Fermentation of tea in aqueous suspension

The fermentation of macerated tea leaf in aqueous suspension has been studied both manometrically and in a suitably controlled fermentation vessel. Oxygen consumption proceeded rapidly at a steady rate for an initial period, termed the primary fermentation, then decreased sharply as the availability of simple polyphenol substrates became rate limiting. Maximum reaction rates were observed at 20-35 mg ml^?1 total solids, as a result of substrate inhibition. At higher concentrations of solids reaction rates were also affected by diffusion effects within the leaf particles. At 50 mg ml^?1 total solids and 25°C the system approximated to Michaelis-Menton kinetics with K_m⁰² = 5 × 10^?5M and V_max corresponding to a primary fermentation time (PFT) of 10-15 min. The PFT corresponded with the attainment of maximum total colour and maximum level of theaflavins (TF) (often >30% of total colour). Beyond the PFT total colour remained constant, TFs decreased and non-dialysable pigments increased with time. At fixed levels of dissolved oxygen and solids concentration > 60 mg ml^?1 the proportion of TFs was inversely related to solids concentration. At 50 mg ml^?1 total solids TFs increased to ca 60% of total colour as the dissolved oxygen level was increased to 0.175 mM. As temperature was increased from 15-35°C the reaction rate increased, the proportion of TFs decreased slightly and thearubigins of intermediate molecular weight increased markedly.     

信阳红茶发酵工艺研究

以信阳毛尖为原料,采用加入优势菌群的微生物渥堆发酵.初步研究了信阳红茶发酵的基本条件,并对其发酵工艺进行了优化.以温度、时间、水分、菌种用量4个因素设计正交试验,最终以感官评价和茶多酚含量的变化来判断茶叶发酵的好坏.结果表明,茶叶在温度50℃,水分40％,菌种用量15mL/500g干茶叶,发酵时间18d时效果较好.     

Effect of rare earth elements on peroxidase activity in tea shoots

Rare earth microelement fertiliser (REMF) can increase the yield and quality of crops and has been widely applied in Chinese agriculture. However, relatively little is known about the physiological effects of rare earth ions. In this study the effects of REMF on the biomass and peroxidase (POD) activity of tea plants were investigated. The possible inductive mechanism of POD was also analysed. The results showed that REMF could promote POD activity in tea shoots and enhance the tea shoot biomass. The POD protein in tea shoots was found to bind rare earth elements, mainly La, Nd and Ce. It was also proved that La³⁺ and Nd³⁺ increased POD activity in vitro. The POD activity induced by La³⁺ and Nd³⁺ is possibly related to partial replacement of the metals in POD by La³⁺ and Nd³⁺. Copyright © 2003 Society of Chemical Industry     

Human disposition of L-theanine in tea or aqueous solution

After consumption of tea, L-theanine enters systemic circulation and is assumed to enter the brain. Several human studies indicate that L-theanine influences brain functioning. Knowledge about the pharmacokinetics of L-theanine facilitates further study of this health effect. Volunteers received 25–100 mg of L-theanine as tea, as L-theanine-enriched tea, and as biosynthetic L-theanine in aqueous solutions. Plasma was analysed for L-theanine content after which data were fitted with a 1- compartment model. For all interventions, the lag time was approximately 10 min and half-lives of absorption and elimination were approximately 15 and 65 min respectively. After approximately 50 min, maximum plasma concentrations of between 1.0 and 4.4 mg/L were achieved. Maximum plasma concentration and area under the plasma-concentration–time curve were dose-proportional. This knowledge allows prediction of plasma concentrations for various dose regimens supporting further study of a health benefit of L-theanine.     

Short communication: Influence of an aqueous myrrh suspension on yogurt culture bacteria over yogurt shelf life

Myrrh is an essential oil and natural flavoring approved by the US Food and Drug Administration, and it has antibacterial and antifungal activity against pathogens. Our objective was to determine the effect of an aqueous myrrh suspension on Streptococcus thermophilus and Lactobacillus delbrueckii ssp. bulgaricus counts in peptone solution and yogurt, as well as pH and titratable acidity of yogurt during 5 wk of storage at 1 to 4°C. The myrrh suspension (10% wt/vol) was prepared and incorporated into a pure culture dilution in peptone and into yogurt mix at a 1% (vol/vol) level. A control with no myrrh was also prepared, and 3 replications were conducted. Streptococcus thermophilus were enumerated using Streptococcus thermophilus agar with aerobic incubation at 37°C for 24 h, and Lactobacillus delbrueckii ssp. bulgaricus were enumerated using de Man, Rogosa, and Sharpe agar adjusted to pH 5.2, with anaerobic incubation at 43°C for 72 h. During the 8-h period after inoculation, S. thermophilus and L. delbrueckii ssp. bulgaricus counts in peptone solution at 37°C and 43°C, respectively, were not significantly different in the presence or absence of the aqueous myrrh suspension. Counts of S. thermophilus in yogurt containing myrrh (mean ± SD; 4.96 ± 0.58 log cfu/mL) were not significantly different from those in the control yogurt (4.87 ± 0.39 log cfu/mL). The log counts for L. delbrueckii ssp. bulgaricus in yogurt containing myrrh (5.04 ± 1.44 log cfu/mL) and those of the control (5.52 ± 1.81 log cfu/mL) did not differ, and the counts remained within 1 log of each other throughout 5 wk of storage. The pH of the yogurts containing the aqueous myrrh suspension was not significantly different from that of the control yogurts, and their pH values were within 0.1 pH unit of each other in any given week. Titratable acidity values remained steady around 1.1 to 1.2% lactic acid for both yogurt types throughout the storage period, with no significant differences between them. Yogurt culture bacteria can survive in the presence of a myrrh suspension in yogurt with no significant change in pH or titratable acidity. Therefore, it may be beneficial to add an aqueous myrrh suspension to yogurt.     

Photocatalytic degradation and mineralization of commercial methamidophos in aqueous titania suspension

The photocatalytic degradation of a commercial methamidophos (MAP) emulsion in aqueous suspension containing mesoporous titania (m-TiO2) nanoparticles under UV irradiation was investigated. The mineralization rate of MAP went up steadily as prolonging the irradiation time and reached ca. 95% after 4 h irradiation based on determination of the end-products (NO3-, PO4(3-), and SO4(2-)) of MAP through IC analysis. Moreover, the degradation kinetics of MAP followed the first-order reaction and has been monitored through GC-PFPD analysis, which also showed that MAP and the organic solvent as well as additive in the pesticide emulsion can be degraded readily and simultaneously. Photodegradation intermediates derived from two different concentrations of MAP were detected by GC-MS technique. The experimental facts indicated that the photodegradation mechanism of MAP mainly involves electron transfer process and hydroxylation process, and the dominant mechanism for MAP degradation in the initial steps can be attributed to the electron transfer process, which resulted in the formation of all intermediates containing P species detected in the initial photodegradation stage.     

超声波辅助水剂法提取茶叶籽油工艺的研究

研究了超声波辅助水剂法提取茶叶籽油工艺中原料粉碎度、兑浆水pH、液料比、浸提温度、浸提时间和超声时间对油脂提取率的影响.获得的最佳工艺条件为:原料粉碎度60～80目,兑浆水pH 6,液料比4:1,浸提温度70℃,浸提时间4 h,超声时间30 min.在最佳工艺条件下,油脂提取率为70.79%,副产品淀粉提取率为56.13%.     

微波辅助双水相提取绿茶中茶多酚的研究

采用微波辅助乙醇-磷酸氢二钾双水相体系提取绿茶中的茶多酚,对乙醇体积分数、磷酸氢二钾用量、提取时间、液料比和微波功率等影响因素作了详细研究与优化。实验结果表明,最佳工艺条件为:乙醇体积分数50%,磷酸氢二钾用量7.0 g,液料比50 m L·g^-1,微波功率370 W,提取时间30 s,在此条件下,茶多酚得率可达38.98%。研究结果可应用于绿茶中茶多酚的提取和绿茶品质分析。      

Spectroscopic study of carbaryl sorption on smectite from aqueous suspension

Sorption of carbaryl (1-naphthyl-N-methyl-carbamate) from aqueous suspension to smectite was studied using Fourier transform infrared (FTIR), high-performance liquid chromatography (HPLC) (for batch sorption), and quantum chemical methods. The amount of carbaryl sorbed was strongly dependent on the surface-charge density of the smectite with more sorption occurring on the two "low" surface-charge density smectites (SHCa-1 and SWy-2) compared to that of the high surface-charge SAz-1 smectite. In addition, the amount of carbaryl sorbed was strongly dependent on the nature of the exchangeable cation and followed the order of Ba approximately Cs approximately Ca > Mg approximately K > Na approximately Li for SWy-2. A similartrend was found for hectorite (SHCa-1) of Cs > Ba > Ca > K approximately Mg > Na approximately Li. Using the shift of the carbonyl stretching band as an indicator of the strength of interaction between carbaryl and the exchangeable cation, the observed order was Mg > Ca > Ba approximately K > Na > Cs. The position of the carbonyl stretching band shifted to lower wavenumbers with increasing ionic potential of the exchangeable cation. Density functional theory predicted a cation-induced lengthening of the C=O bond, resulting from the carbonyl group interacting directly with the exchangeable cation in support of the spectroscopic observations. Further evidence was provided by a concomitant shift in the opposite direction by several vibrational bands in the 1355-1375 cm(-1) region assigned to stretching bands of the carbamate N-Ccarbonyl and Oether-Ccarbonyl bonds. These data indicate that carbaryl sorption is due, in part, to site-specific interactions between the carbamate functional group and exchangeable cations, as evidenced by the FTIR data. However, these data suggest that hydrophobic interactions also contribute to the overall amount of carbaryl sorbed. For example, the FTIR data indicated thatthe weakest interaction occurred when Cs+ was the exchangeable cation. In contrast, the highest amount of carbaryl sorption was observed on Cs-exchanged smectite. Of all the cations studied, Cs has the lowest enthalpy of hydration. It is suggested that this low hydration energy provides the carbaryl with greater access to the hydrophobic regions of the siloxane surface.     

绿茶色素用于涤纶织物的染色

研究绿茶萃取液用于涤纶织物的染色,试验染液的PH值和浓度、媒染剂类型以及染色温度和压力对涤纶织物染色深度和水洗牢度的影响。结果显示采用硫酸亚铁和氯化亚锡作为媒染剂,利用绿茶色素对涤纶织物进行染色,可以得到一系列的棕色,水洗牢度可达4级以上。     

Mechanism and pathways of chlorfenapyr photocatalytic degradation in aqueous suspension of TiO2

The light-induced degradation of chlorfenapyr under UV was investigated in aqueous solutions containing TiO2 as photocatalyst. The photocatalytic degradation of chlorfenapyr followed pseudo-first-order degradation kinetics (Ct = C0e(-kt)). The study focused on the identification of possible intermediate products during the degradation, using gas chromatography mass-spectrometry (GC-MS) and 1HNMR. Six aromatic intermediates were identified by several techniques during the treatment and some of them were further confirmed by matching authentic standards. Structure analysis of the degradation products suggested two degradation pathways: (1) The aliphatic ether group was cleaved from chlorfenapyr to form pyrrole-alph-carboxylic acid, then the pyrrole group was broken to form 4-chloroglycine; (2) Chlorfenapyr was debrominated and the aliphatic ether group was cleaved from the pyrrole group, which was further broken to form 4-chlorophenylglycine. The glycine was degraded into 4-chlorobenzoic acids, which was further broken into inorganic ions and CO2.     

Copper bioavailability from breakfasts containing tea. Influence of the addition of milk

The influence of drinking tea on copper bioavailability is unclear, particularly when tea is consumed with food. A breakfast meal containing white bread, margarine, strawberry jam, cheese and tea, with or without milk, was digested in; vitro and the dialysis of copper investigated. Reference breakfasts were prepared with water and water with milk. Copper dialysability (percentage of copper dialysed) was markedly increased by tea. The influence of adding milk to tea was not significant. A second study was carried out in rats using the breakfasts containing tea and water. They were spiked with ⁶⁴Cu and given orally to the animals in a single dose. Whole-body ⁶⁴Cu retention was measured over a 4-day period after administration. In order to determine the true absorption of ⁶⁴Cu a control group of rats received the dose intraperitioneally. The results in vivo indicate a tendency to higher absorption and retention of ⁶⁴Cu with tea. Liver ⁶⁴Cu retention was significantly elevated by tea. Therefore, the presence of tea in a breakfast meal favours the formation of soluble low-molecular-weight ligands which can be absorbed and retained by rats. The concomitant increase in liver copper retetition may be associated with higher bioavailability and/or lower copper mobilisation.     

复合发酵型黑糖红茶甜米酒发酵工艺研究

以糯米、黑糖和红茶为主要原辅料,以甜酒曲和酿酒曲为发酵剂,研究复合发酵型黑糖红茶甜米酒发酵工艺,并采用单因素试验、正交试验及响应面法优化黑糖红茶汤制备工艺及黑糖红茶甜米酒发酵工艺。结果表明,黑糖红茶汤制备最优工艺条件为：黑糖添加量14%,红茶添加量6.5%,超声波功率180 W,浸提温度85 ℃,浸提时间12 min;黑糖红茶甜米酒最佳发酵工艺条件为：甜酒曲添加量0.4%、酿酒曲添加量0.25%、发酵温度30 ℃、发酵时间3.0 d。经理化与卫生指标检测,发酵型黑糖红茶甜米酒品质符合国家相关标准要求。该产品生产工艺简便,产品质量稳定,酒精度较传统糯米甜酒高,黑糖和红茶风味与香气突出,具有一定特色和创新性。     

超滤膜法提取水相中茶皂素的研究

本文以乙醇水提法提取油茶籽油后产生的水相副产物为原料,利用超滤膜法对其中丰富的茶皂素进行分离提纯。主要探索了超滤膜材料、膜孔径、茶皂素浓度、水相p H以及超滤后期加水量对茶皂素透过率以及纯度的影响。结果表明:采用截留分子量为10 k的改良纤维素复合膜(PLCGC)进行超滤,同时将水相稀释4倍至茶皂素浓度为13.13 mg/m L,p H调节至7.0,超滤后期加3倍体积的水恒容超滤,茶皂素透过率可达64.39%,纯度达84.16%。对纯化后的茶皂素进行红外光谱及液质分析,证明超滤法可以有效分离提取水相中茶皂素,实现提油后水相副产物的回收利用。      

酵母菌纯种发酵普洱茶初探

酵母菌是普洱茶发酵过程中的优势菌种之一,含有极丰富的对人体有益的营养物质、丰富的酶系统和生理活性物质,此外还能代谢产生VB1、VB2、Vc等物质,是形成普洱茶甘、滑、醇品质风格的重要因子。对从普洱茶渥堆发酵样品中分离出的5株优势酵母菌进行纯菌接种发酵试验,并对发酵后的茶样进行化学成分检测和感官评价,结果发现,酵母菌株Y5能将生茶的多酚值由28.33%降至14.54%,将茶褐素值由2.45%增至6.86%,在5株酵母菌发酵的茶样中,其茶褐素增幅最为显著。另外Y5发酵的茶样有香甜味,其滋味略苦,生津,有回甘,可以用来提高普洱茶的香气和滋味。     

液体种子种龄对姬松茸深层发酵的影响

研究了姬松茸液体种子种龄对其深层发酵过程中生物量、胞内多糖、胞外多糖和胞外纤维素酶的影响 ,以及深层发酵过程中还原糖和 pH值的变化。结果表明 ,种龄为 4d时接种 ,深层发酵产生的生物量、胞内多糖和胞外多糖均高于所选种龄为 6d和 8d时接种 ;种龄为 8d时接种生成的胞外外切 β 1 ,4 葡萄糖苷酶 (C1酶 )与内切 β 1 ,4 葡萄糖苷酶 (Cx酶 )高于种龄为 4d和 6d时接种。     

绿茶粉及其茶多酚对罗曼蛋鸡抗氧化性能的影响

探讨绿茶粉和茶多酚对罗曼蛋鸡血液抗氧化性能的影响.结果表明:绿茶粉添加量为6 g/kg,饲喂70天后,蛋鸡血清中的超氧化物歧化酶和谷胱苷肽过氧化物酶活性比对照组分别提高20.31%和8.72%(P<0.05),丙二醛含量比对照组降低37.09%(P<0.05);茶多酚添加量为1.5 g/kg,饲喂84天后,蛋鸡血清中的超氧化物歧化酶和谷胱苷肽过氧化物酶活性比对照组分别提高18.48%和5.76%(P<0.05),丙二醛含量比对照组降低19.60%(P<0.05).     

Separation and classification of the brown pigments of aqueous infusions of black tea

Rapid thin-film counter-current dialysis of a typical infusion of black tea indicates that 10–12% of the soluble solids are non-dialysable. the major components of this fraction are polysaccharides and a complex mixture which could not be separated into its protein and polyphenolic constituents. This latter complex accounts for 30–40% of the colour (E₄₅₀) of the infusion. Solvent extraction of the infusion followed by dialysis of the various extracts reveals that the polyphenol-protein complex may be approximately equated with ‘S_II thearubigins’. Chromatography of infusions and various extracts thereof on alkylated Sephadex allows a partial separation of the coloured components largely owing to differences in molecular size. At least 7 distinct zones can be recognised.