两种方法提取的鸡肺胶原蛋白性质及保湿性研究

本文以鸡肺为原材料,利用酸提和超声辅助酸提法提取胶原蛋白,并对其性质及保湿性进行研究。结果表明,所提取的鸡肺胶原蛋白经氨基酸分析显示组成基本相似,甘氨酸含量最高,分别占24.12%和23.93%,亚氨基酸含量仅次之,分别占19.74%和22.28%。酸提和超声辅助酸提胶原蛋白在229.0和224.9 nm处有胶原蛋白的特征紫外吸收峰。SDS-PAGE显示两种鸡肺胶原蛋白中均含有α₁链、α₂链、少量的β链和γ链,傅里叶变换红外光谱及X-射线衍射图谱共同表明两种方法提取的鸡肺胶原蛋白分子排列紧密,均保持了原有的三螺旋结构,说明在超声辅助酸提过程中胶原蛋白的结构保持完好,三螺旋结构未被破坏。酸提的胶原蛋白等电点为7,粒径分布在340 nm左右;超声辅助酸提的胶原蛋白等电点为6,粒径分布在295 nm左右,结合胶原蛋白的溶解性说明了超声辅助酸提可破坏胶原蛋白的氢键,改变蛋白质的颗粒大小和聚集形态。扫描电镜结果表明超声辅助酸提的胶原蛋白结构呈连续纤维状并多孔,且颗粒直径明显减小。在放置24 h时,超声辅助酸提胶原蛋白的吸水性和保水性分别为常规酸提胶原蛋白的1.25倍和1.17倍。综上所述,超声辅助酸提未破坏胶原蛋白特有的三螺旋结构,通过改变氢键和蛋白的颗粒大小使得胶原蛋白具有更好的溶解性和吸湿保湿性。     

真空冷冻与喷雾干燥对鸡蛋全蛋粉理化性质及超微结构的影响

本文以鲜蛋为原料,目的是比较两种干燥方式对全蛋粉的理化性质和功能性质的影响。采用的方法是使用喷雾干燥与真空冷冻干燥两种干燥方式制备全蛋粉并对干燥后得到的全蛋粉的理化性质和功能性质进行了对比研究,探讨了两种干燥方式对全蛋粉的水分含量,水分活度,颗粒分布情况,溶解度,起泡性,乳化性的影响。同时分析比较了两种干燥方式制备的全蛋粉的微观结构图。结果表明,两种干燥方式制成的全蛋粉水分含量和水分活度差异不显著(p0.05),冷冻干燥全蛋粉的溶解度为93.32%,喷雾干燥全蛋粉溶解度87.88%,真空冷冻干燥全蛋粉的乳化活性和起泡力的最大值分别为0.338,62.6%,喷雾干燥全蛋粉的乳化活性和起泡力的最大值为0.248,53.4%。数据表明真空冷冻干燥制成的全蛋粉功能性质优于冷冻干燥制成的全蛋粉。而两种干燥方式制成的全蛋粉的颗粒分布情况与微观结构表征也存在显著差异。     

Changes in the physical properties,solubility, and heat stability of milk protein concentrates prepared from partially acidified milk

A limiting factor in using milk protein concentrates (MPC) as a high-quality protein source for different food applications is their poor reconstitutability. Solubilization of colloidal calcium phosphate (CCP) from casein micelles during membrane filtration (e.g., through acidification) may affect the structural organization of these protein particles and consequently the rehydration and functional properties of the resulting MPC powder. The main objective of this study was to investigate the effects of acidification of milk by glucono-δ-lactone (GDL) before ultrafiltration (UF) on the composition, physical properties, solubility, and thermal stability (after reconstitution) of MPC powders. The MPC samples were manufactured in duplicate, either by UF (65% protein, MPC65) or by UF followed by diafiltration (80% protein, MPC80), using pasteurized skim milk, at either the native milk pH (~pH 6.6) or at pH 6.0 after addition of GDL, followed by spray drying. Samples of different treatments were reconstituted at 5% (wt/wt) protein to compare their solubility and thermal stability. Powders were tested in duplicate for basic composition, calcium content, reconstitutability, particle size, particle density, and microstructure. Acidification of milk did not have any significant effect on the proximate composition, particle size, particle density, or surface morphology of the MPC powders; however, the total calcium content of MPC80 decreased significantly with acidification (from 1.84 ± 0.03 to 1.59 ± 0.03 g/100 g of powder). Calcium-depleted MPC80 powders were also more soluble than the control powders. Diafiltered dispersions were significantly less heat stable (at 120°C) than UF samples when dissolved at 5% solids. The present work contributes to a better understanding of the differences in MPC commonly observed during processing.     

超微粉碎对马铃薯渣理化性质和微观结构的影响

超微粉碎处理淀粉生产副产物马铃薯渣,探究粉碎前后及不同粒径的马铃薯渣理化性质和微观结构变化。结果为：超微粉碎主要影响了马铃薯渣的膳食纤维含量及其组成,随着粒度的降低,呈现出总膳食纤维含量（55.60%降至40.93%）和不溶性膳食纤维含量（47.42%降至26.06%）下降,可溶性膳食纤维含量明显提高的趋势（8.18%~14.87%）。同时,超微粉碎和粒度的降低提高了马铃薯渣的持水力、溶解性、膨胀力和持油力。超微粉碎后的马铃薯渣微观结构呈颗粒大小更均匀,趋近球体,且粒径较小的马铃薯渣颗粒的均匀程度更好;表明超微粉碎导致的粒度和比表面的改变并未对马铃薯渣中的纤维素晶体结构和淀粉晶体产生特殊影响,也并未引入新的官能团或生新的化合物。     

Production of silver carp bone powder using superfine grinding technology: Suitable production parameters and its properties

Superfine grinding technology is a new type of food processing that is employed to produce powders with outstanding properties such as high solubility, dispersion, adsorption, chemical reactivity and fluidity. The objective of this work was to study the superfine grinding technology on the silver carp bone and to optimize the operational parameters. The optimum processing conditions of superfine grinding were: feeding pressure of 0.85 MPa, grinding pressure of 1.0 MPa, feeding rate of 0.0325 g/s, feeding particle size of 150-300 μm and one pass through the grinder. Silver carp bone powder with average particle size (D₅₀) of 7.65 μm was produced at these conditions. It was found that the smaller particle size of the powder, the higher its fluidity, solubility, solubility of protein, electric conductivity and water holding capacity of the powder were. So the quality of the products produced by the superfine grinding technology was said to be improved.     

多糖类型对泥鳅鱼皮胶原可食膜性能的影响

目的:开发性能优异的复合可食性膜,探究不同类型多糖对胶原可食膜性能的影响。方法:以泥鳅鱼皮胶原蛋白为基本原料,选取果胶(酸性多糖)、普鲁兰多糖(中性多糖)、壳聚糖(碱性多糖)分别与胶原蛋白复合成膜,对复合膜的基本性质、机械性能和阻隔性能进行测定分析。结果:与添加果胶相比,普鲁兰多糖对泥鳅鱼皮胶原可食膜的膜厚度、含水率、不透明度影响均较小。3种不同类型的多糖都可以不同程度地降低胶原可食膜的水溶解率,增大其溶胀率。在机械性能方面,壳聚糖和少量普鲁兰多糖的添加可以改善胶原可食膜的综合机械性能,果胶可以增加胶原可食膜的断裂伸长率,但却极大降低了其抗拉强度。在阻隔性能方面,添加适量的壳聚糖可以提高胶原可食膜的阻水、阻油性能,而果胶和普鲁兰多糖的添加仅能提高胶原可食膜的阻油性能。结论:果胶对胶原膜机械性能和阻隔性能的影响与普鲁兰多糖及壳聚糖不同甚至相反。     

挤压膨化处理对婴幼儿米粉理化和体外消化特性的影响

为探讨婴幼儿米粉基料干法制造过程中挤压膨化处理对米粉特性的影响规律,对不同品种大米经挤压膨化得到米粉的理化和消化特性差异进行比较分析,结果表明:在相同挤压膨化条件下,不同大米之间淀粉组成差异明显,导致膨化度、吸水指数和水溶性指数差异显著(P<0.05);处理后由淀粉体外消化特性得出:早籼米中抗性淀粉含量最高,接近15%;糯米快速消化淀粉含量最低,小于75%。蛋白质消化特性结果显示,糯米制品的胃蛋白酶消化率和蛋白质总消化率均低于其它3种米粉,这可能是因糯米中蛋白质的结构和组成不同所致。研究结果为挤压膨化技术在米粉生产中的应用及对不同品种大米米粉的性能影响提供理论依据。     

Emulsions stabilized by heat-treated collagen fibers

The emulsifying properties of collagen fiber were modified by heat treatment at temperatures ranging from 50 to 85 °C for 20 or 60 min. In addition to heat treatment, the influence of pH (3.5 and 9.2) and the emulsifying process (rotor-stator device and high-pressure homogenizer) were evaluated on oil-in-water emulsions stabilized by collagen fiber through visual analysis (stability), microstructure and rheological measurements. Emulsions homogenized using solely the rotor-stator device showed phase separation and a larger mean droplet size (d₃₂), except for the emulsion composed by non-heated collagen fiber. The alkaline emulsions showed lower kinetic stability, since collagen fibers have a lower net charge (zeta potential) at higher pH values, decreasing the electrostatic stability process. Heat treatment slightly decreased the protein charge and significantly reduced the insoluble protein content, suggesting a decrease in the emulsifying properties of the collagen fiber. The use of high-pressure homogenization (20-100 MPa) made it possible to produce acid emulsions with a reduced droplet size and distribution. At 20 MPa, the emulsions showed a higher d₃₂ value (between 3.17 and 1.18 μm), while at 60 and 100 MPa the emulsions presented lower d₃₂ values (between 0.74 and 0.94 μm) without any significant variation between the different heat-treated collagen fibers, but showing a noticeable decrease in emulsion viscosity and elasticity with increases in the homogenization pressure and heat treatment.     

Characterization of stipe and cap powders of mushroom (Lentinus edodes) prepared by different grinding methods

The effects of micronization methods, mechanical and jet millings, on the physico-chemical properties of mushroom (Lentinus edodes) powder were investigated in contrast to shear pulverization. The powders of dried mushroom cap and stipe were prepared to obtain six powders. Compared to shear pulverization, mechanical and jet millings effectively reduced particle size and brought about a narrow and uniform particle size distribution. With the same material, powders from mechanical and jet millings had higher values in soluble dietary fiber content, surface area, bulk density, water soluble index and nutrient substance solubility, but lower values in the angles of repose and slide, water holding and swelling capacities than shear pulverized powder. These indexes were tightly dependent on particle size with absolute coefficients beyond 0.8330. With the same grinding method, cap powders possessed higher values in water soluble index, swelling capacity, bulk density, protein and soluble dietary fiber than stipe powders.     

不同粒径金花茶茶花粉体物理特性

研究3 种不同粒径范围金花茶茶花粉体的流动性、溶解性、功能成分皂苷溶出量等物理特性,并结合激 光粒度分布仪和扫描电子显微镜进行直观分析。结果表明：普通粉（平均直径133.90 μm）、超微粉（平均直径 15.76 μm）、纳米粉（平均直径201.50 nm）的粒径依次减小,细胞破碎程度、不规则度依次增加,差异显著;随粒 径减小,粉体的流动性、松密度、润湿性、膨胀力先减小后增加,以普通粉最高;持水力普通粉最高,超微粉次之; 水溶性、皂苷溶出量呈现先增大后略微减小的趋势。说明不同粒径金花茶茶花粉体特性各不相同,综合比较下,超微 粉具有较高的溶解率、皂苷溶出量,更容易被人体吸收,生物利用度高,加工方便,具有较好的开发前景。     

酶解前后可可粉体系的变化

可可粉在饮料中很不稳定,用纤维素酶、淀粉酶和木聚糖酶对其作用后,其成分、微观结构和带电性质都发生了变化。酶解后可溶性成分增加,这主要来自于多糖的降解和多酚的释放;但是分子质量在30000u上下的物质的分布没有发生很大变化;可溶性的粗蛋白和游离氨基酸的变化不明显;淀粉、蛋白质和细胞壁材的含量减少;酶解后可可粉的粒径变小,但是出现了部分聚集;酶解后CWM中的果胶的暴露,使得可可粉的Zeta电位由-20.7mv下降到-28.08mv。     

喷雾冷冻干燥对鸡蛋清蛋白结构和特性的影响

为了探究喷雾冷冻干燥(Spray freeze drying,SFD)对鸡蛋清蛋白结构及功能特性的影响,将其与喷雾干燥(Spray drying,SD)蛋清粉进行对比,并通过质构仪、差示扫描量热(D S C)、傅里叶变换红外光谱(FT-IR)、扫描电镜(SEM)、低场核磁共振(LF-NMR)等对其结构及特性进行测定。结果表明:SFD粉的变性温度比SD粉低了15.7℃,表面巯基含量低42.40%;SFD粉的α-螺旋和β-折叠结构比例大,分子结构更有序,蛋白聚集程度小,从而使其乳化特性得到改善;SEM分析表明,SFD粉呈大孔隙颗粒网络结构,溶解度增大。两种蛋清粉溶解度随pH的升高均呈先下降后上升的趋势,SFD粉溶解性和乳化性明显高于SD粉(P<0.05),凝肢硬度和束缚水含量显著低于S D粉(P<0.05),保水性差,两者的起泡性无显著差异。综上所述:与SD粉蛋白相比,SFD粉蛋白在结构和部分功能特性方面发生了显著变化,尤其在溶解度和乳化特性方面更具优势。     

皱纹盘鲍(Haliotis discus hannai)不同部位肌肉的蛋白分布特性

为了更好地了解鲍鱼的原料学属性,分析测定了皱纹盘鲍腹足肌肉三部位(闭壳肌、过渡区和裙边)的营养成分、蛋白组成及分布,并用光学显微镜观察了三部位肌肉的组织结构。结果表明,三个部位中闭壳肌部分的水分含量最低,而粗蛋白与粗脂肪最高;三部位中盐溶性蛋白与非蛋白氮含量较高,水溶性蛋白含量最低,裙边的肌基质蛋白的含量约为过渡区的2倍,闭壳肌部分的3倍,胶原蛋白含量丰富;SDS-PAGE中闭壳肌与过渡区部分蛋白分布相似,蛋白组成比裙边部分丰富;光学显微镜图中肌原纤维与胶原纤维的分布与蛋白含量测定结果一致,且肌肉纤维的横截面与纵截面中肌纤维的形态有所差异。鲍鱼三部分肌肉性质存在差异,研究结果可为鲍鱼的进一步加工和开发提供理论参考和实践依据。     

Studies on physicochemical and functional properties of commercial sweet whey powders

The objective of this study was to characterize variation and interrelatedness among primary functional and compositional parameters of commercially available sweet whey powders. Samples representing different plants/processes and cheese types were assayed for foaming capacity, foam stability, pH, protein content, soluble protein, turbidity, color, particle size distribution, lipid, and moisture. Data were analyzed using principal component analysis. Foaming capacity and stability varied from 10 to 220% and 0.1 to 14 min, respectively. Protein content and solubility ranged from 8.5 to 17.6% and 3.7 to 14.1%, respectively. Lipid content of sweet whey powder varied from 0.03 to 2.00%. The two main functional properties, foaming and protein solubility, did not show significant correlation with each other. Foaming properties showed a positive correlation to particle size and L* or lightness value, and negative correlation to lipid content. Protein solubility showed positive correlation with protein content and negative correlation with turbidity of the sample. Foaming behavior, protein, and particle size attributes were the main variables responsible for grouping of samples. Sweet whey powders from the same dairy plants were grouped together. The direct or indirect significance of these relationships to processing is detailed in this study.     

Dietary fiber from coconut residue: effects of different treatments and particle size on the hydration properties

The present work is aimed at the production of dietary fiber from underutilized coconut residue left after the extraction of milk, by subjecting it to physical treatments such as water washing, hot water washing, boiling water washing and pressure cooking, as well as solvent extraction. The fat content was reduced from 62% to 45% and 41% by treatment with boiling water and pressure-cooking, respectively. Water-holding, water retention and swelling capacities increased with decreasing fat content. A marked increase was observed in hydration properties when the fat content decreased from 10 to 2%. The hydration properties were maximum for 550 m particle size coconut fiber. For the higher particle size (1,127 m), the oil was trapped inside the fiber matrix, resulting in decreased hydration properties, whereas for the lower particle size (390 m) the rupture of the fiber matrix was responsible for low hydration properties. An attempt was made to compare the hydration properties of coconut dietary fiber with other commercially available dietary fibers.     

Using shear force,sarcomere length,particle size,collagen content,and protein solubility metrics to predict consumer acceptance of aged beef tenderness

In this study, the relationship between sensory evaluation and several objective metrics of beef tenderness was tested. Objective metrics included shear force, sarcomere length, collagen content, myofibrillar, and sarcoplasmic protein solubility and particle size analysis. These results were compared to consumer panel scores of tenderness for the same aged beef striploin (longissimus lumborum muscle) samples. There was found to be a significant relationship between sarcomere length, shear force, and particle size with tenderness scores. Collagen content and protein solubilities were not associated to tenderness scores (p > 0.05). Sarcomere length contributions for explaining tenderness variation were overlapped by the contributions of shear force (collinearity). Independent models demonstrated that the lower 95% confidence interval of the fitted regression line exceeded 50% acceptance of tenderness when shear force values <42.6 N and when particle size values <198 μm. We can recommend these as thresholds for consumer acceptance of beef tenderness, although considerations of sample type, analytical methodology, and consumer demographics should be made prior to their adoption. This provision was based on the variation in tenderness scores evident between individual panelists and experimental striploins.     

Effect of processing methods and protein content of the concentrate on the properties of milk protein concentrate with 80% protein

In recent years, a large increase in the production of milk protein concentrates (MPC) has occurred. However, compared with other types of milk powders, few studies exist on the effect of key processing parameters on powder properties. In particular, it is important to understand if key processing parameters contribute to the poor solubility observed during storage of high-protein MPC powders. Ultrafiltration (UF) and diafiltration (DF) are processing steps needed to reduce the lactose content of concentrates in the preparation of MPC with a protein content of 80% (MPC80). Evaporation is sometimes used to increase the TS content of concentrates before spray drying, and some indications exist that inclusion of this processing step may affect protein properties. In this study, MPC80 powders were manufactured by 2 types of concentration methods: membrane filtration with and without the inclusion of an evaporation step. Different concentration methods could affect the mineral content of MPC powders, as soluble salts can permeate the UF membrane, whereas no mineral loss occurs during evaporation, although a shift in calcium equilibrium toward insoluble forms may occur at high protein concentration levels. It is more desirable from an energy efficiency perspective to use higher total solids in concentrates before drying, but concerns exist about whether a higher protein content would negatively affect powder functionality. Thus, MPC80 powders were also manufactured from concentrates that had 3 different final protein concentrations (19, 21, and 23%; made from 1 UF retentate using batch recirculation evaporation, a similar concentration method). After manufacture, powders were stored for 6 mo at 30°C to help understand changes in MPC80 properties that might occur during shelf-life. Solubility and foaming properties were determined at various time points during high-temperature powder storage. Inclusion of an evaporation step, as a concentration method, resulted in MPC80 that had higher ash, total calcium, and bound calcium (of rehydrated powder) contents compared to concentration with only membrane filtration. Concentration method did not significantly affect the bulk (tapped) density, solubility, or foaming properties of the MPC powders. Powder produced from concentrate with 23% protein content exhibited a higher bulk density and powder particle size than powder produced from concentrate that had 19% protein. The solubility of MPC80 powder was not influenced by the protein content of the concentrate. The solubility of all powders significantly decreased during storage at 30°C. Higher protein concentrations in concentrates resulted in rehydrated powders that had higher viscosities (even when tested at a constant protein concentration). The protein content of the concentrate did not significantly affect foaming properties. Significant changes in the mineral content are used commercially to improve MPC80 solubility. However, although the concentration method did produce a small change in the total calcium content of experimental MPC80 samples, this modification was not sufficiently large enough (<7%) to influence powder solubility.     

蛋白组分对米蛋白功能性质影响的研究

以不同配比米蛋白组分的样品为试材,比较各样品的功能性质变化,明确各蛋白组分对蛋白产品品质影响的差异,为今后进行分子设计和重组生产米蛋白产品提供理论支撑。通过各蛋白样品的溶解性,乳化特性,起泡特性,持水性/持油性等功能性质研究,结果表明,米糠浓缩蛋白的溶解性比大米浓缩蛋白高200%左右;米糠蛋白各功能性质显著优于大米蛋白,但大米蛋白的起泡稳定性比米糠蛋白提高近20%。米蛋白中的清蛋白提高产品的溶解性、持水性/持油性,降低起泡稳定性;醇溶蛋白提高产品的乳化特性;谷蛋白提高产品的起泡稳定性。蛋白产品的功能性质与蛋白组分的组成密切相关。     

鱼皮胶原纤维-淀粉复合膜的制备及性能研究

为明确鱼皮胶原纤维尺寸及其添加量对鱼皮胶原纤维-淀粉复合膜性能的影响,本研究利用醋酸预处理鱼皮(3、6、9、12 h)获得了不同尺寸的胶原纤维(CF3、CF6、CF9、CF12),考察了不同类型胶原纤维及其添加量对共混膜性能的影响。采用傅里叶红外光谱技术、差示扫描量热法及扫描电子显微镜对复合膜进行结构表征。结果表明:添加鱼皮胶原纤维后,复合膜的断裂伸长率和水蒸气透过系数均增加,溶解性降低;当CF3和CF6添加量分别为7.5%和10%时能增强复合膜的抗拉强度,而且以10% CF6制备的复合膜抗拉强度性能最好,添加CF9和CF12时,复合膜的抗拉强度呈降低现象。对添加10% CF6制备的复合膜和纯淀粉膜进行表征,发现胶原纤维与淀粉相容性良好,在成膜过程中,胶原纤维交错在淀粉膜中,两者之间形成了氢键,但复合膜的热稳定性下降。     

中低温水溶季铵阳离子淀粉浆料的合成及其浆纱性能

为了解决淀粉中低温水不溶的问题,根据中低温浆纱工艺对浆料水溶性、黏度、成膜性及对纺织纤维粘附性能的要求,采用酸解、季铵阳离子化和乙醇-碱法对淀粉进行改性,合成了一种中低温水可溶季铵阳离子淀粉浆料。采用扫描电了显微镜、红外光谱、电泳仪分析了所制得浆料的微观结构。研究了乙醇-碱法制备中低温水可溶淀粉时,反应温度、反应时间、乙醇用量、水含量、碱量对该淀粉浆料溶解性能的影响,测试了该淀粉浆料的浆液、浆膜性能。结果表明,反应温度为60℃,反应时间为50min,淀粉、水、乙醇和碱的量比为1：20：8：0.4时,所制得的淀粉浆料可溶于室温水中,浆液具有良好的黏度和抗凝沉性。