CIELAB Color Parameters Research Articles

Near infrared spectroscopic investigation of the thermal degradation of wood

In the present paper changes in the near infrared (NIR) spectra and color parameters of wood ( Dalbergia sissoo) after thermal treatment are reported. The color change of the wood upon heating was analyzed by the CIELAB color parameters. The degradation of wood upon heating was determined by differential scanning calorimetery (DSC). Wood degradation involved from 50 °C to 80 °C changes in the amorphous region in cellulose took place, from 100 °C to 130 °C changes were observed in physically bonded water and from 150 °C to 160 °C degradation of hemicelluloses took place. The phase transition of cellulose took place at about 175 °C and changes in the crystalline region in cellulose were observed at 210 °C. The significant changes are observed in the lignin at elevated temperatures. The change in the color of the wood on increasing temperature is related to the degradation of hemicelluloses. NIR spectroscopy was found to be a powerful tool to determine the physicochemical structural changes in wood on heat treatment.

Relationship between color and pigment production in two stone biofilm-forming cyanobacteria (Nostoc sp. PCC 9104 and Nostoc sp. PCC 9025)

Previous studies have provided evidence that color measurements enable on site quantification of superficial biofilms, thereby avoiding the need for sampling. In the present study, the efficiency of color measurements to evaluate to what extent pigment production is affected by environmental parameters such as light intensity, combined nitrogen and nutrient availability, was tested with two cyanobacteria, Nostoc sp. strains PCC 9104 and PCC 9025, which form biofilms on stone. Both strains were acclimated, in aerated batch cultures for 2 weeks, to three different culture media: BG-11, BG-110, and BG-110/10 at either high or low light intensity. The content of chlorophyll a, carotenoids, and phycocyanins was measured throughout the experiment, together with variations in the color of the cyanobacteria, which were represented in the CIELAB color space. The results confirmed that the CIELAB color parameters are correlated with pigment content in such a way that variations in the latter are reflected as variations in color.

Does the pelleting process affect the nutritive value of a pre‐starter diet for suckling piglets? Ex vivo studies on mineral absorption

The effects of pelleting on the extent of the Maillard reaction (MR) and on calcium, magnesium and zinc solubility and absorption were analysed in a conventional pre-starter diet for suckling piglets. Development was tested measuring colour, absorbance (280/420 nm), fluorescence, residual free lysine, furosine, hydroxymethylfurfural (HMF) and furfural contents before and after pelleting. Fluorescence, absorbance and mineral solubility were also measured after in vitro digestion of diets. The effects on mineral absorption were tested using Caco-2 cells. MR indexes confirmed the development of the reaction during the pelleting of this particular diet compared with the meal diet. The CIE-Lab colour parameters showed a decrease in luminosity (L*) and progress of the colour to the red zone (a*) in the pelleted diet. A 36% decrease in free lysine content was observed. Significant correlations were observed between fluorescence intensity and furosine levels, HMF and furfural. The pelleting process did not modify calcium and magnesium solubility after in vitro digestion, but soluble zinc increased. The efficiency of calcium and zinc transport across Caco-2 cell monolayers was greater in the pelleted diet. Evidence of MR development is shown, resulting in various nutritional consequences. Optimisation of pelleting could result in a better formulation of diets for feedstuffs.

EFFECT OF POLYGODIAL ON MECHANICAL, OPTICAL AND BARRIER PROPERTIES OF CHITOSAN FILMS

ABSTRACT The mechanical, optical and barrier properties of chitosan films containing polygodial (0.0, 2.7, 13.9, 25.0 mg/g of chitosan) were studied. Water vapor permeability (WVP), tensile strength, percentage elongation at break, CIELab color parameters, hue angle and chroma of films were determined. Fourier transform infrared (FTIR) was also performed to determine functional group interaction between the matrix and polygodial added. The use of polygodial resulted in stronger films without losing their extensibility and with low WVP. Films became darker with yellow-green coloration with increasing polygodial concentration. Polygodial added to chitosan films did not have any interaction with the amino groups of chitosan as measured by FTIR. Polygodial as a natural dialdehyde can effectively be applied to enhance some physical properties of edible films prepared with chitosan. PRACTICAL APPLICATIONS There has been an increased interest in the study of edible–biodegradable packaging films during the last decade, offering an alternative and partial solution to the problem of accumulation of solid waste composed of synthetic inert polymers, and chitosan films has been studied with this purpose. Furthermore, replacing synthetic additives by natural compounds such us polygodial can be a suitable manner to improve some physical properties of those chitosan films.

Statistical correlation between flavanolic composition, colour and sensorial parameters in grape seed during ripening

The aim of this work has been to determine the correlations between sensory analysis, colour and content of main flavanols present in seeds. For this, the flavanic composition of grape seeds with different degrees of maturity was analysed by HPLC–DAD-MS and the obtained results were correlated with CIELab colour parameters, perceived colour (C), hardness of the seed (HS), tannic intensity (TI) and astringency (A). Multiple linear regression analysis (MLR) with the variables showing significant correlations ( p < 0.05) was also performed. Grape seeds undergo important decreases in the content of catechins and procyanidin oligomers during ripening. Epicatechin-(4-8)-epicatechin-3-O-gallate (B2G) and (−)-epicatechin-3-O-gallate (ECG) are the flavanolic compounds whose contents decrease most. The changes in the phenolic composition accompany changes in TI, A and HS. The total content of flavanols in the seed is not the only factor affecting these attributes, since samples containing higher contents in flavanols can exhibit less astringency and tannic intensity than others with lower ones. The qualitative profile of the seeds is, therefore, also responsible for the sensations elicited in the mouth. A and HS parameters are more affected by the presence of galloylated dimeric procyanidins in the molecule than TI. CIELab colour parameters of seeds have high correlation coefficients with many flavanolic compounds. ECG was the compound most related to these parameters.

Thermal Degradation Kinetics of Carotenoids in a Cashew Apple Juice Model and Its Impact on the System Color

The thermal degradation kinetics of the main carotenoids of cashew apple in a juice model system was studied by HPLC and related to the changes of its CIELAB color parameters. Similar isomerization equilibrium constants and activation energies were observed for both all-trans-beta-carotene and all-trans-beta-cryptoxanthin. The curves for the decay of the main carotenoids and color changes showed a biphasic behavior that was best fitted by a biexponential equation. For the same heating conditions (60 or 90 degrees C), similar rate constants for the fast (gamma(1)) and slow (gamma(2)) decays were obtained for both the chemical (carotenoids) and physical (color) parameters monitored in the present research. This fact indicates that color parameters, such as DeltaE*, are good predictors of both all-trans-beta-cryptoxanthin and all-trans-beta-carotene thermal degradation. A mechanism for thermal carotenoid degradation was proposed, involving parallel irreversible and reversible coupled reactions of both the initial all-trans-beta-cryptoxanthin and all-trans-beta-carotene to yield, respectively, degradation compounds and mono-cis isomers.

Color stabilization of porcine hemoglobin during spray-drying and powder storage by combining chelating and reducing agents

This work focuses on the effects of adding a chelating agent – such as nicotinic acid (NA, 2% w/v) or nicotinamide (Nam, 2.5% w/v) – along with glucose as a reducing agent (G, 10% w/v) to fresh porcine hemoglobin in order to stabilize its red color during spray-drying and powder storage at room temperature. Correlations between the CIELAB color parameters and the relative percentages of the different hemoglobin derivatives (liganded and deliganded ferrohemoglobin, and methemoglobin) were analyzed. The results indicate that, although little effects could be observed for any of the combined treatments on fresh hemoglobin, they were effective against pigment autoxidation during dehydration and subsequent storage. From the results, it can also be concluded that glucose was the main contributor to the color stabilization of the hemoglobin powder, probably due to its high water retention capacity.

Colour measurement as a proxy method for estimation of changes in phase and chemical composition of fly ash formed by combustion of coal

Influence of technology on colour changes of fly ashes was studied in relationships with their chemical and phase composition. Dry bottom boilers at the Detmarovice Power Plant (the Czech Republic) were selected for this study. Combustion tests were performed using mixture of coal and mineral oil residues at the minimum and maximum output of the power plant. Fly ashes for chemical analysis, phase analysis and colour measurements were sampled from the four sections of electrostatic fly ash precipitator. Colour parameters indicate relationships with concentrations of elements which are preferentially bound in silicate matrix. The maximum output of power plant increases the concentration of glass which has decisive influence on values of colour parameters. The changes of colour parameters can indicate the conditions of the technological process. Relationships between colour and constituents of the fly ash are expressed by CIE Lab colour parameters.

Comparison of physicochemical, microscopic and sensory characteristics of ecologically and conventionally grown crops of two cultivars of tomato (Lycopersicon esculentum Mill.)

AbstractBACKGROUND: Numerous studies have compared ecologically produced foods with conventionally produced competitors, with contradictory results. In this work we investigated the physicochemical, microscopic and sensory properties of two tomato cultivars (Lladó and Antillas), which were grown both ecologically and conventionally.RESULTS: The physicochemical variables size, weight, firmness, total acidity, pH, total solids content, lycopene content and CIELab a*, b*, a*/b*, C* and h* were all significantly influenced by cultivar, as were the sensory variables external colour, internal colour, external aroma intensity and flavour persistence. Compared with conventionally grown tomatoes, ecologically grown tomatoes had larger total solids contents and larger values of the CIELab colour parameters b*, C* and h*, but smaller sizes and weights and smaller values of the CIELab parameter ratio a*/b*; however, these physicochemical differences were insufficient for growing method to have a significant influence on any of the sensory attributes that were evaluated. Microscopy showed the influence of cultivar on lycopene content, but no other structural differences were observed between the two cultivars or between tomatoes grown by different methods.CONCLUSIONS: The statistically significant differences found in this study were mainly between cultivars rather than between tomatoes grown using different management practices. Copyright © 2009 Society of Chemical Industry

Monitoring dental erosion by colour measurement: An in vitro study

Objectives The aim of this study was to develop a method to monitor dental erosion by evaluation of the colour change of teeth as a function of enamel loss, and to evaluate the reproducibility of the method used. Methods Light reflectance spectra of 12 extracted human incisors were measured using a spectroradiometer and diffuse illumination. From these spectra CIELab colour parameters L*, a* and b* were calculated. Erosive dental wear was simulated by incrementally removing enamel layers. We monitored the change of the colour parameters as a function of the enamel thickness removed. A clinical situation using a phantom head and ambient illumination was simulated with 8 incisors. In this set-up colour change due to polishing was evaluated. The teeth were immersed in coffee and tea to estimate the effects of nutritional dyes, and so, to determine reproducibility of the method used in clinical situations. Results A relationship between tooth colour measured and enamel loss was found, in particular for the b* value. The relation between the b*-value and the enamel thickness removed showed a slope of 15 ± 3 mm −1, if the remaining enamel layer had a thickness of less than 0.5 mm. Polishing of the teeth made them less yellow. Immersion in coffee darkened the teeth, but immersion in tea had no significant effect. Conclusions Due to individual variation, it was impossible to use this relationship to estimate the remaining enamel thickness, but the method presented may be suitable for monitoring progression of erosive enamel loss.

Use of Chromameter‐Measured Color Parameters in Estimating Color‐Related Soil Variables

Soil color is a soil property that may be used as an interpreting index in estimating processes and properties. Quantifying color allows one to obtain information for rapidly estimating the related processes in soils. CIELAB color parameters L*, a*, and b* of ground (air‐dried and sieved) soil samples and aggregate surfaces of four soil profiles formed in calcareous colluviums in northern Turkey were analyzed. Values of color parameters measured in ground and intact soils were compared and related to soil properties by the regression technique. Results revealed that the L* value obtained with a ground soil sample was a significant predictor of organic matter in A horizons (p < 0.001). Although calcic horizons yielded the highest L* values, no significant relationship was obtained between calcium carbonate contents and lightness of soils in any of horizons studied. The parameters of b* could adequately be used to quantify dithionite‐extractable iron oxide contents in soils studied. The results further showed that the CIELAB color parameters obtained with ground samples were more informative than that of aggrevated samples in relating color parameters to soil properties.

Yellow and red ochre pigments from southern Portugal: Elemental composition and characterization by WDXRF and XRD

Three different yellow and red ochre pigments geological sources from Alentejo— Terras rossas, schist units and weathered iron ore deposits—were studied by elemental and phase analysis complemented with Munsell and CIELAB colour parameters. Central aims were to underline the mineralogical and chemical distinctiveness of natural pigment sources and establish a connection between local geology and use of specific colour pigments in traditional lime wash mural paintings. According to the chemical composition the Fe abundance is 6 times higher than average crust values. The Terras Rossas are characterized by higher Ca contents. In yellow and red schists, phyllosilicates are major minerals, so pigments from these units are enriched in K and Rb. Besides Fe, the pigments from weathered ores are enriched in metals like Pb, As, Cu, and Zn, which can be used as fingerprints.

Consequence of muscle hypertrophy on characteristics of Pectoralis major muscle and breast meat quality of broiler chickens1

The structural and metabolic characteristics of the pectoralis major (P. major) muscle (i.e., breast muscle) and the quality of the resulting meat were studied in relation to breast muscle fiber development in broiler chickens. Six hundred birds originating from a commercial, grand parental, male heavy line (Hubbard-Europe, Châteaubourg, France) were kept under conventional breeding methods until their usual marketing age of 6 wk. For all birds, the plasma creatine kinase activity and the P. major muscle fiber cross-sectional area (CSA), glycolytic potential, lactate content, pH at 15 min postmortem, as well as the ultimate pH, CIELAB color parameters [lightness (L*), redness (a*), and yellowness (b*)], and drip loss of breast meat, were measured. Increased breast weight and yield were associated with increased fiber CSA, reduced muscle glycolytic potential, and reduced lactate content at 15 min postmortem. Therefore, P. major muscle exhibiting larger fiber CSA exhibited greater pH at 15 min postmortem and ultimate pH, produced breast meat with lower L* and reduced drip loss, and was potentially better adapted to further processing than muscle exhibiting small fiber CSA.

Maillard reaction indicators in diets usually consumed by adolescent population

Contents of some indicators of the Maillard reaction (MR) in two diets adjusted to the adolescent requirements are compared: the A-diet, usually consumed by the adolescent population containing their preferred foods cooked by the culinary techniques more frequently chosen; and the B-diet, with the same foods, except those industrially processed and with high content of Maillard reaction products (MRP), cooked in softer processes to minimise the MR. Aliquots of a lunch-dinner (LD) and breakfast-afternoon (BA) snack pools separately from both diets were ground and lyophilised. Fluorescence associated to MRP, CIELAB colour parameters, furosine, hydroxymethylfurfural (HMF), carboxymethyllysine (CML) and sugar contents were investigated in the samples. Significant losses of lightness were manifested in A samples compared to the B ones. Fluorescence intensity was significantly higher in the LD and BA samples from the A-diet. Furosine measured in the A-diet was similar to that found in the B-diet. However, HMF content was significantly higher in the A-diet, as well as CML. Data showed significant higher levels of advanced MRP in the usual diet. Thus, MRP intake associated to alimentary pattern in the adolescence population might be studied in order to assess the health implications of the MRP consumption and its possible synergic effect with endogenous advanced glycation endproducts.

Chemical Composition and Lipid Fraction Characteristics of Aleppo Pine (Pinus halepensis Mill.) Seeds Cultivated in Tunisia

The proximate composition of Aleppo pine ( Pinus halepensis Mill.) seeds cultivated in Bizerta (Tunisia) were investigated for their fatty acid composition, and their thermal and physical properties of lipid fraction. The proximate analysis of pine seeds showed the following composition (on a dry-weight basis): protein 22.7%, oil 43.3%, ash 8.3% and total carbohydrate 25.7%. Potassium, magnesium and calcium were the predominant mineral elements present in the seeds and reached, together, about 1%. Oleic and linoleic acids were the major unsaturated fatty acids (27.3 and 48.8%, respectively), while the main saturated one was palmitic acid (8.75%). Myristic, myristoleic, palmitoleic, margaric, margaroleic, stearic, linolenic, arachidic, eicosenoic, eicosadienoic, eicosatrienoic, behenic and lignoceric acids were also detected. Thermal profile of Pinus halepensis Mill. seed oil, determined by its DSC melting curve, showed that the entire liquefaction of the Aleppo pine seed oil occurs at 8°C. CieLab colour parameters ( L*, a*, b*), oxidative stability by Rancimat test and viscosity were also determined. Physico-chemical properties of the oil include: saponification number 190, peroxide value 3.18, iodine index 117, and a low acidity of 0.61%. Results suggested that the production of oil from Pinus halepensis seeds could provide a potential use in food, pharmaceutical, cosmetics and other non-food industries.

Aging Effect on the Pigment Composition and Color ofVitis viniferaL. Cv. Tannat Wines. Contribution of the Main Pigment Families to Wine Color

Red wines made from Vitis vinifera L. cv. Tannat grapes are known to possess high contents of tannins and intense color, features that are responsible for the originality of these wines. This work aimed to study the evolution of the pigment composition and CIELAB color parameters as Tannat wines become older, as well as to establish the contribution to wine color of the main pigment families. Tannat wines produced in Uruguay from grapes of the same vineyard in six consecutive vintages (1998-2003) and Tannat grapes of the 2003 harvest were analyzed by means of HPLC-DAD-MS and UV-vis spectrometric techniques. The correlations between the different pigment families and the CIELAB parameters revealed the importance of the variations of the percentage, found in anthocyanins and flavanol-anthocyanin acetaldehyde-mediated condensation products (decrease) and pyranoanthocyanins and direct condensation products (increase), in the modification of the color from purple-red hues to more orange-red ones. The color suffered qualitative rather than quantitative changes, that is, the hue (h*ab) increased, whereas the chroma (C*ab) and lightness (L) did not show a defined trend with time.

Chromatic characterisation of three consecutive vintages of Vitis vinifera red wine : Effect of dilution and iron addition

Both standard and CIELAB colour parameters have been evaluated for three consecutive vintages of Vitis vinifera (Tempranillo variety). A simple and straightforward relationship between CI and L * has been derived. Dilution effects on colour for samples under fermentation and for several commercial wines have been studied under pH controlled conditions. Disruptions of equilibria responsible for colour at the typical wavelengths upon addition of iron have been assessed.

Effect of whey protein- and hydroxypropyl methylcellulose-based edible composite coatings on color change of fresh-cut apples

Edible composite coatings were prepared from whey protein isolate (WPI), whey protein concentrate (WPC) or hydroxypropyl methylcellulose (HPMC) as the hydrophilic phase, and beeswax (BW) or carnauba wax (CarW) as the lipid phase. Apple pieces were coated with the emulsion coatings and weight loss and color (CIELAB color parameters, L*, a*, b*, and browning index (BI)) were measured during storage. Results show that apple pieces coated with whey protein-based coatings had higher L*-, and lower b*-, a*-, and BI-values than HPMC-based coated and uncoated apple pieces, which indicate that whey proteins exert an antibrowning effect. Coatings containing BW were more effective in decreasing enzymatic browning than coatings containing CarW. The sensory panel differentiated samples coated with whey protein-based coatings from samples coated with HPMC-based coatings. However, differences due to lipid type were less evident at the end of the storage time. Coating application did not reduce weight loss in fresh-cut apples, probably due to the high relative humidity of the product.

Relationships between chemico-mineralogical composition and color properties in selected natural and calcined Spanish kaolins

A total of 21 raw, washed and ground Spanish kaolins were studied. Kaolinite, mica, quartz, feldspars and occasionally anatase and analcime were present. Calcined samples in which the kaolinite had been transformed into metakaolinite (650 °C, 3 h), as shown by X-ray diffraction and observed using SEM were also studied. These samples featured particles with openings and a lateral loss of laminar continuity, generated spaces, joined crystal edges and superficial coatings which appeared to be fused to the surface of the aggregates. Whiteness and tint indices (W 10, T w,10), revealed that only nine kaolins could be considered white (limits of CIE Colorimetry, 1986. 2nd ed. CIE Publication No.15.2. Vienna: Central Bureau of the CIE), though upon calcination, this number is reduced to three. Calcinating also produced coloring and reddening of the samples. The CIELAB color parameters significantly correlated with compositional properties such as mineralogy, the chemical analysis of elements, the free oxide contents (Al 2O 3, SiO 2, Fe 2O 3) extracted with ammonium oxalate and with citrate–dithionite–carbonate, and trace elements. In the non-calcined kaolins: C ab* is positively related to SiO 2 and negatively to the percentage of kaolinite; L* is negatively related to K 2O; h ab is negatively related to K 2O and MgO; and W 10 is positively related to the percentage of kaolinite and negatively to the percentages of mica, K 2O, MgO, MnO and free Fe 2O 3. The calcined samples showed correlations of h ab and L* (positive) and of C ab* (negative) with the proportions of both elemental Al and the Al extracted as free oxides. There are nonsignificant differences between the L* of calcined and non-calcined kaolin samples, meaning that both samples fulfill the requirements of high lightness for use in the paper industry.

Effect of sodium chloride, sodium tripolyphosphate and pH on color properties of pork meat

AbstractThe myoglobin state determines the color of meat, and most of the additives used in processing meat products cause color changes. The aim of this study was to quantify the effect of pH (4.0, 5.0 and 6.0), sodium chloride (0, 1.5 and 3.0%) and sodium tripolyphosphate (0, 0.15 and 0.30%) on the color properties and myoglobin states of pork meat (Subscapularis muscle). CIELAB color parameters (Lightness, redness, yellowness, chroma and hue) and reflectance spectrum, between 400–700 nm, were obtained. The different myoglobin forms (deoxymyoglobin, oxymyoglobin and metmyoglobin) were quantified using K/S reflectance values. Both, sodium chloride and tripolyphosphate reduced meat lightness, although the latter additive did not modify redness, yellowness, chroma or hue, but stabilized the percentage of oxymyoglobin. A decrease in pH and the addition of sodium chloride or sodium tripolyphosphate, led to an increase in the Metmyoglobin percentage. © 2003 Wiley Periodicals, Inc. Col Res Appl, 29, 67–74, 2004; Published online in Wiley Interscience (www.interscience.wiley.com). DOI 10.1002/col.10215