牡蛎糖原的研究(II)——牡蛎糖原的分子结构

本文应用酶法研究了牡蛎糖原的精细分子结构。结果显示牡蛎糖原的分子结构参数-平均链长,外链和内链平均长分别为13、9和3;用异淀粉酶和普鲁兰酶对牡蛎糖原的β-极限糊精进行顺序脱支,结果表明牡蛎糖原的A,B链比值为0.88:1.0,分支化度为1.88。     

香料烟中游离氨基酸含量随施肥量的变化

对依兹密尔香料烟3个部位烟叶中的游离氨基酸含量随施肥量的变化进行了研究,结果表明:(1)在同等施肥量条件下,成熟鲜烟叶中总游离氨基酸的含量随烟叶着生部位的升高而增加,但每一种氨基酸的表现又有所不同;(2)不同部位烟叶总游离氨基酸的含量与施肥量的关系规律表现不明显;(3)在施肥量较低(纯氮30～37.5kg/hm2)时各部位烟叶中苯丙氨酸、脯氨酸、天门冬氨酸和谷氨酸的含量总体表现较高,这有利于提高烟株的抗病性和烟叶质量。     

太平洋牡蛎,僧帽牡蛎和近江牡蛎中游离氨基酸和牛磺酸的分析

本文通过对牡蛎软件中牛磺酸含量，必需氨基酸的配比等方面的探讨，分析了牡蛎所具有的营养价值和开发利用前景。     

制丝过程中烤烟内游离氨基酸含量的变化

为了解烟草中游离氨基酸在制丝过程中的变化,对不同工序进行在线取样,采用柱前衍生反相高效液相色谱法对烟草中的游离氨基酸进行了分析,并进行了对比评吸。结果表明,烟草中游离氨基酸的含量在加料后稍微增大;在贮片过程中明显降低;烘丝后部分增加、部分降低;贮片过程中游离氨基酸含量的降低对提高卷烟的感官质量作用明显。     

卤猪肉加工过程中游离脂肪酸、游离氨基酸及核苷酸变化分析

利用气相色谱质谱联用和高效液相色谱法检测分析了卤猪肉加工过程中游离脂肪酸、游离氨基酸及核苷酸的变化。结果表明,在加工过程中,总游离脂肪酸有效峰面积呈下降趋势,饱和脂肪酸也呈现下降的变化趋势,不饱和脂肪酸含量先增加后减少,在高温煮制1 h时达到最大值。总游离氨基酸的含量在卤猪肉加工过程中变化明显,在原料肉中总游离氨基酸含量为244.39 mg/100 g,其它样品中含量都显著(p0.05)高于原料肉,在二次煮制完成后达到最大值,为349.32 mg/100 g。谷氨酸在成品中的含量达到119.02mg/100 g,占总游离氨基酸的34.12%。呈味核苷酸检测结果显示,在加工过程中5'-IMP和5'-GMP的含量呈现下降趋势。由于加热导致核苷酸热降解,其降解产物肌苷的含量呈现上升趋势,在成品中检测到其含量显著(p0.05)高于原料肉中的含量。本研究结果为改进卤猪肉的生产工艺、提高产品品质提供了理论参考。     

烟草旺长期叶片游离氨基酸的含量

烟叶中含１６种以上游离氨基酸，但叶脉中缺乏组氨酸。在叶片中，随首叶位层次的提高，总游离氨基酸含量逐渐提高；在叶脉中，顶叶总游离氨基酸含量最高，脚叶次之，腰叶最低，不管是叶片还是叶脉，从氨酸居其他各种氨基酸含量之首。     

高压处理的绵羊肌肉中游离氨基酸含量变化研究

本文研究了绵羊肌肉样品经高压和不同的施压温度和施压时间处理,在-80℃条件下冻藏115天,经解冻后测得的样品中各游离氨基酸含量表明,随着压力由100MPa提高到700MPa处理组中的游离氨基酸--苏氨酸、丙氨酸、蛋氨酸、异亮氨酸、亮氨酸、脯氨酸的含量均比对照组高,并且随着施压时间由5min提高到20min苏氨酸、丙氨酸、异亮氨酸、苯丙氨酸含量比对照组均有提高.研究结果说明高压处理对肌肉中有利于增强风味的游离氨基酸的形成具有明显促进作用.     

牡蛎糖原的研究(I)——牡蛎糖原的分离提取和化学组成

用热碱法提取牡蛎中的糖原,经纯化后得到几乎不含有蛋白质的糖原样品。凝胶过滤色谱结果表明,牡蛎糖原相对分子质量在数百万至数千万之间。气相色谱测定结果表明,牡蛎糖原只含有葡萄糖残基,是一种均一多糖。     

弥渡卷蹄腌制前后游离氨基酸的变化

测定采用传统工艺配方和改进工艺配方加工的弥渡卷蹄在腌制前后游离氨基酸的变化,结果表明:无论采用那种工艺配方加工,弥渡卷蹄在腌制后大多游离氨基酸的含量和游离氨基酸的总量均明显增多,采用改进工艺和配方加工的弥渡卷蹄在腌制前后游离氨基酸总量高于采用传统工艺和配方加工的弥渡卷蹄。     

烟草旺长期叶片游离氨基酸的含量

烟叶中含１６种以上游离氨基酸，但叶脉中缺乏组氨酸。在叶片中，随着叶位层次的提高，总游离氨基酸含量逐渐提高；在叶脉中，顶叶总游离氨基酸含量最高，脚叶次之，腰叶最低。不管是叶片还是叶脉，谷氨酸居其他各种氨基酸含量之首。主题词     

酱油渣蛋白质的分离、鉴定和氨基酸组成特征研究

本文以酱油上清液为对照,以过滤-冷冻真空干燥法制备了酱油渣。首先,对比研究了酱油渣的常规理化指标。其次,以SDS-PAGE、MALDI-TOF/TOF MS和HPLC法对酱油渣和酱油上清中蛋白质分子量分布、来源与种类及氨基酸组成特征进行了研究。结果显示酱油渣（湿渣）主要由15.98%的碳水化合物、10.19%的蛋白质、10.10%的食盐和59.50%的水分组成。SDS-PAGE和MALDI-TOF/TOF MS分析结果显示酱油渣蛋白质主要由分子量约为19.3 kDa（a, 59.40%）、31.8 kDa（b, 12.91%）和12.3 kDa（c, 27.69%）的蛋白质亚基组成,经质谱鉴定分子量为19.3 kDa的多肽（a）为Glycinin G4亚基碱性端B3。酱油渣蛋白质氨基酸组成分析表明,与酱油上清中蛋白质相比,酱油渣蛋白质中疏水性氨基酸含量和平均疏水值明显高于酱油上清中蛋白质。上述差异是酱油渣蛋白质氨基酸组成的主要特征,也是酱油渣蛋白质水溶性差和形成的主要原因。     

九龙牦牛奶渣氨基酸含量和蛋白质组成分析

本研究的目的是分析家庭自制的九龙牦牛奶渣中氨基酸含量和蛋白组成特点。结果显示,九龙牦牛奶渣中总氨基酸含量约为36.5%,含量高的氨基酸主要包括谷氨酸、脯氨酸、亮氨酸、天冬氨酸、赖氨酸。必需氨基酸占总氨基酸的比例约为36%。电泳分析显示,牦牛奶渣蛋白质组分以酪蛋白为主,其比例约为82%。实验观察到牦牛酪蛋白的初步降解。研究结果表明,九龙牦牛奶渣的生化组成与普通牦牛奶渣接近。     

酵母抽提物中游离氨基酸的测定与分析

本文首先摸索了游离氨基酸的HPLC法测定条件,建立了同时测定16种游离氨基酸的方法,然后对酵母抽提物中的游离氨基酸进行了分析研究。通过高效液相色谱法测定了热反应前后酵母抽提物、HVP粉、猪肉酶解物中的游离酸,得出结论：酵母抽提物中游离氨基酸的种类和含量最多;热反应后的酵母抽提物中氨基酸含量减少,且随着加入还原糖（木糖）含量的增多,游离氨基酸含量也随着减少。因此,酵母抽提物可作为Maillard反应制备肉味香精的良好氨基酸原料。     

Properties of Free Radicals in Protein and Amino Acid Pyrolysates

The ESR intensities (g=2.0042 ～ 2.0053) of free radicals in L-lysine and casein pyrolysates increased with increase of the heating time. In L-lysine pyrolysate (200°C, 20 min), the fraction insoluble in organic solvents and water accounted for 48.1% of the ESR intensity of the whole pyrolysate; the component responsible appeared to be a product of condensation polymerization, but the elemental analysis data indicated a smaller value for nitrogen than that expected for polylysine. The pyrolysis of casein brought about denatured products insoluble in water. The free radicals formed were stable for a week in distilled water and were unaffected by digestion with pepsin or pancreatin (37°C for 3 hr).     

利用米渣蛋白制备氨基酸饮料

以味精厂下脚料米渣为原料，利用木瓜蛋白酶对米渣水解。通过正交试验和验证试验确定酶解米渣蛋白的最适条件，利用其酶解液可配制成氨基酸蛋白饮料。氨基酸蛋白饮料中含蛋白质182．35mg／dL，8种必需氨基酸占总蛋白质的质量分数为39％。     

Flavor and Free Amino Acid Composition of Lavender and Eucalyptus Honeys

Unifloral honeys have highly characteristic flavors due to various volatiles probably derived from the original plant sources. The volatile compounds of honeys from two unifloral sources, lavender and eucalyptus, were investigated. Volatile compounds were extracted with dichloromethane, followed by Likens-Nickerson's simultaneous steam distillation/solvent extraction. The extracts had an intense honey aroma that varied with the type of honey. Compounds (400) were separated by gas chromatography and detected by mass spectrometry. Major flavor compounds were very characteristic of each floral source (linear aldehydes, n-hexanol, coumarin, and phenylacetaldehyde in lavender honeys; di-ketones, hydroxyketones, 3-hexanol, sulfur compounds, and alkanes in eucalyptus samples).     

羊毛氨基酸残基模拟化合物与DCCA反应情况初探

在实验的基础上确立以佛尔哈佛法为基础的沉淀滴定法,并用以分析DCCA与酪氨酸残基--苯酚的反应情况。实验结果表明,温度及pH影响参加氯化及氧化反应的有效氯的比例,可见优化工艺有助于控制羊毛防缩处理过程中AOX的生成。     

Effect of Environmental Salinity on the Free Amino Acid Composition and Concentration in Penaeid Shrimp

White shrimp, Penaeus vannamei, kept in laboratory aquaria at a salinity of 35 parts per thousand (ppt) were subjected to increased and decreased salinity changes by either 5, 15 or 25 ppt. Shrimp were periodically removed from the aquaria and analyzed for total free amino acid nitrogen and also specific free amino acid composition. Decreasing salinities resulted in corresponding decreases in free amino acid concentration; minimum values were reached after 24 - 48 hr. Increasing salinities were likewise shown to result in corresponding increases in the tissue free amino acid concentration with maximum values being reachedin 24 hr. Glycine, proline, arginine, serine/threonine, and alanine were the most significant contributors, comprising from 93 - 96% of the total free amino acid pool.     

Protein and Amino Acid Solubilization using Bacillus cereus, Bacillus velesensis, and Chryseobacterium sp. from Chemical Extraction Protein Residue

The exploitation of natural resources and increased environmental pollution have stressed the need for more valued use of residues generated by the fish processing plants, and species with low commercial value. Protein hydrolysis processes—whether chemical or enzymatic—generate insoluble proteins from bones, scales, and skin, which are not recovered and are often used as animal feed or disposed off into the environment. As an alternative, insoluble proteins could be converted in useful biomass protein concentrates or amino acids, by using microbial proteases. This work examines the solubilization of insoluble proteins discarded in the process of pH change in fish residues from Whitemouth croaker (Micropogonias furnieri), through the use of bacterial proteases. Temperature and pH conditions in the fermentations were adjusted for each microorganism and time was set at 96 h. Two substrates (acid and alkaline), three microorganism strains, and the substrate concentration used were examined. Among the three strains, Bacillus velesensis reached the higher proteolytic activity (47.56 U mL⁻¹), followed by Chryseobacterium sp. with 23.46 U mL⁻¹. Bacillus cereus (3.13 U mL⁻¹) showed low proteolytic activity. B. velesensis was the bacterium that presented better results with the analyzed substrates, achieving larger amount of soluble protein and free amino acids. The findings showed that these bacteria could be used to solubilize proteins from fish byproducts, which may be particularly useful to increase the yield of hydrolysis process or food formulations.