Improving antioxidant activities of whey protein hydrolysates obtained by thermal preheat treatment of pepsin,trypsin, alcalase and flavourzyme

Antioxidant activity of whey protein concentrate (WPC) hydrolysates was evaluated. Hydrolysates were obtained by pepsin, trypsin, alcalase and flavourzyme enzymatic reaction and preheat treatment of 95 °C for 5 or 10 min. The degree of hydrolysis (DH) was determined by 2,4,6‐trinitrobenzene sulphonic acid method, and antioxidant properties were determined by three spectrophotometric methods: ferricyanide method, ferric reducing/antioxidant power assay and diphenyl‐picryl hydrazinyl radical‐scavenging activity. For all the enzymes, briefly preheat treatment (95 °C/5 min) increased DH of WPC. Alcalase hydrolysates showed the highest antioxidant activity by three methods. The changes in antioxidant activity was coincidental with the changes in DH (R² = 0.988). Hydrolysates analysed by polyacrylamide gel electrophoresis and high performance liquid chromatography indicated that the α‐La was hydrolysed completely by pepsin, trypsin and alcalase and was resistant to flavourzyme to some extent; β‐lactoglobulin was only completely hydrolysed by trypsin and alcalase. Results indicated that antioxidant activity of hydrolysates was greatly related to the exposure of amino acid residues.     

山楂原花青素的抗氧化活性研究

研究了山楂果实中的原花青素在溶液体系和脂质体体系中的体外抗氧化活性。在所用的实验模型中,山楂原花青素表现出较强的清除自由基和抑制脂质过氧化的能力。对.OH,山楂原花青素和Vc的IC50分别约为0.053mg/mL和0.11mg/mL;对O2-.,山楂原花青素和VC的IC50分别约为0.05mg/mL和0.17mg/mL。在脂质体体系中,山楂原花青素抑制脂质过氧化的能力远大于VE。     

西兰花酵素在发酵过程中生化指标变化及其抗氧化活性研究

以西兰花作为发酵原料,通过加入酵母菌、乳酸菌、醋酸杆菌复合发酵,研究西兰花酵素发酵过程中生化指标以及抗氧化性变化。其中,以p H值、菌落总数、总糖、乙醇、乳酸和乙酸作为生化指标考察西兰花酵素发酵过程中的变化;通过测定总酚、DPPH自由基清除率、超氧化物歧化酶(SOD)、氧自由基吸收能力(ORAC)作为抗氧化性变化指标。研究表明:在发酵过程中,p H值不断降低,由最初的4.49±0.02降低到3.51±0.03;菌落总数在第3 d最高,为9.03(±0.45)×10~7 CFU/m L;总糖被微生物利用消耗,由213.20±0.12 mg/m L降低到79.24±0.07 mg/m L;最终乙醇、乳酸和乙酸含量分别为28.23±0.06 mg/m L、7.89±0.05 mg/m L和11.66±0.05mg/m L;而抗氧化性指标总酚、DPPH自由基清除率、SOD和ORAC在前7 d处于上升趋势,7 d后趋于稳定。其中,DPPH自由基清除率、ORAC与总酚有正相关性(p0.01)。相对于实验室自制桑葚酵素,DPPH自由基清除率较高,抗氧化性较好。     

Nutritional composition and antioxidant properties of protein hydrolysates prepared from echinoderm byproducts

Protein hydrolysates were prepared from echinoderm byproducts, including viscera (SCV) of Atlantic sea cucumber ( Cucumaria frondosa ) and digestive tract (UDT) and non-commercial grade gonads (UGN) of green sea urchin ( Strongylocentrotus droebachiensis ). Enzymatic hydrolysis was performed on defatted materials using Alcalase^® 2.4L (0.75% w/w) and reaction was carried out overnight (∼16 h, 55 °C, pH 8.0). Freeze-dried hydrolysates were analysed for their nutritional composition, nitrogen solubility index and antioxidant activity. Degree of hydrolysis was low, with values of 5.6%, 4.6% and 7.0% for SCV, UDT and UGN, respectively. Hydrolysates showed high protein content (∼55%), high proportion of essential amino acids (∼35% of total amino acids) and good solubility (nitrogen solubility index ≈ 68%). They contained variable concentrations of major and trace elements with a predominance of Na and K. Hydrolysates showed apparent antioxidant activities in both ORAC assay (267–421 μmol TE g⁻¹) and inhibition of lipid oxidation test (54–57%). Antioxidant activities were thought to be associated with the presence of antioxidant peptides in hydrolysates. Our results showed that hydrolysates from Atlantic sea cucumber and green sea urchin byproducts might serve as alternative sources of dietary proteins, with good nutritional composition, high solubility and interesting protection against oxidative stress.     

人心果叶不同极性组分的抗氧化与抗菌活性

通过体外DPPH自由基、ABTS自由基清除能力和总抗氧化能力评价人心果叶不同极性萃取物(石油醚相、乙酸乙酯相、正丁醇相、水相)的抗氧化活性,并探究各极性组分对金黄色葡萄球菌、枯草芽孢杆菌和大肠杆菌的抑制能力.结果表明:乙酸乙酯组分的体外抗氧化活性最强,清除DPPH自由基能力IC50值为(0.019±0.010)mg/m...     

Antioxidant,Antibacterial, and Antiproliferative Activities of Free and Bound Phenolics from Peel and Flesh of Fuji Apple

This study was conducted to investigate the antioxidant, antibacterial, and antiproliferative activities of flesh free (FF), flesh bound (FB), peel free (PF), and peel bound (PB) phenolics from Fuji apple. The PB, which had highest total phenolic contents (126.15 ± 2.41 mg/100 g wet weight) and lowest total carbohydrate contents (34.68 ± 2.78 mg/100 g wet weight), showed the strongest 2,2’‐azinobis‐(3‐ethylbenthiazoline‐6‐sulphonate) (ABTS) radical scavenging activity (EC₅₀ = 0.36 ± 0.02 mg/mL), 1,1‐diphenyl‐2‐picryhydrazyl (DPPH) radical scavenging activity (EC₅₀ = 0.26 ± 0.01 mg/mL), and ferric reducing antioxidant power (Ferric reducing antioxidant power; EC₅₀ = 0.19 ± 0.02 mg/mL) compared with those of FF, FB, and PF. The PB also showed the strongest antibacterial activities on Escherichia coli, Staphylococcus aureus, and Listeria monocytogenes and it also showed the highest antiproliferative effects on Caco‐2 human colonic cancer cell (EC₅₀ = 1.44 ± 0.01 mg/mL) and Hela human cervical cell (EC₅₀ = 2.81 ± 0.01 mg/mL). Both free and bound phenolics from Fuji apple showed good antioxidant, antibacterial, and antiproliferative activities in our study, and bound phenolics had significantly higher activities compared with those of free phenolics.     

软枣猕猴桃多糖的分离纯化及抗氧化活性测定

对微波辅助提取的软枣猕猴桃多糖进行分离纯化并对各纯化组分的抗氧化活性进行测定。利用DE-AE-纤维素阴离子交换层析对软枣猕猴桃多糖进行初步分离,得到1个水洗组分和3个盐洗组分;利用Sephade-xG-100、G-200凝聚柱层析对其进行进一步分离纯化。结果表明:4个组分都为均一多糖且都不含有蛋白质;软枣猕猴桃多糖对DPPH自由基和羟基自由基具有一定的清除能力,对超氧阴离子自由基的清除能力很弱,盐洗组分的抗氧化活性明显优于水洗组分;0.1盐洗组分(0.1 mol/L NaCl溶液洗脱的组分)、0.2盐洗组分(0.2 mol/L NaCl溶液洗脱的组分)、0.3盐洗组分(0.3 mol/L NaCl溶液洗脱的组分)、Vc清除DPPH自由基的IC50分别为0.57、1.61、1.18、0.03 mg/mL;清除羟基自由基的IC50分别为1.5、5.6、2.7、0.2 mg/mL;0.1盐洗组分为软枣猕猴桃多糖中主要的抗氧化活性组分。     

Anti‐proliferative activity of bovine blood hydrolysates towards cancer cells in culture

Four proteins, α/β globulin, serum albumin, γ‐globulin and fibrinogen, were isolated from bovine blood and hydrolysed using papain. Hydrolysates were assessed for non‐cellular and cellular antioxidant activity. The anti‐proliferative activity of hydrolysed fractions was assessed in a number of cancer cell lines including U937 lymphoma cells, MCF‐7 breast cancer cells, HepG2 hepatocytes and Caco‐2 epithelial colorectal adenocarcinoma cells. Anti‐inflammatory activity of the hydrolysates was also assessed. Hydrolysates generated from γ‐globulin or fibrinogen had significant antioxidant activity in non‐cellular assays. Hydrolysates were also found to be highly toxic to different cancer cell lines, in particular U937 lymphoma cells when assessed using the MTT assay. The fibrinogen hydrolysate was the most toxic sample and toxicity appeared to correlate with its non‐cellular antioxidant activity. None of the hydrolysates had significant anti‐inflammatory activity. The high cytotoxicity of the γ‐globulin and the fibrinogen hydrolysates towards cancer cells may indicate a potential use as anti‐proliferative agents.     

桑叶蛋白抗氧化肽的酶法制备

为了提高桑叶蛋白MLP的抗氧化活性,用碱性蛋白酶Alcalase、复合蛋白酶Protamex、木瓜蛋白酶Papain、风味蛋白酶Flavourzyme、中性蛋白酶Neutrase及胰蛋白酶Trypsin等6种蛋白酶对MLP进行单酶酶解及双酶、三酶复合酶解,并对酶解前后的化学组成、分子量分布、多肽得率、氨基酸组成、自由基清除能力、还原能力等进行对比分析。结果表明,MLP主要由分子量大于6.5 ku的大分子肽及蛋白质组成,酶解物则主要由分子量为0.3~0.6 ku的小肽及0.6~6.5 ku的多肽组成;相较于过度酶解,适度酶解能更好的改善MLP的抗氧化活性;多肽得率与自由基清除能力显著正相关(r=0.916~0.985);6种蛋白酶中,碱性蛋白酶、中性蛋白酶及复合蛋白酶的酶解物抗氧化活性显著优于MLP及其他三种蛋白酶解物;中性蛋白酶单独酶解物的抗氧化活性显著优于双酶、三酶复合酶解物。对中性蛋白酶的单酶酶解条件进行优化,结果表明底物浓度为20 mg/mL,E/S为1%(W/W),用中性蛋白酶酶解2 h所得的酶解物(NH)的抗氧化活性最高,后期研究中可选用中性蛋白酶制备桑叶蛋白抗氧化肽。NH或许可以作为食品中较有潜力的抗氧化剂。     

用化学发光法分析燕麦发芽前后酚类物质抗氧化活性

对燕麦种子进行发芽实验6 d,对原样、6 d籽粒、6 d芽和6 d根中的酚类物质进行提取纯化,采用化学发光法对不同部位纯化物清除活性氧自由基的能力进行测定。结果表明:原样、6 d籽粒、6 d芽和6 d根纯化物在不同体系中均表现出良好的抗氧化活性,其清除超氧阴离子的IC50值分别为0.952、0.702、3.248、1.060 mg/mL,清除羟基自由基的IC50值分别为8.80、3.31、13.69、11.68μg/mL,清除双氧水的IC50值分别为10.97、8.64、13.05、9.61μg/mL,可见发芽过程使燕麦籽粒在3个体系中的抗氧化活性均有所提高,而燕麦芽的抗氧化活性相对籽粒和根较差。     

三种天然来源黄酮物质抗氧化活性和抑制胰脂肪酶活性的研究

以葛根黄酮、沙棘叶黄酮和山楂叶黄酮为研究对象,在不同体系中评价了总抗氧化能力、DPPH自由基清除活性、ABTS自由基清除活性及还原能力,同时评价了抑制胰脂肪酶活性的能力。结果表明:在不同体系中三种黄酮物质都呈现较强抗氧化活性,其中山楂叶黄酮总抗氧化能力最强,沙棘叶黄酮清除DPPH自由基(IC50 0.057±0.004)mg/m L和清除ABTS(IC50 0.096±0.014)mg/m L自由基活性最强,山楂叶黄酮与葛根黄酮呈现较强的还原能力,三种黄酮物质都呈现一定的抑制胰脂肪酶活性,沙棘叶黄酮活性最强。该研究为天然植物资源的综合利用提供了理论的支撑。     

玉米麸皮阿拉伯木聚糖咖啡酸酯的制备及其抗氧化活性

利用碱-H2O2法从玉米麸皮中提取出阿拉伯木聚糖（CAX），将咖啡酸（CA）通过酯键连接到CAX上得到阿拉伯木聚糖咖啡酸酯（CA-CAX），用红外，核磁氢谱、碳谱确定了结构，用高效液相色谱确定了CA的取代度，调整CA用量，得到不同取代度的CA-CAX-s（s表示取代度），并用高效凝胶渗透色谱测定不同取代度的分子量，CAX、CA-CAX-0.27、CA-CAX-0.51和CA-CAX-0.65的重均分子量分别为3.07×105、3.09×105、3.36×105和3.68×105 g/mol。通过紫外检测表明，CA-CAX-s在UVB具有较高的紫外吸收，而且CA-CAX-s水溶液的黏度明显增大，紫外吸收及黏度的大小均随CA含量的增加而增大。CA-CAX-0.27、CA-CAX-0.51和CA-CAX-0.65清除DPPH自由基的IC50分别为0.28、0.13和0.12 mg/mL。脂质过氧化物的检测CA-CAX-0.65用量为4 mg/mL时可以将丙二醛（MDA）的含量从120 ng/mL降低到最低值51.80 ng/mL。抗氧化能力指数（ORAC）测定结果表明改性后CA-CAX-s可将荧光消失的时间从13 min延长至60 min以上，ORAC值也从7上升至62.83。CA-CAX的抗氧化性较CAX有明显提高，而且咖啡酸含量越高CA-CAX-s的抗氧化性越好。     

糖蜜酒精废液色素物的抗氧化活性研究

采用羟自由基、亚硝酸盐、超氧阴离子自由基和DPPH.体系初步研究2个典型的糖蜜酒精废液色素物的抗氧化活性。结果表明:色素试样A和色素试样B都具有一定的抗氧化活性,随着浓度的增加其抗氧化能力也相应增加;且色素物经提纯后其抗氧化能力显著提高,在羟自由基体系中,试样B的IC50约为4.5 mg/mL;在DPPH.体系中,试样B对DPPH.的清除率的IC50约为0.07 mg/mL。     

高固形物浓度对酵母酶解及其产物抗氧化性的影响

高固形物浓度的酶解是近年来国际食品探究的热点之一。本文利用木瓜蛋白酶水解不同固形物浓度的活性面包酵母,并对酶解液的氨氮、总氮、可溶固形物含量、还原糖、总糖、渗透压、抗氧化活性以及褐变程度进行了检测,探究高固形物浓度对酵母酶解及其产物抗氧化性的影响。结果表明,随着固形物浓度的提高,酵母酶解液中的氨氮、总氮,可溶性固形含量、还原糖、总糖、渗透压随之提高,提高固形物浓度有利于提高酵母酶解效率。通过对酵母酶解液抗氧化活性的测定发现,固形物浓度为30%时,酶解液具有较高的DPPH和羟自由基清除活性,酶解13 h时,其IC50值分别为0.83±0.09 mg/mL和21.53±1.18 mg/mL;酶解21 h时,其IC50值分别为1.01±0.13 mg/mL和23.17±1.33 mg/mL。在高浓度固形物酶解液中,适当添加SDS有助于降低其褐变程度。     

Amino Acid Composition and Antioxidative Peptides from Protein Hydrolysates of Yellow Stripe Trevally (Selaroides leptolepis)

ABSTRACT:  Hydrolysates from yellow stripe trevally meat with 15% degree of hydrolysis (DH) obtained using Alcalase (HA) and Flavourzyme (HF) following pH-stat method were characterized. Both hydrolysates, HA and HF, contained glutamic acid and glutamine as the major amino acids, while glycine was the dominant amino acid in fish flesh. Hydrolysates were also rich in aspartic acid, asparagine, alanine, lysine, and leucine. Essential amino acid/nonessential amino acid ratios were 0.55, 0.63, and 0.62 for flesh, HA, and HF, respectively. After separation on a Sephadex G-50 column, antioxidative activity of hydrolysate fractions was determined as Trolox equivalent antioxidant capacity. The fraction of HF with molecular weight (MW) of 1.77 kDa exhibited the strongest antioxidative activity, compared with other fractions. Among all fractions of HA, the one having a MW of 2.44 kDa showed the highest antioxidative activity. Thereafter, the selected Sephadex G-50 fractions from both HA and HF were further chromatographed using a Sephadex C-25 column, followed by HPLC. MW of antioxidative peptides from HA and HF determined by Maldi TOF/TOF was 656 and 617 Da, respectively. However, peptides isolated from both HA and HF possessed a lower antioxidative activity than Trolox at the same concentration ( P < 0.05). HA and HF prevented DNA oxidative damage in Fenton reaction system tested by in vitro plasmid DNA relaxation assay. These results indicate that hydrolysates from yellow stripe trevally can be used as an important source of amino acids and serve as alternative natural antioxidants.     

牡蛎蛋白酶解多肽降糖及抗氧化活性评价

目的:利用化学方法评价9种酶对牡蛎蛋白酶解所得多肽降血糖和抗氧化活性的影响,筛选最佳酶的种类。方法:以牡蛎蛋白酶解多肽对α-淀粉酶抑制率为指标评价其体外辅助降血糖活性,以DPPH·清除率、超氧阴离子抑制率为指标评价牡蛎蛋白酶解多肽的体外抗氧化活性,筛选出最佳用酶。结果:风味蛋白酶得到的多肽对α-淀粉酶的抑制效果最好,5 mg/mL时抑制率达到67.13%,IC₅₀值为3.806 mg/mL;糜蛋白酶酶解得到的多肽对DPPH·的清除率最高,2 mg/mL时清除率为58.09%,IC₅₀值为1.16 mg/mL;同时,糜蛋白酶酶解得到的多肽对超氧阴离子的抑制率也最高,2 mg/mL时抑制率为53.64%,IC₅₀值为1.75 mg/mL。结论:风味蛋白酶和糜蛋白酶酶解所得牡蛎多肽在降糖和抗氧化方面具有较大的潜力,为进一步开展牡蛎蛋白酶解多肽的研究提供参考。     

响应面优化紫果西番莲叶多酚超声辅助提取工艺及其抗氧化活性

以紫果西番莲叶为对象,研究其多酚提取工艺及抗氧化活性。在单因素实验基础上采用Box-Behnken响应面分析法优化紫果西番莲叶多酚的提取工艺,考察液料比、提取时间、超声功率和超声温度对其多酚提取量的影响,以清除DPPH自由基和·OH能力评价紫果西番莲叶多酚的抗氧化活性。结果表明,最佳提取条件为：液料比36：1 mL/g、提取时间54 min、超声功率350 W和超声温度70℃,此时紫果西番莲叶中多酚提取量为（13.19±0.17） mg/g。抗氧化活性结果表明,紫果西番莲叶多酚具有较好的抗氧化活性,其清除DPPH自由基和·OH的半抑制浓度（IC₅₀）分别为0.058和0.144 mg/mL。     

三种食用菌提取物体外抗氧化与降血糖活性研究

目的:为评价三种食用菌体外抗氧化与降血糖作用。方法:采用水杨酸显色法、DPPH·显色法、铁氰化钾显色法测定三种食用菌及副产物(竹荪、竹荪菌托、茶树菇、松乳菇)提取物的抗氧化能力,再通过α-淀粉酶和α-葡萄糖苷酶活性抑制作用分析提取物的降血糖活性。结果:在实验浓度(0.5~5 mg/mL)范围内三种食用菌及副产物的提取物具有一定的抗氧化和降血糖作用,且存在明显的量效关系。抗氧化以V_C作为阳性对照,降血糖组间进行对照。当浓度达到5 mg/mL时,茶树菇提取物对·OH和DPPH·的清除率最高可达89.45%和87.81%,对Fe³⁺的还原能力与V_C相近,IC₅₀均为1.04 mg/mL;而竹荪和竹荪菌托提取物对·OH(45.19%和36.04%)、DPPH·(44.30%和36.81%)的清除率和对Fe³⁺的还原能力(46.61%和48.09%)均较弱,且IC₅₀值均超出实验浓度。当浓度达到5 mg/mL时,茶树菇提取物对α-淀粉酶和α-葡萄糖苷酶活性的抑制率分别62.15%和57.08%,IC₅₀值为3.82和4.10 mg/mL;松乳菇提取物对两种酶的抑制率分别为83.52%和75.43%,IC₅₀值为2.22和2.53 mg/mL;而竹荪和竹荪菌托提取物对α-淀粉酶(15.15%和24.56%)和α-葡萄糖苷酶(26.20%和23.41%)活性的抑制率均较低,且IC₅₀值均超出实验浓度。结论:茶树菇提取物降血糖和抗氧化作用均较强,而松乳菇提取物的降血糖作用较强而抗氧化作用较弱,竹荪和竹荪菌托提取物的抗氧化活性和降血糖活性均较弱。     

Antioxidant, antihypertensive and antimicrobial properties of ovine milk caseinate hydrolyzed with a microbial protease

BACKGROUND: Bioactive peptides might be released from precursor proteins through enzymatic hydrolysis. These molecules could be potentially employed in health and food products. In this investigation, ovine milk caseinate hydrolysates obtained with a novel microbial protease derived from Bacillus sp. P7 were evaluated for antioxidant, antimicrobial, and angiotensin I‐converting enzyme (ACE)‐inhibitory activities. RESULTS: Antioxidant activity measured by the 2,2′‐azino‐bis‐(3‐ethylbenzothiazoline)‐6‐sulfonic acid method increased with hydrolysis time up to 2 h, remaining stable for up to 4 h. Hydrolysates showed low 2,2‐diphenyl‐1‐picrylhydrazyl radical‐scavenging abilities, with higher activity (31%) reached after 1 h of hydrolysis. Fe²⁺‐chelating ability was maximum for 0.5 h hydrolysates (83.3%), decreasing thereafter; and the higher reducing power was observed after 1 h of hydrolysis. ACE‐inhibitory activity was observed to increase up to 2 h of hydrolysis (94% of inhibition), declining afterwards. 3 h hydrolysates were shown to inhibit the growth of Bacillus cereus, Corynebacterium fimi, Aspergillus fumigatus, and Penicillium expansum. CONCLUSION: Ovine caseinate hydrolyzed with Bacillus sp. P7 protease presented antioxidant, antihypertensive, and antimicrobial activities. Hydrolysis time was observed to affect the evaluated bioactivities. Such hydrolysates might have potential applications in the food industry. Copyright © 2011 Society of Chemical Industry     

石斛粉葛咀嚼片的制备及其抗氧化活性

以石斛和粉葛为原料,经超微粉碎、配料、湿法造粒、干燥、整粒、压片等工序制成咀嚼片。考察了原料比、辅料比、乙醇浓度、60%乙醇添加量、硬脂酸镁添加量对咀嚼片感官品质的影响,在单因素实验基础上,采用L₁₆(4⁵)正交试验优化咀嚼片配方;以DPPH·清除能力、ABTS⁺·清除能力、总抗氧化能力为模型评价咀嚼片抗氧化活性。结果表明,石斛粉葛咀嚼片最佳工艺配方为:原料中石斛:粉葛为1:4,原辅料比[(石斛+粉葛):辅料(玉米淀粉+菊粉+木糖醇+甘露醇)]为1:1.5,辅料配比(玉米淀粉:菊粉:木糖醇:甘露醇)为4:3:1:1,润湿剂60%乙醇的添加量为0.4 mL/g,硬脂酸镁1.5%,咀嚼片感官评分为93.7±0.03分。石斛粉葛咀嚼片水提液、石斛粉葛咀嚼片醇提液与抗坏血酸(V_C)的清除DPPH·的IC₅₀值分别为(3.067±0.1095)、(3.512±0.0945)、(0.06337±0.0286) mg/mL;石斛粉葛咀嚼片水提液、石斛粉葛咀嚼片醇提液与V_C的清除ABTS⁺·的IC₅₀值分别为(5.529±0.8175)、(5.380±0.7915)、(0.2772±0.0345) mg/mL;石斛粉葛咀嚼片水提液、醇提液、V_C在浓度为2 mg/mL时,总抗氧化能力分别为0.258、0.188、0.494。石斛粉葛咀嚼片有一定的抗氧化活性,石斛与粉葛有协同抗氧化作用。