椰子分离蛋白起泡性、黏度及其影响因素的研究

分析了椰子分离蛋白(CPI)起泡性、泡沫稳定性、黏度及pH、离子强度、温度和蛋白质浓度对这些功能特性的影响。结果表明,椰子分离蛋白的起泡性和黏度与大豆分离蛋白(SPI)相近;而pH、离子强度、温度等因素对椰子分离蛋白的起泡性和黏度有显著的影响。在等电点(pH4.5)附近,CPI的起泡性和黏度最小,但却表现出最高的泡沫稳定性(91.25%);低离子强度可以提高椰子分离蛋白的起泡性,但高离子强度使CPI的起泡性、泡沫稳定性和黏度都变小;在70℃时CPI的黏度最大;蛋白质浓度变大时,CPI的黏度也显著增大。     

脱脂椰子种皮的蛋白质功能性质研究

提取了脱脂椰子种皮中的蛋白质,对其功能性质,如溶解性、持水力、乳化性以及蛋白消化率等进行测定。结果表明,提取所得的脱脂椰子种皮蛋白质持水力(1.50 g/g)以及蛋白消化率(25.63%)均较低;pH对脱脂椰子种皮蛋白质的溶解性、起泡性及乳化性的影响较大,在pH4.0时,脱脂椰子种皮蛋白质的溶解性和乳化性最低;而不同浓度的蛋白质起泡性均在pH4.0时最高。     

糖基化大豆分离蛋白制备工艺优化及对其性质的影响

以大豆分离蛋白为试验材料,优化糖基化大豆分离蛋白制备工艺并研究经过葡萄糖处理对大豆分离蛋白溶解度、凝胶强度、乳化性以及热稳定方面的影响。结果表明:糖基化大豆分离蛋白最佳制备工艺为反应温度69.49℃、反应时间46.64 min、糖的添加量10.64%,凝胶强度最高为76.03;在相同p H下,经葡萄糖处理后的大豆分离蛋白溶解度较大,沉淀较少,而未糖基化的大豆分离蛋白沉淀量增加。糖基化处理的大豆分离蛋白乳化稳定性(emulsifying stability,ES)和热稳定性均有所增强。糖基化改性过程可显著提高大豆分离蛋白的溶解性和乳化性能,这为拓宽其在食品工业中的应用提供了理论基础。     

花生多肽的理化性质及抗氧化性质研究

本文研究了pH、温度、蛋白浓度等因素对花生多肽活性的影响,与花生分离蛋白相比,在温度30-80℃和pH值2～12时花生多肽具有较高的溶解性,更好乳化性、起泡性和泡沫稳定性,但有较低的吸水性和吸油性。此外,花生多肽体外抗氧化能力较强,具有较强的还原力、羟自由基清除力、2,2-二苯基苦味苯肼（DPPH）自由基清除力。表明花生多肽具有良好的理化特性和抗氧化性能,可作为功能食品或保健食品主要成分或添加剂。     

椰麸组分蛋白的氨基酸组成、结构与乳化性分析

为提高椰子加工副产物的利用,本研究从椰麸中依次提取4种组分蛋白,包括清蛋白、球蛋白、谷蛋白-1和谷蛋白-2.分析这4种组分蛋白的氨基酸组成,并利用SDS-PAGE技术分析其亚基组成和分子量.同时分析其表面疏水性,并研究不同离子强度对椰麸各组分蛋白的乳化性和乳化稳定性的影响.结果表明,椰麸蛋白质中清单白、球蛋白、谷蛋白-...     

大豆乳清蛋白的热促凝聚及其对分离蛋白功能性的影响

分别在pH8.0和pH4.5对"碱提酸沉"法制备大豆分离蛋白过程中所得提取液进行热处理,研究了大豆乳清蛋白的热促凝聚效果及其对所制备分离蛋白功能性的影响。结果表明:加热处理可降低大豆乳清中乳清蛋白的含量,在pH8.0和pH4.5时提取液经70℃加热10 min分别使25.7%和40%乳清蛋白转移到分离蛋白产品中。以普通分离蛋白为对照,对3种分离蛋白产品进行功能性分析,发现3种产品均在pH4.5~4.8的范围内溶解度最小,70℃加热10 min所制备分离蛋白的持水性明显高于普通分离蛋白,但其持油性、起泡性、泡沫稳定性和乳化性均低于普通分离蛋白,而乳化稳定性无显著差异。     

提取方法对脱脂松仁粕蛋白性质的影响

以脱脂松仁粕为原料,比较提取方法对蛋白性质的影响。采用Osboren分级提取各组分蛋白,并与碱法提取的蛋白进行理化性质与功能性质的比较。研究不同蛋白的等电点、热变性温度、氨基酸组成、十二烷基硫酸钠-聚丙烯酰胺凝胶电泳(sodium dodecyl sulfate-polyacrylamide gelelectrophoresis,SDS-PAGE)及不同蛋白的溶解性、起泡性和起泡稳定性、乳化性和乳化稳定性。结果表明:Osboren提取的清蛋白、球蛋白、谷蛋白的蛋白质含量分别为77.87%、68.23%、79.05%,碱法提取的蛋白含量为83.50%;四种蛋白的等电点为3.4、3.8、3.6、4.0,热变性温度为94℃、81℃、95℃、112℃;四种蛋白的必需氨基酸组成基本合理,主要含有谷氨酸与精氨酸;SDS-PAGE分析得出四种蛋白的条带有差别但主要集中在9.31~41.32ku;除乳化性和乳化稳定性以碱法提取的蛋白最好外,其余加工性质清蛋白均为最好。由此可见不同的提取方法对SDS-PAGE、热变性温度及加工性质均有不同的影响。     

大豆分离蛋白酶解产物功能特性的研究

研究了大豆分离蛋白的碱性蛋白酶和木瓜蛋白酶水解产物各种加工功能性质的变化趋势,并比较了两种酶在各个不同酶解时间下水解产物的各种功能性质。结果表明:大豆分离蛋白酶解产物比大豆分离蛋白的溶解性、乳化性、发泡能力和吸油性都有所改善;大豆分离蛋白木瓜蛋白酶水解产物保水性、乳化性、吸油性、发泡能力、粘度、凝胶性均优于大豆分离蛋白碱性蛋白酶水解产物。     

双氧水脱色对油茶粕蛋白结构和功能特性的影响

为了除去油茶粕蛋白的色素,添加体积分数为4%的双氧水在40℃下作用蛋白提取液1h可取得较好的脱色效果,但双氧水脱色对油茶粕蛋白结构和功能的影响需要进一步研究。本文通过测定变性温度、表面疏水性和巯基的含量,分析红外光谱、X射线衍射峰、微观形貌等研究脱色前后油茶粕蛋白结构和功能的变化。结果显示:双氧水脱色使油茶粕蛋白的表面疏水性上升,巯基含量下降,二硫键含量基本不变;通过红外光谱分析,双氧水脱色减弱了油茶粕蛋白化学键强度,但没有影响油茶粕蛋白基本骨架,微观结构基本相似,油茶粕蛋白的X射线衍射峰的位置和强度基本一致,热变性温度升高,双氧水没有改变油茶粕蛋白的等电点,但油茶粕蛋白的溶解度、乳化性、乳化稳定性、起泡能力和泡沫稳定性均下降,持油性和持水性上升。本研究结果表明双氧水脱色未明显改变油茶粕蛋白的结构,但其功能性质受到一定影响。     

大豆原料对分离蛋白加工及功能特性的影响

为研究不同大豆品种对大豆分离蛋白加工及功能特性的影响,选取了5个品种的大豆为原料,对比分析了原料对大豆分离蛋白得率、粗蛋白含量、凝胶特性、持水性、乳化特性的影响。结果显示,以冀豆12为原料制备的大豆分离蛋白得率最高,五星4最低;采用质构分析法对凝胶特性进行分析,以冀豆12为原料生产的大豆分离蛋白的凝胶强度值最高,五星3号最低;持水性最高为冀豆12,最低为五星3号;乳化性最高为五星3号,与冀豆12相差不大,乳化性最低为冀豆20。综上,以冀豆12为原料制备的大豆分离蛋白具备极高的持水性、凝胶特性和极佳的乳化特性,冀豆12适合高凝胶、高持水力、高乳化性的大豆分离蛋白的生产。     

大豆蛋白乳化性研究进展

大豆蛋白质具有较高的营养价值及功能特性,是某些食品加工中的重要原料。乳化性是蛋白质的一种重要功能性质,它应包括乳化容量和乳化稳定性两种特性。本文探讨了大豆蛋白乳化性的研究进展,分析了我国大豆蛋白乳化性的研究现状。     

Composition and functional properties of protein isolates obtained from commercial legumes grown in northern Spain

Pea (Pisum sativum), faba bean (Vicia faba) and soybean (Glycine max) seeds were characterized, and protein isolates were prepared following an isoelectric point precipitation procedure. Soybean seeds showed the highest protein content (36.7%) and carbohydrate was the major constituent in the pea (59.4%) and the faba bean seeds (52.1%). Protein contents were higher than 80% in all the protein isolates. The amino acid contents in the protein isolates were, in general, higher than those in their own starting seeds. The antinutritional factor contents were reduced after the protein isolate preparation. The highest reductions achieved for tannins were 95% in the faba bean protein isolate, and for phytates (45%) and trypsin inhibitor activity (46%) in the pea protein isolate. Haemagglutinating activity was not detected in any of the protein isolates. Minimum solubility values were observed at a pH range between 4.0 and 6.0, and maximal solubilities were obtained at basic pH values. The faba bean protein isolate showed the highest water and oil absorption capacities, and the best gelling properties. The soybean protein isolate had the best foam expansion capacity. Thus, the protein isolates had an improvement in some of the characteristics compared to their original seeds with lower contents in tannins, phytates and haemagglutinating activity, but had weak functional properties.     

Functional and Rheological Properties of Amaranth Albumins Extracted From Two Mexican Varieties

The functional and rheological properties of amaranth albumins isolates extracted from two new Mexican varieties were determined. Functional properties tested were protein solubility, foaming, water and oil absorption capacities, emulsifying activity, and emulsion stability. The maximum solubility values for both amaranth albumins were found above pH 6 and values were compared to the solubility of egg albumins. Albumins from amaranth showed excellent foaming capacity and foaming stability at pH 5, suggesting that this protein could be used as whipping agents as egg albumins, also the water and oil absorption capacities reached their maximum values at acidic pH, suggesting that amaranth albumins could be appropriate in preparation of acidic foods. The rheological test based on farinograms and alveograms showed that wheat flour supplemented with 1% amaranth albumins improves the dough properties due to higher mixing stability and the bread had better crumb characteristics. In addition of the known high nutritional values of amaranth albumins, our results indicate the high potential for use of these proteins as an ingredient in food preparations.     

Oat protein solubility and emulsion properties improved by enzymatic deamidation

Oat protein produced by a dry milling process was enzymatically deamidated by a food-grade protein-glutaminase (PG), and the effects on structure, solubility and emulsifying properties of oat proteins were studied. The reactions were conducted at neutral pH and low salt concentration conditions. Oat proteins were deamidated up to a deamidation degree of 59%. The solubility of proteins doubled. Oil-in-water emulsions prepared with the native and deamidated oat proteins differed as the emulsions prepared from oat proteins with high deamidation degree had a more uniform oil droplet particle size and longer stability. Fourier transform infrared (FT-IR) analysis demonstrated that oat protein secondary structure became more flexible by deamidation. Protein-glutaminase mediated deamidation appeared to be a promising technique to improve oat protein functionality such as emulsifying ability and solubility.     

超声波对大豆蛋白增溶作用的研究

为了提高大豆深加工产品的得率和蛋白质含量，利用超声波处理大豆经湿磨后的浆潭混合液态物，产生超声空化效应，提高大豆蛋白的溶出率，减少大豆蛋白在豆渣中的残留，试验表明：超声提取技术能提高大豆蛋白的溶出率，从而使豆乳蛋白含量相对提高6.6%，豆乳干物质重量相对提高11.6%。该技术对于传统大豆制品及现代大豆加工新产品如豆奶、速溶豆粉及分离蛋白、农缩蛋白等产品的生产均具有提高蛋白含量、增加得率的效用。     

马铃薯浓缩蛋白制品的功能性质评价

实验主要比较了马铃薯全蛋白粉、HCL沉淀蛋白 ,FeCl3沉淀蛋白、大豆分离蛋白以及酪蛋白的溶解度、乳化力和起泡力。结果得出上述各种蛋白制品中蛋白质在pH 8 0时的溶解度分别为 70 %、 2 7%、 6 5%、 97%和 90 % ;马铃薯全蛋白粉的乳化力和起泡力与大豆分离蛋白相当     

Effects of a Fish Oil Rich in Docosahexaenoic Acid on Cardiometabolic Risk Factors and Oxidative Stress in Healthy Rats

Omega-3 polyunsaturated fatty acids are associated with a lower risk of cardiometabolic diseases. However, docosahexaenoic acid (DHA) is easily oxidized, leading to cellular damage. The present study examined the effects of an increased concentration of DHA in fish oil (80% of total fatty acids) on cardiometabolic risk factors and oxidative stress compared to coconut oil, soybean oil, and fish oil containing eicosapentaenoic acid (EPA) and DHA in a balanced ratio. Forty healthy male Sprague–Dawley rats were supplemented with corresponding oil for 10 weeks. Supplementation with the fish oil containing 80% DHA decreased plasma fat, plasma total cholesterol and muscle fat compared to the coconut oil and the soybean oil. Increasing concentrations of DHA induced incorporation of DHA and EPA in cell membranes and tissues along with a decrease in ω-6 arachidonic acid. The increase in DHA promoted lipid peroxidation, protein carbonylation and antioxidant response. Taken together, the increased concentration of DHA in fish oil reduced fat accumulation compared to the coconut oil and the soybean oil. This benefit was accompanied by high lipid peroxidation and subsequent protein carbonylation in plasma and in liver. In our healthy framework, the slightly higher carbonylation found after receiving fish oil containing 80% DHA might be a protecting mechanism, which fit with the general improvement of antioxidant defense observed in those rats.