钝顶螺旋藻藻蓝蛋白的稳定性试验研究

用冻融的方法制备钝顶螺旋藻(Spirulina platensis)藻蓝蛋白并对纯化后的藻蓝蛋白稳定性进行了初步研究。提取后的粗提液经羟基磷灰石柱层析纯化后其纯度(A621／A280)达3.1温度、酸碱度、乙醇对藻蓝蛋白稳定性有较大影响；NaCl、苯甲酸钠、柠檬酸等食品添加剂对其稳定性影响较小。     

Leisure, home, and occupational physical activity and cardiovascular risk factors in postmenopausal women. The Postmenopausal Estrogens/Progestins Intervention (PEPI) Study

OBJECTIVE: To examine the associations between self-reported leisure, home, and occupational physical activity and selected cardiovascular risk factors. METHODS: A cross-sectional analysis of baseline data from the Postmenopausal Estrogen/Progestins Intervention Trial was performed in 851 women aged 45 to 64 years. Outcomes were levels of high-density lipoprotein cholesterol, insulin (2 hours after challenge), fibrinogen, systolic blood pressure. Race-stratified models were adjusted for age, smoking, alcohol, and previous noncontraceptive estrogen use. Models were also run with body mass index as an additional covariate. RESULTS: In white women, leisure physical activity was positively associated with levels of high-density lipoprotein cholesterol (P = .001) and inversely associated with levels of insulin (P = .04) and fibrinogen (P = .02). Compared with high-density lipoprotein cholesterol levels in the inactive and light leisure physical activity groups, moderate (P < .001) and heavy (P = .004) leisure activities were associated with higher high-density lipoprotein cholesterol levels. High-density lipoprotein cholesterol levels in the heavy leisure physical activity group were significantly higher than those in the moderate group (P = .01). Compared with lesser levels of leisure physical activity, significantly lower mean values of fibrinogen (P = .02) and insulin (P = .01) were associated with the highest-intensity leisure physical activity. Home physical activity was positively related to high-density lipoprotein cholesterol level (P = .01); relative to lower levels of home physical activity, the heavy home physical activity group demonstrated significantly higher mean high-density lipoprotein cholesterol levels. The effects of leisure and home physical activities were independent of each other. systolic blood pressure did not vary by leisure, occupational, or home physical activity. CONCLUSION: The unique relationships between type of physical activity and cardiac risk factors underscore the necessity of including multiple domains of activity in epidemiologic studies of epidemiologic studies of physical activity in women.     

Dietary patterns associated with a low-fat diet in the national health examination follow-up study: identification of potential confounders for epidemiologic analyses

To identify systematically the nutrient and food group intakes associated with a low-fat diet, the authors used the detailed dietary information collected from 10,306 individuals aged 32-86 years in the 1982-1984 National Health Epidemiologic Follow-up Study. Intakes of vitamin C and percentages of calories from carbohydrates, dietary fiber, poultry, low-fat dairy products, fruits, vegetables, cereals, and whole grains were markedly higher, while intakes of protein, total fat, saturated fat, oleic and linoleic acids, cholesterol, sodium, all red meats, high-fat dairy products, eggs, nuts, white bread, fried potatoes, desserts, fats, and oils were much lower in the quartile with the lowest percentage of calories from fat. These dietary patterns associated with a low-fat diet were essentially constant across strata of age, sex, race, and socioeconomic status. This study suggests that individuals on a low-fat diet substitute certain carbohydrate-rich foods such as fruits and vegetables for fat. Given these associations between low-fat diets and other dietary factors independently associated with certain cancers, these dietary factors should be considered potential confounders in studies of dietary fat and these cancers.     

B-scan ultrasonography in ophthalmic diseases

Real time B-scan ultrasonography was utilised on 318 eyes of 298 patients for evaluation of 285 (90%) eyes with opaque media; three (1%) eyes, with clear media but suspected intraocular abnormalities and for proptosis in 30 (9%) cases. Two hundred and nine (66%) eyes had one or more detectable abnormalities. The most common abnormality was retinal detachment (39%) followed by vitreous opacities (31%), eye ball size abnormalities (12%), intraocular foreign bodies (4%), posterior staphyloma (3%) and retinal detachment with vitreous opacities (2%). Twenty eight out of thirty patients evaluated for proptosis had abnormal orbital tissue patterns. Solid and cystic tissue patterns each accounted for 32% of the abnormal orbital studies followed by thyroid orbitopathy (25%), non specific (7%), and infiltrative (4%) tissue patterns. Detailed findings of B-scan ultrasonographic study is given in this paper. The paper reports further experience with the procedure in a developing country. In areas where other imaging techniques are not available the procedure is a valuable method of evaluating the eye and orbit for any detectable abnormalities and for planning management.     

Preparation and antihypertensive activity of peptides from Porphyra yezoensis

This research was to develop a antihypertensive peptide, an efficient angiotensin converting enzyme (ACE) inhibitor (ACEI), from Porphyra yezoensis. Seven commercial enzymes were screened and then enzymatic hydrolysis conditions were optimised. The results showed that alcalase was the most effective for hydrolysis and its optimum conditions for achieving the highest antihypertensive activity of peptide were 1.5% substrate, 5% alcalase, pH 9.0, and temperature of 50 °C at a hydrolysis time of 60 min. The antihypertensive peptide produced under the optimum conditions had a high ACE inhibition rate of 55.0% and a low IC₅₀ value of 1.6 g/l and remained at high stability at temperatures of 4, 25, and 37 °C, pH values of 2.0 and 8.0, and after pepsin and trypsin treatments. Major proteins from P. yezoensis were glutelin, albumin, and gliadin. The albumin and glutelin had higher hydrolysis rates than the gliadin, but the IC₅₀ value of glutelin was the lowest, which indicated that the antihypertensive peptide from glutelin was more functional.     

Modeling of drying and ameliorative effects of relative humidity (RH) against β-carotene degradation and color of carrot (Daucus carota var.) slices

Food Science and Biotechnology - Drying and β-carotenes retention kinetics were predicted using models in relative humidity (RH) drying condition. This was achieved by drying carrot slices...     

Biobased Poly-phosphonate Additives from Methyl Linoleates‡

Poly-dialkyl phosphonates were synthesized by reacting methyl linoleate with dimethyl, diethyl, and di-n-butyl phosphites in the presence of free radical initiator and positively identified and characterized using gas chromatography–mass spectrometry (GC-MS), nuclear magnetic resonance (NMR; ¹H, ¹³C, ³¹P), and Fourier transform infrared (FTIR). Neat poly-dialkyl phosphonates and their blends in high-oleic sunflower oil (HOSuO) and polyalphaolefin (PAO-6) base oils were investigated for their physical, chemical, and tribological properties. At room temperature, the poly-dialkyl phosphonates displayed much better solubility in HOSuO than in PAO-6. Solubility in the base oils increased in the order dimethyl?<?diethyl?<?di-n-butyl. Relative to methyl linoleate, the neat poly-dialkyl phosphonates displayed higher density, higher kinematic viscosity, higher oxidation stability, and better cold flow (lower pour point and cloud point) properties. As an additive (0–10% w/w) in HOSuO, increasing concentration of poly-di-n-butyl phosphonate resulted in increasing onset and peak oxidation temperatures and decreasing cloud point. Poly-di-n-butyl phosphonate blends in HOSuO also showed lower four-ball antiwear (AW) coefficient of friction (COF) and wear scar diameter (WSD) than corresponding blends with zinc dialkyl dithiophosphate (ZDDP). As an additive (0–10% w/w) in PAO-6 base oil, poly-di-n-butyl phosphonate displayed lower four-ball antiwear COF and comparable WSD relative to similar blends of ZDDP in PAO-6. The results indicate that poly-dialkyl phosphonates are promising biobased AW additives with comparable or better performance than current petroleum-based commercial AW additives such as ZDDP.     

Friction properties of chemically modified starch

Starches of varying chemical structures were esterified with anhydrides, formulated into dry film lubricants with the addition of canola oil, and its friction properties investigated. In the absence of canola, chemically modified starch displayed a very high coefficient of friction (COF). Addition of canola resulted in a sharp decrease in COF, which decreased with increasing [canola] until it attained a minimum and constant value that was independent of the further increase in [canola]. This observation was attributed to the adsorption of the canola oil onto starch due to H‐bonding between the ester groups of the canola triglycerides and the free hydroxyl groups of starch. Analysis of the [canola] vs COF data using the Langmuir adsorption model showed stronger adsorption of canola to modified starch with a lower degree of substitution (DS). This was attributed to the availability of more free hydroxyl group adsorption sites on starches with lower DS than those with higher DS. Copyright © 2008 John Wiley & Sons, Ltd.     

酶解与体外模拟胃肠消化对脱脂羊奶粉ACE抑制活性的影响

本研究旨在探究商业蛋白酶酶解与体外模拟胃肠消化对高消化率的脱脂羊奶粉释放ACE抑制肽的影响,以评价脱脂羊奶粉酶解必要性及所需酶解程度。采用中性蛋白酶、碱性蛋白酶、复合蛋白酶和风味蛋白酶对脱脂后的圭山羊奶粉进行酶解反应,并对脱脂羊奶粉及其酶解物进行体外模拟胃肠消化,测定酶解液及模拟胃肠消化液的多肽含量、ACE抑制活性以及分子量分布。研究发现,羊奶粉经过体外模拟胃肠消化后,消化液的多肽含量与ACE抑制率分别达到20.81 mg/mL和62.55%;而经过碱性蛋白酶和风味蛋白酶的适度酶解,其模拟胃肠消化液多肽含量与ACE抑制活性反而下降;经过复合蛋白酶的适度酶解,其模拟胃肠消化液的多肽含量与ACE抑制活性小幅度提高,分别达到22.67 mg/mL和69.29%;经过中性蛋白酶的适度酶解,其模拟胃肠消化液多肽含量与ACE抑制活性均显著提高,分别达到23.76 mg/mL和81.10%。分子量分布结果显示,经过体外模拟胃肠消化后,<1000 Da的小分子肽由酶解液中的70.77%提高到90%。综上,圭山羊奶粉经过体内胃肠消化就可以释放出较多的ACE抑制肽,而经过中性蛋白酶酶解至水解度8%后...     

醋醅中细菌菌株的分离鉴定及系统学分析

对取自陕西省的醋醅中分离得到的菌株进行16S rRNA基因序列的系统学分析.通过聚合酶链式反应(PCR)的扩增,结合16S rRNA基因序列的同源性分析,比较未成熟醋醅样品与已成熟醋醅样品中细菌组成的差异,并构建两者的系统发育树.结果表明,未成熟醋醅样品呈现较高的细菌多样性,并且在设定一个假定阈值后,2个醋醅样品中的优势种群均为枯草芽孢杆菌(Bacillus subtilis)和解淀粉芽孢杆菌(Bacillus amyloliquefaciens),仅在数量上存在差异.