Total Catechins Research Articles

Integration of Metabolomics and Transcriptomics Reveal the Mechanism Underlying Accumulation of Flavonols in Albino Tea Leaves

Albino tea plants (Camellia sinensis) have been reported to possess highly inhibited metabolism of flavonoids compared to regular green tea leaves, which improves the quality of the tea made from these leaves. However, the mechanisms underlying the metabolism of catechins and flavonols in albino tea leaves have not been well elucidated. In this study, we analyzed a time series of leaf samples in the greening process from albino to green in a thermosensitive leaf-color tea mutant using metabolomics and transcriptomics. The total content of polyphenols dramatically decreased, while flavonols (such as rutin) were highly accumulated in albino leaves compared to in green leaves. After treatment with increasing environment temperature, total polyphenols and catechins were increased in albino mutant tea leaves; however, flavonols (especially ortho-dihydroxylated B-rings such as rutin) were decreased. Meanwhile, weighted gene co-expression network analysis of RNA-seq data suggested that the accumulation of flavonols was highly correlated with genes related to reactive oxygen species scavenging. Histochemical localization further demonstrated that this specific accumulation of flavonols might be related to their biological functions in stress tolerance. These findings suggest that the temperature-stimulated accumulation of total polyphenols and catechins in albino mutant tea leaves was highly induced by enhanced photosynthesis and accumulation of its products, while the initial accumulation and temperature inhibition of flavonols in albino mutant tea leaves were associated with metabolism related to oxidative stress. In conclusion, our results indicate that the biosynthesis of flavonoids could be driven by many different factors, including antioxidation and carbon skeleton storage, under favorable and unfavorable circumstances, respectively. This work provides new insights into the drivers of flavonoid biosynthesis in albino tea leaves, which will further help to increase tea quality by improving cultivation measures.

Effect and mechanism of exogenous selenium on selenium content and quality of fresh tea leaves

To study the effect and mechanism of selenium sources on the selenium content and quality of fresh tea leaves, tea seedlings (Camellia sinensis (L.) O. Kuntze) were the research object. A solution of 100 mg/L sodium selenate (Na2SeO4), sodium selenite (Na2SeO3), and selenium yeast (selenium yeast) were applied on the leaves surface of 5-week-old tea plants, and the selenium levels in the leaves, roots, and stems were determined at 20 weeks of age. The effects of different selenium sources on the mineral nutrient content, antioxidant enzyme activity, and quality parameters content in leaves were analyzed. The mechanism was analyzed by detecting the expression levels of related genes. The results showed that the three selenium sources can increase the growth of tea seedlings and the selenium content in leaves and stems, and the selenium yeast treatment had the most significant effect. Selenium spraying promoted the absorption of mineral nutrients such as nitrogen, phosphorus, and potassium, but had no significant impact on the absorption of calcium and magnesium. Spraying the three selenium sources dramatically increased the activities of APX, POD, and SOD antioxidant enzymes, among which the selenium yeast treatment had the most significant effect. However, there was no significant impact on the MDA level in this study. Selenium sources markedly increased leaves total amino acid levels, accompanied by up-regulation the genes of amino acid synthetic enzymes (CsGS, CsGOGAT, and CsGDH). Leaves glucose, tea polyphenol, total soluble protein, catechin, flavonoid contents, and sucrose were higher in selenium sources treatments than in control treatment seedlings. Moreover, selenium sources up-regulated expression of CsHMGR, CsAPX, and CsTCS1 genes. selenium yeast had the best comprehensive effect of the three selenium sources. These results confirmed that selenium sources play a positive role on the selenium content and quality of tea by increasing the antioxidant capacity of leaves, the absorption rate of mineral nutrients, and regulating expression of related genes in Camellia sinensis.

Analysis of a Special Sulphite-Producing Yeast Starter after Fermentation and during Wine Maturation

In the present study, we investigated the extent to which specific sulphur dioxide-producing wine yeasts produce SO2 during alcoholic fermentation and whether the SO2 they produce is sufficient to prevent oxidation during wine storage. Fermentation was carried out at 12 °C and 20 °C. After inoculation with yeast, the evolution of free and total sulphurous acid concentrations, acetaldehyde concentrations (11.6–46.9 mg L−1) and total polyphenol concentrations (137.4–244.7 mg L−1), including leucoanthocyanin and catechin concentrations (leucoanthocyanidin: 8.5–75.1 mg L−1; catechin: 70.8–115.4 mg L−1), were investigated during the storage of fermented wines. The amount of free sulphur dioxide was measured between 5 and 10 mg L−1. Total sulphuric acid ranged from 6 to 22 mg L−1, taking into account the results of the three years studied. The aim of our tests was to observe whether the use of sulphur-producing yeasts during the ageing of fermented wines showed any benefit. The results of all three vintages tested showed that neither the 12 °C nor the 20 °C fermented batches showed any advantage in using sulphur dioxide-producing yeasts. Our results show that there is no clear evidence that the yeast produces sufficient sulphur dioxide during fermentation and that there is no clear demonstrable benefit from its use.

Chemical components in yellow mealworm (Tenebrio molitor L.) reared with tea powder

The research highlights of the manuscript are as follows: • Tea powder was used for the first time to rear yellow mealworms. • Yellow mealworms can grow well by tea powder rearing. • The content of the function components such as tea polyphenols, total Catechins, Catechin(C), Epicatechins(EC), Epigallocatechins(EGC), Epicatechin gallates(ECG), and Epigallocatechin gallates(EGCG),as well as the nutrition component protein, were all significantly increased along with the increased ratio of tea powder. • Reared with tea powder, the yellow mealworm grow well with protein and fatty acid changing for suitable for human being health. • Yellow mealworm reared with tea powder can be a kind of good potential food for people. The yellow mealworms ( Tenebrio molitor L .) were reared by different ratios of tea powder and wheat bran powder mixtures, and weighted every day during the whole 10 days rearing. The content of tea polyphenols, total catechins, catechin (C), epicatechins (EC), epigallocatechins (EGC), epicatechin gallates (ECG), epigallocatechin gallates (EGCG), and nutrition components such as protein and fatty acid in the yellow mealworms were determined after 10 days rearing. The yellow mealworms can put on weight and grow well when the proportion of tea powder belows 80%, while 100% tea powder rearing has no signifi cantly reduced the weight of yellow mealworms. The content of tea polyphenols, total catechins, C, EC, EGC, ECG, and EGCG all enhance signifi cantly along with the increase ratio of the tea powder. The protein content increase more signifi cantly at 50% and 80% ratios treatments than the other treatments. Tea powder added rearing reduces the content of saturated fatty acid, and has a complex effect on the content of unsaturated fatty acid. Comprehensive analysis of the components determined show that 50% ratio is the best for yellow mealworm rearing.

Solubilization and extraction of valuable compounds from peanut skin in subcritical water

Subcritical water extraction (SWE) is a process for extracting valuable compounds of catechin and epicatechin from the skin of the peanut (Arachis hypogea). The research's objective was to identify the best extraction conditions for recovering total catechin compounds (TCC), total epicatechin compounds (TEC), and total yield from peanut skin. The solubility of yield in subcritical water was determined using the Chrastil and Del Valle Aguilera models. The best conditions were 13.56 MPa, 11.66 ml/min, 160°C with responses of TCC 10.81 mg/g, TEC 8.41 mg/g, and yield 0.268 g/g. High pressure and temperature conditions were conducive to TEC recovery, whereas high flow rate conditions were suitable to TEC and total yield enhancement. The Chrastil model fits the solubility of yield in subcritical water effectively since it has the lower average absolute relative deviation, which is 85.507% compared to Del Valle Aguilera of 85.509%. The Chrastil and Del Valle Aguilera model was not suitable for the solubility of peanut skin extract due to high percentage of AARD. Practical applications The catechin and epicatechin from peanut skin were frequently recovered using a hazardous solvent in a traditional extraction procedure. Subcritical water extraction is one of the methods for overcoming the toxicity of solvents. The best condition for obtaining maximum total catechin compounds (TCC), total epicatechin compounds (TEC) was determined using response surface methodology. Furthermore, in this work, a semi-empirical model was utilized to evaluate the effect of parameters to improve the solubility of bioactive compounds. TEC recovery was enhanced by high pressure and temperature, while TEC and total yield augmentation were enhanced by high flow rate.

Chemical composition and anti-inflammatory activity of water extract from black cocoa tea (Camellia ptilophylla)

Cocoa tea (Camellia ptilophylla) is a non-conventional tea variety with low caffeine and high gallocatechin gallate (GCG). The anti-inflammatory activity of black cocoa tea and its underlying mechanisms remain virtually unknown. In this study, the chemical composition and anti-inflammatory activity of water extracts from black cocoa tea (BCWE) and Yunnan Daye tea (BYWE) were compared. Results showed that the dominant alkaloid in BCWE and BYWE were theobromine and caffeine, respectively. The contents of gallic acid, total catechins, and total polyphenols in BCWE were significantly higher than those in BYWE. For tea pigments, BYWE contained a little more total theaflavins and theabrownins than BCWE, while no significant difference was observed in thearubigins. Interestingly, a novel theaflavin synthesized from GCG and catechin was found in BCWE. In lipopolysaccharide-induced RAW264.7 cells, both BCWE and BYWE could inhibit the production of nitric oxide and prostaglandin E2 by down-regulating the expression levels of inducible nitric oxide synthase and cyclooxygenase-2. They also markedly reduced the release of tumor necrosis factor-α and interleukin-6 at a high dose. Additionally, BCWE exhibited stronger anti-inflammatory activity than BYWE. Finally, BCWE exerted anti-inflammatory effect by inhibiting the activation of mitogen-activated protein kinases, phosphatidylinositol-3-kinase/protein kinase B, and nuclear factor-kappa B signaling pathways. These findings suggest that black cocoa tea can be developed into a promising functional beverage with anti-inflammatory property.

Coffee Leaf Tea from El Salvador: On-Site Production Considering Influences of Processing on Chemical Composition.

The production of coffee leaf tea (Coffea arabica) in El Salvador and the influences of processing steps on non-volatile compounds and volatile aroma-active compounds were investigated. The tea was produced according to the process steps of conventional tea (Camellia sinensis) with the available possibilities on the farm. Influencing factors were the leaf type (old, young, yellow, shoots), processing (blending, cutting, rolling, freezing, steaming), drying (sun drying, oven drying, roasting) and fermentation (wild, yeast, Lactobacillus). Subsequently, the samples were analysed for the maximum levels of caffeine, chlorogenic acid, and epigallocatechin gallate permitted by the European Commission. The caffeine content ranged between 0.37–1.33 g/100 g dry mass (DM), the chlorogenic acid was between not detectable and 9.35 g/100 g DM and epigallocatechin gallate could not be detected at all. Furthermore, water content, essential oil, ash content, total polyphenols, total catechins, organic acids, and trigonelline were determined. Gas chromatography—mass spectrometry—olfactometry and calculation of the odour activity values (OAVs) were carried out to determine the main aroma-active compounds, which are β-ionone (honey-like, OAV 132-927), decanal (citrus-like, floral, OAV 14-301), α-ionone (floral, OAV 30-100), (E,Z)-2,6-nonadienal (cucumber-like, OAV 18-256), 2,4-nonadienal (melon-like, OAV 2-18), octanal (fruity, OAV 7-23), (E)-2 nonenal (citrus-like, OAV 1-11), hexanal (grassy, OAV 1-10), and 4-heptenal (green, OAV 1-9). The data obtained in this study may help to adjust process parameters directly to consumer preferences and allow coffee farmers to earn an extra income from this by-product.

Molecular Link in Flavonoid and Amino Acid Biosynthesis Contributes to the Flavor of Changqing Tea in Different Seasons.

The present study was aimed to elucidate the flavor formation mechanism of Changqing tea. High-performance liquid chromatography (HPLC) analysis showed that the total catechins of Changqing tea was 65–160 mg/g, with 16–34 mg/g non-galloyated catechins and 49–126 mg/g galloylated catechins. Tea polyphenols and free amino acids account for 286–312 mg/g and 35–89 mg/g, respectively. Transcriptome of Changqing tea during different seasons revealed 316, 130 and 12 DEGs in comparisons of spring vs. autumn, spring vs. summer, and summer vs. autumn, respectively. Compared to spring, the genes involved in flavonoid biosynthesis and bitter imparted amino acids were up-regulated in summer and autumn. Metabolome analysis was conducted by using HPLC-MS; the result indicated that umami and kokumi contributing amino acids were decreased in summer and autumn compared with spring. It could be concluded that the coordination of flavonoid biosynthesis and amino acids biosynthesis resulted in the special flavor of Changqing tea.

건조방식에 따른 홍차의 성분과 맛 차이

The traditional black tea, called Jeaksal, has made by the method of oxidation under sunlight and consumed in the Hadong region from the past. This study compared the ingredients and quality (taste) of black tea according to drying methods. The highest and lowest levels of the caffeine were obtained in the black tea sun drying (BTSD, 1.93%), and black tea shade drying (BTSHD, 1.73%), respectively, as opposed to the highest total catechin levels in the BTSD (3.31%) and the lowest in the BTSHD (0.78%). The highest theaflavin content was detected in the black tea (BT) (control, 0.66%). We further confirmed that the free amino acid content decreased with delayed drying time and temperature. Total free amino acid was detected by the highest value in BTSD with 24.91 mg/g, but by lowest value in BTSHD with 11.45 mg/g. In the shade drying 'Jeaksal' sour, bitter and astringent taste were strongly detected, whereas salty, umami, richness (after-umami) taste were weakly measured. BT and black tea pot drying (BTPD) has a similar taste pattern overall because of the same pot-drying method.

Effects of fermentation time on phenolic composition, antioxidant and antimicrobial activities of green, oolong, and black teas

In this study, it was aimed to investigate the effect of fermentation degree on total phenolic content, individual catechins, gallic acid, theaflavins, caffeine content, antioxidant and antimicrobial activity in teas. Green tea, black tea and oolong tea (partially oxidized 7 different degrees) were produced from the same cultivar of tea leaves harvested in first shooting period. The higher degree of fermentation was resulted in higher theaflavins, however in lower individual catechins and total phenolic content. Standard catechins gradually decreased with extended fermentation duration and epigallocatechin gallate decreased 87% from green tea to oolong to black tea. Higher antioxidant activity was observed in green and lower fermented oolong teas. There were significant (p<0.01) positive correlations (r2>0.9) between DPPH, ABTS assays and total phenolic content, catechin, epigallocatechin gallate, epicatechin, epicatechin gallate and total catechins. Significant (p<0.05), positive correlations (r2>0.7) were also observed between ORAC and those catechins. Moreover, the tea samples especially green tea showed antibacterial effects against three of the tested pathogenic bacteria Staphylococcus aureus ATCC 29213, Enterococcus faecalis ATCC 29212, Pseudomonas aeruginosa ATCC 27853 and antifungal effects against Candida albicans ATCC 10231. However, no antimicrobial activity was detected against Escherichia coli.

Comprehensive investigation on non-volatile and volatile metabolites in four types of green teas obtained from the same tea cultivar of Longjing 43 (Camellia sinensis var. sinensis) using the widely targeted metabolomics

In this study, we produced roasted, baked, steamed, and sun-dried green tea products using the same batch of fresh tea leaves (FTL) of Longjing 43 (Camellia sinensis var. sinensis), and explored processing effects on the metabolic profiles of four types of green teas (FGTs) using the widely targeted metabolomics. Results showed that 146 differential metabolites including flavonoids, amino acids, lipids, and phenolic acids were screened among 1034 non-volatiles. In addition, nineteen differential metabolites were screened among 79 volatiles. Most of non-volatiles and volatiles metabolites changed notably in different manufacturing processes, whereas there were no significant differences (p＞0.05) in the levels of total catechins between FGTs and FTL. The transformation of metabolites was the dominant trend during green tea processing. The results contribute to a better understanding of how the manufacturing process influences green tea quality, and provide useful information for the enrichment of tea biochemistry theory.

Establishment of a rapid detection model for the sensory quality and components of Yuezhou Longjing tea using near-infrared spectroscopy

Quantitative prediction models for sensory quality scores, total catechins, and caffeine based on near-infrared spectroscopy were established for different quality grades of Yuezhou Longjing tea. One-way ANOVA and multiple comparison test analyses were first conducted on the obtained sensory quality scores and physical and chemical quality indices to check the accuracy and reliability of the experimental data. There were significant differences in the sensory quality, total catechins, and caffeine of different grades of tea. Secondly, the obtained near-infrared spectrum data were preprocessed, and then the competitive adaptive reweighted sampling (CARS) and variables combination population analysis combined with iterative retained information variable algorithm (VCPA-IRIV) were used to screen the optimal characteristic wavenumbers of each quality index. Along with principal component analysis (PCA) to establish prediction models for the partial least squares regression (PLSR), support vector regression (SVR), and random forest algorithm (RF). The results showed that the best predictive models for sensory scores, total catechins, and caffeine were VCPA-IRIV + SVR, VCPA-IRIV + RF, and CARS + SVR, and the relative percent deviation (RPD) were 2.485, 2.584, and 2.873, respectively. Indicates that the model has good predictive performance. In conclusion, it is feasible to evaluate the quality of Yuezhou Longjing tea with near-infrared spectroscopy.

A Green Tea Extract-Rich Confection in Healthy and Metabolic Syndrome Adults Decreases Small Intestinal Permeability in Association With Lower Gut Inflammation

ObjectivesPoor gut health, including increased intestinal permeability and inflammation, enhances cardiometabolic risk. Catechin-rich green tea extract (GTE) alleviates cardiometabolic complications in obese rodents by limiting gut permeability and inflammation, but whether these benefits occur in humans is not known. We hypothesized that the anti-inflammatory activities of GTE would decrease gut barrier dysfunction in persons at heightened cardiometabolic risk. MethodsIn a randomized, double-blind, placebo-controlled crossover study, persons with metabolic syndrome (MetS) and healthy persons completed two 4-wk interventions in which they received placebo or GTE confections (890 mg/d total catechins) while following a low-polyphenol diet. At wk 4, participants provided fecal samples for ELISA-based measures of inflammatory proteins. 24-h urine samples were also collected for LC/MS analysis of non-digestible sugars following the ingestion of lactulose (LAC), mannitol (MAN), sucralose (SUC), and erythritol (ERY). Data were analyzed by repeated measures ANOVA and linear regression controlling for within-subject repeated measures. ResultsMetS (n = 21; 40 ± 3 y; 35.2 ± 1.0 kg/m2) and healthy (n = 19; 34 ± 2 y; BMI = 22.3 ± 0.4 kg/m2) adults completed the study with no adverse effects, no changes in liver function tests, and > 95% compliance based on returned confections. Urinary SUC/ERY was unaffected by GTE and health status, but urinary LAC/MAN was lower (P = 0.043) in GTE compared with placebo regardless of health status. Fecal myeloperoxidase and calprotectin did not differ by health status, but were lower (P = 0.03–0.05) in response to GTE regardless of health status, and were positively correlated with each other (r = 0.75; P < 0.001). Fecal calprotectin and myeloperoxidase were both positively correlated with LAC/MAN ratio (r = 0.39–0.42; P = 0.01–0.02). ConclusionsInterim findings of this study support that dietary GTE decreases small intestinal permeability in association with lower gut inflammation, which may help to explain its known cardiometabolic benefits. Funding SourcesUSDA-NIFA (2019–67,017-29,259), USDA-HATCH, and the Ohio Agricultural Research and Development Center at The Ohio State University.

Investigation of the Azorean Camellia sinensis Processing Conditions to Maximize the Theaflavin 3,3'-di-O-Gallate Content as a Potential Antiviral Compound.

The molecular constituents of Camellia sinensis, in particular epigallocatechin-3-O-gallate (EGCG) and, more remarkably, the galloylated theaflavins, mainly theaflavin-3,3′-di-O-gallate (TF-3,3′-DG), have been reported to inhibit SARS-CoV-2 3-chymotrypsin-like protease (3CLpro), an enzyme required for the cleavage of its polyproteins, to produce vital individual functional proteins for viral cell replication. Our results for total catechin content revealed the values of 174.72, 200.90, and 211.75 mg/g dry weight (DW) in spring, and the values of 183.59, 191.36, and 215.09 mg/g DW in summer, for tea plantation zones 1, 2, and 3, respectively. For the TF-3,3′-DG content, the values of 2.68, 1.13, and 3.72 mg/g DW were observed in spring, and the values of 3.78, 2.06, and 8.91 mg/g DW in summer for zones 1, 2, and 3, respectively. In the same zone, different contents of TF-3,3′-DG were observed across plucking months of April, June, and August, with values of 1.13, 2.77, and 4.18 mg/g DW, respectively, showing higher values in summer. Different values of TF-3,3′-DG contents were also observed in the same tea plantation zone but from different plant parts, revealing higher values in the bud and the first and second leaves (3.62 mg/g DW) and lower values in the third and fourth leaves (1.14 mg/g DW). The TF-3,3′-DG content increased from 3.31 to 4.98 mg/g DW with increased fermentation time from 1 to 3 h, respectively, and increased for lower temperature and longer fermentation time. The aim of this study was to investigate the processing conditions that lead to maximum TF-3,3′-DG content and, given its potential impact as an inhibitor of the 3CLpro enzyme, to create a novel antiviral Azorean black tea.

Comparison of the Fungal Community, Chemical Composition, Antioxidant Activity, and Taste Characteristics of Fu Brick Tea in Different Regions of China.

In this study, the fungal community structure, metabolites, antioxidant ability, and taste characteristics of five Fu brick tea (FBT) from different regions of China were determined and compared. A total of 69 operational taxonomic units (OTUs) were identified and assigned into 5 phyla and 27 genera, with Eurotium as the predominant genus in all samples. Hunan (HN) sample had the strongest fungal diversity and richness, followed by Guangxi (GX) sample, and Zhejiang (ZJ) sample had the lowest. GX sample had higher amounts of gallic acid (GA), total catechins, gallocatechin (GC), and epicatechin gallate (ECG) as well as antioxidant activity than the other samples. The levels of total phenolics, total flavonoids, epigallocatechin (EGC), catechin, epicatechin (EC), thearubigins (TRs), and theaflavins (TFs) were the highest in the ZJ sample. Guizhou (GZ) and Shaanxi (SX) samples contained the highest contents of epigallocatechin gallate (EGCG) and gallocatechin gallate (GCG), respectively. Total phenolics, GA, EC, CG, and TFs were positively associated with most of fungal genera. Total phenolic content (TPC), total flavonoid content (TFC), and most of catechins contributed to the antioxidant activities of FBT. HN sample had the strongest sourness and sweetness, ZJ sample had the strongest saltiness, SX sample had the strongest umami, and GZ sample had the strongest astringency, which was ascribed to the varied metabolites. This work reveals that FBT in different regions vary greatly in fungal community, metabolites, antioxidant activity, and taste characteristics, and provides new insight into the quality characteristics formation of FBT in different regions.

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.

Assessment of changes in microbiological, physicochemical, and sensory qualities of γ‐irradiated strawberries ( Fragaria × ananassa Duch. “Maehyang”) during storage

In this study, the effects of γ-irradiation at 0.15–0.9 kGy on the quality attributes of ‘Maehyang’ strawberries were evaluated. Both the irradiation dose and storage period affected the physicochemical properties of the fruit, such as pH, total soluble solids, and titratable acidity in the γ-irradiated samples compared with those in the control, but the difference was not significant (p < 0.05). The irradiation samples showed dose-dependent decreases in decay incidence, weight loss, microbial burden, hydrogen peroxide, and malondialdehyde levels. Although total phenolic content, ellagic acid, catechin, pelargonidin, and antioxidant activity increased gradually during storage regardless of irradiation, these parameters changes were delayed in strawberries irradiated at 0.9 kGy; furthermore, they had the highest overall acceptance sensory scores after storage and lowest rates of firmness loss and color-change deterioration. γ-irradiation at 0.9 kGy is thus sufficient for phytosanitary purposes, as it extends shelf life and maintains sensory qualities of strawberries.

Manipulation of the Phenolic Quality of Assam Green Tea through Thermal Regulation and Utilization of Microwave and Ultrasonic Extraction Techniques

The aim of this study was to investigate the catechin levels and antioxidant activities as manipulated by roasting temperature and roasting time of green tea. Roasting temperature and time varied between 100–300 °C and 60–240 s in green tea production. The main interactions measured were effects on the antioxidant activities, total phenolic content, DPPH, ABTS, FRAP and catechin content (catechin (C), epigallocatechin gallate (EGCG), epigallocatechin (EGC), epicatechin gallate (ECG) and epicatechin (EC)). Optimum roasting conditions were determined as 270 °C for 240 s, since this enabled high catechin contents, antioxidant activities and production yield. The extraction methods for green tea including traditional extraction (TDE), microwave-assisted extraction (MAE) and ultrasonic-assisted extraction (UAE) using 60% ethanol as solvent were investigated to evaluate the highest bioactive compound and yield of extraction. MAE was found to be more efficient in green tea extraction compared to UAE and TDE. The extracts showed significant cytotoxic potential against the Huh-7 cell line, in concentrations ranging from 31.25 to 1000 µg/mL. The results are useful in understanding the relationship between thermal treatment and extraction conditions on the chemical and nutritional properties of tea catechins, making it possible to select the production and extraction conditions that maximize the levels of beneficial tea ingredients.

Antioxidant activity, polyphenolic composition and in vitro antibacterial and antifungal activities of tea seed oil

The polyphenolic composition and antioxidant activity of tea seed oil from C. sinensis TRFK 301/5 (green colored) and TRFK 306 (purple colored) and C. oleifera were evaluated. The total polyphenolic content, total catechins and catechin fractions were significantly different in the oils. C. oleifera contained significantly (p ≤ 0.05) higher amounts of catechins and polyphenols than C. sinensis. C. oleifera also exhibited a higher DPPH radical scavenging activity (18.81 ± 0.46%) compared to C. sinensis (TRFK 306; 15.98 ± 0.13 and TRFK 301/5; 14.73 ± 0.47%). The antimicrobial activities of tea seed oil and two selected oils (olive and eucalyptus oil), were also evaluated against Escherichia coli, Staphylococcus aureus, Candinda albicans, Cryptococcus neoformans and Trichophyton mentagrophytes. S. aureus was significantly inhibited by the oils compared to E. coli. The oils inhibited the growth of T. mentagrophytes and C. albicans, although they had no effect on C. neoformans. Tea seed oil is a potential source of beneficial phytochemicals and potent antimicrobial agents.

Effects of altitude on the chemical composition of grapes and wine: a review

Of the geographical parameters in a winegrowing site, altitude is an important determinant of wine composition and quality. Grape polyphenols and volatiles comprise a large and varied group of compounds that contribute considerably to the sensory and health-promoting properties of wine. This review surveys the impacts of altitude and its related climatic characteristics on the phenolic and aroma compounds of grapes and wine through the examination of existing literature. Furthermore, this review highlights the challenge of distinguishing the effects of parameters, such as air temperature, variety, vine water status, soil and UV radiation, from the altitude effect. Overall, high-altitude growing sites can favour an increase - albeit at different intensities - in content of many chemical compounds found in grapes and wine, such as total polyphenols, total monomeric anthocyanins, catechins, quercetin derivatives and cyanidin-derived anthocyanins, trihydroxylated flavonols, carotenoids, isoamyl acetate and ethyl hexanoate. However, the altitude factor seems to be cultivar-dependent; in fact, it can exert a positive effect on the concentrations of acylated anthocyanins and of total aroma compounds in some cultivars (e.g., Ekşikara and Glera) and a negative effect on the same components in other cultivars (e.g., Merlot and Cabernet-Sauvignon). Its influence on the polyphenol content can also differ between different parts of the same cultivar; for instance, an increase in skin tannins and a decrease in seed tannins have been found to be concomitant with an increase in altitude in Syrah grapes. Moreover, at higher altitude, the effect of an increase in UV-B radiation can lead to an enhancement in colour intensity due to an increase in the synthesis of anthocyanins, flavonols and tannins. Due to their cool climate, high-elevated winegrowing regions represent favourite cultivation sites under current and future global warming.