Deepening Of Color Research Articles

Metabolome and Transcriptome Association Analysis Reveals Mechanism of Synthesis of Nutrient Composition in Quinoa (Chenopodium quinoa Willd.) Seeds.

Quinoa (Chenopodium quinoa Willd.) seeds are rich in nutrition, superior to other grains, and have a high market value. However, the biosynthesis mechanisms of protein, starch, and lipid in quinoa grain are still unclear. The objective of this study was to ascertain the nutritional constituents of white, yellow, red, and black quinoa seeds and to employ a multi-omics approach to analyze the synthesis mechanisms of these nutrients. The findings are intended to furnish a theoretical foundation and technical support for the biological breeding of quinoa in China. In this study, the nutritional analysis of white, yellow, red, and black quinoa seeds from the same area showed that the nutritional contents of the quinoa seeds were significantly different, and the protein content increased with the deepening of color. The protein content of black quinoa was the highest (16.1 g/100 g) and the lipid content was the lowest (2.7 g/100 g), among which, linoleic acid was the main fatty acid. A combined transcriptome and metabolome analysis exhibited that differentially expressed genes were enriched in "linoleic acid metabolism", "unsaturated fatty acid biosynthesis", and "amino acid biosynthesis". We mainly identified seven genes involved in starch synthesis (LOC110716805, LOC110722789, LOC110738785, LOC110720405, LOC110730081, LOC110692055, and LOC110732328); five genes involved in lipid synthesis (LOC110701563, LOC110699636, LOC110709273, LOC110715590, and LOC110728838); and nine genes involved in protein synthesis (LOC110710842, LOC110720003, LOC110687170, LOC110716004, LOC110702086, LOC110724454 LOC110724577, LOC110704171, and LOC110686607). The data presented in this study based on nutrient, transcriptome, and metabolome analyses contribute to an enhanced understanding of the genetic regulation of seed quality traits in quinoa, and provide candidate genes for further genetic improvements to improve the nutritional value of quinoa seeds.

Molecular mechanism of color deepening of ready-to-eat shrimp during storage

Color deepening occurs during storage of ready-to-eat (RTE) shrimps, which seriously affects their marketing cycle. This study investigated the molecular mechanisms of color deterioration in RTE shrimps during accelerated storage, shedding light on the pattern of change in colored products and content. The findings revealed significant occurrences of phenolic oxidation, lipid oxidation, and Maillard browning reactions during accelerated storage. Qualitative and quantitative analyses were conducted on the colored products resulting from these chemical reactions. Multivariate mathematical models were employed to analyze the phenolic oxidation products (2-methylanthraquinone and p-benzoquinone), lipid oxidation products (lipofuscin-like pigments and hydrophobic pyrroles), and Maillard browning products (pyrazines and melanoidins). These products were identified as the main contributors to the deepening of the color of RTE shrimps during storage. The outcomes of this research could enhance our understanding of the color change mechanism in thermally processed marine foods, providing valuable insights for quality maintenance and industrial advancement.

Effects of acid and aluminum stress on seed germination and physiological characteristics of seedling growth in Sophora davidii

ABSTRACT Sophora davidii, a vital forage species, predominantly thrives in the subtropical karst mountains of Southwest China. Its resilience to poor soil conditions and arid environments renders it an ideal pioneer species for ecological restoration in these regions. This study investigates the influence of acidic, aluminum-rich local soil on the germination and seedling growth physiology of S. davidii. Experiments were conducted under varying degrees of acidity and aluminum stress, employing three pH levels (3.5 to 5.5) and four aluminum concentrations (0.5 to 2.0 mmol·L−1). The results showed that germination rate, germination index, and vigor index of S. davidii seeds were decreased but not significantly under slightly acidic conditions (pH 4.5–5.5), while strong acid (pH = 3.5) significantly inhibited the germination rate, germination index, and vigor index of white spurge seeds compared with the control group. Aluminum stress (≥0.5 mmol·L−1) significantly inhibited the germination rate, germination index, and vigor index of S. davidii seed. Moreover, the seedlings’ root systems were sensitive to the changes of aluminum concentration, evident from significant root growth inhibition, characterized by root shortening and color deepening. Notably, under aluminum stress (pH = 4.3), the levels of malondialdehyde and proline in S. davidii escalated with increasing aluminum concentration, while antioxidant enzyme activities demonstrated an initial increase followed by a decline. The study underscores the pivotal role of cellular osmoregulatory substances and protective enzymes in combating aluminum toxicity in S. davidii, a key factor exacerbating growth inhibition in acidic environments. These findings offer preliminary theoretical insights for the practical agricultural utilization of S. davidii in challenging soil conditions.

Effects of Non-Enzymatic Browning and Lipid Oxidation on Color of Ready-to-Eat Abalone during Accelerated Storage and Its Control.

The deepening of color of ready-to-eat (RTE) abalone during storage leads to sensory quality degradation, which seriously affects the shelf life of products and consumers' purchasing desire. The goal of this study is to look into the causes of non-enzymatic browning and lipid oxidation, as well as how to control them, and their effect on the color of RTE abalone during storage. The control, bloodletting and antioxidants groups (lactic acid, citric acid and 4-hexylresorcinol) of RTE abalone were stored for 0, 20 and 40 days at 40 °C, respectively, to explore the rule and mechanism of the color change in RTE abalone. This research shows that RTE abalone undergoes browning during storage. Meanwhile, the content of reducing sugar, phenols and unsaturated fatty acids decreases, while the formation of lipid hydroperoxides and aldehydes increases during storage. In addition, the color change in RTE abalone during storage is mainly related to the Maillard reaction, while the lipid oxidation mainly forms pyrrole and participates in the Strecker degradation process as part of the Maillard reaction. The quality of RTE abalone can be maintained by controlling browning effectively as well as lipid oxidation through bloodletting and the addition of antioxidants to ensure that RTE abalone has high storage stability. According to our research, bloodletting and the addition of antioxidants to RTE abalone have a good application prospect and popularizing value in the storage of RTE abalone.

Metabolic profile and transcriptome reveal the mystery of petal blotch formation in rose

BackgroundPetal blotch is a unique ornamental trait in angiosperm families, and blotch in rose petal is rare and has great esthetic value. However, the cause of the formation of petal blotch in rose is still unclear. The influence of key enzyme genes and regulatory genes in the pigment synthesis pathways needs to be explored and clarified.ResultsIn this study, the rose cultivar ‘Sunset Babylon Eyes’ with rose-red to dark red blotch at the base of petal was selected as the experimental material. The HPLC-DAD and UPLC-TQ-MS analyses indicated that only cyanidin 3,5-O-diglucoside (Cy3G5G) contributed to the blotch pigmentation of ‘Sunset Babylon Eyes’, and the amounts of Cy3G5G varied at different developmental stages. Only flavonols but no flavone were found in blotch and non-blotch parts. As a consequence, kaempferol and its derivatives as well as quercetin and its derivatives may act as background colors during flower developmental stages. Despite of the differences in composition, the total content of carotenoids in blotch and non-blotch parts were similar, and carotenoids may just make the petals show a brighter color. Transcriptomic data, quantitative real-time PCR and promoter sequence analyses indicated that RC7G0058400 (F3’H), RC6G0470600 (DFR) and RC7G0212200 (ANS) may be the key enzyme genes for the early formation and color deepening of blotch at later stages. As for two transcription factor, RC7G0019000 (MYB) and RC1G0363600 (WRKY) may bind to the promoters of critical enzyme genes, or RC1G0363600 (WRKY) may bind to the promoter of RC7G0019000 (MYB) to activate the anthocyanin accumulation in blotch parts of ‘Sunset Babylon Eyes’.ConclusionsOur findings provide a theoretical basis for the understanding of the chemical and molecular mechanism for the formation of petal blotch in rose.

Anthocyanin biosynthetic pathway switched by metalloregulator PbrR to enable a biosensor for the detection of lead toxicity.

Environmental lead pollution mainly caused by previous anthropogenic activities continuously threatens human health. The determination of bioavailable lead is of great significance to predict its ecological risk. Bacterial biosensors using visual pigments as output signals have been demonstrated to have great potential in developing minimal-equipment biosensors for environmental pollutant detection. In this study, the biosynthesis pathway of anthocyanin was heterogeneously reconstructed under the control of the PbrR-based Pb(II) sensory element in Escherichia coli. The resultant metabolic engineered biosensor with colored anthocyanin derivatives as the visual signal selectively responded to concentrations as low as 0.012 μM Pb(II), which is lower than the detection limit of traditional fluorescent protein-based biosensors. A good linear dose–response pattern in a wide Pb(II) concentration range (0.012–3.125 μM) was observed. The color deepening of culture was recognized to the naked eye in Pb(II) concentrations ranging from 0 to 200 μM. Importantly, the response of metabolic engineered biosensors toward Pb(II) was not significantly interfered with by organic and inorganic ingredients in environmental water samples. Our findings show that the metabolic engineering of natural colorants has great potential in developing visual, sensitive, and low-cost bacterial biosensors for the detection and determination of pollutant heavy metals.

Transcriptional analysis of the early ripening of ‘Summer Black’ grape in response to abscisic acid treatment

Berry quality and harvesting time affect grape (Vitis vinifera L.) market values. Abscisic acid (ABA) applications improve fruit quality and hasten ripening in grapes. However, the molecular mechanisms behind these promotive effects, especially ripening acceleration, remain unclear. Here, treatments of different ABA concentrations were applied to ‘Summer Black’ grape from véraison onwards. The ABA applications accelerated berry ripening and improved quality attributes, such as increased sugar and anthocyanin accumulations, as well as a deepening of color. RNA sequencing was performed to characterize the gene expression involved in ripening-related processes. A total of 1,880 non-redundant differentially expressed genes were identified by paired-comparisons between the ABA-treated and control samples at three sampling time points. The transcripts associated with starch and sucrose metabolism, flavonoid biosynthesis, and flavone and flavonol biosynthesis were significantly overrepresented. The change in the anthocyanin content following ABA treatments coincided with the expression patterns of key structural genes and an R2R2-MYB transcription factor associated with anthocyanin synthesis. Additionally, genes involved in both sucrose transportation and metabolism, such as HEXOSE TRANSPORTER and INVERTASE, had increased expression levels after ABA treatments, which was consistent with the responses of sucrose-relate enzymes. Thus, we hypothesize that ABA applications regulate many genes involved in flavonoid biosynthesis, sucrose metabolism and sugar transport that accelerate anthocyanin and hexose accumulation, thereby improving grape quality and allowing earlier harvests. These results provide extensive candidate genes involved in the ripening process under ABA treatment in grapes.

Comparative analysis of the effects of novel electric field frying and conventional frying on the quality of frying oil and oil absorption of fried shrimps

Production of high-quality fried foods with low oil content receives considerable attention from consumers and producers. The effects of electric field frying (EFF) and conventional frying (CF) on the physicochemical properties of frying oil, the oil absorption behavior, and the microstructural changes in fried shrimps were compared and evaluated in this study. Results showed the application of EFF could delay the degradation of frying oil evidently compared with CF. The increasing rate of total polar compound content, acid values, viscosity, and color deepening of EFF oil was slower (p < 0.05) than that of CF oil during the prolonged frying. The analysis of the results of low field nuclear magnetic resonance (LF-NMR) measurements confirmed our findings. In addition, the fried shrimps produced by EFF had reduced oil content (p < 0.05), increased water retention (p < 0.05), even oil distribution, and decreased microstructure damage via the observation of magnetic resonance imaging, confocal laser scanning microscope (CLSM), and scanning electron microscope. Results may provide ideas for producing high-quality fried products with low oil content and delaying oil degradation during frying.

냉동 방법이 품종별 복숭아의 품질에 미치는 영향

Peaches have a short shelf life and harvesting periods, so large quantities are distributed in a short time. Hence, these causes have some problems to derive low price of peaches, and this is possible to use the form of frozen fruit to overcome the difficult situation of raw fruit storage and to supply materials for processing. The purpose of this study is to investigate the effect on the quality of peach flesh according to freezing conditions and the quality after freezing-thawing by varieties to provide basic data for the production of processed products using peaches. Results shown that the harvested peaches were frozen at -20, -40℃ by convectional method, -40℃ by immersion method, and thawed at 5℃ for analysis. According to the results of this study, when peaches were frozen and thawed by varieties, browning was observed regardless of freezing conditions, resulting in a deepening of color. The color difference of peach varieties with yellow flesh was lower than that of white ones and it is indicating that the peaches with yellow flesh had less color change than the white ones after thawing. In addition, the hardness tended to increase after freezing and thawing, and it means that the peach is suitable for freezing storage because of its rigidity in freezing. Varieties suitable for cryopreservation were selected from the yellow and white flesh peaches. Therefore, current study can be used as basic data for companies to manufacture frozen fruits.

Molecular Distillation-Induced Deacidification of Soybean Oil Isolated by Enzyme-Assisted Aqueous Extraction: Effect of Distillation Parameters

Soybean oil isolated by enzyme-assisted aqueous extraction (EAE) was subjected to molecular distillation-induced deacidification, and the effects of evaporator temperature, scraper speed, and feed flow rate on oil quality (acid value, color, peroxide value, p-anisidine value, tocopherol content, and fatty acid content) were evaluated to determine the suitable deacidification conditions. Fatty acid content was largely unaffected by evaporator temperature and scraper speed, while an increase of these parameters decreased tocopherol content as well as acid, peroxide, and p-anisidine values and resulted in Lovibond color deepening. The increase of feed flow rate had an opposite effect on the above quality indices. As a result, molecular distillation of EAE-produced soybean oil under suitable conditions (evaporator temperature = 180 °C, scraper speed = 220 rpm, feed flow rate = 4 mL/min) was found to afford a high-quality deacidified product in an environmentally friendly way.

Effects of polyploidization on petal characteristics and optical properties of Impatiens walleriana (Hook.)

Impatiens walleriana (Hook.) (2n = 2x = 16) is a popular flowering species in the Balsaminaceae family. In order to investigate the effects of polyploidy induction in this species, shoot tip explants measuring 1.5 cm in length were treated with 0, 15, 30, and 60 μM oryzalin for 6, 12, 24, and 48 h in vitro. After conducting the flow cytometric analysis of the plantlets, it was revealed that 68.75% of the explants treated with 60 μM oryzalin for 24 h became tetraploid (2n = 4x = 32), indicating that this treatment is the most effective for tetraploidy induction. The tetraploid plants exhibited increased leaf area, leaf thickness, ovary width, pollen cell length, and stomatal size, as well as a greater number of chloroplasts within stomatal guard cells. Furthermore, tetraploid plants showed decreases in plant height, stomatal guard cell density, and number of flowers. Epidermal conical cells were enlarged by about 1.7 times in tetraploid flowers. Optical examination of petals revealed that reflection of light from the tetraploid petals was reduced among almost all spectra. Reflection was reduced in the spectral region between 350 and 400 nm, which may have occurred as a result of changes in size of the epidermal conical cells. Furthermore, the petals in the tetraploid flowers had more total anthocyanin content. The latter two observations may explain the deepening of color in tetraploid petals. The new features observed in tetraploid flowers may be useful for generating new traits in classical breeding programs. It is also possible that these changes may be caused by alterations in gene expression and protein activity and can thus be examined to identify the genetic factors associated with flowering time and flower morphology in tetraploid I. walleriana. Further investigations are needed to study the interactions between tetraploid I. walleriana and pollinators. The latter can be important for understanding the evolutionary relationship between pollinators and the polyploidy process in this plants. Treating I. walleriana with oryzalin can produce tetraploid plants. Compared to their diploid counterparts, the tetraploid plants have significant differences in their vegetative and reproductive characteristics. Changes in the form and color of the flowers can be attributed to the changes in the size of the conical cells on the surface of the epidermis, along with the increase in the total anthocyanin content in petals.

Two indole chalcone derivatives as chemosensor for cyanide anions

Two bromine substituted indole chalcone derivatives were synthesized via typical condensation reaction between 2-(hydroxyl)-4-bromine acetophenone and 3-indolealdehyde (1) or N-ethyl-3-indolealdehyde (2) in good yields. Their recognition properties for cyanide anions were investigated. The results indicate that the compounds exhibit quick and obvious color and fluorescence turn-on changes to cyanide anions with color changes from yellow to red (1) or from light yellow to deep yellow (2). Mechanism studies suggest that hydrogen bonding reaction between cyanide anions and NH moiety of compound 1 occurs, which leads to the red shift of absorption spectra and the deepening of color. To compound 2, bonding mechanism is typical Michael reaction mechanism.

Effect of Green Coffee Polyphenols on Properties of Protein Hydrolysates in Model Systems

Polyphenol-amino acid interactions during food processing cause deterioration of nutritional and organoleptic quality of proteins, peptides or free amino acids. This limits the possibility to supplement food reach in proteinaceous compounds in phenolics. The aim of this study was to assess, if encapsulation of hydroxycinnamic acids (HCAs) from green coffee, using inclusion in β-cyclodextrin (β-CD), may limit HCAs-peptides interactions. Three protein hydrolysates: from egg ovalbumin (EOH), whey protein (WPH) and soy protein (WPH) were used. After interactions a higher increase of molecular mass and degradation of essential amino acids, as well as limitation of proteolytic digestion were reported, compared to the controls. The interactions with HCAs contributed to a higher radical scavenging capacity and color deepening of peptides. Inclusion of HCAs in β-CD resulted in the limitation of HCAs-peptide interactions. Supplementing of HCAs to foods in a form of inclusion complexes could be a promising solution for reducing HCAs-peptides interactions. Practical Application Functional foods are often supplemented with polyphenols and proteinaceous compounds, such as protein isolates or protein hydrolysates. The interactions that occur between them during food processing and storage could significantly decrease their nutritional and pro-health properties. Thus it could be beneficial to protect polyphenols from these disadvantages changes by encapsulation. One of the possible solutions could be nanoencapsulation of polyphenols by inclusion into β-cyclodextrin (β-CD). This possibility was confirmed for hydroxycinnamic acids from green coffee. The interactions between them and three different protein hydrolysates were limited and, as a result, disadvantageous changes of nutritional and physicochemical properties were decreased.

Contribution of phospholipids to the formation of fishy off‐odor and oxidative stability of soybean oil

The present study identified that trimethylamine (TMA) was the major source of fishy off‐odor in soybean oil, and the component of phosphatidylcholine (PC) was responsible for its formation. The existence of phosphatidylethanolamine (PE), phosphatidylinositol (PI), and phosphatidic acid (PA) in soybean oil could retard the deterioration of PC under heat treatment. Soybean phospholipids (SP) produced better results than soybean phosphatidylcholine (NPC) in inhibiting soybean oil oxidation. And soybean phospholipids stripped off phosphatidylcholine (SPSPC) turned out to be the least effective. The synergistic effect of PC and other phospholipids components in soybean oil could enhance the antioxidant ability of individual phospholipids components. The addition of SP and SPSPC could significantly deepen the color of soybean oils under heat treatment, while NPC would not result in color deepening. We come to a conclusion that PC could be an antioxidant in oil system, but more attention should be paid to the formation of TMA in its further application.Practical applications: Knowledge of the effect of phospholipids on the formation of fishy off‐odor and oxidative stability in soybean oil is important, because it has been reported by many investigators that phospholipids can be used as a kind of natural antioxidants in oil system. The information of this work can help others to apply the phospholipids in oil industry more appropriately.Soybean oil with addition of phospholipids would generate fishy off‐odor during storage, we identified that phosphatidylcholine contained in phospholipids was responsible for the formation of trimethylamine (fishy off‐odor) in soybean oil.

Effect of Steam Flash Explosion Pretreatment on Phytate Degradation of Wheat Bran

Whole wheat flour contains many nutrients which is mainly located in wheat bran, but it has a poor bioavailability because of the massive presence of antinutritional factor phytate. To improve the bioavailability, steam flash explosion (SFE) was first employed to phytate degradation in wheat bran. Five levels of steam pressure (0.5, 1.0, 1.5, 2.0, and 2.5 MPa) and six levels of residence time (30, 60, 90, 120, 150, and 180 s) were used to investigate the phytate and color changes of wheat bran treated by SFE. The optimum process was determined at steam pressure of 2.5 MPa and residence time of 60 s. Under this process, the satisfactory phytate degradation (around 87 %) could be obtained, whereas the degree of color deepening of treated wheat bran is proportional to the phytate degradation. Observation of scanning electron microscopy (SEM) revealed that the structure of wheat bran was completely destroyed by SFE. This destruction causes the phytate to be exposed to high temperature and high pressure and consequently degraded. High-performance liquid chromatography (HPLC) results indicated that SFE could effectively change phytate into low inositol phosphate salts. As shown in the Fourier transform infrared (FT-IR) spectroscopy analysis, this change was attributed to the decomposition of phytate by interrupting the P–O–C group. Overall, phytate degradation in wheat bran during SFE attributed to the interaction of high pressure, high temperature, and acid hydrolysis.

Changes in properties of food proteins after interaction with free and β-cyclodextrin encapsulated hydroxycinnamic acids

Polyphenol–protein interactions during food processing may cause deterioration in protein nutritional quality status. This limits the possibility to enrich foods in phenolic preparations. The aim of this study was to assess whether encapsulation of hydroxycinnamic acids (HCAs) from green coffee extract (GCE) [using inclusion in β-cyclodextrin (β-CD)] limits polyphenol–protein interactions. Three different protein isolates: egg white proteins, whey protein concentrate and soy protein isolate were exposed to interact with HCAs from GCE. After interactions, a higher increase in molecular mass and higher degradation of essential amino acids, as well as limitation of proteolytic digestion and solubility of proteins were reported, compared with the controls processed without HCAs. On the other hand, the interactions contributed to a higher radical-scavenging capacity in DPPH˙ and OH˙ assays and color deepening of proteins during processing. Inclusion of HCAs in β-CD cavity resulted in the limitation of the protein–HCA interactions, thus decreased the changes in nutritional and physicochemical properties. Adding HCAs in the form of inclusion complexes could be a promising solution for reducing unfavorable protein–polyphenol interactions during processing of foods enriched with phenolic acids.

Spectrophotometric Study on Kinetics of Solvatochromism of Methyl Violet in Aqueous Methanol

AbstractThe kinetics of the reaction of methyl violet with iodide in aqueous methanol system was studied by spectrophotometric method. The rate of reaction of methyl violet in different alcoholic composition in presence of potassium iodide was observed at pH 4 and 6 at various temperatures (298–318 K). Solvatochromic effect was studied in different percentages of methanol (0–50%). Bathochromic shift was observed with the decrease in polarity of solvent. The color change was attributed to molecule's structure, the delocalization of unit electrical charge causes deepening of color and decrease of delocalization causes fading of color due to reduction of dye. Increase in the rate of reaction was observed with increase in alcoholic content and also affected by potassium iodide salt and increased with increase in concentration of potassium iodide. Energy of activation (Ea) and transition energy (ET) were calculated with the help of kinetic data. Thermodynamic parameters such as enthalpy change of activation (ΔH*), Gibbs free energy change of activation (ΔG*) and entropy change of activation (ΔS*) were evaluated as a function of concentration of solvent and salt.

Impact of compression pressure on tablet appearance

The color of model tablets deepened and tablet gloss increased with increase in compression pressure regardless of colorant type. The possible reasons for these phenomena were examined. These observations could not be explained either by polymorphic transition of the colorant or by condensation of the colorant during compression. Instead, a change in surface roughness was assumed to be the most likely reason. The increase in compression pressure made the tablet surface smoother. With the increase in the surface smoothness, diffuse reflection decreased while specular reflection increased, indicating the opposite relation between diffuse and specular reflection as a function of surface roughness. A decrease in diffuse reflection results in a deepening of color. In contrast, an increase in specular reflection causes an increase in glossiness. Thus, the surface roughness seemed to govern gloss and color. The compression pressure seems to be one of the most important factors to control tablet appearance.

Characteristics and optical spectra of U:CaF 2 crystal grown by TGT

Transparent and integral U:CaF 2 single crystals with diameters 75 mm were grown by temperature gradient technique. Distribution of uranium in the 0.3 wt% doped CaF 2 crystal was determined by inductively coupled plasma-mass spectrometry. For the first time, the segregation coefficient of U in U:CaF 2 crystal was calculated, which is equal to 0.53 depending on either the formula, K 0= C s/ C l or the general distribution equation, C s= K 0 C 0(1- g) K0−1 . The solute-enriched strips parallel to growth direction were observed under optical microscopy. The color of U:CaF 2 crystal is almost all red but for 5-mm-thickness periphery which is yellow. From the crystal growth initiating part to the finishing, the shape of absorption spectrum of red crystal does not change, but the density of all peaks gradually increases with color deepening. The red crystal mostly contains U 3+, while the yellow contains more U 2+ ions according to the comparison of optical absorption spectra.

Micro-Surface Roughening of Paper by Sputter Etching and its Optical Application

Pulp fibers were dyed with direct dye in red and then the sheet was etched by sputtering. Change in color of the sheet was investigated in terms of differential metric lightness (ΔL*), differential metric chroma (ΔC*ab) and differential metric hue (ΔH*ab) parameters on the basis of CIE L*a*b* color system. All theses parameters relating to the color depth were changed with the sputtering conditions, especially gas pressure and sputtering energy. Sputtering at a gas pressure of 10 Pa gave a maximum color deepening up to ΔL* of -1 and ΔC*ab of +3 atthe sputtering energy of 20 J/cm2 with little change of ΔH*ab, which may be the best sputtering condition for color deepening. Sputtering at the gas pressure of 1 or 0.2 Pa showed the increase in minus ΔL* and plus ΔH*ab with an increase in sputtering energy, and gave maximum plus value in ΔC*ab around the sputtering energy of 100J/cm2. Color deepening by sputtering on chromatic -colored paper is attributed to the minus ΔL* and plus ΔC*ab, both of which were occurred simultaneously. The change, of color deepening with an increase in sputtering energy as shown in the colorimetric parameters were interpretted as a combination of color deepening and anti-color deepening occurred concurrently by sputtering. The former should be caused by the surface microstructure i. e. dense forests of cones or numerous microcraters and their prestructure, and the latter should be caused by thermal degradation of fiber and dye and by the etching of fiber surface layer which has an abundance of color dye.