Red Pigment Research Articles

The Synthesis of Fe2O3 from Domestic Waste as a Multipurpose Material

<p>Indonesia is categorized as an industrial country that produces a lot of metal waste, so it is necessary to process this metal waste. One way of processing metal waste is that it can be used as pigment. Pigments are natural substances that give rise to color, namely optical properties whose applications are endless, almost all industrial fields really need pigments, from the ceramics industry, paint industry, and plastics industry to batik craftsmen who also need pigments or dyes. The method used in this test is hydrometallurgy, which consists of a leaching process and recovery. In this research, the pigment was produced oxide red from iron wool raw materials. The weight of the oxide red pigment obtained for Experiment 1: 0.20 grams, Experiment 2: 4.96 grams, Experiment 3: 2.63 grams, Experiment 4: 2.22 grams. Then the yield obtained in Experiment 1: 0.204 grams of pigment/gram of iron, Experiment 2: 1.984 grams of pigment/gram of iron, Experiment 3: 1.052 grams of pigment/gram of iron, and Experiment 4: 0.888 grams of pigment/gram of iron. The conversion obtained in Experiment 1: 60%, Experiment 2: 74%, Experiment 3: 81% and Experiment 4: 78%. The pigment results obtained using this method can be further applied in industry because the conversion results obtained are quite high.</p>

The effect of purple sweet potato flour (Ipomoea batatas L) as substitution on anthocyanins content and antioxidant capacity of snow white’s ball cookies

This research investigates the impact of substituting wheat flour againts purple sweet potato flour (Ipomoea batatas L.) on the anthocyanins content and antioxidant capacity of Snow White’s Ball Cookies. Anthocyanins are natural vibrant red, purple, and blue pigments contained in many foods; including purple sweet potato. Anthocyanins are part of a larger group of compounds called flavonoids, which have antioxidant properties and are associated with several potential health benefits. Antioxidants are known for their role in mitigating oxidative stress and promoting health. Purple sweet potatoes are esteemed for their rich antioxidant content, primarily attributed to the presence of anthocyanins. This study aims to determine whether including purple sweet potato flour (PSPF) enhances the antioxidant properties of these cookies. The method used in this study is a completely randomized design experiment (CRD). There are four treatments: substitution of 25%, 50%, 75%, and 100%. The results of this study indicate that 100% (Formula E) substitution of purple sweet potato flour has the lowest antioxidant capacity of 85.04 ppm and higher anthocyanins content of 5.30 (mg/100g). So, it is proven that the antioxidant content in the form of anthocyanins in snow white ball cookies is high.

Weathering resistance of plant fiber‐reinforced high‐density polyethylene matrix composites: Effect of different pigments

AbstractThe effects of iron oxide red pigment, organic red 254 pigment, titanium white pigment, and carbon black pigment on the properties of wood fiber (WF)reinforced high‐density polyethylene (HDPE) composites under outdoor aging conditions were investigated. The results indicate the addition of pigments in the outdoor aging process has a certain physical protection effect on the composites, effectively preventing the damage of ultraviolet rays on the WF/HDPE composites, and the mechanical experiments show that the pigments protect the composites more obviously in the first 3 months. Among them, the carbon black pigment had the best color‐fixing effect on the composites, with the ∆E* value is only 4.1, and the protective effect on the composites was relatively good due to its special structure. The quality change also verified again that the carbon black pigment has a certain protective effect on the plant fiber composites in the pre‐aging period outdoors, in which the mass of the composites with added carbon black pigment increased by 0.14%. Comprehensively, it shows that the addition of pigment cannot completely prevent the photo‐oxidation reaction of the composites from occurring, but it can effectively slow down the aging process of the composites and prolong the service life.Highlights WF/HDPE‐modified composites were prepared by injection molding. The surface color of composites with pigment additions was analyzed. The addition of pigments effectively protects the composites. Mechanical and thermal properties have also been investigated.

Skin color of Chinese women across different regions of China: An analysis based on both individual typology angle and hue angle

Skin color is considered an important beauty standard for women in China. The typical tool for skin color measurement, individual typology angle (ITA), was developed based on Caucasian skin features. The ITA effectively measures the brightness of facial skin, which is traditionally associated with beauty in Caucasian women. However, in Chinese women, whiteness is not the only determinant of skin esthetics, and other elements such as “yellowness” and “redness” are also important considerations. Thus, the hue angle system was developed based on the skin features of Chinese women, whose skin is typically on the “yellow-red” spectrum. Studies examining the skin color of Chinese women based on both the ITA and hue angle should be carried out. The skin colors of 4500 women aged 18–45 years across five different regions of China were measured using both the ITA and hue angle systems. The relationship of the “red pigment and melanin content” with the “brightness and redness of skin color” was also examined. Further, the different skin types of women across different regions were identified. Measurements based on the ITA system reveal a saddle-shaped distribution of skin brightness among Chinese women across five different regions, with skin brightness being high in the east-west regions and low in the north-south regions. The ITA and hab values are not consistent in individual women, and thus, both need to be considered when evaluating skin color. Additionally, no correlation between the skin’s red pigment and melanin content and the skin’s ITA and hab values is identified. This study provides skin color data based on both the ITA and hue angle systems. The findings show that skin ITA/hab values cannot simply be explained by the red pigment/melanin content of the skin. Given the distribution of skin types across different regions of China, whitening ingredients causing little to no irritation should be used to formulate whitening cosmetics.

Prodigiosin Inhibits Transforming Growth Factor β Signaling by Interfering Receptor Recycling and Subcellular Translocation in Epithelial Cells.

Prodigiosin (PG) is a naturally occurring polypyrrole red pigment produced by numerous microorganisms including some Serratia and Streptomyces strains. PG has exhibited promising anticancer activity; however, the molecular mechanisms of action of PG on malignant cells remain ambiguous. Transforming growth factor-β (TGF-β) is a multifunctional cytokine that governs a wide array of cellular processes in development and tissue homeostasis. Malfunctions of TGF-β signaling are associated with numerous human cancers. Emerging evidence underscores the significance of internalized TGF-β receptors and their intracellular trafficking in initiating signaling cascades. In this study, we identified PG as a potent inhibitor of the TGF-β pathway. PG blocked TGF-β signaling by targeting multiple sites of this pathway, including facilitating the sequestering of TGF-β receptors in the cytoplasm by impeding the recycling of type II TGF-β receptors to the cell surface. Additionally, PG prompts a reduction in the abundance of receptors on the cell surface through the disruption of the receptor glycosylation. In human Caucasian lung carcinoma cells and human hepatocellular cancer cell line cells, nanomolar concentrations of PG substantially diminish TGF-β-triggered phosphorylation of Smad2 protein. This attenuation is further reflected in the suppression of downstream target gene expression, including those encoding fibronectin, plasminogen activator inhibitor-1, and N-cadherin. SIGNIFICANCE STATEMENT: Prodigiosin (PG) emerges from this study as a potent TGF-β pathway inhibitor, disrupting receptor trafficking and glycosylation and reducing TGF-β signaling and downstream gene expression. These findings not only shed light on PG's potential therapeutic role but also present a captivating avenue towards future anti-TGF-β strategies.

Bacillus sp. G2112 Detoxifies Phenazine-1-carboxylic Acid by N5 Glucosylation.

Microbial symbionts of plants constitute promising sources of biocontrol organisms to fight plant pathogens. Bacillus sp. G2112 and Pseudomonas sp. G124 isolated from cucumber (Cucumis sativus) leaves inhibited the plant pathogens Erwinia and Fusarium. When Bacillus sp. G2112 and Pseudomonas sp. G124 were co-cultivated, a red halo appeared around Bacillus sp. G2112 colonies. Metabolite profiling using liquid chromatography coupled to UV and mass spectrometry revealed that the antibiotic phenazine-1-carboxylic acid (PCA) released by Pseudomonas sp. G124 was transformed by Bacillus sp. G2112 to red pigments. In the presence of PCA (>40 µg/mL), Bacillus sp. G2112 could not grow. However, already-grown Bacillus sp. G2112 (OD600 > 1.0) survived PCA treatment, converting it to red pigments. These pigments were purified by reverse-phase chromatography, and identified by high-resolution mass spectrometry, NMR, and chemical degradation as unprecedented 5N-glucosylated phenazine derivatives: 7-imino-5N-(1'β-D-glucopyranosyl)-5,7-dihydrophenazine-1-carboxylic acid and 3-imino-5N-(1'β-D-glucopyranosyl)-3,5-dihydrophenazine-1-carboxylic acid. 3-imino-5N-(1'β-D-glucopyranosyl)-3,5-dihydrophenazine-1-carboxylic acid did not inhibit Bacillus sp. G2112, proving that the observed modification constitutes a resistance mechanism. The coexistence of microorganisms-especially under natural/field conditions-calls for such adaptations, such as PCA inactivation, but these can weaken the potential of the producing organism against pathogens and should be considered during the development of biocontrol strategies.

Extraction of organic pigments from tomato (Solanum lycopersicum L.), turmeric (Curcuma longa L.) and red amaranth (Amaranthus tricolor L.) for safe use in agro-products

The utilization of synthetic dyes in food industries is a great concern for food safety and health issues. So, natural pigments can be an excellent substitute for synthetic dyes and also health-friendly for consumers. In the experiment, natural pigments were extracted from tomato (Solanum lycopersicum L.), turmeric (Curcuma longa L.) and red amaranth (Amaranthus tricolor L.). Then the stability and consumer acceptance of the extracted pigments were examined. The highest amount of pigment was extracted from turmeric (2.14 ± 0.30 %) with ethanol solvent, followed by tomato (0.67 ± 0.06 %) with hexane: acetone (1:1) solvent, and red amaranth (0.78 ± 0.05 %) with acetone solvent. Turmeric pigment showed the highest stability in high temperatures and light exposure. All of the pigments were highly stable in a neutral environment; however, tomato pigment showed the highest stability index (84.33 ± 2.52) at pH 3.0, but turmeric pigment showed the highest stability (91.67 ± 1.53) at pH 5.0. The simple preference test revealed that the use of turmeric pigment in boiled rice had the highest acceptance rate, and in terms of taste and flavor, red amaranth pigments in ice cream. So turmeric pigment can be utilized in high-temperature processing and/or acidic foods, but tomato and red amaranth pigments might be in low-temperature processing foods such as the ice-cream and soft drinks processing industry.

Isolation and Identification of Pigment-Producing Endophytic Fungi from the Amazonian Species Fridericia chica.

Pigments of fungal origin have aroused increasing interest in the food dye and cosmetic industries since the global demand for natural dyes has grown. Endophytic microorganisms are a source of bioactive compounds, and Amazonian plant species can harbor fungi with a wide range of biotechnological applications. Popularly known in Brazil as crajiru, Fridericia chica is a medicinal plant that produces a red pigment. In this study, a total of 121 fungi were isolated in potato dextrose agar from three plants. We identified nine pigment-producing endophytic fungi isolated from branches and leaves of F. chica. The isolates that showed pigment production in solid media were molecularly identified via multilocus analysis as Aspergillus welwitschiae, A. sydowii, Curvularia sp., Diaporthe cerradensis (two strains), Hypoxylon investiens, Neoscytalidium sp. (two strains) and Penicillium rubens. These isolates were subjected to submerged fermentation in two culture media to obtain metabolic extracts. The extracts obtained were analyzed in terms of their absorbance between 400 and 700 nm. The pigmented extract produced by H. investiens in medium containing yeast extract showed maximum absorbance in the red absorption range (UA700 = 0.550) and significant antioxidant and antimicrobial activity. This isolate can thus be considered a new source of extracellular pigment.

An investigation of the photostability of 19th century artists’ cochineal lake pigments using MFT and conventional accelerated ageing tests

ABSTRACT Red lake pigments are known for their high light-sensitivity generally when exposed to museum environments. In the cultural heritage field, the colour loss experienced by organic pigments is of special concern as the appearance of objects may be significantly altered after uncontrolled exposure to light. The present work focuses on the use of microfading testing (MFT) to study the light sensitivity of 19th century cochineal paints. MFT is a technique that combines visible reflectance spectroscopy with accelerated light ageing testing and was developed to perform in situ investigations of the light-sensitivity of cultural heritage materials in a relatively short amount of time. Reconstructions of these pigments following the manufacturing processes used by 19th century Winsor & Newton workers, as well as historic samples of cochineal pigments, were prepared using gum arabic and poly(vinylacetate). Purple cochineal paints showed a moderate sensitivity to light, while Carmine, Crimson and Scarlet paints were classified as high-sensitive materials. Overall, the carmine references turned out to be the most lightfast when mixed with gum-arabic while the scarlet pigment with poly(vinyl acetate) showed a slightly smaller colour change when compared with the almost complete loss of colour of the other poly(vinyl acetate) paints. Finally, advantages and drawbacks of the MFT method are addressed.

Identification of a novel monocyclic carotenoid and prediction of its biosynthetic genes in Algoriphagus sp. oki45

Bacteria belonging to the genus Algoriphagus have been isolated from various sources, such as Antarctic sea ice, seawater, and sediment, and some strains are known to produce orange to red pigments. However, the pigment composition and biosynthetic genes have not been fully elucidated. A new red-pigmented Algoriphagus sp. strain, oki45, was isolated from the surface of seaweed collected from Senaga-Jima Island, Okinawa, Japan. Genome comparison revealed oki45’s average nucleotide identity of less than 95% to its closely related species, Algoriphagus confluentis NBRC 111222 T and Algoriphagus taiwanensis JCM 19755 T. Comprehensive chemical analyses of oki45’s pigments, including 1H and 13C nuclear magnetic resonance and circular dichroism spectroscopy, revealed that the pigments were mixtures of monocyclic carotenoids, (3S)-flexixanthin ((3S)-3,1′-dihydroxy-3′,4′-didehydro-1′,2′-dihydro-β,ψ-caroten-4-one) and (2R,3S)-2-hydroxyflexixanthin ((2R,3S)-2,3,1′-trihydroxy-3′,4′-didehydro-1′,2′-dihydro-β,ψ-caroten-4-one); in particular, the latter compound was new and not previously reported. Both monocyclic carotenoids were also found in A. confluentis NBRC 111222 T and A. taiwanensis JCM 19755 T. Further genome comparisons of carotenoid biosynthetic genes revealed the presence of eight genes (crtE, crtB, crtI, cruF, crtD, crtYcd, crtW, and crtZ) for flexixanthin biosynthesis. In addition, a crtG homolog gene encoding 2,2ʹ-β-hydroxylase was found in the genome of the strains oki45, A. confluentis NBRC 111222 T, and A. taiwanensis JCM 19755 T, suggesting that the gene is involved in 2-hydroxyflexixanthin synthesis via 2-hydroxylation of flexixanthin. These findings expand our knowledge of monocyclic carotenoid biosynthesis in Algoriphagus bacteria.Key points• Algoriphagus sp. strain oki45 was isolated from seaweed collected in Okinawa, Japan.• A novel monocyclic carotenoid 2-hydroxyflexixanthin was identified from strain oki45.• Nine genes for 2-hydroxyflexixanthin biosynthesis were found in strain oki45 genome.Graphical

Tamyb10-D1 restores red grain color and increases grain dormancy via suppressing expression of TaLTP2.128, non-specific lipid transfer protein in wheat

Grain dormancy of wheat is closely associated with grain color: red-grained lines show higher dormancy than white-grained lines. The production of red pigments is regulated by R-1, Tamyb10 gene. However, the relation between grain color and dormancy remains unknown. For this study, we generated transgenic lines which were introduced a DNA fragment containing Tamyb10-D1 gene and its a 2 kb promoter including the 5′ untranslated region into white-grained wheat. Transgenic lines showed red-grained and higher dormant traits. Contents of plant hormones and gene expression of embryos at 30 days after pollination were examined in a wild type and a transgenic line. No differences were observed in the contents of plant hormones, but several genes are differentially expressed between these lines. One differentially expressed gene, TaLTP2.128, is a member of non-specific lipid transfer proteins. It was expressed higher in white grains than in red grains. A putative amino acid sequence showed similarity to that of OsHyPRP5, which is identified as QTL controlling low-temperature germinability in rice. Expression of TaLTP2.128 was increased by grain imbibition. The increasing levels were higher not only in other white-grained lines, but also in non-dormant red-grained lines. TaLTP2.128 was expressed at a quite early stage of germination. These study findings indicate that Tamyb10 regulates dormancy release by the modification of TaLTP2.128 acting as trigger of germination.

Differences in the Chromogenic Effect of Corn Starch and Potato Starch on Paprika Red Pigment and Structural Characterisation.

The present study aims to investigate the chromogenic effect and the interaction between starch-pigment complexes of corn starch (CS) and potato starch (PS) complexed with paprika red pigment. Compared to PS, CS showed 12.5 times higher adsorption capacity for paprika red pigment. Additionally, the a* value of CS-P (26.90 ± 0.23) was significantly higher than that of PS-P (22.45 ± 1.84), resulting in a corn starch-paprika red pigment complex (CS-P) with a more intense red colour. The addition of paprika red pigment significantly decreased the particle size and porosity of CS by 48.14 ± 5.29% and 17.01 ± 3.80%, respectively. Conversely, no significant impact on PS was observed. Additionally, the Fourier transform infrared (FT-IR) spectroscopy results revealed that the starch molecules and paprika red pigment were bound to each other through strong hydrogen bonds. X-diffraction (XRD) results indicated that the starch-paprika red pigment complexes have a V-shaped structure. Furthermore, the relative crystallinity of the complexes between starch and red pepper pigment showed an increasing trend, however, the relative crystallinity of CS increased significantly by 11.77 ± 0.99-49.21 ± 3.67%. Consequently, the CS-P colouring was good.

Photodynamic Therapy With Resveratrol and an Nd:YAG Laser for Enterococcus faecalis Elimination.

Enterococcus faecalis is the leading cause of endodontic treatment failures. Despite various conventional disinfection approaches, microorganisms often persist in root canals. Photodynamic therapy (PDT) is an adjunct antimicrobial strategy employing a nontoxic photosensitizer (PS) and light source. This study evaluated the antimicrobial effect of PDT using an Nd:YAG laser and resveratrol (RSV) with or without pigment, and confirmed that RSV is nontoxic as a PS. We employed laser irradiation at a 3W output power, using RSV and red pigment as the PS, on an E. faecalis bacterial solution. Subsequently, colony-forming units were quantified. The impact of RSV on osteoblasts was measured using an MTT assay. E. faecalis counts declined after laser irradiation. The combined application of laser irradiation with RSV, red pigment, or both showed a reduction compared to no irradiation and control groups without RSV and red pigment. The 50% cytotoxic concentration against osteoblast cells from mice incubated with RSV for 48 h was 162 μM. The value with RSV and laser was 201 μM and that with RSV and red pigment was 199 μM. The value with RSV, laser and red pigment was 357 μM. The combination of Nd:YAG laser irradiation and RSV as the PS with pigment was efficacious for E. faecalis elimination without inducing any toxic effects on osteoblasts. This combination holds potential as a root canal irrigation strategy.

Sustainable reutilization of ion-adsorbed rare earth tailings: Preparation of low-cost functionalized pigments

In order to alleviate the ecological pressure caused by rare earth tailings, this study focuses on the application of ion-adsorbed rare earth tailings in the preparation of functional pigments. By using mechanical grinding and high-temperature calcination, 33 new functionalized red pigments were successfully prepared by doping iron and lanthanum elements. X-ray diffraction (XRD), scanning electron microscopy (SEM), CIE 1976 color space system, and ultraviolet–visible–near-infrared spectrophotometer were used for characterization. The synthesized pigment exhibits a rich color range from light yellow to reddish brown. Compared with commercially available iron red pigments, it exhibits significantly enhanced near-infrared reflectance, excellent acid and alkali resistance, and strong thermal stability up to 900 °C. It is worth noting that pigment P-1-2-1 achieved the best red value (L* = 43.73, a* = +24.07, b* = +15.65) with a maximum near-infrared reflectance of 91 %. Therefore, the utilization of rare earth tailings as raw materials for the preparation of functional pigments has significant effects. This study provides valuable insights for the development of eco-friendly pigments, which not only helps alleviate the urban heat island effect but also promotes the sustainable utilization of rare earth tailing resources, contributing to the achievement of carbon neutrality goals.

Surface roughness of pigmented and non-pigmented maxillofacial silicone elastomer before and after artificial aging

Maxillofacial prostheses are frequently made from silicone elastomer. The silicone material’s rough surface can lead to the accumulation of microorganisms, irritation of the surrounding soft tissue, and the progression of some microsites into mechanical failure and color deterioration. This in vitro study aimed to compare the surface roughness of M511 heat-vulcanized maxillofacial silicone before and after artificial aging. Eighty disk-shaped specimens were prepared and divided equally among five experimental groups based on pigmentation, with 16 samples in each group. The colorless specimens were prepared without adding any pigment. The four study groups were prepared using distinct pigments (red, blue, yellow, and their mixture). Half of the specimens in each group were tested before aging, while the other half was tested after 750 h of artificial aging. Surface roughness was measured using atomic force microscopy (AFM), and the silicone bonds and pigments were observed using Fourier transform infrared spectroscopy-attenuated total reflectance (FTIR-ATR). Data were compared between groups using a two-way analysis of variance, independent sample t-test, and Tukey’s post hoc test, considering a p < 0.05 statistically significant. FTIR-ATR showed no differences between the pre-and post-aging groups, with similar peaks observed. The surface roughness significantly increased in the colorless, blue, and mixed pigment groups (p < 0.001), surface roughness increased by 155.66%, 14.83%, and 96.12% respectively for colorless, blue pigment, and the mixture of pigments after 750 h of artificial aging. In contrast, the surface roughness significantly decreased in the yellow pigment (90.98%) and red pigment (5.7%) (p ≤ 0.001) after aging. The yellow pigment showed the smoothest surface after aging, while colorless specimens showed the roughest surface. Two-way ANOVA showed that pigment type and aging time significantly affected surface roughness. Therefore, induced aging considerably impacted the surface topography of maxillofacial silicone. The pigment type and distribution in the silicone matrix affected its surface roughness. The AFM analysis is a simple and straightforward method for assessing surface roughness at the nanometer level.

Initial investigations of rubricated inscriptions from Roman Sicily: Comparing the material evidence with ancient writers’ ideals

Although the polychromy of ancient statuary has become a regular topic in archaeological discussions, in part thanks to archaeometrical analyses, little attention has been given to such aspects in the field of epigraphy. The aim of this paper is to identify analytically the red pigments employed in inscriptions from southeastern Sicily in the Roman period (1st-6th c. CE), and to investigate the relationship between actual material practice and ancient terminology. Minimally invasive identification of cinnabar (mercuric sulphide) on some funerary and honorific inscriptions aligns with Pliny’s statement on the use of “minium”. However, other less expensive lead-containing pigments were detected, suggesting that different materials were used in different contexts and according to various practices. It appears from this preliminary study that choices of ancient red pigments can provide additional information for understanding epigraphic cultures.

Physico-Chemical and Sensory Assessment of Local and Imported Catfish Fillets

In this study, twenty fresh African catfish (Clarias gariepinus) and silver catfish (Bagrus bayad) fillets as well as twenty frozen pangasius catfish (Pangasianodon hypophthalmus) fillets were collected from Egyptian local markets and retailers during 2021. Pangasius catfish fillets can be divided into two grades: white basa fillets (grade I, white colour) and red basa fillets (grade II, pale pink to red colour). This study aimed to assess the physical (colour and shear force), chemical (pH, TVB-N and TBARS) and sensory parameters of catfish fillet samples. The sensory attributes of raw catfish fillets were measured using a 9-point hedonic scale and these attributes include colour and appearance, odor, texture, and overall acceptability. The results of the proximate composition showed that the African catfish and silver catfish fillets had significantly lower moisture (76.12-76.94) and higher crude protein (17.19-17.24) and fat levels (3.35-4.12) compared to the frozen Pangasius catfish fillets. The total volatile basic nitrogen (TVB-N) ranged from 6.83 to 16.38 mg/100g, thiobarbituric acid-reactive substances (TBARS) values ranged from 0.35 to 1.01 mg malonaldehyde/kg and pH ranged from 6.43 to 7.35. The TVB-N and TBARS values of examined catfish fillets were within acceptable limits. The African catfish fillets were darker and characterized by higher redness (a*) and lower yellowness (b*) values as well as higher shear force values (9.52 kgf/m3), while white basa fillet was the lowest darkness, less saturated with the red pigment (a*) and more saturated with the yellow component (b*) as well as lower shear values (2.17 kgf/m3) among the examined catfish fillets. African catfish and silver catfish fillets showed significantly higher sensory scores than the Pangasius catfish fillets. All the organoleptic properties of raw catfish fillets were above the rejection threshold score (≤4.0) In conclusion, catfish fillets were of superior quality and acceptable for human consumption.

The Effect of Corn Cob Size as a Substrate and Fermentation Time on Carotenoid Production by Neurospora sitophila

Natural pigments are recommended to reduce the use of synthetic pigments, one of which is the primary color yellow. Carotenoids are natural yellow to red pigments that are produced naturally by plants and microorganisms. Fermentation of carotenoids by the microorganism Neurospora sitophila is one solution to the challenges of plant based pigment which compete with the needs of food, land, and dependence on weather and seasons. Corn cobs are one of the cellulotic wastes that can be used as a carbon source. This research aims to examine the effect of corn cob size (60, 20, 8 mesh) and fermentation time (3, 6, 9 days) on the carotenoid pigments produced. The spectrophotometer analysis show that fermentation increase the initial carotenoids concentration in corn cobs. The smaller the substrate and the longer fermentation time, the greater the concentration of carotenoids produced. The highest concentration was obtained on 60 mesh substrate with 9 days fermentation at 31.79 ppm. FTIR analysis shows the presence of carotenoid pigments by the C=C and C-H, and the O-H functional group which represent zeaxanthin, astaxanthin and neurosporaxanthin compounds. Based on SEM test results, the average particle size of corn cob powder was 50 μm with porosity of 67.93%.

Identification and quantification of pigments in plant leaves using thin layer chromatography-Raman spectroscopy (TLC-Raman).

Carotenoids are yellow, orange, and red pigments commonly found in plants. In leaves, these molecules are essential for photosynthesis, but they also play a major role in plant growth and development. Efficiently monitoring concentrations of specific carotenoids in plant tissues could help to explain plant responses to environmental stressors, infection and disease, fertilization, and other conditions. Previously, Raman methods have been used to demonstrate a correlation between plant fitness and the carotenoid content of leaves. Due to solvatochromatic effects and structural similarities within the carotenoid family, current Raman spectroscopy techniques struggle to assign signals to specific carotenoids with certainty, complicating the determination of amounts of individual carotenoids present in a sample. In this work, we use thin layer chromatography-Raman spectroscopy, or TLC-Raman, to identify and quantify carotenoids extracted from tomato leaves. These quick and accurate methods could be applied to study the relationship between pigment content and a number of factors affecting plant health.

Structure and morphology of red pigments based on sepiolite.

Sepiolite is an important raw fibrous material. A method to prepare red pigments based on sepiolite through the thermal treatment of sepiolite with sulfur and sodium sulfide hydrate is reported. Sepiolite was heated until 800 °C in order to remove zeolitic water, the first coordinated water, the second coordinated water, and structural hydroxyls. Several [S/Na2S]molar ratios in the range 0.5-7 were employed. The properties of these pigments were studied by different analytical techniques, such as colorimetric analysis, thermal analysis, Fourier transform infrared (FTIR) spectroscopy, X-ray diffraction and scanning electron microscopy. The samples with [S/Na2S] = 0.5 and 1, corresponding to high contents of sodium sulfide in the synthesis procedure, exhibit high values of the colorimetric parameter CIE a* and a maximum reflectance in the visible zone belonging to red, based on the red colour of the samples. Under the reducing conditions of the synthesis, sulfur forms polysulfides of the general formula [Sx]2-. The sodium sulfide reacts with the excess S to form polysulfides as well. From the polysulfides, the radical anions of the general formula [Sx/2]˙- originate and they are identified as the chromophore groups responsible for the color in the sulfur-based pigment analogues of ultramarines. The red colour of the samples could be mainly attributed to the presence of S4 and S4˙- identified by FTIR.