value, colour and textural properties, such as hardness, are critical factors that impact consumer acceptance of the product. Hardness of snail meat is affected by its native original microstructure.
Experimental approach. Fresh snails of the farmed species Cornu aspersum maximum,
wild and farmed Cornu aspersum aspersum and wild Helix lucorum were used in order to investigate the qualitative profile of snail meat. Proximate composition, hardness and colour measurements were conducted on fillets of all species. The histological structure of the fillets of Cornu aspersum maximum was examined.
Results and conclusions. Quality parameters of snail fillets were studied. A novel method of hardness analysis was proposed where the cylindrical part of snail fillets from the mid-posterior region with specific geometry 6 mm diameter and 6 mm height was used. The suitability of the mid-posterior region was enhanced by the uniform structure confirmed by the histological analysis. Helix lucorum snail fillet had the highest energy content and the highest hardness but the lowest carbohydrate content. The species Cornu aspersum maximum was evaluated with the highest values of a* (redness), b* (yellowness) and C* (chroma) compared to other species. Parameter L* (lightness) of wild snail fillets was lower than of the farmed ones due to age, diet, farming or environmental conditions, but it could also be related to snail carbohydrate content.
Novelty and scientific contribution. This study yielded notable results on qualitative characteristics of snail fillets as food and important information is given on its meat properties. Furthermore, a novel methodology of hardness is provided in order to minimize natural, breeding and environmental influences. Finally, the research outcomes could lead to proper handling methods for further fabrication of snail meat.
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•Colour and crystallinity changes in heat-treated teeth can be measured using spectrophotometric and XRD analyses.•Both analyses provide numerical data for colour and hydroxyapatite ...crystallite size.•Results demonstrate crystal size and yellowness were significantly affected by the rise of heating temperature.•The integration of both analyses can generate a reliable and accurate estimation of temperature exposure for burned dental remains.
Heat alters colour and crystallinity of teeth by destruction of the organic content and inducing hydroxyapatite crystal growth. The colour and crystallite changes can be quantified using spectrophotometric and x-ray diffraction analyses, however these analyses are not commonly used in combination to evaluate burned dental remains. In this study, thirty-nine teeth were incinerated at 300–1000 °C for 15 and 30 min and then measured using a spectrophotometer and an x-ray diffractometer. Response variables used were lightness, L*, and chromaticity a* and b* and luminance (whiteness and yellowness) for colour, and crystal size for crystallinity. Statistical analysis to determine the attribution of these variables revealed yellowness and crystal size were significantly affected by temperature (p < 0.05), whilst duration of heat-exposure showed no significant effect. This study suggests the inclusion of both spectrophotometric and x-ray diffraction in investigating thermal-heated teeth is useful to accurately estimate the temperature teeth are exposed to.
•Faded effects on denim produced using a commercial laser cutting/engraving system.•The process is more precise than established fading methods and is chemical free.•Correct implementation of laser ...treatment ensures retention of fabric properties.•Significant loss of blue colour is attainable with minimal fibre degradation.•The laser process is reproducible and has the potential to produce complex designs.
Denim garments are particularly popular with the younger population of adults. Distressed or worn out effects have been and will continue to be popular with this market sector. These faded or worn effects have been achieved using a range of physical, chemical and mechanical finishes. Both wet and dry finishing of denim fabrics and garments pose severe environmental and health risks. Recently, environmentally beneficial decolourisation/ablation methods for denim fabrics have been investigated. Such methods have included plasma, laser, and ozone treatments. Researchers in this field have highlighted the potential of CO2 laser treatment of 100% cotton denim, however the textile performance post-treatment has not been properly investigated. In this study, light, medium and heavy weight indigo dyed 100% cotton denim fabrics were exposed to a CO2 laser at a range of power and intensity levels. Colour change was investigated using a Spectrophotometer, morphological structural analysis was carried using Scanning Electron Microscopy, and attenuated total reflectance Fourier transform Infrared spectroscopy (ATR-FTIR) was used to monitor the loss of indigo dye and degradation of the cellulose fibres. The thermal-oxidative degradation behaviour of fabrics was also studied using differential scanning calorimetry to obtain oxidation onset temperature. In addition, several fabric performance assessments were carried to evaluate tensile strength, colour fastness, air permeability and thickness. Findings reveal that the grayscale rating, which is the tone density and hence laser power affected the colour change and as the grayscale increased, the colour fading was higher and affected the fabric performance across all fabric weights. Based on this, the research recommends an optimum set of laser processing parameters to produce stressed or faded denim effects without compromising the fabric performance. This research demonstrates that faded effects on denim can be produced with low environmental and health risks.
Objectives. To review current knowledge with respect to tooth colour and its measurement.
Methods. ‘Medline’ database for the period 1966 to the present day and ‘ISI Web of Science’ database for the ...period 1974 to the present day were searched electronically with key words tooth, teeth, colour and color.
Conclusions. The colour and appearance of teeth is a complex phenomenon, with many factors such as lighting conditions, translucency, opacity, light scattering, gloss and the human eye and brain influencing the overall perception of tooth colour. The measurement of tooth colour is possible via a number of methods including visual assessment with shade guides, spectrophotometry, colourimetry and computer analysis of digital images. These methods have successfully been used to measure longitudinal tooth colour changes when the dentition has undergone tooth whitening procedures.
Quince
(Cydonia oblonga
Miller) is a widely consumed, safe, and low-cost natural source of different classes of interesting metabolites. Phenolic compounds in natural foods (especially fruits and ...vegetables) have application as preventive or therapeutic agents in the treatment of diseases caused by free radicals. This study focused on total phenolic content, DPPH and ABTS activities as antioxidant properties, and polyphenol oxidase (PPO) inhibitory activity of the total phenolic compounds extracted from quince leaf, peel, and seed. Quince leaf and peel extracts showed higher ABTS and DPPH activity than quince seed extract. Additionally, all quince extracts inhibited PPO, with IC
50
values of 36.47 ± 8.28 µg/ml (leaf extract), 173.25 ± 5.69 µg/ml (peel extract), and 386.75 ± 9.27 µg/ml (seed extract). Moreover, the effects of extracts on enzymatic browning in apple were examined by measuring the color parameters.
Old textiles represent important samples of the mobile cultural heritage, having implications on the social and spirituallife of each population. In order to keep them in the best condition, it is ...necessary to implement methods to preventdamages, but also to rehabilitate and clean the already affected fabrics. In the case of textiles that need to be treated,a fundamental thing is the unaltered preservation of the initial characteristics of the materials, even after theinterventions. The aim of our study is to test the feasibility of a non-invasive alternative to usual chemicals for cleaningtextiles; Chitosan’s antimicrobial and cleaning effects on a pair of Romanian traditional cotton trousers, from Maramuresarea was analyzed. A few images were taken from SEM of untreated and treated fabric with Chitosan solution usingdifferent magnifications, in order to check the changes on the fabric surface. The purpose was to observe if there aresome color changes after Chitosan treatment, so the CIELAB color values (L, a, b) of untreated and treated sampleswere analyzed. The analysis of the treated samples revealed strong antimicrobial effects of Chitosan
This study aimed to investigate the variability of skin colour measurements for two kinds of extensively used instruments, telespectroradiometers (TSR) and spectrophotometers. A Konica Minolta CM700d ...spectrophotometer and a PhotoResearch PR650 telespectroradiometer were used to measure the forehead and the cheekbone of 11 subjects. The variability was evaluated using different measurement parameters including measurement aperture size and pressure on the facial locations for the spectrophotometer, and measurement distance for the telespectroradiometer. The mean colour difference from the mean was used to define the short‐term repeatability; the CIELAB colour difference and colour appearance changes in each perceptual CIELAB attribute between each of two instrument settings were used to evaluate the inter‐instrument agreement. The results show that, for the TSR, different measurement distances have identical repeatability but the colour shifts were significant; for the spectrophotometer, the large aperture size of the target masks gave the most repeatable results and the aperture size had more influence on the colour shifts than the measurement pressure. In addition, to investigate the effect of ethnicity and body location on measurement variability, skin colours from additional 151 subjects were measured. The differences between the measurements for different body locations were, in general, larger than the instrument repeatability and the inter‐instrument agreement.
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