紫贻贝蛋白酶解过程中呈味物质释放规律和呈味肽结构

通过氨基酸分析法、超滤法、凝胶层析柱法、反相高效液相色谱法、超高分辨四极杆—飞行时间质谱法等,研究紫贻贝蛋白酶解过程中各种呈味物质的释放规律及呈味肽的结构。结果表明,酶解过程中,大分子肽逐渐降解为小分子肽,游离呈味氨基酸含量、三甲胺含量升高,肽基呈味氨基酸的含量先上升后下降,总糖含量变化不明显。pH较低时有利于低分子量肽的生成。总酸含量在酶解1h、酶解温度为50℃时最高。在50℃、pH 6.5条件下酶解2h后,紫贻贝酶解液中低分子量肽的比例较高,有机酸、糖和呈味氨基酸的释放较充分。紫贻贝酶解液中海鲜风味肽的分子量<1kDa,其结构为Cys-Ser-Val-Gln-Asp-Gln或Gln-Ala-ValAsn-Phe-Thr,不同于任何已知序列的呈味肽,其呈味阈值为0.1mg/mL。

微课让小学数学课堂更有“味”

本文结合教学实践,论述在小学数学教学中运用微课的途径,提出通过微课突破教学难点、串联知识、联系生活、渗透数学史等建议,以期让小学数学课堂更有"探索味""结构味""生活味"以及"文化味"。

Comparison of Taste Components between Triploid and Diploid Oyster

The main taste components of triploid and diploid oyster (Crassostrea gigas) were compared. Free amino acids, inosine monophosphate, succinate, trimethylamine oxide and betaine in fresh and boiled extractives were analyzed. The protein, lipids, glycogen, moisture and ash, which may affect the flavour, were evaluated. In boiled extractives, the amino acids were 394.1 mg(100 g) -1 in diploid and 183.5 mg(100 g) -1 in triploid. However, in fresh oyster extractives, they were 320.0 mg(100 g) -1 and 147.3 mg(100 g) -1 respectively. The inosine monophosphate in triploid was 44% more than that in diploid, and a little difference existed in the content of trimethylamine oxide between them. The contents of these taste components were the basis for taste flavour pattern determination.

Crystal Structure and Spectroscopic Properties of [Ni(phen)_3]Pic_2·2CH_3CN

The crystal structure of the title complex having the stoichiometric formula [Ni\|(phen) 3]Pic 2·2CH 3CN (Pic=picrate anion; phen=1,10\|phenanthroline) has been determined by single-crystal X-ray diffraction. The crystal (C 52 H 34 N 14 O 14 Ni, M r=1137.63) belongs to the triclinic system, space group P1(#2) with the following crystallographic parameters: a = 14\^130(1), b=15\^256(3), c=13.673(2); α=109.11(1), β =90.92(4), γ=66.75(3)°; V=2537\^72 3, D c=1.489g/cm 3, μ(MoKα)=4.66cm -1 , F(000)=1168, Z=2, and final R=0.062 and R w=0.078 for 4917 observed reflections (I>2.00σ(I)). The analytical results of crystal structure and spectroscopic properties show that nickel(II) cation coordination environment is a distorted octahedral geometry, the Ni 2+ ion is coordinated with six nitrogen atoms~ of three phen directly, while two picrate anions and two acetonitrile molecules do not take part in coordination~.

A Review of Triterpenoids and Their Pharmacological Activities from Genus Kadsura

Plants in genus Kadsura,belong to the Schisandraceae family including genus Schisandra and genus Kadsura,revealed folk efficacy and medicinal application in the treatment of rheumatoid arthritis and gastroenteric disorders for a long history.Previous study indicated that plants from genus Kadsura mainly contain lignans,triterpenoids and essential oils,and showed the active compounds were lignans and triterpenoids.Among all compounds from Schisandraceae family,the triterpenoids between the genus Schisandra and genus Kadsura had obvious differences.In this paper,we reviewed214triterpenoids and their pharmacological activities reported from genus Kadsura in the past30years(from1987to2017),aiming to provide reference for further study.

Effects of γ Irradiation on the Volatile Components, Texture, Color and Microstructure of Sun-cured Crispy Radish

To evaluate the effects of γ irradiation on the edible quality of sun-cured crispy radish after γ irradiation, we measured volatile components, microstructure,color, and texture. Gamma irradiation had certain effects on the composition and content of volatile components in sun-cured crispy radish, which increased the content of aldehydes, ketones and sulfur-containing substances. Increasing doses of irradiation caused declines in characteristics such as crispness, hardness,cohesiveness, and chewiness. Compared with the control, there were no obvious effects of γ irradiation on brightness L*, red-green value a* and yellow-blue value b*,and the total color difference ΔE was not significant. Scanning electron microscopy revealed that, after γ irradiation at a dose of 13.72 kGy, the vascular tissue in the radish root-skin was slightly damaged, and some small folds appeared on the cell wall of parenchymal cells in the flesh part, covered with a small amount of tiny particles. Considering the effects of γ irradiation on the quality of sun-cured crispy radish, low doses of γ irradiation are recommended, and this study can be a reference for the application of γ irradiation in the preservations of radish and similar vegetable products.

菲尔德-费曼模型中的介子碎裂函数

从菲尔德-费曼的叠代模型出发,考虑到入射夸克的味结构,研究了π介子的碎裂函数D_u~π^+,D_d~π^+,和D_s~π^+,并将分析结果和实验数据进行了比较,对K介子的碎裂函数D_s^K^+(z),D_u^K^+(z),D_s^K^+(z)和D_d^K^+(z)作出的预言将被进一步的实验检验。

Chemical constituents from the fruit of Schisandra Chinensis

A new 18-norschiartane bisnortriterpenoid,12-angeloyl wuweizidilactone I(1)and nine known compounds,wuweizidilactone I(2),wuweizidilactone G(3),deoxychizandrin(4),sasanquin(5),orcinol-O-β-D-glucopyranoside(6),okanin-4-methyl ether-3’-O-β-Dglucopyranoside(7),evemic acid(8),juglansol A(9)and 2-acetoxybenzyl benzoate(10),were isolated from the fruits of Schisandra Chinensis.Their structures were established by a combination of spectroscopic data analysis in addition to comparison with literature data.Compound 1 was new,and compounds 6–10 were isolated from Schisandrae Chinensis for the first time.

The Majorana neutrino mass matrix indicated by the current data

The Majorana neutrino mass matrix combines information from the neutrino masses and the leptonic mixing in the flavor basis. Its invariance under some transformation matrices indicates the existence of certain residual symmetry. We offer an intuitive display of the structure of the Majorana neutrino mass matrix, using the whole set of the oscillation data. The structure is revealed depending on the lightest neutrino mass. We find that there are three regions with distinct characteristics of structure. A group effect and the μ-T exchange symmetry are observed. Six types of texture non-zeros are shown. Implications for flavor models are discussed.