Prevention of the deterioration of polyphenol-rich beverages

Only a small amount of H₂O₂ was detected in beverages, such as tea or coffee, immediately after opening caps of bottles, but H₂O₂ was gradually produced in the beverages after opening the caps, i.e. exposure to air. The beverages with high concentrations of polyphenols showed high 1,1-diphenyl-2-picrylhydrazyl (DPPH) radical-scavenging activities, but produced relatively high concentrations of H₂O₂ when they were exposed to air, possibly due to oxygen. The production of H₂O₂ increased both with duration of the exposure to air and rise in temperature. Since H₂O₂ is toxic, ways to prevent the deterioration of catechin-enriched green tea, i.e. H₂O₂ production, were studied. The addition of catalase, which is an enzyme decomposing H₂O₂, reduced the H₂O₂ concentration, but it was inactivated at a high temperature. The addition of l-cysteine or glutathione (reduced form), with a thiol residue, reduced the H₂O₂ concentration. Addition of citric acid, malic acid, succinic acid, fumaric acid, l-ascorbic acid, l-glutamic acid and l-aspartic acid also reduced it, possibly because they lower the pH of the tea.     

Antioxidative and anti-hydrogen peroxide activities of various herbal teas

Herbal teas, i.e., extracts of herbs, are popular because of their fragrance and antioxidative activity. Since the antioxidative activity comes mainly from polyphenols, total polyphenol concentrations and 1,1-diphenyl-2-picrylhydrazyl (DPPH) radical-scavenging activities in herbal teas were measured and compared. Levels of H₂O₂ in the teas were also examined, since the production of H₂O₂ in beverages such as coffee and green tea, has been reported. Only a small amount of H₂O₂ was detected in the herbal teas just after their preparation with hot water. However, H₂O₂ was gradually produced during incubation at 25 °C after extraction with hot water, especially when the teas were incubated in phosphate buffer at pH 7.4. To examine the anti-H₂O₂ activity of herbal teas, various teas were added to a catechin-enriched green tea, which produce much H₂O₂, and they were incubated at 25 °C for one day. Addition of hibiscus and thorn apple tea decreased the production of H₂O₂ in the catechin-enriched green tea, possibly because of a lowering of the pH of the mixture.     

Protective effects of the crude extracts from yam (Dioscorea alata) peel on tert-butylhydroperoxide-induced oxidative stress in mouse liver cells

Researchers have shown that yam extracts contain antioxidative activity; however, there are few reports regarding the antioxidant activities of yam peel. The effects of water and 50% ethanolic extracts from Darsan yam (Dioscorea alata) peel on the oxidative status of tert-butylhydroperoxide (t-BHP)-treated mouse Hepa 1–6 and FL83B liver cell lines were investigated. The cytosols were analysed for H₂O₂ and malondialdehyde (MDA) levels and antioxidative enzymes activities, including superoxide dismutase, glutathione peroxidase (GPx) and catalase activities. Both water and 50% ethanolic extracts from yam peel did not affect cellular MDA level in t-BHP-treated cells, but they altered the level of H₂O₂. Water extract from yam peel amplified the t-BHP-induced cytotoxicity in Hepa 1–6 whilst the ethanolic extract showed protection in FL83B cells. GPx activity might play an important role in the protective effect associated with t-BHP-induced oxidative stress.     

Amperometric determination of hydrogen peroxide residue in beverages using a Nafion modified palladium electrode

Hydrogen peroxide (H₂O₂) residues are not permitted in food due to health concerns. An amperometric sensor based on a Nafion modified palladium (Pd) electrode was developed for the rapid determination of the H₂O₂ residue in aseptically packaged beverages. A prepared Pd electrode shows a slowly increasing reaction upon repeating the procedure of adding the same concentration of H₂O₂ into the reaction cell unless pretreating the electrode with cyclic voltammetry to obtain reproducible surfaces, whereas a Nafion modified Pd electrode can reach stable reaction to H₂O₂ without any pretreatment. The interference level of ascorbic acid (the ration of electrochemical response to ascorbic acid to the electrochemical response of H₂O₂) was calculated as 0.0004 for the Nafion modified Pd electrode. Interference (99.5%)from ascorbic acid was diminished by Nafion membrane. The response of the sensor to H₂O₂ in distilled water is linear over the range of 0.25–15 μM (r ² = 0.9956). The sensor developed in this study can efficiently determine H₂O₂ residues in commercial beverages with good linear correlation between spiked H₂O₂ concentration and detected H₂O₂ concentration, for winter melon-flavored drink, r ² = 0.9904 in the range of 0.25–15 μM and for lemon-flavored tea, r ² = 0.9927 in the range of 0.25–25 μM.     

绿茶、橘皮、大豆中酚类物质体外消化前后稳定性及抗氧化活性的研究

本研究以富含3类代表性酚类化合物（黄烷醇、黄烷酮和异黄酮）的3种食物（绿茶、橘皮、大豆）作为原料,模拟其在人体口胃肠中的体外消化过程。采用高效液相色谱-二极管阵列检测器/电喷雾-四极杆-飞行时间串联质谱检测器（HPLC-DAD/ESI-Q-TOF-MS）检测体外消化前后酚类化合物的种类及含量变化,同时测定不同消化阶段总酚含量（TPC）、总黄酮含量（TFC）以及抗氧化活性（DPPH、ABTS、FRAP、ORAC）的变化。结果表明,绿茶提取物中检测出4种酚类化合物（表没食子儿茶素、(+)-儿茶素、表没食子儿茶素没食子酸酯和表儿茶素没食子酸酯）,大豆提取物中检测出4种酚类化合物（大豆苷、染料木苷、大豆苷元和染料木素）,橘皮提取物中检测出2种酚类化合物（柚皮苷和橙皮苷）;三种食物提取物中,经过体外消化后,绿茶提取物中的酚类化合物最不稳定,除(+)-儿茶素外,其余3种酚类物质几乎降解完全,损失率均达95%以上。绿茶、橘皮、大豆提取物的TPC在胃消化阶段显著升高（P<0.05）,在肠消化阶段显著降低（P<0.05）。绿茶提取物TFC在口腔和胃消化阶段显著升高（P<0.05）,在肠消化阶段显著降低（P<0.05）。橘皮、大豆提取物TFC与TPC变化趋势一致。绿茶提取物的四种抗氧化活性经胃肠消化后呈先升高再降低的趋势。大豆提取液体外消化前后ABTS、FRAP抗氧化活性在口腔阶段显著降低（P<0.05）,DPPH、ORAC抗氧化活性在口腔、胃消化阶段显著升高（P<0.05）,在肠消化阶段显著降低（P<0.05）。橘皮提取液ORAC抗氧化活性在肠消化阶段显著升高（P<0.05）,ABTS、FRAP抗氧化活性在体外消化阶段均表现出和总酚含量变化一致的趋势。     

Anti-hydrogen peroxide activity of fish and soy sauce

Shoyu is the Japanese name for soy sauce and the most popular liquid condiment (seasoning) used in Japanese cuisine as well as in cuisines of other oriental countries. Shoyu is prepared by digesting mold-cultured soybeans and wheat seeded with an aspergillus (koji in Japanese) in the presence of sodium chloride. Gyoshoyu is produced when the soybeans and wheat are replaced with fish. Both Shoyu and Gyoshoyu have high level of 1,1-diphenyl-2-picrylhydrazyl (DPPH) radical-scavenging activity. Hydrogen peroxide is produced in green tea after exposure to air. To find a safe and economical method of preventing the production of H₂O₂ in green tea, effects of Shoyu and Gyoshoyu on H₂O₂ level in bottled green tea were examined. Both Shoyu and Gyoshoyu suppressed the production of H₂O₂. Gyoshoyu decomposed H₂O₂ possibly because of the presence of a thermostable catalase, while Shoyu did not. Some components of Shoyu and Gyoshoyu may be useful to suppress the production of H₂O₂ in green tea.     

In vitro antioxidant and anticancer activities of ethanolic extract of selenium-enriched green tea

Selenium-enriched green tea is now being increasingly produced in China and is well known as a bioactive beverage, due to its high content of active components. In this study, the antioxidant and anticancer activities of an ethanolic extract and an aqueous extract of Se-enriched green tea were investigated. The results indicated that the ethanolic extract possessed significantly higher antioxidant activity than the aqueous extract and the positive control α-tocopherol, by both α,α-diphenyl-β-picrylhydrazyl (DPPH) radical-scavenging and ferric thiocyanate (FTC) assays. The ethanolic extract inhibited the proliferation of human cervical adenocarcinoma HeLa cell and possessed a significantly higher antitumour activity than the aqueous extract and the positive control 5-fluorouracil (5-FU), in the dose range of 62.5–250 μg/ml. Moreover, the ethanolic extract could significantly inhibit the growth of lung carcinoma A549 and hepatoma HepG2 in a concentration-dependent manner, with IC₅₀ values of 278.6 μg/ml and 431.6 μg/ml, respectively. Selenium, tea polyphenols and polyphenols constituents, especially epigallocatechin gallate (EGCG), were significantly higher in the ethanolic extract than in the aqueous extract, which were possibly responsible for the higher antioxidant and antitumour activities of the ethanolic extract.     

Antioxidant and antiproliferative activities of mango (Mangifera indica L.) flesh and peel

The antioxidant and antiproliferative properties of flesh and peel of mango (Mangifera indica L.) were investigated. The cytoprotective effect of mango flesh and peel extracts on oxidative damage induced by H₂O₂ in a human hepatoma cell line, HepG2, were determined, and the underlying mechanism was examined by a single-cell electrophoresis assay (comet assay). Treatment of HepG2 cell with mango peel extract prior to oxidative stress was found to inhibit DNA damage. The free radical scavenging activities of mango flesh and peel extracts were evaluated by electron spin resonance (ESR). The mango peel extract exhibited stronger free radical scavenging ability on 1,1-diphenyl-2-picrylhydrazyl (DPPH) and alkyl radicals than mango flesh extract, regardless of ripeness. Similarly, peel extract exhibited significant antiproliferative effect against all tested cancer cell lines, compared to that of flesh extract, in a dose-dependent manner. The result also showed that the antiproliferative activity of mango flesh and peel extracts correlated with their phenolic and flavonoid contents. Thus, mango peel, a major by-product obtained during the processing of mango product, exhibited good antioxidant activity and may serve as a potential source of phenolics with anticancer activity.     

Recycling of industrial essential oil waste: Brutieridin and Melitidin, two anticholesterolaemic active principles from bergamot albedo

Bergamot albedo, the white tissues between the skin and the pulp, is a polluting waste in the production of the renowned fragrance and is easily available by simple industrial processes. Brutieridin and melitidin are found in bergamot albedo and possess statin-like activity. Their anticholesterolaemic effect has been proved in vitro. Different procedures were exploited to assay the presence of brutieridin and melitidin and to evaluate their availability in water extracts. The best results in terms of simplicity and accessibility of the method were obtained with hot water at 65 °C. Interestingly, tea beverages enriched with the two active principles have been obtained by simple addition of dried albedo into commercial tea bags. This is the first report on the availability of methodologies to extract active principles from citrus albedo wastes.     

天然高香液体茶的加工技术

普通液体茶的香气由于加工过程中大量挥发散失 ,从而普遍存在香气淡薄的缺陷 ,必须进行人工调香 ,而原料茶萃取后的茶渣中却富含大量的键合态茶叶香气。文中通过酸水解方法释放茶渣中的键合态香气 ,释放出的挥发物经蒸馏回收后 ,重新添加进液体茶中 ,从而明显改善液体茶香气品质。该方法成本低、无有害残留 ,操作简单 ,适于工业化生产。     

Citrus peel extract – A natural source of antioxidant

Citrus peel extract as a natural source of antioxidant was evaluated during 6 months storage of refined corn oil at 25 and 45 °C. Extracts of citrus peel were prepared by refluxing the dried ground peel with ethanol, methanol, acetone, hexane, diethyl ether and dichloromethane. Maximum amount of citrus peel extract was obtained with methanol. Antioxidant activity of methanolic extract was assessed by measuring free fatty acid (FFA) content peroxide value (POV) and iodine value (IV) during 6 months storage of refined corn oil at 25 and 45 °C. After 6 months of storage at 45 °C, corn oil containing 1600 and 2000 ppm citrus peel extract, showed lower FFA contents (1.5% and 1.0%), and POVs (8.38 and 7.0 meq kg⁻¹) and higher iodine values (81, 89) than the control sample (FFA 17.0% POV 101 meq kg⁻¹ IV 47). Refined corn oil containing 200 ppm of butylated hydroxy anisole (BHA) and butylated hydroxy toluene (BHT) showed FFA contents of 2.0% and 1.8%, POVs 17.0 and 12.7 meq kg⁻¹ and IVs 84 and 87, respectively, after 6 months of storage at 45 °C. These results show that methanolic extract of citrus exhibited very strong antioxidant activity, which was almost equal to synthetic antioxidants (BHA and BHA). Therefore, the use of citrus peel extract is recommended as a natural antioxidant to suppress development of rancidity in oils and fats.     

Shelf life extension of ground chicken meat using an oxygen absorber and a citrus extract

In the present study the combined effect of an O₂ absorber and a citrus extract (0.1 and 0.2 ml/100 g), on shelf life extension of fresh ground chicken stored at 4 °C was investigated. Microbiological changes [Total viable count (TVC), Pseudomonads, Lactic acid bacteria (LAB), Enterobacteriaceae, and Clostridium spp.)], physicochemical changes (pH, total volatile nitrogen (TVB-N), and colour) and sensory changes (colour, odour and taste) were monitored as a function of treatment and storage time (14 days). Aerobically packaged ground chicken meat stored at 4 °C was taken as the control sample. On day 6 of storage TVC was reduced by 0.5, 1.0 and 1.5 log cfu/g by the citrus extract (0.2 ml/100 g), the O₂ absorber and the combination of the O₂ absorber plus citrus extract (0.2 ml/100 g), respectively (p < 0.05). Initial pH (6.38) showed an increase (6.73) or decrease (5.83) depending on specific treatment. TVB-N ranged between 42.5 and 57.5 mg/kg at the time of sensory rejection. Colour parameters remained unaffected in samples containing the O₂ absorber and/or citrus extract. A 4–5 days product shelf life extension using the combination of O₂ absorber and citrus extract (0.1 ml/100 g) as compared to control samples was achieved.     

Jaboticaba (Plinia trunciflora (O. Berg) Kausel) fruit reduces oxidative stress in human fibroblasts cells (MRC-5)

Jaboticaba species (Plinia sp.) have attracted attention because of their significant levels of phenolic compounds, primarily anthocyanins and flavonols. Jaboticaba, termed the Brazilian berry, has emerged as a new functional food with potential health benefits. Plinia trunciflora (O. Berg) Kausel is one of the main species of jaboticaba that is naturally occurring and cultivated in Brazil. Thus, this study aimed to determine the macronutrient and phenolic compositions of P. trunciflora pulp and peel. Additionally, jaboticaba peel extract (JPE) was evaluated for its in vitro antioxidant activity and its capacity to modulate oxidative stress as well as mitochondrial function in human lung fibroblast cells (MRC-5). The macronutrient found to have the highest level in both the peel and pulp was carbohydrates, followed by the high fiber content of the peel. The total phenolic compounds and anthocyanin levels were higher in the peel than in the pulp. High resolution mass spectrometry (HRMS) showed the presence of cyanidin-3-O-glucoside and kaempferol. Moreover, JPE was able to reduce the decreases in complex I activity and the ATP levels induced by H₂O₂ and thereby decreased the oxidative stress in MRC-5 cells. These findings show a new role for jaboticaba as a mitochondrial protectant in pathological conditions where mitochondrial dysfunction is involved.     

The influence of oxidizing agents on water extracts of rye flour

The main constituents of rye flour extracts are proteins and pentosans. After cross-linking under the action of oxidizing agents those components are able to bind much more water than in their native (prior to modifications) state. As a consequence rheological properties of extract are changed.It was observed that kinematic viscosity of water extract of rye flour decreases rapidly with time. The reason for this behavior could be high enzymatic activity of flour extract.It was also found that the addition of hydrogen peroxide in the absence of additional peroxidase (which is naturally present in 1:9 or 1:1 water extracts of flour) causes the greatest increase in viscosity, due to the cross-linking of soluble polymers. Moreover after the addition of H₂O₂ to water extracts strong gels were obtained, which were characterized by tan δ = 0.5 (tan δ < 1). Moreover G′ was independent of frequency, which also suggests cross-linking of the pentosans.The addition of ascorbic acid, which is known to act preferably on gluten proteins, to 1:9 or 1:1 flour extracts had only a little effect on viscosity. In this case the values of tan δ = 0.9 were close to 1, which is typical for a weak gel.The application of inactivated rye flour extract, containing mainly proteins and pentosans, proved stronger effect of H₂O₂ in comparison to ascorbic acid on polymer cross-linking, but only after the addition of peroxidase. The gel obtained with H₂O₂ and peroxidase was also characterized by low tan δ = 0.4.The results indicate, that pentosans are the main subject of cross-linking reactions in rye flour water extracts.     

Cytoprotective effect of white tea against H2O2-induced oxidative stress in vitro

The protective effect of water extracts of white tea (WEWT) on oxidative stress in vitro is investigated. WEWT, like water extracts of green tea (WEGT) and water extracts of Pu-erh tea (WEPT), demonstrates a marked inhibition of the oxidation of liposome, albumin and LDLmodel systems. WEWT protects against H₂O₂-induced cytotoxicity, in a dose-dependent manner. The inhibition of ROS generation and MDA formation by WEWT in H₂O₂-induced Clone 9 cells parallels the effects on cell viability. Moreover, GSH and antioxidant enzymes may play an important role in the protective effect that is associated with H₂O₂-induced oxidative stress. The HPLC-DAD and HPLC–MS/MS analysis, shows that sixteen bioactive compounds are present in WEWT, which may partially account for its protective effect against oxidative insult. These results suggest that the mechanism of the protective actions of WEWT is related to its antioxidant potential and the maintenance of the normal redox status of the cell.     

Characteristics and upregulation of antioxidant enzymes of kitchen mint and oolong tea kombucha beverages

Kombucha is a healthy traditional beverage which is made by fermenting products with a symbiotic culture of acetic acid bacteria and yeasts. In present study, leaves of kitchen mint (Mentha cordifolia Opiz. Ex Fresen) and leaves of oolong tea (Camellia sinensis) were fermented in kombucha formula. After fermentation, titratable acidity contents and ethanol of kitchen mint, oolong tea, and mixtures of oolong tea and kitchen mint kombucha samples gradually increased with a period of fermentation time. At day 14 of fermentation, phenolic compounds and flavonoids were increased in all kombucha samples. The numbers of acetic acid bacteria and yeast in kombucha had gradually raised during 7–14 days of fermentation. DPPH and ABTS scavenging activities of these kombucha increased over a period of fermentation time and shown the highest antioxidant capacity on day 14 of fermentation. In addition, all kombucha samples exhibited the antioxidant effects by attenuating H₂O₂-induced ROS production, increasing mRNA expression of catalase, glutathione reductase (GRe), and Mn-SOD, and inducing GRe enzymatic activity in HEK-293 cells. Kombucha beverage can be used as the healthy beverages for attenuation of oxidative stress in many diseases.     

An amperometric sensor based on Prussian blue and poly(o-phenylenediamine) modified glassy carbon electrode for the determination of hydrogen peroxide in beverages

An amperometric sensor based on Prussian blue (PB) and poly(o-phenylenediamine) (POPD) modified glassy carbon electrode (GCE) was developed for the determination of hydrogen peroxide (H₂O₂). The PB film was electrodeposited onto the GCE surface by amperometry, while the POPD film was formed on the top of PB layer by cyclic voltammetry. It was found that the POPD film remarkably improved the stability and selectivity of PB-based sensor. Under the optimised conditions, the developed electrode demonstrated a wide linear range from 0.1 μM to 0.12 mM with the detection limit of 0.05 μM. Furthermore, the developed electrode was applied for the amperometric determination of H₂O₂ in 10 different commercial beverages. The pretreatment of the beverage samples was the adjustment of pH value. Experimental results showed that the proposed electrode could be a useful tool to detect H₂O₂ in aseptically packaged beverages.     

Hydrogen peroxide concentration measured in cultivation substrates during growth and fruiting of the mushrooms Agaricus bisporus and Pleurotus spp.

Hydrogen peroxide is suspected of being highly implicated in mushroom nutrition and in substrate bleaching during cultivation. The parameters for measuring H₂O₂ in compost samples were examined and the methodology was applied to samples from both compost colonized by cultivars and wild isolates of Agaricus bisporus, and wheat straw or coffee pulp colonized by Pleurotus spp. Laccase and peroxidase activities were also measured. H₂O₂ concentration measured after heating at 80 °C for inactivating laccases and peroxidases was probably both H₂O₂ pre‐existing in the compost and H₂O₂ generated from quinones and active oxygen species. This potential H₂O₂ concentration increased during the vegetative growth for all the strains, in agreement with a direct relationship between H₂O₂ concentration and active biomass of A. bisporus or Pleurotus spp. in their cultivation substrates. Correlations were observed between H₂O₂ concentration and manganese peroxidase activity in cultivation substrates at the stage of primordia formation. At this stage of development, H₂O₂ generation via biotic or abiotic mechanisms should be an important physiological trait of mushrooms. Copyright © 2007 Society of Chemical Industry     

Polymethoxy flavones are responsible for the anti-inflammatory activity of citrus fruit peel

In traditional Chinese medicine, dried citrus fruit peels are widely used as remedies to alleviate some respiratory inflammatory syndromes and are considered as potential sources of anti-inflammatory components. Seven citrus fruits were selected for this study. We determined the inhibitory ability of citrus peel extracts on the production of pro-inflammatory mediators, prostaglandin E₂ (PGE₂) and nitric oxide (NO), in lipopolysaccharide (LPS)-activated RAW 264.7 cells. Among the tested citrus peels, Ponkan (Citrus reticulata Blanco) and Tonkan (Citrus tankan Hayata) deserve special attention due to their outstanding inhibitory effect on PGE₂ and NO secretion. We have also examined the composition, flavanone glycosides and polymethoxy flavones. The polymethoxy flavone content, especially nobiletin, appears to correlate well with the anti-inflammatory activities of certain citrus peel extracts. Thus, our results suggest that polymethoxy flavones contribute crucially to the anti-inflammatory activity of citrus peels.     

Phenolic compounds and the biological effects of Pu-erh teas with long-term storage

Pu-erh tea has gained more and more popularity and attracted much attention for its various biological effects. The objective of this study was to determine the active phenolic compounds and the biological effects of 15 differently aged Pu-erh teas. The results showed that 43 active phenolics, containing 7 flavan-3-ols, 11 organic acids, and esters, 3 proanthocyanidin dimers, 2 benzotropolones, and 20 flavonoid glycosides were identified based on high-performance liquid chromatography coupled to electrospray ionisation and quadrupole time-of-flight tandem mass spectrometry (HPLC-ESI-QTOF-MS/MS). In particular, 2’-O-galloylhyperin and quercetin-3-O-p-coumaroyl-rhamnosyl-arabinosyl-hexoside were identified from constituents of tea for the first time. The 15 Pu-erh teas exhibited strong DPPH and ABTS scavenging activity in a concentration-dependent manner with IC₅₀ 0.99–2.12 and 0.97–2.67 mmol Trolox equivalent antioxidant capacity/g, respectively. All of the Pu-erh teas tested significantly inhibited the proliferation of SMMC-7721 cells, in a dosage-dependent manner. Of the 15 Pu-erh teas examined, the cake tea P6 had the strongest effect on SMMC-7721 cells with IC₅₀ = 65.88 ± 3.53 µg/mL. The others Pu-erh teas had an IC₅₀ = 96 – 509 µg/mL. Our results also indicated that not all the older Pu-erh teas display stronger anti-activities and anti-cancer than the younger ones and the youngest Pu-erh tea did not possess the highest level of active components. This study provides useful information for consumers to deeply understand the chemical constituents and bioactivity of Pu-erh tea preserved for a long time.