转谷氨酰胺酶聚合改性大豆分离蛋白的功能特性研究

研究了转谷氨酰胺酶(MTGase)聚合改性大豆分离蛋白的持水性、吸油性、溶解性、乳化性、发泡性及凝胶强度等功能特性。结果显示,与大豆分离蛋白相比,MTGase改性的大豆分离蛋白(MSPI)具有更高的凝胶性和乳化稳定性,但其溶解性、持水性、吸油性、起泡性与泡沫稳定性和乳化性明显减弱。     

花生分离蛋白磷酸化改性研究

采用响应面优化法对花生分离蛋白进行磷酸化改性,以氮溶解指数(NSI)为指标得出花生分离蛋白磷酸化改性的最佳条件为三聚磷酸钠添加量7.77%、花生分离蛋白质量分数6.38%、反应温度44.85℃、反应体系pH8.24、反应时间5.68h。得到的花生改性蛋白NSI 最大值为77.74%。改性后,花生分离蛋白的吸油性、吸水性、持水性、乳化性、乳化稳定性、泡沫稳定性都有不同程度的提高。     

谷氨酰胺转氨酶介导的荞麦蛋白-花生蛋白交联及其功能特性研究

该文以谷氨酰胺转氨酶（TGase）为交联酶制剂,对荞麦蛋白与花生蛋白进行交联,通过单因素试验对两种蛋白的比例、总蛋白质浓度、TG酶添加量、交联温度、交联时间和pH进行了参数优化,并研究了最佳交联工艺条件下制备得到的交联产物的功能特性。结果表明,荞麦蛋白与花生蛋白的质量比1:1 (g:g)、总蛋白浓度4%、加酶量1.25%、反应温度40℃、反应时间120 min、pH 8.0时的交联反应效果最佳,交联度为63.1%。功能特性测定结果表明,与未交联的蛋白质相比,交联后的蛋白质的持水性、持油性和乳化稳定性有所提高,但乳化性、起泡性和起泡稳定性降低;在pH 3~12范围,交联蛋白质的溶解度逐渐升高,尤其在pI 4.0处,溶解度提高最为显著。     

酶法改性对米糠蛋白凝胶硬度及功能性质的影响

以米糠蛋白为原料,采用转谷氨酰胺酶(TG)将其改性,通过单因素试验和响应面优化试验研究蛋白质质量分数、改性时间及加酶量对改性的米糠蛋白凝胶硬度的影响,并比较改性前、后米糠蛋白的溶解性、乳化性和乳化稳定性、起泡性和起泡稳定性以及持油性等功能性质。结果表明,在蛋白质质量分数12.8%,改性时间3.2 h,加酶量19.7 U/g的条件下得到蛋白质最佳凝胶硬度,即93.58 g。经改性处理后蛋白质持水力增加162%,溶解度增加31.1%,乳化性和乳化稳定性分别提高52.7%,25.4%,起泡性和泡沫稳定性分别提高33.3%,7.2%,持油性提高114%。用扫描电子显微镜观察其微观结构,发现改性的米糠蛋白呈类似海绵结构,其结构有较明显的改善,说明酶法改性米糠蛋白效果显著。     

两种方法提取花生蛋白功能特性的对比研究

试验旨在对比水相酶法与碱提法提取冷榨花生饼粕中蛋白质的功能特性,为食品及饲料行业更好的利用花生蛋白提供参考。研究结果表明,在相同条件下,利用水相酶法提取的花生水解蛋白的乳化性、乳化稳定性、起泡性、吸油性和持水性与花生碱提蛋白相比都有很大改善;提升最大幅度分别为:乳化性11.05%、乳化稳定性34.31%、起泡性33.94%、吸油性0.042 g/g、持水性1.323 g/g;但水解蛋白的泡沫稳定性比碱提蛋白稍差。通过对比两种方法提取蛋白质的功能特性,制取高品质的花生蛋白质宜采用水相酶法。     

谷氨酰胺转氨酶对小麦蛋白凝胶性的影响研究

通过单因素及响应面试验研究了谷氨酰胺转氨酶(TG酶)对小麦蛋白凝胶性的改善作用,探讨了小麦蛋白浓度、TG酶浓度、反应温度、反应时间和反应p H对其凝胶特性的影响。结果表明,小麦蛋白质量浓度为20 g/100 m L,TG酶用量14 U/g小麦蛋白,p H 7.0,30℃反应30 min时,谷氨酰胺转氨酶对小麦蛋白的凝胶性改善效果最强,凝胶强度最大值达到120.099 g/cm2,比未改性小麦蛋白提高55.5%。同时乳化性、起泡性显著增加,分别比未改性提高83%和56.25%;起泡稳定性和保水性分别比改性前小麦蛋白提高5%和8.5%,但是溶解度和乳化稳定性分别比改性前降低9.91%和12.41%。     

两种干燥方式对亚麻籽分离蛋白功能性质的影响研究

以亚麻籽冷榨饼为原料,采用真空冷冻干燥和喷雾干燥两种方式制备分离蛋白,研究两种干燥方式对亚麻籽分离蛋白功能性质的影响。结果表明:真空冷冻干燥亚麻籽分离蛋白的溶解性、持水性、吸油性、乳化性、乳化稳定性和泡沫稳定性均高于喷雾干燥亚麻籽分离蛋白,而后者的起泡性高于前者。在中性条件下真空冷冻干燥和喷雾干燥亚麻籽分离蛋白的持水性分别为6.75 g/g和5.74 g/g;亚麻籽分离蛋白吸油性较好,在30℃时,喷雾干燥亚麻籽分离蛋白的吸油性为1.91 g/g,冷冻干燥亚麻籽分离蛋白是其3.09倍。亚麻籽分离蛋白的持水性、乳化性和乳化稳定性随着p H的变化曲线与溶解性相似,均在p H 4时最小。     

蛋白质谷氨酰胺酶对米谷蛋白功能性质的影响

研究蛋白质谷氨酰胺酶对米谷蛋白功能性质的影响,测定米谷蛋白及其脱酰胺样品的溶解度、乳化、起泡、黏度、持水持油力等功能性质。结果表明,谷氨酰胺酶法脱酰胺的米谷蛋白其功能性质均有提高,在中性溶液中溶解度显著增加(达到96.99%);酶解时间1～12h 的范围内,改性蛋白在中性条件下的乳化性能最好,酶解时间1～5h 的范围内,强酸性条件下的乳化稳定性得到显著改善,并呈现出最佳的起泡性能,而起泡稳定性和黏度则随着反应时间的增加均逐渐降低;此外,改性蛋白与未改性蛋白比较,持水性提高1.75～2.03 倍,持油性提高1.58～1.94 倍。     

谷氨酰胺转胺酶改性对花生分离蛋白某些功能性质的影响

利用微生物产谷氨酰胺转胺酶(MTG)对花生分离蛋白(PPI)进行改性,结果表明:加酶量、pH、反应温度、反应时间和底物蛋白浓度对PPI改性具有显著影响.通过单因素和正交实验得出凝胶性的最佳改性条件为:加酶量10U/g;最适pH7;反应温度50%;反应时间3h;反应底物浓度15%.改性后花生分离蛋白的凝胶性比对照提高了279%,溶解性和乳化性分别降低了44%和31%,乳化稳定性提高了8.5%.     

南瓜籽分离蛋白功能性研究

以亚临界流体萃取南瓜籽油后的粕为原料,采用碱溶酸沉法制得南瓜籽分离蛋白,研究南瓜籽分离蛋白的溶解性、持水性、乳化性、起泡性、吸油性等功能特性。结果表明:南瓜籽分离蛋白的等电点为p H 5,在等电点时蛋白质功能特性较差,溶解性最小为4.25%,持水性仅为1.85 g/g,乳化性最弱,乳化性和乳化稳定性分别为52%、38%,起泡性和泡沫稳定性分别为5.77%、33.33%;在强酸和强碱环境中,南瓜籽分离蛋白功能特性较好,溶解性大,达到94.5%,最大持水性为6.33 g/g,最大乳化性和乳化稳定性分别为70%、94%,最大起泡性和泡沫稳定性分别为28.3%、93.33%,最大吸油性为2.33 g/g。     

亚硫酸钠对花生浓缩蛋白功能性质的影响

研究了亚硫酸钠浓度和处理时间对花生浓缩蛋白各项功能性质(溶解性、乳化活性及乳化稳定性、起泡性及泡沫稳定性、吸水性、持油性和凝胶性质)的影响。结果表明:经过亚硫酸钠的处理,花生浓缩蛋白各项功能性质显著改善;亚硫酸钠改性的最优条件为亚硫酸钠浓度0.75mmol/L,处理时间120min。亚硫酸钠处理能够有效改善花生浓缩蛋白的功能性质,是可行的花生浓缩蛋白改性办法。      

谷氨酰胺转氨酶改性菜籽蛋白凝胶特性的研究

为改善菜籽蛋白质的凝胶特性,采用谷氨酰胺转氨酶(TG)以单因素试验和正交试验研究影响菜籽分离蛋白(RPI)凝胶特性的主要因素-- TG 质量浓度、pH 值、反应温度和反应时间。结果表明：反应温度和 pH 值对菜籽分离蛋白凝胶性的影响显著,同时得到谷氨酰胺转氨酶改性菜籽蛋白凝胶特性的最佳工艺条件,RPI 质量浓度1.5g/10mL、加酶量50U/g RPI、pH9.0、反应温度40℃、反应时间20min。     

Maleic anhydride derivatives of a protein isolate: preparation and functional evaluation

African locust bean protein isolate (NPI) was acylated with maleic anhydride at various concentrations. Addition of maleic anhydride at the levels of 0.1, 0.5 and 1.0 g/g of protein produced 36.4% (MP1), 43.7% (MP2) and 73.6% (MP3) of maleylated protein isolate, respectively. Water absorption capacity increased after maleylation but oil absorption capacity reduced progressively with increase in level of modification. Results also revealed that gelation capacities reduced after protein modifications. Emulsifying activity (EA) and emulsion stability (ES) increased following protein modification. In addition, corresponding increases in emulsifying properties were observed with increase in degree of modification of the proteins. Maleylation improved the foaming capacity of the native protein. Foaming capacity increased with increases in protein concentration for both native and maleylated protein derivatives while progressive decline in foam stability occurred with increases in level of protein modification.     

Structural and rheology properties of pea protein isolate-stabilised emulsion gel: Effect of crosslinking with transglutaminase

The microstructures and characteristics (water holding capacity (WHC) and rheological properties) of pea protein isolate (PPI) emulsion gels produced via transglutaminase (TGase) with different oil-weight fractions (φ, 20%~50%) were studied in the present work. The results showed that the WHC and gel strength (storage modulus) of PPI emulsion gel were raised with increasing of φ. Simultaneously, the proteins entrapped within the network gradually increase due to the enzymatic treatment, which resulted in a tighter internal structure of emulsion gel. At high oil-weight fractions (e.g. 50%), the network of the emulsion was essentially a coarse chain of particulate, mainly forming a ‘close-knit’ oil droplet. Therefore, the gelation mechanism is related to the state of proteins in the system, which are divided into proteins adsorbed and unadsorbed on the interface. The results will be of significant assistance in comprehending the theories of the gelation process and the protein emulsion gels immobilisation by the enzyme.     

Emulsifying properties of the transglutaminase-treated crosslinked product between peanut protein and fish (Decapterus maruadsi) protein hydrolysates

BACKGROUND: Defatted peanut meal, a protein‐rich by‐product from the oil extraction industry, is underutilised owing to its inferior functional properties. In this study, transglutaminase (TGase) crosslinking and proteolysis were used to improve the emulsifying properties of peanut protein isolate (PPI) extracted from the meal. PPI and PPI hydrolysate (PPIH) were conjugated separately with fish (Decapterus maruadsi) protein hydrolysate (DPH), catalysed by TGase to obtain improvements in the emulsifying properties. RESULTS: Analyses by electrophoresis and high‐performance liquid chromatography indicated that polymers were formed in all TGase‐treated samples. In emulsions of PPIH, PPI‐DPH and PPIH‐DPH the volume/surface average particle diameter (d₃₂), creaming and instability phenomenon were decreased and the zeta‐potential was increased after TGase treatment, showing improved emulsifying activity and emulsion stability. In the case of PPI, TGase treatment had no effect on the emulsifying activity, but the emulsion stability of TGase‐treated PPI was improved. CONCLUSION: The study showed that TGase crosslinking and proteolysis could improve the emulsifying properties of PPI, while proteolysis followed by TGase crosslinking proved more efficient. The emulsifying properties of the heterologous protein systems of PPI‐DPH and PPIH‐DPH were also improved by TGase treatment. Copyright © 2010 Society of Chemical Industry     

谷氨酰胺转氨酶预交联改善CaSO4诱导大豆分离蛋白凝胶性的研究

酶法改性能够有效提升大豆蛋白的凝胶性。为了探讨谷氨酰胺转氨酶(transglutaminase, TGase)预交联对盐诱导大豆分离蛋白凝胶性的影响,通过控制酶浓度、预交联时间制备不同预交联程度的大豆分离蛋白(soy protein isolate,SPI)溶液,并研究其在CaSO₄作用下的成胶性能。结果显示,与未经TGase处理的SPI相比,TGase适度预交联能够显著提升SPI的凝胶品质。经3～5 U/g TGase预交联20 min或3 U/g TGase预交联20～30 min后,SPI凝胶性得到了不同程度的提升,其中弹性模量、屈服应力、屈服应变、持水率最大分别提高了124.5%、269.0%、135.0%及53.0%。然而,过度预交联产生过大的蛋白聚集体,导致最终形成的凝胶结构粗糙、多孔,凝胶强度、持水力等均显著下降(P<0.05)。由此可见,合理利用TGase对蛋白进行预交联处理能够改善SPI凝胶制品品质,对于TGase在食品工业中的应用及传统豆制品质构改良具有重要的指导意义。     

Functional properties and structural characteristics of phosphorylated pea protein isolate

In order to expand the application of pea proteins in the food industry, pea protein isolate (PPI) was chemically phosphorylated to improve its functional properties. Based on the comprehensive membership value (CMV) degree, the optimal condition for PPI phosphorylation modification was as follows: pH 12, modification temperature at 70 °C and an addition of 7.0% (w/v) sodium tripolyphosphate (STP). Under this condition, the solubility, emulsifying property, emulsifying stability, foaming property and oil absorption capacity of the modified PPI were improved substantially. In addition, the structure of modified PPI was characterised by scanning electron microscope (SEM) and Fourier transform infrared (FTIR) spectroscopy. The results showed that the modified PPI had a smooth and uniform lamellar structure, where the content of α-helix and β-sheet structure increased, but the content of β-corner and random coil structure decreased. The thermodynamic properties were analysed by differential scanning calorimetry (DSC) and the results showed that ∆H of the modified PPI increased significantly. Finally, the optimum phosphorylated PPI was mixed with 0.4% (w/v) xanthan gum to form PPI fat mimics (PPI-FM). PPI-FM was added into mango mousse cake to reduce the amount of light cream, and the result showed up to 20% of light cream could be substituted.     

Effect of peanut protein isolate on functional properties of chicken salt-soluble proteins from breast and thigh muscles during heat-induced gelation

In this study, we investigated the impact of peanut protein isolate (PPI) on the functional properties of chicken salt-soluble protein (SSP) prepared from breast and thigh muscles during heat-induced gelation. The addition of PPI increased the water-holding capacity, gel strength and elasticity of heat-induced chicken SSP mixed gel. Breast and thigh SSP had the best gel properties at the addition of 2.5% and 3.5% PPI, respectively. Rheology indicated that thigh SSP showed higher storage modulus (G') than breast SSP. Differential scanning calorimetry showed that the addition of PPI changed transition temperatures (Tmax) and enthalpy of denaturation (ΔH) of chicken SSP. Scanning electron microscopy indicated that the PPI-treated SSP gels had more compact ultrastructures than controls. The results suggested that PPI may be a potential protein additive for improve the characteristics of SSP gelations.     

固定化酶改性酸法大豆浓缩蛋白在猪肉肠中应用的研究

利用固定化谷氨酰胺转氨酶(MTG)对酸法大豆浓缩蛋白(SPC)进行改性,并将改性SPC应用于猪肉肠.试验表明:改性后SPC的持水性和吸油性分别比未改性SPC提高了24.8%和64.5%;与大豆分离蛋白(SPI)相比,其凝胶性和吸油性分别高出58.3%和27.0%,持水性则降低8.0%.改性后的SPC用于猪肉肠中,当添加量为6%时,猪肉肠的咀嚼性比未改性SPC和SPI分别提高了418.6%和187.1%;得率比未改性SPC和SPI分别提高了18.9%和4.8%,感官评分结果也与其相一致.