CIE Color Parameters Research Articles

Printability and Thermophysical Properties of Three-Dimensional-Printed Food Based on "Cochayuyo" Durvillaea antarctica Seaweed Flour.

This research assessed the feasibility of adding Cochayuyo seaweed flour (at 30, 50, and 70% levels) to rice flour-based paste to improve its 3D printing quality. The paste's rheological properties, printing quality, texture profile, thermal properties, and color of 3D-printed foods were explored. Results showed that pastes with Cochayuyo addition exhibited shear-thinning behavior, and viscosity increased with increased Cochayuyo concentration. Viscoelastic properties and a Texture Profile Analysis (TPA) revealed that Cochayuyo improved mechanical strength and made the paste easier to flow, improving printed food's extrudability, fidelity, and shape retention, which was better observed in RC50 and RC70 printed at 15 mm s-1. A differential scanning calorimetry (DSC) analysis showed a partial substitution of rice flour for Cochayuyo flour in the formulation. This increased the onset and melting peak temperatures and reduced the enthalpy of fusion. CIE color parameters a*, b*, and L* showed that Cochayuyo addition increased the color to yellow and red; however, lightness was considerably reduced. Therefore, Cochayuyo flour could have the potential to be used for the manufacture improvement of 3D-printed food with better rheological, mechanical, thermal, printing quality, and nutritional properties, making possible the exploitation of the native Cochayuyo seaweed, which is highly available in Chile.

Assessment of changes in enamel colour following fixed orthodontic therapy using an advanced spectrophotometer: An in vivo study.

Any manipulation of the surface of natural teeth may result in a variation of their colour. The fixed orthodontic treatment (FOT) is one such procedure which alters the enamel surface during the procedure. To clinically evaluate the colour changes in teeth associated with comprehensive FOT (to compare the changes in test and control groups) and to determine the relationship of age and gender on enamel colour due to FOT by using an advanced spectrophotometer. The selection of sixty patients for the study was done randomly and among these thirty patients who underwent the FOT as the case group, the other thirty patients who did not need FOT, were the control group. The recordings of spectrophotometric data were done in a standardized manner for all patients in the labial circular region of every anterior tooth, following debonding and cleaning operations, and before bracket bonding. The Commission Internationale de l'Eclairage's L*, a*, and b* (lightness, red/green, and blue/yellow) tooth-type characteristics were used to measure color, and the associated color differences (DE) between the groups were computed. One-way ANOVA (a < 0.05) and the paired t-test were used to evaluate any changes in these color characteristics. Fixed orthodontic treatment is associated with changes in colour parameters. L* values decreased (P< 0.001), while a* and b* values increased (P< 0.001) at the end of treatment. All measured tooth types showed significant colour change (DE); their mean differences ranged from 1.64 to 2.96 DE units. Fixed orthodontics can change the natural colour of teeth. The CIE colour parameters L*, a*, and b* of natural teeth showed statistically significant differences after debonding the orthodontic appliances. The L* values decreased making the teeth look darker. The adolescent and male patients had more tooth colour changes than the adult and female groups.

Assessment of In Vitro Antioxidant Capacity of Ginseng Extract and Its Effect on Inhibiting Lipid Oxidation and Physicochemical Properties of Cooked Ground Beef During Refrigerated Storage.

Ginseng is a medicinal plant that has anti-inflammatory, antidiabetic, anticancer, antiobesity, cardioprotective, antioxidant and antimicrobial properties. However, previous reports lack information on the effects of ginseng extract on the shelf life and quality characteristics of muscle foods. Thus, it is essential to determine the effects of ginseng extract on the meat model system to gain valuable insights to improve the shelf life and quality of muscle foods. After determining the in vitro antioxidant activity of ginseng extract, the antioxidant effect of ginseng extract on cooked ground beef was investigated. In vitro antioxidant activity was determined using Fe(III) reducing antioxidant power (FRAP), 1,1-diphenyl-2-picrylhydrazyl (DPPH) scavenging and total phenolic content (TPC) analyses, while lipid oxidation, chemical, microbiological and textural changes were determined during 30 days of storage. Cooking loss, proximate composition and textural features were measured after thermal processing. The pH, CIE colour parameters, thiobarbituric acid reactive substances (TBARS), lipid hydroperoxide (LPO), total aerobic mesophilic bacteria, total coliform bacteria, yeast and mould counts were determined during refrigerated storage. The mean values for FRAP expressed as Fe(II) equivalents ((4.7±0.2) mmol/g), DPPH (IC50=(12.11±0.09) mg/mL) and TPC expressed as gallic acid equivalents ((146.0±2.4) mg/g) showed a potential antioxidant capacity of ginseng extract. The addition of ginseng extract increased the cooking loss (p<0.05), but it did not affect the proximate composition of ground beef. It also caused a decrease in pH (p<0.05). Ground beef samples containing 1 % or more ginseng extract had lower TBARS values than control (p<0.05). In addition, LPO values of ground beef with ginseng extract were lower than the control after 30 days of storage (p<0.05). Total aerobic mesophilic bacteria, total coliform bacteria, yeast and mould were not found in any of the groups, except in the control, which had 3.35 log CFU/g total aerobic mesophilic bacteria at the end of storage. The results show that ginseng extract has an important activity in controlling lipid oxidation and can be used in the meat industry to extend shelf life and microbial stability.

Estimation of Andrographolide and Antioxidant Activities in Andrographis peniculata Commercial Products by Color Parameters

Andrographis paniculata (Burm.f.) Wall.ex Nees is a standing out medicinal herb. It contains a large quantity of andrographolide and wildly used a traditional herb in many countries. Andrographolide is found in all part of the plant. However, those part are different in color, active compound content and antioxidant activity. Even though, there are several methods to determine andrographolide and antioxidant. They are chemical involved, complicated and time consuming. Therefore, the objective of this study was to develop estimation method of andrograhpholide content and antioxidant activities by CIE color parameters. The result showed that range of CIE color parameters of andrographolide sample were broad with range from light greyish yellow-green to greyish dark green. Antioxidant activity was barely correlated with colors. However, andrographolide content showed moderate correlation with colors. Dark green andrographis herb contain higher andrographolide than light greyish yellow-green one. Furthermore, andrographolide content could be numerical estimated by CIELab and CIELCh color parameters. The developed estimating method were easy, rapid and no chemical involved. HIGHLIGHTS Andrographolide content showed moderate correlation with colors Darker and greener andrographis herb was assumed that contain higher amount of andrographolide Andrographolide content could be numerical estimated by CIELab and CIELCh color parameters The estimating model were easy, rapid and no chemical involved GRAPHICAL ABSTRACT

Changes in Pomological and Physical Parameters in Rosehips during Ripening

Rosehips of various Rosa spp. are well known for having human health-promoting compounds like mineral nutrients, vitamins, fatty acids, and phenolic compounds. However, little is known about rosehip characteristics which describe the fruit quality and may indicate appropriate harvest times. Our study evaluated the pomological (width, length, and weight of fruits, flesh weight, and seed weight), texture, and CIE colour parameters (L*, a*, and b*), chroma (C), and hue angle (h°) of rosehip fruits of Rosa canina, Rosa rugosa, and genotypes of Rosa rugosa 'Rubra' and 'Alba', harvested at five ripening stages (I-V). The main results revealed that genotype and ripening stage significantly affected parameters. The significantly longest (R. canina) and widest fruits (R. Rugosa) were measured at ripening stage V. Genotypes of R. rugosa 'Rubra' and 'Alba' had significantly higher fruit and flesh weights at ripening stage V. Rosehips of all investigated genotypes expressed darkness (lower L*) during ripening, and had the highest hue angle h° values at ripening stage I while the lowest was at stage V. The significantly lowest skin elasticity of rosehips was found at stage V. However, R. canina was distinguished by the highest fruit skin elasticity and strength. As our results show, the desired pomological, colour, and texture features of various species and cultivars rosehips can be optimised according to the harvest time.

Coordinated water stabilizes indigo-sepiolite hybrid pigments: Evidence from acid modification

Sepiolite can form stable hybrid pigments by immobilizing organic dyes in its microporous structure. Previous investigations demonstrated that the micropores and coordinated water might be responsible for the exceptional color and stability of indigo-sepiolite hybrid pigments. This work reveals the roles of coordinated water in forming hybrid pigments by acid modification. Raw sepiolite was modified by nitric acid at different conditions before use. Then a series of indigo-sepiolite pigments were prepared by indigo and acid-modified sepiolite. Their microstructures were characterized and analyzed by X-ray diffraction, Fourier transform infrared, transmission electron microscopy, and N2 adsorption-desorption. The color properties of hybrid pigments were evaluated by reflectance spectra and CIE color parameters. Investigations into the chemical stability of pigments were conducted using concentrated HNO3 and dimethyl sulfoxide. In addition, the photostability of pigments exposed to simulated 30-year illumination in a typical museum was studied. Acid modification of sepiolite contributed to a larger specific surface area and pore volume. However, acid modification resulted in worse color properties and stability due to the removal of coordinated water bonded with octahedral Mg2+. These findings confirmed that coordinated water molecules were the key to stabilizing indigo-sepiolite hybrid pigments by forming hydrogen bonds.

Antibacterial Effect of Polymethyl Methacrylate Resin Base Containing TiO2 Nanoparticles

Restorations in dentistry must reproduce the aspect of the patient’s natural teeth and require non-toxicity, biocompatibility, and good mechanical properties in order to last longer. Restorations are permanently in contact with microbes that can adhere to and form biofilms. The purpose of this study was to determine the adhesion extent of Streptococcus mutans to polymethyl methacrylate (PMMA) resin base containing TiO2 nanoparticles. To understand the adhesion of Streptococcus mutans on the modified resin-based surfaces, the following surface properties were measured: the roughness, contact angle, zeta potential and CIE color parameters. Evaluation of tensile stress performance in TiO2 modified PMMA showed that the maximum tensile stress of the modified PMMA resin decreases with an increasing amount of TiO2 nanoparticles. The increasing amount of TiO2 decreases the roughness and causes contact angles in the border between hydrophilic and hydrophobic surfaces. All the studied surfaces are negatively charged and added TiO2 tends to increase the zeta potential. The addition of TiO2 nanoparticles increases the lightness and decreases the intensity of the red and yellow color. The increasing addition of TiO2 nanoparticles into PMMA increases the morphological change of bacterial cells.

Chromaticism differentiations: How variegated homogeneous stones used in buildings can gain diversified aesthetic appeal

This manuscript presents the results of a research about the change in colour of five different dimension stones, which are worldwide used for cladding and paving, whenever undergoing different surface processings. Substantial changes of the surface features, such as roughness and gloss were measured and correlated with CIE colour parameters. A spectrophotometer has been used in this research to measure the colour coordinates in CIE L*a*b* and CIE L*C*h colour spaces of the stone samples, which have been surface-finished by using traditional methods (i.e. polishing and bush-hammering), advanced technologies (pure water-jet) and diamond-disc sawing. The results show that the variability of L*a*b* coordinates and chroma (C*), is much higher in some stone (Orosei Marble and Rosa Portogallo Venato) than in others (Bianco Carrara D, Verde Guatemala and Sardinian Basalt), as a result of different surface finishing. Hue (h) shows significant variation especially when Verde Guatemala is tested. Bush-hammering brings all the tested rocks to higher lightness (L*) values. When the total colour difference (ΔE*) is recorded, pure water-jetting preserves the original colour of stones similarly to the polishing with the exception of Orosei Marble. A direct correlation between ΔE* and mean average roughness (Ra) has been found. On the contrary, an inverse correlation between specular gloss values and Ra has been acknowledged. How the results can be used in practice is also explained.

Structural and optical conduct of cool white-light emanating BaGd2ZnO5:Dy3+ nanocrystals for white LEDs

An orthorhombic symmetry type BaGd2ZnO5:Dy3+ nanocrystals with luminance of cool white-color light have been fabricated via urea assisted combustion methodology. Morphological analysis revealed the agglomerated particles with non-uniform shape having crystal-size of 30–40 nm. Optimized amount of dopant (Dy3+) was examined to be x = 3 mol%, after the occurrence of quenching phenomenon. The logical pathways for quenching mechanism has been determined as non-radiative (NR) relaxations of energy via exchange-type interrelations as validated by Inokuti-Hirayama (I-H) and Dexter’s theory. Fabricated nano-powders represents two band located at 492 nm (bluish) and at 581 nm (yellowish). Band gap, decay life time and quantum efficiency of optimal powder were found as 4.71 eV, 0.7049 ms and 93.9% respectively. White-light emanation is reflected in terms of CIE color-parameters like color-coordinates of white regions (0.2869, 0.3876), color purity of 30 × 10−2 and CCT values as 7206.2 K, which have been in congruence with standard coordinates of commercial LEDs and NTSE and thus, authenticate their optimistic applicability for advanced illuminating devices.

UV resistant wood coating based on zinc oxide and cerium oxide dispersed linseed oil nano-emulsion

Natural wood is susceptible to weathering deteriorations and hence needs application of coating to increase its service life during exterior use. Due to the environmental issues associated with synthetic wood coatings, the current focus is on development of environmentally safer options for wood protection. In this paper, we propose an UV resistant and environment friendly wood coating based on zinc oxide (ZnO) and cerium oxide (CeO2) nanoparticles embedded linseed oil nanoemulsion. Preparation of nanoparticle dispersed linseed oil nanoemulsion with tween 80 as a surfactant was carried out using homogenization and ultrasonication techniques. Nanoemulsions were characterized on the basis of particle size and polydispersity index measured using dynamic light scattering technique. Morphology of nanoemulsions was examined using optical and scanning electron microscopy. Storage stability of nano emulsion was evaluated by measuring effective particle size and zeta potential over a period 14 days. Pinus radiata wood specimens were coated with ZnO and CeO2 nanoparticles (concentration 0.5–2.0% w/v) dispersed linseed oil-water nanoemulsions and UV stability of coated wood was accessed in an accelerated weathering tester by evaluating color changes on wood surfaces using CIE color parameters. Fourier transform infrared spectroscopy was used to elucidate the chemical changes on the irradiated surfaces. The results (color changes and chemical degradation) indicate significant improvement in UV shielding of wood surfaces coated with oil nanoemulsion with nano particle dispersion.

Optical characteristics of experimental dental composite resin materials

ObjectivesTo derive the K-M optical coefficients of experimental composites and compare the inherent CIE L*, a* and b* color parameters, translucency parameters and both perceptibility and acceptability thresholds. MethodsExperimental composites were prepared with 4 base-monomers: Bis-GMA, UDMA, Bis-EMA and Fit852 with TEGDMA used as a co-monomer and 3 filler:resin fractions (50:50wt%, 60:40wt% and 70:30wt%). The optical absorption (K) and scattering (S) coefficients over the visible spectra were derived. Corrected reflectivity spectra were calculated using the corrected Kubelka-Munk reflectance model and were used to calculate CIE color parameters (X, Y, Z) values. Translucency parameter (TP) was calculated using the CIEDE2000 color difference. A three-way repeated measures ANOVA was used to analyze the CIE L*a* and b* color parameters at infinite thickness. A two-way ANOVA was used to analyze the translucency parameter at 2 mm thickness. Pairwise comparisons were assessed using Bonferroni-corrected Student's t-tests. For all statistical testing α = 0.05 was used. Color parameters (ΔE00) were calculated for every experimental composite using the CIEDE2000 color differences. Perceptibility threshold (PT), acceptability threshold (AT) and translucency differences (ΔTP) were used to compare experimental composites in both filler fraction within every resin and every resin within each filler fraction. ResultsThe statistical analysis revealed a 3-way interaction (P < 0.0001) between base monomer, filler and direction factors. For the translucency parameter, when comparing filler fraction within base monomers, there were statistically significant differences between the filler fraction within all base monomers. The analysis of color differences (ΔE00) of base monomers within filler fraction revealed that the comparison between experimental composites where beyond the acceptability threshold. The comparison of the differences in translucency parameter (ΔTP) of base monomers within filler fraction were beyond the perceptibility threshold, except between base monomers UT and FT. SignificanceDifferent base monomer and filler fraction combination influences the optical characteristics of experimental composites such as: light transmission, translucency, and color appearance.

Influences of micropores and water molecules in the palygorskite structure on the color and stability of Maya blue pigment

Maya blue is an ancient hybrid pigment composed of indigo and microporous palygorskite, with a fantastic hue and outstanding stability. Its color-causing and stabilization mechanism are unsolved problems. In this work, different palygorskite materials were obtained by heating at 180, 300 and 570 °C, with raw palygorskite as a reference. Maya blue-like pigments were prepared from these palygorskite materials and solid indigo. The microporous structure of palygorskite and the status of inside water molecules were investigated by thermal analysis, X-ray diffraction, Fourier transform infrared and microporous analysis. The color properties, chemical resistance and photostability of pigments were characterized by reflectance spectra, CIE color parameters and color differences after the attack of concentrated nitric acid, dimethyl sulfoxide, and visible light exposure equaling to about 100 years. It was confirmed that the greenish-blue and stable hybrid pigment could only be prepared when indigo molecules were inserted into the micropores of palygorskite. Zeolitic water molecules inside the micropores should be removed because they hindered the insertion of indigo molecules. The key to immobilizing indigo molecules inside micropores was hydrogen bonds between indigo and coordinated water (CO … …H–OH). This study emphasized the important role of micropores and hydrogen bonds in the synthesis of organic-inorganic hybrid pigments.

Biophysical Properties of Foamed and Solid Polymers Used in Orthotics and Prosthetics.

Orthotic and prosthetic materials should have good mechanical and antibacterial properties. Therefore, in our study, we consider four common foamed closed-cells and two solid polymeric materials regarding their mechanical behaviour and tendency for bacterial adhesion. For all materials, the surface roughness, hydrophobicity, zeta potential, tensile properties, hardness and CIE color parameters were measured. We found that foamed polymeric materials have higher roughness, higher hydrophobicity, lower Young’s modulus, lower maximum tensile strength and lower hardness than solid materials. Bacterial adhesion test measurements based on observation by scanning electron microscopy show much a lower adhesion extent of S. aureus on solid materials than on foamed materials. The measured biophysical properties could be the key data for users to select the optimal materials.

Crystal structure and optical analysis of new reddish-orange Sm3+ doped BaGd2ZnO5 nano-crystalline materials for multifunctional applications

In the present report, a new series of Sm3+ doped BaGd2ZnO5 nanomaterials emanating reddish orange light have been manufactured via an ecological, ideal and less energy consuming combustion methodology. Crystallographic investigation reports the orthorhombic symmetry type with Pbnm (62) space group. Morphological analysis examines the non-uniform agglomerated particles of 35-45 nm. Photoluminescent (PL) studies reveals about the orange red emanation from the fabricated nanomaterials by recording the PL emission spectrum, which shows a fine peak at 610 nm and also discloses that the exchange type interrelations as the main mechanism for non-radiative relaxation of energy, as validated by Inokuti-Hirayama (I-H) and Dexter's theory. Band gap, decay life time, quantum efficiency and non radiative rates of optimal powder were found as 4.84 eV, 0.607 ms, 87.84 % and 0.20 ms1, respectively. At the last, excellent luminescent performance is reflected in terms of CIE color parameters like color –coordinates (0.579, 0.420), color purity (78.88 %) and 1768 K color correlated temperature (CCT). These magnificent results certified the relevancy of the targeted nanocrystals as an auspicious agent in the manufacturing of advanced illuminating appliances like WLEDs, lasers, photonic devices, solar cell, sensors and various opto-electronic appliances.

Bacterial Adhesion on Glass–Ionomer Cements and Micro/Nano Hybrid Composite Dental Surfaces

Dental restorations need to reproduce the aspect of the natural teeth of the patient, and must be non-toxic, biocompatible, and have good mechanical properties so that they can last for longer. The aim of this study was to determine the extent of bacterial adhesion of Streptococcus mutans on four different dental material surfaces, i.e., two glass–ionomer cements (Fuji conventional and Fuji hybrid) and two ceramic composites (Micro hybrid composite and Nano hybrid composite). To understand the bacterial adhesion on these four different dental materials, various surface properties were measured: roughness, contact angle, CIE color parameters and zeta potential. We found that the greatest adhesion extent was obtained for the Nano hybrid composite surface. The pronounced adhesion is the interplay between the relatively high roughness and hydrophilicity of the Nano hybrid composite surface. Color changes upon immersing ceramic composites in red wine and black tea proved that both beverages adhered to them. Black tea adhered more intensively than wine, and showed a higher inhibitory effect on the growth of Streptococcus mutans and Staphylococcus aureus.

Chromaticism differentiations: A study of the diversified aesthetic appeal of the Ghiandone granite range

This paper presents the results of the study of the change in colour of the Ghiandone granite, which is typically used for ornamental purposes, and of all its mineral constituents, whenever undergoing different surface finishings. Changes in roughness as well as gloss were recorded, and put in relation to CIE colour parameters. The study was carried out by using a spectrophotometer, in order to measure the colour coordinates in CIE L*a*b* and CIE L*C*h colour spaces of those stone samples which have been treated following traditional methods (i.e. polishing, bush-hammering and flaming) and advanced technologies (i.e. pure water-jet and abrasive water-jet); sawplane surfaces (from traditional gangsaw and diamond disk) were also considered in this study. The results show that lightness (L*) is the colour coordinate that experiences a higher variation when different surface finishings are applied, especially bush-hammering. In the CIE L*C*h colour space, polished and pure water-jet finished samples are characterized by higher chroma values than the others samples which are featured by higher lightness. Hue doesn't show any significant variation. When the total colour difference (ΔE*) is measured, pure water-jet also preserves the original colour of stone and minerals, similarly to the polishing. An inverse correlation between specular gloss values and mean average roughness have been documented.

Influence of reflective foil on persimmon (Diospyros kaki Thunb.) fruit peel colour and selected bioactive compounds

The purpose of this work was to investigate how to overcome the negative effect of anti-hail netting on the photosynthetic photon flux density (PPFD) in persimmon trees and persimmon fruit colour, flesh firmness, total soluble solids (TSS) and individual carotenoid and phenolic compound contents (determined via HPLC-MS) under a hail net with the use of reflective foil. Reflective foil increased the PPFD on the lower side of the fruits, while there was no significant difference on the upper side compared to those of the control group. The CIE colour parameters a* and h° indicated more intense red colouration of the fruits in the foil treatment than those in the control. Among carotenoids, the content of β-carotene increased, and the content of zeaxanthin decreased in fruits in the reflective foil treatment group, while the content of other carotenoids was not affected by the reflective foil. Among individual phenolic compounds in the persimmon peel, greater light intensity significantly influenced all three phenolic compound subgroups: phenolic acids, flavan-3-ols and flavonols. The content of gallic acid in the persimmon flesh increased the most, while other phenolics did not show any significant differences in concentrations between the foil and control groups. This study is the first to examine the influence of reflective foil on bioactive compounds in persimmon fruit. The use of reflective foil in persimmon orchards improves persimmon fruit colour and selected bioactive compound contents.

Macrostructure and optical studies of hydroxypropyl cellulose in pure and Nano-composites forms

In the present study, composites of hydroxypropyl cellulose and iron (III) oxide nanoparticles (HPC:Fe2O3 NPs) were prepared in different ratios (20:0.5, 20:1, 20:1.5 and 20:2 wt:wt). Variations in the group coordination of the prepared composites in the IR region were employed. The reflectance spectra in the visible region (400–700 nm) were followed to characterize and reveal the relationship of the structure properties of the prepared nanocomposites. The CIE tristimulus values and color parameters as well as the location on the chromaticity diagram were determined. The variations in the optical parameters such as; absorption coefficient, absorption edge, band tail width and band gap energies, extinction coefficient and color strength were determined as a function of α-Fe2O3 NPs concentrations. The results of the FTIR spectra noticed that by increasing the concentration of Fe2O3 NPs in the mixture, variations in the intensity, area, band width, and the transmittance values of some bands were observed which indicate that change in the vibrational bonds and in the molecular configuration of HPC was occurred. The location of the α-Fe2O3 NPs concentration on the chromaticity diagram was different and confirmed the change in the colors of the investigated composites. The obtained variations in the optical parameters by increasing the presence of α-Fe2O3 NPs may be due the induced structural change in the system of HPC. In conclusion, increasing the existence of α-Fe2O3 NPs in the HPC network has great effect on improving the performance properties of hydroxypropyl cellulose.

Modelling the kinetics of mass transfer and change in colour during deep fat frying of green peas (Pisum sativum L.) at different frying temperatures

The investigation was carried out to study the mass transfer and change in colour during deep fat frying green peas (Pisum sativum L.) at different frying temperature ranging from 120 to 180 °C. The results showed that the kinetics of moisture loss (kx) and fat uptake (ky) during deep fat frying followed first order kinetic equation (R2 > 0.96, p < 0.001). The kinetic rate constant for moisture loss was significantly (p < 0.05) increasing from 0.484 to 2.212 min−1 with increase in temperature, where as the oil uptake was increasing from 0.241 to 0.371 min−1 with increasing temperature. The CIE color parameters were significantly (p < 0.05) affected by frying time as well as frying temperature. The change in CIE colour parameters such as lightness (L*), Total colour difference (∆E) and dominant wavelength (λd) were described by first order kinetic equation, where as, other colour parameters such as greenness-redness (a*), yellowness (b*), chroma (c*) and hue angle (h*) were described by zero order kinetic equation. The degradation of chlorophyll content of green peas was described by first order kinetic equation and rate constant varied from 0.0861 to 0.1872 min−1 with increase in frying temperature. The temperature dependency of rate constants was described by Arrhenius equation. The activation energy of mass transfer, change in colour values and degradation of chlorophyll varied from 3.94 to 39.28 KJ/mol. A significant correlation was observed among mass transfer, colour and pigment content parameters during deep fat frying of green peas at different frying conditions.

In vivo evaluation of tooth colour alterations during orthodontic retention: A split-mouth cohort study.

To assess in vivo colour alterations of teeth following removal of fixed orthodontic appliances during retention. The Department of Orthodontics at the Aristotle University of Thessaloniki. Forty-eight patients after orthodontic treatment. Debonding and cleaning procedures after orthodontic treatment were performed using two different carbide burs attached to a low or high-speed handpiece, respectively, in a non-blinded cohort study with split-mouth design. Spectrophotometric colour data of teeth were recorded: (a) after debonding, (b) three months later, prior to and following finishing with Soflex discs, and (c) after 1year. The CIE Lab colour parameters were measured for each tooth, and the corresponding ΔΕ differences were calculated. The effect on colour was assessed with 3-way mixed ANOVA and Bonferroni's comparisons test (a<0.05). Orthodontic debonding and cleaning procedures were found to have statistically significant effects on the CIE colour parameters of treated teeth, since the L* values decreased 0.6 units (P<0.001), a* values were stable (0.0 units) and b* values increased 1.4 units (P<0.001), during the first retention year. Finishing temporarily decreased the enamel colour differences. Total ΔΕ differences for all types of teeth measured ranged from 1.4 to 2.1 units. The greatest changes were exhibited during the first 3months in teeth on which high-speed rotary instruments were used (1.6 units). The clinical relevance of this study points out that the colour of natural teeth following removal of fixed orthodontic appliances changes in long-term.