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.     

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.     

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。     

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.     

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.     

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。     

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。     

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.     

Influence of polyphenol oxidase activity and polyphenol content of tea shoot on quality of black tea

Variation in polyphenot oxidase activity and levels of total polyphenols and catechins with respect to different clones and shoot components, and its effect on quality of black tea (Camellia sinensis (L) 0 Kuntze, were studied. There was a wide variation in polyphenol oxidase activity of the different clones tested. The optimum fermentation time and polyphenol oxidase activity of different clones exhibited a hyperbolic relationship, viz y = 2.36 + 1129/x, where y = optimum fermentation time in minutes and x = polyphenol oxidase activity in μM catechol oxidised g^?1 acetone powder min^?1, with an r value of ?0.98, which is signi Jicant at P ≤ 0.001. A good non-linear relationship was found between polyphenol oxidase activity of ji-esh tea shoots of different clones and the theajavins content of corresponding black teas. Among different shoot components, bud and first leaf had higher levels of polyphenols and catechins than internodes. However, the polyphenol oxidase activity showed a reverse trend: the internodes exhibited a higher enzyme activity compared with other components. Formation of theajavins during fermentation of different shoot components was in good agreement with polyphenol oxidase activity. High performance liquid chromatographic analysis of the theaflavins fraction in tea brew of black teas made from different components of tea shoot showed that buds resulted in black tea with the highest amount of theaflavin gallates, whereas teas produced from internodes had the lowest amount of theaflavin gallates. A new factor, viz theaflavin digallate equivalent, was developed, and the significance of this factor for chemical evaluation of black tea quality is discussed in this paper.     

茶色素染色对涤纶性能的影响

以天然茶色素上染涤纶织物,探讨了不同条件下染色对涤纶织物拉伸、弯曲、压缩特性及表面特性的影响,以及对毛细效应的影响。结果表明：茶色素染色后增加了织物的柔软感、蓬松性、抗变形等能力,同时毛细效应有不同程度的提高,而织物弹性降低。     

胃蛋白酶预处理对大豆酸奶发酵过程的影响

采用乳酸菌发酵经胃蛋白酶预水解后的豆浆,优化大豆酸奶的制作工艺参数.大豆经磨粉后制成6％的豆浆,在37℃下利用胃蛋白酶处理30 min,降解其中的蛋白质.随后添加玉米糖浆使糖浓度达到6％,接种豆浆量5％的乳酸菌种子,采用恒温发酵法,在38℃下,进行厌氧发酵并冷藏24h.用占大豆干粉量0.5％的酶预处理30 min后,制...     

曲种对稠酒发酵过程中酒精度的影响

目的研究稠酒发酵过程中酒精度变化与稠酒曲种的关系。方法采用固-液2次连续发酵工艺，在适当的发酵温度下，变化不同的曲种和接种量，测定发酵醪的酒精度。结果发酵过程中酒精度随曲种及接种量的不同而变化。结论采用糖化生醇兼并型曲种，在发酵中期补加生醇能力强的曲种，有利于提高酒精度，促进产品成熟，使发酵更彻底。     

曲种对稠酒发酵过程中酒精度的影响

目的 研究稠酒发酵过程中酒精度变化与稠酒曲种的关系.方法 采用固-液2次连续发酵工艺,在适当的发酵温度下,变化不同的曲种和接种量,测定发酵醪的酒精度.结果 发酵过程中酒精度随曲种及接种量的不同而变化.结论 采用糖化生醇兼并型曲种,在发酵中期补加生醇能力强的曲种,有利于提高酒精度,促进产品成熟,使发酵更彻底.     

The use of chlorine dioxide to control Alicyclobacillus acidoterrestris spores in aqueous suspension and on apples

Alicyclobacillus acidoterrestris, a thermoacidophilic, spore-forming bacterium, has been identified as a spoilage organism in commercial, pasteurized fruit juices. This study was undertaken to evaluate chlorine dioxide for reducing numbers of A. acidoterrestris spores on laboratory media and on apples. A. acidoterrestris spores in aqueous suspension and on apple surfaces of four different cultivars were treated with several concentrations of chlorine dioxide. Spores in aqueous suspension treated with 40 ppm for 5 min were reduced by more than 4 log. Treatment with 80 ppm for 1 min and 120 ppm for 30 s resulted in about 1.8 log and 4.8 log reductions of spore viability, respectively, and treatment at 80 and 120 ppm for 5 min reduced spore viability to undetectable levels (<0.7 log CFU/ml). When applied to the surfaces of four different apple cultivars ('Red Delicious', 'Golden Delicious', 'Gala', and 'Fuji'), 40 ppm free chlorine dioxide reduced A. acidoterrestris spore numbers by 1.5, 3.2, 4.5, >4.8 log after 1-, 2-, 3-, and 4-min treatments, respectively. Spore numbers were reduced by >4.8 log with 120 ppm free chlorine dioxide after only 1-min treatment. However, there was no significant difference between apple cultivars (P>0.05) on spore reduction. These results show the great effectiveness of chlorine dioxide in controlling A. acidoterrestris spores both in aqueous suspension and on apple surfaces. There was no synergistic effect on spore reduction when chlorine dioxide treatment of aqueous suspension was followed by heat.     

发酵前澄清处理对菠萝酒品质的影响

为探讨发酵前果汁澄清处理对菠萝酒高级醇和挥发性酯类香气成分形成的影响,利用壳聚糖对菠萝汁进行澄清处理,分别对不同澄清度的菠萝汁调整可溶性固形物为20°Bx、pH3.5,接入0.03%的活性干酵母于15℃下发酵。结果表明,菠萝汁未经过澄清处理,发酵后酒的高级醇含量达0.45 g/L左右,当果汁透光率在80%时,高级醇含量降至0.27 g/L。GC-MS检测结果表明,菠萝酒的主要香气成分是辛酸乙酯和癸酸乙酯,清汁发酵菠萝酒的辛酸乙酯和癸酸乙酯相对含量分别为28.29%和38.53%,较原汁发酵的菠萝酒分别提高了8.92%和18.45%,表明发酵前对菠萝汁进行澄清处理有利于菠萝酒香气的形成。     

茶多酚对羊毛媒染性能的影响

研究了茶多酚(TP)在羊毛织物上的媒染性能,用后媒法使硫酸亚铁和硫酸铜与茶多酚络合,分别探讨了pH值、温度和时间对茶多酚吸尽率及染色深度的影响;用预媒、同浴和后媒3种方式探讨了茶多酚及金属离子浓度对茶多酚吸尽率及染色深度的影响,并对染后织物进行了牢度测试。结果表明:羊毛织物经硫酸亚铁和硫酸铜媒染分别呈紫灰色和黄棕色,在茶多酚TP-98用量5%(owf)、pH值4.1、90℃时浸渍60 min后进行媒染处理,可达到中色,并具有良好的色牢度。耐洗、耐摩擦和耐光牢度均在3级以上,沾色牢度可达到5级;铜离子络合的耐洗变色和耐光牢度均好于亚铁离子。     

Influence of different sugars on the metabolism of the tea fungus

The tea fungus is a symbiosis of osmophilic yeasts (mainlySchizosaccharomyces pombe, Saccharomycodes ludwigii, Pichia spec.) and acetic acid bacteria (Acetobacter xylinum, A. xylinoides, Bacterium gluconicum) used to produce teakwass with sugared black tea as substrate. The influence of the following sugars on the production of ethanol and lactic acid was studied using enzymatic tests: sucrose, lactose, glucose and fructose. Maximal yields of ethanol were recorded with 150 g fructose/l (8.11 g ethanol/l and 50 g sucrose/l (6.3 g ethanol/l). Lactose and glucose yielded only minor amounts of ethanol. Lactic acid was produced in relatively high concentrations with 50 sucrose/l (0.9 g acid/l); the other sugars in all tested concentrations stimulated the synthesis of this acid only to a moderate degree. The pH values of the teakwass preparations generally dropped during incubation as a result of acid formation. Test persons estimated the teakwass products as refreshing with a fruitlike taste within 6 to 10 days of incubation; prolongation of fermentation yielded a distinctly sour flavour like vinegar.

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Einfluß verschiedener Zucker auf den Stoffwechsel des Teepilzes

Zusammenfassung Der Teepilz ist eine Symbiose aus osmophilen Hefen (vor allemSchizosaccharomyces pombe, Saccharomycodes ludwigii, Pichia spec.) und Essigsäurebakterien (Acetobacter xylinum, A. xylinoides, Bacterium gluconicum), die zur Herstellung von Teekwaß aus gezukkertem Schwarztee verwendet wird. Der Einfluß folgender Zucker auf die Bildung von Ethanol und Milchsäure wurde mit Enzymtests untersucht: Saccharose, Lactose, Glucose und Fructose. 150 g/l Fructose und 50 g/l Saccharose führten zur stärksten Ethanolproduktion mit 8.11 g/l bzw. 6.3 g/l; bei Lactose und Glucose wurde demgegenüber nur wenig Ethanol gebildet. Milchsäure wurde zu 0.9 g/l bei Zusätzen von 50 g/l Saccharose produziert; die anderen Zucker in allen untersuchten Konzentrationen riefen nur eine mäßige Synthese von Milchsäure hervor. Die pH-Werte der Teekwaß-Präparate fielen im allgemeinen während der Inkubation. Testpersonen beurteilten die Teekwaß-Produkte innerhalb der ersten 6–10 Tage als erfrischend mit fruchtigem Geschmack; eine verlängerte Fermentation ergab einen essigartig-sauren Geschmack.