几种脱色剂对菜籽油脱色效果的研究

以菜籽油的色泽红值和叶绿素含量为考察指标,比较了凹凸棒土、活性白土、活性炭和双氧水4种脱色剂对菜籽油在中低温(40~80℃)下的脱色效果,同时考察了凹凸棒土与活性炭、活性白土与活性炭组成的复合吸附脱色剂对菜籽油的脱色效果。结果表明:活性炭在较低添加量条件下可以获得与凹凸棒土和活性白土较高添加量相当的脱色效果;活性白土-活性炭复合脱色效果优于凹凸棒土-活性炭,在添加量为2%时,80℃下可使菜籽油的叶绿素含量降低32. 5%、70℃下使菜籽油色泽红值降低30. 6%;双氧水对于去除菜籽油叶绿素和降低色泽红值效果明显,70℃下,0. 4%双氧水(10%)使菜籽油叶绿素含量降低9. 0%、0. 6%双氧水(10%)使菜籽油色泽红值降低25. 0%。活性白土-活性炭脱色和双氧水脱色后的菜籽油品质指标均达到国标四级菜籽油水平;就单位质量浓度脱色剂的脱色效果来说,双氧水的脱色效率更高。     

稻壳灰制取大豆油精炼中脱色剂的研究

稻壳灰经碱液处理后 ,再用硫酸活化以制取大豆油精炼中的脱色剂。探讨了碱液浓度、硫酸浓度、活化时间、活化温度等因素对脱色剂脱色能力的影响 ,并对脱色剂的性能作了研究。结果表明 ,碱液浓度最佳为 2mol/L ;活化过程可选择 5 %的硫酸 ,在 90℃下 ,活化 4h ,然后在不大于2 0 0℃的条件下干燥。产品的添加量较市售活性白土可减少一半 ,且脱色效果较好 ,适于连续操作。     

废混合吸附剂脱脂溶剂的选择及工艺的研究

混合吸附剂价格高，用于物理精炼或质量较差的油脂脱色，其废吸附剂中含油较高，采用不同的溶剂萃取，可以脱除其中的油脂和色素，实现中性油的回收或吸附剂的再生。研究表明，丙酮具有最好的脱脂效果，同时又能萃取出色素，适合于吸附剂再生；如果仅仅考虑回收中性油则正己烷是较理想的选择；废混合吸附剂比废白土含油高，且萃取更困难；确定废吸附剂脱脂后的残油率要考虑其来源。     

壳聚糖/活性白土糖用复合脱色剂的制备及其吸附特性研究

以活性白土和壳聚糖制备壳聚糖/活性白土复合脱色剂,糖汁脱色效果作为评价指标,分别考察制备过程中反应温度、反应时间、壳聚糖添加量、壳聚糖分子量等因素对其脱色效果的影响,获得最佳条件为:反应温度为60℃,反应时间为7 h,壳聚糖添加量为2.0 g,壳聚糖分子量为200万.该复合物的糖汁脱色率最高可达96.2％,明显优于活性...     

吸附法脱除芝麻油中苯并芘及脱色效果研究

研究不同吸附剂及用量脱除芝麻油中苯并芘(BaP)及脱色效果.结果表明:对于人为添加BaP含量为18.6μg/kg的芝麻油样品,在温度110℃、时间30 min、真空度0.095 Mpa及搅拌的吸附反应条件下,活性白土用量5％时,BaP极限残留量为13.13 μg/kg;普通活性炭用量2％时,BaP残留量为4.7 μg/kg;NORIT 8014-2活性炭、NORIT 8015-2活性炭用量分别为0.1％及0.2％时,BaP残留量分别为8.35μg/kg、8.44 μg/kg及1.03 μg/kg、1.62 μg/kg;普通活性炭、NORIT8014-2活性炭、NORIT 8015-2活性炭分别与活性白土组成的混合吸附剂配比及用量为0.3％+3％、0.05％+3％、0.05％+3％时,BaP残留量分别为5.51 μg/kg、4.6 μg/kg、6.39 μg/kg;混合吸附剂配比及用量分别为0.8％+3％、0.15％+3％、0.15％+3％时,BaP残留量分别为1.73 μg/kg、0.86 μg/kg、0.90 μg/kg.NORIT 8014-2、NORIT 8015-2活性炭对BaP的脱除效果明显好于普通活性炭,混合吸附剂脱除BaP和脱色的效果比单独活性炭及单独活性白土的效果好.     

废混合吸附剂脱脂溶剂的选择及工艺的研究

混合吸附剂价格高,用于物理精炼或质量较差的油脂脱色,其废吸附剂中含油较高,采用不同的溶剂萃取,可以脱除其中的油脂和色素,实现中性油的回收或吸附剂的再生。研究表明,丙酮具有最好的脱脂效果,同时又能萃取出色素,适合于吸附剂再生;如果仅仅考虑回收中性油则正己烷是较理想的选择;废混合吸附剂比废白土含油高,且萃取更困难;确定废吸附剂脱脂后的残油率要考虑其来源。     

吸附法精制劣变棕榈油的研究

研究了吸附法精制劣变棕榈油，分析了吸附温度、吸附剂用量、活性白土与活性炭的质量比、吸附时间对降低劣变棕榈油过氧化值的影响，较优的条件是吸附温度70℃，吸附剂用量5％，活性白土与活性炭的质量比为1．5：1，吸附时间40min，过氧化值从47．5meq／kg降到0．9meq／kg。     

脱色工艺中不同脱色剂对油茶籽油中苯并芘脱除效果的影响

研究了在优化的脱色条件下,脱色剂对油茶籽油中苯并芘的脱除作用。结果表明:活性炭对油茶籽油中苯并芘脱除效果显著,加入油质量3%的活性炭可以完全脱除样品中的苯并芘(苯并芘含量为7.12μg/kg);活性白土基本不具备脱除苯并芘的能力,但在活性炭中加入活性白土后,活性白土优先脱除油茶籽油中色素等杂质,为活性炭对苯并芘的脱除保留了吸附能力,使得活性炭对苯并芘的脱除效率提高,在3%活性白土的存在下,加入油质量0.3%的活性炭即可达到单独使用3%活性炭对苯并芘的脱除量,相当于将脱除苯并芘的能力提高10倍左右。     

活性炭—高效的糖液脱色剂

对活性炭的特点、制造、质量和使用性能进行了全面的介绍 ,用活性炭对碳酸法甘蔗糖厂的二碳饱充汁进行了化验室试验 ,并对试验结果作了初步的分析和讨论。     

改性大豆油硅胶吸附脱色工艺研究

研究了硅胶、活性白土、活性炭作为脱色剂对改性大豆油的脱色效果。从硅胶用量、脱色时间以及脱色温度方面系统考察了硅胶对改性大豆油脱色的最佳条件;此外,还考察了脱色后改性大豆油的运动黏度、酸值、倾点的变化情况。结果表明:相同条件下,硅胶脱色效果最好;在硅胶用量1.0%、脱色温度60℃、脱色时间3 h的条件下,以硅胶为脱色剂对改性大豆油进行吸附脱色,脱色率可达37.5%;脱色后改性大豆油运动黏度(40℃)由123.7 mm~2/s降至117.3 mm~2/s,运动黏度(100℃)由20.9 mm~2/s降至16.8 mm~2/s,倾点由34.3℃降至26.5℃,酸值(KOH)由9.9 mg/g降至9.0 mg/g。     

乙缩醛溶液的脱色研究

以乙缩醛生产过程中精馏塔塔底有色高沸物为研究对象,分别以粒状活性炭、硅藻土、活性白土和粉煤灰为脱色剂,考察了其脱色的可能性,发现活性炭对其脱色最有效。以脱色温度、活性炭用量、脱色时间和搅拌强度为实验因素,以脱色率为考察指标,分别用单因素实验和正交实验对乙缩醛溶液进行了脱色研究,最终确定乙缩醛溶液脱色的最佳条件为:活性炭用量20%,脱色温度20℃,脱色时间6h,脱色率为78.7%。     

活性炭静态吸附马氏珠母贝胰酶水解产物中氨基酸特性研究

采用胰酶酶解马氏珠母贝肉蛋白,研究了活性炭静态吸附前后酶解产物中氨基酸及各组分的变化情况。结果表明:在马氏珠母贝胰酶水解体系中,结合态和游离态芳香族氨基酸分别被吸附67.4%和42.3%,处于结合态的芳香族氨基酸更易于被活性炭吸附,并且活性炭吸附后,分子量较大组分的蛋白或多肽含量明显下降。     

氨基酸组成对谷氨酸结晶的影响

对不同工段谷氨酸发酵液及多次结晶母液的氨基酸含量进行了测定.结果表明,正常形成α型结晶和结晶异常-出现β型结晶的谷氨酸发酵液、超滤液和四效浓缩液中的氨基酸摩尔组分无显著性差异.脯氨酸极易掺人到α型晶体中.     

凹凸棒土与活性炭对水溶性染料的吸附研究

研究了凹凸棒土与活性炭对水溶性染料亚甲基蓝和弱酸艳蓝RAW的吸附作用，考察了各种因素对吸附效果的影响．结果表明：升高温度、增加pH值均有利于凹凸棒土对亚甲基蓝的吸附，不利于其对弱酸艳蓝RAW的吸附,温度升高，活性炭对2种染液的脱色率均有提高；酸性条件有利于活性炭对亚甲基蓝的吸附，而碱性条件有利于其对弱酸艳蓝RAW的吸附．达到同等处理效果，凹凸棒土用量明显少于活性炭,除活性染料外，凹凸棒土对其他染料的脱色性能均优于活性炭．     

A method for determination of fruit-derived ascorbic, tartaric, oxalic and malic acids, and its application to the study of ascorbic acid catabolism in grapevines

Background and Aims:  The majority of the acidity of a grapevine ( Vitis vinifera L.) berry is a result of the accumulation of l -tartaric (TA) and l -malic acids (MA). TA is synthesised from l -ascorbic acid (Asc, vitamin C), the metabolism of which is poorly characterised in grapevines. In a distinct pathway, oxalic acid (OA) is also formed from Asc degradation. The aim of this study was to develop a single method whereby the distribution of Asc and its catabolites from fruit and vegetative sources could be determined.
Methods and Results:  Effective recoveries of total Asc, TA, OA and MA were achieved with this extraction method, while chromatographic separation was accomplished with reversed-phase high-performance liquid chromatography (RP-HPLC). These results demonstrate that Asc and its catabolites TA and OA rapidly accumulate in immature berries, and that the Asc to dehydroascorbate ratio increases with berry maturity.
Conclusions:  A method for the simultaneous analysis of Asc, TA, OA and MA in fruits is provided; moreover, we have demonstrated its use to study their distribution in fruits, rachis, leaves and roots.
Significance of the Study:  This method enables accurate monitoring of the accumulation of Asc, permitting further research towards understanding acid metabolism during berry ripening.     

Meta-analysis to predict the effects of metabolizable amino acids on dairy cattle performance

Meta-analytic methods were used to determine statistical relationships between metabolizable AA supplies and milk protein yield, milk protein percentage, and milk yield in lactating dairy cows. Sixty-three research publications (258 treatment means) were identified through a search of published literature using 3 search engines and met the criteria for inclusion in this meta-analysis. The Cornell Net Carbohydrate and Protein System (CNCPS) version 6.5 was used to determine dietary nutrient parameters including metabolizable AA. Two approaches were used to analyze the data. First, mixed models were fitted to determine whether explanatory variables predicted responses. Each mixed model contained a global intercept, a random intercept for each experiment, and data were weighted by the inverse of the SEM squared. The second analysis approach used classical effect size meta-analytical evaluation of responses to treatment weighted by the inverse of the treatment variance and with a random effect of treatment nested within experiment. Regardless of the analytical approach, CNCPS-predicted metabolizable Met (g/d) was associated with milk protein percentage and yield. Milk yield was positively associated with CNCPS-predicted metabolizable His, Leu, Trp, Thr, and nonessential AA (g/d). Milk true protein yield was also associated with CNCPS-predicted metabolizable Leu (g/d). Predicted metabolizable Lysine (g/d) did not increase responses in production outcomes. However, mean metabolizable Lys supply was less than typically recommended and the change with treatment was minimal (157 vs. 162 g; 6.36 vs. 6.38% metabolizable protein). Experiments based solely on Lys or Met interventions were excluded from the study database. It is possible that the inclusion of these experiments may have provided additional insight into the effect of these AA on responses. This meta-analysis supports other research indicating a positive effect of Met and His as co-limiting AA in dairy cows and suggests Leu, Trp, and Thr be given greater consideration in future research.     

反胶束萃取氨基酸研究进展

该文综述反胶柬萃取氨基酸研究进展,包括萃取机理,应用研究进展;并展望反胶束技术萃取氨基酸良好工业化应用前景。     

The effect of feeding canola meal on concentrations of plasma amino acids

An initial meta-analysis on isonitrogenous experiments where a protein source was replaced by canola meal (CM) showed that CM feeding increased yields of milk and milk protein and apparent N efficiency. The objective of the current study was to determine if these responses were related to increased changes in plasma AA concentrations. Although only half of the experiments of the initial meta-analysis reported concentrations of plasma AA and could be used in the current meta-analysis, lactational responses to CM feeding were similar to those reported previously. In the current meta-analysis, CM feeding increased plasma concentrations of total AA, total essential AA (EAA) and all individual EAA, but decreased concentrations of blood and milk urea-N. The current meta-analysis suggests that CM feeding increased the absorption of EAA, which would be responsible for the increased milk protein secretion and the increased apparent N efficiency.     

氨基酸口服营养品的现状与展望

氨基酸的功能一直为人们所关注,可广泛应用于医药、食品、农牧渔业、农药、化妆品、保健品等领域。氨基酸向来是国际医药市场的大宗产品。近年来国外出现了一种新趋向,即原本作为药用的氨基酸开始向保健品方向发展。简要综述了发达国家如美国、日本以及国内氨基酸口服保健品的现状,并初步探讨我国氨基酸保健品市场进一步的发展方向。