不同亲水胶体对带鱼鱼糜凝胶品质的影响

为确定合适的亲水胶体种类及其添加量,以带鱼鱼糜为原料,通过测定凝胶强度、质构(硬度、粘聚性、弹性和咀嚼性)、白度、持水性和凝胶溶解度等指标,分析瓜尔胶、魔芋胶和沙蒿胶3种亲水胶体对带鱼鱼糜凝胶品质的影响。结果表明,瓜尔胶、魔芋胶和沙蒿胶均能提高带鱼鱼糜凝胶强度,但相同添加量下魔芋胶的改善效果最好,而瓜尔胶对鱼糜凝胶强度的影响不显著。魔芋胶能显著改进带鱼鱼糜凝胶的质构特性;瓜尔胶添加量为2.0%时鱼糜凝胶硬度、弹性、咀嚼性、粘聚性比对照组低;沙蒿胶对鱼糜凝胶的粘聚性影响显著,当添加量为1.5%或2.0%时,带鱼鱼糜凝胶的咀嚼性、硬度增加,弹性下降。瓜尔胶、魔芋胶和沙蒿胶均能提高带鱼鱼糜持水性,降低鱼糜凝胶白度和溶解度,但对鱼糜凝胶色泽的影响不显著。扫描电镜结果显示,1.5%魔芋胶处理组形成的鱼糜凝胶表面规则有序、网络结构致密均一。综合比较,添加1.5%魔芋胶能有效改善带鱼鱼糜的凝胶品质。本研究结果为提高带鱼鱼糜制品品质及生产研发提供了一定的理论依据。     

猪皮明胶提取过程中的超高压预处理工艺优化

传统的酸碱法预处理明胶的生产工艺中存在生产周期长、酸碱产生的污染严重等问题,探索用超高压预处理的新工艺,以期改进明胶传统生产工艺,建立清洁高效的方法。以新鲜猪皮为原料,以提取率和凝胶强度为评价指标,以不进行预处理、传统酸处理为对照,研究比较了添加不同传压介质的超高压预处理对猪皮提胶效果的影响,从而选出效果较优的超高压预处理方法,进一步对超高压压力、超高压时间、酸质量分数等因素进行优化研究。结果显示,超高压有助于提高明胶提取率和凝胶强度,在超高压处理组中以酸/超高压组的提胶效果最优,较优的提胶工艺条件为超高压压力250MPa、超高压时间10min、HCl质量分数0.75%。在此条件下,猪皮明胶提取率可达88.62%,凝胶强度可达384.43g。SDS-PAGE电泳分析结果表明酸/超高压组明胶的α、β、γ等亚基组分含量较高,这可能是其高凝胶强度的原因所在。研究结果可为超高压技术在明胶制备中的应用乃至明胶清洁生产工艺的建立提供技术参考。     

高压预处理对猪肉匀浆物凝胶质构特性的影响

采用均匀试验设计,研究不同压力和保压时间预处理对猪肉匀浆物凝胶质构特性的影响。结果表明,质构特性参数与压力和保压时间之间呈非线性关系,除凝胶弹性外,压力和保压时间对其他指标的影响均存在一定程度的互作。凝胶强度和咀嚼性在压力较低时随着保压时间的延长而下降,而压力较高时则相反;在保压时间较短时随着压力的增大而降低,保压时间较长时则相反。凝胶硬度在一定压力条件下随着保压时间的延长呈先升后降的趋势;在保压时间较长时随着压力的增大而增大,当保压时间较短时则相反。凝胶的弹性在一定压力条件下随着保压时间的延长呈先降后升的趋势;在保压时间不变时随着压力的增大而减小。凝胶的胶粘性在一定压力条件下随着保压时间的延长而增大,在保压时间不变时随着压力的增大而增大。     

淀粉对竹荚鱼鱼糜流变性质和凝胶特性的影响

为探讨改善竹荚鱼鱼糜凝胶品质的最佳淀粉种类和添加量,利用流变仪、质构仪、扫描电镜等方法研究了不同来源的原淀粉及其添加量对竹荚鱼鱼糜流变性质和凝胶特性的影响。动态流变性质的结果表明,在加热过程中,竹荚鱼鱼糜的弹性模量G' 经历了2个阶段的变化,首先在20～57℃时G' 逐渐降低;然后在57～80℃由于凝胶网络的形成,使G' 增加。添加淀粉显著影响竹荚鱼鱼糜的G'。添加淀粉能够提高竹荚鱼鱼糜的凝胶强度。添加木薯淀粉、小麦淀粉对改善竹荚鱼鱼糜凝胶品质的效果最好,其添加量为4%,竹荚鱼鱼糜凝胶的凝胶强度分别提高了158%和155%。添加淀粉能提高竹荚鱼鱼糜凝胶的持水性。在相同的添加量时,木薯淀粉和小麦淀粉对提高竹荚鱼鱼糜凝胶的持水性的效果最好。添加淀粉能显著提高竹荚鱼鱼糜凝胶的白度,但淀粉的种类和添加量对鱼糜凝胶色泽的影响不显著。     

乙酰化二淀粉磷酸酯对再加热鱼糜凝胶冻藏特性的影响

为探究乙酰化二淀粉磷酸酯（ADSP）添加量对再加热鱼糜凝胶冻藏品质的影响,本研究以冷冻阿拉斯加狭鳕鱼糜为原料,改变二段加热的凝胶化过程,对鱼糜进行低温预凝胶-冷冻贮藏-高温再加热处理,分析冻藏期间鱼糜凝胶的微观结构、失水率、水分分布状态、质构特性和动态粘弹性。结果表明,随着冻藏时间的延长,鱼糜凝胶的孔隙变大,失水率增加,不易流动水减少,自由水增加,硬度和胶粘性先下降后上升,粘附性增大,内聚性无变化,动态粘弹性下降。在同一冻藏周期下,随着ADSP添加量的增加,鱼糜凝胶的孔隙变小,失水率降低,水分分布状态较稳定,其中5%和7%添加量的效果较好;质构特性结果显示,ADSP添加量的增加有利于提高再加热鱼糜凝胶品质,虽然添加量为5%和7%的鱼糜凝胶硬度、内聚性和胶粘性基本一致,但5%添加量的鱼糜凝胶的粘附性在冻藏期间开始增加的时间较晚且变化幅度较小;动态粘弹性结果显示,高温加热后期5%添加量的鱼糜凝胶的储能模量最高,其次是7%添加量;在损耗模量中,7%添加量的鱼糜凝胶粘性最高,其次是5%添加量。综合分析认为,添加5%ADSP能有效降低再加热鱼糜凝胶在冻藏期间的品质变化。本研究结果为冷冻鱼糜制品的...     

鱿鱼与白鲢鱼混合比例对鱼糜制品凝胶特性的影响研究

为了改善鱿鱼与白鲢鱼混合鱼糜制品的凝胶特性,本研究通过鱼糜制品的感官评价、凝胶强度、持水性、白度、水分分布、肌原纤维蛋白凝胶电泳和光学显微镜观察等指标,分析鱿鱼与白鲢鱼混合比例对鱼糜制品凝胶特性的影响。结果表明,当鱿鱼与白鲢鱼混合比例为3∶4时,凝胶特性最好,其中鱼糜凝胶的凝胶强度及持水性较混合比例为5∶2时分别提高了42.74%和2.93个百分点;感官评价总分、白度值显著高于其他混合比例（P<0.05）,分别为76.3和72.3,不易流动水相对含量显著高于其他混合比例（P<0.05）,且该比例下鱼糜凝胶网络结构致密均一,对水分的束缚能力强。肌原纤维蛋白电泳结果显示,混合比例为3∶4时,肌球蛋白重链交联程度高,形成了大分子聚集体。综上,当鱿鱼与白鲢鱼混合比例为3∶4时,可明显改善混合鱼糜制品的凝胶品质。本研究结果为提高鱿鱼鱼糜制品的凝胶品质及生产研发提供了一定的理论依据。     

超高压和瓜尔胶对鸡肉盐溶蛋白凝胶的影响

本文以鸡胸肉为原料,提取盐溶蛋白并进行超高压处理,SDS-PAGE法测定超高压处理的盐溶蛋白,研究了超高压和瓜尔胶对鸡胸肉盐溶蛋白及凝胶性质的影响。结果显示:随处理压力的增大,盐溶蛋白浓度显著降低,蛋白溶液的pH值逐渐升高,凝胶强度、胶黏度等显著提高,凝胶弹性变化趋势则是先增后减;超高压使大分子量的蛋白变性程度明显,中小分子量的蛋白电泳条带变化较复杂。试验证明:超高压能够改变大分子蛋白的结构,使其断开为中小分子,利于被机体吸收利用;瓜尔胶的添加有助于凝胶特性的增强,对于食品中凝胶的利用有较大的意义。     

不同淀粉对带鱼鱼糜凝胶品质的影响

为确定改善带鱼鱼糜凝胶品质的最佳淀粉种类及其添加量,以凝胶强度、质构分析(TPA)值、白度、持水性和凝胶溶解度为指标,探究5种淀粉(小麦淀粉、马铃薯淀粉、木薯淀粉、交联淀粉和羟丙基淀粉)在不同添加量(0、5%、10%、15%和20%)下对带鱼鱼糜凝胶品质的影响。结果表明,不同种类淀粉以及添加量均对带鱼鱼糜凝胶品质有显著影响。当添加量超过15%后,淀粉的添加对带鱼鱼糜凝胶弹性和持水性影响不显著。5种淀粉中,木薯淀粉对带鱼鱼糜凝胶品质的改善效果最好,在鱼糜中添加15%木薯淀粉时,鱼糜凝胶强度、硬度、粘聚性、弹性、咀嚼性、白度值、失水率和凝胶溶解度分别为886.176 g·cm、4 879.56g、0.67、0.87、2 888.86、60.07、5.84%、49.47%。因此,添加15%的木薯淀粉能有效改善带鱼鱼糜凝胶品质。本试验结果为高品质鱼糜制品生产提供了科学依据。     

超高压处理对大黄鱼鱼糜水分状态和蛋白质结构的影响

为了研究超高压处理大黄鱼鱼糜的凝胶特性,该文利用低场核磁共振、拉曼光谱研究了水浴加热和超高压处理鱼糜凝胶化过程中水分存在状态和蛋白质结构的变化,并分析了它们和鱼糜凝胶特性指标的相关性。结果表明,与水浴加热处理相比,超高压处理能改善鱼糜凝胶特性,使其保水率、弹性、内聚性增大（P<0.05）,硬度下降（P<0.05）。但随压力增大,鱼糜的内聚性、弹性、咀嚼性呈下降趋势（P<0.05）,保水率变化不显著（P>0.05）;低场核磁共振分析显示超高压使鱼糜自由水组分消失,不易流动水的流动性增强（P<0.05）,结合水的含量增加（P<0.05）;拉曼光谱分析显示超高压使鱼糜蛋白α-螺旋含量显著增加（P<0.05）,无规卷曲和β-转角含量显著下降（P<0.05）,三级结构也发生变化;相关性分析表明,蛋白质结构、水分状态及含量与鱼糜的质构、保水率之间存在特定相关性。说明不同处理条件下,鱼糜的蛋白质结构和水分状态发生改变,从而表现出相应的质构、保水率等凝胶特性。以上结果可为鱼糜凝胶特性的评价及改进提供检测方法及理论依据。     

大豆胰蛋白酶抑制剂对带鱼鱼糜蛋白降解及其凝胶特性的影响

为提高带鱼鱼糜制品品质,以鱼糜蛋白组成、TCA-溶解肽含量及其凝胶强度等为指标,研究大豆胰蛋白酶抑制剂(STI)对带鱼鱼糜蛋白降解及其凝胶特性的影响。结果表明,带鱼鱼糜蛋白的降解与温度显著相关,随温度升高,肌原纤维蛋白重链(MHC)逐渐降解,TCA-溶解肽含量增加,在70℃时达到最高值(1.3μmol酪氨酸·g~(-1))。添加STI能够一定程度抑制带鱼鱼糜凝胶劣化样品和凝胶化样品中肌原纤维蛋白的降解,降低TCA-溶解肽含量。当STI添加量为0.10‰时,凝胶劣化样品和凝胶化样品的TCA-溶解肽含量达到最低值,分别为0.13和0.30μmol酪氨酸·g~(-1),凝胶强度达到最高值,分别为414.74 g·mm和1 262.28 g·mm,而失水率分别下降为5.44%和3.76%;电镜微观结构显示,此时凝胶结构更致密、均匀,但凝胶白度值轻微下降。因此,STI可有效提高带鱼鱼糜制品品质,从而为生产高品质的带鱼鱼糜制品提供参考和依据。     

荞麦、玉米、马铃薯淀粉凝胶特性的试验研究(英)

利用电子万能材料试验机对荞麦、玉米、马铃薯淀粉的力学特性进行了研究。结果表明：在一定范围内，随着淀粉乳浓度的增加，荞麦、玉米、马铃薯的凝胶强度、弹性模量和凝胶弹性呈线性增加，但凝胶弹性变化较小；同一淀粉乳浓度下凝胶强度由高到低顺序为马铃薯淀粉＞玉米淀粉＞荞麦淀粉，弹性模量为马铃薯淀粉＞玉米淀粉＞荞麦淀粉，凝胶弹性为荞麦淀粉＞玉米淀粉＞马铃薯淀粉。在淀粉乳浓度为20％时，随着NaCl浓度增加，3种淀粉的凝胶强度均有一定程度增强。在同一NaCl浓度下，其凝胶强度为马铃薯淀粉＞玉米淀粉＞荞麦淀粉，弹性模量为马铃薯淀粉＞玉米淀粉＞荞麦淀粉，对凝胶弹性的影响不大。     

大豆蛋白热变性程度对速溶豆腐花粉凝胶成型的影响

针对速溶豆腐花粉的制备工艺中需要对大豆进行热处理,热处理过程中大豆蛋白的热变性程度对豆腐花粉凝结的凝胶强度与凝结所需的时间具有显著影响,而现在速溶豆腐花粉的工业生产中还没有对豆浆热处理程度较为合适的标准。该文以大豆、大豆分离蛋白(soybean protein isolate,SPI)、大豆球蛋白(glycinin,11S)、β-伴大豆球蛋白(beta-conglycinin,7S)为原料,研究大豆蛋白热变性程度对速溶豆腐花粉凝胶成型的影响。研究表明11S比7S更难发生完全变性,SPI中的7S和11S比单独存在的7S、11S更难发生完全变性。传统制备方式、前热处理后喷雾干燥或冷冻干燥制备方式、先喷雾干燥或冷冻干燥后热处理制备方式对豆腐花凝结成型影响不同,其中传统方式制备的豆腐花凝胶效果最好,先干燥后热处理制备的豆粉凝胶效果比前热处理后干燥的豆粉好,引起豆腐花凝胶强度差异的主要原因是大豆蛋白中7S和11S热变性程度不同。制备同一凝胶强度的豆腐花,热处理温度越低,所需的热处理时间越长;制备高凝胶强度的豆腐花比制备低凝胶强度的豆腐花所能进行的热处理温度与时间范围小。大豆蛋白的7S处于完全变性而11S处于未完全变性的状态时,适合制备速溶豆腐花粉的大豆蛋白变性程度应控制热处理温度与时间范围为80℃时热处理20~65 min,85℃时热处理15~50 min,90℃时热处理10~35 min,95℃时热处理5~20 min。该研究结果为调控速溶豆腐花粉的凝胶特性提供理论依据。     

单细胞凝胶电泳检测PFOS和PFOA对三角涡虫核DNA的损伤作用

全氟辛烷磺酸盐（PFOS）和全氟辛烷磺酸（PFOA）被使用50多年,污染已十分广泛,但它们的毒性机制仍不明确,尤其是基因毒性方面。本实验以三角涡虫为研究对象,采用单细胞凝胶电泳（single cell gel electrophoresis,SCGE,彗星实验）技术,探究PFOS和PFOA对细胞核DNA的损伤作用。结果显示PFOA能破坏核DNA,使其断裂,但PFOS不能破坏核DNA。另外,我们进一步提取纯化的大肠杆菌DNA与PFOS和PFOA共同孵育,以验证我们的实验结果,结果显示体外DNA实验与单细胞凝胶电泳检验结果一致。     

添加剂对秘鲁鱿鱼肌原纤维蛋白热诱导凝胶特性的影响

为探讨添加剂及其添加量对秘鲁鱿鱼肌原纤维蛋白热诱导凝胶特性的影响,以秘鲁鱿鱼为原料,在单因素试验基础上选择4种添加剂(壳聚糖、转谷氨酰胺酶、卡拉胶、海藻酸钠),通过响应面法建立肌原纤维蛋白凝胶硬度和添加剂用量之间的响应模型。结果表明,4种添加剂的最适添加量分别为:壳聚糖0.40%、转谷氨酰胺酶0.50%、卡拉胶0.90%、海藻酸钠0.25%,在此条件下秘鲁鱿鱼肌原纤维蛋白热诱导凝胶硬度达最大值859.85 g,保水性为96.34%。此复合添加剂能显著改善秘鲁鱿鱼肌原纤维蛋白的凝胶特性。研究结果为生产高品质的秘鲁鱿鱼凝胶制品提供了理论依据。     

电阻抗分析法在海藻酸钙胶囊干燥中的应用

海藻酸钙胶囊是由大分子、水分子和离子组成的复杂网络结构,其水分含量很高(约3500%,以干基计)。在海藻酸钙胶囊干燥过程中,用常规分析方法确定干燥机理和硬化反应关键点等比较困难。电阻抗分析法在实际分析中有很多优点,该研究用于监控海藻酸钙胶囊的干燥进程。确定了电阻抗分析法的测定条件,测定并分析了几种干燥过程中电阻抗特性的变化     

Application of isozyme data to the management of the United States national Brassica oleracea L. genetic resources collection

Summary Management of a genetic resources collection is more effective if a curator can accurately identify genotypes and accessions as well as assess intraspecific genetic relationships and the genetic structure of species. Consequently, a study was conducted to determine whether data from starch gel electrophoresis of a specific set of isozymes from plants of Brassica oleracea (cole crops) would be useful in answering four questions the answers to which are essential for effective curatorial activities: Can individual plants be identified? Can specific accessions be identified? What are the genetic relationships among botanical varieties within B. oleracea? What is the genetic structure of the species B. oleracea? Six loci from 4 enzyme systems (LAP, PGD, PGI, and PGM) were analyzed. Individuals and accessions could not usefully be identified using these isozymes, but genetic relationships within and genetic structure of the species were easily determined, resulting in specific recommendations for improving collection management. As expected, highly selected commercial lines exhibited less diversity than average, and so may be of limited value when trying to maximize diversity with a minimum number of accessions. In contrast, landraces and weakly selected lines are more diverse than average, and thus are useful in maximizing per accession diversity. Not only was 93% of the genetic variability in B. oleracea found among accessions and a mere 7% among varieties, but also a cluster analysis showed that accessions of a single botanical variety are often more similar to those of a different variety than to each other. These results suggest that in order to create a genetic resources collection of B. oleracea that faithfully represents the diversity in the species, a curator should assemble a broad array of accessions originating from diverse agroecological niches, having different levels of improvement, and representing all botanical varieties.Abbreviations LAP Leucine amino peptidase - PGD 6-Phosphogluconate dehydrogenase - PGI Phosphoglucoisomerase - PGM Phosphoglucomutase - RAPD Random amplified polymorphic DNA - RFLP Restriction fragment length polymorphism - UPGMA Unweighted pair-group method using arithmetic averages     

小麦易位系麦醇溶蛋白的电泳分析

本文利用聚丙烯酰胺凝胶电泳(PAGE)技术分析了3个小麦易位系及其亲本的麦醇溶蛋白组分,进一步明确了它们的亲缘关系和遗传组成。     

Application of polymerase chain reaction-denaturing gradient gel electrophoresis for comparison of direct and indirect extraction methods of soil DNA used for microbial community fingerprinting

 We used polymerase chain reaction-denaturing gradient gel electrophoresis (PCR-DGGE) to compare bacterial community patterns obtained with target DNA extracted from a soil by direct and indirect methods. For this purpose, two direct extraction methods, i.e. cell lysis by bead beating and cell disruption by grinding in liquid N, and two indirect methods, i.e. cell extraction followed by DNA extraction, and combined RNA/DNA extraction from the bacterial cell fraction, were performed. Crude extracts were purified and amplified using universal bacterial primers. PCR products were then analysed by DGGE, and similarity between the profiles obtained was determined by unweighted pair group with mathematical averages clustering. The results showed clear profiles that presumably represented the dominant bacterial fractions in the samples. The profiles generated by all four methods were similar, indicating that the methods were of approximately equal efficiency in the extraction of target DNA representative of the soil bacterial community. However, the patterns of clustering also indicated that different populations of bacteria could be detected in the same soil using different soil DNA extraction methods. The application of two dilution levels of DNA in PCR-DGGE showed that the most stable profile of the soil bacterial community could be generated by the direct methods. The indirect methods gave clustered profiles at both dilution levels. It is likely that these methods extracted DNA from a major, easily desorbed, bacterial fraction, consisting of low-density populations. PCR-DGGE was found to be a suitable technique with which to assess differences in methods for DNA extraction from soil, which can be further used for the determination of microbial community diversity at the molecular level. Received: 22 June 1999     

螺杆挤压生产高凝胶强度的低温溶解江蓠属琼脂

为了获得在60℃低温溶解且凝胶强度高的琼脂粉,以中国产的江蓠琼脂粉为原料,采用双螺杆挤压加工技术予以改性,研究了加工温度、水料比、螺杆转速和模孔直径对琼脂低温溶解性质的影响,并采用Box-Behnken设计及响应面分析法优化其加工工艺参数。结果表明,加工温度对琼脂低温溶解性影响显著;加工温度和水料比对琼脂凝胶强度影响显著,且加工温度和水料比具有互作效应。经优化后,当加工温度为126℃、水料比为0.37mL/g、螺杆转速为150r/min和模孔直径为6mm时,凝胶强度(质量浓度1%)为683.6g/cm2。产品在60℃具有良好的溶解性和凝胶强度,节约了工业生产中溶解琼脂所需的能源,使温度敏感的物质与琼脂的共同应用成为可能,而且满足不同产品对凝胶强度的需求,为工业生产提供参考。     

Effects of coated and non-coated ZnO nano particles on cucumber seedlings grown in gel chamber

Zinc oxide-engineered nanoparticles (ZnO ENPs) have received the most attention in recent years. This increasing interest has been directed towards studying the environmental fate and effects of ZnO ENPs on ecological terrestrial species. In this study, ZnO NPs were synthesized by atmospheric pressure solution evaporation method and were coated or uncoated with humic acid (HA). The root uptakes of uncoated and HA-coated ZnO NPs and zinc (Zn) were investigated by gel-grown cucumber. Two ZnO levels (1 and 200 µM) were applied in the form of coated (T₃) and non-coated (T₂) NPs or bulk particles (T₁). The results showed that coating NPs by HA increases zeta potential of NPs and decreases their aggregation size due to the increase in the repulsion forces among the particles. Addition of 1 mgL^?1 ZnO into gel chamber enhanced root and shoot biomass; however, the shoot growth was higher in the presence of NPs compared to its bulk counterpart. Moreover, greater phytotoxicity of ZnO from the source of NPs than bulk particles in shoot was observed. Scanning electron microscopy results showed a clear evidence of the penetration of NPs into root cells.