SDS-PAGE方法测定宠物食品蛋白热变性程度

将干性宠物食品样品先用双蒸水处理,然后对加热处理和未加热处理的相同样品,采用SDS-PAGE(十二烷基硫酸钠-聚丙烯酰胺凝胶电泳)方法测定宠物干性食品蛋白热变性程度,以确保加工出厂的宠物干性食品中心温度达到规定的加热温度及加热时间.     

SDS—PAGE宠物食品蛋白方法测定热变性程度

将干性宠物食品样品先用双蒸水处理，然后对加热处理和未加热处理的相同样品，采用SDS—PAGE（十二烷基硫酸钠-聚丙烯酰胺凝胶电泳）方法测定宠物干性食品蛋白热变性程度，以确保加工出厂的宠物干性食品中心温度达到规定的加热温度及加热时间。     

虾头自溶脱蛋白法制备壳聚糖的新工艺

为探索以虾头制备壳聚糖的新工艺,采用紫外照射激活虾头内自溶酶,水解脱除蛋白质替代传统的碱加热处理法,对工艺条件进行了优化,确定了紫外照射15 min、自溶3h脱蛋白,8%HCl室温处理3h脱钙,50%NaOH,130℃加热2h脱乙酰,制备的壳聚糖符合质量标准.与传统法和加酶水解法相比较,自溶法生产成本降低,操作简单,对环境污染减少,极具应用前景.     

婴幼儿配方乳粉中乳清蛋白检测及蛋白热变性的研究进展

介绍了乳清蛋白中蛋白的生理功能和蛋白热变性的结构变化,讨论了各检测方法的优缺点并对其方法的优化改善研究归纳总结,对乳清蛋白检测的研究提出建议,以期为开发新的检测方法提供思路。     

蛋白溶解性分析法研究大米焙炒过程中蛋白质热变性行为

考察了焙炒过程中大米蛋白质的热变性行为,通过大米蛋白在不同功能溶剂中的溶解度变化了解大米蛋白质在焙炒过程中次级结构的变化及热变性信息。发现热变性主要发生在焙炒的前期,热变性包括蛋白质次级结构的变化和更高能级的化学变化。与传统蒸煮方法相比,焙炒大米的蛋白质热变性程度较低。粳米和糯米中的蛋白质热变性行为基本相似,选用不同的加热介质对大米蛋白的热变性没有影响。     

蛋白溶解性分析法研究大米焙炒过程中蛋白质热变性行为

考察了焙炒过程中大米蛋白质的热变性行为,通过大米蛋白在不同功能溶剂中的溶解度变化了解大米蛋白质在焙炒过程中次级结构的变化及热变性信息。发现热变性主要发生在焙炒的前期,热变性包括蛋白质次级结构的变化和更高能级的化学变化。与传统蒸煮方法相比,焙炒大米的蛋白质热变性程度较低。粳米和糯米中的蛋白质热变性行为基本相似,选用不同的加热介质对大米蛋白的热变性没有影响。      

虾头水解蛋白脱苦脱腥方法的研究

为去除虾头水解蛋白溶液的苦腥味,比较了粉末活性炭吸附法、酵母发酵法和环状糊精包埋法的脱苦脱腥效果。结果表明,酵母发酵与β-环糊精包埋联合去除苦腥味的效果最佳。通过添加1.5%的β-环糊精,60℃包埋60min,然后添加1%的酵母,在40℃下恒温发酵60min,离心分离后沸水浴5min。处理后的虾头水解蛋白液无苦腥味,且具有浓郁的鲜虾风味。     

虾头的综合加工技术

<正> 对虾是我国出口创汇的重要水产品之一,在国际市场上享有盛誉。虾头是对虾加工的副产品,约占整个虾重的三分之一,我国仅北方每年加工对虾产生的虾头就有4万吨左右。目前,这些虾头没有得到充分地利用,造成的浪费较大。 虾头含丰富的营养物质,可食部分占相当的比重,虾头的粗蛋白约13％,粗脂肪9％。虾体60％以上的自溶酶存在于虾头内。另外还含有风味独特的     

虾头酱的研制

以斑节对虾的虾头和虾壳为原料 ,经油炸、配料、粉碎、磨浆、罐装、包装等工序得到虾头酱。结果表明 ,产品含 18种氨基酸 ,其中 8种必需氨基酸占总氨基酸的 3 3 1% ,蛋白质的氨基酸分为 88;矿物质Ca、Fe含量丰富 ,产品自身具有较强的防腐抑菌能力 ,常温贮藏 12个月后其细菌总数为 2 480 0个 /g ,低于同类虾酱产品的国家标准。是一种营养丰富且不含防腐剂的新型的天然海鲜调味品。     

乳清蛋白的热变性及其在酸乳生产中的应用

介绍了乳清蛋白与酪蛋白热缔合过程的模型，乳清蛋白热变性的动力学以及热变性作用对酸奶质构的影响，乳清蛋白的变性度与酸奶最终质量存在密度的关系。应用β－乳球蛋白的等变性度曲线可以选择酸奶生产中的最适热处理条件。     

Determination of Whey Protein Denaturation in Heat-Processed Milks: Comparison of Three Methods

Fast protein liquid chromatography was used to determine the extent of whey protein denaturation in various heat-treated milk samples: Sordi-indirect UHT (145°C/3 s), Dasi-direct UHT (142°C/3 s), HTST (80°C/30 s), and batch (63°C/30 min). Results were compared with other published methods (differential scanning calorimetry, whey protein nitrogen index, and Kjeldahl nitrogen on salt fractions). Results of the differential scanning calorimetry method were too erratic to be used to quantify whey protein denaturation. The remaining methods (fast protein liquid chromatography, Kjeldahl nitrogen, and whey protein nitrogen index) gave reproducible results and the extent of denaturation (highest to lowest) was consistently predicted as Sordi > Dasi > HTST > batch. There was no difference between fast protein liquid chromatography and Kjeldahl nitrogen, but there was a significant difference between fast protein liquid chromatography and whey protein nitrogen index and between Kjeldahl nitrogen and whey protein nitrogen index. Fast protein liquid chromatography appears to be an effective method to determine whey protein denaturation in heat-treated milks.     

油菜蜂花粉蛋白水解度测定方法比较

采用Alcalase 2.4L FG 水解油菜蜂花粉蛋白,比较pH stat 法、OPA 法和TNBS 法测定蜂花粉蛋白水解度的差异。水解118min 后,pH stat 法、OPA 法和TNBS 法测得的水解度分别为24.7% ﹑ 13.4% ﹑ 6.6%。由于OPA试剂和甘氨酸﹑半胱氨酸﹑赖氨酸反应生成的化合物在340nm 波长处的吸光度较低,致使OPA 法测得的水解度低。TNBS 试剂和ε-NH2 的作用不稳定,也可能是由于TNBS 试剂产生的发光物使测定结果降低。在水解度较低的情况下,α-NH2 平均解离度的变化可以忽略,pH stat 法测得的水解度比较准确。     

虾壳蛋白质营养价值的评价

采用盐酸处理虾头、壳获得蛋白质含量为７６．５５％、钙１５．２％、磷５．２８％的虾头、壳蛋白质。必需氨基酸指数为８８．１３％。化学分为０．９０１３。大鼠实验结果表明，虾头、壳蛋白的蛋白质功效比值、生物价和蛋白质净利用率依次为２．７９２、３．４７７、８０．７９８％和７８．１５３％。各项指标均与牛奶粉蛋白质无显著性差异（ρ〉０．０５）。表明虾头、壳蛋白具有优良的营养价值。     

蛋白溶出与变性结合消减虾仁致敏性

以南美白对虾虾仁为原料,采用高压下蛋白溶出与变性相结合的方法消减虾仁致敏性。在室温下采用不 同压力（0.1～900.0 MPa）处理虾仁,确定适合虾仁蛋白溶出和变性的压力条件,并以虾仁蛋白致敏性的消减效果 为指标确定虾仁的处理条件。结果显示,在200.0 MPa下保压处理30 min,有利于虾仁蛋白的溶出;当压力大于等 于500.0 MPa时,可引起虾仁蛋白的变性;当压力在600.0 MPa时,虾仁蛋白的致敏性最小。将虾仁在200.0 MPa下 处理30 min后,再用600.0 MPa处理30 min,虾仁的致敏性消减率大于80%。因此,高压处理可消减虾仁的致敏性, 采用适合蛋白溶出与变性相结合的压力处理,能够提高虾仁致敏性消减效果。     

虾头自溶产物苦味与蛋白平均疏水度联系及脱苦

为了探明虾头自溶产物中苦味肽的分布以及蛋白疏水性与苦味的联系,采用超滤将虾头自溶产物分成不同组分,分别检测其苦味与平均疏水度,并研究自溶过程中添加复合风味蛋白酶协同水解虾头对苦味的改善作用。结果表明：虾头自溶产物的苦味主要来自分子质量为3～5kD 的肽;不同分子质量大小的自溶产物,平均疏水度越小苦味越大;添加复合风味蛋白酶协同水解虾头,与自溶比较,其蛋白回收率提高了3.5%,苦味降低了50%。     

蛋白质组分分析方法比较研究

采用蛋白质连续累进提取法与组分快速提取法测定了21个小麦面粉样品的蛋白质组分，以比较两种蛋白质组分分析方法的特点。连续累进提取法将小麦蛋白质分离成清蛋白、球蛋白、醇溶蛋白和谷蛋白；快速提取法将小麦蛋白质分离成单体蛋白、可溶性谷蛋白和不溶性谷蛋白。结果表明：单体蛋白与清蛋白、球蛋白、醇溶蛋白含量及清蛋白、球蛋白、谷蛋白之和均无关系；可溶性谷蛋白含量与清蛋白、弱化度呈负相关，与醇溶蛋白、谷蛋白、沉淀值呈极显著或显著正相关；不溶性谷蛋白与醇溶蛋白、谷蛋白、沉淀值、稳定时间、评价值、弱化度呈极显著或显著相关。连续累进提取法适合于小麦品质常规检测，快速提取法适用于小麦早代材料品质检测。两种方法对于预测小麦的加工品质有着相同的重要作用，应根据样品量及检测精度进行选择。     

超声辅助酶法水解虾头蛋白工艺优化

为提取虾头蛋白制备虾味调味品,提高虾头副产物的附加值,优化虾头酶解工艺。并探讨虾头酶解液在模拟鱼翅加工中的利用。通过超声波辅助木瓜蛋白酶法提取虾头蛋白,探讨超声功率、超声时间、粒径、酶解温度、pH值、料液比、酶添加量、酶解时间对虾头蛋白水解度的影响,通过响应面试验法优化提取工艺。通过向模拟鱼翅胶液中添加不同含量虾头酶解液的水溶液,探讨酶解液含量对模拟鱼翅感官的影响。超声波辅助酶法提取虾头蛋白的最佳提取条件为:按料液比1∶10(g/mL),酶添加量8 000 U/g,粒径0.2 mm~0.3 mm的虾头中添加木瓜蛋白酶,调节pH值至7.5,在超声功率120 W条件下处理20 min后,60℃下酶解时间3 h,此条件下虾头蛋白的水解率可达65.25%(以虾头蛋白质量计)。添加80%虾头酶解液制备的模拟鱼翅已具备较优的感官特性。     

Distribution of Proteolytic Activity in the Different Protein Fractions of Tropical Shrimp Head Waste

Ammonium sulfate fractionated protein fractions at levels of 25%, 30%, 35%, 40%, 42.5% and 45% ammonium sulfate were recovered from the head waste of tropical marine tiger (MTS), culture tiger (CTS), white (WS) and brown shrimp (BS) and then characterized for protease activity. Distribution of buffer (pH 7.1) extracted protein among ammonium sulfate fractions showed that total protein in 25% fraction of MTS, CTS, WS and BS was 48, 54, 34 and 24 times more than that in the respective 42.5% fraction of the head waste of these shrimps. The highest proteolytic activity was observed in 42.5% (NH₄)₂SO₄ protein fraction of the head waste of MTS, CTS, WS and BS, the values were 19, 1.7, 11.6 and 2 times, respectively, more than that of the corresponding 25% (NH₄)₂SO₄ protein fractions. Highest caseinolytic activity (pH 8.5) and gelatinolytic activity (pH 7.1) was observed in the 42.5% fraction of the head waste of CTS and WS, respectively; but the highest albuminolytic activity (pH 8) was observed in the same fraction of the head waste of both MTS and BS. The optimum pH for highest gelatinolytic and albuminolytic activity of the 42.5% (NH₄)₂SO₄ protein fraction of the head waste of MTS and BS was 4; the same for highest gelatinolytic activity of the same protein fraction of the head waste of WS, and these fractions included acid proteases such as pepsin, the optimum pH for the above activity of the same fraction of CTS was 6-8.5, and the fraction was an alkaline protease such as chymotrypsin. The SDS-PAGE pattern of 42.5% (NH₄)₂SO₄ protein fraction of the head waste of BS, CTS, WS and MTS was almost similar with a dark band close to the marker band 20kDa. Proteases make up to 48% of industrial enzymes and are mostly used in detergents, leather production and food industry.     

Distribution of Proteolytic Activity in the Different Protein Fractions of Tropical Shrimp Head Waste

Ammonium sulfate fractionated protein fractions at levels of 25%, 30%, 35%, 40%, 42.5% and 45% ammonium sulfate were recovered from the head waste of tropical marine tiger (MTS), culture tiger (CTS), white (WS) and brown shrimp (BS) and then characterized for protease activity. Distribution of buffer (pH 7.1) extracted protein among ammonium sulfate fractions showed that total protein in 25% fraction of MTS, CTS, WS and BS was 48, 54, 34 and 24 times more than that in the respective 42.5% fraction of the head waste of these shrimps. The highest proteolytic activity was observed in 42.5% (NH₄)₂SO₄ protein fraction of the head waste of MTS, CTS, WS and BS, the values were 19, 1.7, 11.6 and 2 times, respectively, more than that of the corresponding 25% (NH₄)₂SO₄ protein fractions. Highest caseinolytic activity (pH 8.5) and gelatinolytic activity (pH 7.1) was observed in the 42.5% fraction of the head waste of CTS and WS, respectively; but the highest albuminolytic activity (pH 8) was observed in the same fraction of the head waste of both MTS and BS. The optimum pH for highest gelatinolytic and albuminolytic activity of the 42.5% (NH₄)₂SO₄ protein fraction of the head waste of MTS and BS was 4; the same for highest gelatinolytic activity of the same protein fraction of the head waste of WS, and these fractions included acid proteases such as pepsin, the optimum pH for the above activity of the same fraction of CTS was 6–8.5, and the fraction was an alkaline protease such as chymotrypsin. The SDS-PAGE pattern of 42.5% (NH₄)₂SO₄ protein fraction of the head waste of BS, CTS, WS and MTS was almost similar with a dark band close to the marker band 20kDa. Proteases make up to 48% of industrial enzymes and are mostly used in detergents, leather production and food industry.