齐口裂腹鱼骨胶原蛋白超声波辅助提取工艺及其特性研究

为提高鱼骨胶原蛋白提取效率,在超声波辅助酸法的工艺条件下,采用单因素及正交试验研究齐口裂腹鱼骨胶原蛋白提取方法;采用SDS-PAGE电泳、紫外扫描、氨基酸分析、热变性温度测定分析分离纯化后的胶原蛋白。结果表明,超声波预处理显著提高了齐口裂腹鱼骨胶原蛋白提取得率,最优条件为:提取温度30~℃,液料比751(mL/g),超声波预处理时间20min,提取时间48h,该条件下胶原蛋白得率为6.91%,纯度为89.74%;SDS-PAGE结果显示,齐口裂腹鱼骨胶原蛋白由α1、α2和β链组成,属Ι型胶原蛋白的特征;紫外扫描结果显示,最大吸收峰的波长在220~232nm;齐口裂腹鱼骨胶原蛋白主要由甘氨酸组成,占总氨基酸含量的31.21%,热变性温度为31.4~℃。     

提取温度对罗非鱼皮明胶理化性质的影响

本研究以罗非鱼皮为原料,研究在不同温度(30、40、50、60、70、80、90℃)下提取的明胶所表现的得率、凝冻强度、聚丙烯酰胺凝胶电泳分析、傅里叶红外光谱分析、热变性温度、流变性性能等理化特征。结果表明,提取温度对鱼皮明胶的紫外吸收无明显影响;随着提取温度的升高,鱼皮明胶的得率逐渐增大,在提取温度为60~80℃时差异不显著(p>0.05),在90℃达到最大值(62.60%±0.84%);聚丙烯酰胺凝胶电泳图谱显示,较低温度(30、40、50℃)下提取的鱼皮明胶由α₁、α₂、β 3条肽链组成,提取温度升高后电泳条带强度降低;提取温度为50℃时,罗非鱼皮明胶的凝冻强度最大,高达(884.33±26.76)g;FTIR光谱显示,不同温度下提取的鱼皮明胶在酰胺区都具有特征吸收峰,在光谱中显示出微小的差异;不同温度下提取的鱼皮明胶的热变性温度分别为(101.05±2.97)、(104.35±3.54)、(107.59±0.37)、(97.80±4.21)、(95.35±2.60)、(92.52±3.15)、(89.66±1.23)℃;提取温度通过改变明胶的分子量大小影响明胶溶液内部贮藏能量的多少,进而对明胶溶液的流变性能产生影响。     

加热方式和加热时间对鱼类明胶理化性质的影响

为探究加热方式和加热时间对鱼类明胶理化性质的影响,对加热明胶溶液的蛋白组成、粘度、流变性质和热稳定性,以及明胶凝胶的强度、质构（texture profile analysis,TPA）参数和微观结构进行分析和比较。结果显示,鱼类明胶溶液的粘度、流变性质及热稳定性随加热时间的增加而明显降低,但间歇加热明胶中这些性质的变化幅度均低于连续加热明胶。连续加热明胶至48 h时电泳图谱中β条带消失,96 h时α₁和α₂亚基明显降解,而当间歇加热明胶至96 h时β条带才消失。鱼类明胶形成的凝胶其强度和TPA参数随热处理时间的延长逐渐减小,但间歇加热明胶的凝胶形成能力优于连续加热明胶。扫描电子显微镜结果显示,连续加热的凝胶表面光滑平整,而间歇加热凝胶的结构更加粗糙且多孔隙。研究结果表明,间歇加热及加热时间小于12 h有利于减少明胶热降解。     

碱-酶预处理麦草工艺及其对成浆性能的影响

对麦草进行碱预处理和碱-酶预处理,然后对碱-酶预处理麦草进行烧碱-蒽醌法蒸煮.探讨了碱预处理时不同用碱量和反应温度对碱预处理后和碱-酶预处理后麦草得率和聚戊糖得率的影响和碱-酶预处理后进行烧碱-蒽醌法蒸煮纸浆的硬度及强度的变化.结果表明,随碱预处理用碱量增加和反应温度升高,麦草得率和聚戊糖得率均呈下降趋势;经碱-酶预处理的麦草采用烧碱-蒽醌法蒸煮后浆的硬度降低,抗张指数升高;当碱预处理用碱量为5％、反应温度为70℃时,碱-酶预处理后麦草得率为77.0％,聚戊糖得率为82.9％,烧碱-蒽醌法麦草浆卡伯值为10.0,抗张指数达49.3 N·m/g.     

胶原蛋白的提取及其纳米纤维的制备与表征

为提高羊皮中胶原蛋白的提取率和利用率，采用酸酶复合法提取羊皮胶原蛋白，再利用静电纺技术制备胶原基纳米纤维。以羊皮胶原蛋白提取率为评价指标，考察料液比、乙酸浓度、胃蛋白酶浓度和酶解时间四个因素对羊皮胶原蛋白提取效果的影响，确定单因素最优水平；在此基础上，采用正交试验设计对羊皮胶原蛋白提取的工艺条件进行优化，并通过紫外光谱扫描、红外光谱扫描、SDS-PAGE图谱和扫描电镜等生化技术探讨酶解过程对胶原蛋白结构性质的影响；然后将胶原蛋白和聚乳酸复合静电纺丝，制备得到胶原基纳米纤维。结果表明，酸酶复合法提取羊皮胶原蛋白最佳工艺为：料液比1:25 g/mL、乙酸浓度1.2 mol/L、胃蛋白酶用量1.0%、酶解时间72 h，在此条件下羊皮胶原蛋白提取率为38.42%±0.49%；紫外光谱扫描显示羊皮胶原蛋白于230 nm附近出现最大紫外吸收峰；红外光谱扫描、SDS-PAGE图谱分析表明羊皮胶原蛋白主要有α₁、α₂、β三种亚基成分组成，属于Ⅰ型胶原蛋白，且胶原蛋白的空间结构保留完整；扫描电镜直观表明了羊皮胶原蛋白的纤维网络结构保留较完整；静电纺丝得到的胶原...     

酸预处理时间对鲢鱼皮明胶理化性质的影响

本文探究了酸预处理时间对鲢鱼皮明胶理化性质的影响。结果发现,当酸预处理时间从10 min增加到80 min,鲢鱼皮的结构变得疏松,在热水浸提中β肽链等胶原高分子组分易发生降解,提取的明胶其羟脯氨酸含量从61个残基下降到43个残基/1000个氨基酸。不管酸预处理时间多长,提取的鲢鱼皮明胶其等电点均在p H 9.2附近,但长时间的酸处理会使明胶的黏度、凝胶性能和成膜性能下降。当酸预处理时间为10 min时,制备的明胶凝胶强度、膜的抗拉伸强度和断裂延伸率分别为242.67 g、28.24 MPa和65.52%。根据圆二色光谱扫描的结果,发现酸预处理时间对明胶二级结构没有明显的影响,但酸预处理时间越长,提取的明胶在干燥过程中越不易复性形成三股螺旋结构,结果导致成膜性能下降。     

黑木耳胶原蛋白结构性质研究

黑木耳是我国珍贵的药食兼用的胶质真菌，营养丰富，蛋白质含量较高，其他营养物质也较丰富，必需氨基酸种类齐全、组成合理，广泛应用于食品保健等方面。本研究以纯化后的黑木耳胶原蛋白为原料，利用氨基酸分析、紫外光谱、傅里叶红外光谱、圆二色谱、SDS-PAGE聚丙烯酰胺凝胶电泳、差示量热扫描(DSC)及扫描电镜对黑木耳胶原蛋白进行理化性质的研究。结果表明：黑木耳胶原蛋白甘氨酸含量占比较大，脯氨酸含量为8.4%、羟脯氨酸含量为5.2%；紫外吸收峰在221 nm附近出现最大吸收峰，较符合Ⅰ型胶原蛋白特征；红外光谱及圆二色谱推断其具有较完整的三股螺旋结构；在116 kDa、97.2 kDa处出现两条类似Ⅰ型胶原蛋白α₁链和α₂链的亚基条带；确定最佳变性温度为117.4℃，热稳定性较好；通过扫描电镜发现黑木耳胶原蛋白具有空间纤维网状结构。     

碳酸钠和盐酸法提取荞麦壳中水不可溶性膳食纤维的对比研究

为提高荞麦壳利用率并且探究最佳的提取条件及增加其利用形式,本文以荞麦壳为原料,分别采用碳酸钠浸泡法和盐酸酸提法对荞麦壳中的水不可溶性膳食纤维(IDF)进行提取。结果表明,碳酸钠提取荞麦壳IDF的最佳工艺为碱解温度60 ℃,Na₂CO₃质量分数为10%,碱解时间40 min,料液比为1:13 g/mL,荞麦壳IDF的得率为82.75%,膨胀力为6.87 mL/g,持水力为379.18%。HCl酸提法提取荞麦壳IDF的最佳工艺条件为pH为2,酸浸温度为60 ℃,酸提时间为100 min,料液比为1:15 g/mL。荞麦壳IDF的得率为86.00%,膨胀力5.92 mL/g,持水力为365.31%。在最佳工艺条件下,盐酸法提取的IDF得率略高于碳酸钠法,但碳酸钠法提取的IDF具有更好的膨胀力和持水力等水合性能。     

不同预处理方式对蔗渣半纤维素降解的影响

通过对蔗渣预处理底物主要组分和制浆特性以及预处理过程中糖组分变化的研究,分析比较了热水预处理、稀酸预处理和稀碱预处理三种预处理方式对蔗渣半纤维素降解的影响。结果表明,酸预处理对半纤维素脱出选择性最好,聚戊糖溶出率可达85.97%,在保温20min时蒸煮液中主要糖组分木糖的浓度达到最大,为64.05g/L;热水预处理与酸预处理作用类似,但其纤维素降解少、得率高,聚戊糖溶出率为63.82%,反应结束时木糖浓度最高为38.67g/L;碱预处理选择性最差,木素溶出多,蒸煮液糖浓度很低,不利于后续预处理液的分离利用。当然,三种预处理都能够提高底物的制浆性能,相对原料直接蒸煮,底物蒸煮所得纸浆的卡伯值降低了1/3,纸浆得率和黏度则有所提高。     

玉米秸秆中还原糖的预提取及其对制浆性能的影响

本研究通过碱（NaOH）和酸（HCl）预处理以提取玉米秸秆中的还原糖,采用扫描电子显微镜观察玉米秸秆预处理前后的形态变化,探究了预处理前后玉米秸秆的制浆性能及纸张强度性能。结果表明,在150℃,NaOH和HCl用量分别为6%,预处理时间120 min条件下,玉米秸秆的酸、碱抽提的还原糖（Trs）得率分别为34.2%和14.5%。其中,酸预处理玉米秸秆在碱用量为12%蒸煮时,纸浆得率最高,为48.1%。此外,酸和碱预处理后纸张撕裂指数分别降低了18%和13%,抗张指数也呈现下降趋势,分别降低了28%和16%,耐破指数分别降低了60%和41%。因此,预处理过程中半纤维素的损失会导致纸张强度性能降低。     

Characteristics of the gelatin extracted from Channel Catfish (Ictalurus Punctatus) head bones

Three gelatins were prepared from channel catfish head bones by hot water after the head was pretreated with alkali protease, quickly desalted by 0.4 mol/L HCl and soaked in 9 g/L Ca(OH)₂. The extraction conditions of gelatins were 5 °C, pH 4.0, 4 h, 82 °C, pH 2.5, 2 h and 90 °C, pH 3.0, 3 h, respectively. The studies showed there were many differences between these gelatins. The first head bone gelatin contained high content of imino residues and more high molecular weight proportions of β and γ components. Gel strengths of the second and third gelatins were 209 ± 7 g and 117 ± 5 g, lower than that of the first head bone gelatin (282 ± 11 g). Furthermore, the first head bone gelatin achieved the highest gelling and melting points. The first head bone gelatin showed strong ability of clarification when it was used to clarify apple juice. At the same time, the nutritional components of apple juice changed a little except Vitamin C.     

Sea bream bones and scales as a source of gelatin and ACE inhibitory peptides

Sea bream scales and bones were used as sources of gelatin. Scales gave a higher gelatin yield than bones pretreated with HCl or Alcalase. Demineralization with EDTA was effective especially in the case of scale gelatin that showed the lowest ash content. The pretreatment of bones with HCl led to an increase in the removal of minerals. The gel strength and viscoelastic properties of sea bream scale gelatins were higher than those of bone gelatins, and only slight differences were found between gelatin extracted from bones pretreated with HCl or Alcalase, although the amino acid profile was similar in the three gelatins. The gel strength of scale gelatins was higher than that of a commercial bovine gelatin used for comparative purpose (Bloom 200–220). When the scales gelatin was hydrolyzed with Esperase, a high ACE-inhibitory activity was found in the peptide fraction below 3 kDa, and the amount of this peptide fraction required to inhibit 50% of the ACE activity (IC₅₀) was around 60 μg/mL.     

Structural Characteristics of Tilapia (Oreochromis mossambicus) Bone Gelatin: Effects of Different Liming Methods

Fish bone is a good source of gelatin. In this study, gelatins were prepared from tilapia bone after the bone was pretreated with alkali protease, desalted immediately by 0.6 mol L^?1 HCl, and hydrolyzed by papain or limed by Ca(OH)₂. Gelatins extracted from papain-treated tilapia bone exhibited space structures similar to those of alkali-treated tilapia bone. Despite this similarity, many differences were observed between these gelatin samples. Compared with alkali-treated gelatin, papain-treated gelatins showed higher values for imino residue content, molecular weight proportion, bloom strength, and viscosity. The bloom strengths of the second and third papain-treated gelatins were 163 and 94 bloom, respectively, which were lower than the bloom strength of the first papain-treated gelatin (189 bloom). The viscosities of the three papain-treated gelatin samples were 4.18, 2.81, and 0.51 mPa.s^?1. The first papain-treated gelatin achieved the highest gelling (16 °C) and melting points (23.9 °C). The yields of the first (5.40%) and second (6.71%) papain-treated gelatins were higher than those of the alkali-treated gelatins (3.33 and 5.76%, respectively). However, the yield of the third papain-treated gelatin (2.27%) was lower than that of the third alkali-treated gelatin (5.42%). More importantly, papain hydrolysis can prevent destruction by Ca(OH)₂ in the bone structure and effectively reduce the denaturation temperature of tilapia bone collagen. Moreover, papain hydrolysis can dramatically reduce the time required for liming (0.8% of traditional liming process spent). Papain hydrolysis is a clean production method that can replace traditional liming.     

Effects of Pretreatment on Properties of Gelatin from Perch (Lates Niloticus) Skin

Fish gelatins obtained from perch fish skin pretreated with various solutions containing acetic acid, sodium hydroxide (NaOH) and sodium chloride (NaCl) were successfully characterized for their nanostructure pattern using field emission scanning electron microscopy. Each pretreatment transformed collagen to gelatin with fibril, zigzag cracks, straight rods, and cross-linked rods nanostructure patterns. Pretreatment solutions also affect the gel yield, gel strength, amino acid profile, and functional groups in perch gelatin as analyzed by Fourier transform infrared spectroscopy. Samples pretreated with NaCl, NaOH, and acetic acid solution showed the highest gel yield (22.84%) and gel strength (179.84 g). Fourier transform infrared spectra for perch gelatins also revealed weak C–N amide II and III bond stretches as well as weak C=O bond stretch.     

Rheological properties of channel catfish (Ictalurus punctaus) gelatine from fish skins preserved by different methods

Gelatins were extracted from channel catfish skins preserved by different methods using 50 mmol/l acetic acid. Molecular weight distribution, gel strength and viscoelastic properties of gelatin samples were studied. Compared to gelatins from fresh and frozen skins, gelatin from dried channel catfish skin exhibited higher gel strength. This can be explained by the large α-chains content of gelatin from the dried skins. The gelling point and melting point of dried channel catfish skin gelatin solution were similar to those of fresh skin gelatin solution, but distinctly different from those of frozen skin gelatin. After maturation at low temperature, melting points of gelatins increased. But the melting point of frozen skin gelatin was still the highest among the three gelatin samples studied.     

The characteristics of gelatin extracted from sturgeon (Acipenser baeri) skin using various pretreatments

The physicochemical characteristics of gelatin obtained by different pretreatments of sturgeon (Acipenser baeri) skin with alkaline and/or acidic solutions have been studied. Visual appearance, pH, gel strength, viscosity and amino acid profile of the gelatins were evaluated. Pretreatment with alkaline solutions of Ca(OH)₂ and/or acetic acid (HAC) provided gelatin with a favourable colour. Pretreatment with alkali removed noncollagenous proteins effectively, whilst acid induced some loss of collagenous proteins. Gel strength and viscosity of gelatin pretreated with HAC or alkali followed by HAC were as high as gelatin extracted in the presence of protease inhibitors. Amino acid composition had no significant effect on the gelatin characteristics. The total acid concentration for the highest gel strength was inversely proportional to ionisation strength, and the preferred pH for extracting gelatin with the optimum gel strength was approximately 5.0. The results showed that any available protons, regardless of the type or concentration of the acid, inhibit protease activity, which significantly affects the gelatin characteristics.     

毛纱上浆用丁二酸酐酰化明胶浆料的制备及其性能

针对明胶在室温凝胶且在毛纱上浆时存在浆膜韧性差的问题,采用丁二酸酐(C₄H₄O₃)对明胶进行酰化改性,合成了一种毛纱室温上浆用改性明胶蛋白(Gel-C₄H₄O₃)浆料。借助红外光谱仪、X射线衍射仪、扫描电子显微镜及差示扫描量热仪对Gel-C₄H₄O₃浆料结构及玻璃化转变温度进行测试表征,系统研究了酰化度与Gel-C₄H₄O₃浆液和浆膜性能的关系。结果表明:C₄H₄O₃可与明胶分子链上的氨基发生酰化反应;与采用丙烯酸、丙烯酰胺、丙烯酸酯类单体接枝改性明胶浆料相比,C₄H₄O₃酰化改性后的明胶浆料在室温时不凝胶;当酰化度为0.96时,Gel-C₄H₄O₃浆液对毛纱表现出优良的黏附性,Gel-C₄H₄O₃浆膜的断裂强度和韧性显著增加。此研究为毛纱室温上浆提供了性能优良的浆料制备方法。     

Properties of Alaska Pollock Skin Gelatin: A Comparison with Tilapia and Pork Skin Gelatins

ABSTRACT:  The objective of this work was to compare the physiochemical and rheological properties of Alaska pollock skin gelatin (AG) to those obtained for tilapia and pork skin gelatins. Results were also obtained for some mixed gels containing AG and pork skin gelatin, or AG and tilapia gelatin. AG contained about 7% hydroxyproline (Hyp), which was lower than that of tilapia (∼11%) or pork skin gelatin (∼13%). Most of the protein fractions in AG were α chain, β chain, and other oligomers. The gel strength of AG was 98 gram-force at 10 °C, and increased at a greater rate than other gelatins with decreasing temperature. The gel melting point of AG was the lowest with the oil-drop method, while the viscosity of AG was the highest of the samples studied. The rheological properties of gelatins were determined using small amplitude oscillatory shear testing. G' was nearly independent of frequency for most of the gelatin gels, but AG gels showed a slight dependence on G' and a minimum in G". G' was found to be a power law function of concentration for all gelatins used: G'= k × Cⁿ. In rheological measurements, AG also showed the lowest gel melting temperature and sharpest melting region. Increasing gelatin concentration resulted in a higher melting temperature and a broader melting region for all gelatin gels. For both the AG-pork and AG-tilapia mixed gels, the gel melting temperatures decreased and melting regions narrowed as the AG fraction was increased.     

Characteristics of gelatin from the skin of unicorn leatherjacket (Aluterus monoceros) as influenced by acid pretreatment and extraction time

Gelatins from the skin of unicorn leatherjacket (Aluterus monoceros) pretreated with different acids (0.2 M acetic acid or 0.2 M phosphoric acid) and extracted with distilled water at 45 °C for various times (4 and 8 h) were characterized. Yields of 5.23–9.18 or 6.12–11.54% (wet weight basis) were obtained for gelatins extracted from the skin pretreated with 0.2 M acetic acid or 0.2 M phosphoric acid, respectively. Extracted gelatins contained α₁ and α₂ chains as the predominant components and some degradation peptides. The absorption bands of gelatins in FTIR spectra were mainly situated in the amide band region (amide I, amide II and amide ???) and showed the significant loss of molecular order of triple helix. Gelatin samples had a relative solubility greater than 90% in the wide pH ranges (1–10). The gel strength of gelatin from skin pretreated with phosphoric acid (GPA) was higher than that of gelatin from skin pretreated with acetic acid (GAA). Both GPA and GAA had the lower gel strength than that of commercial bovine gelatin (P < 0.05). Net charge of GAA and GPA became zero at pHs of 6.64–7.15 and 6.78–7.26, respectively, as determined by zeta potential titration. Emulsifying and foaming properties of GAA and GPA increased with increasing concentrations (1–3%, w/v). Those properties were governed by pretreatments and extraction time. Thus gelatin can be successfully extracted from unicorn leatherjacket skin using the appropriate acid pretreatment and extraction time.