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为了研究超声波联合酶技术提高大豆分离蛋白(Soybean Protein Isolated,SPI)在酸性条件下(pH 4)乳化性能的效果,本文以大豆分离蛋白为原料,以乳化性能和乳状液粒径为衡量指标,确定超声波联合植酸酶-酸性蛋白酶(Ultrasound combined with phytase-acidic protease,Uphy-aci)改性方法的最适宜条件。研究发现,当SPI浓度6%,植酸酶添加量4 U/g,酸性蛋白酶添加量1500U/g,植酸酶与酸性蛋白酶的酶解时间分别为50 min和30 min时,改性后的SPI(pH 4)乳化性能明显增加,乳状液粒度减小;通过表面疏水性(H0)和扫描电镜(SEM)分析了超声波-酶复合改性处理的SPI,发现在酸性条件下,SPI表面疏水性含量为487.78,比未改性提高了71.2%,并呈现破碎均一、多孔的微观结构。因此,超声波与植酸酶-酸性蛋白酶联合改性提高酸性条件下SPI的乳化特性等功能性质,并且拓宽了大豆分离蛋白的应用领域。 相似文献
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利用微生物谷氨酰胺转胺酶(MTG)对大豆分离蛋白(SPI)进行改性,结果表明:SPI浓度、MTG浓度、反应温度、反应时间和pH值对SPI改性具有显著影响。改性SPI的凝胶性为11.6kcp,比对照提高了1833%。十二烷基硫酸钠-聚丙稀酰胺凝胶电泳结果表明,经MTG改性,SPI可在分子间生成共价键,形成相对分子量较大的聚合物,从而增加了SPI的凝胶性。 相似文献
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大豆分离蛋白的磷酸化改性及功能性质的研究 总被引:19,自引:0,他引:19
采用三聚磷酸钠 (STP)对大豆分离蛋白 (SPI)进行化学改性 ,运用三因素二次饱和试验设计 ,得出最优试验回归方程为 :Y =2 8 2 6+5 89X1+0 93X2 +0 83X3-0 1 5 7X12 -1 2 6X2 2 +2 2 6X32 +0 65X1X2 -0 1 5X1X3+0 3 8X2 X3。并得出 6%大豆分离蛋白磷酸化程度最大的工艺条件是 pH 8 0 ,STP浓度为 3 %,45℃下反应 4h。同时研究了改性前后不同程度下SPI的功能性的变化 ,结果表明 ,改性后的SPI的溶解性、乳化能力、持水能力以及粘度等均有很大的提高 ,而发泡性无明显改善。通过红外光谱检测证明 ,STP与SPI反应是赖氨酸残基所进行的磷酸酯化反应。 相似文献
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酰化对大豆分离蛋白乳化性能的影响 总被引:2,自引:0,他引:2
目的:研究化学改性对大豆分离蛋白(SPI)乳化性能的影响;方法:采用乙酸酐和琥珀酸酐对SPI进行化学改性;结果:随酰化试剂用量的增大,酰化程度不断提高,在相同酰化试剂用量的条件下,乙酰化程度高于琥珀酰化.SPI的乳化活性指数(EAI)和乳化稳定性(ES)都随酰化程度的增大而增大.在中性和弱碱性(pH 5.0~9.0)范围内,酰化明显提高了SPI的EAI和ES.琥珀酰化的改性效果优于乙酰化;不过离子强度削弱了SPI的EAI和Es;结论:酰化可有效提高SPI的乳化性能,其中琥珀酰化的改性效果优于乙酰化. 相似文献
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Janesca A. Roman & Valdemiro C. Sgarbieri 《International Journal of Food Science & Technology》2006,41(6):609-617
The hydrophilic and surfactant properties of casein concentrates made by different processes such as isoelectric precipitation and neutralization (commercial casein, CC) coagulation by rennet (casein clots, COC) and microfiltration/diafiltration (casein micelles, CM) were studied. Water absorption capacity (WAC), water solubility (WS) and water‐holding capacity (WHC) were highest for CM and lowest for COC. Solubility was higher in water and in pH 5.5, 0.10 m NaCl solution for both CM and COC. Foaming capacity was better for CM than for CC at pH 4.0 and for CC at pH 6.0 and 8.0. Foam stability was low for both CM and CC at pH 4.0 but it was high for CM at pH 6.0 and 8.0 and for CC in the absence of salt. Emulsifying capacity was higher for CC at pH 4.0 and 7.0. Stability of emulsion was high for CC at pH 4.0 and for CM at pH 7.0. 相似文献
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Functional properties of 8S globulin fractions from 15 mung bean (Vigna radiata (L.) Wilczek) cultivars 下载免费PDF全文
Hong Liu Hongkai Liu Lei Yan Xuzhen Cheng Yufan Kang 《International Journal of Food Science & Technology》2015,50(5):1206-1214
The functional properties including solubility, water absorption capacity, oil absorption capacity, foaming properties and emulsifying properties of 8S globulin fractions from 15 mung bean cultivars were investigated in this study. In addition, the effects of pH on solubility, foaming properties and emulsifying properties were studied. The functional properties of the 8S globulin fractions varied significantly among the different mung bean varieties and exhibited better performance in solubility and emulsion stability compared with soya bean 7S protein. A negative correlation was found between water absorption capacity and oil absorption capacity. Remarkable differences in polypeptides constituents were observed in 8S globulin fractions, and the ratio of 11S/8S globulins has a positive effect on water absorption capacity while a negative effect on oil absorption capacity. As a function of pH, the emulsifying activity indexes of the 8S globulin fractions were found to be distinctly dependent on the solubility, while no significant correlation was found between the emulsifying stability and solubility, nor between the foaming properties and solubility. The foaming capacity showed a strong correlation with foam stability. 相似文献
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Functional properties (gel strength, cold and hot water absorption, solubility in cold and hot water, water holding capacity and pH) were determined for some meat emulsion extenders‐ buttermilk powder, corn starch, microcrystalline cellulose, modified com starch, modified wheat flour, soy‐protein concentrate and whey‐protein concentrate. For these extenders, pH varied from 5.02 to 6.73, water holding capacity from 0.14 to 0.55, gel strength from 0.01 to 5.38 N, cold water solubility from 0.002 to 0.874, hot water solubility from 0.0004 to 0.8755, cold water absorption from 0.9 to 12.3, and hot water absorption from 3.4 to 12.3. 相似文献
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ABSTRACT: Structural changes and functional properties of threadfin bream (Nemipterus sp.) sarcoplasmic proteins (TB-SP) subjected to various pH conditions (pH 3, 5, 6.3, 9, and 12) after subsequent pH readjustment to pH 7 were investigated. Fourier transform infrared spectroscopy revealed the loss of α-helical and β-sheet structures of TB-SP after being subjected to pH 3 or pH 12 treatments. The extent of structural and conformational changes of TB-SP subjected to pH 3 was greater than alkaline pHs (pH 9, 12) and pH 5, respectively. The water holding capacity of lyophilized TB-SP treated at pH 3 and pH 12 increased about 6.5- and 5.4-fold, respectively, as compared to the crude counterpart. Both acid and alkaline pH treatments increased fat absorption capacity of lyophilized sample about 2-fold, but drastically decreased its solubility. The water soluble fraction of extremely acidic (pH 3→7) and alkaline (pH 12→7) samples exhibited higher oil binding capacity as measured by diphenylhexatriene fluorescence and emulsifying activity. A gel-like structure was formed when water-soluble fraction of crude TB-SP and those subjected to moderate pHs (pH 5, 9) at 2 mg/mL was prepared for the emulsion containing 50% oil (v/v). Functional properties of TB-SP varied, depending on the pH-adjustment process applied. 相似文献
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E H Rahma 《Die Nahrung》1988,32(6):577-583
Faba beans (Vicia faba) were germinated at room temperature for 3 and 6 days respectively. The effect of germination on the protein fractions, protein solubility index, PAGE pattern and some functional properties i.e. emulsification capacity (EC), foaming capacity (FC), foam stability (FS), water and fat absorption capacities of the flour was studied. Germination decreased albumins, globulins and prolamins at different levels but non protein nitrogen and glutelins were increased. The protein solubility index was high at both extreme pH values with an isoelectric point (IP) at pH of 4.4-4.5. The solubility of the protein slightly increased due to germination at all the pH values. PAGE pattern revealed on obvious dissociation and utilization for both fast and slow moving protein fractions during germination. Emulsification and foaming properties vs pH profile were similar to the pattern of solubility vs pH. Both properties were high at acidic and alkaline pH's and the minimum values were at pH 4 to 5. Germination process improved EC, FC and FS of the flour in comparison with that of dry bean flour. Water absorption of faba bean flours was improved during germination but the fat absorption markedly decreased. 相似文献
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以兔皮胶原蛋白为原料,对其加工特性进行系统研究。结果表明,兔皮胶原蛋白具有较强的吸水性,达到14.89 m L/g;其在酸性环境中有很高的溶解性,在p H值为3时,溶解度最高,在碱性环境中溶解度降至50%左右;离子质量浓度对胶原蛋白的溶解度有明显影响,其在Na Cl质量浓度为0~2 g/100 m L时保持相对稳定,在Na Cl质量浓度由2 g/100 m L增加至4 g/100 m L过程中急剧下降,而Na Cl质量浓度大于4 g/100 m L后,胶原蛋白溶解度变化不再明显;当胶原蛋白的质量浓度小于1 g/100 m L时,兔皮胶原蛋白的乳化性随着胶原蛋白质量浓度的增加逐渐增加,但质量浓度超过1 g/100 m L时,乳化性降低,乳化稳定性随胶原蛋白质量浓度的变化呈现与乳化性相反的趋势;低质量浓度的胶原蛋白溶液在p H 3~6过程中,乳化性和乳化稳定性均呈下降趋势,随后,p H 6~9时乳化性和乳化稳定性缓慢增加后保持稳定;离子质量浓度在0.00~7.02 g/100 m L范围内,随离子质量浓度的增加,乳化性呈现出先升高后降低的趋势,而乳化稳定性则呈现先增加随后保持稳定的趋势,在离子质量浓度为5.85 g/100 m L时,胶原蛋白的乳化性与乳化稳定性较好。 相似文献
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The functional properties viz. solubility, water and oil absorption, emulsifying and foaming capacities of the protein isolates prepared from raw and heat processed cashew nut kernels were evaluated. Protein solubility vs. pH profile showed the isoelectric point at pH 5 for both isolates. The isolate prepared from raw cashew nuts showed superior solubility at and above isoelectric point pH. The water and oil absorption capacities of the proteins were slightly improved by heat treatment of cashew nut kernels. The emulsifying capacity of the isolates showed solubility dependent behavior and was better for raw cashew nut protein isolate at pH 5 and above. However, heat treated cashew nut protein isolate presented better foaming capacity at pH 7 and 8 but both isolates showed extremely low foam stability as compared to that of egg albumin. 相似文献
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Mucuna protein concentrate was acylated with succinic and acetic anhydride. The effects of acylation on solubility, water absorption capacity, oil absorption capacity and emulsifying properties were investigated. The pH-dependent solubility profile of unmodified mucuna protein concentrate (U-mpc) showed a decrease in solubility with decrease in pH and resolubilisation at pH values acidic to isoelectric pH (pH 4). Apart from pH 2, both acetylated mucuna protein concentrates (A-mpc) and succinylated mucuna protein concentrate (S-mpc) had improved solubility over the unmodified derivative. Acylation increased the water absorption capacity (WAC) at all levels of ionic strength (0.1-1.0 M). WAC of the protein samples increased with increase in ionic strength up to 0.2 M after which a decline occurred with increase in ionic strength from 0.4-1.0 M. When protein solutions were prepared in salts of various ions, increase in WAC followed the Hofmeister series in the order: NaSCN < NaClO4 < NaI < NaBr < NaCl < Na2SO. Acetylation improved the oil absorption capacity while the lipophilic tendency reduced the following succinylation. Emulsifying capacity increased with increase in concentration up to 2, 4 and 5% w/v for U-mpc, A-mpc and S-mpc, respectively, after which an increase in concentration reduced the emulsifying capacity. Both acetylation and succinylation significantly (P < 0.05) improved the emulsifying capacity at pH 4-10. Initial increase in ionic strength up to 0.4 M for U-mpc and 0.4 M for A-mpc and S-mpc increased the emulsion capacity progressively. Further increase in ionic strength reduced emulsion capacity (EC). Contrary to the effect of various salts on WAC, increase in EC generally follows the series Na2SO4 < NaCl < NaBr < NaI < NaClO4 < NaSCN. At all levels of ionic strength studied, S-mpc had a better emulsifying activity (EA) than both A-mpc and U-mpc. EA and emulsifying stability (ES) were pH-dependent. Maximum EA and ES were recorded at pH 10. ES of protein derivatives were higher than those of U-mpc in the range of pH 4-10 but lower at pH 2. Studies revealed that both A-mpc and S-mpc had better ES and EA than the unmodified derivative when protein solutions were prepared in salts of various anions. 相似文献