微生物法测定发酵食品中维生素B12含量的研究

为明确发酵食品中维生素B12的含量及分布,利用微生物法对大豆发酵食品（3种类型腐乳、韩国大酱、纳豆、豆汁）及奶酪中维生素B12的含量进行了测定。结果表明,在3种腐乳中,臭腐乳维生素B12含量最高,达到（3.57±1.08） μg/100 g,红腐乳和白腐乳分别为（0.48±0.21） μg/100 g和（0.41±0.16） μg/100 g;除腐乳外,纳豆（0.50 μg/100 g、0.20 μg/100 g）、韩国大酱（0.97 μg/100 g、0.10 μg/100 g）、豆汁（熟）（0.52 μg/100 g）的维生素B12含量均低于臭腐乳。虽然个别奶酪样品中维生素B12含量最高可达1.54 μg/100 g,但其总体维生素B12的分布及含量也均低于臭腐乳。     

IFP微孔板试剂盒检测配方乳粉中维生素B12方法探讨

研究如何提高微生物方法测定维生素B12的准确性和稳定性.对微生物法测定维生素B12过程的关键控制点、主要影响因素进行探讨分析.本文采用IFP微孔板试剂盒检测配方乳粉中维生素B12与传统方法比较操作方法简便、重复性高、结果准确.     

特殊食品中3种B族维生素检测方法的研究进展

随着人们对健康和营养的关注,特殊食品的种类越来越多.叶酸、生物素和维生素B12是特殊食品中3种重要的营养添加剂,其准确测定对于特殊食品的质量控制具有重要意义.文章对特殊食品中叶酸、生物素和维生素B12的生理作用以及检测方法进行论述,以期为开展特殊食品中这3种B族维生素的测定研究提供参考.     

微生物法测定多种维生素片中的生物素含量

目的利用微生物法测定多种维生素片中生物素的含量。方法在GB 5413.19-2010分析方法的基础上,通过将乳酸杆菌培养基改成MRS肉汤培养基来制备菌悬液,样品经过65℃~70℃水浴超声提取,在630nm波长下用酶标仪测定培养液吸光度,对生物素含量进行定量检测。与国标法进行标准曲线、精密度、准确度对比试验,以及对新建立的方法进行加标回收试验。结果生物素浓度在0.01~0.1 ng/m L范围内与吸光度呈现良好的二次曲线关系,相关系数r20.999,精密度和准确度良好。在80%、100%、120%添加水平下,生物素的回收率分别为99.8%、96.1%、97.2%。结论方法操作简单、灵敏度高、处理量大,适合生产企业的多种维生素片的大批量质量控制和检测。     

微生物法测定肠内营养粉剂中微量维生素 B12的含量

目的建立微生物法测定肠内营养粉剂中微量维生素B_(12)的含量。方法以莱士曼氏乳酸杆菌为实验菌,在测定用培养基中供给除维生素B_(12)以外的所有营养成分,(36±1)℃培养19~20 h,采用比浊法测定。结果维生素B_(12)在0.001~0.010 ng/mL浓度范围内线性关系良好,肠内营养粉剂中维生素B_(12)的含量为2.9μg/100 g。结论该方法检测结果准确、可靠,适用于肠内营养粉剂中微量维生素B_(12)的含量测定。     

微生物法测定腐乳中维生素B12含量的研究

该文主要研究菌悬液放置时间与培养菌液对菌落总数的影响,并将含维生素B_(12)的培养菌液用于测定4种腐乳(红腐乳、白腐乳、青腐乳和玫瑰腐乳)中维生素B_(12)的含量。结果表明,最佳的菌悬液放置时间为1 h,不同厂家生产的同一类型的腐乳维生素B_(12)含量存在显著差异。4种腐乳中,青腐乳发酵的最为彻底,并具有最高含量的维生素B_(12),其含量是红腐乳和白腐乳的10倍多,高达7.01μg/100 g。其次是玫瑰腐乳,玫瑰成分经过发酵后会产生较多的营养成分,维生素B_(12)的含量也较多,达3.84μg/100 g。红腐乳和白腐乳中维生素B_(12)的含量较低,分别为0.63μg/100 g和0.49μg/100 g。     

SPR技术对奶粉中维生素B12检测方法的建立

目的 利用表面等离子共振(surface plasmon resonance, SPR)技术, 建立快速定量测定牛奶中维生素B12的方法。方法 将钴胺素共价偶联到表面等离子共振芯片CM5表面, 并对竞争结合的维生素B12结合蛋白的结合浓度及芯片的再生条件进行优化, 检测芯片的稳定性。在无抗生素牛奶中添加系列质量浓度的维生素B12, 利用免疫竞争抑制原理构建标准曲线, 并对市售10个奶粉样品进行检测。结果 制备的芯片稳定, 50个循环相对标准偏差(relative standard deviation, RSD)小于10%。日间批内同一样品差异为0.54%, 该方法的检测限为0.006 μg/100 g, 回收率为92.1%~104.1%。测得的10个牛奶产品中维生素B12含量与对应商品标签值全部在标准规定的范围内。结论 所建立的方法可以在6 h内完成样品的前处理和检测, 是一种简便、快捷的定量检测方法。     

维生素B12检测方法研究进展

维生素B12作为一种生物活性物质,在贫血、神经系统疾病、出生缺陷、评价指标、营养强化等方面发挥重要的作用。由于维生素B12结构复杂,且含量很低,提升其检测手段具有重要的实际意义。该文对国内外维生素B12检测方法进行综述,主要包括液相色谱法,微生物方法,酶联免疫吸附测定法,原子吸收光谱法,电感耦合等离子测定法,电化学传感器方法,表面离子共振检测,荧光分子探针方法等,涉及光谱学、电化学、免疫学、色谱和微生物等学科。重点对维生素B12检测方法从技术原理、操作特点、分析效果以及应用范围作简单述评,最后对维生素B12检测技术手段的发展趋势进行讨论和展望。     

微生物法测定乳粉中维生素B12的应用和探讨

国家标准GB/T 5413.14-1997等同采用AOAC 986.23微生物法,是目前用于维生素B12测定的主要方法和仲裁方法.但该法操作复杂,影响结果的因素很多,对检验人员和实验室的要求较高.现将测定中关键步骤,主要影响因素,容易出现的问题等进行探讨,包括提取方法、标线制备、防止污染、菌种保存、注意事项及操作一致性的必要性等诸多方面,可作为对该方法的说明和补充.     

Effects of dietary supplements of folic acid and vitamin B12 on metabolism of dairy cows in early lactation

The present experiment was undertaken to determine the effects of dietary supplements of folic acid and vitamin B₁₂ given from 3 wk before to 8 wk after calving on lactational performance and metabolism of 24 multiparous Holstein cows assigned to 6 blocks of 4 cows each according to their previous milk production. Supplementary folic acid at 0 or 2.6 g/d and vitamin B₁₂ at 0 or 0.5 g/d were used in a 2 × 2 factorial arrangement. Supplementary folic acid increased milk production from 38.0 ± 0.9 to 41.4 ± 1.0 kg/d and milk crude protein yield from 1.17 ± 0.02 to 1.25 ± 0.03 kg/d. It also increased plasma Gly, Ser, Thr, and total sulfur AA, decreased Asp, and tended to increase plasma Met. Supplementary B₁₂ decreased milk urea N, plasma Ile, and Leu and tended to decrease Val but increased homocysteine, Cys, and total sulfur AA. Liver concentration of phospholipids was higher in cows fed supplementary B₁₂. Plasma and liver concentrations of folates and B₁₂ were increased by their respective supplements, but the increase in plasma folates and plasma and liver B₁₂ was smaller for cows fed the 2 vitamins together. In cows fed folic acid supplements, supplementary B₁₂ increased plasma glucose and alanine, tended to decrease plasma biotin, and decreased K_m of the methylmalonyl-coenzyme A mutase in hepatic tissues following addition of deoxyadenosylcobalamin, whereas it had no effect when cows were not fed folic acid supplements. There was no treatment effect on plasma nonesterified fatty acids as well as specific activity and gene expression of Met synthase and methylmalonyl-coenzyme A mutase in the liver. Ingestion of folic acid supplements by cows fed no supplementary B₁₂ increased total lipid and triacylglycerols in liver, whereas these supplements had no effect in cows supplemented with B₁₂. The increases in milk and milk protein yields due to folic acid supplements did not seem to be dependent on the vitamin B₁₂ supply. However, when vitamin B₁₂ was given in combination with folic acid, utilization of the 2 vitamins seems to be increased, probably more so in extrahepatic tissues. Metabolic efficiency seems also to be improved as suggested by similar lactational performance and dry matter intake for cows fed supplementary folic acid but increased plasma glucose and decreased hepatic lipids in cows fed folic acid and vitamin B₁₂ together.     

Effects of intramuscular injections of vitamin B12 on lactation performance of dairy cows fed dietary supplements of folic acid and rumen-protected methionine

The experiment was undertaken to determine the effects of i.m. injections of vitamin B(12) on lactational performance of primiparous dairy cows fed dietary supplements of folic acid and rumen-protected methionine from 4 to 18 wk of lactation. Fourteen primiparous Holstein cows were assigned to 7 blocks of 2 cows each, according to milk production during the third week of lactation. All cows were fed a basal diet supplemented daily with rumen-protected methionine (18 g of supplement, to bring the estimated supply of methionine to 2.2% of metabolizable protein) plus folic acid (4 mg per kg of BW). Within each block, the cows received a weekly i.m. injection (2 mL) of saline or 10 mg of vitamin B(12). Milk production was recorded daily. Milk and blood were sampled every 2 wk. Supplementary vitamin B(12) increased energy-corrected milk from 25.8 to 29.0 (SE 1.6) kg/d, as well as milk yields of solids [3.52 to 3.90 (SE 0.22) kg/d], fat [0.87 to 1.01 (SE 0.06) kg/d], and lactose [1.48 to 1.64 (SE 0.11) kg/d]. Supplementation also increased concentrations and amounts of vitamin B(12) secreted in milk but had no significant effect on dry matter intake and concentrations and amounts of folates in milk. Packed cell volume, blood hemoglobin, and serum vitamin B(12) were increased by supplementary vitamin B(12), whereas serum methylmalonic acid was decreased. Serum concentrations of sulfur amino acids were unchanged by treatment. These findings support the hypothesis that, in early lactation, supply of vitamin B(12) was not optimal and limited the lactation performance of the cows.     

谷氨酸生产中生物素含量的检测

微生物检测法是利用营养缺陷型菌株细胞的生长、繁殖与环境中某一限制性营养因子含量之间存在关联性而建立起来的一种生物检测方法.微生物法可以免去繁琐的样品预处理步骤,适合于生物素含量测定.在生物素浓度为0～0.8μg/L的范围内可以获得重复性较好的线性关系.利用该方法,分析了玉米浆、糖蜜、淀粉水解糖液中生物素的含量,分别为248.18μg/kg,1790.53μg/kg和1.25μg/L.     

Effects of folic acid and vitamin B12 supplementation on culling rate,diseases, and reproduction in commercial dairy herds

This study was undertaken to determine the effect of a combined folic acid and vitamin B₁₂ supplement given in early lactation on culling rate, metabolic disorders and other diseases, and reproduction in commercial dairy herds. A total of 805 cows (271 primiparous and 534 multiparous cows) in 15 commercial dairy herds were involved. Every 2 mo from February to December 2010 and within each herd, cows were assigned according to parity, previous 305-d milk production, and calving interval to 5 mL of either (1) saline 0.9% NaCl (control group) or (2) 320 mg of folic acid + 10 mg of vitamin B₁₂ (vitamin group). Treatments were administered weekly by intramuscular injections starting 3 wk before the expected calving date until 8 wk after parturition. A total of 221 cows were culled before the next dry period. Culling rate was not affected by treatment and was 27.5%; culling rate was greater for multiparous (32.2%) than for primiparous cows (18.8%). Within the first 60 d in milk (DIM), 47 cows were culled, representing 21.3% of total culling, and no treatment effect was noted. Ketosis incidence based on a threshold ≥100 µmol/L of β-hydroxybutyrate in milk was 38.3 ± 2.9% for the vitamin group and 41.8 ± 3.0% for the control group and was not affected by treatment. The combined supplement of folic acid and vitamin B₁₂ did not decrease incidence of retained placenta, displaced abomasum, milk fever, metritis, or mastitis. However, the incidence of dystocia decreased by 50% in multiparous cows receiving the vitamin supplement, although no effect was observed in primiparous cows. The first breeding postpartum for multiparous cows occurred 3.8 d earlier with the vitamin supplement compared with controls, whereas no treatment effect was seen for primiparous cows. Days open, first- and second-breeding conception rates, number of breedings per conception, and percentage of cows pregnant at 150 DIM were not affected by treatment. The reduced percentage of dystocia combined with the earlier DIM at first breeding for multiparous cows receiving the combined supplementation in folic acid and vitamin B₁₂ indicates that the vitamin supplement had a positive effect in older cows.     

培养基质量控制对维生素B12含量测定的影响

目的 GB 5413.14-2010微生物法检测维生素B₁₂中培养基的质量和配方直接影响莱士曼氏乳杆菌在整个检测过程中的活化,接种和测定。方法 为解决这一问题,本文通过比较不同配方菌株活化培养基和种子液制备肉汤培养基及不同品牌测定培养基对维生素B₁₂ 结果测定的影响。利用莱士曼氏乳杆菌对维生素B₁₂的特异性和灵敏性,定量测定质控样品中维生素B₁₂的含量,并通过质量控制措施对测定结果进行分析评价。结果 方案设计中A2种活化菌株方式所用培养基和B1品牌的维生素B₁₂测定培养基得到的拟合曲线线性更好,质控结果组间差异也更小。结论 表明培养基质量控制对维生素B₁₂检测的准确度和稳定性极为重要。     

Intake of vitamin B6, folate,and vitamin B12 and risk of coronary heart disease: a systematic review and dose-response meta-analysis of prospective cohort studies

Abstract

The objective of this study was to quantify the association of B-vitamins intake with the future risk of coronary heart disease (CHD). A systematic search was performed with the use of PubMed and Scopus from inception to April 30, 2018. Prospective cohort studies evaluating the association of intake of folate, vitamin B6, and vitamin B12 with risk of CHD in the general population were included. A random-effects meta-analysis was performed. Eleven prospective cohort studies (total n?=?369,746) with 5133 cases of CHD were included in the analyses. The relative risks were: 0.79 (95%CI: 0.69, 0.89; I²?=?67%) for a 250?µg/d increment in folate intake; 0.87 (95%CI: 0.78, 0.96; I²?=?80%) for a 0.5?mg/d increment in vitamin B6 intake; and 0.97 (95%CI: 0.80, 1.14: I²?=?67%) for a 3?µg/d increment in vitamin B12 intake. The results did not change materially when the analyses were restricted only to dietary vitamins intake. A nonlinear dose-response meta-analysis demonstrated a linear inverse association between folate and vitamin B6 intake and risk of CHD. In conclusion, higher intake of folate and vitamin B6 is associated with a lower risk of CHD in the general population.     

高效液相色谱-串联质谱法同时测定复合维生素片中的叶酸和生物素

目的建立高效液相色谱-串联质谱法同时定性和定量分析复合维生素片中叶酸和生物素的方法。方法样品用水溶液溶解,经Eclipse C18色谱柱(2.1 mm×100 mm,1.8μm)分离,流动相为0.1%甲酸溶液和乙腈梯度洗脱,流速0.2 ml/min,采用电喷雾离子源正离子模式,多反应监测(MRM)进行检测。结果叶酸和生物素在5 min内得到较好的分离。叶酸和生物素的线性范围分别为42~523和47~583 ng/ml,线性回归方程分别为y=1157.63x-6698.38(r~2=0.999 9)和y=207.93x-3052.26(r~2=0.998 2),低、中、高3个添加水平的回收率分别为99.9%~108.7%和90.1%~94.5%,相对标准偏差(RSD)均为1.0%(n=6),检出限分别为0.33和0.08μg/g。结论高效液相色谱-串联质谱法可靠、灵敏、准确,可用于复合维生素片中叶酸和生物素同时定性和定量分析。