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Kraft pulping of wood is based on efficient depolymerization and solubilization of lignin, while cellulose is relatively undamaged. Non-cellulose cell wall polysaccharides are however in some cases heavily degraded, especially pectin and to a lesser degree also glucomannan while, xylan is relatively stable. In this mini-review, the most important reactions in lignin and polysaccharide degradation in kraft pulping are described, both the technically favorable and the problematic reactions, and the chemical background to discuss the advantages and drawbacks of the process. An attempt to put the different reactions in the perspective of the goals of the pulping process is made and a special focus is on the development of color in the pulp fiber during the kraft pulping. [ABSTRACT FROM AUTHOR]

"Green-covering and red-heart" Guanyin Tuqu (GRTQ), as a type of special fermentation starter, is characterized by the "green-covering" formed on the surface of Guanyin Tuqu (SQ) and the "red-heart" in the center of Guanyin Tuqu (CQ). However, the mechanisms that promote temporal succession in the GRTQ microbial ecology and the formation of "green-covering and red-heart" characteristics remain unclear. Herein, we correlated the temporal profiles of microbial community succession with the main environmental variables (temperature, moisture, and acidity) and spatial position (center and surface) in GRTQ throughout fermentation. According to the results of high-throughput sequencing and culture-dependent methods, the microbial communities in the CQ and SQ demonstrated functional complementarity. For instance, the bacterial richness index of the CQ was greater than that of SQ, and the fungal richness index of the SQ was greater than that of CQ at the later stage of fermentation. Furthermore, Saccharomycopsis, Saccharomyces, Aspergillus, Monascus, Lactobacillus, Bacillus, Rhodanobacter, and Chitinophaga were identified as the dominant microorganisms in the center, while the surface was represented by Saccharomycopsis, Aspergillus, Monascus, Lactobacillus, Acetobacter, and Weissella. By revealing the physiological characteristics of core microorganisms at different spatial positions of GRTQ, such as Aspergillus clavatus and Monascus purpureus, as well as their interactions with environmental factors, we elucidated the color formation mechanism behind the phenomenon of "green" outside and "red" inside. This study provides fundamental information support for optimizing the production process of GRTQ. [ABSTRACT FROM AUTHOR]

Nitrite has been widely used in meat products for its abilities including color formation, antimicrobial properties, flavor formation and preventing lipid oxidation. However, the possible generation of N-nitrosamines through reaction of nitrite with secondary amines arises many concerns in the usage of nitrite. For a long time, nitrite substitution is unsettled issue in the meat industry. Many attempts have been tried, however, the alternative solutions are often ephemeral and palliative. In recent years, bacterial nitric oxide synthase (bNOS) has received attention for its critical roles, especially in reddening meat products. This comprehensive background study summarizes the application of bNOS in colorizing meat products, its functions in bacteria, and methods of regulating the bNOS pathway. Based on this information, some strategies for promoting the nitric oxide yield for effectively substituting nitrite are presented, such as changing the environmental conditions for bacterial survival and adding substrate. Thus, bNOS is a promising nitrite substitute for color formation, and further research on its other roles in meat needs to be carried out to obtain the complete picture. [ABSTRACT FROM AUTHOR]

Morchella sextelata, a highly sought-after edible mushroom worldwide, is evaluated based on its cap color as an essential commercial property indicator. In the present study, the effects of blue light on cap pigmentation in M. sextelata, as well as the synthesis and structural characteristics of melanin pigments within the cap were examined. The results showed that an increase in the proportion of blue light within the lighting environment promoted melanin synthesis and melanization of the cap. Transmission and scanning electron microscopy revealed the localization of melanin within the mycelium and its ultrastructural characteristics. The UV-visible analysis demonstrated that melanin exhibited a maximum absorption peak at 220 nm and possessed high alkaline solubility as well as acid precipitability. The structural characteristics of melanin were analyzed using FTIR, NMR, HPLC, and elemental analysis, which confirmed the presence of eumelanin, pheomelanin, and allomelanin in both brown and black caps. Furthermore, blue light can stimulate the synthesis of both eumelanin and pheomelanin. The obtained results can serve as the foundation for comprehending the mechanism by which light regulates color formation in mushrooms. [ABSTRACT FROM AUTHOR]

This study investigated the microbial community in three-color sauce-flavor Daqu (black, yellow, and white) throughout their maturation processes, together with their physicochemical factors, culturable microbes, flavor components, and fermenting vitalities. Results from high-throughput sequencing revealed distinct microbial diversity, with more pronounced variations in bacterial community than in fungal community. Firmicutes and Ascomycota emerged as the most dominant bacterial and fungal phyla, respectively, during maturation. Genus-level analysis identified Kroppenstedia, Virgibacillus, and Bacillus as dominant bacteria in black Daqu, yellow Daqu, and white Daqu, severally, while Thermoascus was shared as the core dominant fungi for these Daqu. Physicochemical factors, particularly acidity, were found to exert a significant impact on microbial community. Kroppenstedtia was the key bacteria influencing the color formation of these Daqu. Furthermore, correlations between dominant microbes and flavor compounds highlighted their role in Daqu quality. Molds (Aspergillus, Rhizomucor, and Rhizopus), excepting Bacillus, played a crucial role in the formation of pyrazine compounds. Consequently, this study offers innovative insights into the microbial perspectives on color and pyrazine formation, establishing a groundwork for future mechanized Daqu production and quality control of sauce-flavor baijiu. [ABSTRACT FROM AUTHOR]

Carotenoids are important pigments in pepper fruits. The colors of each pepper are mainly determined by the composition and content of carotenoid. The 'ZY' variety, which has yellow fruit, is a natural mutant derived from a branch mutant of 'ZR' with different colors. ZY and ZR exhibit obvious differences in fruit color, but no other obvious differences in other traits. To investigate the main reasons for the formation of different colored pepper fruits, transcriptome and metabolome analyses were performed in three developmental stages (S1–S3) in two cultivars. The results revealed that these structural genes (PSY1, CRTISO, CCD1, CYP97C1, VDE1, CCS, NCED1 and NCED2) related to carotenoid biosynthesis were expressed differentially in the two cultivars. Capsanthin and capsorubin mainly accumulated in ZR and were almost non-existent in ZY. S2 is the fruit color-changing stage; this may be a critical period for the development of different color formation of ZY and ZR. A combination of transcriptome and metabolome analyses indicated that CCS, NCED2, AAO4, VDE1 and CYP97C1 genes were key to the differences in the total carotenoid content. These new insights into pepper fruit coloration may help to improve fruit breeding strategies. [ABSTRACT FROM AUTHOR]

Morchella sextelata, a highly sought-after edible mushroom worldwide, is evaluated based on its cap color as an essential commercial property indicator. In the present study, the effects of blue light on cap pigmentation in M. sextelata, as well as the synthesis and structural characteristics of melanin pigments within the cap were examined. The results showed that an increase in the proportion of blue light within the lighting environment promoted melanin synthesis and melanization of the cap. Transmission and scanning electron microscopy revealed the localization of melanin within the mycelium and its ultrastructural characteristics. The UV–visible analysis demonstrated that melanin exhibited a maximum absorption peak at 220 nm and possessed high alkaline solubility as well as acid precipitability. The structural characteristics of melanin were analyzed using FTIR, NMR, HPLC, and elemental analysis, which confirmed the presence of eumelanin, pheomelanin, and allomelanin in both brown and black caps. Furthermore, blue light can stimulate the synthesis of both eumelanin and pheomelanin. The obtained results can serve as the foundation for comprehending the mechanism by which light regulates color formation in mushrooms.

IntorductionColoration is a prominent trait in fish that is closely linked to their market value. Fish exhibit a diverse range of body colors, making them an excellent model for studying molecular mechanisms underlying pigmentation. Although regulatory pathways involved in pigmentation have been extensively studied in model fish such as zebrafish and medaka, the presence of varying chromatophore types across different fish species suggests that fish pigmentation mechanisms are not fixed. Therefore, more studies should be conducted on non-model fish. Sinibrama taeniatus is an endemic fish in the upper Yangtze River that is highly valued for its ornamental and edible properties.MethodsIn this study, we identified three chromatophore types in S. taeniatus and investigated changes in body color, chromatophores, and pigments at different developmental stages. Subsequently, RNA-seq analysis revealed that retinol metabolism, thyroid hormone synthesis, purine metabolism, and pyrimidine metabolism pathway are closely associated with pigmentation.ResultsWeighted gene co-expression network analysis (WGCNA) identified several hub genes, including mitf, wnt 9a, wnt10b, wnt11, adcy5, edn1, adcy8, and rdh8, that may play an important role in pigmentation.DiscussionOverall, our findings provide valuable insights into the role of genes and pathways in fish pigmentation and offer useful information for body color-based molecular breeding programs in aquaculture.

In this paper, the effect of different concentrations of sucrose stress on color formation of the Staphylococcus xylosus was investigated. The results showed that the highest a * value and the best coloring effect similar to those of nitrite were observed after the addition of 0.05 g/mL sucrose to stress the S. xylosus. UV-Vis and electron spin resonance spectra analysis showed that production of coloring product Mb-NO was significantly enhanced after 0.05 g/mL sucrose stress. The growth curve, reactive oxygen content, cell cycle, nitric oxide synthase (NOS) activity, zeta potential, cell size, and protein composition of S. xylosus were investigated to reveal the mechanism of sucrose stress to enhance the coloring effect of the strain. The result showed that sucrose inhibited the growth of S. xylosus , which changed the physiological state by activating the oxidative stress response. The stress altered the rate of intracellular metabolism of S. xylosus by delaying the cell cycle and increasing cell surface zeta potential and cell particle size. These changes altered the protein composition of the cells and significantly enhanced the activity of intracellular NOS, which could improve the chromogenic ability of S. xylosus. This study will provide theoretical support for sucrose stress on S. xylosus to enhance its coloring effect, and sucrose stress for S. xylosus might be a promising biological alternative to nitrite in meat products. [ABSTRACT FROM AUTHOR]

Carotenoids are important pigments in pepper fruits. The colors of each pepper are mainly determined by the composition and content of carotenoid. The ‘ZY’ variety, which has yellow fruit, is a natural mutant derived from a branch mutant of ‘ZR’ with different colors. ZY and ZR exhibit obvious differences in fruit color, but no other obvious differences in other traits. To investigate the main reasons for the formation of different colored pepper fruits, transcriptome and metabolome analyses were performed in three developmental stages (S1–S3) in two cultivars. The results revealed that these structural genes (PSY1, CRTISO, CCD1, CYP97C1, VDE1, CCS, NCED1 and NCED2) related to carotenoid biosynthesis were expressed differentially in the two cultivars. Capsanthin and capsorubin mainly accumulated in ZR and were almost non-existent in ZY. S2 is the fruit color-changing stage; this may be a critical period for the development of different color formation of ZY and ZR. A combination of transcriptome and metabolome analyses indicated that CCS, NCED2, AAO4, VDE1 and CYP97C1 genes were key to the differences in the total carotenoid content. These new insights into pepper fruit coloration may help to improve fruit breeding strategies.

To explore the mechanisms of the color formation of different colored persimmon fruits, we used two different colored persimmon cultivars (yellow-peeled persimmon fruit 'Zhongshi No.6' and red-peeled persimmon fruit 'Hongdenglong') as materials to study the synthesis and accumulation of carotenoids in three stages (full green, color transition, and full yellow or red) using targeted metabolomic and transcriptomic methods. A total of 14 carotenoids and 30 carotenoid lipids were identified in the peel of the two persimmon cultivars. After analysis, it was found that the total carotenoid content of the red persimmon cultivar was higher than that of the yellow persimmon cultivar. The contents of lycopene, α-carotenoid, β-carotenoid, (E/Z)-phytoene, and β-cryptoxanthin are the main reasons for the difference in total carotenoid content between the two persimmon cultivars, especially lycopene. Twelve structural genes involved in the metabolism of carotenoids were also found in this study. In comprehensive metabolome and transcriptome analysis, we found that, between the two persimmon cultivars, lycopene was the key metabolite responsible for the color difference, and PSY, LCYE, and ZDS were the key genes that regulated the differences in lycopene accumulation. The results of this study provide us with new information regarding persimmon fruit synthesis and accumulation. In addition, they also provide a theoretical foundation for improving persimmon fruit germplasm. [ABSTRACT FROM AUTHOR]

Abstract Background The bast fiber crop ramie can be used as high-quality forage resources, especially in tropical or subtropical region where there is lack of high-quality protein feed. Hongxuan No.1 (HX_1) is a unique ramie variety with a light reddish brown leaf color, which is obviously different from elite cultivar, Zhongzhu No.1 (ZZ_1, green leaf). While, the regulatory mechanism of color difference or secondary metaboliates synthesis between these two varieties have not been studied. Results In this study, phenotypic, transcriptomic and metabolomic analysis of HX_1 and ZZ_1 were conducted to elucidate the mechanism of leaf color formation. Chromaticity value and pigment content measuring showed that anthocyanin was the main metabolites imparting the different leaf color phenotype between the two varieties. Based on LC/MS, at least 14 anthocyanins were identified in leaves of HX_1 and ZZ_1, and the HX_1 showed the higher relative content of malvidin-, pelargonidin-,and cyanidin-based anthocyanins. Transcriptome and metabolome co-analysis revealed that the up-regulated expression of flavonoids synthesis gene was positively correlated with total anthocyanins accumulation in ramie leaf, and the differentfially expression of “blue gene” (F3’5’H) and the “red gene” (F3’H) in leaves bring out HX_1 metabolic flow more input into the cyanidin branch. Furthermore, the enrichment of glycosylated modification pathway (UGT and AT) and the expression of flavonoid 3-O-glucosyl transferase (UFGT), anthocyanidin reductase (ANR), in leaves were significantly influenced the diversity of anthocyanins between HX_1 and ZZ_1. Conclusions Phenotypic, transcriptomic and metabolomic analysis of HX_1 and ZZ_1 indicated that the expression levels of genes related to anthocyanin metabolism contribute to the color formation of ramie variety. Anthocyanins are important plant secandary metabilates with many physiological functions, the results of this study will deepened our understanding of ramie leaf color formation, and provided basis for molecular breeding of functional forage ramie.

Yellow roots are of higher nutritional quality and better appearance than white roots in cassava, a crucial tropical and subtropical root crop. In this work, two varieties with yellow and white cassava roots were selected to explore the mechanisms of color formation by using comparative metabolome and transcriptome analyses during seven developmental stages. Compared with the white-rooted cassava, anthocyanins, catechin derivatives, coumarin derivatives, and phenolic acids accumulated at higher levels in yellow-rooted cassava. Anthocyanins were particularly enriched and displayed different accumulation patterns during tuberous root development. This was confirmed by metabolic comparisons between five yellow-rooted and five white-rooted cassava accessions. The integrative metabolomic and transcriptomic analysis further revealed a coordinate regulation of 16 metabolites and 11 co-expression genes participating in anthocyanin biosynthesis, suggesting a vital role of anthocyanin biosynthesis in yellow pigmentation in cassava tuberous roots. In addition, two transcriptional factors, i.e., MeMYB5 and MeMYB42, were also identified to co-express with these anthocyanin biosynthesis genes. These findings expand our knowledge on the role of anthocyanin biosynthesis in cassava root color formation, and offer useful information for the genetic breeding of yellow-rooted cassava in the future.

"Green-covering and red-heart" Guanyin Tuqu (GRTQ), as a type of special fermentation starter, is characterized by the "green-covering" formed on the surface of Guanyin Tuqu (SQ) and the "red-heart" in the center of Guanyin Tuqu (CQ). However, the mechanisms that promote temporal succession in the GRTQ microbial ecology and the formation of "green-covering and red-heart" characteristics remain unclear. Herein, we correlated the temporal profiles of microbial community succession with the main environmental variables (temperature, moisture, and acidity) and spatial position (center and surface) in GRTQ throughout fermentation. According to the results of high-throughput sequencing and culture-dependent methods, the microbial communities in the CQ and SQ demonstrated functional complementarity. For instance, the bacterial richness index of the CQ was greater than that of SQ, and the fungal richness index of the SQ was greater than that of CQ at the later stage of fermentation. Furthermore, Saccharomycopsis , Saccharomyces , Aspergillus , Monascus , Lactobacillus , Bacillus , Rhodanobacter , and Chitinophaga were identified as the dominant microorganisms in the center, while the surface was represented by Saccharomycopsis , Aspergillus , Monascus , Lactobacillus , Acetobacter , and Weissella . By revealing the physiological characteristics of core microorganisms at different spatial positions of GRTQ, such as Aspergillus clavatus and Monascus purpureus , as well as their interactions with environmental factors, we elucidated the color formation mechanism behind the phenomenon of "green" outside and "red" inside. This study provides fundamental information support for optimizing the production process of GRTQ., Competing Interests: LiZ, LC, BL, YX, YL, JT, GZ, LeZ, SY, QY, and SC were employed by the Jing Brand Co., Ltd. The remaining author declares that the research was conducted in the absence of any commercial or financial relationships that could be construed as a potential conflict of interest., (Copyright © 2024 Zhu, Chen, Lin, Xu, Dong, Lv, Tang, Zhang, Zhang, Yang, Yang and Chen.)

The aim of the work is to determine the color formation of multicomponent fruit and vegetable pastes and dried powder fractions at the stages of low-temperature pre-concentration and drying, as one of the factors, maintaining the quality of the products. In the production of organic plant semi-finished products an important factor is the implementation of high-quality technological operations, including heat and mass transfer, which affects the final organoleptic characteristics of products. It is important to take into account the color of raw materials at the stages of blending puree in the production of paste and powder semi-finished products, which requires the introduction of a unified method for assessing the color of raw materials at each stage of the technological operation. An analysis of traditional methods for determining color formation has been performed, as a result of which it has been found, that the most effective method of evaluation is digital, based on photo processing of the prototype. According to this method, the evaluation of color formation in the manufacture of semi-finished fruits and vegetables in accordance with the proposed recipes has been conducted. Color indices of multicomponent pastes and dried fractions based on them for three prototypes were obtained. The brightness of all samples of pastes is in the range - 36.4... 37.0 % with a purity of tone 64.7... 78.2 %, which corresponds to the reddish-orange color, was obtained. After drying the test samples of pastes to the dried fraction, it has been found, that the brightness, depending on the percentage of raw materials in a sample falls in the range of 30.5... 33.2 %, at that the coloration corresponds to colors from bluish-purple to bluish-red with a purity of tone within 34.7... 34.9 %. As a result of evaluation of organoleptic indicators, it has been found, that according to the presented research samples, the best indicators have a sample with 40 % of raw apples, 20 % of pumpkin, 30 % of cranberries and 10 % of hawthorn. The obtained research data will be useful in the development of methods for the production of semi-finished products from vegetable raw materials. The applied digital method of color determination differs in simplicity and economy in comparison with colorimetric and spectrometric. [ABSTRACT FROM AUTHOR]

Colored wheat grains have a unique nutritional value. To elucidate the color formation mechanism in wheat seeds, comprehensive metabolomic and transcriptomic analyses were conducted on purple (Dianmai 20-1), blue (Dianmai 20-8), and white (Dianmai 16) wheat at the grain-filling stage. The results showed that the flavonoid biosynthesis pathway was closely related to grain color formation. Among the 603 metabolites identified in all varieties, there were 98 flavonoids. Forty-six flavonoids were detected in purple and blue wheat, and there were fewer flavonoids in white wheat than in colored wheat. Integrated transcriptomic and metabolomic analyses showed that gene expression modulated the flavonoid composition and content, resulting in different metabolite levels of pelargonidin, cyanidin, and delphinidin, thus affecting the color formation of wheat grains. The present study clarifies the mechanism by which pigmentation develops in wheat grains and provides an empirical reference for colored wheat breeding. [ABSTRACT FROM AUTHOR]

Background: The bast fiber crop ramie can be used as high-quality forage resources, especially in tropical or subtropical region where there is lack of high-quality protein feed. Hongxuan No.1 (HX_1) is a unique ramie variety with a light reddish brown leaf color, which is obviously different from elite cultivar, Zhongzhu No.1 (ZZ_1, green leaf). While, the regulatory mechanism of color difference or secondary metaboliates synthesis between these two varieties have not been studied. Results: In this study, phenotypic, transcriptomic and metabolomic analysis of HX_1 and ZZ_1 were conducted to elucidate the mechanism of leaf color formation. Chromaticity value and pigment content measuring showed that anthocyanin was the main metabolites imparting the different leaf color phenotype between the two varieties. Based on LC/MS, at least 14 anthocyanins were identified in leaves of HX_1 and ZZ_1, and the HX_1 showed the higher relative content of malvidin-, pelargonidin-,and cyanidin-based anthocyanins. Transcriptome and metabolome co-analysis revealed that the up-regulated expression of flavonoids synthesis gene was positively correlated with total anthocyanins accumulation in ramie leaf, and the differentfially expression of "blue gene" (F3'5'H) and the "red gene" (F3'H) in leaves bring out HX_1 metabolic flow more input into the cyanidin branch. Furthermore, the enrichment of glycosylated modification pathway (UGT and AT) and the expression of flavonoid 3-O-glucosyl transferase (UFGT), anthocyanidin reductase (ANR), in leaves were significantly influenced the diversity of anthocyanins between HX_1 and ZZ_1. Conclusions: Phenotypic, transcriptomic and metabolomic analysis of HX_1 and ZZ_1 indicated that the expression levels of genes related to anthocyanin metabolism contribute to the color formation of ramie variety. Anthocyanins are important plant secandary metabilates with many physiological functions, the results of this study will deepened our understanding of ramie leaf color formation, and provided basis for molecular breeding of functional forage ramie. [ABSTRACT FROM AUTHOR]

To explore the mechanisms of the color formation of different colored persimmon fruits, we used two different colored persimmon cultivars (yellow-peeled persimmon fruit ‘Zhongshi No.6’ and red-peeled persimmon fruit ‘Hongdenglong’) as materials to study the synthesis and accumulation of carotenoids in three stages (full green, color transition, and full yellow or red) using targeted metabolomic and transcriptomic methods. A total of 14 carotenoids and 30 carotenoid lipids were identified in the peel of the two persimmon cultivars. After analysis, it was found that the total carotenoid content of the red persimmon cultivar was higher than that of the yellow persimmon cultivar. The contents of lycopene, α-carotenoid, β-carotenoid, (E/Z)-phytoene, and β-cryptoxanthin are the main reasons for the difference in total carotenoid content between the two persimmon cultivars, especially lycopene. Twelve structural genes involved in the metabolism of carotenoids were also found in this study. In comprehensive metabolome and transcriptome analysis, we found that, between the two persimmon cultivars, lycopene was the key metabolite responsible for the color difference, and PSY, LCYE, and ZDS were the key genes that regulated the differences in lycopene accumulation. The results of this study provide us with new information regarding persimmon fruit synthesis and accumulation. In addition, they also provide a theoretical foundation for improving persimmon fruit germplasm.

• Ten metabolic biomarkers were identified to distinguish specific Chinese cherry accessions. • The various color of Chinese cherry fruits was collectively determined by twenty-six structurally unique anthocyanins. • Cyanidins played a dominant role in the color formation of Chinese cherry fruits. • Limocitrin-7-O-glucoside and eight other compounds were potentially contributing to Chinese cherry fruits' bitter flavor. Chinese cherry [ Cerasus pseudocerasus (Lindl.) G.Don], native to China, is an economically important fruit crop with attractive colors and delicious flavors. However, the specific metabolites present in cherry fruits have remained unknown. Here, we firstly characterized 1439 metabolite components of Chinese cherry fruits, predominantly including amino acids, flavonoids, and phenolic acids. Moreover, we screened ten biomarkers of Chinese cherry accessions by ROC curve analysis. Among 250 flavonoids, 26 structurally unique anthocyanins collectively determined fruit color, with cyanidins playing a dominant role. Differences in accumulated metabolites between anthocyanin and proanthocyanidin pathways were likely responsible for the variation in fruit color, ranging from yellow to black purple. Meanwhile, we found limocitrin-7-O-glucoside, along with eight other compounds, as underlying contributors to bitter off-taste experienced in fruits. This study provides insights into the regulatory network of metabolites involved in color variation and bitterness formation and genetic improvement of Chinese cherry fruits. [ABSTRACT FROM AUTHOR]

This study investigated the microbial community in three-color sauce-flavor Daqu (black, yellow, and white) throughout their maturation processes, together with their physicochemical factors, culturable microbes, flavor components, and fermenting vitalities. Results from high-throughput sequencing revealed distinct microbial diversity, with more pronounced variations in bacterial community than in fungal community. Firmicutes and Ascomycota emerged as the most dominant bacterial and fungal phyla, respectively, during maturation. Genus-level analysis identified Kroppenstedia , Virgibacillus , and Bacillus as dominant bacteria in black Daqu , yellow Daqu , and white Daqu , severally, while Thermoascus was shared as the core dominant fungi for these Daqu . Physicochemical factors, particularly acidity, were found to exert a significant impact on microbial community. Kroppenstedtia was the key bacteria influencing the color formation of these Daqu . Furthermore, correlations between dominant microbes and flavor compounds highlighted their role in Daqu quality. Molds ( Aspergillus , Rhizomucor , and Rhizopus ), excepting Bacillus , played a crucial role in the formation of pyrazine compounds. Consequently, this study offers innovative insights into the microbial perspectives on color and pyrazine formation, establishing a groundwork for future mechanized Daqu production and quality control of sauce-flavor baijiu., Competing Interests: WD, QY, and SC were employed by Jing Brand Co., Ltd. The remaining authors declare that the research was conducted in the absence of any commercial or financial relationships that could be construed as a potential conflict of interest., (Copyright © 2024 Dong, Yu, Wang, Zou, Ma, Liu, Feng, Zhao, Yang, Hu and Chen.)

• CircRNAs are detected in developing flowers of melastoma candidum. • CircRNAs may originate from the alternative splicing process of genes. • CircRNAs sponge miRNAs to regulate genes related to flower development. • CircRNAs regulate compounds synthesis via ceRNA regulatory mechanism. Melastoma candidum D. Don is widely distributed in South China. However, its application in the garden industry is not ideal due to its sole flower color; thus, its color needs urgent improvement. In this study, we conducted high throughput transcriptome sequencing for circular RNA (circRNA), mRNA, small RNA (sRNA), and widely targeted metabolome in flowers at three developmental stages. RNA expression and metabolite abundance analyses identified differentially expressed circRNAs (DEcircRNAs), mRNAs (DEmRNAs), miRNAs (DEmiRNAs), and differentially synthesized metabolites (DSmets). Alternative variants of genes were given statistics and the reason for their occurrence was analyzed. GO enrichment and KEGG analyses were conducted on the source gene of DEcircRNAs and KEGG analyses on DSmets. Key genes and metabolites were identified in flavonoid, flavone, anthocyanin, carotenoid, and alkaloid biosynthetic pathways. Based on the above analyses, we built a circRNA-mediated ceRNA regulatory network. Nine circRNA-mediated ceRNA regulatory routines were obtained. Within the ceRNA regulatory network, circRNAs and mRNAs displayed positive correlations, both of which exhibit negative correlations with miRNAs, indicating their important roles during flower development and color formation of M. candidum. Amongst, circ_000434-miR5207- McF3H could regulate the biosynthesis of Dihydroquercetin, Dihydromyricetin, and Pinobanksin; circ_000302-miR319–5p- McHST and circ_00012 -miR826- McTAT could regulate the biosynthesis of p -Counmaryl shikimic acid. Our research explored the role of circRNAs in flower development and the color formation process and provided a theoretical foundation for flower color improvement in M. candidum. [ABSTRACT FROM AUTHOR]

Purple pakchoi (Brassica rapa ssp. Chinensis) is particularly appreciated due to its high edible quality and ornamental value, but there are few studies on the underlying mechanisms of leaf color formation. To comprehensively assess the differences in purple formation in pakchoi, four lines of pakchoi with different purple leaves were used in this experiment to determine the pigment content and to investigate the distribution and components of anthocyanin using LCMS (Liquid Chromatography Mass Spectrometry) and leaf cross-sections. Moreover, the expression levels of anthocyanin synthesis-related genes in four lines were calculated by qRT-PCR. The results showed that three new purple lines rich in anthocyanin and of high-quality were bred, and the anthocyanin were mainly distributed in both the upper epidermis and lower epidermis of leaves. Thirteen anthocyanin components were separated and identified, all the anthocyanins were acylated and glycosylated cyanidins; the main anthocyanins in purple pakchoi were a diacylated form of cyanidin 3-trans-(feruloyl)diglucoside-5-(malonyl)glucoside. Both the ratio of non-aromatic acylated cyanidin to aromatic acylated cyanidin and the ratio of anthocyanin content to chlorophyll content were responsible for the color formation in different purple pakchoi lines. When the ratio was high, the leaf appeared reddish purple, and when the ratio was low, the leaf appeared deep purple, even blackish purple. The expression level of BrF3H was significantly correlated with the content of anthocyanin through the correlation coefficient, which was speculated to be the main anthocyanin synthesis-related gene resulting in color differences among the four purple pakchoi lines. These results will enhance our understanding for the cultivation of new purple pakchoi varieties.

Morchella sextelata , a highly sought-after edible mushroom worldwide, is evaluated based on its cap color as an essential commercial property indicator. In the present study, the effects of blue light on cap pigmentation in M. sextelata , as well as the synthesis and structural characteristics of melanin pigments within the cap were examined. The results showed that an increase in the proportion of blue light within the lighting environment promoted melanin synthesis and melanization of the cap. Transmission and scanning electron microscopy revealed the localization of melanin within the mycelium and its ultrastructural characteristics. The UV-visible analysis demonstrated that melanin exhibited a maximum absorption peak at 220 nm and possessed high alkaline solubility as well as acid precipitability. The structural characteristics of melanin were analyzed using FTIR, NMR, HPLC, and elemental analysis, which confirmed the presence of eumelanin, pheomelanin, and allomelanin in both brown and black caps. Furthermore, blue light can stimulate the synthesis of both eumelanin and pheomelanin. The obtained results can serve as the foundation for comprehending the mechanism by which light regulates color formation in mushrooms., Competing Interests: The authors declare that the research was conducted in the absence of any commercial or financial relationships that could be construed as a potential conflict of interest., (Copyright © 2023 Qiu, Wang, Zhao, Cui, Wang, Cai, Li, Ren, Li and Shu.)

Anthocyanins can be induced by environmental factors such as low-temperature and play essential roles in plant color formation. In this study, leaves of Aesculus chinensis Bunge var. chinensis with different colors under natural low-temperature in autumn were collected and grouped into green leaf (GL) and red leaf (RL). To reveal the underlying mechanism of color formation in RL, a combined analysis of the metabolome and transcriptome was conducted with GL and RL. Metabolic analyses revealed that total anthocyanin content and primary anthocyanin components were increased RL relative to GL and cyanidin was the main anthocyanin compound in RL. Transcriptome analysis provided a total of 18720 differentially expressed genes (DEGs), of which 9150 DEGs were upregulated and 9570 DEGs were downregulated in RL relative to GL. KEGG analysis showed that DEGs were mainly enriched in flavonoid biosynthesis, phenylalanine metabolism, and phenylpropanoid biosynthesis. Furthermore, co-expression network analysis indicated that 56 AcMYB transcription factors were highly expressed in RL compared with GL, among which AcMYB113 (an R2R3-MYB TF) had a strong correlation with anthocyanins. Overexpression of AcMYB113 in apple resulted in dark-purple transgenic calluses. In addition, the transient expression experiment showed that AcMYB113 enhanced anthocyanin synthesis by activating pathways of anthocyanin biosynthesis in leaves of Aesculus chinensis Bunge var. chinensis. Taken together, our findings reveal new insights into the molecular mechanism of anthocyanin accumulation in RL and provide candidate genes for the breeding of anthocyanin-rich cultivars. • Total anthocyanin content and primary anthocyanin components were increased RL relative to GL. • The DEGs were mainly enriched in flavonoid biosynthesis, phenylalanine metabolism, and phenylpropanoid biosynthesis. • Overexpression of AcMYB113 enhanced anthocyanin synthesis by activating the pathways of anthocyanin biosynthesis. [ABSTRACT FROM AUTHOR]

6-pyruvoyl-tetrahydropterin synthase (PTPS) is the second key enzyme of the pteridine biosynthetic pathway and it plays vital roles in fish body color formation. In this study, Ccptps of koi carp (Cyprinus carpio L.) was cloned, identified and characterized. The full-length cDNA of Ccptps was 1140 bp and encodes for 139 amino acids. Multiple alignments revealed that the amino acids sequence of CcPTPS shared the highest identity to that of C. carpio , and Ccptps was clustered with cyprinid fishes in phylogenetic tree. Liver tissues of koi carp exhibited the highest expression of Ccptps , followed by muscle and skin tissues. During early developmental stages, the expression of Ccptps declined from 2 dph to 4 dph, and increased from 4 dph to 12 dph. The expressions of Ccptps in three color-related tissues (skin, scale and caudal fin) of whole red (WR) koi carp were significantly higher than that of whole while (WW) koi carp. Immunohistochemistry results of skin tissues showed that CcPTPS was mainly located in epidermis, stratum compactum of dermis and muscle layer, with the signal intensities in stratum compactum and muscle layer were stronger in WR koi carp compared to WW koi carp. Co-expressions of CcPTPS, CcSPR and CcXDH were detected in skin tissues of WW and WR koi carps, with CcPTPS exhibited stronger signal intensity compared to CcSPR and CcXDH. These findings imply that Ccptps is potentially involved in koi carp body color formation through the pteridine synthesis pathway. [Display omitted] • A pteridine synthesis related gene Ccptps was cloned and characterized in koi carp. • The expressions of Ccptps were closely related to tissue colors. • The co-expression of CcPTPS, CcSPR and CcXDH was detected in skin of koi carp. • Ccptps may be involved in body color formation through pteridine synthesis pathway. [ABSTRACT FROM AUTHOR]

The effect of pre-formed lipid hydroperoxides, breading, and battering ingredients on pigment formation and thermo-oxidative degradation of oil during institutional frying was evaluated. The food ingredients were fried intermittently in canola oil heated for 8 h daily over 4 consecutive days at 185 ± 5°C. Color component formation, total polar components (TPC), and tocopherols were measured. Glycine-enriched whey protein fried in 1% oxidized canola oil contributed most significantly to oil darkening with a rate ten times that of the control sample. Using whey protein as a base for battering caused the most significant color changes and thermo-oxidative deterioration. Glucose and glycine are two minor ingredients that also contribute to color formation in oil. Breading materials were prone to cause a more significant amount of oil deterioration when compared to battering ingredients most likely due to excess loose breading particles falling into the oil during frying. Practical applications: The present study evaluated the effect of some components of food coatings on the stability and pigment formation of the frying oil. The results suggest the need to optimize the protein component of coating materials and ensure that the amounts of loose particles on breaded products are adequately minimized. This information will assist institutional frying operators and other relevant industries in product development and food preparation with the view of optimizing performance of the frying oil. [ABSTRACT FROM AUTHOR]

Abstract: Enzymatic modification of proteins, in order to produce functional materials such as hydrogels, adhesives and films via cross-linked networks or scaffolds of proteins, is a constantly evolving technology to create tailored micro- and nanostructured materials for food, cosmetic, and medical applications. For the successful utilization of oxidoreductases or transferases such as tyrosinases and transglutaminases, respectively, it is crucial to understand the action of these enzymes on protein substrates. In this study, cross-linking of the milk protein β-casein by Trichoderma reesei tyrosinase (TrTyr) was studied using size-exclusion chromatography (SEC) equipped with multi-angle light scattering (MALLS) and ultraviolet/visible (UV/Vis) detectors in order to determine the molecular mass (MM), radius of gyration (R G) and degree of polymerization (DP) of the reaction products. Sodium dodecyl sulphate-polyacrylamide gel electrophoresis (SDS-PAGE) was used to detect early polymerization states. The widely used Streptoverticillium mobaraense transglutaminase (Tgase) was used for comparison to tyrosinase from T. reesei. The results showed that cross-linking of β-casein by these two different types of enzymes resulted in the formation of polymerized reaction products with MM ranging from 500 to 1700 kg mol−1 depending on the enzyme dosage and incubation time. The DP varied from 21 to 71, respectively. In the case of TrTyr the polymerized reaction products were slightly colored, and formation of the covalent cross-linking of β-casein could be monitored by UV/Vis as a function of incubation time. [Copyright &y& Elsevier]

The swallowtail butterfly Papilio xuthus changes its larval body pattern dramatically during the fourth ecdysis. The penultimate (fourth) instar larvae mimic bird droppings that have many tubercle structures on their surface, whereas the final (fifth) instar larvae have a green camouflage color. To identify the genes involved in stage-specific larval mimicry markings, we compared the epidermal messenger ribonucleic acid expression between the third and fourth molts of P. xuthus using a complementary deoxyribonucleic acid subtraction method. After analyzing 2,072 clones from two subtractive libraries, we obtained 31 and 64 candidate genes for final (Fsg) or penultimate instar-specific genes (Psg), respectively. The expression pattern of each gene was examined by reverse transcriptase polymerase chain reaction and in situ hybridization. Among Fsgs, Fsg02 and Fsg20 were expressed in the presumptive green region only during the fourth molt, suggesting that these two genes were correlated with green coloration in the final instar. Among Psgs, 11 cuticular protein genes were expressed specifically in the tubercle structures during the third molt. These genes are likely to be involved in the formation of the unique tubercle structures observed in the juvenile instar. We found that genes with similar expression patterns do not necessarily share the same protein motifs and vice versa. This study provides novel molecular markers and insights into the molecular mechanisms of the larval color pattern and body shape. [ABSTRACT FROM AUTHOR]

Like the adult wing, butterfly larvae are unique in their coloring. However, the molecular mechanisms underlying the formation of insect larval color patterns are largely unknown. The larva of the swallowtail butterfly Papilio xuthus changes its color pattern markedly during the 4th ecdysis. We investigated its cuticular color pattern, which is thought to be composed of melanin and related pigments derived from tyrosine. We cloned three enzymes involved in the melanin-synthesis pathway in P. xuthus: tyrosine hydroxylase ( TH), dopa decarboxylase ( DDC), and ebony. Whole-mount in situ hybridization showed that the expression of both TH and DDC is strongly correlated with the black markings. ebony is strongly expressed only in the reddish-brown area. The expression pattern of each enzyme coincides with the cuticular color pattern of the subsequent instar. We also investigated the uptake of melanin precursors into cultured integument. Inhibition of either TH or DDC activity prevents in vitro pigmentation completely. Addition of dopamine to integuments in the presence of TH inhibitor causes overall darkening without specific markings. From these results, specific larval cuticular color patterns are regulated by stage-specific colocalization of enzymes in epidermal cells rather than by the differential uptake of melanin precursors into individual epidermal cells. Epidermal cells expressing TH and DDC, but not ebony, produce the black cuticle, and epidermal cells expressing TH, DDC, and ebony produce the reddish-brown cuticle. [ABSTRACT FROM AUTHOR]

The emission of sulfur dioxide (SO2) from linear alkylbenzene sulfonate (LAS) acid (LASH) at high temperatures has been studied. Rate constants and Arrhenius parameters have been determined, enabling estimation of the amount of SO2 evolved under any time/temperature combination for risk assessment purposes. Further analysis of the kinetic data and comparison with earlier molecular modeling work on the mechanism of sulfonation of linear alkyl benzene (LAB) to make LASH provide insight into the reaction pathway of SO2 formation by thermal decomposition of LASH. For risk assessment purposes, the calculation is as follows: Estimate k from k=3.9×107·e−13,000/(273+ T), where T is in degrees C and k is in s−1. Estimate N(SO2, t), the number of moles of SO2 evolved when N(LASH0) moles of LASH are heated for t s at T oC, from: N(SO2, t)= N(LASH0)×(1−e− kt ). [ABSTRACT FROM AUTHOR]

Yellow roots are of higher nutritional quality and better appearance than white roots in cassava, a crucial tropical and subtropical root crop. In this work, two varieties with yellow and white cassava roots were selected to explore the mechanisms of color formation by using comparative metabolome and transcriptome analyses during seven developmental stages. Compared with the white-rooted cassava, anthocyanins, catechin derivatives, coumarin derivatives, and phenolic acids accumulated at higher levels in yellow-rooted cassava. Anthocyanins were particularly enriched and displayed different accumulation patterns during tuberous root development. This was confirmed by metabolic comparisons between five yellow-rooted and five white-rooted cassava accessions. The integrative metabolomic and transcriptomic analysis further revealed a coordinate regulation of 16 metabolites and 11 co-expression genes participating in anthocyanin biosynthesis, suggesting a vital role of anthocyanin biosynthesis in yellow pigmentation in cassava tuberous roots. In addition, two transcriptional factors, i.e., MeMYB5 and MeMYB42 , were also identified to co-express with these anthocyanin biosynthesis genes. These findings expand our knowledge on the role of anthocyanin biosynthesis in cassava root color formation, and offer useful information for the genetic breeding of yellow-rooted cassava in the future., Competing Interests: The authors declare that the research was conducted in the absence of any commercial or financial relationships that could be construed as a potential conflict of interest., (Copyright © 2022 Fu, Ding, Tie, Yang, Yan and Hu.)

The mechanism of possible incompatibility between commercially available metronidazole parenteral solutions and the injectable aztreonam leading to the development of pink color in their intravenous admixtures was studied. It was demonstrated that nitrite ions may be produced in metronidazole solutions at the time of preparation or during storage by the effects of temperature and light. Under acidic pH conditions of admixtures the aminothiazole moiety of aztreonam was diazotized by the nitrite ion contributed by metronidazole solutions. The diazotized molecule, in turn, reacted with another aztreonam molecule by diazo-coupling. The resultant pink-colored product was isolated by chromatography and its structure was determined by mass spectral and NMR analyses. Other β-lactam antibiotics containing the 2-aminothiazole moiety also react in acidic media in a similar manner. [ABSTRACT FROM AUTHOR]

• Video of color formation process was recorded by smart phone. • Features were extracted from color formation process on TLC. • Appropriate color space for feature representation was established. • Structures of representative bioactives were classified in color space. With booming of computer technology, it is feasible to quantitatively extract valuable information from readily available image of objects, which dramatically reduces the cost and improves the efficiency. In this work, a structural classification method, based on data extracted from color formation process on thin layer chromatography (TLC) plates through computer processing, was established for natural products. Representative natural products exhibited good clustering and separation according to the extracted color feature, and structure of natural products can be classified by the distribution region in the color system. This method provides structural information for typical types of natural products directly from the formed color on TLC, which is very efficient and make portable device-based structure analysis of natural products possible. In addition, a general mechanism of color formation was proposed. This method is free from special instrument, high-throughput, and would facilitate large-scale screening of bioactives from natural sources. [ABSTRACT FROM AUTHOR]

Purple pakchoi (Brassica rapa ssp. Chinensis) is particularly appreciated due to its high edible quality and ornamental value, but there are few studies on the underlying mechanisms of leaf color formation. To comprehensively assess the differences in purple formation in pakchoi, four lines of pakchoi with different purple leaves were used in this experiment to determine the pigment content and to investigate the distribution and components of anthocyanin using LCMS (Liquid Chromatography Mass Spectrometry) and leaf cross-sections. Moreover, the expression levels of anthocyanin synthesis-related genes in four lines were calculated by qRT-PCR. The results showed that three new purple lines rich in anthocyanin and of high-quality were bred, and the anthocyanin were mainly distributed in both the upper epidermis and lower epidermis of leaves. Thirteen anthocyanin components were separated and identified, all the anthocyanins were acylated and glycosylated cyanidins; the main anthocyanins in purple pakchoi were a diacylated form of cyanidin 3-trans-(feruloyl)diglucoside-5-(malonyl)glucoside. Both the ratio of non-aromatic acylated cyanidin to aromatic acylated cyanidin and the ratio of anthocyanin content to chlorophyll content were responsible for the color formation in different purple pakchoi lines. When the ratio was high, the leaf appeared reddish purple, and when the ratio was low, the leaf appeared deep purple, even blackish purple. The expression level of BrF3H was significantly correlated with the content of anthocyanin through the correlation coefficient, which was speculated to be the main anthocyanin synthesis-related gene resulting in color differences among the four purple pakchoi lines. These results will enhance our understanding for the cultivation of new purple pakchoi varieties. [ABSTRACT FROM AUTHOR]

In this study, the Maillard reaction of maltose and d-glucose in the presence of l-alanine was investigated in aqueous solution at 130 °C and pH 5. The reactivity of both carbohydrates was compared in regards of their degradation, browning, and antioxidant activity. In order to identify relevant differences in the reaction pathways, the concentrations of selected intermediates such as 1,2-dicarbonyl compounds, furans, furanones, and pyranones were determined. It was found, that the degradation of maltose predominantly yields 1,2-dicarbonyls that still carry a glucosyl moiety and thus subsequent reactions to HMF, furfural, and 2-acetylfuran are favored due to the elimination of d-glucose, which is an excellent leaving group in aqueous solution. Consequently, higher amounts of these heterocycles are formed from maltose. 3-deoxyglucosone and 3-deoxygalactosone represent the only relevant C 6 -1,2-dicarbonyls in maltose incubations and are produced in nearly equimolar amounts during the first 60 min of heating as byproducts of the HMF formation.

Lactuca sativa var. capitate (iceberg lettuce) is a delicious vegetable and popular for its mild taste. Nevertheless, iceberg lettuce is a source of bitter substances, such as the sesquiterpene lactones. Chemical investigations on the n-butanol extract led to the isolation of three novel sesquiterpene lactones. All compounds were isolated by multilayer countercurrent chromatography followed by preparative high-performance liquid chromatography. The structures were verified by means of spectroscopic methods, including NMR and mass spectrometry techniques. For the first time 11ß,13-dihydrolactucin-8-O-sulfate (jaquinelin-8-O-sulfate) was structurally elucidated and identified in plants. In addition, the sesquiterpene lactones cichorioside B and 8-deacetylmatricarin-8-O-sulfate were identified as novel ingredients of iceberg lettuce. Further flowering plants in the daisy family Asteraceae were examined for the above three compounds. At least one of the compounds was identified in nine plants. The comparison between the lettuce butt end and the leaves of five types of the Cichorieae tribe showed an accumulation of the compounds in the butt end. Further experiments addressed the impact of sesquiterpene lactones on color formation and bitter taste.