Black Tea Extract Research Articles

Health risk assessment of heavy metals in black tea infusion by Monte Carlo simulation

AbstractTea leaves and their infusion have been interested in the populations because of their therapeutic and relaxing effects. However, tea plant is prone to heavy metals' bioaccumulation. Regarding the high consumption of tea infusion, concentration of arsenic, cadmium, and lead in black tea infusion was determined by inductively coupled plasma mass spectrometry. Tea infusion was prepared by addition of 45 mL deionized water to 1 g tea leaves followed by heating at 90°C for 10 min. After analysis, carcinogenic and noncarcinogenic risks of heavy metals were investigated by Monte Carlo simulation in two age groups of children and adults younger and older than 15 years old, respectively. According to the results, Hazard Quotient (HQ) of three heavy metals in both children and adults was equal and lower than 0.01. Furthermore, incremental lifetime cancer risk (ILCR) of arsenic in Iranian black tea consumers (<1.5 × 10−6) and lead in all consumers (about 2.55 × 10−7) was within the acceptable range introduced by US EPA (≤10−6). ILCR of arsenic in children and adults consuming foreign tea infusion was within the range of 10−6–10−4. Our further investigation revealed that the highest area (75%–85%) of cumulative frequency distribution for arsenic ILCR in foreign tea consumers was related to ILCR ≤10−5 which is the acceptable range determined by the World Health Organization. Therefore, there was no serious concern about the intake of heavy metals by tea infusion in Iranian children and adults.

Biosensor Based on the Immobilization of Laccase on β-Cyclodextrin Membrane for the Evaluation of Antioxidant Capacity in Real Samples.

The optimization of a new amperometric biosensor for evaluating antioxidant capacity in real samples is reported. The biosensor is based on the immobilization of Laccase from Trametes versicolor on an electropolymerized β-cyclodextrin polymeric membrane on a glassy carbon electrode. The process of electropolymerization, which was successful even in the presence of the enzyme, was a key step in biosensor synthesis. Variables such as pH, temperature, and enzyme concentration were optimized using a factorial design with two levels for each factor. Different electrodes were constructed and tested using caffeic acid as a standard. The best biosensor is synthesized at pH 3.0 with 6 mg/mL of enzyme and 30 °C. The biosensor presented a response time of ≤30 seconds and good stability in its amperometric response. The biosensor was used to evaluate the antioxidant capacity of real samples. Infusions of green, black, red, and white tea were assessed. The biosensor showed excellent stability and good performance regarding response time, stability, and easy fabrication. The proposed biosensor is a good option for evaluating antioxidant capacity in real samples without sample pretreatment. It combines a simple fabrication methodology and a minimal extraction process for rapid and reliable phenolic content determination in real samples.

Effect of green tea or black tea extract on lipid and protein oxidation in Cantonese sausage.

Natural polyphenols offer a safer alternative to synthetic antioxidants in meat products. This study investigated the efficacy of green tea and black tea extracts as natural antioxidants in Cantonese sausages to inhibit lipid and protein oxidation. Sausages were prepared with the addition of different concentrations - 100, 300, and 600 mg kg-1 total polyphenols (TP) - of green tea or black tea extract. Oxidation of the sausages was assessed through thiobarbituric acid reactants, carbonyl content, and thiol content, whereas consumer acceptability was evaluated based on texture, color, and sensory analysis. The tea extracts inhibited malondialdehyde production and reduced the thiobarbituric acid reactive substance value from 23.72 mmol MDA g-1 to less than 1.94 mmol MDA g-1. However, the addition of tea extracts decreased the thiol content and caused the loss of myosin heavy chain and actin bonds in sodium dodecyl sulfate polyacrylamide gel electrophoresis. Although the addition of tea extracts increased the redness and hardness of the sausage, no significant difference in consumer acceptance between the control and treatment groups was observed in the sensory analysis. The tea extract inhibited the oxidation of lipids in Cantonese sausage. There was no negative effect on the sensory characteristics of sausages. The use of tea extracts as natural antioxidants in Cantonese sausage is therefore feasible. © 2024 Society of Chemical Industry.

ECONOMIC FEASIBILITY STUDY FOR THE IMPLEMENTATION OF A MICRO-INDUSTRY PRODUCING KOMBUCHA FLAVORED WITH PASSION FRUIT FROM THE CAATINGA.

Kombucha is a fermented beverage of Chinese origin produced from the infusion of black or green tea from the Camelia sinensis plant, sugar and a symbiotic culture known as SCOBY. After fermentation, the drink becomes rich in natural nutrients with functions that are beneficial to health such as organic acids, amino acids, vitamin C, polyphenols and antibiotic substances. The present work aims at carrying out a study of the economic feasibility of opening a micro-industry for the production of a black tea kombucha flavored with passion fruit from the caatinga. The caatinga passion fruit is a species native to the dry areas of northeastern Brazil. This fruit is rich in flavonoids, vitamin C and carotenoids, which have antimicrobial and antioxidant properties. For the development of the study, specifications of processes, equipment and analysis of financial and economic indicators were carried out. The evaluation of the investments was carried out using the internal rate of return (IRR), minimum attractiveness rate (TAM), net present value (NPV), simple payback and discounted payback methods. The initial investment for the production of 2,000 L of kombucha flavored with passion fruit from the caatinga was R$ 187,199.78. The economic indicators obtained resulted in NPV of R$ 253,154.68, IRR of 22%, TAM of 13.34% p.a. and simple payback of 3.9 years considering a useful life of 10 years. The positive IRR reflects that the enterprise is economically viable and profitable, making it possible to invest and generate income for cooperatives and family farmers.

Optimization of Ecofriendly L-Fe/Ni Nanoparticles prepared using extract of black tea leaves for Removal of tetracycline antibiotics from Groundwater by Response Surface Methodology

This article focuses on employment of nanotechnologies in remediation of tetracycline antibiotics (TC) from groundwater by green synthesized bimetallic Fe/Ni supported by limestone particles. An in-situ green synthesis nanoparticles was prepared using black tea leaves extract to generate a L-Fe/Ni nanocomposite. The synthesized nanocomposite was characterized using several techniques, such as, X-Ray Diffraction (XRD), Scanning Electron microscopy (SEM), transmission electron microscope (TEM), Energy dispersive X-ray (EDX), FTIR (Fourier Transform-Infra Red) spectroscopy and surface area. We then use response surface methodology (RSM) to optimize the synthesis process and evaluate the effectiveness of the prepared nanocomposite for tetracycline remediation. We took different simulated concentrations of the TC contaminant without relying on actual TC concentrations in grounwater, the best removal of the TC contaminant in batch study was investigated with relying on the initial concentrations of TC and other experimental factors such as pH, adsorbent nanomaterial concentration and time. A pilot plant was then constructed to eliminate the TC contaminant from groundwater in different concentrations, where the removal efficiency was found decreased with increasing in the concentration of the TC Many parameters affecting the removal mechanisms in statistical and continuous systems were examined to select the best results that accomplish the maximum elimination rate. With the improved operating conditions, (L-Fe/Ni concentration: 1500 mg/L; concentration of TC: 20 mg/L; pH: 7.2; contact time: 128 min), removal percent of TC was found 87 % based on RSM system. The L-Fe/Ni reactive medium of continuous column has a main role in slowing down the movement of the TC plume. This study showed that the ecofriendly nanocomposite could be an appropriate and novel method for remediation of antibiotics and other contaminants in groundwater.

Functional Properties and Sensory Quality of Kombucha Analogs Based on Herbal Infusions.

Traditionally, kombucha is produced by the fermentation of black or green tea infusions with the use of SCOBY (Symbiotic Culture of Bacteria and Yeasts). However, SCOBY exhibits the ability to ferment other substrates as well, which can be used to create novel products with new sensory and health-promoting properties. This paper investigates the antioxidant activity, chemical composition, and sensory properties of mint, nettle, and blackcurrant leaf-based kombucha analogs. It has been demonstrated that the fermentation process with SCOBY significantly influenced (p ≤ 0.05) sugar, organic acids, and mineral contents, with the increase in iron, magnesium, and calcium amounts in all tested herbal kombucha. The study shows that the type of herb infusion has a significant influence on the parameters associated with antioxidant potential. The fermentation with SCOBY resulted in an increase in antioxidant activity as measured by the superoxide anion radical (O2•-) inhibition of all three tested herbal infusions, with the greatest changes observed in nettle kombucha. Herbal kombucha was characterized by significantly increased total phenolic content as determined by Folin's reagent and a changed phenolic compound profile by LC-MS/MS (liquid chromatography with tandem mass spectrometry) in comparison to nonfermented infusions. Very high sensory scores were achieved for fermented mint and blackcurrant-based kombucha.

Quality attributes of black tea-flavored Chardonnay wine processed by ultrasound

An innovative Chardonnay wine flavored with black tea was prepared under optimal ultrasound conditions at 450.0 W for 22.6 min, and its physicochemical features, antioxidant power, total phenolic content, and volatile composition were systematically examined. A total of 165 phenolic and non-phenolic substances were characterized, including 27 newly formed phenolic substances and 10 non-phenolic substances that were not found in both black tea and Chardonnay wine. Catechin was found to be the phenolic compound with the largest amount detected, which was responsible for the potentiated antioxidant activities. The wine exhibited a profile of 44 volatile compounds, with 13 volatiles as odor-active compounds. Black tea infusion resulted in a decline in fruity, fermented and spicy aromas, but an increase in green and citrus odors, while ultrasound processing further intensified these odors. This study anticipated that ultrasound technology could hold promise for crafting flavored wines with heightened functionalities and appealing flavor profiles.Graphical Ultrasound-assisted infusion of black tea potentiated the antioxidant activity and enriched the volatile and phenolic profiles of Chardonnay wine.

Carbonic anhydrase 2 mediates anti-obesity effects of black tea as thermogenic activator

Obesity is a metabolic disorder due to over-accumulation of adipose tissue and ultimately becomes a “disease”. Brown adipose tissue (BAT) thermogenesis and white adipose tissue (WAT) browning emerge as a potential strategy of anti-obesity by dissipating energy as heat. However, drugs based on adipose tissue thermogenesis have not been successfully approved yet. In current study, we found that black tea extract (BTE) obtained by patent-authorized manufacturing process prevented body weight gain as novel thermogenic activator with reduction of adiposity, improvement of adipose distribution, and glucose metabolism improvement in diet-induced obesity mice. Mechanismly, anti-obesity effect of BTE depends on promoting BAT thermogenesis and WAT browning with upregulation of uncoupling protein 1 (UCP1), especially visceral adipose tissue (VAT) with browning resistance. Specifically, utilizing in silico approach of network pharmacology and molecular docking, we identified carbonic anhydrase 2 (CA2) in nitrogen metabolism as anti-obesity target of BTE and further elucidated that protein kinase B (AKT) signaling pathway linked CA2 and UCP1. Meanwhile gut microbiota regulation may prompt the CA2-dependent thermogenesis activation. Our findings demonstrated anti-obesity effect of BTE as thermogenic activator through CA2-mediated BAT thermogenesis and WAT browning via CA2-AKT-UCP1 signaling pathway, which could be developed as promising anti-obesity agent with good safety and efficacy.

Exploration of the prebiotic potential of black tea infusion powder on the human gut microbiota in vitro

Black tea is well known for its health-promoting properties, which are mostly attributed to its polyphenol content. Black tea polyphenols are mostly non absorbable and thus readily reach the colon, where they come in contact with the gut microbiota. Several gut microbial species are able to metabolize these polyphenols, which results in bioactive metabolites on the one hand and alterations in microbial community composition on the other. To date, most studies regarding the impact of black tea on the gut microbiota have used a limited set of endpoints. In this study, a more detailed view on the potential prebiotic effects of black tea was generated. The impact of black tea infusion powder on the composition and activity of the human gut microbiota was compared to that of inulin, by applying both products in the Mucosal Simulator of the Human Intestinal Microbial Ecosystem (M-SHIME®). The results indicated that black tea infusion powder increased acetate and butyrate production, though less than inulin. The black tea infusion powder also increased microbial diversity in most colon regions and stimulated several butyrate- and propionate-producing species, next to the well-known probiotic Bifidobacterium, as identified through metagenomic sequencing. In addition, the metabolic fingerprint of the gut microbiota was beneficially altered, compared to the control, especially by the black tea product. Finally, both the black tea infusion powder and inulin increased the gut microbiota's barrier strengthening properties. Together these results indicate that black tea infusion powder has the potential to function as a prebiotic in humans.

Pancreatic lipase immobilization on cellulose filter paper for inhibitors screening and network pharmacology study of anti-obesity mechanism

The discovery of pancreatic lipase (PL) inhibitors is an essential route to develop new anti-obesity drugs. In this experiment, chitosan was used to add amino groups to cellulose filter paper (CFP) and then glutaraldehyde was used to covalently combine PL with amino-modified CFP through the Schiff base reaction. Under optimal immobilization conditions, CFP immobilized PL has a wide range of pH and temperature tolerance, as well as excellent reproducibility, reusability and storage stability. Subsequently, 26 natural products (NPs) were screened by immobilized PL with black tea extract having the highest inhibition rate. Three compounds with binding effects on PL (epigallocatechin gallate, theaflavin-3-gallate and theaflavin-3,3′-digallate) were captured. Molecular docking proved that these three compounds have a strong binding affinity for PL. Fluorescence spectra further revealed that theaflavin-3,3′-digallate could statically quench the intrinsic fluorescence of pancreatic lipase. The molecular docking and thermodynamic parameters indicated that electrostatic interaction was considered as the main interaction force between PL and theaflavin-3,3′-digallate. Finally, the potential anti-obesity targets and pathways of the three compounds were discussed through network pharmacology. This study not only proposes a simple and efficient method for screening PL inhibitors, but also sheds light on the anti-obesity mechanism of active compounds in black tea.

Phytochemical and Organoleptic Tests of Combined Extracts of Turmeric, Black Tea, and Ginger

Phytochemical and Organoleptic Tests of Combined Extracts of Turmeric, Black Tea, and Ginger

Effects of biodegradation of starch-nanocellulose films incorporated with black tea extract on soil quality

This study aimed to investigate the biodegradation behaviour of starch/nanocellulose/black tea extract (SNBTE) films in a 30-day soil burial test. The SNBTE films were prepared by mixing commercial starch, nanocellulose (2, 4, and 6%), and an aqueous solution of black tea extract by a simple mixing and casting process. The chemical and morphological properties of the SNBTE films before and after biodegradation were characterized using the following analytical techniques such as field emission scanning electron microscopy (FESEM), energy-dispersive X-ray spectroscopy (EDX), and fourier transform infrared (FTIR). The changes in soil composition, namely pH, electrical conductivity (EC), moisture content, water holding capacity (WHC), soil respiration, total nitrogen, weight mean diameter (MDW), and geometric mean diameter (GMD), as a result of the biodegradation process, were also estimated. The results showed that the films exhibited considerable biodegradability (35–67%) within 30 days while increasing soil nutrients. The addition of black tea extract reduced the biodegradation rate due to its polyphenol content, which likely resulted in a reduction in microbial activity. The addition of nanocellulose (2–6% weight of starch) increased the tensile strength, but decreased the elongation at break of the films. These results suggest that starch nanocellulose and SNBTE films are not only biodegradable under soil conditions but also positively contribute to soil health, highlighting their potential as an environmentally friendly alternative to traditional plastic films in the packaging industry.

Extraction effects of eight deep eutectic solvents on dianhong black tea: From chemical composition analysis to antioxidant and α-glucosidase inhibitory assessments

Deep eutectic solvent (DES) has been widely developed and applied in extracting the functional components of teas, however, few studies devoted to revealing the composition differences of tea extracts obtained with DES. The present study aims to study the chemical composition and bioactive differences of Dianhong congou black tea extracts prepared by eight choline chloride (ChCl)-based DES. In addition, D-101 macroporous resin was used to remove DES for bioactivity analysis. High performance liquid chromatography (HPLC) and LC-mass spectrometry (LC-MS) were applied to quantitatively and qualitatively analyze chemical composition differences of DES extracts before and after DES removal. Quantitative results showed that DES4 (composed of ChCl and ethylene glycol) was suitable for extracting catechins (e.g., the extracted level of epicatechin gallate was 8.75 mg/g), theaflavins (theaflavin-3,3′-digallate, 1.59 mg/g), and monosaccharides (glucose, 4.97 mg/g), meanwhile DES5 (composed of ChCl and glycerol) was proved to be effective for extracting free amino acids (with highest level of theanine, 19.72 mg/g). LC-MS based metabolomics results showed that DES2 (ChCl-citric acid), DES3 (ChCl-proline), and DES4 had considerable remaining amounts of flavonoid glycosides, theasinensins, and hydrolysable tannins after DES removal. Although purified DES5 extract contained a comparable amount of these marker compounds to other purified DES extracts, its antioxidant and α-glucosidase inhibitory activities were the lowest among others. Combining results from above, DES4 was proved to be the optimum solvent for extracting functional components of Dianhong congou black tea. The finding provided basis for the application of DES extraction method in tea science.

Effects of Fermentation with Kombucha Symbiotic Culture of Bacteria and Yeasts on Antioxidant Activities, Bioactive Compounds and Sensory Indicators of Rhodiola rosea and Salvia miltiorrhiza Beverages.

Kombucha is a well-known fermented beverage traditionally made from black tea infusion. Recent studies have focused on finding alternative materials to create novel kombucha beverages with various health benefits. In this study, we prepared and evaluated two novel kombucha beverages using Rhodiola rosea and Salvia miltiorrhiza as materials. The effects of fermentation with the residue of these plants on the kombucha were also investigated. The antioxidant activities, total phenolic contents, and concentrations of the bioactive compounds of the kombucha beverages were determined by the Trolox equivalent antioxidant capacity test, ferric-reducing antioxidant power test, Folin-Ciocalteu method, and high-performance liquid chromatography, respectively. The results revealed that the kombucha beverages made with Rhodiola rosea and Salvia miltiorrhiza had strong antioxidant capacities and abundant phenolic contents. Additionally, the kombucha fermented with Rhodiola rosea residue had higher FRAP, TEAC and TPC values than that fermented without residue. On the other hand, the Salvia miltiorrhiza kombucha fermented with residue had similar FRAP and TEAC values but lower TPC values compared to that fermented without residue. The correlation analysis showed that gallic acid, salidroside, and tyrosol were responsible for the antioxidant abilities and total phenolic contents of the Rhodiola rosea kombucha, and salvianolic acid A and salvianolic acid B contributed to the antioxidant abilities of the Salvia miltiorrhiza kombucha. Furthermore, the kombucha fermented with Rhodiola rosea residue had the highest sensory scores among the kombucha beverages studied. These findings suggest that Rhodiola rosea and Salvia miltiorrhiza are suitable for making novel kombucha beverages with strong antioxidant abilities and abundant phenolic contents, which can be used in preventing and managing oxidative stress-related diseases.

Alkali‐induced aggregation behaviour of tea polyphenols and its gel strengthening mechanism to alkali‐induced egg white

SummaryThe effect of black and green tea extracts with different alkali induction degrees on gel properties of alkali‐induced egg white gels (EWGs) was evaluated. Results indicate that, with the increase in alkali induction time, the concentration of soluble polyphenols gradually decreases while their relative polymerisation degree increases, especially for black tea polyphenols. The addition of tea extracts, especially induced by alkaline treatment for 6, 12, and 24 h, can promote the coagulation and browning and inhibit the ‘alkali injury liquefaction’ of alkali‐induced EWGs. Additionally, under alkali‐induced conditions, polyphenols in tea, especially black tea, can enhance the textural properties and thermal stability of alkali‐induced EWGs, this enhancement reaches its peak at 12 h of alkali induction and is consistent with protein secondary structure and interaction forces results. This research provides theoretical support for selection and induction of tea in high‐gel‐strength preserved eggs and other alkali‐induced protein gel food processing.

Let the black tea and green tea take care of your oral health — A short review of the antimicrobial activity of black tea and green tea extracts on

Dental caries is a major global concern and source of great trouble worldwide. It is one of the most common chronic oral diseases in the world that affects both adults and children. The prevalence of DMFT index as a diagnostic criterion in the estimation of dental caries in the age group of 3–18 years was found to be 57%, whereas in patients aged above 18 years, it was much higher that is 77%.Many studies have been carried out all over the world to find the cause behind it, and the main cause, which was well accepted by the people, was the action of pathogenic bacterial microflora such as ( in the oral cavity on the tooth surfaces. These bacteria strongly adhere to the tooth surface and produce lactic acid after fermentation of sucrose and various carbohydrates, which is responsible for the cavitation in the teeth. Many experiments and efforts have been made to remove from the oral cavity, like antibiotics, oral drugs, and more, which are beneficial but have side effects after long-term use, such as vomiting, diarrhea, resistance, teeth staining, etc.That's why search ended at tea which is becoming a popular beverage and a widely consumed drink these days that has anti-streptococcal properties with least of side effect.India's tea usage changed over time from being a colonial export to a regular beverage. With over 29% of the global tea production, India is one of the world's biggest producers and consumers. In India, tea has long been closely linked to the medicinal herbs that have long been used for both therapeutic purposes and general well-being.

Effects of tea infusion on selenium uptake in grapevine

Increased selenium (Se) content in fruits can supply Se in human body, but the effects of teas on the Se uptake in fruit trees are unknown. The effects of infusions of four teas (green, black, dark, and white) on the Se uptake of grapevine were studied to promote the Se uptake in fruit trees in this study. However, only black tea infusion increased the biomass, photosynthetic pigment content, superoxide dismutase (SOD) activity, peroxidase (POD) activity, and soluble protein content of grapevine. Except for white tea infusion, other tea infusions also increased the catalase (CAT) activity of grapevine. Furthermore, the tea infusions increased the activities of adenosine triphosphate sulfurase (ATPS) and adenosine 5’-phosphosulfate reductase (APR), and decreased the activities of serine acetyltransferase (SAT) and selenocysteine methyltransferase (SMT). Only the dark and white tea infusions increased the shoot total Se content by 86.53% and 23.32%, respectively (compared with the control), and also increased the shoot inorganic Se content and shoot organic Se content. Notably, four tea infusions decreased the organic Se proportion and increased the inorganic Se proportion in grapevine. Correlation and grey relational analyses showed that the root total Se content, ATPS activity, and ARP activity were closely associated with the shoot total Se content. The principal component and cluster analyses also showed that the ATPS activity, APR activity, root total Se content, and shoot total Se content were classified into one category. These findings show that black tea infusion can promote grapevine growth, while dark and white tea infusions can promote the Se uptake in grapevine.

A Comparative Study of the Effect Coffee and Tea on Some Parameters in the Rats Blood

Abstract Background: Tea and coffee have been consumed since decade ago and became a significant part of social life and cultural traditions. Objective: The study aims to evaluate the effects of coffee and black tea extract on some blood factors in adult albino rats. Materials and Methods: Eighteen adult male albino rats, classified into three groups of six: group 1 (control) received orally drinking water only, group 2 (tea) received orally extract tea, group 3 (coffee) treated orally with coffee. Coffee and tea extracts were prepared daily at a dose of 30 g/L and provided at all times to the rats for 30 day as drinking water. Iron and ferritin levels, cholesterol concentration of low-density lipoprotein (LDL) and high-density lipoprotein (HDL), superoxide dismutase (SOD), glutathione peroxidase (GPx) activities as well as the levels of tumor necrosis factor-alpha (TNF-α), and interleukin-6 (IL-6) were compared among these groups. Results: This study inferred, there was a significant decrease the amount of iron in the blood as well as the ferritin. Also consumption of coffee or tea lowers LDL cholesterol and HDL cholesterol and enhanced antioxidant activity by SOD and GPx enzymes more than control group. Furthermore, increased these levels in proinflammatory cytokines (IL-6 and TNF-α) in treated rats with tea and coffee extract more than their levels in the control group. Conclusion: The extracts of tea and coffee lowered the iron and ferritin concentration, have remarkable antioxidant activity, and increased the levels in proinflammatory cytokines (IL-6 and TNF-α) in the rat blood.

High-throughput screening, “protein–metabolite” interaction, and hypoglycemic effect investigations of α-amylase inhibitors in teas using an affinity selection-mass spectrometry method

Tea is consumed worldwide and can reduce the risk of diabetes whereas the hypoglycemic compounds in tea remain unclear. Herein, the chemical compositions comparison and inhibition assays indicated that the inhibitory effect of tea against α-amylase was positively related with the enzyme-mediated oxidation degree of tea and black teas containing high contents of theaflavins exhibited the strongest in vitro inhibitory effect. Affinity selection-mass spectrometry-based high-throughput screening revealed that four theaflavins specifically bind to α-amylase. Compared to other compounds, theaflavins showed one order of magnitude higher in vitro inhibitory effects; thus, theaflavins are possibly the dominant α-amylase inhibitors in tea. A series of “α-amylase–theaflavins” interaction studies jointly demonstrated that theaflavins noncompetitively inhibit α-amylase activity by interacting with the amino acid residues of α-amylase and then inducing changes in the secondary structure. Furthermore, theaflavins (10 mg/kg/d) and black tea extracts (100 mg/kg/d) exhibited comparable hypoglycemic effects as acarbose in diabetic mice.

Effect of tea extract (Camellia sinensis) on shelf life and intrinsic quality of tempe

Tempe is Indonesian traditional food made from fermented soybeans. Tempe has a short shelf life due to its high moisture content and the activity of microorganisms. The shelf life of tempe can be increased by using tea extract in tempe processing because tea contains antioxidant and antimicrobial components. This research aims to evaluate the effect of using tea extract in tempe processing on the shelf life, physicochemical characteristics, and sensory profile of tempe. During storage, the shelf-life test used the descriptive observation method on the colour, flavour, taste, and texture. The use of 0.5% black tea extract in the initial soaking of soybeans can increase the shelf life of tempe to 4 and 6 days at room and refrigerator temperature, respectively. The result showed that tempe had significantly (p<0.05) lower ash content (0.81% wb), brightness (65.37), and pH (6.50), while the texture (15.3 Kg force) was significantly higher (p<0.05) than the control (untreated tempe). The results of sensory evaluation using the hedonic rating test showed that fresh tempe with black tea extract treatment had significantly lower (p<0.05) colour, texture, and overall attributes than the control one. The same evaluation on fried tempe showed that the black tea extract treatment significantly increased (p<0.05) the texture attribute compared to the control.