Development of a Sensitive Colorimetric Indicator for Detecting Beef Spoilage in Smart Packaging.

This study aimed to fabricate and characterize a novel colorimetric indicator designed to detect ammonia (NH3) and monitor meat freshness. The sensing platform was constructed using electrospun nanofibers made from polylactic acid (PLA), which were then impregnated with anthocyanins as a natural pH-sensitive dye, extracted from red cabbage. This research involved investigating the relationship between the various concentrations of anthocyanins and the colorimetric platform's efficiency when exposed to ammonia vapor. Scanning electron microscope (SEM) results were used to examine the morphology and structure of the nanofiber mats before and after the dip-coating process. The study also delved into the selectivity of the indicator when exposed to various volatile organic compounds (VOCs) and their stability under extreme humidity levels. Furthermore, the platform's sensitivity was evaluated as it encountered ammonia (NH3) in concentrations ranging from 1 to 100 ppm, with varying dye concentrations. The developed indicator demonstrated an exceptional detection limit of 1 ppm of MH3 within just 30 min, making it highly sensitive to subtle changes in gas concentration. The indicator proved effective in assessing meat freshness by detecting spoilage levels in beef over time. It reliably identified spoilage after 10 h and 7 days, corresponding to bacterial growth thresholds (107 CFU/mL), both at room temperature and in refrigerated environments, respectively. With its simple visual detection mechanism, the platform offered a straightforward and user-friendly solution for consumers and industry professionals alike to monitor packaged beef freshness, enhancing food safety and quality assurance.

Highly Efficient DSSCs Sensitized Using NIR Responsive Bacteriopheophytine-a and Its Derivatives Extracted from Rhodobacter Sphaeroides Photobacteria.

Employing naturally extracted dyes and their derivatives as photosensitizers towards the construction of dye-sensitized solar cells (DSSCs) has been recently emerging for establishing sustainable energy conversion devices. In this present work, Rhodobacter Sphaeroides Photobacteria (Rh. Sphaeroides) was used as a natural source from which Bacteriopheophytine-a (Bhcl) dye was extracted. Further, two cationic derivatives of Bhcl, viz., Guanidino-bacteriopheophorbide-a (Gua-Bhcl) and (2-aminoethyl)triphenylphosphono-bacteriopheophorbide-a (2AETPPh-Bhcl) were synthesized. The thus obtained Bhcl, Gua-Bhcl and 2AETPPh-Bhcl were characterized using liquid chromatography-mass spectrometry (LC-MS) and their photophysical properties were investigated using excitation and emission studies. All three near-infrared (NIR) responsive dyes were employed as natural sensitizers towards the construction of DSSC devices, using platinum as a photocathode, dye-sensitized P25-TiO2 as a photoanode and I-/I3- as an electrolyte. DSSCs fabricated using all three dyes have shown reasonably good photovoltaic performance, among which 2AETPPh-Bhcl dye has shown a relatively higher power conversion efficiency (η) of 0.38% with a short circuit photocurrent density (JSC) of 1.03 mA cm-2. This could be attributed to the dye's natural optimal light absorption in the visible and NIR region and uniform dispersion through the electrostatic interaction of the cationic derivatives on the TiO2 photoanode. Furthermore, the atomic force microscopy studies and electrochemical investigations using cyclic voltammetry, electrochemical impedance spectroscopy and Bode's plot also supported the enhancement in performance attained with 2AETPPh-Bhcl dye.

Dyeing Properties, Color Gamut, and Color Evaluation of Cotton Fabrics Dyed with Phellodendron amurense Rupr. (Amur Cork Tree Bark).

The application of plant dyes in the textile industry has been very limited due to their limited sources, incomplete color space, and narrow color gamut, etc. Therefore, studies of the color properties and color gamut of natural dyes and the corresponding dyeing processes are essential for completing the color space of natural dyes and their application. In this study, water extract from the bark of Phellodendron amurense (P. amurense) was used as a dye. Dyeing properties, color gamut, and color evaluation of dyed cotton fabrics were studied, and optimal dyeing conditions were obtained. The results showed that the optimal dyeing process was pre-mordanting with liquor ratio at 1:50, P. amurense dye concentration at 5.2 g/L, mordant concentration (aluminum potassium sulfate) at 5 g/L, dyeing temperature at 70 °C, dyeing time of 30 min, mordanting time of 15 min, and pH 5. Through the optimization of the dyeing process, a maximum color gamut range was obtained with lightness L* value from 74.33 to 91.23, a* value from -0.89 to 2.96, b* value from 4.62 to 34.08, chroma C* value from 5.49 to 34.09, and hue angle h° value from 57.35° to 91.57°. Colors from light yellow to dark yellow were obtained, among which 12 colors were identified according to the Pantone Matching Systems. The color fastness against soap-washing, rubbing, and sunlight on the dyed cotton fabrics all reached grade 3 level or above, further expanding the applicability of natural dyes.

Extraction, microencapsulation, and application of anthocyanins from juçara palm fruit (Euterpe edulis Mart.): enhancement of natural pigment.

The Juçara fruit (Euterpe edulis Martius) has been progressively standing out for presenting significant biological and nutritional activity. Its functional characteristics are related to its high content of anthocyanins, which, when isolated, are highly unstable, limiting their applications. The present research proposed to obtain an anthocyanin-rich extract from the juçara pulp, microencapsulate it with the maltodextrin and beta-cyclodextrin (beta-CD) matrices and evaluate the stability of the microencapsulated anthocyanins against light, pH, and milk development fermented. The use of encapsulating agents brought the anthocyanins significant thermal and light stability, in addition to intensifying their colors in a broader pH range. The FTIR-ATR techniques and the thermal analyzes of DSC and TGA showed that there was no molecular inclusion between the anthocyanins in the extract and beta-CD, but there was a physical interaction with the maltodextrin. In the development of fermented milk, the use of maltodextrin showed better product color stability. Therefore, anthocyanin microencapsulation processes can contribute to the development of innovative, more stable, and effective commercial food products. Supplementary Information: The online version contains supplementary material available at 10.1007/s13197-022-05623-w.

Application of Achillea millefolium extract as a reducing agent for synthesis of silver nanoparticles (AgNPs) on the cotton: antibacterial, antioxidant and dyeing studies.

The phyto-synthesis of silver nanoparticles and cotton dyeing with natural colorants can reduce the environmental impact of the process considerably. In this study, the extraction of natural colorants from Achillea millefolium petals was optimized by ultrasound technique. The AMP extract was applied for synthesis of silver nanoparticles (Ag NPs) on the cotton fabrics. The dyeing, antibacterial and antioxidant characteristics of cotton samples were investigated to optimize the process and evaluate its efficiency. The AMP extract had good substantivity towards cotton fabrics and the presence of tannic acid, as an environmentally-friendly mordant, further improved the absorption of AMP dye. The antibacterial and antioxidant activities of the dyed samples with AMP extract of were 50%and 60%, respectively. The addition of TA and Ag enhanced the antibacterial and antioxidant activities on the cotton samples to over 99%.

Organic Electronics from Nature: Computational Investigation of the Electronic and Optical Properties of the Isomers of Bixin and Norbixin Present in the Achiote Seeds.

Organic compounds have been employed in developing new green energy solutions with good cost-efficiency compromise, such as photovoltaics. The light-harvesting process in these applications is a crucial feature that still needs improvements. Here, we studied natural dyes to propose an alternative for enhancing the light-harvesting capability of photovoltaics. We performed density functional theory calculations to investigate the electronic and optical properties of the four natural dyes found in achiote seeds (Bixa orellana L.). Different DFT functionals, and basis sets, were used to calculate the electronic and optical properties of the bixin, norbixin, and their trans-isomers (molecules present in Bixa orellana L.). We observed that the planarity of the molecules and their similar extension for the conjugation pathways provide substantially delocalized wavefunctions of the frontier orbitals and similar values for their energies. Our findings also revealed a strong absorption peak in the blue region and an absorption band over the visible spectrum. These results indicate that Bixa orellana L. molecules can be good candidates for improving light-harvesting in photovoltaics.

Physicochemical Characterization, Stability and Cytotoxicity of a Blue Dye Obtained from Genipap Fruit (Genipa americana L.).

RESEARCH BACKGROUND: The current commercial scenario indicates an increase in the demand for natural dyes. Compared to synthetic dyes, natural ones have the advantage of being sustainable, making them of great interest for the food and cosmetic industries. The development of new natural dyes is necessary, as well as the carrying out of complementary research regarding the existing ones. EXPERIMENTAL APPROACH: The present study aims to characterize the physicochemical and biological characteristics of the dye obtained from dehydrated endocarp of the genipap (Genipa americana) fruit, as well as perform the relevant stability and cytotoxicity tests. The chemical characterization was performed by HPLC-MS/MS analyses. The stability studies were carried out by spectrophotometry and cytotoxicity assays using cell culture and fluorometric methods. RESULTS AND CONCLUSIONS: After dehydration and milling of the fruit endocarp, water was added to the obtained powder (in the ratio 4:1) to extract the dye. Five compounds were elucidated using HPLC-MS/MS and confirmed the presence of the geniposide as its main compound. With the X-ray diffraction and electron microscopy analysis, we characterised the obtained powder as being amorphous and of porous structure with a variable size. The thermogravimetric analysis indicated a maximum loss of 61% mass after exposure to a temperature range from 240 to 760 °C. The obtained blue dye was stable in the absence of light, at room temperature and had neutral pH. In the cytotoxicity assay, (95.0±1.3) % of viable human fibroblasts were observed after exposure to this dye. The genipap fruit can be a viable alternative to produce a natural blue dye, since it is easy to obtain and has very low toxicity in food, pharmaceutical or cosmetic products. NOVELTY AND SCIENTIFIC CONTRIBUTION: This study demonstrates for the first time the physicochemical and biological properties of a natural blue dye from G. americana fruit.

Microencapsulation of betacyanin from red dragon fruit (Hylocereus polyrhizus) peels using pectin by simple coacervation to enhance stability.

Betacyanin is a red natural dye pigment widely used in food products. However, the pigment is also unstable and easily degraded by temperature during storage and food processing. This research aims to increase the stability of betacyanin obtained from dragon fruit peels using pectin as a wall medium via the coacervation method. Due to the efficiency and shell integrity, the coacervation method was selected instead of spray drying to enhance betacyanin's stability. Coacervation was conducted in a three-necked round-bottomed flask fitted with a mercury-sealed stirrer and reflux condenser. An accelerated stability test was conducted at 80 °C and 100 °C for 30 min and considered completed after obtaining a stable absorbance. Two full factorials, three-level design, for 80 °C and 100 °C, were analyzed by Response Surface Methodology using Minitab® 19. The core/wall ratio, agitation speed, and pH were the continuous variables, with temperature as the categorical variables. The models were yielded high R-square and low coefficient of variance on the validation process. Simple coacervation is selected because of a superior method such as simplicity, low-cost, high efficiency, and high shell integrity.

Malagasy Dye Plant Species: A Promising Source of Novel Natural Colorants with Potential Applications - A Review.

Due to the potentially harmful effects of some synthetic dyes, there is an increasing demand for natural colorants. Recent literature has emphasized the necessity of investigating new sources of dyes. This review discusses the biological sources of dyes derived from the rich plant diversity of Madagascar. As one of the first contributions on the use of these dyestuffs for dyeing textiles, it provides an overview of 128 dye plant species with other potential applications for coloring materials in industry. A detailed description of the botanical and chemical properties of these dyestuffs is given. We believe that the Madagascar plant diversity may be a promising source of novel colorants not yet investigated. We considered it worthwhile to carry out a thorough scientific study of a set of Malagasy plants carefully selected for their coloring properties together with their potential use and valorization in specialized industries where use of natural colorants would be a particular interest.

A Colorimetric pH Sensor Based on Clitoria sp and Brassica sp for Monitoring of Food Spoilage Using Chromametry.

A developed colorimetric pH sensor film based on edible materials for real-time monitoring of food freshness is described. The mixed natural dyes from edible plants Clitoria sp and Brassica sp were extracted and incorporated into ι-carrageenan film as a colorimetric pH sensor film for monitoring food spoilage and its freshness. The color changes of the developed colorimetric sensor film were measured with chromametry and UV-vis spectroscopy, respectively. Experimental results show that colorimetric pH sensor film demonstrated statistically significant differences (p < 0.05) between CIE-L*a*b* coordinates color system indicated that the developed colorimetric sensor film was able to give a gradual change in color over a wide pH range. The color of the colorimetric sensor film also changes discretely and linearly with factors that contribute to food spoilage using shrimp and durian samples. Moreover, the developed colorimetric pH sensor film has the potential to be used as a safe, non-destructive testing and also a flexibly visual method for direct assessment of food freshness indicator during storage.

The liturgical cope of D. Teotónio of Braganza: material characterization of a 16th century pluviale.

A 16th century liturgical cope belonging to D. Teotónio of Braganza (collection of the Museum of Évora, ME 172/1) was selected for a material study. The cope is made of a variety of materials that include two different types of metal threads, dyed silk yarns, and vegetable yarns used in the weft. Several samples from different points representing the different metal thread types and colored silk yarns were collected. Stereomicroscopy (optical microscopy) and scanning electron microscopy were used for morphological analysis of the textile fibers and evaluation of metal thread degradation products. Evaluation of mordants and metal thread composition was carried out by energy-dispersive X-ray spectroscopy. Liquid chromatography with diode array and mass spectrometry detection was used for dye identification, which allowed the determination of three different red dye sources and one yellow dye source in the colored silk yarns. Although different fabrics were used in the manufacturing of the cope, similarities identified in the characterization of the materials suggest that a single workshop was involved in its making.

Clean synthesis of silver nanoparticles (AgNPs) on polyamide fabrics by Verbascum thapsus L. (mullein) extract: characterization, colorimetric, antibacterial, and colorfastness studies.

The production of antibacterial colored textiles using nanomaterials (NMs) has become an ideal goal from both a research and industrial perspective. In this study, the clean synthesis and characterization of silver nanoparticles (AgNPs) on polyamide fabrics were performed using mullein extract for the first time. Natural dyes were extracted from mullein leaves using an ultrasonic method, with an optimal amount of 15 g/L. The synthesized AgNPs in different ratios of mullein extract and Ag ions were analyzed (using UV-visible spectroscopy) and dynamic light scattering (DLS). It was found that AgNPs synthesized with a ratio of 1:4 of mullein extract: to Ag ions had a diameter of 85 nm. The active site groups of the synthesized AgNPs were characterized using Fourier transform infrared spectroscopy (FT-IR). Nylon fabrics dyed with different ratios of mullein extract and Ag ions exhibited acceptable color strength values (K/S) of 3.36. Furthermore, the reduction in bacterial growth for dyed fabrics improved with an increase in the ratio of Ag ions, with a 100% reduction observed for a sample dyed with mullein extract: Ag ions at a ratio of 1:4. Overall, this method offers a simple, low-cost, and compatible process with environment without the consumption of any chemicals to producing nylon with acceptable antibacterial and dyeing properties.

Enhancing cotton fabric dyeing: Optimizing Mordanting with natural dyes and citric acid.

This study investigates the optimization of fabric dyeing using natural dyes extracted from Clitoria ternatea, Cudrania javanensis, and Hibiscus sabdarifa by enhancing the mordanting process with citric acid. The principle of adding citric acid is as a crosslinker agent between cotton fabric and dye through an esterification reaction. A central composite design (CCD) of the response surface methodology (RSM) is employed to optimize parameters. Three mordanting variations and dyeing parameters, such as temperature and time, are considered. Results indicate that pre-mordanting yields superior outcomes, with optimal temperature and time at 65 °C and 82 min, respectively. Cotton fabric dyed with Cudrania javanensis and citric acid exhibits the highest color durability. This study successfully demonstrates the effectiveness of pre-mordanting, meta-mordanting, and post-mordanting methods with optimized conditions for achieving optimal coloring outcomes, particularly highlighting the efficacy of citric acid as a crosslinking agent.

Rhus coriaria L. in tradition and innovation like natural dye.

Nowadays, secondary raw materials (SRM) obtained from plant matrices are of great interest for circular economy, suitable for sustainable measures to reduce environmental impact. This work focused on the extraction, characterization and quantification of compounds obtained from leaves and fruits of the Sicilian sumac, Rhus coriaria L. and their application as natural dyes on textile fibres. Extractions were performed with Extractor Naviglio®, maceration and ultrasound assisted methods and food-grade solvents (aqueous and hydroalcoholic) to evaluate the yields for dye compounds. The presence of colouring molecules was evaluated by UV-Vis spectrophotometer, and the extracts selected for colouring were quantified and characterized by LC-MS. The results showed that Extractor Naviglio® achieved the best extraction yield, and the ethanol-water mixture extracts had a higher amount of total phenolic compounds (TPC) and a higher content of total colouring compounds (TCC). These extracts were selected for subsequent applications as dyes for linen, cotton and wool. The chemical profile of selected extracts was rich in compounds such as gallotannin and anthocyanin class. Fibre dyeing was verified by recording CIELAB colouring coordinates. The results suggest that the dyes obtained from R. coriaria can be of great interest for artisanal and industrial processes, in accordance with environmental sustainability.

Sustainable appraisal of lipstick tree seeds (Bixa orellana)-based bixin natural orange colorant for green mordanted silk fabrics and wool yarns.

This research aims to optimize the silk and wool dyeing process using natural dyes from Bixa orellana (annatto) through response surface methodology. Central composite design experiments highlight the significant enhancement of color outcomes achieved through microwave treatment. For silk, the optimal conditions (80 °C for 40 min) with annatto extract yield a color strength (K/S) of 17.8588, while wool achieves a K/S of 7.5329. Introducing eco-friendly bio-mordants, such as pomegranate peel and red sumac tannins, enhances color strength. Pre-dyeing treatments with 2% red sumac, 1.5% pomegranate peel, and weld flower extracts for silk produce high color strength, with K/S values of 16.4063, 16.3784, and 12.1658, respectively. Post-dyeing, the K/S values increase to 40.1178, 17.4779, and 21.6494. Wool yarn exhibits similar improvements, with pre-dyeing K/S values of 13.1353, 13.5060, and 16.3232, escalating to 10.5892, 15.3141, and 23.4850 post-dyeing. Furthermore, this research underscores improved colorfastness properties, including notable enhancements in light, wash, and rubbing fastness for both silk fabric and wool yarn. These findings underscore the efficacy of the proposed sustainable dyeing methods, offering valuable insights for eco-friendly textile production.

Sugar beet (Beta vulgaris L.) leaves as natural colorant for cotton dyeing using an ecofriendly approach toward industrial progress.

In the industrial sector, vegetable residual materials have received attention in the production of bio-colorant for textile dyeing. The current research endeavor is centered on investigating the possibility of using sugar beet leaves as a natural source of dye for the purpose of dyeing cotton fabrics. Different extraction methods were utilized to isolate the bio-colorant present in sugar beet residual material, and the most favorable colorant yield was obtained using a 5% methanolic KOH solution. For optimal dyeing results, the cotton fabric performed dyeing for a duration of 45 min at a temperature of 60 °C, using a salt solution concentration of 6 g/100 mL and 50 mL of the extracted dye solution. Characterization of dye using Fourier transform infrared spectroscopy analysis confirmed the presence of quercetin in the leaf extract. For the creation of a range of color variations, mordants that were chemical in nature, such as tannic acid, iron sulfate, potassium dichromate, and copper sulfate, as well as mordants that were bio-based, such as onion peel, pomegranate peel, henna, golden shower bark, and turmeric, were employed in harmony. In comparison, the utilization of bio-mordants resulted in darker shades that exhibited enhanced color intensity and superior color fastness properties with the value of 4-5 for wash, 4 for wet rubbing, 4-5 for dry rubbing, and 4-5 for light. The findings of this study hold significant value in terms of ecofriendly waste management and contribute to advancements in the industrial sector by utilizing waste residual materials as a natural source of colorants.

A Comparative Study on Characteristics and Antibacterial Capacity of Cotton Fabrics Dyed with Reactive Dye and Diospyros Mollis Extract.

This article focuses on comparing the characteristics of cotton fabric dyed with Diospyros mollis extract (DME) solution and that of cotton fabric dyed with the reactive dye. The parameters of the cotton fabric after dyeing with both types of dyes were assessed, including color strength (K/S), structural morphology, infrared spectrum, antibacterial properties, UV resistance, color fastness to washing, rubbing, light, moisture absorption, breathability, and wastewater indices. The obtained results show that the K/S value of cotton fabric dyed with DME solution is slightly lower than that of cotton fabric dyed with the reactive dye, 18.52 and 19.36, respectively. The cotton fabric dyed with the reactive dye does not exhibit antibacterial activity against Escherichia coli and Staphylococcus aureus, whereas the antibacterial effectiveness against these bacteria for cotton fabric dyed with DME solution is 99.99 %. The UV protection capability of cotton fabric dyed with DME solution is superior to cotton fabric dyed with the reactive dye. The BOD/COD ratio of wastewater from the dyeing process with DME is higher than that of the reactive dye, with values of 0.70 and 0.32, respectively. The findings of this study indicate the superior ability of using DME solution as compared to the reactive dye, which is promising as a natural dye for fabric in medical applications.

Experimental optical properties explained by density functional theory of the natural red algae for dye-sensitized solar cells application.

The present study investigates the usage of a novel natural dye derived from red algae of Morocco in dye-sensitized solar cells (DSSCs) for the first time. The main pigments responsible for sensitizing the semiconductor TiO2 coatings in the red algae were identified as phycoerythrin, carotenoid, and chlorophyll. The efficiency of a DSSC made from red algae was compared to that of a solar cell made from chlorophyll alone. The photovoltaic performance of the DSSC was evaluated through photocurrent density to photovoltage (J-V) characteristic analysis, and the efficiency was found to be 0.93%. To gain insights into its behavior, the absorbance and photoluminescence in a broad range were studied. Both absorbance and photoluminescence exhibited a broad-spectrum range. Additionally, electronic properties, such as HOMO, LUMO, energy gap, and chemical reactivity parameters, were studied using density functional theory (DFT) calculations.

In Vitro Toxicity Assessment of Cortinarius sanguineus Anthraquinone Aglycone Extract.

Biocolourants could be a sustainable option for dyes that require fossil-based chemicals in their synthesis. We studied the in vitro toxicity of anthraquinone aglycone extract obtained from Cortinarius sanguineus fungus and compared it to the toxicity of its two main components, emodin and previously studied dermocybin. Cell viability, cytotoxicity, and oxidative stress responses in HepG2 liver and THP-1 immune cell lines were studied along with skin sensitisation. In addition, genotoxicity was studied with comet assay in HepG2 cells. Cellular viability was determined by MTT, propidium iodide, and lactate dehydrogenase assays, which showed that the highest doses of both the aglycone extract and emodin affected the viability. However, the effect did not occur in all of the used assays. Notably, after both exposures, a dose-dependent increase in oxidative stress factors was observed in both cell lines as measured by MitoSOX and dihydroethidium assays. C. sanguineus extract was not genotoxic in the comet assay. Importantly, both emodin and the extract activated the skin sensitisation pathway in the KeratinoSens assay, suggesting that they can induce allergy in humans. As emodin has shown cytotoxic and skin-sensitising effects, it is possible that the adverse effects caused by the extract are also mediated by it since it is the main component present in the fungus.

"Purplish Blue" or "Greenish Grey"? Indigo Qualities and Extraction Yields from Six Species.

Indigo quality is determined by its indigotin content. Another quality indicator is colour. For an evaluation of species, indigo samples from Indigofera tinctoria, Indigofera suffruticosa, Indigofera arrecta, Persicaria tinctoria, Strobilanthes cusia and Wrightia laevis cultivated in Austria and China were visually classified and analysed spectrophotometrically and using a L*a*b* measuring device. In addition to a standardised hot-extraction method without lime, some samples were extracted simulating traditional methods at ambient temperatures using lime. The highest indigotin contents were achieved with Indigofera arrecta (55%, Austria) and Strobilanthes cusia (56%, China). There were no statistically significant differences between the indigo extraction yields of the species cultivated in Austria, but Indigofera arrecta and Persicaria tinctoria had statistically significantly higher indigotin extraction yields than Indigofera tinctoria and Indigofera suffruticosa. From the species extracted in China, Strobilanthes cusia showed higher values in all parameters than Indigofera tinctoria, Indigofera suffruticosa and Wrightia laevis. Compared with the standardised method, the method simulating local practice yielded more indigo but had a lower indigotin content; the indigotin extraction yields did not differ greatly. L*a*b* values enabled precise estimations of the indigotin content, making it an interesting option for quality control, as inexpensive, easy-to-handle L*a*b* measuring instruments have become available.