Tea as a Source of Biologically Active Compounds in the Human Diet

Coffee and tea consumption and glioma risk: a meta-analysis of cohort studies

Background

Research on the association between glioma risk and coffee and tea consumption remains inconclusive. This study seeks to present a meta-analysis of the relationship between coffee and tea intake and glioma risk.

Method

Relevant cohort studies that collected coffee and tea exposure prospectively were identified through searches of the PubMed, Embase, and Scopus databases. Eligible studies included those providing adjusted relative risk estimates or hazard ratios (HRs) with 95% confidence intervals (CIs), or data sufficient for such calculations. Study quality was evaluated using the Newcastle-Ottawa Scale, while the GRADE system assessed the quality of evidence. The analysis explored glioma risk concerning the highest versus lowest levels of coffee and tea intake, supplemented by a dose-response evaluation using a one-stage robust error meta-regression model.

Results

A total of nine studies, published between 2004 and 2020, were included. In a model comparing the highest and lowest levels of coffee and tea consumption, 3,896 glioma cases were identified among 2,648,468 participants. Correspondingly, the pooled HRs with 95% CIs were 0.98 (0.87-1.09) for coffee and 0.95 (0.86-1.06) for tea, respectively. Furthermore, no evidence of publication bias was detected for either beverage. The dose-response analysis indicated a near "L"-shaped relationship between tea consumption and glioma risk, with the most notable risk reduction observed in individuals consuming more than 2.5 cups of tea per day. However, additional tea intake beyond this threshold did not confer evident risk reduction. According to Grade scoring system, the quality of meta-evidence was classified as "very low" for coffee and "low" for tea.

Conclusion

This meta-analysis provides evidence suggesting a potential inverse association between tea consumption and glioma risk, while no such association was observed for coffee consumption. Given that the evidence for coffee was classified as "very low" and for tea as "low," cautious interpretation of the findings is warranted, and further research is needed to validate these results.

Effect of the Addition of Yellow Mealworm (Tenebrio molitor) on the Physicochemical, Antioxidative, and Sensory Properties of Oatmeal Cookies

Edible insects are receiving increased attention as a new food source, although research on their implementation in confectionary products remains scarce. The study analyzed the chemical composition, physical parameters, antioxidative, and sensory characteristics of oatmeal cookies reformulated with yellow mealworm larvae (Tenebrio molitor L.; TM) at 0% (TM0), 10% (TM10), and 30% (TM30). The inclusion of TM in the cookie recipe increased the protein and fat content, improved the ratio of n-6/n-3 acids, and raised oleic acid levels while reducing palmitic acid. Oatmeal cookies were rich in K and P, and including TM significantly increased the content of most minerals, except for Mn and Na. The cookies held significant antioxidant capacity that increased as the concentration of TM increased due to hydrophilic antioxidants. Although lightness decreased with the increase in mealworm substitution, the yellowness, chroma, and hue angle remained similar for TM0 and TM10. The TM30 cookies were significantly darker and softer, which was further confirmed by panelists. The cookie formulation effectively masked the taste and smell of TM since there were no evident differences between the control and TM10 cookies. Cookies with TM30 received high enough ratings to be considered attractive if differentiated sensory characteristics are desired.

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.

Influence of Primary Light Exposure on the Morphophysiological Characteristics and Phenolic Compounds Accumulation of a Tea Callus Culture (Camellia sinensis L.)

Tea plant calli (Camellia sinensis L.) are characterized by the accumulation of various phenolic compounds (PC)-substances with high antioxidant activity. However, there is still no clarity on the response of tea cells to light exposure of varying intensity. The purpose of the research was to study tea callus cultures grown under the influence of primary exposure to different light intensities (50, 75, and 100 µmol·m-2·s-1). The cultures' growth, morphology, content of malondialdehyde and photosynthetic pigments (chlorophyll a and b), accumulation of various PC, including phenylpropanoids and flavanols, and the composition of catechins were analyzed. Primary exposure to different light intensities led to the formation of chloroplasts in tea calli, which was more pronounced at 100 µmol·m-2·s-1. Significant similarity in the growth dynamics of cultures, accumulation of pigments, and content of malondialdehyde and various phenolics in tea calli grown at light intensities of 50 and 75 µmol·m-2·s-1 has been established, which is not typical for calli grown at 100 µmol·m-2·s-1. According to data collected using high-performance liquid chromatography, (+)-catechin, (-)-epicatechin, epigallocatechin, gallocatechin gallate, epicatechin gallate, and epigallocatechin gallate were the main components of the tea callus culture's phenolic complex. Its content changed under the influence of primary exposure to light, reaching the greatest accumulation in the final stages of growth, and depended on the light intensity. The data obtained indicate changes in the morphophysiological and biochemical characteristics of tea callus cultures, including the accumulation of PC and their individual representatives under primary exposure to light exposure of varying intensity, which is most pronounced at its highest values (100 µmol·m-2·s-1).

Seasonal variations in the phenolic profile, antioxidant activity, and mineral content of south Indian black tea (Camellia sinensis (L.) O. Kuntze)

In the Anamallais region of south India, crop shoots from the UPASI-3, UPASI-9, UPASI-17, Assam seedlings, and TRI-2043 cultivars were examined for seasonal variations in total phenolics, antioxidant activity, and minerals during four harvest seasons: summer (January to March), premonsoon (April and May), monsoon (June to September), and winter (October to December) of two consecutive years. The total phenolics of all cultivars were lower in monsoon period and grew over rest of the seasons and it was greater during summer. Crop shoot antioxidant activity as measured by the DPPH radical scavenging experiment exhibited a similar pattern to total phenolics. Summer was the season with the highest antioxidant activity across all cultivars, followed by premonsoon, winter, and monsoon. On the other hand, the employed cultivars differed noticeably in terms of seasonal change of minerals. These results appear to indicate that the harvest period is hypercritical in deciding the antioxidant potency of tea crop shoots.

The Bioactive Substances in Spent Black Tea and Arabic Coffee Could Improve the Nutritional Value and Extend the Shelf Life of Sponge Cake after Fortification

The study aimed to evaluate the potential use of spent coffee powder (SCP) and spent tea powder (STP) as bioactive supplements for sponge cake. To achieve this aim, we initially compared the chemical properties of spent tea and coffee powders with those of their raw forms. Subsequently, three supplemented cake blends were prepared (1, 2, and 3% of SCP and STP) to test the effect of their addition on the chemophysical characteristics, sensory attributes, and shelf life of the final products. Our results indicated that spent tea and coffee are prospective materials for polyphenols. Spent tea powder could retain up to 72% (theaflavin trigallate), while spent coffee powder could retain up to 63.9% (1-caffeoylquinic acid) of the identified compounds compared to the raw materials. Furthermore, spent tea and coffee powders contained high levels of dietary fiber (18.95 and 31.65 g/100 g dry weight) and the elements potassium (254.6 and 1218.2 mg/100 g of DW), phosphorus (189.8 and 161.3 mg/100 g of DW), calcium (904.1 and 237.8 mg/100 g of DW), and magnesium (158.8 and 199.6 mg/100 g of DW). In addition, the fortified samples with SCP and STP significantly enhanced the nutritional values while retaining good sensory qualities compared to those of the control sample. Moreover, cakes fortified with the highest concentrations of SCP and STP (3%) showed a significant decrease in malondialdehyde content (MDA; 17.7 and 18.0 μg/g) and microbiological counts (2.4 and 2.5 log cfu/g) compared to the control cake after 14 days of storage. These findings suggest that incorporating SCP and STP into cakes not only enhances their nutritional value but also extends their shelf life. By utilizing these waste products, we can contribute to a more sustainable and ecofriendly food industry.

Catechins and Selenium Species-How They React with Each Other

The combination of selenium and tea infusion, both with antioxidant properties, has potentially complementary mechanisms of action. Se-enriched tea has been considered as a possible Se supplement and a functional beverage to reduce the health risk of Se deficiency. This work investigated the interactions between plant catechins present in tea infusions and selenium species based on changes in the concentration of both reagents, their stability in aqueous solutions, and the possibilities of selenonanoparticles (SeNPs) formation. Selenium species exhibited instability both alone in their standard solutions and in the presence of studied catechins; selenocystine appeared as the most unstable. The recorded UV-Vis absorption spectra indicated the formation of SeNPs in the binary mixtures of catechins and selenite. SeNPs have also formed with diameters smaller than 100 nm when selenite and selenomethionine were added to tea infusions. This is an advantage from the point of view of potential medical applications.

Advanced mass spectrometry profiling of phenolic and minerals compounds in herbal beverages

The global pandemic of COVID-19 has led to an increased interest in herbal infusions as natural remedies since 2020. This has also heightened the need for controlling the composition of these dietary supplements to ensure consumer health and prevent food fraud. In the present work, various mass spectrometry techniques were used to analyze the organic and inorganic composition of 23 herbal infusion samples. UHPLC-ESI-QTOF-MS was used to determine target, suspect, and nontarget polyphenolic compounds. Thus, 8 phenolic compounds were identified in the target analysis and additionally, 80 extra-compounds were identified through suspect and nontargeted screening. ICP-MS was used to monitor the metals released during tea leaf infusion, providing a complete mineral composition of each sample. Principal Component Analysis (PCA) and Discriminant Analysis (DA) were utilized to identify relevant compounds for differentiating and grouping the samples, thus serving as specific markers to detect potential food fraud.

Utilising Spent Tea Leaves Powder as Functional Ingredient to Enhance the Quality of Non-Gluten Shortbread Cookies

The increasing prevalence of gluten-related disorders has led to higher consumer demand for convenient, gluten-free bakery products with health-promoting properties. In this study, non-gluten shortbread cookies were incorporated with various kinds of spent (green, oolong, and black) tea leaves powder (STLP) at 8% w/w. Cookies with STLP had significantly higher (p < 0.05) moisture (2.18-2.35%), crude fibre (14.5-14.9%), total dietary fibre (22.38-22.59%), insoluble dietary fibre (15.32-15.83%), soluble dietary fibre (7.06-7.66%), and ash (1.9-2.0%) contents, but were significantly lower (p < 0.05) in carbohydrate (53.2-53.9%) and energy value (426.4-428.2 kcal) compared to control cookies (1.62%; 1.43%; 6.82%; 4.15%; 2.67%; 7.70%; 62.2%; and 457.8 kcal, respectively). The addition of STLP significantly enhanced (p < 0.05) the antioxidant properties of the cookies. Non-gluten shortbread cookies with spent green tea leaves powder (GTC) received the highest (p < 0.05) score for all sensory attributes, including overall acceptability. In addition, the shelf-life quality of the formulated cookie samples in terms of the moisture content, water activity, colour, texture, microbiology, and sensory properties was maintained (p > 0.05) for at least 22 days at 25 °C. STLP, which would have been previously thrown away, could be utilized as a potential functional ingredient to produce non-gluten shortbread cookies with enhanced nutritional, physicochemical, microbiological, sensory, and antioxidative properties.

Harvest Stage and Brewing Conditions Impact Mineral Content, Phenolic Compounds, and Antioxidant Capacity of Lemon Balm (Melissa officinalis L.) Herbal Tea

Lemon balm (Melissa officinalis L.) is commonly consumed as an herbal tea for its antioxidant health benefits. Young seedlings known as microgreens are popular for their distinct flavors and can contain higher mineral content on a dry weight basis compared to their adult counterparts. However, the use of microgreens for herbal teas has not been previously investigated. In this study, lemon balm was grown to adult and microgreen harvest stages and prepared as herbal teas by brewing with boiled (100 °C) water for 5 minutes and room temperature water (22 °C) for 2 hours. The effects of harvest time and brewing method on the mineral content, phenolic compounds, and antioxidant capacity of lemon balm herbal teas were assessed. Results showed that adult lemon balm tea contained higher total phenolics, total flavonoids, rosmarinic acid, and antioxidant capacity than microgreen teas, with hot preparations containing the highest amounts (p ≤ 0.05). In contrast, microgreen lemon balm teas contained higher amounts of minerals (p ≤ 0.05), including calcium, potassium, magnesium, sodium, phosphorus, copper, and zinc. In general, brewing conditions did not impact the content of most minerals. Overall, the results support the potential of using dried microgreens as herbal teas. Microgreen lemon balm teas prepared hot and cold offer antioxidant compounds and are richer sources of minerals than adult teas. The ease of growth for microgreens offers consumers the opportunity for home preparation of a novel herbal tea beverage.

Health-Promoting Ingredients in Goat's Milk and Fermented Goat's Milk Drinks

The present study aimed to determine the content of health-promoting compounds, and fatty acids, with particular emphasis on the content of cis9trans11 C18:2 (CLA) acid, selected minerals, folates in organic and commercial goat's milk and fermented goat's milk drinks. The analyzed milk and yoghurts had various contents of particular groups of fatty acids, CLA, minerals, and folates. Raw organic goat's milk had a significantly (p < 0.05) higher content of CLA (3.26 mg/g fat) compared to commercial milk (2.88 mg/g fat and 2.54 mg/g fat). Among the analyzed fermented goat's milk drinks, the highest CLA content (4.39 mg/g fat) was determined in commercial natural yoghurts, while the lowest one was in organic natural yoghurts (3.28 mg/g fat). The highest levels of calcium (1322.9-2324.4 µg/g), phosphorus (8148.1-11,309.9 µg/g), and copper (0.072-0.104 µg/g) were found in all commercial products and those of manganese (0.067-0.209 µg/g) in organic products. The contents of the other assayed elements (magnesium, sodium, potassium, iron, and zinc) did not depend on the production method, but only on the product type, i.e., the degree of goat's milk processing. The highest folate content in the analyzed milks was found in the organic sample (3.16 µg/100 g). Organic Greek yoghurts had a several times higher content of folates, reaching 9.18 µg/100 g, compared to the other analyzed fermented products.

Marine enzymes: Classification and application in various industries

Oceans are regarded as a plentiful and sustainable source of biological compounds. Enzymes are a group of marine biomaterials that have recently drawn more attention because they are produced in harsh environmental conditions such as high salinity, extensive pH, a wide temperature range, and high pressure. Hence, marine-derived enzymes are capable of exhibiting remarkable properties due to their unique composition. In this review, we overviewed and discussed characteristics of marine enzymes as well as the sources of marine enzymes, ranging from primitive organisms to vertebrates, and presented the importance, advantages, and challenges of using marine enzymes with a summary of their applications in a variety of industries. Current biotechnological advancements need the study of novel marine enzymes that could be applied in a variety of ways. Resources of marine enzyme can benefit greatly for biotechnological applications duo to their biocompatible, ecofriendly and high effectiveness. It is beneficial to use the unique characteristics offered by marine enzymes to either develop new processes and products or improve existing ones. As a result, marine-derived enzymes have promising potential and are an excellent candidate for a variety of biotechnology applications and a future rise in the use of marine enzymes is to be anticipated.

Does the Type Matter? Verification of Different Tea Types' Potential in the Synthesis of SeNPs

Selenium nanoparticles (SeNPs) are gaining popularity due to their potential biomedical applications. This work describes their green synthesis using various types of tea. Black, green, red and white tea infusions were tested for the content of polyphenolic compounds and antioxidant properties and then used in the synthesis of SeNPs. In each of the syntheses, nanoparticles with dimensions ranging from 3.9 to 12.5 nm, differing in shape and properties, were obtained. All of them were characterized by a very high ability to neutralize hydroxyl radicals, which was about three-times higher than for the tea infusions from which they were obtained. The main inconvenience in obtaining SeNPs was the difficulties with their purification, which should be a further stage in the described research.

Mini-Review on the Enzymatic Lipophilization of Phenolics Present in Plant Extracts with the Special Emphasis on Anthocyanins

Different plant extracts have the potential to be important sources of phenolic compounds. Their antibacterial, antifungal and antioxidant properties are of interest to researchers due to various possibilities for use in the pharmacy, cosmetic and food industries. Unfortunately, the direct application of phenolics in food is limited because of their hydrophilic nature and low solubility. The review is devoted to the recent advances in the methods of lipophilization of phenolic extracts along with the use of enzymes. The concept of extract modification instead of single compound modification is based on the expected synergistic effect of many phenolic compounds. The main focus is on the phenolic compounds found in fruits, flowers and leaves of different common and underutilized as well as medicinal, folk-medicinal or endemic plants. The compiled papers point to the great interest in the modification of anthocyanins, highly active but often unstable phenolics. Some examples of other flavonoids are also outlined. The possible applications of the lipophilized plant extracts are presented for improving the stability of edible oils, decreasing the content of acrylamide, exhibiting higher color stability in thermal processing and increasing the nutritional value.

Tea Infusions as a Source of Phenolic Compounds in the Human Diet

Phenolic compounds are components with proven beneficial effects on the human body, primarily due to their antioxidant activity. In view of the high consumption of tea and the numerous factors that affect the nutritional value of its infusions, the aim of this study was to identify the effects of tea type and duration of leaf extraction with water on the levels of phenolic compounds and other components that determine biological activity (oxalates, Ca, Na, Cu, and Mn). Based on assays, infusions of red tea prepared for 20 min were found to be the best source of phenolics (202.9 mg/100 mL), whereas the lowest level of these compounds was determined in infusions of black tea extracted from leaves for 30 min (46.9 mg/100 mL). The highest degree of increase in polyphenol content (by approx. 50%) was noted in red and green tea infused for between 10 and 20 min, whereas for black tea, polyphenol levels decreased with time. The biological activity of tea infusions appears to be determined to the greatest extent by the interactions between phenolic compounds and oxalates (r = 0.6209), calcium (r = 0.8516), and sodium (0.8045). A daily intake of three to four mugs (1 L) of tea infusions provides the human body the entire amount of phenolics recommended for health reasons (as regards red tea, this is possible at 1/3 of the volume) and covers the daily requirement for manganese, as well as (partially) copper.

Concentrations, leachability, and health risks of mercury in green tea from major production areas in China

Green tea has many health benefits and is the most consumed type in China. However, the heavy metals and contaminants in tea can also pose a great risk to human health. In this study, mercury (Hg) concentration in green tea collected from 11 provinces in China was examined. The leaching characteristics of Hg during brewing and the associated exposure to drinkers were also evaluated. Results indicated a low potential of Hg accumulation in green tea. The Hg content of green tea from Wanshan District, Guizhou Province-which has the largest Hg mine in China and is severely contaminated by Hg-could be limited by controlling the harvest time of tea leaves. The average Hg content of green tea from 43 tea production sites in China was only 6.3 ± 6.4 µg/kg dry weight. The brewing experiments of green tea showed that the leaching ratio of Hg was 22.61 ± 7.58% for 40 min of a single brew, and increased to 32.83 ± 12.37% after four rounds (3 min/ round) of brewing. The leaching of Hg from tea leaves was significantly affected by leaching time, temperature, and solid-liquid ratio but not by water hardness. The risk of Hg exposure from green tea intake was found to be very low, with an average hazard quotient (HQ) value of only 1.82 ± 1.85% for a single brew in 40 min and 2.64 ± 2.68% after four rounds of brewing. However, in some highly contaminated areas, with HQ values as high as 43.12 ± 2.41%, green tea intake may still pose a high risk of Hg exposure, and this risk should not be ignored.

Processing, chemical signature and food industry applications of Camellia sinensis teas: An overview

The plant Camellia sinensis is the source of different teas (white, green, yellow, oolong, black, and pu-ehr) consumed worldwide, which are classified by the oxidation degree of their bioactive compounds. The sensory (taste, aroma, and body of the drink) and functional properties of teas are affected by the amount of methylxanthines (caffeine and theobromine), amino acids (l-theanine) and reducing sugars in their composition. Additionally, flavan-3-ols, mainly characterized by epicatechins, catechins, and their derivatives, represent on average, 60% of the bioactive compounds in teas. These secondary metabolites from teas are widely recognized for their antioxidant, anti-cancer, and anti-inflammatory properties. Thus, Camellia sinensis extracts and their isolated compounds have been increasingly used by the food industry. However, bioactive compounds are very susceptible to the oxidation caused by processing and degradation under physiological conditions of gastrointestinal digestion. In this context, new approaches/technologies have been developed for the preservation of these compounds. This review presents the main stages involved in production of Camellia sinensis teas following a description of their main bioactive compounds, biological properties, stability and bioaccessibility. Besides, and updated view of Camellia sinensis teas in the field of food science and technology was provided by focusing on novel findings and innovations published in scientific literature over the last five years.

Campylobacter Biofilms: Potential of Natural Compounds to Disrupt Campylobacter jejuni Transmission

Microbial biofilms occur naturally in many environmental niches and can be a significant reservoir of infectious microbes in zoonotically transmitted diseases such as that caused by Campylobacter jejuni, the leading cause of acute human bacterial gastroenteritis world-wide. The greatest challenge in reducing the disease caused by this organism is reducing transmission of C. jejuni to humans from poultry via the food chain. Biofilms enhance the stress tolerance and antimicrobial resistance of the microorganisms they harbor and are considered to play a crucial role for Campylobacter spp. survival and transmission to humans. Unconventional approaches to control biofilms and to improve the efficacy of currently used antibiotics are urgently needed. This review summarizes the use plant- and microorganism-derived antimicrobial and antibiofilm compounds such as essential oils, antimicrobial peptides (AMPs), polyphenolic extracts, algae extracts, probiotic-derived factors, d-amino acids (DAs) and glycolipid biosurfactants with potential to control biofilms formed by Campylobacter, and the suggested mechanisms of their action. Further investigation and use of such natural compounds could improve preventative and remedial strategies aimed to limit the transmission of campylobacters and other human pathogens via the food chain.