响应面法优化磷酸化改性花生分离蛋白－多肽膜的制备工艺

    为了优化磷酸化改性花生分离蛋白-多肽膜制备工艺条件，在单因素基础上，通过响应面Box-Benhnken进行实验设计。结果表明，最优工艺参数：蛋白浓度8%、pH值8.2、甘油百分含量（占蛋白）13.4%、黄原胶百分含量（占蛋白）1%、时间60min、温度69℃、超声波功率270W、超声波频率28kHz、多肽溶液的浓度61mg/mL；此工艺条件下，膜厚度、吸水率和透光率理论预测值分别为86μm、41.9%和53.6%，验证实验值分别为88±2μm、43.1±1.2%和52.4±1.5%，两者的差值分别为2.33%、2.86%和2.24%，说明响应面二次模型的拟合良好；磷酸化改性花生分离蛋白-多肽膜的抗拉强度9.62MPa、断裂延伸率101.68%、溶解性47.69%、水蒸气透过率6.95 g•m-2· h-1等功能性质和DPPH自由基清除活性IC50值7.70 mg·mL-1、羟自由基清除活性IC50值5.98 mg·mL-1、超氧阴离子自由基清除活性IC50值4.20 mg·mL-1、铁离子螯合力活性IC50值3.79 mg·mL-1、铜离子螯合力活性IC50值13.61 mg·mL-1、脂质过氧化抑制活性IC50值8.62 mg·mL-1、铁还原力IC50值13.93mg·mL-1、钼还原力IC50值5.49mg·mL-1等抗氧化活性较磷酸化改性花生分离蛋白膜有所改善。本研究结果为磷酸化改性花生分离蛋白在蛋白膜方面的应用提供一种新途径。     

Antioxidant Activities of Peanut Protein Separated by Ultrafiitration

用碱性蛋白酶解法制备花生多肽,将得到的花生肽酶解液通过超滤的方法进行分离得到不同分子量段的多肽,对其进行抗氧化活性的研究得到抗氧化活性最强的分子量段的多肽。将花生短肽酶解液稀释并分别通过5KD、3KD的卷式纤维膜进行超滤得到三个分子量段的花生短肽。比较各分子量段的多肽对二苯代苦味酰基（DPPH）自由基的清除率、抗亚油酸氧化能力、羟自由基的清除率及还原力。结果表明：花生肽具有一定的抗氧化能力,且3KD以下的多肽抗氧化能力最强,3-5KD分子量段的多肽次之,大于5KD分子量的多肽表现出较弱的抗氧化能力。     

超滤法分离花生肽及其抗氧化活性的研究

用碱性蛋白酶解法制备花生多肽,将得到的花生肽酶解液通过超滤的方法进行分离得到不同分子量段的多肽,对其进行抗氧化活性的研究得到抗氧化活性最强的分子量段的多肽。将花生短肽酶解液稀释并分别通过5KD、3KD的卷式纤维膜进行超滤得到三个分子量段的花生短肽。比较各分子量段的多肽对二苯代苦味酰基（DPPH）自由基的清除率、抗亚油酸氧化能力、羟自由基的清除率及还原力。结果表明：花生肽具有一定的抗氧化能力,且3KD以下的多肽抗氧化能力最强,3-5KD分子量段的多肽次之,大于5KD分子量的多肽表现出较弱的抗氧化能力。     

花生非淀粉多糖和抗氧化肽同步提取技术研究

研究米曲霉和酿酒酵母混合固态发酵热榨花生粕同步提取花生非淀粉多糖和抗氧化肽,为花生粕的高值化利用提供理论基础。以发酵产物的可溶性氮浓度、1,1-二苯基苦基苯肼(DPPH)自由基清除率、羟自由基清除率和非淀粉多糖得率为考察指标,研究了菌种比例、接种量、营养盐溶液量、发酵温度、发酵时间、水浴温度和水浴时间对发酵效果的影响,确定最佳工艺条件为:菌种比例1∶2,接种量3mL,营养盐溶液添加量30mL,发酵温度33℃,发酵时间42h,水浴温度40℃,水浴时间6h。此工艺下发酵产物的可溶性氮浓度为46.32mg/mL、DPPH自由基清除率为71.90%、羟自由基清除率为96.96%、非淀粉多糖得率为4.36%。发酵产物经乙醇沉淀和超滤分离得到的花生非淀粉多糖和抗氧化肽产品具有清除自由基、抑制脂质过氧化、金属离子螯合力和还原力等4大类抗氧化活性。     

番荔枝种子粗多糖抗氧化能力研究

为了探讨番荔枝种子多糖的抗氧化能力,将晒干的种子经粉碎匀浆、乙醇回流、减压浓缩、氯仿萃取和甲醇石油醚抽提后得到粗提物,经干燥后配制成不同浓度的溶液,分别以相同浓度的维生素C作对照,测定了番荔枝种子多糖还原力、抗脂质过氧化能力以及清除DPPH·自由基、超氧阴离子自由基(O·-2)和羟基自由基(·OH)的能力。研究结果表明:番荔枝种子多糖具有较强的还原力,对脂质过氧化有良好的抑制作用,同时具有较强的清除DPPH·、O·-2和·OH的能力,说明番荔枝种子多糖具有较强的抗氧化能力,抗氧化性随浓度增大而增强,但其抗氧化能力弱于维生素C。     

响应面法优化限制性酶解花生浓缩蛋白制备工艺研究

研究超声波辅助蛋白酶制备限制性酶解花生浓缩蛋白,为扩大花生浓缩蛋白的应用提供理论基础。以限制性酶解花生浓缩蛋白的溶解度和持水性为考察指标,研究了底物浓度、pH值、加酶量、超声波频率、超声波功率、温度和时间对溶解度和持水性的影响,确定最佳工艺条件为:底物浓度8.1%、pH值9.0、加酶量12.5μL/g、超声波频率45kHz、超声波功率150w、温度51℃和时间21min。此工艺下溶解度和持水性理论值分别为77.63%和9.77mL/g。验证试验得到的平均溶解度和持水性分别为78.89±0.53%和9.58±0.26mL/g,与理论值分别相差1.62%和1.94%,说明模型与实际情况拟合较好,验证了预测模型的正确性。限制性酶解花生浓缩蛋白具有较好的功能特性和清除自由基、还原力、金属离子螯合力、抑制脂质过氧化等4大类抗氧化活性。     

鹅掌柴提取物的抗氧化活性

从清除超氧阴离子自由基(O-2)、还原力、清除DPPH自由基、清除羟基自由基(·OH)等方面,研究鹅掌柴提取物的抗氧化活性.结果表明:鹅掌柴提取物对DPPH自由基和羟基自由基的清除能力较强,清除率分别为78.57%和74.99%,对脂质体过氧化的的抑制率为21.41%;与VE、VC、BHT相比,鹅掌柴提取物的还原能力和对Fe2+的络合能力也较强;但对超氧阴离子自由基的清除能力较弱.因此.鹅掌柴提取物是一种抗氧化功效较强的活性物质,具有很好的保健功能.     

“文椰2号”椰子外果皮中50％乙醇提取物体外清除自由基能力的研究

从清除超氧阴离子自由基、还原力、清除DPPH自由基、清除羟基自由基等方面,研究“文椰2号”椰子外果皮中50％乙醇提取物的抗氧化性。结果表明,“文椰2号”椰子外果皮中50％乙醇提取物的还原能力较强,对DPPH·自由基和羟基自由基有较强的清除能力,对Fe2+的络合能力和脂质体过氧化反应的抑制作用也较强,但对超氧阴离子自由基的清除能力较弱。因此,椰子外果皮中50％乙醇提取物是一种抗氧化功效较强的活性物质,具有很好的保健功能。     

Radical Scavenging Activity of the Extraction with 50％ Ethanol from Epicarp of WenYe Ⅱ Coconut

从清除超氧阴离子自由基、还原力、清除DPPH自由基、清除羟基自由基等方面,研究“文椰2号”椰子外果皮中50％乙醇提取物的抗氧化性.结果表明,“文椰2号”椰子外果皮中50％乙醇提取物的还原能力较强,对DPPH.自由基和羟基自由基有较强的清除能力,对Fe2+的络合能力和脂质体过氧化反应的抑制作用也较强,但对超氧阴离子自由基的清除能力较弱.因此,椰子外果皮中50％乙醇提取物是一种抗氧化功效较强的活性物质,具有很好的保健功能.     

野葛愈伤组织提取物体外清除自由基活性的研究

为确定野葛愈伤组织提取物的清除自由基和抗氧化活性及开发新型天然抗氧化剂提供试验依据,采用1,1-二苯基苦基苯肼(DPPH.)的有机自由基体系以及羟自由基和超氧阴离子自由基两种无机活性氧自由基体系,检测野葛愈伤组织提取物的体外清除自由基和抗氧化活性,并与野葛根提取物、葛根素、Vc和茶多酚进行对比研究。结果表明:野葛愈伤组织提取物对DPPH.自由基的清除能力较强,与野葛根提取物、茶多酚的清除能力相当,且显著优于葛根素和Vc;野葛根提取物的羟自由基(.OH)清除活性最高,茶多酚和野葛愈伤异黄酮次之,Vc对.OH的清除活性稍弱;野葛愈伤组织提取物的羟自由基清除活性随处理浓度增加而提高;野葛愈伤组织提取物、野葛根提取物和Vc均具有较强的清除O-2.能力,均显著高于葛根素和茶多酚。说明野葛愈伤组织提取物具有较强的清除自由基和抗氧化活性。     

Reverse-phase HPLC Separation of Hemp Seed (Cannabis sativa L.) Protein Hydrolysate Produced Peptide Fractions with Enhanced Antioxidant Capacity

Hemp seed protein hydrolysate (HPH) was produced through simulated gastrointestinal tract (GIT) digestion of hemp seed protein isolate followed by partial purification and separation into eight peptide fractions by reverse-phase (RP)-HPLC. The peptide fractions exhibited higher oxygen radical absorbance capacity as well as scavenging of 2,2-diphenyl-1-picrylhydrazyl, superoxide and hydroxyl radicals when compared to HPH. Radical scavenging activities of the fractionated peptides increased as content of hydrophobic amino acids or elution time was increased, with the exception of hydroxyl radical scavenging that showed decreased trend. Glutathione (GSH), HPH and the RP-HPLC peptide fractions possessed low ferric ion reducing ability but all had strong (>60 %) metal chelating activities. Inhibition of linoleic acid oxidation by some of the HPH peptide fractions was higher at 1 mg/ml when compared to that observed at 0.1 mg/ml peptide concentration. Peptide separation resulted in higher concentration of some hydrophobic amino acids (especially proline, leucine and isoleucine) in the fractions (mainly F5 and F8) when compared to HPH. The elution time-dependent increased concentrations of the hydrophobic amino acids coupled with decreased levels of positively charged amino acids may have been responsible for the significantly higher (p?<?0.05) antioxidant properties observed for some of the peptide fractions when compared to the unfractionated HPH. In conclusion, the antioxidant activity of HPH after simulated GIT digestion is mainly influenced by the amino acid composition of some of its peptides.     

Biofunctionality of Enzymatically Derived Peptides from Codfish (Gadus morhua) Frame: Bulk In Vitro Properties,Quantitative Proteomics,and Bioinformatic Prediction

Protein hydrolysates show great promise as bioactive food and feed ingredients and for valorization of side-streams from e.g., the fish processing industry. We present a novel approach for hydrolysate characterization that utilizes proteomics data for calculation of weighted mean peptide properties (length, molecular weight, and charge) and peptide-level abundance estimation. Using a novel bioinformatic approach for subsequent prediction of biofunctional properties of identified peptides, we are able to provide an unprecedented, in-depth characterization. The study further characterizes bulk emulsifying, foaming, and in vitro antioxidative properties of enzymatic hydrolysates derived from cod frame by application of Alcalase and Neutrase, individually and sequentially, as well as the influence of heat pre-treatment. All hydrolysates displayed comparable or higher emulsifying activity and stability than sodium caseinate. Heat-treatment significantly increased stability but showed a negative effect on the activity and degree of hydrolysis. Lower degrees of hydrolysis resulted in significantly higher chelating activity, while the opposite was observed for radical scavenging activity. Combining peptide abundance with bioinformatic prediction, we identified several peptides that are likely linked to the observed differences in bulk emulsifying properties. The study highlights the prospects of applying proteomics and bioinformatics for hydrolysate characterization and in food protein science.     

Preparation and bioactivity evaluation of low salt peptide from sunf lower seed meal

Sunflower seed meal peptide as one sort of bioactive peptide has intensively application prospects. However, preparation of low salt peptide from sunflower seed meal with high efficiency remains a challenge. In this study, single and compound proteases were optimized to hydrolyze protein. Results showed that hydrolysis at pH 7.0 by proteases resulted in ash content in the range of 5.66%-7.37% and small peptides. Among all hydrolysis processes, sequential hydrolysis of Alcalase with Flavourzyme and Alcalase with Protamex showed higher nitrogen recovery ratio (67.66% and 66.49%, respectively). Furthermore, biological activities of peptides were investigated by testing their ABTS (2,2-azinobis (3-ethylben-zothiazoline-6-sulfonic acid) diammonium salt) radical scavenging activity, DPPH (2,2-diphenyl-1-picrylhydrazil) radical scavenging activity and angiotensin converting enzyme (ACE) inhibitory activity. Peptide hydrolyzed by Alcalase with Papain presented the highest antioxidant activity, followed by Alcalase with Protamex, with ABTS scavenging rate as 63.01% and 31.75%, and DPPH scavenging rate as 56.04% and 28.06%, respectively. Synchronously, peptide hydrolyzed by Alcalase with Protamex and Alcalase with Alcalase had the highest ACE inhibitory activity (56.74%, 56.76%). In conclusion, hydrolysis by proteases Alcalase with Protamex at pH 7.0 was the most effective method for the preparation of low salt peptide from sunflower seed meal, which could be an alternative for anti-oxidants and anti-vasoconstrictor.     

Proximate Composition and Functional Properties of Fullfat and Defatted Beniseed (Sesamum Indicum L.) Flour

The proximate composition and functional properties of fullfat and defatted beniseed (Sesamum indicum L.) flour were evaluated. Functional properties studied were foam capacity and stability, water and oil absorption, bulk density, emulsion capacity and nitrogen solubility. Defatting increased the crude protein, ash, crude fiber, carbohydrate and mineral contents. Defatted flour showed comparatively better foam capacity and stability, water absorption and emulsion capacities but diminished bulk density and oil absorption capacity. Nitrogen solubility was pH dependent with a minimum at pH 4 and maximum at pH 8. Maximum nitrogen solubility (95%) was recorded for defatted flour while that for the fullfat flour was 60%. The proximate composition and functional properties of the samples suggest that beniseed flour would have useful application in fabricated foods.     

pH值和热处理对大豆肽稳定性的影响

分别采用Folin-酚法、SE-HPLC、火焰原子吸收分光光度法研究了pH值和加热处理对大豆肽的稳定性(包括溶解性、分子量分布、可溶性钙结合量)的影响.结果表明:在pH值3～11时对大豆肽的溶解性和分子量分布均无显著影响,pH值9时大豆肽的钙结合能力最大;高温热处理(温度为80℃、100℃)对大豆肽的溶解度无显著影响,但都不同程度的增加了大分子(>20 KDa)的相对含量,100℃时肽的聚合速度更快;80℃加热10 min提高了大豆肽的钙结合能力,热处理温度升高或加热时间延长均会导致钙结合能力的下降.     

乳酸菌固态发酵制备花生蛋白肽及抗氧化活性研究

研究乳酸菌固态发酵制备花生蛋白肽,为进一步研究花生粕专用蛋白基料产品提供理论基础.本研究运用单因素和正交试验方法对固态发酵制备花生蛋白肽工艺条件进行优化,其最佳制备工艺条件为：营养盐溶液添加量25mL,乳酸菌液添加量5mL,25℃下发酵72h.此工艺下制备的花生蛋白肽的可溶性氮浓度达到70.92mg/mL,发酵液对1,1-二苯基苦基苯肼（DPPH）自由基清除率为95.00％,羟自由基清除率为86.28％.花生蛋白肽的抗氧化活性结果显示,对超氧阴离子自由基的清除率是74.19％,对铁离子和铜离子螯合率分别为17.71％和93.28％,对腊质过氧化的抑制率为36.03％,铁还原力和钼还原力吸光值分别为1.103和0.983.     

Improvement of the functionality of vegetable proteins by controlled enzymatic hydrolysis

Vegetable proteins are available to the food industry in various forms, such as flours, concentrates, isolates, and TVP (textured vegetable protein). However, the functional properties of these products are not always optimal and need improvement for certain applications. In recent years it has been demonstrated that a limited enzymatic hydrolysis offers a convenient and specific means of improving certain functional properties of vegetable proteins. The hydrolysis reaction is controlled by the degree of hydrolysis (DH) which is defined as the percentage of peptide bonds cleaved. Under neutral or slightly alkaline conditions, DH can be monitored continuously by the pH-stat technique, since the amount of base necessary to maintain a constant pH is proportional to DH. The reaction is terminated at a preset DH-value to obtain the desired properties of the hydrolysate.Protein products from soya bean, faba bean, and potato were hydrolysed to DH 0%, 3% and 5%, and certain functional properties (iso-electric solubility, emulsification capacity, whipping expansion, and foam stability) were evaluated. The general picture observed is an increase, often pronounced, in these four properties with increasing DH — however, there are also distinct differences between the protein sources as well as between the different forms of a particular protein. This work demonstrates that protein sources indigenous to Europe are fully comparable to soya protein with respect to potential functional uses.