Compositional, nutritional, and functional characteristics of instant teas produced from low- and high-quality black teas

Chemical, sensory and biological variations of black tea under different drying temperatures

As the final processing step, drying temperature between 90 and 140 ℃ is usually applied to terminate enzymatic activities and improve sensory characteristics of black tea. Liquid chromatography tandem mass spectrometry (LC-MS) based non-targeted and targeted metabolomics analyses combined in vitro biological assays were adopted to investigate the chemical and biological variations after drying. Fifty-nine differentially expressed metabolites including several hydroxycinnamic acid derivatives and pyroglutamic acid-glucose Amadori rearrangement products (ARPs) were identified, the latter of which was correspondingly accumulated with increasing temperature. The levels of theaflavins (TFs), thearubigins (TRs), monosaccharides and free amino acids gradually decreased with increasing temperature. Furthermore, the bioassays of black tea showed that drying under 110 ℃ provided the highest antioxidant capacities, but the inhibitory effects on α-glucosidase and α-amylase were decreasing along with increasing drying temperature. These results are valuable for optimizing drying process to obtain superior sensory properties and preserve bioactivities of black tea.

The effect of intercropping leguminous green manure on theanine accumulation in the tea plant: A metagenomic analysis

Intercropping is a widely recognised technique that contributes to agricultural sustainability. While intercropping leguminous green manure offers advantages for soil health and tea plants growth, the impact on the accumulation of theanine and soil nitrogen cycle are largely unknown. The levels of theanine, epigallocatechin gallate and soluble sugar in tea leaves increased by 52.87% and 40.98%, 22.80% and 6.17%, 22.22% and 29.04% in intercropping with soybean-Chinese milk vetch rotation and soybean alone, respectively. Additionally, intercropping significantly increased soil amino acidnitrogen content, enhanced extracellular enzyme activities, particularly β-glucosidase and N-acetyl-glucosaminidase, as well as soil multifunctionality. Metagenomics analysis revealed that intercropping positively influenced the relative abundances of several potentially beneficial microorganisms, including Burkholderia, Mycolicibacterium and Paraburkholderia. Intercropping resulted in lower expression levels of nitrification genes, reducing soil mineral nitrogen loss and N2 O emissions. The expression of nrfA/H significantly increased in intercropping with soybean-Chinese milk vetch rotation. Structural equation model analysis demonstrated that the accumulation of theanine in tea leaves was directly influenced by the number of intercropping leguminous green manure species, soil ammonium nitrogen and amino acid nitrogen. In summary, the intercropping strategy, particularly intercropping with soybean-Chinese milk vetch rotation, could be a novel way for theanine accumulation.

Exploring Plants with Flowers: From Therapeutic Nutritional Benefits to Innovative Sustainable Uses

Flowers have played a significant role in society, focusing on their aesthetic value rather than their food potential. This study's goal was to look into flowering plants for everything from health benefits to other possible applications. This review presents detailed information on 119 species of flowers with agri-food and health relevance. Data were collected on their family, species, common name, commonly used plant part, bioremediation applications, main chemical compounds, medicinal and gastronomic uses, and concentration of bioactive compounds such as carotenoids and phenolic compounds. In this respect, 87% of the floral species studied contain some toxic compounds, sometimes making them inedible, but specific molecules from these species have been used in medicine. Seventy-six percent can be consumed in low doses by infusion. In addition, 97% of the species studied are reported to have medicinal uses (32% immune system), and 63% could be used in the bioremediation of contaminated environments. Significantly, more than 50% of the species were only analysed for total concentrations of carotenoids and phenolic compounds, indicating a significant gap in identifying specific molecules of these bioactive compounds. These potential sources of bioactive compounds could transform the health and nutraceutical industries, offering innovative approaches to combat oxidative stress and promote optimal well-being.

Evaluation of Physicochemical Properties of a Hydrocolloid-Based Functional Food Fortified with Caulerpa lentillifera: A D-Optimal Design Approach

This study introduced a D-optimal design mixture to assess the physicochemical properties of a hydrocolloid-based functional food fortified with C. lentillifera. The combination incorporated vital jelly constituents, including extract (10-15%), sweeteners (20-29%), gelling agents (k-carrageenan and locust bean gum (LBG)), and preservatives (0-0.05%). The dependent variables were pH, Total Soluble Solid (TSS) value, and moisture content (MS). By employing the D-optimal design approach, a quadratic polynomial model was developed, demonstrating strong correlations with the experimental data with coefficient determinations (R²) of 0.9941, 0.9907, and 0.9989 for pH, TSS, and MS, respectively. Based on the D-optimal design, the study identified the optimum combination of significant factors with a desirability of 0.917, comprising 14.35% extract, 23.00% sucrose, 21.70% fructose, 26.00% k-carrageenan, 13.00% LBG, 1.95% CaCl₂, and 0% methylparaben. The percentage of residual standard error (RSE) was less than 5%, indicating the reliability of the developed model. Furthermore, color analysis revealed significant differences among the jellies (p < 0.05). HPLC analysis demonstrated that the total sugar content in the fortified jellies was 28% lower compared to commercial jelly. Meanwhile, the bitterness level according to e-tongue showed a reduction of up to 90.5% when compared to the extract. These findings provide a valuable benchmark for the development of functional food products, ensuring their quality, safety, and extended shelf-life.

Phenolic Content, Main Flavonoids, and Antioxidant Capacity of Instant Sweet Tea (Lithocarpus litseifolius [Hance] Chun) Prepared with Different Raw Materials and Drying Methods

This study aims to investigate the effects of raw materials and drying methods on the phytochemical and antioxidant capacities of instant sweet tea powder. Four raw materials of sweet tea leave powders (STUT) were extracted and dried with two methods (freeze-drying and spray-drying). The antioxidant capacity, total phenolic content (TPC), total flavonoid content (TFC), and phlorizin and trilobatin contents of obtained instant sweet tea powders were compared. In addition, the single-factor experiments coupled with response surface methodology were used to study the influences of solvent-to-sample ratio, extraction temperature, extraction time, and their interactions on instant sweet tea yield. Results showed that the optimal conditions for extraction were the solvent-to-sample ratio of 19:1 mL/g, extraction temperature of 88 °C, and extraction time of 30 min. The TPC, TFC, antioxidant capacities, and phloridzin and trilobatin contents of instant sweet teas were higher than those of STUT, and the TPC and TFC of freeze-dried instant sweet teas were higher than those of spray-dried instant sweet teas. Significant correlations were found among TPC, TFC, and antioxidant capacities (p < 0.01). The freeze-dried instant sweet tea produced by young leaves (prepared by oven-drying) showed the highest TPC, TFC, and antioxidant capacities, compared with other raw materials and drying methods.

Occurrence and Risk of Metal(loid)s in Thelesperma megapotamicum Tea Plant

This study reports on the harvesting, ingestion, and contamination of American Indian tea Thelesperma megapotamicum grown on the Navajo Reservation in New Mexico. Uranium (U) and co-metal(loid)s (As, Cd, Cs, Mo, Pb, Se, Th, and V) have contaminated local soil and plants. Tea plants were gathered for analysis near U mining impacted areas. The study collected samples of wild tea plants (n = 14), roots (n = 14), and soil (n = 12) that were analyzed with inductively coupled plasma mass spectrometry. Tea harvesting activities, behavior, and ingestion information were collected via questionnaires. Harvesting took place in community fields and near roadways. Results indicate edible foliage concentration levels for Cd exceeded the World Health Organization (WHO) raw medicinal plant permissible level guidelines. Tea samples collected near high traffic areas had significantly greater Cd and Mo concentrations than those collected near low traffic areas (p < 0.001). Tea sample metal(loid) concentration levels ranged from 0.019-7.916 mg/kg. When compared to established food guidelines including the WHO provisional tolerable weekly intake (PTWI), reference dietary intake, recommended dietary allowance, and the tolerable upper limit (UL), Cd exceeded the WHO guidelines but none exceeded the PTWI nor the UL. These findings warrant improved standardization and establishment of universal guidelines for metal(loid) intake in food.

Bulk, Foam, and Interfacial Properties of Tannic Acid/Sodium Caseinate Nanocomplexes

For this work, the aim was to investigate the adsorption of the tannic acid (TA)/sodium caseinate (SC) nanocomplexes at the air/water interface and then to research its relationship with foam properties. First, nanocomplexes were prepared in a different mass ratio of TA and SC. The bulk behavior of nanocomplexes was evaluated by dynamic light scattering (DLS), signal-intensifying fluorescence probe (ANS), etc. As the concentration of TA increased, the z-average siameter ( D _z) of TA/SC nanocomplexes decreased gradually and the negative charge increased. Meanwhile, the surface hydrophobicity ( S_o) of the SC also decreased after the addition of TA. The interfacial properties were determined by dynamic surface tension and dilational rheology. The presence of polyphenols decreased the surface pressure (π) that resulted in poor foamability. However, the elastic ( E_d) component of the dilational modulus of films also increased as polyphenols concentration increased, which gave rise to admirable foam stability. The contribution of polyphenols to stabilize foam columns may be caused by interfacial interaction between proteins and polyphenols.

Evaluation and application of prebiotic and probiotic ingredients for development of ready to drink tea beverage

Ready-to-drink (RTD) ice tea is a ready prepared tea, produced from green and black tea originating from same plant Camellia sinensis. The objective of this study was to determine the effect of prebiotics [galacto-oligosaccharide (GOS), fructo-oligosaccharide (FOS), and inulin] or synbiotic ingredients (GOS, FOS, inulin, and Lactobacillus acidophilus) on the sensory properties and consumer acceptability of RTD. The quality of green tea extract (GTE) and black tea extract (BTE) was improved with pretreatment of cellulase and pectinase enzymes. The combined enzymatic extraction amplified total extractives up to 76% in GTE and 72% in BTE. Total polyphenol was found to be enhanced to 24% in GTE and 19% in BTE. GTE was further selected for development of RTD in two different formats; synbiotic RTD and prebiotic RTD premix and analyzed for sensory attributes (colour, aroma, taste, and acceptability). Synbiotic RTD was also evaluated for stability over a period of 28 days at 4 °C. Synbiotic RTD developed an unpleasant flavor and aroma during the shelf life. Premix format of RTD developed using spray drying was reconstituted and found to be functionally and sensorially acceptable.

Micronutrients (B, Co, Cu, Fe, Mn, Mo, and Zn) content in made tea (Camellia sinensis L.) and tea infusion with health prospect: A critical review

Tea (Camellia sinensis L.) is a perennial acidophilic crop, and known to be a nonalcoholic stimulating beverage that is most widely consumed after water. The aim of this review paper is to provide a detailed documentation of selected micronutrient contents, viz. boron (B), cobalt (Co), copper (Cu), iron (Fe), manganese (Mn), molybdenum (Mo), and zinc (Zn) in made tea and tea infusion. Available data from the literature were used to calculate human health aspect associated with the consumption of tea infusion. A wide range of micronutrients reported in both made tea and tea infusion could be the major sources of micronutrients for human. The content of B, Co, Cu, Fe, Mn, Mo, and Zn in made tea are ranged from 3.04 to 58.44 μg g^-1, below detectable limit (BDL) to 122.4 μg g^-1, BDL to 602 μg g^-1, 0.275 to 13,040 μg g^-1, 0.004 to 15,866 μg g^-1, 0.04 to 570.80 μg g^-1 and 0.01 to 1120 μg g^-1, respectively. Only 3.2 μg L^-1 to 7.25 mg L^-1, 0.01 μg L^-1 to 7 mg L^-1, 3.80 μg L^-1 to 6.13 mg L^-1, 135.59 μg L^-1 -11.05 mg L^-1, 0.05 μg L^-1 to 1980.34 mg L^-1, 0.012 to 3.78 μg L^-1, and 1.12 μg L^-1 to 2.32 μg L^-1 of B, Co, Cu, Fe, Mn, Mo, and Zn, respectively, are found in tea infusion which are lower than the prescribed limit of micronutrients in drinking water by World Health Organization. Furthermore, micronutrient contents in tea infusion depend on infusion procedure as well as on the instrument used for analysis. The proportion of micronutrients found in different tea types are 1.0-88.9% for B, 10-60% for Co, 2.0-97.8% for Cu, 67.8-89.9% for Fe, 71.0-87.4% for Mn, 13.3-34% for Mo, and 34.9-83% for Zn. From the results, it can also be concluded that consumption of three cups of tea infusion per day does not have any adverse effect on human health with respect to the referred micronutrients rather got beneficial effects to human.

"Turn-off" fluorescent sensor based on double quantum dots coupled with chemometrics for highly sensitive and specific recognition of 53 famous green teas

Fluorescent "turn-off" sensors based on double quantum dots (QDs) has attracted increasing attention in the detection of many materials due to their properties such as more useful information, higher fluorescence efficiency and stability compared with the fluorescent "turn-off" sensors based on single QDs. In this work, highly sensitive and specific method for recognition of 53 different famous green teas was developed based on the fluorescent "turn-off" model with water-soluble ZnCdSe-CdTe double QDs. The fluorescence of the two QDs can be quenched by different teas with varying degrees, which results in the differences in positions and intensities of two peaks. By the combination of classic partial least square discriminant analysis (PLSDA), all the green teas can be discriminated with high sensitivity, specificity and a satisfactory recognition rate of 100% for training set and 100% for prediction set, respectively. The fluorescent "turn-off" sensors based on the single QDs (either ZnCdSe QDs or CdTe QDs) coupled with PLSDA were also employed to recognize the 53 famous green teas with unsatisfactory results. Therefore, the fluorescent "turn-off" sensors based on the double QDs is more appropriate for the large-class-number classification (LCNC) of green teas. Herein, we have demonstrated, for the first time, that so many kinds of famous green teas can be discriminated by the "turn-off" model of double QDs combined with chemometrics, which has largely extended the capability of traditional fluorescence and chemometrics, as well as exhibits great potential to perform LCNC in other practical applications.

Antimutagenic and anticlastogenic effects of Turkish Black Tea on TA98 and TA100 strains of Salmonella typhimurium (in vitro) and mice (in vivo)

CONTEXT

Black tea has been reported to have significant antimutagenic and anticarcinogenic properties associated with its polyphenols theaflavins (TF) and thearubigins (TR). Similarly, Turkish black tea (TBT) also contains a considerable amount of TF and TR.

OBJECTIVE

This study investigated the mutagenic, antimutagenic and anticlastogenic properties of TBT.

MATERIALS AND METHODS

The mutagenic and antimutagenic effects of TBT (10 to 40000 μg/plate) were investigated in vitro on Salmonella strains TA98 and TA100 with and without S9 fraction. Anticlastogenic effect was studied at concentrations of 300-1200 mg/kg TBT extract by chromosomal aberrations (CA) assay from bone marrow of mice.

RESULTS

The results of this study did not reveal any mutagenic properties of TBT. On the contrary, TBT extract exhibited antimutagenic activity at >1000 μg/plate concentrations in TA98 strain with and without S9 activation (40% inhibition with S9 and 27% without S9). In TA100 strain, the antimutagenic activity was observed at >20,000 μg/plate TBT extracts without S9 activation (28% inhibition) and at >1000 μg/plate with S9 activation (59% inhibition). A significant decrease in the percentage of aberrant cells (12.33% ± 1.27) was observed in dimethylbenz(a)anthracene (DMBA) plus highest concentration (1200 mg/kg) of TBT extract-treated group when compared to only DMBA-treated group (17.00% ± 2.28).

DISCUSSION AND CONCLUSION

Results indicated that TBT can be considered as genotoxically safe, because it did not exert any mutagenic and clastogenic effects. As a result, TBT exhibited antimutagenic effects more apparently after metabolic activation in bacterial test system and had an anticlastogenic effect in mice.

Phytochemical Content, Health Benefits, and Toxicology of Common Edible Flowers: A Review (2000-2015)

Edible flowers contain numerous phytochemicals which contribute to their health benefits, and consumption of edible flowers has increased significantly in recent years. While many researchers have been conducted, no literature review of the health benefits of common edible flowers and their phytochemicals has been compiled. This review aimed to present the findings of research conducted from 2000 to 2015 on the species, traditional application, phytochemicals, health benefits, and the toxicology of common edible flowers. It was found in 15 species of common edible flowers that four flavonols, three flavones, four flavanols, three anthocyanins, three phenolic acids and their derivatives were common phytochemicals and they contributed to the health benefits such as anti-oxidant, anti-inflammatory, anti-cancer, anti-obesity, and neuroprotective effect. Toxicology studies have been conducted to evaluate the safety of common edible flowers and provide information on their dosages and usages.

Polyphenol compounds and PKC signaling

BACKGROUND

Naturally occurring polyphenols found in food sources provide huge health benefits. Several polyphenolic compounds are implicated in the prevention of disease states, such as cancer. One of the mechanisms by which polyphenols exert their biological actions is by interfering in the protein kinase C (PKC) signaling pathways. PKC belongs to a superfamily of serine-threonine kinase and are primarily involved in phosphorylation of target proteins controlling activation and inhibition of many cellular processes directly or indirectly.

SCOPE OF REVIEW

Despite the availability of substantial literature data on polyphenols' regulation of PKC, no comprehensive review article is currently available on this subject. This article reviews PKC-polyphenol interactions and its relevance to various disease states. In particular, salient features of polyphenols, PKC, interactions of naturally occurring polyphenols with PKC, and future perspective of research on this subject are discussed.

MAJOR CONCLUSIONS

Some polyphenols exert their antioxidant properties by regulating the transcription of the antioxidant enzyme genes through PKC signaling. Regulation of PKC by polyphenols is isoform dependent. The activation or inhibition of PKC by polyphenols has been found to be dependent on the presence of membrane, Ca(2+) ion, cofactors, cell and tissue types etc. Two polyphenols, curcumin and resveratrol are in clinical trials for the treatment of colon cancer.

GENERAL SIGNIFICANCE

The fact that 74% of the cancer drugs are derived from natural sources, naturally occurring polyphenols or its simple analogs with improved bioavailability may have the potential to be cancer drugs in the future.

Volatile compounds and sensory characteristics of various instant teas produced from black tea

Various instant teas produced differently from black tea [freeze-dried instant tea (FDIT), spray-dried instant tea (SDIT), and decaffeinated instant tea (DCIT)], were compared for their differences in volatile compounds as well as descriptive sensory analysis (DSA). A total of 63 volatile compounds in all tea samples (eight aldehydes, ten alcohols, nine ketones, five esters, eight acids, ten terpenes/terpenoids, ten furans/furanones, two pyrroles, and one miscellaneous compound) were tentatively identified. Black tea, FDIT, SDIT, and DCIT contained 60, 55, 47, and 40 volatile compounds, respectively. Ten flavour attributes such as after taste, astringency, bitter, caramel-like, floral/sweet, green/grassy, hay-like, malty, roasty, and seaweed were identified. Intensities for a number of flavour attributes (except for caramel-like in SDIT and bitter and after taste in DCIT) were not significantly different (p>0.05) among tea samples. The present study suggests that instant teas can also be used as good alternative to black tea.

Survey of tea for the presence of gluten

In 2013, the U.S. Food and Drug Administration conducted a survey of green and white teas marketed in the northeastern United States for the presence of undeclared wheat. Based on the requirement for concurrence between the RIDASCREEN gliadin (R5) enzyme-linked immunosorbent assay (ELISA) and the Morinaga Institutes of Biological Science (MIoBS) wheat protein ELISA, none of the 20 products included in the survey tested positive for wheat, rye, barley, or gluten. However, eight of the teas generated responses indicative of the presence of gluten with the RIDASCREEN gliadin (R5), AgraQuant gluten G12, and Aller-Tek (Skerritt) sandwich ELISAs. Five of the eight teas generated responses indicative of >20 ppm of gluten using the RIDASCREEN and AgraQuant ELISA test kits, and all eight had ≥ 20 ppm based on the Aller-Tek ELISA. Extracts prepared using the RIDASCREEN validated protocol and the MIoBS validated sodium dodecyl sulfate plus β-mercaptoethanol (overnight) protocol were analyzed using both test kits. The extracts prepared using the RIDASCREEN protocol tested positive for gluten with both test kits. Western blot analyses of the two sets of extracts using the R5 and MIoBS antibodies to visualize the bands revealed the presence of antigenic proteins in both sets of extracts, although the profiles and band intensities were different and inconsistent with the ELISA results. These results raise questions regarding the screening procedures used to detect gluten and how the observation of a homologous antigenic element is defined.

Nutritional composition and antioxidant capacity in edible flowers: characterisation of phenolic compounds by HPLC-DAD-ESI/MSn

Edible flowers are commonly used in human nutrition and their consumption has increased in recent years. The aim of this study was to ascertain the nutritional composition and the content and profile of phenolic compounds of three edible flowers, monks cress (Tropaeolum majus), marigold (Tagetes erecta) and paracress (Spilanthes oleracea), and to determine the relationship between the presence of phenolic compounds and the antioxidant capacity. Proximate composition, total dietary fibre (TDF) and minerals were analysed according to official methods: total phenolic compounds (TPC) were determined with Folin-Ciocalteu's reagent, whereas antioxidant capacity was evaluated using Trolox Equivalent Antioxidant Capacity (TEAC) and Oxygen Radical Absorbance Capacity (ORAC) assays. In addition, phenolic compounds were characterised by HPLC-DAD-MSn. In relation to the nutritional value, the edible flowers had a composition similar to that of other plant foods, with a high water and TDF content, low protein content and very low proportion of total fat-showing significant differences among samples. The levels of TPC compounds and the antioxidant capacity were significantly higher in T. erecta, followed by S. oleracea and T. majus. Thirty-nine different phenolic compounds were tentatively identified, with flavonols being the major compounds detected in all samples, followed by anthocyanins and hydroxycynnamic acid derivatives. In T. erecta small proportions of gallotannin and ellagic acid were also identified.