Color Change Of Samples Research Articles

Colour, phenolic content and antioxidant capacity of some fruits dehydrated by a combination of different methods

The objective of this study was to improve product quality of dehydrated fruits (apple, pear, papaya, mango) using combined drying techniques. This involved investigation of bioactivity, colour, and sensory assessment on colour of the dried products as well as the retention of the bio-active ingredients. The attributes of quality were compared in regard to the quality of dehydrated samples obtained from continuous heat pump (HP) drying technique. It was found that for apple, pear and mango the total colour change (ΔE) of samples dried using continuous heat pump (HP) or heat pump vacuum-microwave (HP/VM) methods was lower than of samples dried by other combined methods. However, for papaya, the lowest colour change exhibited by samples dried using hot air–cold air (HHC) method and the highest colour change was found for heat pump (HP) dehydrated samples. Sensory evaluation revealed that dehydrated pear with higher total colour change (ΔE) is more desirable because of its golden yellow appearance. In most cases the highest phenol content was found from fruits dried by HP/VM method. Judging from the quality findings on two important areas namely colour and bioactivity, it was found that combined drying method consisted of HP pre-drying followed by VM finish drying gave the best results for most dehydrated fruits studied in this work as the fruits contain first group of polyphenol compounds, which preferably requires low temperature followed by rapid drying strategy.

A cleaner production of denim garment using one step treatment with amylase/cellulase/laccase

Denim garment is one of the most important and highly used textile clothing, regarding its exclusive features including color, versatile appearance and high strength that are widely used by young people. To create diversity in denim garment it is necessary to apply special techniques and new substances to respond the huge market demand. In this paper, bio-treatment process, using amylase, cellulase, laccase, and their combinations applied on denim garment to conduct one step bio-desizing and bio-washing producing old-look appearance garment is proposed and analyzed. The color changes of denim samples and the whiteness of the back and staining on the pocket was measured and the surface morphology of the samples were observed using Scanning Electron Microscope. The results indicated successful treatment regarding one step bio-desizing and enzymatic bio-washing using mixture of amylase and cellulase and laccase. The obtained color on the samples treated with the three enzymes has not been differed significantly with the bio-desized garment treated with cellulase or laccase and cellulase/laccase (cellulase and laccase).

Room Temperature Radiolytic Synthesized Cu@CuAlO2-Al2O3 Nanoparticles

Colloidal Cu@CuAlO2-Al2O3 bimetallic nanoparticles were prepared by a gamma irradiation method in an aqueous system in the presence of polyvinyl pyrrolidone (PVP) and isopropanol respectively as a colloidal stabilizer and scavenger of hydrogen and hydroxyl radicals. The gamma irradiation was carried out in a 60Co gamma source chamber with different doses up to 120 kGy. The formation of Cu@CuAlO2-Al2O3 nanoparticles was observed initially by the change in color of the colloidal samples from colorless to brown. Fourier transform infrared spectroscopy (FTIR) confirmed the presence of bonds between polymer chains and the metal surface at all radiation doses. Results of transmission electron microscopy (TEM), energy dispersive X-ray spectrometry (EDX), and X-ray diffraction (XRD) showed that Cu@CuAlO2-Al2O3 nanoparticles are in a core-shell structure. By controlling the absorbed dose and precursor concentration, nanoclusters with different particle sizes were obtained. The average particle diameter increased with increased precursor concentration and decreased with increased dose. This is due to the competition between nucleation, growth, and aggregation processes in the formation of nanoclusters during irradiation.

Radiation-induced reduction of mixed copper and aluminum ionic aqueous solution

Colloidal Cu–Al nanoparticles were prepared in an aqueous polyvinyl alcohol solution containing copper chloride and aluminum chloride as precursors, isopropanol as a scavenger of hydroxyl radicals, and distilled water as a solvent. The gamma irradiations were carried out in a 60Co gamma source chamber with different doses up to 120 kGy. The formation of Cu–Al nanoparticles has been observed initially by the change in color of the colloidal samples from colorless to brown. The nanoparticles properties were characterized by transmission electron microscopy, energy dispersive X-ray spectrometry, and UV–Vis spectrophotometer. At a constant Cu/Al molar ratio, size of the nanoparticles can be well controlled by varying the precursors concentration and radiation dose. The average particle diameter increases with increase of precursors concentration and decreases with increase of dose. This is owing to the competition between nucleation process, aggregation process, and ions association in the formation of nanoparticles during irradiation.

Radio-frequency heating to inactivate Salmonella Typhimurium and Escherichia coli O157:H7 on black and red pepper spice

The efficacy of radio-frequency (RF) heating to inactivate Salmonella Typhimurium and Escherichia coli O157:H7 on black and red pepper spice was investigated. A 27.12 MHz RF heating system consisted of two parallel-plate electrodes was used, with the sample being placed between them. Black peppers (whole and ground) and red peppers (+ 16 mesh, -16 + 25 mesh, and -25 mesh) inoculated with S. Typhimurium and E. coli O157:H7 were treated with RF energy during 50s for black peppers and 40s for red peppers, and color change of samples was evaluated after treatment. RF heating for 50s resulted in 2.80 to 4.29 log CFU/g reductions of S. Typhimurium and E. coli O157:H7 in black peppers and RF heating of red peppers for 40s reduced pathogens by 3.38 log CFU/g to more than 5 log CFU/g (below the detection limit) without affecting the color quality change. The results suggest that RF heating has the potential for novel thermal process to control foodborne pathogens in spice.

Pretreatment of wool/polyester blended fabrics to enhance titanium dioxide nanoparticle adsorption and self‐cleaning properties

This research aims to enhance the self‐cleaning properties of fibre‐blended fabric using surface pretreatment prior to the application of titanium dioxide nanoparticles. To this end, the polyester/wool fabric was modified, in that the wool fibres were oxidised with potassium permanganate and the polyester fibres were hydrolysed with lipase before nano processing. Butane tetracarboxylic acid was also used to enhance the adsorption of the nanoparticles and also to stabilise them on the fabric surface. The self‐cleaning properties of the fabric were examined through staining of the fabric with CI Basic Blue 9 and then discolouring by exposing to ultraviolet and daylight irradiation. Some other properties of the treated fabrics, such as water drop absorption, crease recovery angle and bending were investigated and are discussed in detail. The colour changes of different samples indicated an appropriate discoloration on the titanium dioxide‐treated fabrics after ultraviolet and daylight irradiation. Overall, the surface pretreatment of the wool and polyester fibres improved the self‐cleaning properties of the fabric significantly.

Manganese in silicon carbide

Structural disorder and relocation of implanted Mn in semi-insulating 4H–SiC has been studied. Subsequent heat treatment of Mn implanted samples has been performed in the temperature range 1400–2000 °C. The depth distribution of manganese is recorded by secondary ion mass spectrometry. Rutherford backscattering spectrometry has been employed for characterization of crystal disorder. Ocular inspection of color changes of heat-treated samples indicates that a large portion of the damage has been annealed. However, Rutherford backscattering shows that after heat treatment, most disorder from the implantation remains. Less disorder is observed in the [0 0 0 1] channel direction compared to [ 1 1 2 ¯ 3 ] channel direction. A substantial rearrangement of manganese is observed in the implanted region. No pronounced manganese diffusion deeper into the sample is recorded.

Biochemical and biophysical implications of the methods of processing and storage of Garri.

Garri samples, collected from three major-producing areas (Ihiagwu in Imo State, Aba in Abia State and Okija in Anambra State) of South-Eastern Nigeria, were packaged in three types of packages, namely, metal can (tin), plastic can can and thick gauge polyethylene bag andevaluated for long term storage effects. The proximate composition, swelling capacity, PH values, Hydrogen cyanide. (HCN) contents and particle size distribution analysis of the samples, were carried out. After packaging, the moisture contents, swelling capacity, colour and odour of the samples were evaluated on one –weekly intervals; until the end of the study lasting 10 weeks. The moisture contents were highest with Okija garri samples with a value of 17.95% followed be Aba with a value of 15.50% and lowest with Ihiagwa with a value of 13.75%. These values were higher than the 12% moisture content stipulated for safe storage of garri sample.The crude protein, ash, crude fibre and HCN contents were about the same for all the garri samples. The HCN contents were within the stipulated safe level. The swelling capacity was highest with the Ihiagwa samples. (444%), followed by Aba (400%) and Okija (342%), in that order. The particle size analysis indicated that Okija samples were finer than Aba and Ihiagwa samples. There was some increase in the moisture contents of the samples stored in metal can and plastic can packages. There was progressive decrease in the swelling capacity of the stored samples, with more pronounced decrease with Okija sample. There was no change in the characteristic odour and colour of the garri samples stored in the thick-gauge polyethylene packages. The results indicated that commercial garri samples from Ihiagwa, Aba and Okija in the south-eastern Nigeria stored better in thick-guage polyethylene packages than in metal can and plastic can packages. Furthermore, the higher initial moisture contents of the samples resulted in faster deterioration in garri quality.

Alternative UV Sensors Based on Color-Changeable Pigments

Photochromism is a chemical process in which a compound undergoes a reversible change between two states having separate absorption spectra, i.e. different color [1]. In our previous work we have published some solutions of problems of measuring photochromic textile sample by standard commercial spectrophotometric systems [2]. Main problem with measurement of kinetic behavior of photochromic pigments by standard spectrophotometer is relatively long time period between individual measurements (5 s) and impossibility of measuring whole color change during exposure without interruption of illumination of sample during measurement. It means, standard commercial spectrophotometers enable off-line measurement of kinetic behavior during exposure period and quasi on-line measurement during reversion period. Based on this problem, it is only possible to obtain precise data during reversion—decay process and growth process (exposure) is affected by high variability of data. Following this knowledge, we developed original experimenttal system with short time scanning of color change of photochromic samples during growth and decay period of color change. In this study it is presented new view on the relationship between intensity of UV-A radiation and color change half-life t1/2. Via this relation, it is demonstrated the possibility of the flexible textile-based sensors construction in the area of the radiation intensity identification.

The Effect of Pre-Treatments in Combination with Hot Air, Vacuum and Hot-a Microwave Drying Methods the Progress of the Drying Process, and Textural, and Colour and Rehydration Rate on Button Mushroom (Agaricus bisporus)

The effect of pre-treatments in combination with hot air, vacuum and hot-a microwave drying methods the progress of the drying process, and textural, and colour and rehydration rate on button mushroom (Agaricus bisporus) slices were investigated. In this work, one of the following methods: hot air, vacuum drying or microwave-assisted convective drying and also different pre-drying treatments, viz. blanching (with hot water or vapour) and sulphitation, were applied. Textural properties of button mushroom were measured during drying and rehydration using a texture analyser. The colour changes of samples during drying and rehydration were analysed applying a Hunterlab Colorimeter. During drying, hardness of mushrooms was increased. Sulphitation pre-treatment improved the structural and rehydration rate of the dried samples, but had varying effects on the colour. Microwave energy reduced drying time and can modify the structure, colour and texture strength of the final product. The effect of microwave treatment on colour varied with the type of pre-treatment applied before drying. Microwave samples showed also the highest rate of rehydration among all samples. Keywords: Microwave-assisted convective drying, Mushroom, Colour changes, Rehydration rate, Textural properties

Water production analysis and reservoir simulation of the Jilake gas condensate field

Abstract The development of the Jilake gas condensate field is dominated by production of old wells, with complication of well status, serious impact of edge-bottom water, and difficulty in development and adjustment. Through integration of formation water salinity analysis, color and density change of oil samples, diagnostic curve characteristic of modern production decline analysis and characteristic analysis of production water, the reason for water production is analyzed as follows: gas wells with low water production are affected by local connate water, while gas wells with high water production are influenced by the bottom-edge water. Integrated with domestic and overseas modeling of oil rim gas condensate reservoir, the fine geological model is built by Petrel geo-modeling software, and the approaches of non-equilibrium initialization and parameters initial value assignment is used to form the initialization model of the gas condensate field, in order to correctly portrait the oil rim and local connate water. On the basis of single-well water production analysis, the geological model is corrected through performance dynamic history match. The result provides a base and foundation for later development adjustment of this gas condensate field.

EFFECT OF NaCl AND WATER CONTENT ON EXPANSION AND COLOR OF CASSAVA AND POTATO STARCHES ON BAKING

ABSTRACT Due to the importance of the role of NaCl in starch‐based systems, the effect of NaCl and water content on specific volume, color parameters and moisture loss of cassava and potato starches was studied and response surface methodology was used to find and estimate any nonlinearity between the parameters under study. Glass transition (Tg) is one of the main factors determining the quality parameters of toasted and baked samples. Therefore, Tg of two starch systems (cassava and potato) at low water levels (<20%) as affected by NaCl and water content was investigated. Using experimental modeling, equations were obtained to relate expansion, color change and moisture loss of baked samples to salt level and water content. Differential scanning calorimetry‐measured Tg showed that NaCl had negative impact on glass/rubber transition temperature of starch–salt mixtures compared with the samples without NaCl. This could have practical implications in baking, toasting and extrusion processing of starch‐based systems.PRACTICAL APPLICATIONDue to concerns over health‐related issues of high intake of salt by the consumers, recently, the reduction of salt in different food products has become the focus of many industrial projects, conferences and workshops. In breakfast cereals, other than starch type, other added ingredients such as sugar and salt can have profound effects on the physical characteristics of final products. The inclusion of salt in breakfast cereals has some important technological roles, e.g., structure formation and flavor and color generation. Salt plays a key role in the expansion of low‐moisture extruded starch‐based products. Using the findings of this paper, one may quantify the effects of salt level on expansion and color of baked, toasted or extruded starch‐based cereal products and relate the changes to the glass rubber transition of the system.

Influences of Different Enzymatic Treatment on Denim Garment

In current study, the effects of different enzymatic treatment including acid cellulases, neutral cellulases, and combination of laccases with cellulases on denim garment were investigated. The color changes of different samples were compared by colorimetric indices for the garment surface and back and also white pocket. Abrasion resistance, tensile strength, and crease recovery angle of the samples were measured within the standard methods. Also, surfaces of the treated samples were observed by SEM. The results showed that the combination of laccases with cellulases help to improve the lightness and decrease staining on both back of garment and on white pocket.

Comment on Electrodeposited Silicate Films: Importance of Supporting Electrolyte

We have observed similar surface color changes of glassy carbon (GC) after anodic "electrodeposition" with the same electrolytes in the presence or the absence of silanes, indicating that sample color changes can arise from more than one thing and thus should not be used as the sole indicator of silica film formation. Nevertheless, the formation of silicate films during anodic electrodeposition is verified by X-ray photoelectron spectroscopy (XPS) measurements.

Color change capacity of dental resin mixed with silver methacrylate caused by light irradiation and heating

We synthesized silver methacrylate, added it to resin for dental use, and observed color changes in the resin from colorless to red-purple following light irradiation. Therefore, 0.01-0.10 wt% silver methacrylate was added to two types of resin powder, i.e., self-curing resin produced by the polymerization of a barbituric acid derivative, quaternary ammonium, and an organometallic compound (Type I), and BPO-tertiary amine resin (Type II), and samples were produced by polymerization with the attached monomer. Changes with time in the color of samples from 3 hours (new samples) to 16 days (old samples) after polymerization and also color changes of old and new samples after heating were evaluated. Subsequently, changes in color with variations in the light intensity, irradiation time, and wavelength were evaluated in terms of color differences.

Analysis of Keratin Fibre Damage under Various Surface Treatment Conditions

This paper investigates the effect of three different treatments, namely (i) sunlight exposures, (ii) bleaching and (iii) perming on the damage of the keratin fibres (with the use of human hair). Scanning electron microscopy was applied to examine the surface morphology of the samples. Hair samples appeared to be rougher and their scales diminished after the treatments. The degree of colour change of samples was measured using a diffuse reflectance spectrophotometer. All three different treatments caused a certain degree of colour change on the samples. Urea bisulphite solubility test was also employed to investigate the alkaline damage of samples.The results illustrated that the urea bisulphite solubility of samples conformably decreased when they were subject to these three types of treatments. With respect to the tensile strength property, the results indicate that the breaking load of treated samples decreased dramatically after undergoing three different types of treatments. On evaluating the test results, it was concluded that the bleaching process imparted the most severe damages to hair. The results of the different test methods were evaluated and discussed.

Thermochromism of N-Triphenylmethylsalicylideneimine Activity of the Trans-Open Enol Conformer at Low Temperature

N-triphenylmethylsalicylideneimine (MS1) represents a reversible thermal and photo-coloration system. The initial stage of the system studied was defined by means of X-ray structure analysis. Crystal structures were done at 295 and 230 K, taking into account the results of differential scanning calorimetry; basing on the DSC measurements, a pseudo-first order phase transition at 241 K was identified. According to the analysis of the luminescence spectra of MS1, low temperature favors a benzenoid-type trans-enol open form of the molecule under study. However, after UV excitation, the photochemical reaction (proton transfer and/or photoisomerization) generates the quinoid form. So, thermochromy has been interpreted as due to geometry changes of a chelate ring, and creating an open enol molecular form rather than a shift of the tautomeric equilibrium benzenoid-to-quinoid form. Below 240 K, the light-induced generation of unstable photochromic species is manifested as the sample color change (colorless-to-orange). That newly created species is of a trans-keto-type isomer of MS1 molecule with breaking hydrogen bond, and the open trans-enol form existing in the ground state is a source of that orange species.

Modeling of Lactose Crystallization and Color Changes in Model Infant Foods

Lactose crystallization and color changes in formulas containing β-lactoglobulin and gelatinized starch were investigated. Model infant formulas were prepared by colyophilization of 3 components (lactose, β-lactoglobulin, and gelatinized starch). A mixture design was used to choose the percentage of each mixture component. These formulas were stored for 3 mo at different relative humidities (RH), ranging from approximately 0 to 94.6%, to study the lactose crystallization and color changes. Crystallization kinetics was studied by gravimetric methods, and lactose state (crystalline vs. amorphous) was verified before and after storage by differential scanning calorimetry. Before storage, lyophilized lactose was amorphous, but during storage it crystallized, depending on the RH. The lactose crystallization RH depended on the quantity of β-lactoglobulin and gelatinized starch, and by increasing these quantities, the crystallization RH increased. For some formulas, the crystallization RH was noted at 3 different RH during storage. The first was noted after 1 d of storage and the second and third were observed later on, showing that crystallization is a time-dependent phenomenon. Nonenzymatic browning was studied in model infant formulas by yellow color changes of samples at 11.3, 43.2, 54.5, and 75.4% RH. In this study, 7 mathematical models were proposed to predict the moisture sorption properties and color changes at different RH, and the models were validated by experimental results.

Surface Modification of Rutile TiO<SUB>2</SUB> by Submerged Arc Discharge for Improved Photoreactivity

Titanium dioxide is well known for its photocatalytic activity, but it works effectively only in the ultraviolet (UV) range. Given the relatively low flux of solar UV that reaches earth, the potential of exploring its photocatalytic capacity for environmental protection applications is very limited. In this study, rutile, the least photocatalytic of the three existing titanium dioxide crystalline forms, was suspended in water or acetonitrile and treated with oxygen or argon plasmas, using a novel dense-medium plasma technology (submerged arc discharge). As a result of the plasma treatment, rutile particles were doped with various trace elements that originated in electrodes made of different metals. Subsequent analyses show that the photocatalytic capacity of plasma-modified rutile is comparable to or even better than that of unmodified anatase, the most photocatalytic form of titanium dioxides. The color change of TiO2 samples after plasma treatment indicates that the modified rutile absorbs visible light and may therefore work as a photocatalyst in the visible range. Given the fact that rutile can be produced in large quantity more easily and cheaply than can anatase, these results are very encouraging and open up possibilities in using rutile for photocatalytic applications in the visible range.

Efficacy of different whitening modalities on bovine enamel and dentin

Previous studies have shown that bleaching treatment may be efficient in both enamel and dentin, but it is still unknown how much the subsurface dentin contributes to the color change of teeth. This in vitro study evaluated the whitening effect of different external bleaching agents on enamel-dentin slabs and subsurface dentin. Ninety bovine teeth were distributed among six groups (A, Opalescence 10%; B, Opalescence PF 15%; C, Opalescence Quick; D, Opalescence Extra Boost; E, Rapid White; F, Whitestrips). Two enamel-dentin specimens were prepared from the labial surface of each teeth. In one of the specimens enamel was removed, resulting in a dentin (CD) disc of 1 mm high. The labial and the pulpal sides of the second specimen were ground until the remaining enamel and dentin layers of the enamel-dentin sample (ED) were 1 mm each. Whitening treatment of the ED specimens was performed according to manufacturers' instructions. Pre- and posttreatment Lab values of ED samples were analyzed using CIE-Lab. Baseline Lab values of dentin were analyzed by evaluation of the CD specimen. Finally, enamel of the ED specimens was removed and color change of the exposed dentin (D) was recorded. For all treatment agents significant color changes (DeltaE) were observed for enamel-dentin samples and subsurface dentin specimens compared to controls. In groups A-D DeltaE was significantly higher in dentin than enamel-dentin. Furthermore, L and b values of bleached enamel-dentin and subsurface dentin samples differed significantly from baseline. Treatment with the tested external whitening bleaching agents resulted in color change of both enamel-dentin and subsurface dentin samples. The results indicate that color change of treated teeth might be highly influenced by color change of the subsurface dentin.