利用聚丙烯酰胺凝胶电泳技术分析蜂蜜蛋白质行为

拟采用蛋白质电泳技术对蜂蜜的电泳行为进行分析,以探索蜂蜜蛋白质行为,为蜂蜜真伪鉴别开辟一条新途径,测定不同品种、不同产地的蜂蜜与掺假蜂蜜蛋白质含量以及SDS-PAGE电泳行为。结果表明：不同品种、不同产地的蜂蜜其蛋白质含量与电泳行为有明显的差异;掺假蜂蜜蛋白质含量明显低于真蜂蜜,但二者的SDS-PAGE谱图差别不大。     

河蚬中水溶性蛋白的提取及其抗氧化性质

研究超声波辅助法提取河蚬水溶性蛋白的工艺。以水溶蛋白的提取率为考察指标,以料液比、提取时间、提取温度和超声功率为考察因素,采用响应面法对河蚬水溶性蛋白提取工艺条件进行优化设计,并对其进行抗氧化研究。结果表明：最佳河蚬水溶性蛋白提取工艺条件为料液比1∶20、提取时间23 min、提取温度48 ℃、超声功率920 W,此条件下河蚬水溶性蛋白提取率达到最大值,为67.70%。其中,提取时间和超声功率对河蚬水溶蛋白提取率的影响显著。超声波的空化和振动作用可以促进细胞的破碎,使目标产物与溶剂充分混合,增大提取率,缩短提取时间,对河蚬中水溶性蛋白的提取具有很大意义。河蚬提取液具有较强的清除1,1-二苯基-2-三硝基苯肼自由基、超氧阴离子自由基的能力和较强的铁离子还原能力,而清除羟自由基的能力较弱。     

糖基化反应改善鱼肉肌原纤维蛋白功能特性及其机制研究进展

糖基化反应是一种有效改善蛋白质功能特性的方法。文中结合国内外有关鱼肉肌原纤维蛋白糖基化改性的最新研究进展,综述了糖基化改性对于鱼肉肌原纤维蛋白功能特性的影响,探讨了鱼肉肌原纤维蛋白—多糖复合物的形成及其功能特性变化的机理。     

Innovations in value-addition of edible meat by-products

While muscle foods are the more commonly consumed portion of an animal, meat by-products such as the entrails and internal organs are also widely consumed. Considered high-priced delicacies or waste material to be tossed away, the use and value of offal-edible and inedible meat by-products depend entirely on the culture and country in question. The skin, blood, bones, meat trimmings, fatty tissues, horns, hoofs, feet, skull, and internal organs of harvested animals comprise a wide variety of products including human or pet food or processed materials in animal feed, fertilizer, or fuel. Industry is using science and innovation to add value to animal by-products far beyond its usual profitability. Regardless of the final product's destination, it is still necessary to employ the most up-to-date and effective tools to analyze these products for nutritional properties, to search for key active molecules in nutrition like bioactive peptides, food safety (antimicrobial peptides), medicine, cosmetics or other fields, to develop new technological applications and to continue innovation towards advanced value-addition of meat by-products.     

葵花籽油酶法提取的研究

采用水酶法从葵花籽中提取葵花籽油。通过对比试验确定最佳用酶,利用单因素和正交试验探讨原料烘烤时间、酶用量、酶解时间以及料液比对提油效果的影响,并通过验证试验对正交试验结果进行了验证。结果表明:中性蛋白酶试验效果最好;水酶法提取葵花籽油的最佳工艺参数为:烘烤时间16h,酶用量1%,酶解时间4h,料液比1:5(w/v)。验证试验结果表明葵花籽游离油得率80.94%,过氧化值4.57mmol/kg,渣中蛋白含量3.36%。     

饮料浑浊活性蛋白研究进展

浑浊活性蛋白易与多酚发生相互作用,并引起饮料浑浊和沉淀。文章对饮料浑浊活性蛋白的性质、分离以及检测方法进行了综述,同时还对饮料浑浊活性蛋白的控制技术进行了分析,并对今后的研究重点进行了展望。     

Rehydration process of milk protein concentrate powder monitored by static light scattering

Static light scattering (SLS) was applied to monitor the rehydration process of milk protein concentrate (MPC) powder. The size distribution and volume concentration of the suspended powder particles were measured to quantify the dissolution kinetics of MPC powder. The results obtained showed that the low solubility index reported for MPC85 (85% protein) powder at room temperature was the consequence of slow dissolution kinetics rather than the presence of a large amount of insoluble material in the rehydrated powder. The rehydration process of MPC85 powder occurs in two overlapping steps: the disruption of agglomerated particles into primary powder particles and, simultaneously, the release of material from the powder particles into the surrounding aqueous phase. The latter process appeared to be the rate-limiting step of dissolution of MPC85 and was accelerated by an increase of the solvent temperature.     

Isostrength Comparison of Large-Strain (Fracture) Rheological Properties of Egg White and Whey Protein Gels

The effects of protein concentration and heating conditions on the physical properties of whey protein isolate (WPI) (in 50 mM NaCl, pH 7) and egg white (pH 9) gels were examined. Egg white and WPI gels had similar values for shear stress at fracture (i.e., isostrength), while trends for shear strain at fracture were protein-type specific. The rigidity ratio (R_0.3), ratio of the rigidity at fracture (G_f) to the rigidity at 30% of fracture strain, measured departure from the stress-strain relationship of an ideal Hookean solid. All gels fit master curves of G_f vs R_0.3, which were described by a power law model of R_0.3=A(G_f)-°19, where "A" showed protein type-specific characteristics.     

Structure of soya glycinin and conglycinin gels

Gels of glycinin and conglycinin formed at various heating temperatures, in the absence and presence of 0.2M sodium chloride were characterised by transmission electron microscopy. In distilled water both proteins formed gels consisting of strands with a thickness of 10–15 nm. The strands of glycinin were very regular and cross sections of strands showed a hollow cylindrical structure. In the presence of sodium chloride, glycinin formed an aggregated gel structure at 85°C, but at 95°C an ordered strand structure was formed. Dissociation of the quaternary structure on heating and reassociation of subunits into regular strands were considered the most probable mechanisms for strand formation from glycinin. The aggregated structure at 85°C was interpreted as a transient state prior to dissociation. Conglycinin rich gels were less regular and more crosslinked than gels of glycinin. Also, the strands of conglycinin showed a complex mode of aggregation possibly in the form of double spirals. The addition of sodium chloride caused a denser and more aggregated structure at 75 and 85°C, but the effects were not as drastic as in the case of glycinin. Heating temperature had only minor effects on the gel structure in the range studied.     

Effect of ionic strength and temperature on interaction between fish myoglobin and myofibrillar proteins

ABSTRACT:  The effects of ionic strength (0, 0.3, and 0.6 M KCl) and temperature (4 and 25 °C) on the interaction between fish myoglobin and myofibrillar proteins were investigated in a model system. Increases in the relative content of bound myoglobin and metmyoglobin formation in myoglobin-natural actomyosin (NAM) mixtures with concurrent decreases in whiteness and Ca²⁺-ATPase activity were observed with increasing ionic strength ( P < 0.05). The relative content of bound myoglobin and the oxidation of oxymyoglobin were generally greater at 25 °C than at 4 °C ( P < 0.05). Binding of myoglobin to NAM resulted in decreased whiteness ( P < 0.05). Ca²⁺-ATPase was not affected by temperature ( P > 0.05). SDS-PAGE patterns of protein samples suggested that myoglobin-NAM interactions did not involve disulfide bonds. The formation of high-molecular-weight aggregates (>206 kDa) was observed and was more pronounced at higher ionic strength and higher temperature.