牛奶内酯豆腐的研制

以大豆和牛奶为原料,以葡萄糖酸-δ-内酯(GDL)为凝固剂,研制出牛奶豆腐.产品兼具牛奶和大豆的营养.以产品的感官为主要评定指标,确定了牛奶豆腐的最佳配方和工艺参数.     

丁位内酯系列的合成

丁位内酯系列的合成邝其汉，吴国湘，朱文渊，胡道华（广州市轻工研究所广州，５１００７５）本文叙述了用环戊酮和脂肪醛为起始原料，在碱性条件下进行缩合、脱水制得２－烯烃基环戊酮，随后在非钯催化剂存在下进行选择性加氢得２－烷基环戊酮，转化率和选择性平均都在９...     

2,2-二羟甲基丙酸合成新工艺研究

以甲醛、丙醛为原料,经羟醛缩合,产物不分离直接氧化制备得2 ,2 -二羟甲基丙酸。甲醛与丙醛的摩尔比为2 2∶1 ,在碳酸钾和三甲胺复合催化下,3 0～3 5℃下缩合反应2 4h;双氧水与丙醛的摩尔比为1 2∶1 ,在5 0℃开始滴加双氧水,滴加时间控制在2h以上,以5℃/0 5h的速度升温至90℃,在此反应温度下再氧化4h。产品收率(按丙醛计)达5 5 % ,熔点为1 80～1 84℃。     

牛奶豆腐研制

本文对牛奶豆腐的生产工艺进行了探讨,采用四因素三水平的正交实验确定了牛奶豆腐的最佳生产工艺条件。牛奶的添加量为１０％、葡萄糖－δ－酸内酯（ＧＤＬ）的用量为０．３０％、加热时间２０ｍｉｎ、加热温度８０℃。     

化学酶法合成D-泛解酸内酯的研究进展

泛酸俗称维生素B5,是辅酶A合成的前体,而D-泛解酸内酯是D-泛酸合成的前体.D-泛解酸内酯的化学合成是以甲醛和异丁醛为起始原料,经醛缩合、腈化及内酯化等反应生成DL-泛解酸内酯,再经选择性拆分得到D-泛解酸内酯.化学法与酶法相结合有助于高效、绿色地合成高光学纯度的D-泛解酸内酯.内酯水解酶催化混旋泛解酸内酯的选择性拆分已经成功地实现了工业生产.对羰基还原酶、醇脱氢酶和羟基腈裂合酶等在化学酶法合成D-泛解酸内酯中的最新进展进行了综述.     

δ-癸内酯的应用与合成研究进展

δ-癸内酯是一种动植物中的天然成分,广泛存在于椰子、覆盆子、奶酪、黄油、椰子和草莓等产品中。它是一种强烈而持久的奶油香味的特征成分,是制备奶油香精的重要原料。另外,它在食品中应用广泛,市场需求量大,已成为近年来国内外的研究热点。其制备方法可化学法和生物法两类,其中生物法制备的内酯类香料属于天然香料,深受消费者喜爱,同时也符合食品安全标准,具有更好的工业应用前景。本文主要介绍了δ-癸内酯在食品领域的应用,综述了近年来δ-癸内酯合成方法的相关进展,比较了化学和生物合成法在工业生产中存在的问题,旨在为δ-癸内酯在食品领域中的开发应用提供理论依据和参考。     

牛奶纤维氧化漂白工艺探讨与研究

介绍了牛奶纤维的氧化漂白工艺,研究了H2O2用量、工艺温度、硅酸钠用量对牛奶纤维白度的影响,根据检测结果获得最佳氧化漂白工艺。     

α—当归内酯的合成及在烟草香精中的应用

α-当归内酯是一种香味成分,它具有甜香、枫械香等多种香韵,在烟草香精中有广泛的用途。本文对α-当归内酯的合成方法进行了研究,提出了一条合理可行的的工艺路线;同时通过对α-当归内酯在烟用香精中的应用试验,证明了它是一种理想的烟草香味添加剂。     

二氢猕猴桃内酯的合成及作为卷烟香料的应用

经过三步反应即环化反应、Darzen反应和氧化反应,柠檬醛4转化成重要的挥发性香料组分二氢猕猴桃内酯1(9-氧杂-1,5,5-三甲基-双环[4,3,0]壬-6-烯-8-酮),总产率为33.5%。该合成方法的关键步骤是,β-环柠檬醛3与溴乙酸乙酯经过Darzen反应生成β-环高柠檬醛2。合成得到的二氢猕猴桃内酯1经mp、IR、MS、1HNMR和元素分析鉴定。结果表明,化合物1应用于烤烟型卷烟香料中具有增加卷烟香气,丰满卷烟香味和降低刺激的作用。      

Effect of antioxidant (alpha-tocopherol and ascorbic acid) fortification on light-induced flavor of milk

The effectiveness of added antioxidants against oxidation off-flavor development in light-exposed milk was evaluated using sensory and chemical analysis. Sensory testing for similarity showed no perceivable difference between control milk and milk with added (1) 0.05% alpha-tocopherol (TOC) and (2) 0.025% alpha-tocopherol and 0.025% ascorbic acid (TOC/ASC), but did demonstrate a perceivable difference when adding (3) 0.05% ascorbic acid (ASC) alone. Subsequently, sensory testing for difference showed a significant difference in oxidation off-flavor between light-exposed control milk and light-exposed milk with added TOC/ASC, whereas milk fortified with TOC was not different from control. Gas chromatography-olfactometry showed that more aroma-active flavor compounds were observed in light-exposed milk treated with TOC and TOC/ASC than light-exposed milk with no added antioxidants. The thiobarbituric acid reactive substances (TBARS) test verified chemically the extent of oxidation in control and antioxidant-treated milk samples. Milk that was exposed to light for 10 h showed a significantly higher TBARS value (0.92 +/- 0.09 mg/kg) than milk that was protected from light (0.59 +/- 0.184 mg/kg), or milk that was treated with TOC/ASC (0.26 +/- 0.092 mg/kg). Direct addition of low levels of antioxidants (TOC/ASC) to milk protected its flavor over 10 h of light exposed storage.     

Synthesis of 2-amino-6-(2-formyl-5-hydroxymethyl-1-pyrrolyl-)hexanoic acid

Summary The title compound has been synthesized by a novel route fromN -trifluoroacetyl lysine methyl ester and 2,9-dimethyldeca-2,8-diene-4,7-dione. Transformation of the pyrrole substituents and easy cleavage of protecting groups yields the compound in samples of high purity.

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Synthese der 2-Amino-6-(2-formyl-5-hydroxymethyl-l-pyrrolyl)-hexansäure

Zusammenfassung Die Titelverbindung wird auf einem neuen Weg ausN -Trifluoracetyllysinmethylester und 2,9-Dimethyldeca-2,8-dien-4,7-dion synthetisiert. Nach Umwandlung der Pyrrolsubstituenten und Abspaltung der Schutzgruppen unter milden Bedingungen erhält man die Titelverbindung in hoher Reinheit.

     

Short communication: Regulation of milk fat yield and fatty acid composition by insulin

Diet-induced milk fat depression in dairy cows has been known for many years and several theories have been proposed. One that continues to receive support is the glucogenic-insulin theory. Previous studies testing this theory using a hyperinsulinemic-euglycemic clamp have had variable results attributable to variability in the use of body fat reserves as a source of milk fatty acids. Our objective was to test the glucogenic-insulin theory using cows immediately postpartum, a period when the use of body fat for milk fat synthesis is greatest. During wk 2 postpartum, 5 cows were given a 2-d baseline period and then clamped for 4 d. Insulin was increased more than 2-fold during the clamp while the blood glucose concentration was maintained. Milk yield was not altered by administration of the clamp (38.7 vs. 39.0 ± 1.4 kg/d); however, the milk fat percentage and yield were reduced by 27% and plasma nonesterified fatty acids were reduced by 68%. Analysis of the milk fatty acid composition revealed that the decrease in milk fat yield during use of the clamp was almost exclusively due to reductions in preformed fatty acids; this is the exact opposite of what is observed with diet-induced milk fat depression. Therefore, our results do not support the glucogenic-insulin theory of diet-induced milk fat depression. The results further indicated that reductions in milk fat observed previously with hyperinsulinemic-euglycemic clamps or with glucose or propionate infusions were most likely consequences of the ability of insulin to inhibit lipolysis, thereby limiting the mammary availability of preformed fatty acids mobilized from body reserves.     

全同立构聚甲基丙烯酸接枝高分子纳米微球的合成

采用二步反应法,合成了立体等规性聚甲基丙烯酸大分子单体.用核磁共振表征了它的同规度和末端官能团(C=C)的含量.研究了分散共聚反应体系中大分子单体浓度对纳米微球直径和形态的影响.结果表明,在乙醇/水的混合溶液中使用合适的大分子单体浓度可得到直径单分散纳米微球,同时大分子单体浓度和相对分子质量将明显影响纳米微球的形成.     

Flavor and stability of pasteurized milk with elevated levels of conjugated linoleic acid and vaccenic acid

The objectives of this study were to determine if flavor differences between 2% fat pasteurized milks with and without naturally enhanced vaccenic acid (VA) and cis-9, trans-11 conjugated linoleic acids (CLA) levels could be detected over the commercial shelf life of the product and to determine if milk with elevated VA and cis-9, trans-11 CLA levels was more susceptible to development of light-induced oxidative flavor defects. Cows were fed a control diet or the same ration supplemented with 2% soybean oil and 1% fish oil (CLA diet). The milk, standardized to 2% fat, was pasteurized, homogenized, and stored in plastic containers at 4 degrees C. Oxidation was induced by exposing half of the containers to light. Testing was conducted at 1, 7, and 14 d postpasteurization. Average cis-9, trans-11 CLA content of the milks from the control and CLA diet groups was 0.52 and 4.74 g/100 g of fatty acids, respectively (8-fold increase). Average VA content of the milk from the control and CLA diet groups was 1.43 and 12.06 g/100 g of fatty acids, respectively (7.5-fold increase). Together, VA plus CLA represented almost 17% of the total milk fatty acids. There was no effect of light exposure on fatty acid composition initially or over the 14-d storage period. Although VA, cis-9, trans-11 CLA, and degree of unsaturation were significantly elevated in the milk from the CLA diet group, untrained panelists were unable to detect flavor differences initially or over time in 15 of 16 triangle test evaluations. Similarly, sensory results indicated no difference in susceptibility to the development of oxidized off-flavors between the milk from the control and CLA diet groups, even when oxidation was induced by light exposure.     

一种新的均三嗪类紫外线吸收剂ZLG-1的合成及表征

以三聚氯氰、间二甲苯为原料,经过Friedel-Craft反应,合成了2-氯-4,6-二（2＇,4＇二甲基苯基）-1,3,5-均三嗪（Ⅰ）,化合物Ⅰ在三氯化铝作用下再与间苯二酚反应,得到了2-（2’,4＇-二羟苯基）-4,6-二（2”,4”-二甲基苯基）-1,3,5-均三嗪（Ⅱ）．化合物Ⅱ在碱性条件下与环氧氯丙烷缩合并水解得到了该均三嗪类的紫外线吸收剂2-[2’-羟基-4’-（2＇＇＇,3＇＇＇）-二羟基丙烷氧基苯基]-4,6-二（2”,4”）-二甲基苯基-1,3,5-均三嗪（ZLG-1）,总收率为61．8％．讨论了反应温度、时间及反应物配比对各步反应收率的影响;并对化合物Ⅱ和ZLG-1的结构用IR、^1HNMR、MS进行了表征．由ZLG-1的UV光谱数据表明其紫外线吸收性能和三嗪-425相当．     

2-对甲氧基苯基-5-对硝基苯甲酰胺基-1,3,4-噻二唑合成与表征的研究

利用生物等排原理和亚结构连接法,对噻二唑的母体进行修饰,合成了新的化合物5-对甲氧基苯基-2-对硝基苯甲酰氨基-1,3,4-噻二唑。研究了温度对目标化合物合成得率的影响,并对其结构进行IR谱图分析。     

N-1,3,5-二氢二噻嗪基乙酸、2-（N-1,3,5-二氢二噻嗪基）丙酸和3-苯基-2-（N-1,3,5-二氢二噻嗪基）丙酸的合成及其香气特征

0℃下,在氨基酸的氢氧化钾溶液中,依次加入38%的甲醛、2mol/L的硫氢化钠溶液,充分搅拌反应,然后让其自然升至室温过夜,分别合成N-1,3,5-二氢二噻嗪基乙酸、2-（N-1,3,5-二氢二噻嗪基）丙酸和3-苯基-2-（N-1,3,5-二氢二噻嗪基）丙酸,收率分别为77.2%、73.7%和67.1%。这些化合物结构都通过IR、MS和1HNMR测试技术进行了表征,并对其进行了初步香味评价。结果表明,它们都具有硫磺样、热带水果样香味特征,阈值为18.5～30.7mg·kg-1。