啤酒中异-α酸和蛋白质含量对啤酒泡持性的影响

研究以11°P不同品牌的啤酒为研究对象,分别利用国标法、反相高效液相色谱法(RP-HPLC法)、二喹啉甲酸法(BCA法)和十二烷基磺酸钠-聚丙烯酰胺凝胶电泳技术(SDS-PAGE技术)检测了啤酒泡持性、异-α酸含量、泡沫蛋白质的浓度及蛋白质Z与脂转移蛋白(LTP)含量。结果显示,异-α酸中的异合葎草酮及总蛋白质含量与泡持性关系较密切,但是单一蛋白质Z或LTP含量与泡持性不太密切。

极谱双点滴定法测定啤酒花中α酸的含量

本文提出用甲醇萃取啤酒花中的α酸,采用极谱双点滴定法测定α酸的实验方法,并对实验条件进行了详细研究。该法简便,快速。测定结果与部颁标准相符,且重现性优于部颁标准。

应用β环糊精分离酒花提取物中异构化的顺、反式异-α酸

酒花仪酸的异构体顺、反式异-α酸，是啤酒中主要的苦味物质。研究表明顺式异-α酸比反式异-α酸稳定。因此，分离出顺式异-α酸可以生产出相对稳定的啤酒。采用β环糊精来对它们进行分离，可得到最纯的顺式异-α酸。最佳条件是用水作溶剂在70℃进行包合，β环糊精的质量与水的体积比为1：8，样品异一仅酸总量与β环糊精的摩尔比为1：1，沉淀两天后，将上清液进行超滤，以去除残留的B环糊精。将异-α酸与β环糊精的摩尔比变为4：1，其他条件不变，可得到最纯的反式异-α酸。用甲醇可将反式异构体从β环糊精混合物中分离出来。在加酒花的饮品中，这种方法可以满足大规模生产的需要。

酒花中α—酸的氢化方法的初步研究

应用正交试验，对影响α酸氢化的诸因素中的7因素2水平进行了对比研究。结果表明，各试验间四氢异α酸的含量差异明显，分析了造成差异的原因，从而找到了α酸氢化的较优条件。

日本高α－酸含量酒花新品种

日本高α－酸含量酒花新品种摘要日本麒麟有限责任股份公司培育出三株高α－酸含量的酒花新品种：Ｔｏｙｏｍｉｄｏｒｉ、Ｋｉｔａｍｉｄｏｒｉ和东方黄金（ＥａｓｔｒｎＧｏｌｄ）。它们的α－酸含量分别为１２．２％、１５．４％和１７．３％。这些新品种的α－酸含量，...

利用HPLC法和UV法评价酒花及其异构化制品的质量

本文主要探讨了分析酒花α酸、异构酒花浸膏异α酸的HPLC法和UV（分光光度）法的优缺点及其局限性，并将HPLC法、UV法相互结合，引入“α酸含量（HPLC法）”、“β酸含量（HPLC法）”“异α酸含量（HPLC法）”、“α酸／β酸比值”、“合棒草酮／α酸比例”、“HPLC峰纯”等新的评价指标，以有效地评价酒花及异构化浸膏的质量。

老化的颗粒酒花对啤酒发酵抗氧化能力的影响

分析老化后酒花的主要成分,研究发现在酒花老化过程中α酸和β酸发生氧化降解,前期生成异α酸,随着老化的进行,继而产生葎草灵酮(humulinone)和希鲁酮(hulupones)等衍生氧化物。酒花中的总多酚含量逐渐减少,具有抗氧化性的酚酸也发生氧化聚合,使用液相色谱检测几乎无响应峰。并测定总多酚、DPPH清除率、TRAP值、TBA值等抗氧化指标来分析老化的酒花对麦汁和啤酒的抗氧化能力影响,实验发现老化的酒花对麦汁和啤酒的抗氧化能力影响较大,尤其是风味稳定性系数SI值,波动最为明显。

Chemical Constituents of Pu-erh Tea and Its Inhibition Effect on α-amylase in vitro

[Objective]The aim was to clarify the chemical substance basis of hypoglycemic and lipid-lowering effects of Pu-erh Tea. [Method]Pu-erh Tea was extracted with 95% ethanol,followed by petroleum ether,chloroform,ethyl acetate and n-butanol extraction,after the further purification and through the NKA-9 macroporous resin and many times of Sephadex column chromatography,two compounds were isolated,in the same time,the effect of Uracil and Gallic acid on α-amylase was studied. [Result]The Uracil and Gallic acid were isolated and identified respectively from Pu-erh Tea and the Uracil was firstly isolated from Pu-erh Tea; Gallic acid had strong inhibition on α-amylase. [Conclusion]It could provide some theories on the hypoglycemic and lipid-lowering effects of Pu-erh Tea.

啤酒苦味物质控制技术探讨

影响啤酒苦味质量的因素很多,文章从苦味值的检测、酒花添加量的计算、糖化酒花添加工艺等影响因素分析、控制,达到提高啤酒苦味质量的目的。

Construction of Fusion Expression Vector of α-galactosidase-EGFP in Cucumber

[Objective] The research aimed to construct the fusion protein expression vector of α-galactosidase-EGFP （enhanced green fluorescent protein） in cucumber controlled by CaMV35S promoter.[Method] CaMV35S promoter sequence and the coding region of EGFP were amplified by polymerase chain reactions （PCR） with vector pCambia 1303 as the template.Using reverse transcript PCR technology,with total RNAs of cucumber as template,the coding region of acid α-galactosidase Ⅰ in cucumber was amplified.The above three fragments were inserted into the multiple cloning sites of expression vector pCambia 1381c.The fusion expression vector of α-galactosidase-EGFP located at the C-terminal of the target genes was constructed.[Result] After enzyme digestion and sequencing,the fusion expression of α-galactosidase-EGFP in cucumber was constructed successfully.[Conclusion] The research laid the experimental basis for further study on the subcellular localization of α-galactosidase in cucumber.

Screening, Identification and Fermentation Property of a Yeast Strain R6 Accumulating Alpha-ketoglutaric Acid

A yeast strain R6 was obtained by the method of thiamine（VB1） auxotrophic negative selection from the edible oil-polluted soil in Zibo, China. Physiological and biochemical experiments revealed that strain R6 shared common feature with Rhodotorula mucilaginosa according to the API 20 C AUX yeast identification system which has been tested previously. Furthermore, the 18 S r DNA gene of strain R6 was amplified and sequenced. Phylogenetic analysis based on the 18 S r DNA sequence and the relatives indicated that R6 shared 99% homologies with the members of R. mucilaginosa, suggesting that strain R6 belonged to R. mucilaginosa.Investigation showed that strain R6 possessed the capacity of accumulating exocellular alpha-ketoglutaric acid（alpha-KG）. Finally, the fermentation conditions of R6 to accumulate alpha-KG was optimized by controlling each single fermenting variable and detected through high performance liquid chromatography（HPLC）. Results showed that both VB1 and Ca CO3 in fermentation medium were the key factors influencing the cumulant of alpha-KG. The discovery of natural auxotrophic strain R6 not only broadened the microbial resource which can achieve lots of alpha-KG production through fermentation, but also laid a foundation for further fermentation regulation to achieve excessive alpha-KG accumulation.

Distribution of Sediment Chloroplastic Pigments in the Southern Yellow Sea,China

The distribution of sediment chloroplastic pigments (Chl-a, i.e. chlorophylla and Pha-a, i.e. phaeophorbide a) in the Southern Yellow Sea of China was studied. Samples werecollected from four cruises in January and June 2003, and January and June 2004. The results showthat the vertical distribution of Chl-a and Pha-a in the sediment layers 0-2cm, 2-5cm and 5-8cm,follows a stable ratio, 5:3:2. The average ratio of Pha-a to Chl-a in sediment is 2.83. Spearman2-tailed rank correlation analysis shows that Chl-a and Pha-a contents in each sediment layer have ahighly significant correlation. The average contents of Chl-a and Pha-a in the sediment of the0-8cm layer in the investigated area are 0.31-0.47 μg g^(-1) and 1.28-1.40 μg g^(-1) sediment (dryweight), respectively. The average Chl-a and Pha-a contents in sediment are higher in summer thanin winter. ANOVA analysis shows that there is a highly significant variation among the Chl-acontents (P = 0.002 【 0.01) of the four cruies, but this is not true for the case of Pha-a content(P = 0.766 】0.05). The average Chl-a and Pha-a contents in the 2 sediment layers (0-2cm and 2-5cm)have significant or highly significant correlations with organic matter (OM), median diameter(Md_φ), silt plus clay percentage in the January 2003 cruise. In the June 2003 cruise, the averageChl-a content in the 3 sediment layers (0-2cm, 2-5cm, and 5-8cm) has a significant correlation withmeiofauna biomass, and Pha-a content has highly significant correlations with water depth, bottomwater temperature, OM and Md_φ. The contents of Chl-a and Pha-a are lower than those in estuariesand intertidal areas, but close to those in the same area studied previously.

Preparation of α-calcium sulfate hemihydrate whiskers with high aspect ratios in presence of a minor amount of CuCl_2·2H_2O

In order to produceα-calcium sulfate hemihydrate(α-CaSO4·0.5H2O)whiskers with high aspect ratios,a minor amount of CuCl2·2H2O was used as the modifying agent in the process of hydrothermal treatment of calcium sulfate dihydrate(CaSO4·2H2O)precursor.The presence of 2.60×10–3 mol/L CuCl2·2H2O resulted in the increase of the aspect ratios ofα-CaSO4·0.5H2O whiskers from 81 to 253.The preferential adsorption of Cu2+on the negative{110}and{100}facets ofα-CaSO4·0.5H2O crystal structures was confirmed by EDS and XPS.And ATR-FTIR demonstrated the ligand adsorption of Cu2+on the surface ofα-CaSO4·0.5H2O whiskers.The experimental results reveal that the whiskers with high aspect ratios are attributed to the adsorption of Cu2+,which promotes the 1-D growth ofα-CaSO4·0.5H2O whiskers along the c axis.

α-Lipoic acid protects against cholecystokinin-induced acute pancreatitis in rats

AIM: α-Lipoic acid (ALA) has been used as an antioxidant.The aim of this study was to investigate the effect of α-lipoic acid on cholecystokinin (CCK)-octapeptide induced acute pancreatitis in rats.METHODS: ALA at 1 mg/kg was intra-peritoneally injected, followed by 75 μg/kg CCK-octapeptide injected thrice subcutaneously after 1, 3, and 5 h. This whole procedure was repeated for 5 d. We checked the pancreatic weight/body weight ratio, the secretion of pro-inflammatory cytokines and the levels of lipase,amylase of serum. Repeated CCK octapeptide treatment resulted in typical laboratory and morphological changes of experimentally induced pancreatitis.RESULTS: ALA significantly decreased the pancreatic weight/body weight ratio and serum amylase and lipase in CCK octapeptide-induced acute pancreatitis. However,the secretion of IL-1β, IL-6, and TNF-α were comparable in CCK octapeptide-induced acute pancreatitis.CONCLUSION: ALA may have a protective effect against CCK octapeptide-induced acute pancreatitis.

Synthesis and Crystal Structure of O,O-Dimethyl-N-(β-triphenylgermanyl)propionyl-α- aminobenzylphosphonates

The title compound (C30H32NO4PGe), O,O-dimethyl-N-(β-triphenylgermanyl) propionyl-α-aminobenzylphosphonates was synthesized by a convenient method, and its crystal structure was determined by single-crystal X-ray diffraction. The crystal is triclinic, space group P-1 with parameters: a=9.7753(5), b=11.5773(5), c=13.5059(6) ?, α=104.185(1),β= 95.971(1), γ =96.727(1)°, V=1457.63(12) ?3, Z=2, Mr=574.13, Dc=1.308 g/cm3, λ=0.71073 ?, μ = 1.139mm-1, and F(000)=596. The structure was solved by direct methods. The structure was refined to R=0.0257, wR=0.0705 for 5080 observed reflections with I >2σ(I).The result of structure analysis indicates that atom Ge is sp3 hydridized because the arrangement of the four carbon atoms bonded to it is a distorted tetrahedron. The geometry of the three phenyl groups linking with the Ge atom looks like a propeller form.

Content and Partial Characterization of Unknown N in Humic Acids

INTRODUCTION Nitrogen is a key component of soil organic matter. Only when we have succeeded in characterizing the major part of organic N-containing compounds will we be able to understand fully the transformation reactions in the soil and to use soil-N more efficiently. However, only about 1/ 4——1/ 2 of the total N in humic acid (HA), one of the major constituents of soil organic matter, can be accounted for as amino acids and amino sugars, and most of the remainder has still to be accounted for. It has been

Production of γ-linolenic acid and stearidonic acid by Synechococcus sp.PCC7002 containing cyanobacterial fatty acid desaturase genes

Genetic modifi cation is useful for improving the nutritional qualities of cyanobacteria. To increase the total unsaturated fatty acid content, along with the ratio of ω-3/ω-6 fatty acids, genetic engineering can be used to modify fatty acid metabolism. S ynechococcus sp. PCC7002, a fast-growing cyanobacterium, does not contain a Δ6 desaturase gene and is therefore unable to synthesize γ-linolenic acid(GLA) and stearidonic acid(SDA), which are important in human health. In this work, we constructed recombinant vectors Syd6 D, Syd15 D and Syd6Dd15 D to express the Δ15 desaturase and Δ6 desaturase genes from Synechocystis PCC6803 in Synechococcus sp. PCC7002, with the aim of expressing polyunsaturated fatty acids. Overexpression of the Δ15 desaturase gene in S ynechococcus resulted in 5.4 times greater accumulation of α-linolenic acid compared with the wild-type while Δ6 desaturase gene expression produced both GLA and SDA. Co-expression of the two genes resulted in low-level accumulation of GLA but much larger amounts of SDA, accounting for as much to 11.64% of the total fatty acid content.

Effects of α-tocopheryl acetate supplementation in preslaughter diet on antioxidant enzyme activities and fillet quality of commercial-size Sparus macrocephalus

This study examined the effects of dietary α-tocopheryl acetate supplementation on antioxidant enzyme activities and fillet quality in commercial-size Sparus macrocephalus. Three hundred fish [main initial weight （350±12） g] were divided into three groups （E250, E500 and El000） and reared in 9 cages. The fish were fed for 8 weeks with three diets containing different levels of dietary α-tocopheryl acetate （289, 553, 1069 mg/kg）. Over the experimental period, fish were fed to satiation and reached a final mean weight of （465±28） g without significant body weight difference and proximate composition difference. Fillet α-tocopherol was significantly （P〈0.05） different between groups, reaching levels of 14.2, 22.1, 30.9 pg/mg fillet for groups E250, E500 and El000, respectively. Total serum superoxide dismutase （SOD） activity increased significantly （P〈0.05） in fish fed the diets high in α-tocopheryl acetate, but serum glutathione peroxidase （GPX） activity was unaffected. In storage on ice, fillets of fish fed the diets high in α-tocopheryl acetate exhibited significantly lower （P〈0.05） levels of oxidation. These results suggested that increased dietary α-tocopheryl acetate could increase its flesh deposition, increase the activity of SOD and prevent lipid peroxidation ofSparus macrocephalus fillets in retail storage on ice.

Effect of α-synuclein on the promoter activity of tyrosine hydroxylase gene

Objective To approach the associated mechanism by which α-synuclein （α-Syn） might regulate the metabolism of dopamine. Methods A DNA fragment, located at --495 to ＋25 of the human tyrosine hydroxylase （TH） gene, was amplified by PCR and inserted into the pGL3-Basic luciferase reporter vector. The recombinant plasmid pGL3-THprom was transfected into a dopammergic cell line MES23.5 or a α-Syn over-expressed MES23.5 （named MES23.5/hα-Syn^＋）. The promoter activity was detected by the Dual Luciferase Assay System. Results The luciferase activities in the MES23.5 cells transfected with pGl.,3-Basic, pGL3-THprom, and pGL3-Control vectors were 5.60±0.67, 26.80±4.11, and 32.90±4.75, respectively. On the other hand, the luciferase activity of pGL3-THprom in the MES23.5 （26.80±4.11） was significantly higher than that in the MES23.5/hα-Syn^＋（14.40±0.61） （P〈0.01）. Conclusion These results indicate that the -495 to ＋25 region in the TH gene possesses promoter activity for controlling the gene expression, and that α-Syn may negatively regulate the metabolism of dopamine by affecting the function of TH promoter as a trans-acting factor.