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1.
研究了青鳞鱼蛋白复合酶控制水解产物的功能特性。结果表明，复合酶控制水解能够显著地改善水解物的溶解性、乳化活力及起泡性能。水解物在pH2．0～10．0范围内其NSI为89．3％～98．5％，且在酸性范围NSI高于碱性范围；在酸性pH内水解物的乳化活力都高于112m^2／g，随着DH的增加，最大乳化活力出现的pH范围更宽广，但水解却降低了乳化稳定性。蛋白质质量分数为1％～5％时，FP随质量分数的增加而增加；泡沫形成后，未水解的蛋白质具有最高的稳定性，DH为8．4％的水解物具有最高的稳定性。  相似文献   

2.
青鳞鱼蛋白复合酶控制水解动力学模型的研究   总被引：1，自引：0，他引：1  
在假设复合酶恒温控制水解动力学遵循内切酶限制水解动力学历程的前提下 ,采用实验方法求出了复合酶恒温控制水解动力学模型。结果表明 ,复合酶对青鳞鱼蛋白进行控制水解的动力学模型为 :R =(0 .315 4e0 - 0 .0 186s0 )exp(- 0 .170DH) ,DH =5 .882ln[1+(0 .0 5 36 2e0 /s0 -0 .0 0 32 )t];其酶失活常数Kd=0 .0 5 36min- 1;水解反应能够顺利进行的条件是 :e0 /s0 >c0 ,常数c0 =5 .90× 10 - 2 。验证实验证明 ,根据复合酶恒温控制水解动力学模型得到的理论DH与实际DH基本吻合 ,该动力学模型具有很强的实用价值。  相似文献   

3.
以南海低值鱼蛋白为原料,采用木瓜蛋白酶和风味酶的复合酶水解得到多肽水解物(HP),并制备多肽-铁(Ⅱ)螯合物,对螯合工艺及螯合产物的结果及抗氧化和抗菌功能特性进行了初步研究。结果表明:1)水解度为5%的多肽与铁(Ⅱ)螯合效果最佳,螯合率为94.15%;2)化学分析及红外光谱表明活性肽与亚铁离子螯合并形成稳定结构的螯合物;(3)经过50%乙醇(体积分数)沉淀的螯合铁具有明显的抗氧化活性,其抗氧化作用相当于维生素E的90%,经过80%乙醇(体积分数)沉淀的螯合物具有显著的抗枯草牙孢杆菌和金黄色葡萄球菌活性,其抑菌圈均直径为13mm。  相似文献   

4.
【目的】制备壳聚糖CS-大豆蛋白SPI-百里香酚Thy乳液(CST),探究其对大口黑鲈(Micropterus salmoides)的保鲜效果。【方法】设置大豆蛋白添加量分别为1.6%、2.4%、3.2%、4.0%、4.8%(质量分数),制备不同大豆蛋白浓度的壳聚糖-大豆蛋白-百里香酚复合乳液(其中壳聚糖质量分数为0.5%,百里香酚质量分数为1.0%),研究其结构、乳化能力和乳液稳定性等。将经最佳配比CST乳液处理后的大口黑鲈肉块与未进行处理的对照组在10℃下贮藏,检测贮藏过程中鱼肉pH、挥发性盐基氮和菌落总数等指标,验证乳液的保鲜效果。【结果】在大豆蛋白质量分数为3.2%时,CST乳液乳化稳定性指数(ESI)和乳液乳化活性指数(EAI)达到最大值,分别为(0.92±0.18)%和(8.85±0.13)m2/g;此时,粒径较小,为(13.05±0.05)μm;Zeta-电位较高,达到(39.64±0.83)mV;表面疏水性指数最大,美拉德反应物生成指数最高,内源性荧光强度最大,乳液稳定指数最佳。乳液处理后的鱼肉pH、挥发性盐基氮和菌落总数结果远优于对照组,在10℃...  相似文献   

5.
以罗非鱼鱼鳞胶为原料,制备对血管紧张素转换酶(ACE)有抑制活性的降血压肽。以水解度(DH)及ACE抑制率为指标,筛选水解鱼鳞胶的最适酶种,并对其水解工艺条件进行优化;采用超滤技术对所制备的降血压肽进行分离纯化,比较不同组分的ACE抑制率,测定高ACE抑制率组分的氨基酸组成,并运用MALDI-TOF-MS法分析其分子质量分布。结果表明,复合蛋白酶是水解鱼鳞胶最适酶种,在50℃、pH7.5、料液质量体积比1∶5、酶与底物质量比(mE/mS)1.5%条件下,酶解6 h,酶解液的ACE抑制作用最强,其水解度DH 73%,ACE的抑制率76.15%。酶解液经超滤分离所获得的分子质量小于2 000 u的组分对ACE抑制率最高,达83.15%;该组分的氨基酸主要含有Gly和Pro,含量分别为22.04%和11.40%;该组分分子质量范围为1 300~2 000 u。  相似文献   

6.
对青鳞鱼肌肉蛋白质风味酶的水解条件及产物进行了详细研究.正交试验结果表明,在2 h内,风味酶对肌肉蛋白质的最适宜条件为酶浓度180×103IU/g、45 ℃、pH7.0 及底物浓度3.3%;产物分析提示风味酶对胱氨酸、缬氨酸、蛋氨酸、亮氨酸、苯丙氨酸、组氨酸及酪氨酸结合的肽键具有最高的特异性,它还具有形成新的肽键的能力;在10～180 min内任一时刻的水解产物经过离心,0.45 μm-和0.22 μm过滤而得到的水解物的分子大小没有明显的差异,同时10～180 min内任一时刻的离心水解产物间的平均相对分子质量也没有明显差异.研究结果为青鳞鱼的综合利用提供了基础理论依据.  相似文献   

7.
比较了南海产青干金枪鱼(Thunnus tonggol)、圆鮀鲣(Auxis tapeinosoma)和鲣(Katsuwonus pelamis)的普通肉、暗色肉营养成分。结果表明,南海产青干金枪鱼、圆鮀鲣、鲣的普通肉粗蛋白(干基)质量分数依次为85.29%、87.72%、84.11%,暗色肉蛋白质质量分数分别为75.34%、81.07%、75.35%。青干金枪鱼普通肉和暗色肉的粗脂肪(干基)质量分数为6.50%和9.38%,圆鮀鲣为2.00%和7.38%,鲣为4.94%和10.26%。暗色肉蛋白质质量分数分别为20.62%、22.03%、21.86%。青干金枪鱼、圆鮀鲣及鲣普通肉和暗色肉的第一限制性氨基酸均为缬氨酸,必需氨基酸评分(AAS)分别为94和82,96和89,90和89;普通肉的蛋白质含量、必需氨基酸含量及AAS均高于暗色肉,说明普通肉的蛋白营养价值高于暗色肉。3种金枪鱼的普通肉、暗色肉中均含有许多不饱和脂肪酸,占总脂肪的37%~58%。DHA+EPA含量占总脂肪的17%~28%,且暗色肉中含量高于普通肉。3种金枪鱼的普通肉和暗色肉中均含有丰富的Ca、Fe、Zn等矿物元素。总体评价,南海3种金枪鱼普通肉、暗色肉均营养价值丰富。  相似文献   

8.
为解决化学驱油体系中无机碱引起地层黏土膨胀、注采系统结垢等问题,充分发挥碱的作用,降低由传统无机碱带来的不利影响,以乙二胺(EDA)作为碱剂,与十二烷基苯磺酸钠(SDBS)复配,与孤东油田原油制备乳状液,考察温度、含水率、SDBS及EDA单独使用和复配使用时的质量分数、乙醇助剂等因素对乳状液的影响,使用析水率和微观结构观测相结合的方法分析乳状液的稳定性.结果表明,当温度低于70℃时,随着温度的升高,原油黏度下降很快;乳状液黏度随含水率的增大先升高后降低,含水率为50%时的黏度最高;50℃、油水质量比为1∶1时,质量分数不超过0.100%的SDBS和EDA单独使用时乳状液的析水率达到50%以上,乳化油滴数量较少;二者复配使用时乳状液的析水率可降至38%,且乳化油滴数量多,稳定性增强;质量分数为0.100%的乙醇助剂的加入可进一步使乳状液的析水率降至30%.  相似文献   

9.
以南海低值鱼蛋白为原料，采用木瓜蛋白酶和风味酶的复合酶水解得到多肽水解物（HP），并制备多肽．铁（Ⅱ）螯合物，对螯合工艺及螯合产物的结果及抗氧化和抗菌功能特性进行了初步研究。结果表明：1）水解度为5％的多肽与铁（Ⅱ）螯合效果最佳，螯合率为94．15％；2）化学分析及红外光谱表明活性肽与亚铁离子螯合并形成稳定结构的螯合物；（3）经过50％乙醇（体积分数）沉淀的螯合铁具有明显的抗氧化活性，其抗氧化作用相当于维生素E的90％，经过80％乙醇（体积分数）沉淀的螯合物具有显著的抗枯草牙孢杆菌和金黄色葡萄球菌活性，其抑菌圈均直径为13mm。  相似文献   

10.
【目的】为了提高石斑鱼加工副产物的生物价值,对石斑鱼头中抗氧化活性物质进行分离与功能性质分析。【方法】以珍珠龙胆石斑鱼头为原料,采用生物酶解法,以水解度和DPPH自由基清除率为指标,通过单因素试验和响应面法优化酶解工艺;酶解产物经不同分子质量的超滤膜进行分离,对分离各级分的体外抗氧化活性与功能性质进行研究。【结果】石斑鱼头酶解产物的最佳制备条件是:风味蛋白酶添加量3 000 U/g,在pH 7.0,酶解温度为45℃、底物质量浓度300mg/mL下酶解4.5h,得到的石斑鱼头粗酶解产物的水解度为(20.27±1.28)%。分子质量3 ku的酶解产物(EHH-1)蛋白质质量分数为(13.18±1.17)%,抗氧化活性最显著,其对DPPH自由基、羟自由基、超氧阴离子自由基清除作用的IC_(50)值分别为0.35、4.60、0.46 mg/mL;在pH4.0～8.0之间均具有较好溶解性,氮溶指数达到(75.08～87.50)%,热稳定性达到(70.00～82.00)%,乳化活性为(23.52～37.45)m~2/g。【结论】石斑鱼头酶解产物分子质量3 ku的超滤级分具有较强的抗氧化性与良好的功能性质,在天然抗氧化剂和食品加工领域有潜在的利用价值。  相似文献   

11.
In this study, the Alaska pollock protein isolate(APPI) was hydrolyzed by Neutrase for 20, 40, 80, 120, 160, 200, and 240 min. Hydrolysates with different molecular weights were produced and they were named as H1–H7. Furthermore, the effects of hydrolysis on the average molecular weights, functional properties(solubility, oil-holding capacities, foaming activities, and emulsifying properties), and antioxidant activities(1, 1-diphenyl-2-picrylhydrazyl, superoxide, and hydroxyl free radical-scavenging activities) were determined. It was found that when the degree of hydrolysis(DH) increased, the average molecular weights of the hydrolysates decreased significantly. The functional properties of APPI were also significantly improved. The hydrolysates of APPI exhibited better solubility, emulsifying activities, and foaming activities. Hydrolysates with low molecular weights(1 kDa) had better solubility, oil-holding capacities, and emulsifying activities, while hydrolysates with higher molecular weights(1 kDa) had better foaming activities. In addition, the hydrolysates exhibited excellent antioxidant properties, while the inhibition values of 1, 1-diphenyl-2-picryl hydroxyl(DPPH), superoxide, and hydroxyl free radical-scavenging activities, were 85.22%, 53.56%, and 75.00% respectively, when the concentration of the hydrolysates was 5.0 mg mL~(-1). The lower the average molecular weight was, the higher was the antioxidant activity. These results indicated that hydrolysis with Neutrase is an effective method for improving the functional and antioxidant properties of APPI. The hydrolysates of APPI displayed great potentials to be used as natural antioxidants in protein-rich aqueous foods such as nutrient supplements and sports beverages.  相似文献   

12.
为了优选良好储层适应性起泡剂及评价注入参数和封堵性能,通过实验静态评价泡沫高度最高、持续时间最长、表面张力最低的起泡剂.模拟真实储层环境,采用动态方法优选泡沫气液比、起泡剂质量分数、注入参数和在多孔介质中生成泡沫的封堵有效期,其中气液比对储层压力比较敏感,优选时需要设置回压;质量分数优选可以在无回压的条件下进行.结果表明:氮气泡沫在多孔介质中的封堵有效期远大于在体相中的有效期.采用静态和动态相结合的方法对氮气泡沫封堵性能进行评价是合理的,可以为矿场应用提供指导.  相似文献   

13.
Preparation of Fe^2＋ chelate of fish protein hydrolysate （Fe-FPH） obtained from low value fish proteins was introduced and its bioactivity was studied by compound enzymolysis. The optimum conditions for hydrolysate chelating Fe^2＋ are DH （degree of hydrolysis） at 5%, pH 7.0, 20℃ and 15 min chelating time for FM （material not being defatted）. Four types of Fe-FPH including CA （deposit after chelating）, CB （deposit in 50% of absolute ethanol solution）, CC （suspended deposit in 80% of absolute ethanol solution）, and CD （bottom deposit in 80% of absolute ethanol solution） were fractionated with absolute ethanol from FM. Structural analysis through infra-red spectrum revealed that Fe^2＋ was combined strongly with amino-group and carboxyl-group in each chelate and each Fe^2＋ could form two five-member ring structures. All of the four chelates were shown more significant antioxidative activity and can be used as natural hydrophobic and hydrophilic antioxidant. Among all the chelates, the CB possesses the most effective antioxidative activity at 92% as high as that of a-tocopherol. Among all Fe-FPHs, only CD showed the most effective antibacterial activity against Escherichia coli, Staphylococcus aureus, Salmonella typhi, and Bacillus subtilis and can be used as natural antibacterial. It provides a more effective way for utilization of low value fish proteins and key information of Fe-FPH as additive in food industry.  相似文献   

14.
Giant red sea cucumber (Parastichopus californicus) is an under-utilized species due to its high tendency to autolysis.The aim of this study was to evaluate the functional properties of collagen hydrolysates from this species.The degree of hydrolysis (DH),amino acid composition,SDS-PAGE,emulsion activity index (EAI),emulsion stability index (ESI),foam expansion (FE),and foam stability (FS) of hydrolysates were investigated.The effects of pH on the EAI,ESI FE and FS of hydrolysates were also inves-tigated.The results indicated that the β and α1 chains of the collagen were effectively hydrolyzed by trypsin at 50℃ with an En-zyme/Substrate (E/S) ration of 1:20 (w:w).The DH of collagen was up to 17.3% after 3 h hydrolysis with trypsin.The hydrolysates had a molecular weight distribution of 1.1 17 kDa,and were abundant in glycine (Gly),proline (Pro),glutamic acid (Glu),alanine (Ala) and hydroxyproline (Hyp) residues.The hydrolysates were fractionated into three fractions (< 3 kDa,3 10 kDa,and > 10 kDa),and the fraction of 3 10 kDa exhibited a higher EAI value than the fraction of > 10 kDa (P<0.05).The fraction of > 10 kDa had higher FE and FS values than other fractions (P<0.05).The pH had an important effect on the EAI,ESI,FE and FS.All the fractions showed undesirable emulsion and forming properties at pH 4.0.Under pH 7.0 and pH 10.0,the 3 10 kDa fraction showed higher EAI value and the fraction of > 10 kDa showed higher FE value,respectively.They are hoped to be utilized as functional ingredients in food and nutraceutical industries.  相似文献   

15.
Improvement in the osmoregulation capacity via nutritional supplies is vitally important in shrimp aquaculture.The effects of dietary protein levels on the osmoregulation capacity of the Pacific white shrimp(L.vannamei) were investigated.This involved an examination of growth performance,glutamate dehydrogenase(GDH) and Na+-K+ ATPase mRNA expression,,and GDH activity in muscles and gills.Three experimental diets were formulated,containing 25%,40%,and 50% dietary protein,and fed to the shrimp at a salinity of 25.After 20 days,no significant difference was observed in weight gain,though GDH and Na+-K+ ATPase gene expression and GDH activity increased with higher dietary protein levels.Subsequently,shrimp fed diets with 25% and 50% dietary protein were transferred into tanks with salinities of 38 and 5,respectively,and sampled at weeks 1 and 2.Shrimp fed with 40% protein at 25 in salinity(optimal conditions) were used as a control.Regardless of the salinities,shrimp fed with 50% dietary protein had significantly higher growth performance than other diets;no significant differences were found in comparison with the control.Shrimp fed with 25% dietary protein and maintained at salinities of 38 and 5 had significantly lower weight gain values after 2 weeks.Ambient salinity change also stimulated the hepatosomatic index,which increased in the first week and then recovered to a relatively normal level,as in the control,after 2 weeks.These findings indicate that in white shrimp,the specific protein nutrient and energy demands related to ambient salinity change are associated with protein metabolism.Increased dietary protein level could improve the osmoregulation capacity of L.vannamei with more energy resources allocated to GDH activity and expression.  相似文献   

16.
Gelatin from the sea cucumber(Paracaudina chinens var.) was hydrolyzed by bromelain and the hydrolysate was found to have a high free radical scavenging activity. The hydrolysate was fractionated through an ultrafiltration membrane with 5 kDa molecular weight cutoff(MWCO). The portion(less than 5 kDa) was further separated by Sephadex G-25. The active peak was col-lected and assayed for free radical scavenging activity. The scavenging rates for superoxide anion radicals(O2·-) and hydroxyl radi-cals(·OH) of the fraction with the highest activity were 29.02% and 75.41%,respectively. A rabbit liver mitochondrial free radical damage model was adopted to study the free radical scavenging activity of the fraction. The results showed that the sea cucumber gelatin hydrolysate can prevent the damage of rabbit liver and mitochondria.  相似文献   

17.
The present study investigated the removal of inorganic arsenic from Pinctada martensii enzymatic hydrolysate through unmodified resin (D296) and Zr(IV)-loaded chelating resin (Zr-D401). By loading Zr to macroporous chelating resin D401, the as exchange adsorption active sites are generated. This transforms D401 from a material that does not have the arsenic adsorption capacity into a material that has excellent arsenic exchange adsorption capacity. The static adsorption experiments were conducted to investigate the optimal removal condition for D296 and Zr-D401. The experimental results show that: the optimum condition for D296 is that T= 25°C, pH = 5, resin additive amount = 1 g (50 mL)?1, and contact time = 10 h, the corresponding arsenic removal rate being 65.7%, and protein loss being 2.33%; the optimum condition for Zr-D401 is that T=25°C, pH = 8, resin additive amount = 1 g (50 mL)?1, and contact time=10 h, the corresponding arsenic removal rate being 70.3%, and protein loss being 4.65%. These results show that both of the two resins are effective in arsenic removal for preserving useful substance. Our research provides scientific evidence and advances in the processing technology for heavy metal removal in shellfish.  相似文献   

18.
稠油蒸气—泡沫驱不同油藏区域流体的流变特征   总被引：3，自引：2，他引：1  
针对稠油蒸气-泡沫驱蒸气腔驱油区泡沫油体系、热水冷凝区热水油体系,通过模拟实际油藏温度压力条件,利用高温高压流变仪,在0～600s-1剪切速率范围内,研究蒸气相饱和度、泡沫剂质量分数、温度和蒸气干度对泡沫油体系流变特征的影响;在0～100s-1剪切速率范围内,研究热水相饱和度、泡沫剂质量分数和温度对热水油体系流变特征的影响.结果表明,泡沫油体系和热水油体系均为假塑性流体,可用幂律模型来描述,并且随着蒸气相饱和度和泡沫剂质量分数升高,泡沫油体系非牛顿性增强;随着温度和蒸气干度增大,泡沫油体系越接近为牛顿流体;随着热水相饱和度和温度升高,热水油体系越接近为牛顿流体;随着泡沫剂质量分数增加,热水油体系非牛顿性增强.  相似文献   

19.
Gelatin from the sea cucumber （Paracaudina chinens var.） was hydrolyzed by bromelain and the hydrolysate was found to have a high free radical scavenging activity. The hydrolysate was fractionated through an ultrafiltration membrane with 5 kDa molecular weight cutoff （MWCO）. The portion （less than 5 kDa） was further separated by Sephadex G-25. The active peak was collected and assayed for free radical scavenging activity. The scavenging rates for superoxide anion radicals （O2·^-） and hydroxyl radicals （·OH） of the fraction with the highest activity were 29.02% and 75.41%, respectively. A rabbit liver mitochondrial free radical damage model was adopted to study the free radical scavenging activity of the fraction. The results showed that the sea cucumber gelatin hydrolysate can prevent the damage of rabbit liver and mitochondria.  相似文献   

20.
Ocean acidification leads to changes in physiological and immune responses of bivalves, but the eff ect on the immune enzyme activities of the Manila clam, R uditapes philippinarum, when the pH is lower than the normal value has not been studied in detail. In this study, experiments were conducted to determine how pH(7.4, 7.7, 8.0) affects the immune enzyme activities in the gill and hemocytes of the Manila clam. Membrane stability and phagocytosis increased with decrease of pH from 8.0 to 7.7 and then decreased at pH 7.4. The total protein content in the hemocytes and gills decreased with decreasing pH. Lysozyme content in the hemocytes increased with decreasing pH, and the diff erences were significant among the different pH groups(P 0.05). Adenosine triphosphatase activity at pH 7.4 was significantly higher than in the other two groups, but no significant diff erence was observed between pH 7.7 and 8.0. Catalase activity decreased from pH 8.0 to 7.7 and then increased at pH 7.4, and the dif ferences were significant among the experimental groups( P 0.05). These findings provide valuable information about the immune response of R. philippinarum to reduced water pH and insights for future research investigating exposure of bivalves to elevated CO_2 conditions.  相似文献   

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