Tea Preparation Research Articles

Effect of Green, Tulsi, and Areca Teas on the Color Stability of Two Composite Resin Materials - an in vitro Spectrophotometric Analysis.

ObjectiveTo compare the effect of Green, Tulsi, and Areca teas on the color stability of two composite materials on the 30th and 60th days.Materials and MethodsTwo light cure composite restorative materials, Brilliant EverGlow (Group 1) and Brilliant NG, (Group 2) with different resin and filler characteristics were selected. The test solutions selected were Green tea, Tulsi tea, Areca tea, and artificial saliva (control group). In total, 104-disc shaped specimens were fabricated using a custom made brass mold as per the manufacturer instructions. All specimens were put in storage for rehydration and complete polymerization at 37°C in distilled water for 24 hours. Specimens of each composite material were randomly divided into four subgroups of 13 samples. Tea solutions were freshly prepared, and specimens were immersed in the respective solutions every day for 15 minutes for 60 days. Specimens were stored in artificial saliva after the immersion regimen. The color evaluation was done before immersion, on the 30th and 60th day, using a digital reflectance spectrophotometer.ResultsAt 30 days, Group 1 specimens immersed in Areca and Green teas showed significantly higher mean values than those in control and Tulsi tea. At 60 days in Group 1, specimens in Areca tea showed significantly higher mean value, followed by Green tea, Tulsi tea, and control. At 30 and 60 days in group 2, specimens in control had significantly lower mean values than other tea preparations. Group 1 showed a higher mean difference in ΔE than Group 2 specimens immersed in Green and Areca teas at 30 days (P=0.001 and 0.001) and 60 days (P=0.001 and <0.001), respectively.ConclusionAll herbal tea preparations exhibited staining potential, which increased over time, and Areca tea showed the highest staining potential. Understanding the staining potential of newer tea preparations on recent composite materials helps the clinician to choose the right restorative materials.

Phenolic antioxidants of bael fruit herbal tea and effects on postprandial glycemia and plasma antioxidant status in healthy adults

Herbal teas are globally popular among health conscious consumers. In this study the phenolic content and potential antioxidant activities of bael fruit herbal tea prepared with dried immature bael fruit cuts (Aegle marmelos), traditionally used in the Asia, were determined. Phenolic compounds of the herbal extracts were identified using liquid chromatography-tandem mass spectrometry. The total phenolic content (TPC) and antioxidant activities of the tested herbal extract was determined. The amount of herbal material to be used in the tea preparation was established based on the sensory evaluation conducted with 50 untrained adult panelists. The single dose efficacy of the bael fruit herbal tea on postprandial glycemic response and plasma antioxidant capacity (PAC) of healthy adults were investigated. A randomized crossover study was carried out with 16 healthy adults who consumed 250 mL bael fruit tea with 50 g glucose challenge and the control (50 g glucose in 250 mL water) randomly within two visits. Blood samples were collected at the baseline and postprandial at 30, 45, 60, 90, and 120 min using microcapillary tubes. The plasma was analyzed for glucose concentration (PGC) and PAC. The TPC of bael fruit tea extract was 108.3 μmol gallic acid equivalents/g of extract. There was a reduction trend in mean PGC of those subjects who consumed bael fruit tea compared to the glucose added water (control) at each time point. Furthermore, the bael fruit tea significantly increased PAC at the end of 120 min post ingestion. Further research is warranted to examine the long-term efficacy of multiple dose ingestion of bael fruit herbal tea in the control and management of diseases associated with oxidative stress.

Phytochemical profile of Anacardium occidentale L. (cashew tree) and the cytotoxic and toxicological evaluation of its bark and leaf extracts

Anacardium occidentale (Anacardiaceae), popularly known as cashews, is a vegetable native to South America, consumed worldwide in the food sector. Its leaves and bark are used in the preparation of teas for health maintenance, being indicated in ethnobotanical studies for the treatment of cancer, which is considered a serious public health problem worldwide. The objective of this study was to evaluate the cytotoxicity of the A. occidentale leaf and bark extracts over tumor and normal cells, as well as their in vivo toxicity using the Drosophila melanogaster fruit fly. Cytotoxicity was evaluated using the MTT method [3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazol bromide] in five cell lines (HL-60, NCI-H292, HCT-116, P815 and L929). Toxicity was evaluated by fly mortality rate and negative geotaxis, as well as by oxidative stress markers (Fe2+ quantification, protein and non-protein thiols) in the D. melanogaster model. The chromatographic study was performed by UPLC-QTOF/MS. As a result, 11 compounds present in the A. occidentale leaf extract (LEAo) and 6 compounds in the bark extract (BEAo) were identified, with gallic acid and galloyl hexoside being present in both samples. The bark extract presented a greater cytotoxic activity for HCT-116, HL60 and P815 tumor cells. The extracts also presented a low cytotoxicity with the normal cell line, L929. No changes in the levels of protein and non-protein thiols (NPSH) were observed, whereas a considerable increase in Fe2+ levels was observed in the Fe2+ quantification assays from homogenized flies exposed to the leaf extract in the D. melanogaster assays. However, further in-depth studies need to be carried out to elucidate the mechanisms of action of the extracts and to assess their pharmacological safety.

Influência do tempo de infusão nas características físico-químicas e no conteúdo de compostos bioativos nutracêuticos de folha de mangaba (Hancornia speciosa Gomes)

A folhas da mangabeira são popularmente utilizadas no preparo de chás e infusões com fins medicinais. Infusões de ervas apresentam propriedades benéficas devido as substâncias bioativas que atuam como antioxidantes. Assim, o objetivo desse estudo foi avaliar as características físico-químicas e o conteúdo de compostos bioativos nutracêuticos e, verificar a influência do tempo em infusões de folhas de mangaba. As infusões foram preparadas em triplicada a 5 e 10 (I5 e I10) minutos, adicionando 1 g de material vegetal in natura em 50 mL de água fervente. Foram efetuadas análises para caracterização físico-química das folhas in natura, infusões e resíduos: cor e índice de escurecimento (I.E.); sólidos solúveis totais em ºBrix e; pH. As análises dos compostos bioativos foram: clorofilas, carotenóides e fenóis totais. Nas análises físico-químicas, o teor de sólidos solúveis totais não variou significativamente, indicando que os tempos analisados extraíram conteúdos similares. O I.E. permaneceu constante, indicando que o tratamento térmico não foi associado com a ativação enzimática e escurecimento. Entretanto, o tempo de infusão afetou significativamente os fitoquímicos. Os valores de clorofila total e suas frações variaram com diminuição progressiva em comparação da folha in natura em diferentes tempos de infusão, bem como os carotenóides totais, β-caroteno e fenóis, o que sugere influência do tempo na quantidade desses compostos presentes nas infusões, sendo que, a I5 proporcionou menor perda dos compostos comparado à I10, podendo correlacionar-se positivamente com a concentração de flavonóides e com a atividade antioxidante.

Modeling of drying and rehydration kinetics ofRosa pimpinellifoliafruits: Toward formulation and optimization of a new tea with high antioxidant properties

AbstractRosa pimpinellifoliais the black of rosehips having many uses in the food and pharmaceutical industries. The modeling of drying and rehydration kinetics of the fruits as well as the optimization of preparation conditions of a new tea was investigated. Empirical models were applied to predict the drying and rehydration behaviors ofR. pimpinellifoliafruits. Response surface methodology was used to optimize the tea preparation together with antioxidant properties. The analysis of drying behavior of the fruits revealed that they dried faster at higher temperatures (70–90°C/1.75 m/s); however, the antioxidant properties were most preserved at 70°C. Midilli model was the best‐fitted model describing the drying kinetic of the fruits. The rehydration capacity was more effective at 60°C compared to 20 and 40°C. Peleg, Vega‐Gálvez, and Weibull models depicted better the rehydration behavior of these fruits. The teas were prepared with the fruits dried that 70°C/1.75 m/s since they displayed the highest antioxidant properties. The optimum conditions were 15 min decoction time and 1.5 g solid‐to‐liquid ratio. Higher antioxidant properties were observed inR. pimpinellifoliatea when compared to fresh and dried fruit. These findings showed thatR. pimpinellifoliafruits are valuables as an industrial product.Practical ApplicationsThe drying conditions to have a dried fruit with high antioxidant properties were determined. The dried food is afforded in off‐seasons. Mathematical models were successfully applied to describe the drying and rehydration kinetics ofR. pimpinellifolia. Midilli model was the most fitted model to predict the drying kinetics ofR. pimpinellifolia. Peleg, Vega‐Gálvez, and Weibull models depicted better the rehydration kinetics ofR. pimpinellifoliaat 20, 40, and 60°C. A new fruit tea was formulated from the dried fruits. This tea is a functional food having great antioxidant properties.

Chemical Profile and Biological Activity of Cherimoya (Annona cherimola Mill.) and Atemoya (Annona atemoya) Leaves.

Annona cherimola (Cherimoya) and Annona atemoya (Atemoya) are tropical plants known for their edible fruit. Scientific data suggest that their leaves, used in traditional medicine in the form of teas or infusions without evidence of toxicity, contain several bioactive compounds. However, only Annona muricata among all the Annona species is currently used in the nutraceutical field, and its dried leaves are marketed for tea preparation. In this work, we explored the nutraceutical potential of Atemoya and Cherimoya leaves, by evaluating their chemical profile and functional properties. Phytochemical analyses showed large amounts of phenolic compounds, in particular proanthocyanidins, and identified 18 compounds, either flavonoids or alkaloids. Concerning biological activity, we found antioxidative properties correlated with polyphenols, and antiproliferative activity against HeLa and HepG2 cell lines correlated with alkaloids. The obtained results demonstrate the potential use of Annona cherimola leaves for the preparation of dietary supplements aimed to promote the physiological redox balance. Moreover, the varietal comparison suggests that two commercial cultivars (Campas and White) and the local Torre 1, better suit this purpose. On the other hand, among the studied cultivars, Campas and Torre 1 are also the richest in alkaloids and, in consideration of the anti-proliferative properties of their extracts, dietary supplements based on these cultivars might also have chemo-preventive effects.

A BIOPROCESS DEVELOPMENT STUDY OF POLYPHENOL PROFILE, ANTIOXIDANT AND ANTIMICROBIAL ACTIVITIES OF KOMBUCHA ENRICHED WITH Psidium guajava L.

Kombucha has become a flavored tea drink fermented with a symbiotic community of fungi, yeast, and bacteria. Kombucha has been reported to show functional medicinal importance attributed to the presence of some critical metabolites and bioactive compounds. We developed kombucha on three different substrates like black tea, green tea, and Psidium guajava (guava) juice extract. Kombucha enriched with guava extract showed maximal growth in terms of weight (fresh and dry) and moisture percentage. Further, the total phenol, total flavonoid, and characterization of different phenolic compounds like gallic acid, catechin, guaiacol and coumaric acid with guava juice extract fermented kombucha exhibiting maximal production. Also, the high DPPH (2,2-diphenyl-1-picryl-hydrazyl-hydrate) radical scavenging activity over the control. The kombucha tea fermented on guava extract showed significant antimicrobial activity against eleven human pathogenic bacterial strains and four pathogenic fungi. From the current study, we conclude that the preparation of kombucha tea using guava juice extract might be used as a supplementary food product due to its high nutritional value.

Bioactive platycodins from Platycodonis Radix: Phytochemistry, pharmacological activities, toxicology and pharmacokinetics

Platycodonis Radix, the root of Platycodon grandiflorum (Jacq.) A. DC., is a well-known edible herbal medicine. It is a common vegetable used for the preparation of side dish, kimchi, dessert, and tea. Besides, it has been used to treat respiratory disease including cough, excessive phlegm, and sore throat for a long history. In the past decades, the bioactive components and the pharmacological activities of Platycodonis Radix have been widely investigated. Thereinto, platycodins, the oleanane-type triterpenoid saponins were demonstrated to be the main bioactive components in Platycodonis Radix, and more than 70 platycodins have been identified up to date. This paper mainly reviewed the phytochemistry, pharmacological activities (apophlegmatic, anti-tussive, anti-inflammatory, anti-cancer, anti-obesity, anti-diabetic, immunomodulatory, cardiovascular protective, and hepatoprotective activities, etc.), toxicology and pharmacokinetics of platycodins isolated from Platycodonis Radix, aiming to promote further investigation on therapeutic potential of these platycodins.

ФИЛОСОФИЯ И АРХИТЕКТУРА ЧАЙНЫХ ДОМИКОВ ЯПОНИИ

ФИЛОСОФИЯ И АРХИТЕКТУРА ЧАЙНЫХ ДОМИКОВ ЯПОНИИ

Effect of freezing treatment in tea preparation using Camellia sinensis leaves.

This study was conducted to examine the effect of freezing in the tea preparation using Camellia sinensis leaves in order to develop new technology for improving tea quality. Effects of single and combined treatments of freezing (F: - 20°C, 15days), steaming (S: 100°C, 3min), and hot-air drying (HD: 50°C, 12h) on the physicochemical characteristics of tea (powder and hot-water leachate) prepared from treated Camellia sinensis leaves were investigated. The L * , b * , and C * values of the powder were the highest in SHD-treated leaves, followed by HD-, SFHD-, and FHD-treated leaves. Redness (+a * value) was only seen in FHD-treated leaves and greenness (- a * value) was the highest in SHD-treated leaves. Browning index of the leachate was significantly lower in SHD- and SFHD-treated leaves than in FHD-treated leaves (p < 0.05). Soluble solids, acidity, and phenolic compounds of FHD-treated leaves were significantly lower than in SHD- and SFHD-treated leaves (p < 0.05). Sucrose was highest in SHD-treated leaves and glucose was highest in FHD-treated leaves. Sensory preference was better evaluated in FHD-treated leaves than in SHD- and SFHD-treated leaves. These results suggest that freezing treatment in tea processing promotes browning and component decomposition and enhances sensual preference. Therefore, freezing has a potential application in the tea manufacturing.

Retraction: Epigallocatechin gallate effectively ameliorates fluoride-induced oxidative stress and DNA damage in the liver of rats

Environmental exposure to sodium fluoride (NaF) compounds is a worldwide health concern. Epigallocatechin gallate (EGCG) is a green tea catechin found in a variety of green tea preparations. The intention of this study was to investigate the hepatoprotective role of EGCG in NaF-intoxicated rats. Rats were orally treated with NaF alone (25 mg·(kg body mass)(-1)·day(-1)) or plus EGCG at different doses (20, 40, and 80 mg·(kg body mass)(-1)·day(-1)) for 4 weeks. Hepatotoxicity of NaF was determined by increased levels of serum hepatospecific markers and total bilirubin, along with increased levels of thiobarbituric acid reactive substances, lipid hydroperoxides, protein carbonyl content, and conjugated dienes. The hepatotoxic nature of NaF was further evidenced by the decreased activity of enzymatic and nonenzymatic antioxidant levels in liver. NaF-treated rats also showed increased DNA damage and fragmentation in hepatocytes. Administration of EGCG (40 mg·(kg body mass)(-1)) to NaF-intoxicated rats significantly recuperated the distorted biochemical indices, DNA damage, and pathological changes in the liver tissue. Thus, the results of the present study clearly demonstrate that EGCG has strong free radical scavenging, antioxidant, and antigenotoxic properties that protect against NaF-induced oxidative hepatic injury in rats.

Therapeutic itineraries of Congolese refugees in the city of São Paulo

ABSTRACTSão Paulo, the most populous Brazilian city, has been the main destination for refugees and it is home to the majority of Congolese, who are the second largest nationality to request refuge in Brazil. In the context of these migrations, previous experiences in displacement and in places of welcome can trigger illness and suffering. The purpose of this article was to analyse the therapeutic itineraries of refugees from the Democratic Republic of Congo who reside in the city of São Paulo. The research followed an ethnographic approach and included focus group, ethnographic observation and in-depth interviews with 15 Congolese men in refuge in São Paulo between 2015 and 2016. The difficulties faced in the dignified reconstruction of lives include housing, precarious work and racism. Different systems are actuated in healthcare, treatment in health centres and hospitals regarding acute and chronic physical problems, in addition to self-care, identified in the preparation of teas for gastrointestinal ailments. When confronted by suffering, religious social networks, and those of friends and family are activated, in addition to alcohol consumption. The family is sought when facing financial and, principally, emotional problems. The itineraries include multiple therapeutic systems and a dialectic relationship with free, universal services perceived as inequitable.

THE USAGE OF MAIN ROOM OF MIDDLE SCALE DAY CARE FACILITIES FOR THE ELDERLY

Covering at the middle scale day care facility for the elderly placed to special elderly nursing home that is expected to increase the role of fundamental facilities of large area, this paper aims at regulating the plan and corner arrangement pattern of main rooms, and explaining the feature of relation between room composition and usage. The room usage and construction method required of the main rooms of middle scale day care facilities are considered based on the acquired knowledge. The results are as follows. 1) Because table and chair are arranged in the center of the main room and free time, meal, and functional training are held in the same room in FTL+N type and FTL type corner arrangement cases, there are few selection options of user's sitting space. Since the functional training is held by putting away the table and chair and securing the large space, the clearing up and preparation of tea, etc. may be repeated so the cause of staff's work load and user's waiting time is the problem. The furniture for nap is not placed in FTL type, so the generous arrangement of table and chair, arrangement of sofa set or office corner etc. are available. 2) FL+FTN type corner arrangement cases divide the main rooms into two areas, and secure the place of meal and functional training in the constraints that the main room floor spaces are 74-109 square meters . By arranging sofas to the enclosure type and securing the space in the center of corner, users sit down on the sofa and meets at the time of functional training, and can hold gymnastics, game etc. in the FTN corner. At the time of a nap, it is also available to put down bedclothes on the floor of central part in addition to sofa, and to increase the number taking a nap. But there is a problem for keeping the quiet environmental at the time of functional training . Also in the facility with main room floor spaces of around 100square meters, FL+FTN type corner arrangement type is situated as the case that 2 area classification is materialized. 3) By the FL+FT+N type corner arrangement that divides the place of a meal and functional training into two areas, and also secures nap space in the main room independently, There can be many selection options of user's sitting space, in addition to the table and chair corner for meal, users can spend freely by sitting on the sofa or massage chair of relaxation corner. There are some scenes that staffs do preceded type preparation settlement work so the functional training corner serves as the place of waiting at lunch preparation time, staffs put away the table of functional training corner and prepare the recreation at the time of the snack in meal corner. According to the spatial and temporal separation of the staff work, the smooth management of the execution of daily program is attained with little waiting time. In this way, the point that the usage harnessed the feature of 2 area composition of the main rooms has realized is evaluated.

Genetic improvement of bougainvillea in Indian scenario - A review

Bougainvillea is a native of South America and it is a popular plant all over the world with tropical and warm climates. It is a thorny and woody plant having different coloured bracts viz., white, pink, purple, red, orange, yellow etc. Among the different species of Bougainvillea, Bougainvillea glabra and B. spectabilis are most popular across the world. Bougainvillea plants provide colour to the garden when the flowering of winter season annuals ceases and the blooming of summer annuals or other ornamental plants is yet to arrive. The ability of bougainvillea to grow under highly polluted conditions like traffic islands, roadsides and around industries has made it popular among the planners and architects. The plants can be grown as climbers by training them on walls of house or any building, parks, farms garden, open spaces and on arches or pergola or on a tree. The edible flowers of Bougainvillea are frequently used for the preparation of salads and flower teas in different parts of the world. The floral bracts are the rich source of betalain pigments particularly betacyanin which can be exploited as a natural colorant in food industries. Although, Bougainvillea has originated in South America, but approximately 50% of the present day cultivars were evolved and developed in India. The Division of Floriculture and Landscaping of IARI is a pioneering centre of Bougainvillea and have a good collection of germplasm of bougainvilleas. Besides, NBRI, Lucknow; IIHR, Bangalore; CAZRI, Jodhpur and BARC, Mumbai have contributed significantly in breeding of Bougainvillea. Division of Floriculture and Landscaping IARI, New Delhi has been recognized as the International Registration Authority for Bougainvilleas by Royal Horticultural Society, U.K, since, 1966 and again during the recent meeting of 2007 held at Wageningen, The Netherlands. The division is one of the major repository centre and more than 100 cultivars of Bougainvilleas are conserved here with different colour, thorny, thornless, variegated, bicoloured, multibracted etc. The varieties evolved at IARI include Dr. R.R. Pal, Stanza, Summer Time, Sonnet, Spring Festival and Vishakha.

Preparation and Properties of Functional Mulberry Leaf Tea by Salt-Vinegar Steaming-Fermentation

Functional mulberry leaf tea was obtained by salting-vinegar steaming-fermentation treatment. Water hardness,acetic acid content and 1-DNJ content were determined by EDTA titration,catalytic spectrophotometry and HPLC respectively. As the brine concentration was 2 g/L,water hardness of functional mulberry leaf tea was decreased from 1039.29 mg/mL to 310.14 mg/mL.The acetic acid content was reduced from 202.8 mg/kg to 139.4 mg/kg when the concentration of water in vinegar was 60 mL/L. After salting and vinegar-steaming,the mulberry leaf tea was fermented by koji at 12 h,the acetic acid content was further decreased to 43.52 mg/kg. The sensory score of mulberry leaf tea obtained by this method was 88.90 points. Compared with other mulberry leaf tea,the functional mulberry leaf tea had the most pleasant flavor and the lowest oxalic content with an acceptable content of the 1-DNJ and water hardness.

Mass spectrometry imaging of thin-layer chromatography plates using laser desorption/low-temperature plasma ionisation.

Thin-layer chromatography (TLC) is a classic method for the separation and analysis of complex mixtures. Biological assays, chemical derivatisation and spectroscopy techniques are compatible with TLC and provide extra information about isolated compounds. However, coupling TLC to mass spectrometry is hampered by the difficulty to desorb the analytes from the silica surfaces. In this study, we used a multimodal ion source for laser desorption (LD) and low-temperature plasma (LTP) post-ionisation. Efficient desorption was reached by covering the TLC plates with activated carbon. Regions of interest can be analysed by spots, by lines or by area. We show the separation of methylxanthines from coffee, tea and cocoa preparations by TLC, with subsequent mass spectrometry imaging (MSI). Using a lateral resolution of 400 μm × 400 μm, allowed the acquisition of 21 895 spectra in 2.4 h (2.5 pixels per s). Further, we demonstrate the possibility of direct mass fragmentation studies and quantification. We mounted the system on an Open LabBot with a theoretical lateral resolution of 12.5 μm and performed the visualisation of ions of interest and the pixel-wise review of mass spectra with our free software RmsiGUI (). This non-proprietary and modular platform enables the cost-efficient adaption of the system and further development by the community.

Applications of Tea (Camellia sinensis) and its Active Constituents in Cosmetics.

Studies on the cosmetic applications of plant extracts are increasingly appearing in the scientific literature, which is due to the growing popularity of skincare products around the world. In the light of the observed changes, a return to natural treatment and skincare with cosmetics free of harmful substances or toxic preservatives is visible. Currently, tea extracts, due to their rich composition and various biological actions, play an important role among the dietary supplements and cosmetics. This review is intended to collect the reports on the properties of the tea plant, its extracts and preparations in cosmetology: for skin care products and for the treatment of selected dermatological diseases. Particular attention is paid to its antioxidant, anti-hyaluronidase, anti-inflammatory, slimming, hair-strengthening, photoprotective and sealing blood vessels properties.

Contrasting allocation of magnesium, calcium and manganese in leaves of tea (Camellia sinensis (L.) Kuntze) plants may explain their different extraction efficiency into tea

During tea preparation mineral elements are extracted from the dried leaves of tea (Camellia sinensis (L.) Kuntze) plants into the solution. Micro-particle induced X-ray emission was employed to investigate the spatial distribution of magnesium (Mg), calcium (Ca) and manganese (Mn) in the young and old leaves of tea plants grown in the absence and presence of aluminium (Al) in the substrate. Results revealed that in tea leaves the largest concentrations of Mg occurred in the epidermis, of Ca in oxalate crystals and of Mn in epidermis and oxalate crystals; there was a leaf-age effect on tissue-specific concentrations of Mg, Ca and Mn with all tissues of old leaves containing larger concentrations of Mg, Ca and Mn than young leaves; supplementation of substrate with Al reduced concentrations of Mg, Ca and Mn in the old leaves, and a link between the distribution of Mg, Ca and Mn in the tea leaves with the extraction efficiencies of these elements into the tea was possible. We conclude that old leaves of tea plants cultivated under conditions of low Al availability will have the largest concentrations of Mg, Ca and Mn and may represent most acceptable ingredient for the preparation of tea.

The ramification of fermentation time on antioxidant properties of Napier grass herbal tea by black tea processing method

Tea fermentation relates to the enzymatic oxidation of the leaves of the tea and the formation of dark pigments. This method is usually conducted in a setting where temperature and humidity can be regulated. However, the impact of fermentation time on the antioxidant characteristics of Napier grass herbal tea is still unanswered. This study aimed to determine the effect of fermentation time on antioxidant properties of Napier grass black tea. Napier grass was subjected to fermentation for 3, 6, 9, 12 and 24 hrs. Fresh and dried samples were extracted in water (95°C, 30 mins) and the extracts were then analysed by total phenolic content (TPC) assay, total flavonoid content (TFC) assay, diphenyl-picryl-hydrazyl (DPPH) assay, Ferric reducing antioxidant potential (FRAP) assay, ferric thiocyanate (FTC) method and thiobarbituric acid (TBA) method. Sample fermented for 9 hrs showed the highest results in TPC (18.32±0.38) and FRAP assay (91.00±2.78). Whereas, the highest flavonoids and antioxidant activity were found in dried sample without fermentation (control) in TFC (97.82±13.00) and DPPH (90.02±1.11). However, samples fermented for 3 to 9 hrs showed no significant difference with that of the fresh sample in TFC and DPPH indicating 3 to 9 hrs fermentation time did not affect the antioxidant properties of Napier grass. In FTC and TBA, all the fermented samples showed lower antioxidant activity than that of fresh samples and control. The results suggested that 9 h of fermentation time is suitable for the preparation of Napier grass black tea as it exhibited high antioxidant properties in TPC, TFC, DPPH and FRAP assays.

Preparation, antibacterial and antioxidant properties of green tea seed oil nanoemulsions by self‐emulsification method

Application of tea oil in food products has been gained more and more attention for its nutritional advantages and functional properties. This research fabricated green tea seed oil nanoemulsions by the self-emulsification method through variation of oil and surfactant composition. Finally, in vitro antibacterial assay and antioxidant properties were investigated. The results showed that the sizes could be regulated through surfactant content (5–15 wt%) and composition (HLB 10.72–13.93) from 16.44 ± 0.01 nm to 329 ± 4.74 nm. With the increase of the content of green tea seed oil, the DPPH and total antioxidant capacity of the nanoemulsions were gradually improved. Meanwhile, the antibacterial assay was enhanced as the content of green tea seed oil increased from 0.5 to 1.5%. The inhibition zone increased continually to 7.56 ± 0.40 mm and 6.85 ± 0.59 mm when 1.5% oil was provided. The results could provide a reference to essential oils in the design of functional food-grade ingredients.