Tea Pigments Research Articles

Effects of Fermentation Temperature and Time on the Color Attributes and Tea Pigments of Yunnan Congou Black Tea.

Yunnan Congou black tea (YCBT) is a typical black tea in China, and is rich in theaflavins (TFs), thearubigins (TRs), and theabrownins (TBs). However, the influence of the fermentation temperature and time on the liquor and appearance color and the correlation between the tea pigments and its color attributes remain unclear. We investigated the effects of the fermentation temperature and time on the color attributes and tea pigments of YCBT. A low fermentation temperature was beneficial to maintain a bright orange-red liquor color and promote the accumulation of TFs and TRs. In contrast, a high temperature gave the liquor a glossy appearance and was beneficial for the formation of TBs. A correlation analysis showed that the 10TFRB index best represented the contribution of tea pigments to the quality of black tea. Moreover, TRs and TBs content prediction models were established based on the liquor L and H values, where the former value can be used as an important index to judge the fermentation process. This study will further enrich the theory of black tea processing chemistry and provide technical support for the precise and directional production of black tea.

Enzymatic treatment in black tea manufacturing processing: Impact on bioactive compounds, quality, and bioactivities of black tea

This study investigated the changes of main quality components and the effect of bioactivities of black tea during a manufacturing process that adds to enzymatic treatment. It used black tea harvests in summer and autumn for manufacturing and analyzed the number of main quality components and bioactivities of the black tea produced by treating cellulase during rolling and polyphenol oxidase (PPO) and peroxidase (POD) during fermentation. The results found that the contents of total catechins (TC), total polyphenols (TP), reducing sugars (ReS), and individual catechins in the tea infusions of summer and autumn black tea that were obtained during enzymatic treatments decreased significantly (p < 0.05). However, the content of free amino acid (FAA), the tea quality parameter such as the total liquor color (TLC), the briskness index (BI), and the tea pigments including total theaflavin (TF), thearubigens (TR), TRSI, and TRSII all increased significantly (p < 0.05). Moreover, the biological activity enhanced black tea's antioxidant and metabolic capacity with enzymatic treatments were proved by in vitro experiments. The results of this study contribute to gaining further knowledge on how black tea's quality and potential health benefits are maximized by using exogenous enzyme addition methods in the manufacturing process preparation.

Chromatographic Determination of the Mycotoxin Patulin in 219 Chinese Tea Samples and Implications for Human Health.

Patulin (PAT) is a mycotoxin, with several acute, chronic, and cellular level toxic effects, produced by various fungi. A limit for PAT in food of has been set by authorities to guarantee food safety. Research on PAT in tea has been very limited although tea is the second largest beverage in the world. In this paper, HPLC−DAD and GC−MS methods for analysis of PAT in different tea products, such as non-fermented (green tea), partially fermented (oolong tea, white tea, yellow tea), completely fermented (black tea), and post-fermented (dark tea and Pu-erh tea) teas were developed. The methods showed good selectivity with regard to tea pigments and 5-hydroxymethylfurfural (5-HMF) and a recovery of 90–102% for PAT at a 10–100 ppb spiking level. Limit of detection (LOD) and limit of quantification (LOQ) in tea were 1.5 ng/g and 5.0 ng/g for HPLC−UV, and 0.25 ng/g and 0.83 ng/g for GC−MS. HPLC was simpler and more robust, while GC−MS showed higher sensitivity and selectivity. GC−MS was used to validate the HPLC−UV method and prove its accuracy. The PAT content of 219 Chinese tea samples was investigated. Most tea samples contained less than 10 ng/g, ten more than 10 ng/g and two more than 50 ng/g. The results imply that tea products in China are safe with regard to their PAT content. Even an extreme daily consumption of 25 g of the tea with the highest PAT content (124 ng/g), translates to an intake of only 3 μg/person/day, which is still an order of magnitude below the maximum allowed daily intake of 30 µg for an adult.

Preparation of instant dark tea by liquid-state fermentation using sequential inoculation with Eurotium cristatum and Aspergillus niger: Processes optimization, physiochemical characteristics and antioxidant activity

Preparation of instant dark tea (IDT) by liquid-state fermentation (LF) is an effective procedure, of which the process is more easily controlled than solid-state fermentation (SSF). The present study focused on developing a sequential inoculation liquid-state fermentation (SILF) procedure using the Eurotium cristatum and Aspergillus niger to prepare IDT. The key parameters (turbidity, redness, and tea pigments) were optimized by response surface methodology (RSM). Optimum conditions were modeled to be a water-tea ratio of 24.0 mL/g, inoculum size of 8.7% (v/v), and time of 9 d. The predicted and experimental values of redness, turbidity and tea pigments content were within a 5% difference using the optimized conditions. Bench scale was achieved in a 5-L fermenter, which generated IDT with a redness value of 43.50, a turbidity of 5.67 NTU and tea pigments content of 23.53%, w/w. The evaluation by E-nose and E-tongue showed that IDT had a similar aroma and mouthfeel with a commercial instant Fu-brick tea (IFT), and the antioxidant activities in vitro, color and clarity of tea infusion of IDT were higher than those of the IFT, respectively. These results indicate that preparation of IDT by SILF is feasible, this work expect to set up a new aspect for preparation of IDT.

Evaluation of Volatile Profile and In Vitro Antioxidant Activity of Fermented Green Tea Infusion With Pleurotus sajor-caju (Oyster Mushroom).

Green tea has distinct astringency, bitter taste, and typical green flavor because of its post-harvest treatment without withering and enzymatic oxidation. Microbial fermentation has been identified as a promising strategy that could give green tea infusion a special taste flavor. This might be linked to the metabolic transformation ability of microorganisms. In this study, starter culture of edible mushroom Pleurotus sajor-caju (oyster mushroom) was used for submerged fermentation of green tea infusion in order to improve its flavor and taste quality. The volatile profile determined by headspace solid-phase microextraction, coupled with gas chromatography mass spectrometry, showed that the contents of (Z)-2-penten-1-ol and methyl heptadienone in green tea infusion were decreased significantly by the fermentation with the basidiomycete P. sajor-caju (p < 0.01), which would alleviate the herbal and grass flavor of green tea infusion to a certain extent. Meanwhile, the contents of linalool and geraniol were increased 9.3 and 11.3 times, respectively, whereas methyl salicylate was newly produced after fermentation by P. sajor-caju, endowing the fermented tea infusion with a pleasant flower and fruit aroma. In addition, the polyphenol profile was determined using high-performance liquid chromatography equipped with ion trap mass spectrometry, and the results indicated that the contents of most polyphenols in green tea infusion decreased significantly after fermentation by P. sajor-caju. The reduction of catechins and anthocyanins in fermented green tea infusion alleviated the astringency and bitterness. Moreover, the antioxidant activity of fermented green tea infusion was obviously decreased, especially the DPPH-free radical-scavenging ability and the ferric-reducing power. However, it is noteworthy that the ABTS-free radical scavenging ability was improved compared with the unfermented one, indicating that the increased tea pigments and volatile metabolites (such as linalool and geraniol) after fermentation with P. sajor-caju may also contribute to the antioxidant capacity of fermented green tea infusion. Overall, the innovative approach driven by P. sajor-caju fermentation has achieved promising potential to manipulate the green tea flavor.

Creating antique effects on silk fabric

PurposeThe purpose of this study is to reduce the gloss of the surface of silk fabrics, by treating the fabrics with tea and matting agent, to imitate the aging and retro effects of silk artefacts.Design/methodology/approachSilk fabrics were treated with different processing techniques. The aged appearance and surface gloss of the silk fabrics were characterised by sensory analysis, measurement of reflectivity, scanning electron microscopy, measurement of brightness and chroma to identify the influential factors.FindingsThe application of matting agent on silk fabrics could reduce the lustre of silk fabrics. Treated with matting agent and tea pigments, silk fabrics could be “aged” to achieve retro effects within a relatively short period of time. A number of other factors and mechanisms that affect the reflectivity of the silk fabrics were also identified.Research limitations/implicationsThere is no definite index to evaluate the antique effect of fabrics.Practical implicationsThe method developed through this study provided a simple and practical solution to achieving aging and retro effects on silk fabrics.Originality/valueThe method for reducing the lustre of silk fabrics by treating them with matting agent is novel and the finding of the relationships among reflectivity and brightness and chroma is original.

Effect of microbial fermentation on the sensory characteristics and chemical compositions of Chinese sweet tea (Lithocarpus litseifolius (Hance) Chun)

Sweet tea, which has hundreds of years of use among in Chinese folk, is a traditional herbal tea with pleasant sweetness, bitterness and astringency. In the current study, we used traditional microbial fermentation to improve sensory characteristics of sweet tea, especially for the reduction of bitterness and astringency. The dynamic changes of non-volatile, volatile compounds and microbial community were investigated during microbial fermentation. The contents of polyphenols, flavonoids, soluble sugar, soluble protein, catechins and dihydrochalcones decreased significantly while the tea pigments, free amino acids and gallic acid content inversely increased during microbial fermentation. A total of 61 volatile compounds were identified and quantified in sweet tea, of which 20 key compounds were identified as odor active compounds (OAV), including 3 aldehydes, 1 ketone, 4 alcohols, 9 esters, 4 alkenes and 3 other compounds. In addition, eight fungi and four bacteria were considered as core microorganisms, such as Aspergillus, Alternaria, Cladosporium, Epicoccum, Itersonilia, Penicillium, Periconia, Wallemia, Aureimonas, Enterobacter, Klebsiella and Stenotrophomonas, which were significantly correlated with non-volatile compounds and flavor compounds. These results provided theoretical guidance for processing of fermented sweet tea.

Anticancer Effects and Molecular Target of Theaflavins from Black Tea Fermentation in Vitro and in Vivo.

Black tea is one of the most popular beverages in the world, and numerous epidemiological studies have shown that drinking black tea is good for health. As a natural tea pigment formed during the fermentation of black tea, the content of theaflavins accounts for only 2-6% of the dry weight of black tea, but they have a great impact on the color and taste of black tea soup. Recently, a large number of studies have shown that theaflavins have a significant anticancer effect. In this Perspective, we first state the physical and chemical properties, separation and purification methods, and biological formation pathways of theaflavins and analyze their safety and oral bioavailability and the structure-activity relationship of their antioxidant and anticancer activities; then, we describe in detail their anticancer effect in vitro and in vivo and highlight their various molecular targets involved in cancer inhibition. The anticancer molecular targets of theaflavins are mainly cell-cycle regulatory proteins, apoptosis-related proteins, cell-migration-related proteins, and growth transcription factors. Finally, the possibility of developing new health-care food based on theaflavins is discussed. This Perspective is expected to provide a theoretical basis for the anticancer application of theaflavins in the future.

New insights into the effect of fermentation temperature and duration on catechins conversion and formation of tea pigments and theasinensins in black tea.

The phenol oxidative pathway during fermentation remains unclear. To elucidate the effect of fermentation on phenol conversion, we investigated the effects of fermentation temperature and duration on the conversion of catechins and the formation of theasinensins (TSs), theaflavins (TFs), thearubigins (TRs), and theabrownins (TBs). During fermentation, TSs formation increased initially and then decreased. Long fermentation durations were unfavorable for liquor brightness (LB) and resulted in the production of large amounts of TRs and TBs. Low fermentation temperatures (20 °C and 25 °C) favored the maintenance of polyphenol oxidase activity and the continuous formation of TFs, TSs, and TRSI (a TRs fraction), resulting in better LB and liquor color. Higher temperatures (30 °C, 35 °C, and 40 °C) resulted in higher peroxidase activity, higher oxidative depletion rates of catechins, and excessive production of TRSII (a TRs fraction) and TBs. Analysis of the conversion pathway of polyphenolic compounds during fermentation showed that, during early fermentation, large amounts of catechins were oxidized and converted to TFs and theasinensin B. As fermentation progressed, considerable amounts of theaflavin-3'-gallate, theasinensin A, theaflavin-3-gallate, theaflavin-3,3'-digallate, and theasinensin C were produced and then converted to TRSI; in the final stage, TRSII and TBs were converted continuously. Different fermentation temperature and duration combinations directly affected the type and composition of phenolic compounds. The key conditions for controlling phenolic compound conversion and fermentation direction were 60 or 90 min and 25 or 30 °C. Our study provides insights into the regulation of phenolic compound conversion during black tea fermentation. © 2021 Society of Chemical Industry.

New degradation mechanism of black tea pigment theaflavin involving condensation with epigallocatechin-3-O-gallate

Theanaphthoquinone (TNQ) is the initial and main oxidation product of theaflavin, a representative black tea pigment. Nevertheless, TNQ is virtually undetected in the high-performance liquid chromatography analysis of black tea leaves using photodiode array detection. To elucidate the degradation mechanism of theaflavin in the black tea production process, this study investigated the reaction of TNQ with epigallocatechin-3-O-gallate (EGCg), which is the most abundant polyphenol in tea leaves. In citrate–phosphate buffer solution at pH 6 and room temperature, TNQ reacted nonenzymatically with EGCg to afford three products, whose structures were determined on the basis of spectroscopic data. The results indicated that the double bond of the ortho-naphthoquinone moiety in TNQ reacted with the autoxidation product of EGCg. This study demonstrates novel reactions occurring in the process of theaflavin degradation, which might be involved in the formation of thearubigins, the major black tea pigments composing oligomeric catechin oxidation products.

Effect of trans retinoic acid on patients with oral submucous fibrosis-randomized single-blind monocentric study.

Various treatment modalities have been practiced for the suppression of premalignant conditions such as oral submucous fibrosis (OSMF) to prevent their differentiation into malignant lesions. Conventional treatment includes steroids, enzymes like hyaluronidase, trypsin, chymotrypsin and placental extracts which are advocated intralesionally and oral drugs like carotenoids, alpha lipoic acid, lycopene, vitamins, microelements and tea pigments have also been advocated.In this study, a total number of 30 patients with OSMF were taken and randomly divided into two groups with 15 patients each according to Khanna and Andrade group of classification 1995. Group 1 (test group) received the test drug Tretiome 20 mg, whereas Group 2 (control group) received an antioxidant lycopene 20 mg/day for a period of 1 month and the effect of the therapy with the changes in the symptoms was recorded every 1 week, 15 days and 30 days of follow-up. The result of this study showed an improvement in the mouth opening of the patients of test Group with a significant decrease in the burning sensation as compared to the control group (P < 0.05). Xerostomia and headache were the two most commonly seen side effects which were reported in the patients of the test group, of which headache was associated with the withdrawal symptom of habit cessation and xerostomia was taken care by increase in hydration.

WITHDRAWN: The Influence of tea pigment on the properties of hydroxypropylmethylcellulose for curing artificial tears (AT) of animal eye

This work aims to study the Influences of tea pigment on the properties of Hydroxypropylmethelcellelose HPMC. Two solutions were prepared; one of them involve: dissolved 0.3 of HPMC in 50 ml of double distillation water with constant stirring via a magnetic mixer. The material will clump and then heated to 80° C until it becomes viscous, cooled and leave disparately for 30 min. Different tests were carried out, such as Osmosmality, cured animal, rheology, zeta potential, density, PH and FTIR. Findings demonstrated that the preservative material acts as a cationic surfactant and as a biocide agent and causes Influences, such as decreasing the oscillatory from 287 to 283 Osm/L, from 6.6 to 6.44, increasing the zeta potential from −20 to −31 mV and mobility from −1.8 to −2.1 (m/s)/(V/cm). From the viewpoint of rheology characteristics, benzalkonium chloride addition makes the viscosity–shear rate relation closer to the standard tear behaviour with shear thinning behaviour.

Tea bioactive components prevent carcinogenesis via anti-pathogen, anti-inflammation, and cell survival pathways.

Cancer seriously impairs human health and survival. Many perturbations, such as increased oxidative stress, pathogen infection, and inflammation, promote the accumulation of DNA mutations, and ultimately lead to carcinogenesis. Tea is one of the most highly consumed beverages worldwide and has been linked to improvements in human health. Tea contains many active components, including tea polyphenols, tea polysaccharides, L-theanine, tea pigments, and caffeine among other common components. Several studies have identified components in tea that can directly or indirectly reduce carcinogenesis with some being used in a clinical setting. Many previous studies, in vitro and in vivo, have focused on the mechanisms that functional components of tea utilized to protect against cancer. One particular mechanism that has been well described is an improvement in antioxidant capacity seen with tea consumption. However, other mechanisms, including anti-pathogen, anti-inflammation and alterations in cell survival pathways, are also involved. The current review focuses on these anti-cancer mechanisms. This will be beneficial for clinical utilization of tea components in preventing and treating cancer in the future.

Effects of novel fermentation method on the biochemical components change and quality formation of Congou black tea

This study aimed to investigate the effects of a novel dynamic fermentation method (DFM) on the biochemical components change and sensory quality formation of Congou black tea. It was found that the most drastic changes in biochemical components took place within 30 min of fermentation. The a value (redness) of liquor color, the reduction degree of catechins, polyphenol oxidase activity, the formation rate and contents of theaflavins and thearubigins, as well the content of amino acids were significantly higher under DFM than the traditional fermentation method. Sensory quality was also superior under DFM with the highest scores for liquor color, aroma, and taste. Partial least squares discrimination analysis (PLS-DA) indicated significant differences between DFM and the other two methods. Moreover, the loadings scatter plot and variables important in the projection (VIP) showed that amino acids, catechins, and tea pigments were the key differential substances among the fermentation methods. These results are expected to provide a theoretical basis and technical guidance for the improvement of black tea quality.

Microbiological and technological parameters impacting the chemical composition and sensory quality of kombucha.

Kombucha is a beverage made from sugared tea transformed by yeasts and acetic acid bacteria. Being originally homemade, it has become an industrially produced soft drink whose quality standards are poorly defined and whose production process is still not fully controlled. Based on current knowledge in beverages, links between kombucha's chemical composition and sensorial compounds are drawn. Macromolecules create turbidity, whereas uncharacterized tea pigments derivatives participate in the color. Residual sugars bring sweetness and organic acids produced by acetic acid bacteria form its characteristic sour taste. Acetic acid is also part of its aroma profile, although little data are available on the smell of kombucha. Carbon dioxide, potentially polyphenols, and residual ethanol are involved in the mouthfeel. In this review, after defining the key compounds that shape the characteristic sensory properties of kombucha, the impact of different production parameters is discussed. Water composition is determinant in the extraction of tea compounds along with the tea type and infusion duration and temperature. The type and amount of sweeteners play a role in the sweetness and influences the production kinetics. Similarly, the amount of inoculum and its microbial composition have an effect on the production, but the role of the vessels' geometry and temperature are also essential parameters that can be used to adjust the acidification phase's duration. Despite the amount of research carried out, further investigations of kombucha's sensory characteristics are needed. Such research could lead to a better definition of kombucha's quality and to an improved control over its production process.

A high‐precision method evaluating color quality of Sichuan Dark Tea based on colorimeter combined with multi‐layer perceptron

AbstractInstrumental examination of Sichuan Dark Tea (SDT) quality instead of human panel sensory evaluation is important for quality control. This study attempted to create a high‐precision method to rapidly and accurately evaluate SDT color quality. Colorimeter combined with multi‐layer perceptron (MLP) was utilized to extract CIELAB color parameters of dried tea, liquor, and infused tea, respectively, and established the prediction models of color attributes scores with the optimal color parameters selected by a principal component analysis (PCA). MLP models established could accurately predict color total scores of SDT, the glossiness of dried tea, and chroma of infused tea (Rp = 0.889–0.989; RMSEP = 0.393–0.631). Besides, models based on tea pigments could accurately predict infused tea color total scores (Rp = 0.920, RMSEP = 0.531). Parameter a* was significantly correlated with almost all of the color evaluation factors of SDT and seemed to be the characteristic color parameter. The color quality of Sichuan Dark Tea can be excellently estimated by the method utilizing colorimeter coupled with MLP.Practical applicationsTo meet the requirement of dark tea production and the costumer's expectation, this study attempted to create a high‐precision method quickly and accurately evaluating color quality of SDT. Usually, in the massive production, tea color evaluated by eyesight is time‐consuming, subjective, and has poor accuracy due to visual fatigue of human. In this work, we optimized color parameters with PCA to improve the performance of MLP models established. The results can provide a theoretical basis for the evaluation of tea color quality by instrument, and make SDT quality control more convenient, accurate, and time‐saving.

Dyeing cotton with tea extract based on in-situ polymerization: An innovative mechanism of coloring cellulose fibers by industrial crop pigments

Deep exploitation and utilization of industrial crops are becoming an efficient path to wrestle with the excessive consumption of non-renewable resources. In this research, a novel dyeing mechanism for cellulose fibers with tea pigments based on in-situ polymerization was developed. The pad-steam process was adopted to realize the coloration and fixation of tea pigments onto cotton fabric without using mordant. The optimal concentration of NaOH solution was determined to be 1.2 g/L. The effectiveness and advancement of this novel dyeing method were proved by the dyeing effect, washing color fastness and FTIR spectra. Dyed cotton fabric possessed soft color, good color fastness, as well as satisfactory antibacterial activity against Staphylococcus aureus and Escherichia coli. This research provided an innovative method for tea extract to simultaneously endow cotton with color and functionality without using chemical mordants, which was possessed of universal applicability for many kinds of industrial crops.

How black tea pigment theaflavin dyes chicken eggs: Binding affinity study of theaflavin with ovalbumin

Theaflavin (TF), which is the key pigment in black tea, is a health-promoting food component with beneficial effects on humans. However, the interactions by which these effects are transferred and exerted into protein-rich foods are unclear. Here, egg ovalbumin (OVA) was selected as a representative dietary protein to ascertain their binding mechanism. Steady-state, time-resolved fluorescence and isothermal titration calorimetric results showed that TF can interact well with OVA with an affinity magnitude of 104. The noncovalent binding was mainly driven by hydrophobic interaction and hydrogen bonds. Structural analysis displayed that the TF binding pocket significantly overlapped with one of the surrounding specific IgE-binding epitopes, thereby causing a subtle structural adjustment on the secondary conformation of OVA. The biological complexation model that was delineated here will help understand how black tea dyes egg white in tea egg products and for the development of protein-rich carriers in functional foods.

Analysis of Natural Mordant to B. mori Silk Fabrics Dyeing with Tea Extract

Tea pigments as biological materials were extracted in this paper. Applications of turmeric and tannic acid during the silk dyeing with tea extract were studied. By changing mordant dyeing methods, concentration of mordant, dye solution pH value and dyeing concentration, we tried to study the effect of natural mordant. The results showed that two kinds of mordant were more suitable for pre-mordant. When the tannic acid was 5 g/L, the turmeric was 0.025 g/L, and the dye solution pH value was 5, the dyeing effect was optimal. Furthermore, when the dyeing concentration was diluted 5 times, the dyed fabric color was fuller. With the optimum mordant dyeing process conditions, the colors fastness to washing were acceptable.

Application of machine learning algorithms in quality assurance of fermentation process of black tea-- based on electrical properties

Fermentation process directly determines the product quality of black tea. This work aimed to develop a rapid method for detecting the degree of fermentation of black tea based on electrical properties of tea leaves. An LCR meter employed to identify 11 electrical parameters of tea leaves during the fermentation process, and the content of catechins and tea pigments in tea leaves were measured by using HPLC and UV-Vis spectrometer, respectively. Principal component analysis and hierarchical clustering analysis applied to divide samples into different groups in the degree of fermentation. Correlation analysis used to characterize the responding strength of electrical parameters on the variation of catechins and pigments. Finally, multilayer perceptron, random forest, and support vector machine algorithm used to build discrimination models of fermentation degree, and the average accuracy rate on the testing set reached to 88.90%, 100%, and 76.92%, respectively.