干燥方式对蛋清蛋白理化性质和功能特性的影响

为探究干燥方式对蛋清蛋白（egg white protein,EWP）功能特性的影响及其内在机理,分别通过喷雾干燥与真空冷冻干燥制备蛋清蛋白粉,并对其蛋白结构、理化性质与功能特性进行研究。结果表明,与蛋清液（EWP-C）相比,喷雾干燥使蛋清蛋白（EWP-P）的内源性荧光强度降低,表面疏水性和表面游离巯基含量增大。傅里叶变换红外光谱分析显示,EWP-P的α-螺旋、β-折叠和β-转角分别为16.30%、25.72%和40.23%,冷冻干燥蛋清蛋白（EWP-D）分别为20.43%、24.32%和35.69%。不同pH下,EWP-D的溶解度均高于EWP-P,表面张力小于EWP-P。此外,EWP-P的接触角为99.62°,高于EWP-D（接触角为65.97°）,表明喷雾干燥能显著提高蛋白的疏水性（P<0.05）。EWP-D在不同pH下的乳化性、乳化稳定性以及起泡性均大于EWP-P,但起泡稳定性更小,这与EWP-D较高的溶解性与较低的表明疏水性有关。荧光倒置显微镜及激光共聚焦扫描显微镜分析表明EWP-D乳液的微粒更小,分布更均匀,其稳定性高于EWP-P。综上,喷雾干燥蛋清蛋白的β-折叠结构较多,表面游离巯基含量和表面疏水性较高,具有较好的凝胶性;冷冻干燥蛋清蛋白的表面疏水性较小,且表面张力小、溶解度大,具有更好的乳化能力与起泡性。     

三聚磷酸钠对猪肉肌原纤维蛋白功能特性的影响

以猪肉肌原纤维蛋白（myofibril protein,MP）为研究对象,探讨不同质量浓度三聚磷酸钠（sodium tripolyphosphate,STP）的添加对MP乳化性、乳化稳定性、起泡性等7 个功能特性指标的影响,并进行相关性分析。结果表明：随着STP质量浓度升高,MP的乳化性、乳化稳定性、起泡性、起泡稳定性、凝胶强度和凝胶保水性均呈上升趋势,表面疏水性呈下降趋势;MP的起泡性和凝胶强度在STP质量浓度为0.3 g/100 mL时最大,乳化性、表面疏水性和凝胶保水性在STP质量浓度为0.4 g/100 mL时效果最佳;MP的起泡性、起泡稳定性和乳化性呈极显著正相关（P＜0.01）,乳化性与乳化稳定性呈显著正相关（P＜0.05）,乳化性、乳化稳定性、起泡性、起泡稳定性与表面疏水性呈极显著负相关（P＜0.01）,与凝胶保水性呈极显著正相关（P＜0.01）,表面疏水性与凝胶保水性呈极显著负相关（P＜0.01）,表面疏水性与凝胶强度呈极显著正相关（P＜0.01）。STP可以增强MP的功能特性,其质量浓度为0.3～0.4 g/100 mL时效果最佳。改善乳化性、起泡性和表面疏水性等界面性质可以增强MP的凝胶特性。     

不同NaCl浓度条件下亚麻籽胶对肌原纤维蛋白凝胶作用力及乳化特性的影响

为改善低盐肉制品凝胶乳化品质的降低,明确亚麻籽胶（flaxseed gum,FG）添加对肉制品品质的影响,以肌原纤维蛋白（myofibrillar protein,MP）为研究对象,通过测定乳析指数、电位值、粒径、显微观察研究不同NaCl浓度条件下FG对MP乳液乳化稳定性的影响,而化学键的测定显示FG对MP凝胶化学作用力的影响。结果表明,形成MP凝胶及FG-MP凝胶体系的关键是二硫键和非二硫共价键的贡献;不同NaCl浓度对FG-MP乳液的乳析指数、ζ-电位、粒径的影响均不显著（P＞0.05）,而MP乳液随着NaCl浓度的提高,乳化稳定性、ζ-电位、粒径均显著变化（P＜0.05）。特别是在低浓度NaCl条件下,FG的加入可以显著提高MP乳液的稳定性（P＜0.05）。显微观察发现加入FG可以改善MP乳液液滴聚集的现象。因此,说明在低浓度NaCl条件下加入FG可以显著提高肌原纤维蛋白乳液的乳化稳定性,提高其抗盐能力,促进亚麻籽在肉制品中的应用。     

火麻油复合纳米乳液的制备及稳定性研究

以火麻油、大豆分离蛋白、卵磷脂以及山柰酚为原料制备火麻油复合纳米乳液。研究在不同超声功率（100、200、300、400 W）下处理10 min对乳液稳定性的影响,揭示复合体系稳定性随超声条件变化的规律。通过粒径、Zeta电位、内源荧光光谱以及表面疏水性的测定可知,当超声功率为300 W时,由于超声处理的空化作用使体系分散均匀,蛋白质内部的疏水性残基暴露于表面,乳液的内源荧光光谱红移,荧光强度与表面疏水性均提高。通过测定样品的乳化性、乳析指数以及氧化稳定性可知,当超声功率为300 W时,乳液有较好的物理稳定性和氧化稳定性。这表明适当的超声处理有利于提升复合体系稳定性。研究结果对延长火麻油货架期有参考作用,对构建复合乳液体系有借鉴意义。     

疏水淀粉皮克林乳液凝胶的稳定机理及影响因素

研究不同因素（温度、pH值和离子强度）对淀粉-脂质复合物（starch-fatty acid complex,SFAC）稳定的皮克林乳液凝胶的影响规律并揭示其稳定机理。激光共聚焦扫描显微镜和扫描电子显微镜结果显示,SFAC颗粒通过吸附于油水界面,形成一层紧密的屏障包裹油滴,形成呈圆状的乳滴,乳滴之间紧密堆积形成稳定的乳液凝胶网络结构。光学显微镜、粒径分布及Zeta电位等结果显示该疏水淀粉皮克林乳液凝胶在pH 3～9范围内以及离子浓度0.1～0.9 mol/L条件下都能维持乳液凝胶结构并具有良好的贮藏稳定性。此外,该皮克林乳液凝胶具有热可逆性,在高温下粒径增大、黏度下降,出现流动性,冷却后可重新呈现凝胶状。研究结果表明疏水淀粉皮克林乳液凝胶在较宽的温度、pH值和离子强度范围内均有较高稳定性,适用于多种植物油的稳定。     

热处理温度对猪肝水溶性蛋白乳化性质的影响

以新鲜猪肝为原料,研究不同温度处理对猪肝水溶性蛋白乳化性质的影响。以猪肝水溶性蛋白为研究对象,经过25、40、50、60、70、80℃加热处理,与大豆油形成乳化体系后,测定乳化活性和稳定性、乳析指数、界面蛋白浓度等来研究乳化性质的变化。结果表明,热处理温度对猪肝水溶性蛋白的乳化性、表面疏水性与乳化液的乳析指数、界面蛋白含量和种类、液滴粒径大小及其分布、显微结构均有显著性影响。综合各项指标变化趋势可知,加热温度为60℃时,猪肝水溶性蛋白的乳化活性值和乳化稳定性值均最大,分别为40.42 m~2/g和52.36%,为猪肝蛋白在乳化食品中的应用提供了可靠的理论依据。     

超声处理大豆分离蛋白与壳聚糖复合物对O/W型乳液稳定性的影响

为探究超声处理大豆分离蛋白-壳聚糖（soybean protein isolate-chitosan,SPI-CS）复合物对形成O/W型乳 液性质的影响,主要研究了复合物表面疏水性、乳化活性、乳化稳定性与油-水界面张力、乳液粒径、乳液稳定性 之间的关系。结果表明：未经超声处理的SPI-CS复合物表面疏水性、乳化活性、乳化稳定性和界面吸附性较低,形 成的O/W型乳液粒径相对较大,约100 μm,乳液Zeta电位较低,乳滴有发生聚集的倾向。乳液贮存7 d后乳层析指数 最高。经超声处理后SPI-CS复合物形成的乳状液性质发生明显变化,随着超声功率的增加,形成的O/W型乳液的稳 定性有所增加：超声功率为400 W时SPI-CS复合物形成的乳液最为稳定,乳层析指数最低;当超声功率超过400 W 时,乳液的光学显微镜观察显示其粒径有所增大,同时乳液的Zeta电位、乳化活性和乳化稳定性明显下降,界面张 力降低缓慢。超声处理暴露了蛋白质分子的内部结构,使部分结构展开、柔性增加,促进了其与壳聚糖之间的静电 相互作用,说明超声处理的大豆分离蛋白与壳聚糖形成的复合物影响了O/W型乳液的稳定性及相关性质。     

热处理对于鸡蛋全蛋液功能性质的影响

研究了不同强度的热处理条件（处理温度61、64、67℃,处理时间2.5、3.5、4.5min）对于鸡蛋全蛋液蛋白质的溶解性、乳化性、起泡性、表面疏水性和表面巯基含量的影响。结果表明：随着加热温度的升高和处理时间的延长,全蛋液蛋白质溶解度与泡沫稳定性不同程度的下降,而表面疏水性、表面游离巯基含量、乳化稳定性则不同程度的提高。当温度高于61℃时,全蛋液起泡性随温度升高和时间的延长而降低,同时,研究还发现热处理对于全蛋液乳化活力的影响不明显。     

纳米SiO2改性4 种大分子材料的乳液制备及性质

为提高乳液稳定性,采用纳米SiO2改性明胶（gelatin,GE）、大豆分离蛋白、壳聚糖和阿拉伯胶（gum arabic,GA）制备茶油乳液。以乳化活性、乳化稳定性、离心稳定性、平均粒径、流变特性为考察指标,探究质量分数3.000%的纳米SiO2对4 种大分子材料复合乳液性质的影响,并对乳液的微观结构及油滴分布进行观察。结果表明,纳米SiO2能增强乳液稳定性,其中GE-纳米SiO2复合乳液综合性质最佳。添加纳米SiO2后乳化活性和乳化稳定性显著增加（P＜0.05）,离心稳定性降低68.444%。平均粒径为8.472 μm,乳液粒径最小且分布均匀,表面光滑呈球状。流变表现为典型的弱凝胶特性,稳定性良好。研究结果可为天然高分子和纳米SiO2乳液的制备和应用提供实践基础。     

鱼鳞明胶与哺乳动物明胶性质的比较

研究了酶法制备的草鱼鱼鳞明胶的理化性质,并将其与哺乳动物明胶的性质作了比较。研究发现,草鱼鱼鳞明胶中富含甘氨酸、脯氨酸、羟脯氨酸和丙氨酸,而亚氨基酸、总疏水性氨基酸的含量以及平均疏水性值要小于哺乳动物明胶;分子质量分布主要以α组分和β组分为主,占明胶分子总量的88%;胶凝温度和熔化温度分别为20.8℃和26.9℃,低于哺乳动物明胶;特性黏度约为0.73;表面疏水性指数为259.59,有较好的乳化性和起泡性。此外发现,明胶的高凝胶强度和胶凝速度主要取决于明胶(α+β)组分的含量,而明胶胶凝和熔化温度则主要取决于亚氨基酸的含量,不同来源明胶的特性黏度η仅与其α组分(α1+α2)的含量存在线性相关。     

Effect of microwave extraction temperature on the chemical structure and oil-water interface properties of fish skin gelatin

This study investigated the effect of microwave extraction temperature on the chemical structure and oil-water interface properties of fish skin gelatin. Results showed that increasing microwave extraction temperature from 55 to 75 °C led to the degradation of α subunits and breaking of the triple helical structure of gelatin, consequently exposing more hydrophobic groups and showing an improvement of amphiphilicity (58.35°-81.65°). Correspondingly, the interface pressure and adsorption also respectively increased from 8.00 to 8.90 mN/m and 43.70% to 93.66% due to its enhanced amphiphilicity. Furthermore, the volume-mean diameter and creaming index (CI) of emulsion obviously decreased, but the water holding capacity significantly increased, implying an improvement of emulsifying property. The rheological results showed the emulsion displayed a typical shear thinning behavior, and the apparent viscosity increased from 230 to 1339.4 Pa·s with the increase of microwave extraction temperature (55–75 °C) and concentration (1.0–3.0 wt%) at 0.1 s⁻¹. The possible reason is that more gelatin molecules participated in the formation of dense network structure of continuous phase due to the higher amphiphilicity. This work would provide guiding significance for green extraction of fish skin gelatin and its application in stabilizing emulsion.     

基于鱼鳞贮藏方式改善鳙鱼鱼鳞明胶的功能特性

鱼鳞的贮藏方式会影响鱼鳞明胶的品质,本实验研究了太阳晒干后室温贮藏、4 ℃贮藏、－20 ℃贮藏和 60 ℃热风干燥后室温贮藏对鳙鱼鱼鳞明胶凝胶强度、乳化活性和起泡能力的影响,并通过傅里叶变换红外光谱、 十二烷基硫酸钠-聚丙烯酰胺凝胶电泳和扫描电子显微镜表征经不同方式贮藏后制备得到的鱼鳞明胶的结构特性。 结果表明：4 种贮藏方式不会破坏明胶的分子质量分布（α链、β链和高分子聚合物）和傅里叶变换红外光谱的特征 性吸收峰（酰胺A带、酰胺I带、酰胺II带和酰胺III带）。4 种贮藏方式都能提升鱼鳞明胶的乳化活性和起泡能力, 其中,－20 ℃贮藏鱼鳞1 个月改善明胶乳化活性和起泡能力的效果最佳。除60 ℃热风干燥之外,其他贮藏方式均 能改善鱼鳞明胶的凝胶强度,这可能与其相应的结构特征变化有关。相比新鲜鱼鳞和60 ℃热风干燥鱼鳞,太阳晒 干和低温方式（4 ℃和－20 ℃）贮藏鱼鳞使得鱼鳞明胶α链、β链和高分子聚合物含量增加,酰胺A带吸收峰的波数 降低,鱼鳞明胶网络结构的致密性增加。     

以明胶为主要壁材的β-胡萝卜素微胶囊化

以明胶与蔗糖作为复合壁材对β－胡萝卜素的微胶囊化工艺进行了探讨，结果表明，明胶选用Ｇ２００为宜，壁材中明胶与蔗糖比例３∶１７（体系壁材固形物浓度２０％，黄原胶０．３％），微胶囊化工艺参数：乳化均质压力４０Ｍｐａ（乳化温度７０℃），喷雾干燥进风温度１９５℃（出风温度８０～９０℃）。     

均质压力及喷雾干燥温度对鱼油微胶囊化的影响

采用辛烯基琥珀酸酯淀粉Hi-Cap100和葡萄糖浆作为鱼油微胶囊的壁材。研究了不同均质压力下乳化液黏度、粒径和粒径分布规律,考察了不同均质压力下乳化液特性与鱼油微胶囊包埋率、表面油含量之间的相关性,探讨了喷雾干燥温度对包埋率和鱼油过氧化值(POV)的影响。研究结果表明,随着均质压力的增加,乳化液黏度和平均粒径逐渐减小,而粒径分布离散度总体呈下降趋势,在40MPa时最小,说明此时粒径分布均一性最佳;喷雾干燥温度增加时,鱼油包埋率先增后减,POV值先减后增,在进/出口温度为140℃/70℃时有最高的包埋率和最低的POV值。通过分析确定最佳工艺参数如下,均质压力为40MPa,喷雾干燥进口温度为140℃,出口温度为70℃。在上述最适工艺条件下,鱼油微胶囊平均粒径为5.97μm,表面油含量为2.03%,微胶囊化包埋率为95.6%,在扫描电镜下观察微胶囊表面和内部结构良好,具有良好的包埋效果。     

不同干燥方式对明胶特性的影响

系统研究了不同干燥方式(热风干燥,真空冷冻干燥和喷雾干燥)对明胶性质的影响,包括得率、色差、十二烷基硫酸钠-聚丙烯酰胺凝胶电泳(sodium dodecyl sulfate-polyacrylamide gel electrophoresis,SDS-PAGE)、凝胶强度、凝胶持水力、疏水性以及傅里叶变换红外光谱(Fourier transform infrared spectroscopy,FTIR)。结果表明,由于贴壁行为和涡旋分离损失的影响,使得喷雾干燥明胶的得率明显较低(P<0.05)。喷雾干燥和真空冷冻干燥可减轻不良色泽的产生,并且降低干燥过程中明胶的氧化和降解,保留更多的高分子亚基,进而增加了明胶的凝胶强度和凝胶持水力。此外,喷雾干燥的明胶由于疏水基团的暴露以及较多的亚基组分可能含有更多的疏水基团,显示出最高的疏水性(P<0.05),冷冻干燥的明胶次之,热风干燥的明胶最低。红外结果表明,热风干燥和真空冷冻干燥破坏了明胶的构象,而喷雾干燥更有利于明胶在凝胶过程中,形成类三螺旋结构。该文可为绿色明胶的干燥方法和工业化应用提供理论依据和指导意义。     

Emulsifying Property and Antioxidative Activity of Cuttlefish Skin Gelatin Modified with Oxidized Linoleic Acid and Oxidized Tannic Acid

Cuttlefish skin gelatins modified with oxidized linoleic acid (OLA) and oxidized tannic acid (OTA) were characterized and determined for emulsifying properties and antioxidative activity. Modification of gelatin with 5% OTA increased the total phenolic content and 1,1-diphenyl-2-picrylhydrazyl, 2,2′-azinobis(3-ethylbenzothiazoline-6-sulphonic acid) radical scavenging activity and ferric reducing antioxidant power of gelatin–OTA. Incorporation of OLA into gelatin (OLA-to-free amino group molar ratio of 10:1) increased surface hydrophobicity of gelatin from 17.39 to 32.38 and reduce surface tension at air/water interface of gelatin solution from 53 to 32 mN/m. Gelatin–OLA had the increase in emulsion activity index, compared with gelatin without modification and was capable of producing a fine emulsion (d ₃₂?=?0.79 μm, d ₄₃?=?0.82 μm). Modification of gelatin–OLA complex with OTA at different concentrations (2.5%, 5%, and 10%) increased antioxidative activity but decrease emulsifying properties. However, gelatin–OLA modified with 5% OTA had higher emulsifying properties than the commercial gelatin (bovine gelatin). The presence of an alkyl group and a hydroxyl group in gelatin after modification with OLA and OTA, respectively, was revealed by Fourier transform infrared study. Coincidental decrease in free amino group was also noticeable in modified gelatin. Menhaden oil-in-water emulsion stabilized by gelatin modified with OLA and 5% OTA was more resistant to lipid oxidation and phase separation as evidenced by the lower thiobarbituric acid reactive substances value and smaller oil droplet size, compared with that stabilized by commercial bovine gelatin. Thus, the modification of gelatin by both OLA and OTA was able to improve antioxidative and emulsifying properties of cuttlefish skin gelatin.     

天然和热处理大豆蛋白稳定乳液的性质研究

热处理(901、20℃)修饰的大豆分离蛋白用于制备水包油(O/W)乳液,并对天然和热处理蛋白乳液的粒径、微结构、絮凝率和分层稳定性进行表征。热处理蛋白的水力学半径随蛋白浓度和加热温度的增加而增加,证实了可溶性聚集体的产生。乳液粒径和分层稳定性受离子强度、聚集体粒径影响。低离子强度下(0 mmol/L),与天然蛋白相比,热处理蛋白乳液粒径较大,20 d放置后未发生分层。离子强度的增加(100mmol/L)导致天然蛋白乳液粒径明显增大;而热处理蛋白乳液则表现出较高耐盐性,体现在更小的粒径、絮凝率和分层指数。与90℃热处理相比1,20℃热处理减小了乳液液滴的粒径和絮凝。     

Changes in functional properties of shark (Isurus oxyrinchus) cartilage gelatin produced by different drying methods

Fish gelatins extracted from shark ( Isurus oxyrinchus ) cartilage were dried by three different methods: freeze drying, hot-air drying and spray drying; and their functional properties were investigated. Freeze-dried gelatin was found to have the strongest gel strength, while gelatins made at high temperatures formed weaker gels. The 135-kPa gel strength of freeze-dried gelatin was relatively high. While foam formation ability of the freeze-dried gelatin was the highest, its foam stability was the lowest. In addition, spray-dried gelatin had the best emulsion capacities. Dynamic viscoelastic properties of shark cartilage gelatins prepared by these drying methods were closely correlated with their gel strength. Elasticity modulus ( G '; Pa) and loss modulus ( G "; Pa) of the freeze-dried gelatin had higher values than those prepared by hot-air drying and spray drying; viscoelastic properties of the freeze-dried gelatin were maintained longer than those of other drying methods.     

Antioxidative activity and emulsifying properties of cuttlefish skin gelatin modified by oxidised phenolic compounds

Antioxidative activity and emulsifying properties of cuttlefish skin gelatin modified by different oxidised phenolic compounds including caffeic acid, ferulic acid and tannic acid at different concentrations were investigated. Oxidised phenolic compounds were covalently attached to gelatin as indicated by the decrease in amino groups. Fourier transform infrared spectroscopic studies indicated the presence of an aromatic ring and a hydroxyl group in gelatin after modification. Modified gelatin had the increased antioxidative activity but the decreased surface hydrophobicity. Gelatin modified with 5% oxidised tannic acid had no change in emulsifying properties. Emulsion stability and oxidative stability of menhaden oil-in-water emulsion stabilised by 0.5% and 1.0% gelatin without and with modification by 5% oxidised tannic acid were studied. Both gelatins at a higher concentration (1.0%) yielded an emulsion with a smaller particle size. Modified gelatin inhibited the formation of TBARS in the emulsion more effectively than the control gelatin throughout the 12 days of storage.