一种连续分离纯化酪蛋白磷酸肽的新工艺

为建立一条制备酪蛋白磷酸肽(CPPs)的新工艺路线。采用酶解与超滤耦联技术初步分离制备酪蛋白生物活性肽,然后通过树脂层析将酪蛋白生物活性肽中的酪蛋白磷酸肽和非磷酸肽分离。选用碱性蛋白酶Alcalase在切向流酶膜反应器中(膜截留分子质量10kD)连续酶解3h、酶解温度50℃、pH8.5。重点研究大孔弱碱性阴离子交换树脂D303对酪蛋白生物活性肽的分离纯化工艺,并采用单因素试验优化CPPs的分离纯化工艺参数,确定D303树脂的较佳动态吸附解吸条件：上样流速1BV/h、上样量100mL、洗脱温度45℃、洗脱酸浓度0.15mol/L HCl,获得磷酸肽N/P比为7.21,P洗脱得率为93.11%。     

响应面试验优化新疆野生准噶尔山楂残渣中多糖纯化工艺

为纯化准噶尔山楂残渣中的粗多糖,通过动态吸附和洗脱实验从7 种大孔吸附树脂中选出两种最优树脂NKA-9和D101,按一定比例进行混合实验。在单因素试验基础上,利用响应面法确定最佳纯化条件：NKA-9与D101树脂最佳混合质量比为2∶3;最佳吸附工艺条件为上样液流速3.75 mL/min、上样液质量浓度1.32 g/L、树脂径高比1∶13,此条件下多糖的吸附率为60.75%;最佳洗脱工艺条件为洗脱液浓度0.27 mol/L、洗脱液流速3.5 mL/min、洗脱液用量7 BV,此条件下多糖的洗脱率为84.22%。样品中多糖含量由原来的5.06%上升至21.13%。     

优化大孔树脂提取分离苋菜红色素的工艺

采用正交设计实验筛选AB-8大孔树脂纯化苋菜红色素的最佳工艺条件。其最佳工艺为：上样pH值为3、吸附流速1.2 mL/min、洗脱剂浓度为15%乙醇溶液、洗脱流速0.9 mL/min。经过AB-8大孔树脂提纯后,提高了苋菜红色素的品质。     

微生物发酵液中ε-聚赖氨酸的分离提纯

筛选适用于分离提纯微生物发酵液中ε- 聚赖氨酸的树脂并确定其工艺条件。以ε- 聚赖氨酸吸附量和回收率为考察指标,采用静态吸附法选择适合的树脂,采用动态吸附法确定提取工艺。结果表明,弱酸型阳离子交换树脂HD-2 对ε- 聚赖氨酸具有良好的吸附分离性能。其动态分离提纯工艺条件为：层析柱为22mm × 300mm 时,上样流速为3mL/min;以0.1mol/L 的HCl 为洗脱液,洗脱流速为3mL/min。此工艺条件下,ε- 聚赖氨酸的回收率为92.0%。     

大孔树脂吸附分离S-腺苷甲硫氨酸的研究

采用大孔树脂吸附法对S-腺苷甲硫氨酸(S-adenosylmethionine,SAM)纯化工艺进行研究。通过考察上柱流速、浓度、p H等因素对S-腺苷甲硫氨酸动态吸附的泄露曲线和树脂饱和吸附量影响,确定S-腺苷甲硫氨酸树脂动态吸附的最佳工艺条件为:上柱流速3.6 m L/min,进样料液浓度5.0 g/L,初始p H=5.0。用0.5 mol/L硫酸以流速3.6 m L/min洗脱吸附饱和树脂,产品得率为92.57%。树脂重复使用5次后其对SAM的吸附量和解吸率分别下降了13.68 mg/g和6.76%。     

微生物发酵液中ε-聚赖氨酸的分离提纯

筛选适用于分离提纯微生物发酵液中ε-聚赖氨酸的树脂并确定其工艺条件。以ε-聚赖氨酸吸附量和回收率为考察指标,采用静态吸附法选择适合的树脂,采用动态吸附法确定提取工艺。结果表明,弱酸型阳离子交换树脂HD-2对ε-聚赖氨酸具有良好的吸附分离性能。其动态分离提纯工艺条件为:层析柱为22mm×300mm时,上样流速为3mL/min;以0.1mol/L的HCl为洗脱液,洗脱流速为3mL/min。此工艺条件下,ε-聚赖氨酸的回收率为92.0%。     

响应面法优化黑果枸杞酒渣多糖精制工艺

在单因素试验基础上,利用响应面法的BBD组合设计,对大孔树脂精制黑果枸杞酒渣多糖工艺参数进行优化分析。结果显示：AB-8树脂具有较好的吸附能力,最佳吸附条件为上样液pH9、质量浓度1g/L、流速1mL/min、树脂径高比1:15,在此条件下吸附率为92.87%;最佳解吸附条件为洗脱液NaCl溶液pH9、浓度0.25mol/L、流速1mL/min、用量5BV。将洗脱液浓缩,真空干燥即得黑果枸杞酒渣精制多糖,多糖含量为67.13%。     

树脂柱层析法分离纯化籽瓜中L-瓜氨酸

目的:研究适合分离纯化籽瓜L-瓜氨酸的树脂柱层析方法。方法:选择001×7、D001和D061三种阳离子交换树脂进行L-瓜氨酸静态吸附解析和动态平衡实验,优化分离提纯籽瓜L-瓜氨酸工艺。通过考察温度、p H、浓度、吸附穿透曲线及洗脱液浓度、流速因素,进一步研究001×7树脂层析柱分离纯化籽瓜L-瓜氨酸的条件。测定三种不同极性大孔吸附树脂和活性炭对籽瓜提取液的脱色率和吸附率,优化脱色工艺。结果:分离提纯籽瓜L-瓜氨酸工艺用001×7型阳离子交换树脂较适合,最佳工艺条件:上柱温度为40~50℃,上柱液的p H为3,洗脱液选择0.5 mol/L的氨水,洗脱流速为0.5 m L/min,洗脱液的用量为6倍树脂体积。脱色工艺使用HZ-801大孔吸附树脂较合适,脱色精制后可得到纯度为96.6%的L-瓜氨酸产品。结论:001×7型阳离子交换树脂层析柱和HZ-801大孔吸附树脂相结合,可以有效分离纯化籽瓜中的L-瓜氨酸,对充分利用籽瓜资源和改变我国L-瓜氨酸成本较高现状具有十分重要的意义。     

牦牛与奶牛酪蛋白制备CPPs的酶工艺优化及其离子交换纯化研究

优化了以牦牛酪蛋白与奶牛酪蛋白为原料酶法制备酪蛋白磷酸肽（CPPs）的工艺条件，并评估了离子交换对CPPs粗制品的纯化效果。结果表明，牦牛酪蛋白与奶牛酪蛋白的产率最优化条件以及氮磷比r（N／P）最优化的酶解工艺条件均基本一致，产率最大的胰蛋白酶酶解工艺条件为：底物浓度13．1％，酶解反应时间104min，酶底物浓度比0．9％；r（N／P）最优（小）的酶解工艺条件为：底物浓度7．6％，酶解反应时间155min，酶底物浓度比1．2％。牦牛及奶牛CPPs粗制品经过阴离子交换树脂纯化后，所获得的精制CPPs其，（N／P）均明显降低，对于CPPs的产率最优样品其，（N／P）由原来的12．2～12．4降低到6．3～6．9；对于r（N／P）最优样品，其r（N／P）由原来的9．90～0．95进一步降低至5．6～5．8。研究表明：无论以产率或制品质量为优化指标，牦牛与奶牛酪蛋白的酶解工艺优化条件基本一致。而且利用阴离子交换树脂处理可以有效地降低CPPs粗制品的r（N／P）、提高制品的质量。     

酪蛋白磷酸肽制备工艺参数的优化研究

对Alcalase碱性蛋白酶水解酪蛋白制备酪蛋白磷酸肽(CPPs)的工艺参数进行优化。根据单因素实验和Box-Behnken中心组合实验设计原理,以CPPs得率为指标,采用四因素三水平响应面法进行分析。结果表明:制备CPPs优化工艺条件为温度53.58℃,底物质量浓度65 g/L,酶底物比0.85∶100(质量比),p H值为7.57,在此条件下CPPs的得率最大为16.11%(质量分数)。     

大豆植酸分离方法对测定结果的影响

探讨了大豆植酸的浸提、离心和离子交换条件对其测定结果的影响。大豆经磨粉、过筛后 ,用 0 3 5mol/LHCl 0 7mol/LNa2 SO4溶液能充分提取出大豆的植酸 ;沸水浴后40 0 0r/min离心 10min可除去蛋白质 ;阴离子交换时 ,依次用 15mL蒸馏水、15mL 0 0 5mol/LNaCl淋洗 ,而后用 2 0mL 0 7mol/LNaCl以 1 0mL/min的速度洗脱 ,洗脱液的植酸加标回收率达到 98%以上 ;4个大豆样品中植酸测定结果的相对标准偏差分别为 1 2 3 %、4 0 5 %、1 5 3 %和 1 83 %。     

Preparation of casein phosphopeptides using a novel continuous process of combining an enzymatic membrane reactor with anion-exchange chromatography

A novel process for continuous preparation of casein phosphopeptides (CPPs) was developed using an enzymatic membrane reactor (EMR) and anion-exchange chromatography (AEC). Alcalase was selected to hydrolyse casein (with an initial concentration of 6% (w/w)) at pH 8.5 and temperature 50 °C in an enzymatic membrane reactor. CPPs were then separated from the enzymatic hydrolysates through a weakly basic macroporous anion-exchanger. The yields of CPPs and phosphorus from casein were 8.11%, 15.66% and 21.41%, and 19.10%, 52.70% and 90.01% for EMR fitted with 3 kDa, 5 kDa and 10 kDa membranes, respectively. The yield and quality of CPPs improved with increase in the nominal molecular weight cut-off (NMWCO) of the membrane. However, use of a high NMWCO membrane resulted in substantial enzyme leakage in the permeate.     

Short communication: Effect of sampling time relative to the first daily feeding on interpretation of serum fatty acid and β-hydroxybutyrate concentrations in dairy cattle

Serum nonesterified fatty acid (NEFA) and β-hydroxybutyrate (BHBA) concentrations are used to evaluate energy status in peripartum dairy cows. Blood samples from 37 cows in the week before parturition and 47 cows in the first week after parturition from 3 dairy herds were taken 1 h before the first feeding (−1 h) as well as 4 and 10 h after the first feeding. Nonesterified fatty acid concentrations were measured in samples from cows before calving and BHBA was measured in samples from lactating cows. Mean NEFA concentrations in the prepartum cows were significantly higher at −1 h (0.20 mmol/L) than at 4 h (0.14 mmol/L), but were not different between 4 and 10 h (0.17 mmol/L). Using a cutpoint of NEFA ≥0.4 mmol/L, 32% of cows had high concentrations at −1 h compared with 16% of the same cows at 4 and 10 h. There were no differences in mean BHBA between −1 h (646 μmol/L) and 4 h (596 μmol/L), but mean BHBA was higher at 10 h (711 μmol/L) than at −1 h. Using a cutpoint of BHBA ≥1,400 μmol/L, there were no differences in the proportions of high BHBA, which were 9, 11, and 13% of cows at −1, 4, and 10 h, respectively. Prandial effects on serum NEFA may affect interpretation of this analyte. In order not to misclassify cows when assessing energy status, samples for NEFA must at least be taken at a consistent time relative to feeding within a given herd. When sampling cows to monitor elements of energy metabolism in the prepartum period, there was twice the probability of detecting animals with NEFA values ≥0.4 mmol/L if they were sampled 1 h before the first feed delivery compared with sampling the same cows 4 or 10 h after feeding.     

Production of Caseinophosphopeptides from Na-Caseinates Prepared from the Milk of Several Species by a Proteinase of Lactobacillus helveticus PR4

The aim of this work was to produce caseinophosphopeptides (CPPs) from Na-caseinates prepared from the milk of six species (bovine, sheep, goat, pig, buffalo, human) hydrolyzed by a partially purified proteinase from Lactobacillus helveticus PR4 and to characterize the CPP preparations by RP-FPLC (reversed-phase fast-protein liquid chromatography) and for calcium solubilizing/binding activity. The yield of CPPs ranged from 0.60 to 1.86% of the original proteins. The calcium-solubilizing activity varied from 2.5 (human CPPs) to 11.4 (buffalo CPPs) mg Ca²⁺ mg^-1 CPP. Moreover, minor differences in calcium-binding ability between the CPP from different species were observed. This work showed that CPPs with different calcium-solubilizing activity can be produced from various Na-caseinates by a Lb. helveticus proteinase. Milks having casein-fractions with similar amino acid sequences (e.g., sheep and goat), showed CPPs with the same activity. The data generated in this study show the potential of different caseins to yield CPPs and may help in the selection of milk for the production of functional foods enriched in CPPs.     

蜂胶中CAPE对HGF诱导的HepG2细胞侵袭和迁移能力的抑制作用

目的:探讨咖啡酸苯乙酯(phenethyl caffeate,CAPE)对肝细胞生长因子(hepatocyte growth factor,HGF)诱导的人肝癌细胞系(Hep G2细胞)侵袭和迁移的抑制作用及机制。方法:将实验分为对照组(HGF=0 ng/m L;CAPE=0μmol/L)、诱导组(HGF=20 ng/m L;CAPE=0μmol/L)和荷药组(HGF=20 ng/m L;CAPE分别为2.5、5.0、7.5、10.0μmol/L),测定细胞黏附率,Transwell小室模拟细胞侵袭和迁移能力以及划痕实验测定细胞迁移率,蛋白免疫印迹(Western blot)法检测ELMO1、MAP4K4和FNDC3B表达。结果:与对照组比较,诱导组表现出显著的促进细胞黏附和迁移作用,荷药组中表现出对HGF诱导的细胞黏附和迁移具有显著的抑制作用(P0.05)。Transwell小室实验结果表明CAPE对HGF诱导的Hep G2细胞侵袭和迁移作用有抑制作用。Western blot结果显示,诱导组和对照组相比ELMO1和MAP4K4表达显著上调,荷药组和诱导组相比ELMO1和MAP4K4表达显著下调(P0.05);诱导组表达FNDC3B较对照组显著下降(P0.05),荷药组FNDC3B表达量较诱导组增加,但结果不显著(P0.05)。结论:CAPE能够抑制HGF诱导的Hep G2细胞的黏附、侵袭和迁移。CAPE通过上调FNDC3B和下调ELMO1、MAP4KE的表达,抑制Hep G2细胞的侵袭和迁移能力。     

电化学分析法快速测定烧烤类食品中的苯并(a)芘

基于苯并(a)芘(benzo(a)pyrene,BaP)的电化学氧化还原特征,建立一种快速测定烧烤类食品中BaP含量的电化学分析方法,优化测定条件为乙腈-水(1∶3,V/V)作为溶剂、电解质LiClO_4浓度0.15 mol/L、硫酸浓度0.1 mol/L、富集时间10 min,在此条件下,BaP的氧化峰电流随其浓度的增大而增大,而且浓度在0~100 nmol/L范围内呈线性关系,检测限为0.187 nmol/L(R_(SN)=3)。该方法的稳定性和重复性较好,检测时间短,利用该法对烤羊肉串样品中的BaP进行检测,回收率为96.67%~101.56%,检测结果与高效液相色谱法基本一致,可用于烧烤类食品中BaP的快速检测。     

氯化钠刺激对保加利亚乳杆菌生长及质膜流动性的影响

目的:研究NaCl刺激对保加利亚乳杆菌ATCC11842生长的影响,分析NaCl刺激下此菌细胞膜流动性和质膜脂肪酸组成的变化。方法:经不同浓度NaCl处理后,用荧光探针1,6-二苯基-1,3,5,-己三烯(DPH)研究细胞膜流动性的改变;用气相色谱法测定NaCl刺激下细胞膜脂肪酸组成的改变。结果:保加利亚乳杆菌能耐受的最高NaCl浓度为1.0mol/L。确定了在保加利亚乳杆菌中DPH孵育时间(60min)和温度(35℃)条件。当NaCl浓度为0.4mol/L时,此菌株中主要的脂肪酸为C16:0和C18:1;随着NaCl浓度增加,饱和脂肪酸/不饱和脂肪酸比率(SFA/UFA)从原来的0.57增加到0.78;同时,保加利亚乳杆菌存活率逐渐降低。结论:当NaCl浓度从0.2mol/L增加到0.8mol/L时,随着荧光偏振值和微黏度的增加,细胞质膜流动性减小,并且膜中饱和脂肪酸比率增加。     

蔗渣膳食纤维化学结构的研究(Ⅰ)──细胞壁物质(膳食纤维)的分离与分级

蔗渣含88．3％（干基）的膳食纤维，是一种良好的膳食纤维新资源。本文利用简化的CNDF法从蔗渣中提取出纯净的细胞壁物质（膳食纤维），分析其单糖组成为4．08％Ara，36．54％Xy1，31．68％Glc和3．29％UA。通过80℃H2O，NaClO2—HOAc，1mol／LNaOH和4mol／LNaOH4种溶剂将细胞壁物质分级成7种聚合物组分，并分析它们的单糖组成。     

反相高效液相色谱法测定草莓中的维生素C

报道了测定草莓中维生素C的反相高效液相色谱法。样品中的维生索C在zorbax ODs（5μm）反相色谱柱上分离、以0．025mol/LKH2PO4-甲醇（70:30）为流动相洗脱、用紫外检测法检测（λ=254 nm）。维生素C在2．5min内得到了良好的分离,检测范围为025mg/L。用于实际样品的分析,效果良好。