刺参低聚肽的质量评价和抗疲劳作用研究

研究p H渐变条件下采用碱性蛋白酶和菠萝蛋白酶分步酶解猪皮得到的不同分子量胶原蛋白肽的体内外抗氧化活性。猪皮预处理后,采用碱性蛋白酶和菠萝蛋白酶分步进行酶解,酶解液经超滤得到M1 k Da、1 kDaM3 kDa、M3 kDa 3个不同分子量肽段,以福林酚比色法测定各组分肽含量,通过测定各组分肽段对DPPH自由基、ABTS+自由基、O2-自由基及OH自由基的清除实验评价各组分肽的体外抗氧化活性,再以不同分子量肽段酶解液对小鼠进行灌胃,以试剂盒测定小鼠灌胃后血清的总超氧化物歧化酶、谷胱甘肽过氧化物酶、过氧化氢酶的活性、总抗氧化能力和微量丙二醛含量评价各组分肽的体内抗氧化活性。综合体内外抗氧化实验数据,各组分肽的抗氧化能力强弱顺序为:小于1 kDa组分1 k Da～3 kDa组分大于3 kDa组分。pH渐变条件下采用碱性蛋白酶和菠萝蛋白酶分步酶解的各组分猪皮胶原蛋白肽在体内外均有不同程度的抗氧化能力,且分子量越小,抗氧化活性越强,可对机体起到保护作用。     

紫苏籽粕蛋白源抗氧化肽的纯化、结构鉴定及体外抗氧化活性

通过单因素和响应面实验对紫苏籽粕蛋白的闪提工艺进行了优化,将所获蛋白通过碱性蛋白酶酶解,酶解物依次通过超滤和柱层析进行分离纯化,并对抗氧化活性最高的多肽进行液质分析。结果表明,紫苏籽粕蛋白提取的最优工艺参数为：料液比1︰20(g/mL)、闪提pH 10、闪提时间30 s和闪提转速3000 rpm。蛋白酶解物经超滤分离后,其分子量小于3kDa的组分具有较高的抗氧化活性、该组分经DEAE-32离子交换色谱分离后, 得到D1、D2、D3共3个组分,其中D1的抗氧化活性最好,D1经Sephadex G-25凝胶层析分离纯化后,富集得到G1和G2两个组分,组分G1抗氧化活性最高。抗氧化肽G1对DPPH、ABTS、O_2^-、.OH 自由基清除率及还原力依次为98.97%、85.11%、91.83%、93.40%、0.477;通过LC-MS-MS鉴定,抗氧化活性肽G1组分主要由15个氨基酸组成,荷质比m/z为672.39,分子质量为1718.82 Da,其氨基酸序列为Glu－Met－Pro－Tur－lle－Ala－Ser－Met－Gly－lle－Tyr－Val－Val－Ser－Lys。     

海参肽的提取分离及其体外抗氧化活性

以水解度为指标,试验研究了复合蛋白酶、木瓜蛋白酶、水产蛋白酶、中性蛋白酶、风味蛋白酶、胰蛋白酶和碱性蛋白酶对海参蛋白的水解能力,确定以复合蛋白酶为最佳用酶。以料液比、加酶量、酶解时间为试验因素,水解度为响应值,通过响应面法对提取工艺进行优化,结果表明该酶最佳酶解条件为:加酶量0.79%、料液比1︰5.35 (g/mL)、酶解时间3.93 h。在此条件下,海参蛋白水解度为21.38%。分别用截留分子量3 kDa和1 kDa超滤膜对海参肽进行分级分离,得到分子量大于3 kDa, 1～3 kDa和小于1 kDa 3种海参肽,将不同分子量海参肽分别在ABTS+·清除活性、还原力、DPPH·清除活性、O_2~-·清除活性4种体系下比较三者体外抗氧化能力。结果显示:分子量小于1 kDa海参肽对ABTS+·、O_2~-·清除活性最强, 1～3 kDa海参肽次之,大于3 kDa海参肽最弱;分子量大于3 kDa海参肽还原力以及对DPPH清除活性最强。     

豌豆ACE抑制肽对诱导损伤的EA.hy.926细胞的保护作用

目的：实现豌豆蛋白的高值化利用。方法：以豌豆蛋白为原料,采用双酶协同酶解法制备豌豆蛋白源ACE抑制肽,以酶解时间和酶添加顺序为变量,以ACE抑制率、水解度、可溶蛋白含量为指标确定豌豆ACE抑制肽的最佳酶解工艺。将最佳酶解工艺条件下制得的ACE抑制肽进行超滤分级,探究分子量对ACE抑制活性的影响,最后通过测定ET-1、MDA含量、SOD和NO含量水平验证ACE抑制活性较高的豌豆肽对诱导损伤的EA.hy.926细胞的保护作用。结果：双酶法制备豌豆ACE抑制肽的最佳工艺条件为底物质量浓度100 mg/mL, 3.0%的碱性蛋白酶在pH 9.5、50 ℃条件下酶解2.0 h后加入3.0%的复合蛋白酶,在pH 7.0、50 ℃条件下继续酶解2.0 h。此条件下的豌豆蛋白水解物 ACE抑制率的IC₅₀值为1.141 mg/mL;小于2.5 kDa的肽组分其ACE抑制活性最强,且能显著减少Ang-Ⅱ诱导损伤细胞的ET-1、MDA含量,增加SOD和NO含量水平。结论：豌豆ACE抑制肽对Ang-Ⅱ诱导损伤EA.hy.926细胞具有保护作用。     

麦芽协同蛋白酶酶解豌豆蛋白产物的功能特性及抗氧化活性

采用麦芽粉分别与风味蛋白酶、中性蛋白酶和木瓜蛋白酶协同酶解豌豆蛋白,得到3种酶解物（MFH、MNH和MPH）,研究酶解物的功能特性及抗氧化活性。结果表明：与豌豆蛋白相比,酶解物的溶解性、持油性和体外消化性较高;酶解后豌豆蛋白的抗氧化活性显著提高（P<0.05）,MFH、MNH和MPH的DPPH·清除能力IC50值分别为5.64、7.22、8.95 mg/mL（以蛋白质质量浓度计）,·OH清除能力IC50值分别为1.45、2.19、2.04 mg/mL（以蛋白质质量浓度计）;与仅用蛋白酶酶解得到的酶解物相比,MNH的苦味减轻。     

藜麦糠抗氧化肽的超滤分离及其体外抗氧化活性

为了大批量生产抗氧化活性最好的藜麦糠抗氧化肽,采用风味酶与碱性蛋白酶组合对藜麦糠蛋白进行酶解,制备酶解液。利用超滤技术分离纯化藜麦糠抗氧化肽,并评价分离得到的不同分子质量段抗氧化肽的体外抗氧化活性,优选出抗氧化活性最好的抗氧化肽。以膜通量为指标,压力、时间和滤液质量分数为3个工艺参数,通过单因素和正交实验,探究超滤分离截留分子量为10 ku的藜麦糠抗氧化肽的最佳工艺条件。结果表明,不同分子量段的超滤组分具有不同的抗氧化活性,其中分子量为5~10 ku的抗氧化肽较其他分子量范围的超滤组分的抗氧化活性最好。藜麦糠抗氧化肽的最佳超滤条件为压力0.16 MPa,时间20 min,滤液质量分数2%,在此条件下得到膜通量为(41.22±0.50) L/m2·h。由此可实现5~10 ku的抗氧化肽的大量生产。     

卵白蛋白肽复合酶法制备工艺优化及解酒效果

目的:验证卵白蛋白肽的解酒活性,提高鸡蛋产品的附加值。方法:用碱性蛋白酶和胰蛋白酶复合酶解卵白蛋白,以乙醇脱氢酶(ADH)激活率为指标,采用响应曲面法优化酶解工艺。通过检测卵白蛋白肽的总抗氧化性、水解度、氨基酸组成及相对分子质量,评估卵白蛋白肽的解酒效果。结果:最佳酶解工艺条件:酶解时间5 h,复合酶用量3 100 U/g,酶解温度50 ℃,料液比(m_卵白蛋白∶V_蒸馏水)3.5∶25 (g/mL),在此条件下得到的卵白蛋白肽ADH激活率为(22.71±0.15)%,总抗氧化能力值为(9.51±0.03) U/mL,水解度为(29.28±0.16)%。卵白蛋白肽富含谷氨酸(9.554 3%)、丙氨酸(3.863 3%)、亮氨酸(5.764 7%)等有益于提高解酒活性的氨基酸,小分子肽(＜1 000 Da)含量超过88.77%。结论:使用复合酶解法制备的卵白蛋白肽具有良好的抗氧化活性和解酒效果。     

大口黑鲈鱼皮胶原蛋白肽的制备及抗氧化活性研究

目的：探究酶种类对胶原蛋白肽抗氧化活性的影响。方法：从大口黑鲈(Micropterus salmoides)鱼皮中提取胶原蛋白,采用碱性蛋白酶、中性蛋白酶、木瓜蛋白酶和胰蛋白酶酶解胶原蛋白,得到碱性蛋白酶酶解胶原蛋白肽(APP)、中性蛋白酶酶解胶原蛋白肽(NPP)、木瓜蛋白酶酶解胶原蛋白肽(PP)、胰蛋白酶酶解胶原蛋白肽(TP),比较其总抗氧化活性、还原活性、对DPPH·、·OH 和O-2·清除能力以及亚铁离子螯合能力和脂质氧化抑制活性。结果：4种蛋白酶酶解胶原蛋白肽都具有抗氧化活性,且抗氧化能力与胶原蛋白肽浓度呈正相关,其中APP的抗氧化活性最佳,总抗氧化活性和还原活性分别为1.725和0.958,对DPPH·和O-2·清除率分别为56.35%和38.41%。结论：碱性蛋白酶酶解的胶原蛋白肽抗氧化活性更佳。     

紫苏粕蛋白抗氧化活性肽的制备、分离纯化及序列鉴定

以紫苏粕粉为原料，使用碱性蛋白酶进行水解反应，制备抗氧化活性肽。采用超滤离心、凝胶过滤色谱和反相色谱等分离纯化手段对其富集。结果表明，相较其它3种蛋白酶，碱性蛋白酶Alcalase对紫苏粕蛋白的水解程度最高，约为(25.94±0.21)%；碱性蛋白酶作用紫苏蛋白后的酶解产物的抗氧化活性最好，对DPPH自由基清除率约为(91.01±0.73)%。酶解上清液经超滤离心分离后最小分子质量组分F1(小于3 ku)抗氧化活性最强，F1组分经Sephadex G-25凝胶过滤色谱分离后按照分子质量大小依次得到P1、P2、P3 3个组分，其中分子质量最小的P3组分抗氧化活性最高。P3组分经反相色谱分离所得4个组分中，最后被洗脱出来的P3-4组分疏水性最强且DPPH·自由基清除率最高，质量浓度为3 μg/mL的 P3-4溶液的DPPH·清除率为(58.8±0.78)%。通过LC-MS-MS 鉴定，抗氧化活性肽P3-4组分为十二肽，其氨基酸序列为Lys-Leu-Lys-Asp-Ser-Phe-Glu-Arg-Gln-Gly-Met-Val，分子质量为 1 437.8 u。本研究结果为深入开发紫苏蛋白资源，研发紫苏抗氧化活性肽提供理论参考。     

酶解核桃蛋白制备抗氧化肽的研究

利用木瓜蛋白酶酶解核桃分离蛋白制备小分子活性肽,并研究了不同分子量段核桃小分子肽的抗氧化性能。通过单因素实验和正交实验,确定了木瓜蛋白酶制备抗氧化肽的最佳酶解条件为:pH8.5,温度50℃,酶与底物浓度之比[E]/[S]=3:100,底物浓度[S]=3.5g/100mL,酶解时间5h。用截留分子量分别为3kDa和10kDa的超滤膜将核桃粗肽液分离成<3kDa、3～10kDa及>10kDa3个分子量段,并对不同分子量段核桃多肽的抗氧化性进行了研究,结果表明,分子量<3kDa的核桃多肽的抗氧化性大于其他两个分子量段。     

大豆蛋白溶解性研究

该文概述大豆蛋白溶解特性及其与一般物质溶解差异,介绍提高大豆蛋白溶解性改性方法及研究现状,对比不同改性增溶方法优、缺点,并提出今后大豆蛋白改性研究方向。     

Short communication: Muscle protein synthetic response to microparticulated whey protein in middle-aged men

Whey protein concentrate (WPC) is a high-quality dairy ingredient that is often included in formulated food products designed to stimulate muscle anabolism. Whey protein concentrate can be affected by UHT processing, and its sensory properties are not compatible with some formulated food products. Microparticulated WPC (mWPC) is a novel ingredient that is resistant to heat treatment and has enhanced sensory properties. When 16 healthy middle-aged men consumed 20 g of either WPC or mWPC, both proteins increased plasma essential AA and leucine concentrations with no detectable difference in curve kinetics. Myofibrillar protein synthesis was increased in both groups for 90 min after ingestion with no difference between groups. Ingestion of mWPC resulted in a muscle anabolic response that was equivalent to that of WPC over the full 210-min measurement period. Formulated products incorporating mWPC or standard WPC would provoke equivalent anabolic responses.     

Co-precipitation of whey and pea protein – indication of interactions

The aim was to optimise the yield of co-precipitation of whey protein isolate (WPI) and pea protein isolate (PPI) and compare co-precipitates and protein blends with respect to solubility. The yield of co-precipitates was tested with different protein ratios of WPI and PPI in combination with different temperatures and acid precipitation (pH 4.6). The highest precipitation yield was obtained at protein ratios WPI < PPI, high temperature and alkaline protein solvation. The solubility was measured by an instability index and absorption spectroscopy of re-suspended precipitated proteins at pH 3, 7 and 11.5. Co-precipitates had significantly lower solubility than protein blends. Protein ratios WPI > PPI, low precipitation temperature and high pH showed the highest solubility. Differences in protein composition between co-precipitates and protein blends were observed with SDS-PAGE and matrix-assisted laser desorption ionisation time-of-flight, and indicated different protein–protein interaction in samples, which needs further investigations.     

细菌中蛋白质样品制备方法研究进展

细菌在生长繁殖时,细菌蛋白的表达受到环境影响而存在较大差异,使得细菌蛋白表达具有复杂性。在食品生产加工过程中可能会受到致病菌污染,细菌产生的内毒素和外毒素均会对人体健康构成威胁,因此需要高灵敏度和高特异性的检测方法来定量分析和鉴定食品中的细菌毒素。蛋白组学方法可以揭示细菌蛋白组成及其潜在的生物学功能,感染过程中菌体蛋白表达变化和致病机制理。其中,细菌蛋白样品的前处理作为细菌蛋白组学研究的关键步骤,直接影响鉴定的细菌蛋白质量。本文主要阐述目前细菌蛋白组学研究中菌体蛋白和胞外蛋白样品制备方法及其对蛋白鉴定和定量的影响,将为更深入的开展细菌蛋白组学研究提供参考。     

几种新型花生蛋白产品的生产

本文从花生蛋白质利用的角度介绍了几种新型花生蛋白产品的加工工艺，针对我国人民膳食结构中蛋白质的摄入水平较低的实际情况，论述了花生蛋白开发利用的必要性，展望了花生蛋白开发利用的广阔前景。     

Physicochemical and Functional Properties of Soy Protein Substrates Modified by Low Levels of Protease Hydrolysis

ABSTRACT: Endo-protease treatments achieving low degrees of hydrolysis (DH 2% and 4%) were used to improve functional properties of hexane-extracted soy flour (HESF), extruded-expelled partially defatted soy flour (EESF), ethanol-washed soy protein concentrate (SPC), and soy protein isolate (SPI). These substrates had protein dispersibility indices ranging from 11% to 89%. Functional properties, including solubility profile (pH 3 to 7), emul-sification capacity and stability, foaming capacity and stability, and apparent viscosity were determined and related to surface hydrophobicity and peptide profiles of the hydrolysates. Protein solubilities of all substrates increased as DH increased. Emulsification capacity and hydrophobicity values of the enzyme-modified HESF and EESF decreased after hydrolysis, whereas these values increased for SPC and SPI. Emulsion stability was improved for all 4% DH hydrolysates. Hydrolyzed SPC had lower foaming capacity and stability. For substrates other than SPC, foaming properties were different depending on DH. Hydrolysis significantly decreased the apparent viscosities regardless of substrate. Sodium dodecyl sulfate-polyacrylamide gel electrophoresis (SDS-PAGE) indicated differences in the molecular weight profiles of the hydrolysates. HESF and EESF, which had high proportions of native-state proteins, showed minor changes in the peptide profile due to hydrolysis compared with SPC and SPI.     

大豆分离蛋白改性对其功能性质影响

大豆分离蛋白是大豆蛋白最为精制形式,广泛应用于食品工业,并在不同产品中表现出不同功能。该文综述近年来大豆分离蛋白物理、化学、酶法及基因工程改性对其功能性质影响,经不同方式改性可产生合适功能性质,从而拓宽大豆分离蛋白在食品工业中应用。     

中国植物油料蛋白生产现状与发展趋势

对中国主要植物油料蛋白--大豆蛋白、花生蛋白、棉籽蛋白、菜籽蛋白工业的生产现状与发展趋势进行了论述,同时对这4种蛋白的氨基酸组成、营养效价和生物价进行了比较.结果表明,菜籽蛋白的生物价和营养效价最高,其次为大豆蛋白,再次为棉籽蛋白,最后为花生蛋白.目前我国对大豆蛋白开发利用最多,而对于菜籽蛋白和棉籽蛋白,由于脱毒技术等原因,开发利用不足.随着人民生活水平的提高、技术的成熟,这些油料蛋白将得到进一步的开发、利用,市场潜力巨大.     

Formulation,process conditions,and biological evaluation of dairy mixed gels containing fava bean and milk proteins: Effect on protein retention in growing young rats

Food formulation and process conditions can indirectly influence AA digestibility and bioavailability. Here we investigated the effects of formulation and process conditions used in the manufacture of novel blended dairy gels (called “mixed gels” here) containing fava bean (Vicia faba) globular proteins on both protein composition and metabolism when given to young rats. Three mixed dairy gels containing casein micelles and fava bean proteins were produced either by chemical acidification (A) with glucono-δ-lactone (GDL) or by lactic acid fermentation. Fermented gels containing casein and fava bean proteins were produced without (F) or with (FW) whey proteins. The AA composition of mixed gels was evaluated. The electrophoretic patterns of mixed protein gels analyzed by densitometry evidenced heat denaturation and aggregation via disulfide bonds of fava bean 11S legumin that could aggregate upon heating of the mixtures before gelation. Moreover, fermented gels showed no particular protein proteolysis compared with gel obtained by GDL-induced acidification. Kinetics of acidification were also evaluated. The pH decreased rapidly during gelation of GDL-induced acid gel compared with fermented gel. Freeze-dried F, A, and FW mixed gels were then fed to 30 young (1 mo old) male Wistar rats for 21 d (n = 10/diet). Fermented mixed gels significantly increased protein efficiency ratio (+58%) and lean mass (+26%), particularly muscle mass (+9%), and muscle protein content (+15%) compared with GDL-induced acid gel. Furthermore, F and FW formulas led to significantly higher apparent digestibility and true digestibility (+7%) than A formula. Blending fava bean, casein, and whey proteins in the fermented gel FW resulted in 10% higher leucine content and significantly higher protein retention in young rats (+7% and +28%) than the F and A mixed gels, respectively. Based on protein gain in young rats, the fermented fava bean, casein, and whey mixed proteins gel was the most promising candidate for further development of mixed protein gels with enhanced nutritional benefits.