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。     

响应面法优化物理辅助碱法提取米糠蛋白工艺

比较分析碱法、胶体磨辅助碱法、超声辅助碱法、胶体磨超声辅助碱法对米糠蛋白提取率及纯度的影响。结果表明,胶体磨超声辅助碱法能够显著提高米糠蛋白的提取率,其纯度为74.27%。并以此方法中的超声功率、液料比、超声温度、超声时间为考察因素,蛋白提取率为响应值。通过Design Expert 8.0.6软件做响应面优化分析得,胶体磨超声提取米糠蛋白的最佳工艺为米糠粒径40 目、pH 9、超声功率69 W、工作时间4 s、间歇时间2 s、液料比20∶1（mL/g）、超声时间40 min、超声温度46 ℃,此条件下模型预测蛋白提取率为92.14%。经验证,实际提取率为90.84%,与模型相符。胶体磨超声辅助碱法能够显著地提高米糠蛋白的提取率,且时间短,为米糠蛋白的进一步研究提供参考。     

稻米蛋白提取工艺及其特性研究

以粳稻米为原料,分析其糙米、白米和米糠的营养成分及蛋白组成特点,研究提取条件对糙米、白米和米糠蛋白提取量的影响,并对这三种蛋白的溶解性及分子量分布特征进行比较。结果表明：糙米、白米中的蛋白均以谷蛋白为主,但糙米中谷蛋白含量比白米低4.78%,而清蛋白含量比白米高55.93%;糙米中清蛋白和球蛋白含量分别比米糠低77.22%、44.59%,但谷蛋白含量比米糠高47.00%。提取时间、温度及液料比对三种原料的蛋白提取量均有不同程度的影响,其中液料比是提取三种蛋白时最显著的影响因素 (p ＜ 0.01);温度对白米蛋白提取影响显著(p ＜ 0.05)、对米糠蛋白极显著(p ＜ 0.01),而对糙米蛋白不显著;时间仅对提取白米蛋白有显著影响(p ＜ 0.05),对其他两种蛋白的提取没有明显作用。采用响应面法对提取条件进行优化,得到三个回归模型,经验证,用该模型可以预测稻米蛋白的提取量。稻米蛋白溶解性与SDS-PAGE 电泳分析表明,糙米蛋白的溶解性及其蛋白分子量分布介于白米蛋白与米糠蛋白之间。     

喷射蒸煮处理对米糠蛋白功能特性及体外消化性的影响

研究了喷射蒸煮(HTC)处理对天然米糠蛋白(RBP)与热稳定米糠蛋白(HRBP)提取的影响,并对蛋白的粒度、亚基组成、接枝度、功能性及体外消化性能进行表征。研究表明:HTC处理能显著提高RBP与HRBP的得率(分别从44.9%与14.8%增加到52.2%与44.5%),但对蛋白的纯度没有显著影响。HTC处理后RBP与HRBP的粒度分别从73.6 nm与149.1 nm降低到46.8 nm与96.6 nm,同时生成接枝度28.0%与9.4%的糖基化产物。SDS-PAGE电泳图谱表明,处理后的米糠蛋白生成高分子质量的蛋白聚集体与糖基化产物。HTC处理更有利于HRBP功能性与消化性的提高,且HRBP具有RBP类似的溶解度曲线、起泡能力、泡沫稳定性与良好的乳化能力与消化能力,尽管该处理降低了天然米糠蛋白的消化性。     

Protein Concentrates from Unstabilized and Stabilized Rice Bran: Preparation and Properties

Protein concentrates were prepared from commercially available unstabilized and heat stabilized rice bran by alkaline extraction and isoelectric precipitation. Stabilized rice bran had lower protein extractability at all particle sizes (75μ to 150μ). Both unstabilized rice bran protein concentrate (URBPC) and stabilized rice bran protein concentrate (SRBPC) showed maximum nitrogen solubility at pH 8.0. URBPC (71.5% protein) and SRBPC (50.9% protein) showed differences in amino acid contents. SDS-PAGE of protein concentrates revealed several common components and absence of certain components from SRBPC. Protein denaturation due to commercial heat stabilization impaired extractability of proteins and influenced its quality.     

米糠蛋白提取中褐变抑制剂的筛选

米糠蛋白是一种低过敏性的优质植物性蛋白,但制备过程中常伴随褐变反应的发生,导致制备出的米糠蛋白成品颜色深,限制了米糠蛋白在食品及相关领域的广泛应用。本文以米糠为原料,分别采用碱法和复合法提取米糠蛋白,在提取米糠蛋白的过程中分别加入各种不同的抑制剂,以抑制褐变反应。碱法提取米糠蛋白过程中,最佳抑制剂为1.5%的次氯酸钠,色素抑制率为64.2%,蛋白提取率为53.7%;复合法中,以3.0%的抗坏血酸、1.0%的次氯酸钠和0.15%的L-半胱氨酸为最佳复配抑制剂的情况下,提取出的米糠蛋白颜色浅,此时色素抑制率为69.87%,蛋白提取率为80.06%,褐变抑制效果显著,蛋白提取率高。     

米糠浓缩蛋白的提取及功能性评价

对米糠蛋白的碱法提取新工艺进行了研究并获得最佳工艺条件。试验结果表明 :采用该工艺不仅蛋白提取率达 93 7% ,而且所得米糠浓缩蛋白的白度较通常碱法工艺提高 1倍 ,其功能特性接近美国宝利来大豆分离蛋白。     

米糠浓缩蛋白的提取及功能性评价

对米糠蛋白的碱法提取新工艺进行研究 ,获得最佳工艺条件。试验结果表明 :采用该工艺不仅蛋白提取率达 93 7% ,而且所得米糠浓缩蛋白的白度较通常碱法工艺提高 1倍 ,其功能特性接近美国宝利来大豆分离蛋白     

Precipitation of rice bran protein using carrageenan and alginate

Precipitation of rice bran protein, a high-quality nutritional protein, using polysaccharides (alginate and carrageenan) was investigated at various pH, temperature and amount of polysaccharide with the objective of obtaining higher protein recovery and possible wider industrial application. Both alginate and carrageenan were found to be effective in precipitating rice bran protein. At pH 3.5, the maximum amount of protein precipitated were 95% for a carrageenan-to-protein ratio of 2:1, and 93% for an alginate-to-protein ratio of 1:1. However, change of temperature (20-55 °C) did not have a significant effect (p > 0.05) on the amount of protein precipitated. The precipitate formed using alginate and carrageenan had protein content of 42.15 and 26.48 g/100 g of precipitate, respectively. The freeze dried product obtained from the rice bran extract precipitated with polysaccharides was capable of forming foam and emulsion, indicating its possible utilization as a food ingredient.     

酶法提取脱脂米糠中蛋白质的研究

研究采用复合糖酶处理脱脂米糠后,降低了米糠中半纤维素和植酸盐含量,使蛋白质的提取率和纯度明显提高,米糠蛋白产品的蛋白含量达到80.2%,总糖含量仅为3.7%。聚丙烯酰胺电泳(SDS-PAGE)和高效凝胶过滤色谱(HPSEC)图谱表明,米糠蛋白分子量呈连续分布;HPSEC图谱表明,米糠蛋白的分子以聚集体形式存在。     

Optimization of Rice Bran Fermentation Conditions Enhanced by Baker’s Yeast for Extraction of Protein Concentrate

The rice bran fermentation conditions for extraction of protein concentrate was enhanced by the use of baker’s yeast at optimized conditions using response surface methodology (RSM). A central composite design with three independent variables: fermentation temperature (25 to 35°C), yeast concentration (1 to 5%) and fermentation time (10 to 24 h) was used to study the response variable (protein yield). Results indicated that the generated regression model represented the relationship between the independent variables and the responses. Also, all linear terms, two quadratic terms (fermentation temperature and time) and all interactive terms had significant (p < 0.05) effect on the protein yield. The optimum conditions for yeast pretreatment of rice bran protein extraction were achieved at 30°C for 17 h using 3% yeast concentration to obtain a protein yield of 23.37%, which showed no significant difference (p > 0.05) from the response surface methodology predicted protein yield (23.02%). The use of baker’s yeast in the fermentation of rice bran for extraction of protein concentrate can be more effectively used to improve the extraction yield compared to natural fermented (15.43%) and untreated rice bran (10.16%).     

Chemical,antioxidant, functional and thermal properties of rice bran proteins after yeast and natural fermentations

The paper focuses on the chemical, antioxidant, functional and thermal properties of rice bran proteins after yeast, natural fermentations and unfermented rice bran. Protein content of yeast‐fermented rice bran protein concentrate (YFRBPC), naturally fermented rice bran protein concentrate (NFRBPC) and unfermented rice protein concentrate (UFRBPC) were 72.50%, 68.92% and 65.73%, respectively, while ash content were 4.72%, 4.61% and 3.04%, respectively. The total amino acids of YFRBPC, NFRBPC and UFRBPC were 123.16, 118.45 and 99.39, respectively. DPPH radical inhibition of YFRBPC, NFRBPC and UFRBPC were 58.62%, 55.29% and 47.14%, respectively, while ferric reducing ability power were 0.73, 0.58 and 0.41 mmol TE per gram, respectively. The highest foam capacity of UFRBPC (57.56%), NFRBPC (64.15%) and YFRBPC (76.00%) was observed at pH 9.0. YFRBPC and NFRBPC were lighter in colour than UFRBPC. YFRBPC had higher denaturation temperature and enthalpy value than NFRBPC and UFRBPC. The β‐sheets structures were more in YFRBPC and NFRBPC than UNFBPC.     

反胶束法萃取玉米胚芽蛋白及其功能性研究

研究了AOT/异辛烷反胶束法萃取玉米胚芽蛋白及玉米胚芽蛋白的加工功能性。在实验中分别考察了纤维素酶加酶量、AOT浓度、KCl浓度、缓冲液pH值、W0对玉米胚芽蛋白前萃率的影响,以及萃取时间、KCl浓度、缓冲液pH值对后萃率的影响,确定了前萃的最佳技术条件:加酶量为4 000 IU/g玉米胚芽、AOT浓度为3 g/50 mL异辛烷、萃取pH 6、KCl浓度0.1 mol/L、W0为25;后萃的最佳技术条件为:KCl浓度为0.5 mol/L、萃取pH 10.5,萃取时间40 min;对玉米胚芽蛋白的部分加工功能性进行研究,结果表明其吸油性(2.9 mL/g)、乳化性(54.5%)、乳化稳定性(86.5%)以及泡沫稳定性(58.3%)都较好,但吸水性和起泡性相对较差,玉米胚芽蛋白不但营养效价高,而且具有较好的加工功能特性,在食品工业中具有应用潜力。     

米糠蛋白提取工艺条件的优化

以米糠为原料,分别采用碱法和酶法对米糠蛋白进行提取。在提取过程中,以蛋白提取率为指标,确定料液比、酶用量、时间和温度对米糠蛋白提取率的影响,通过正交试验确定最佳提取工艺。结果表明：碱法最佳提取工艺为料液比1:10(g/mL)、提取时间2.5h、提取温度45℃,米糠蛋白提取率可达57.8%。酶法最佳提取工艺为酶用量2%(E/S)、酶解时间2.5h、酶解温度50℃,米糠蛋白提取率可达38.4%。     

米糠蛋白提取方法研究进展

我国米糠资源丰富,其蛋白质含量较高;该文论述提取米糠蛋白作用机理及方法。     

超声波辅助提取人参淀粉工艺优化及其性质

采用超声波辅助提取人参淀粉,通过单因素和正交试验研究超声波功率、超声波时间、料液比及原料粒度对人参淀粉提取率的影响,确定最佳提取工艺条件。采用扫描电子显微镜、偏光显微镜、红外光谱仪、布拉班德黏度仪、质构仪等对人参淀粉的颗粒性质及理化性质进行研究。结果表明：超声波辅助提取人参淀粉的最佳工艺条件为超声波功率600 W、超声波时间20 min、料液比1∶25（g/mL）、粒度80 目,此时淀粉的提取率高达70.51%,比常规法增加10.69%。在最佳工艺条件下,超声波辅助提取的人参淀粉直链淀粉含量增加,淀粉糊的溶解度、膨胀度及透明度提高,凝沉性减弱。超声波辅助提取的人参淀粉的糊化温度为70.5 ℃,峰值黏度为70.0 BU。     

干热处理对米糠蛋白结构与功能特性的影响

对干热处理后米糠蛋白的结构及功能特性变化进行探讨,结果表明：90 ℃干热处理下米糠蛋白组分发生明显的热变性,米糠蛋白的β-折叠结构含量有较大程度降低,并主要转变为无规卷曲结构和β-转角结构。随着干热处理温度的升高,α-螺旋结构含量逐渐增大,无规卷曲结构和β-转角结构含量并未表现出明显的线性变化趋势。干热处理条件下无序结构的增多促进了米糠蛋白的水合作用,使米糠蛋白溶解性增加,而随着干热处理温度升高至100 ℃,米糠蛋白的溶解度有所降低;无序结构增多使米糠蛋白整体柔性增强,随着干热处理温度的升高,米糠蛋白的乳化性呈现先减小后增大的变化趋势,在100 ℃干热处理下米糠蛋白乳化性达到最大值45.56 m2/g,而米糠蛋白的乳化稳定性亦有所增加;米糠蛋白起泡性随干热处理温度的升高呈现先增大后减小的变化趋势,干热处理温度80 ℃时米糠蛋白起泡性达到最大值为87.36%,米糠蛋白的泡沫稳定性随干热处理温度升高逐渐降低。     

酶法提取大米蛋白研究进展

大米蛋白是一种优质的植物蛋白,因其原料丰富和蛋白的独特功效,具有广阔的市场前景.国外已有此方面产品上市,但国内因尚未得到广泛重视及提取方法不成熟,目前并未得到有效开发应用.本文从酶法角度综述了从米粉、米渣和米糠中提取大米蛋白的研究进展和工艺流程,以提高大米蛋白提取率,满足人们需求;同时指出,由于大米蛋白中80%为水不溶的谷蛋白,应在提高蛋白得率的同时提高其溶解度,扩大应用范围.     

超声波对脱色葵花籽蛋白色泽和功能特性的影响

本实验研究了超声波(200、400、600 W,30 min)技术对脱色的葵花籽蛋白色泽和功能特性的影响.结果表明,与未处理的葵花籽粕蛋白相比,经超声波处理后脱色葵花籽蛋白的溶解度、持水性、乳化性、起泡性和持油性均显著改善(P＜0.05).其中超声功率为400 W时葵花籽蛋白的亮度值(L*)由55.7提高至77.3;超...     

Functional properties of protein hydrolysates from Riceberry rice bran

Protein hydrolysate from pigmented Riceberry rice bran has great potential to be used in food products due to its protein content and antioxidative activities. In this study, characteristics, solubility, heat stability and emulsification properties of protein hydrolysates from the bran fraction of two rice cultivars, commercial rice bran (CBH) and Riceberry bran (RBH), were investigated. Both CBH and RBH showed the lowest solubility near their isoelectric point between pH 2 and 3. Solubility of RBH increased with increasing pH as the hydrolysates became more negatively charged; however, solubility of CBH was less dependent on pH. Heating did not significantly affect solubility of both hydrolysates which could be due to reduced aggregation of low‐molecular weight peptides and/or the exposure of charged and polar groups after hydrolysis. Oil‐in‐water emulsions stabilised by RBH were more stable compared to those stabilised by CBH. Maximum stability was achieved with RBH at pH 6 where no creaming was observed after 14 day storage. Higher stability could be due to increased surface protein coverage, more negative charge and higher viscosity of RBH‐stabilised emulsions. In addition, higher carbohydrate content and the presence of flavonoid could also contribute to an increase in stability. These results can be applied in food products using rice bran protein hydrolysate as nutritional ingredients.