维生素E对β-胡萝卜素纳米乳液性质及其饮料稳定性的影响

为提高β-胡萝卜素的水溶性和稳定性,本研究以吐温80、吐温60和磷脂为乳化剂,维生素E为抗氧化剂制备了纳米乳液.测定了纳米乳液的粒径、透光率、色价、储藏稳定性和应用稳定性.结果显示,维生素E对纳米乳液粒径和透光率有轻微影响,对包埋率和色价没有影响.在25、37℃和光照下储藏28 d期间纳米乳液的透光率没有发现明显变化,...     

微波对植物油中维生素E抗氧化性能的作用

阐述维生素Ｅ结构的及其抗氧化机理，综述微波作用下植物油中维生素Ｅ抗氧化性能的变化。     

生物活性物质的抗氧化能力评价方法及其研究进展

准确评价生物活性物质的抗氧化能力已经成了氧化与抗氧化研究领域的热点问题,综述了国际上当前比较流行的几种体外抗氧化能力评价方法,如:2,2'-连氮-双-(3-乙基苯并噻唑-6-磺酸)-二铵盐法、1,1-二苯代苦基苯肼法、铁离子还原/抗氧化能力测定法、氧自由基吸收能力测定法、化学发光法,以及体内抗氧化能力评价方法的关键点.     

复配抗氧化剂对玉米油抗氧化作用的研究

采用响应面法研究开发一种复配抗氧化剂配方,以提高玉米油的抗氧化作用。通过Schaal烘箱加速氧化法,以玉米油过氧化值(POV)为响应值,建立了维生素E、茶多酚、抗坏血酸棕榈酸酯对玉米油过氧化值影响的方程模型。确定3种抗氧化剂的最佳配方参数,并进行验证试验。结果显示,复配抗氧化剂最优配方为维生素E添加量0.125 2%,茶多酚添加量为0.034 5%,抗坏血酸棕榈酸酯为0.016 1%,此时过氧化值响应值为4.299mmol/kg,对玉米油的抗氧化效果显著。     

天然维生素和合成维生素的活性与标识

某些天然维生素和合成维生素在生物活性方面存在较大差异 ,特别是维生素E和维生素A源——类胡萝卜素。本文着重讨论了天然和合成维生素E、β -胡萝卜素的区别及活性差异 ,并对如何标识提出建议     

维生素E对致敏大鼠机体敏感性的影响

目的研究补充不同剂量、不同接触时间的维生素E对致敏SD大鼠机体敏感性的影响。方法取8周龄雌性SD大鼠,按体重随机分为5组,每组25只,每天经口分别给予不同剂量的维生素E(2.3、6.9、13.8mg/kg),在第2周、3周、4周、5周、6周时,每组分别取出5只动物,腹腔注射给予10 mg/只OVA致敏,一周后使用50 mg/只OVA刺激,检测各组动物血清中总Ig E、特异性Ig E和Ig G1、血浆中组胺、m MCP-1和细胞因子(IFN-γ,IL-4)的水平,大刺激后处死动物,取心脏、肝、脾、肾、胸腺、空肠、肠系膜淋巴结等脏器,并对这些脏器进行组织病理学观察。结果经口给予高剂量维生素E 6周,OVA产生的免疫学反应强度受到了显著的抑制作用,总Ig E、特异性Ig E、特异性Ig G1、IL-4以及组胺水平显著降低,IFN-γ水平显著升高,随接触时间的延长呈增高的趋势。且高剂量处理组动物免疫学反应强度显著低于OVA对照处理组,对致敏SD大鼠的机体敏感性起到了有效的调节作用。结论维生素E能够降低致敏动物机体对卵白蛋白的敏感性,也抑制了免疫系统对卵白蛋白产生的免疫学反应。     

提高维生素E抗氧化效果的研究

维生素E(以下简写V_E)对油脂的抗氧化效果是肯定无疑的。然而它的效果与它的同分异构体的含量、添加量以及实验油(油脂)的种类、储存温度等条件密切相关。虽然V_E比合成抗氧化剂的抗氧化效果差些,但V_E是天然抗氧化剂,添加在食用油或油脂食品中,可解除人们的不安心理。为了在实践中更有效地使用V_E,本文对使用柠檬或L抗坏血酸(以下简写V_C)作为增效剂提高V_E抗氧化效果进行了研究。研究结果表明,以柠檬酸作为增效剂,添加于猪油中,60℃烘箱试验V_E的抗氧化性提高了,比单独使用V_E效果好;以柠檬酸或V_C作增效剂添加于机榨菜油中,室温储存,V_E的抗氧化效果明显提高。两者均比单独使用V_E抗氧化效果好;以柠檬酸或V_C作增效剂添加于精炼棉油中,室温储存,对于提高V_E抗氧化效果不明显。     

5株微生物抗氧化作用的初步研究

以食品中分离得到的27株细菌和55株酵母为研究对象,进行体外抗氧化性能的研究。通过自由基（DPPH、·OH、·O2^-）清除试验、脂质过氧化抑制试验、还原能力和菌体在H2O2中耐受试验等,筛选出6株高抗氧化性能菌（B1～B4、B6）。结果表明：B1～B4、B6的完整菌体对清除DPPH、·OH和抑制脂质过氧化有明显的效果;除B6外,其他4株菌体的还原能力均高于100μmol／L的半胱氨酸盐酸盐;在1mmol／L的H2O2中,试验用6株菌的耐受能力远高于用于对照的保加利亚杆菌。     

食品中微生物抗氧化作用的初步研究

通过清除DPPH自由基和抑制脂质过氧化能力的实验,从不同来源的菌种中筛选出3株高抗氧化活性菌(B2、B3、84),并通过还原能力测定、清除羟自由基实验对其体外抗氧化能力进行比较研究.结果表明,B2、B3和B4活菌体对DPPH自由基的清除率和脂质氧化的抑制率均超过50%,还原能力均高于对照组(100μmol/L的L-半胱氨酸),羟自由基清除率分别为59.8%、61.O%和64.6%,同时发现3株菌菌体的各项抗氧化指标明显高于相应发酵液.     

染发——维生素B：常染发者应补充维生素B吗？

很多人感觉烫完发后,头发干枯发涩,没有光泽。这是由于在烫发的过程中,药水中的碱性成分和氧化作用,使头发表层的毛小皮遭到破坏,头发内部的水分和营养成分流失,头发的角质蛋白发生了变性。在烫头发前后一个月内可以服用复合维生素B和β-胡萝卜素。     

脂溶性维生素对多种慢性疾病治疗作用的研究进展

综述脂溶性维生素抗炎、抗氧化等生物活性对糖尿病、骨质疏松、慢性肾脏病等慢性疾病治疗作用的研究进展。     

不同贮存条件下生菜中维生素C和E含量分析

采用高效液相色谱法对在5个时间梯度处理、2个温度梯度处理条件下生菜叶片中维生素C和E含量进行了分析。结果表明,维生素C对贮存时间和温度特别敏感。低温或室温贮存1d的生菜中维生素C含量均损失50%以上,而维生素E含量包括α-生育酚含量反而有所提高;但低温或室温贮存3d后生菜中维生素C含量和维生素E含量特别是α-生育酚含量均急剧下降。因此,从营养利用的角度考虑,生菜的贮存以低温1～3d为宜,室温和长时间贮存会造成维生素C和E的大量损失。     

Effects of breed and a concentrate or grass silage diet on beef quality in cattle of 3 ages. II: Meat stability and flavour

This study examined the effect of breed and diet on meat quality, defined as lipid stability, colour shelf life and sensory quality. Ninety-six steers were used, half Aberdeen Angus (AA) cross and half Holstein-Friesian (HF). They were reared from 6 months of age on a standard concentrate diet or grass silage and slaughtered at 14, 19 or 24 months of age. Breed had small effects on quality with lower lipid stability in muscle of 24 month-old HF (P<0.05). Sensory scores were similar between the breeds, the few differences being in favour of AA. Diet had the biggest effects on meat quality, in all 3 age groups. The grass silage diet produced higher plasma and muscle levels of vitamin E, lower lipid oxidation in loin steaks measured at 4 and 7 days of retail display and better colour stability (saturation) during shelf life in MAP (O(2):CO(2); 75:25) (all P<0.001). The high values for lipid oxidation in the concentrate-fed steers were linked to high muscle PUFA concentrations and low levels of vitamin E.     

Effect of different dietary levels of natural-source vitamin E in grow-finish pigs on pork quality and shelf life

Improving pork quality and shelf life is important in today’s swine industry because higher levels of DDGS are incorporated into pig diets. Relatively high level of poly-unsaturated fatty acids (PUFA) in DDGS may increase pork susceptibility to lipid oxidation and thus reduce pork shelf life. Antioxidants such as vitamin E may delay the onset of pork lipid oxidation when used as an ingredient in the diet. This experiment examined carcass characteristics, meat quality, shelf life, and color stability in pork from pigs (n = 150) fed five levels of a natural vitamin E (Nova-E) and one level of synthetic vitamin E. Natural vitamin E and synthetic vitamin E had no effect on carcass characteristics or meat quality. Increasing dietary natural vitamin E from 10 to 200 mg/kg decreased lipid oxidation. Lipid oxidation of pork chops and ground pork was similar between pigs fed 40 mg/kg and higher levels of natural vitamin E, indicating no additional benefits from supplementing beyond 40 mg/kg natural vitamin E. Supplementing 200 mg/kg synthetic vitamin E decreased pork lipid oxidation when compared to supplementing 10 mg/kg natural vitamin E. High levels of natural vitamin E or synthetic vitamin E, however, did not prevent discoloration of loin chops. These data indicate that natural vitamin E was effective to help reduce lipid oxidation and the effective minimal level of dietary supplementation appeared to be 40 mg/kg.     

食物中维生素A、叶酸和维生素E分析方法研究进展

对食物中 3种重要的维生素 :维生素A、叶酸和维生素E的常用分析方法进行了综述。指出了不同分析方法的适用范围以及各自的优缺点。着重介绍了高效液相色谱法在此 3种维生素分析中的应用。并提出了分析方法的发展趋势是高效液相色谱法 (包括正相高效液相色谱法、反相高效液相色谱法和非水反相高效液相色谱法 )、高效液相 -质谱法、气相色谱 -质谱法和离子色谱-质谱法等方法。     

Effect of dietary supplementation of vitamin E on characteristics of lamb meat packed under modified atmosphere

The effect of dietary vitamin E supplementation on modified-atmosphere packed lamb meat during storage was studied. Thirty-six weaned male Manchego breed lambs were fed diets supplemented with three different vitamin E concentrations (0, 250, 500 and 1000 mg/kg feed) for an average of 37 days, in the 13–26 kg live weight growth range. Slices of m. longissimus dorsi were packaged under modified atmosphere (70% O₂ and 30% CO₂), stored at 2 ± 1 °C in darkness for 14 and 28 days. Meat quality parameters after both storage periods were assessed. Dietary vitamin E supplementation significantly increased -tocopherol concentration in muscle. Initially, lipid oxidation (TBARS), meat colour and bacterial load were similar in all groups. Lipid and colour oxidation of meat increased significantly (P < 0.001) throughout storage. The increase was greater in non-supplemented lambs than in supplemented ones. The bacterial counts after 28 days of storage reached the limit for microbiological shelf life (7 log₁₀cfu/cm²). Dietary vitamin E supplementation increased the shelf life of meat packaged under modified atmosphere to 14 days. TBARS, pigment oxidation and bacterial load were inside the acceptable limit. The meat maintained its quality for 28 days of storage only when lambs were fed with the 1000 mg/kg dietary supplement, though the bacterial load was at the limit of acceptability.     

Effect of endogenous ascorbic acid oxidase activity and stability on vitamin C in carrots (Daucus carota subsp. sativus) during thermal treatment

The purpose of this research was to study the effect of endogenous ascorbic acid oxidase (AAO) on vitamin C in carrots (Daucus carota subsp. sativus), namely Nantes, Egmont Gold and baby carrots during thermal treatment. Enzyme-substrate reaction kinetics of AAO were described using Michaelis–Menten equation. The estimated K_m and V_max values of AAO ranged from 50.34 to 63.54 μM and 23.70 to 26.82 μmol/min, respectively. Nantes carrots had the lowest AAO activity. On the other hand, Egmont Gold had the highest V_max. AAO activity in all carrot cultivars was stable up to 50 °C and inactivated above 50 °C. Irreversible thermal inactivation of AAO followed first order kinetics (55–70 °C) and the estimated activation energy of the three carrot cultivars situated between 114.33 and 191.45 kJ/mol. Regarding vitamin C stability, thermal treatment at 60–70 °C has resulted in total conversion of l-AA to DHAA due to residual AAO activity; a complete AAO inactivation was found in 80 °C-treated carrots with high vitamin C retention predominantly in l-AA form, up to 90%. On average, the carrots had a total vitamin C content amounting from 368.24 to 379.87 μg/g dry matter and the Nantes carrots had the highest vitamin C content. The effectiveness of rapid inactivation of endogenous AAO via heating (>80 °C, 10 min) prior to matrix disruption gave protection to l-AA towards enzymatic oxidation, thus resulted in a higher vitamin C content and stability in carrots.     

海马酶法提取物的抗疲劳作用

为了解海马酶法提取物的抗疲劳作用，制备一次性运动疲劳模型小鼠和递增运动量疲劳模型小鼠，（后者的制备方法是：小鼠给予体重3％的负荷进行游泳，每天定时1次连续4d，第1天游泳时间30min，然后每天递增10min）。测定上述2种疲劳小鼠的血乳酸、血清尿素氮和后肢骨骼肌脂质过氧化程度。结果表明，海马酶解提取物（Enzymatic extracts of hippocampus，EEH）即可减少运动时乳酸、尿素氮和过氧化物的产生，又能促进运动后3者的清除；EEH的作用与机体的运动状态有关，随着运动量的增加和疲劳程度的加重，EEH的作用也增强。此外，对于正常小鼠，EEH可延长其在缺氧、寒冷以及缺氧合并寒冷条件下的生存时间，延长游泳时间。EEH的上述作用均呈明显的量效关系。在本试验条件下EEH具有明显的抗疲劳作用。