复合酶法制备澳洲坚果蛋白肽及其抗氧化活性研究

本研究以前期制备的澳洲坚果蛋白为原料,经复合酶（木瓜蛋白酶和中性蛋白酶）酶解制备澳洲坚果蛋白肽,采用水解度为指标,利用单因素试验与正交试验考察各酶解因素对澳洲坚果蛋白水解度的影响,同时通过不同分子量（3、10、30 kDa）的超滤离心管对制备的蛋白肽进行初步的分离,并基于DPPH自由基清除能力对不同分子量的澳洲坚果蛋白肽的抗氧化活性进行评价。结果表明：各酶解因素对复合酶酶解制备澳洲坚果蛋白水解度的影响依次为酶解初始pH>复合酶配比>酶添加量>酶解时间;最佳复合酶酶解条件为复合酶配比1∶5、酶添加量12 000 U/g、酶解液初始pH 9.0、酶解时间360 min,在此条件下澳洲坚果蛋白的水解度为21.88%;同时,通过分析不同分子量的澳洲坚果蛋白肽组分发现,不同分子量的澳洲坚果蛋白肽均具有抗氧化活性,分子量在3~10 kDa的肽段组分具有较强的抗氧化能力,其DPPH自由基清除能力达到80.97%,且随着蛋白肽组分浓度的增加,其抗氧化能力也逐渐增强。     

大豆蛋白呈鲜组分的制备及其性质研究

大豆经酶解后可产生呈现鲜味的物质。为了研究产品中鲜味的来源及产生鲜味组分的主要组成,本研究以大豆分离蛋白为原料,经风味蛋白酶改性,感官分析后发现,水解度达到43％时的酶解液呈鲜较强、苦味较弱;该酶解产物过截留分子量为10000Da,6000Da,3000Da的超滤膜,分成四个组分,发现是平均分子量小于3000Da的肽组份,而大于3000Da和小于500Da的组分只有微弱的鲜味,苦味和涩味明显。研究结果同时发现该酶解产物与肌苷酸间有显著风味增强效果。     

双酶解法提取大豆蛋白的工艺研究

以豆粕粉为原料,加入高效蛋白酶和胰蛋白酶进行水解研究,对反应温度、底物浓度、反应时间、pH值、酶的用量及酶加入间隔的时间等工艺参数进行优化,并分析了大豆多肽的含量及蛋白质的水解度与各影响因素之间的关系.经过优化得到的反应条件为温度45℃,pH 7.5,液固比7: 1,加酶量为高效蛋白酶和胰蛋白酶各0.2 g,反应时间8 h,加酶间隔时间3 h.在此条件下,酶解后的蛋白质含量达85%、水解度为17.72%.     

大豆小分子多肽制备工艺和质量标准的研究

采用酶法水解脱脂豆饼粕制备具有生物活性的大豆小分子多肽,确定了先以粗胰酶预酶解5%豆饼粕蛋白,再以中性微生物蛋白酶进一步水解提取大豆小分子多肽的工艺流程.粗胰酶酶解最佳条件:添加量为9 000 U·g-1,酶解温度55℃,pH 8.5,时间6 h.中性微生物蛋白酶水解粗胰酶乳最佳条件为:加酶量8 500 U·g-1,pH 7.5,温度45℃,时间2 h.在此条件下,肽得率可达到73.98%.同时还构建了大豆小分子活性多肽的质量检测标准.     

双酶法制备乳制品专用大豆分离蛋白的研究

采用Alcalace碱性内切蛋白酶及Flavourzyme复合风味蛋白酶进行双酶水解,确定了两种酶的最优酶系组合.第一步采用Alcalace酶解,以水解度为指标,正交实验结果显示,最优酶解工艺为:pH7.5,温度60℃,时间2 h,酶添加量0.9%,此时水解度可达到15.08%; 水解后不必灭酶,进行第二步Flavourzyme酶解,以苦味值为指标,采用添加量3.5%, 时间 2 h的水解.最终得到的乳品专用分离蛋白水解度为:17.88%,蛋白质含量:90.17%,无明显不良口味.     

Alcalase2．4L碱性内切蛋白酶改性大豆蛋白的工艺研究

以大豆分离蛋白为研究对象,采用碱性内切蛋白酶Alcalase 2.4L作为水解大豆分离蛋白的酶制剂,探讨碱性内切蛋白酶Alcalase 2.4L对大豆分离蛋白的影响.本实验以水解度和蛋白质分散性指数为评价指标,确定了Alcalase 2.4L酶解大豆分离蛋白的最佳酶解反应条件:加酶量0.004 8AU/g、pH值为7.4、底物浓度11%、反应温度65℃、酶解时间50min.该条件下大豆分离蛋白的分散性得到显著改善,蛋白质分散指数PDI值达到92.8%.     

糖基化大豆蛋白酶解物的分离纯化及耐消化稳定性的研究

以糖基化大豆蛋白为原料,经碱性蛋白酶酶解制得具有抑制致病菌粘附功能的糖肽,并分析功能性糖肽的消化稳定性。酶解物用Sephadex G-25层析可获得表观分子量分别为20 000 Da、6 500 Da和小于3 000 Da组分。对酶解物胃蛋白酶和胰蛋白酶体外模拟依次消化2 h后,20 000~6 500 Da的大豆糖肽分子量变化不大,较稳定,而分子量小于3 000 Da的大豆糖肽中有5%被消化,稳定性略有变化。说明糖基化大豆蛋白酶解物其功能性成分可以较稳定存在于消化系统。     

Protex7L中性蛋白酶改性大豆分离蛋白的工艺研究

利用中性蛋白酶Protex 7L对大豆分离蛋白进行改性研究,以水解度和蛋白质分散指数为评价指标,确定了中性蛋白酶Protex 7L改性大豆分离蛋白的最佳酶解反应条件:加酶量13.5AU/g大豆分离蛋白(SPI)、反应温度55℃、底物浓度为10%、pH值为7.0,酶解时间为1h.在上述条件下大豆分离蛋白的分散性得到显著改善,蛋白质分散指数(PDI值)达到91.8%.     

双酶法制备大豆降胆固醇活性肽的研究

通过比较4种酶对大豆分离蛋白的水解效果,并通过单因素及L9(34)正交试验优化其水解工艺条件,研究其最佳水解工具酶及最佳酶解参数。结果表明:木瓜蛋白酶和植物蛋白酶联合应用可作为大豆分离蛋白的水解工具酶;其最佳酶解参数为:酶解温度55℃、初始pH7.0、底物浓度12%、酶添加量8%、植物蛋白酶与木瓜蛋白酶的质量之比为1∶2,水解度可达14.20%;用双蛋白酶水解大豆分离蛋白,水解度为14.71%的产物降胆固醇活性最高,对胆固醇胶束溶解度的抑制率为61.67%。     

酶法制备大豆多肽的研究

本文研究了以Alcalase碱性蛋白酶和风味蛋白酶水解大豆蛋白制备大豆肽的工艺。确定了酶水解的最佳温度、底物浓度、酶与底物浓度比,得到了Alcalase碱性蛋白酶和风味蛋白酶水解大豆分离蛋白的最佳水解工艺。     

不同酶解程度的大豆分离蛋白在配制酱油中的应用

以大豆分离蛋白为原料,对不同酶解程度的大豆分离蛋白在配制酱油中的应用进行了研究。首先通过单因素试验确定了酶解大豆蛋白的工艺参数,然后对添加不同酶解程度的大豆分离蛋白配制酱油的质量进行了研究,研究结果表明:酶解温度为50℃、pH为7.0、酶解时间为5h条件下的大豆分离蛋白酶解产物最适合应用到配制酱油中。     

大豆功能肽的研究进展

大豆功能肽是以大豆分离蛋白或者豆粕为原料酶解生成的具有生理功能的小分子量肽类。大豆功能肽的分子量小、溶解性好,在食品工业中的广泛应用。并且,具有降低血清胆固醇、降低血压、消除疲劳作用和抗氧化等许多活性作用。本文对大豆功能肽的特性、制备方法以及生物学活性等方面进行综述。     

豆渣酶解工艺及其水解液发酵抗性菌株筛选

从工业化生产实际出发,探讨了豆渣的高效水解技术、酵母菌株的选育及其培养工艺。不同工艺条件下,采用纤维素酶和普鲁兰酶水解豆渣,以葡萄糖为标准测量水解后料液中糖含量,得出水解豆渣的最佳工艺条件:温度55℃,料液比为1∶24,先用普鲁兰酶水解,调至pH5.0,再用纤维素酶水解,调至pH5.5,普鲁兰酶3 h,纤维素酶1 h,时间比为3∶1,加酶总量为3%,普鲁兰酶∶纤维素酶为3∶1。用此条件对豆渣进行水解得到水解液,料液中含糖量最高位为160.7 mg·kg~(-1)。用含量为35%的水解液去培养抗性菌株,筛选的抗性菌株C发酵效果较好,酵母含量达18.49 g·L~(-1)。     

Muscle Protein Hydrolysates and Amino Acid Composition in Fish

Fish muscle, which accounts for 15%–25% of the total protein in fish, is a desirable protein source. Their hydrolysate is in high demand nutritionally as a functional food and thus has high potential added value. The hydrolysate contains physiologically active amino acids and various essential nutrients, the contents of which depend on the source of protein, protease, hydrolysis method, hydrolysis conditions, and degree of hydrolysis. Therefore, it can be utilized for various industrial applications including use in nutraceuticals and pharmaceuticals to help improve the health of humans. This review discusses muscle protein hydrolysates generated from the muscles of various fish species, as well as their amino acid composition, and highlights their functional properties and bioactivity. In addition, the role of the amino acid profile in regulating the biological and physiological activities, nutrition, and bitter taste of hydrolysates is discussed.     

Hydrolysis of glycoalkaloids fromSolanum tuberosum L. haulm by enzymes present in plant material and by enzyme preparation

Summary This paper deals with the kinetics of enzymatic hydrolysis of glycoalkaloids from potato (Solanum tuberosum L.) haulm. The hydrolysis was carried out by the action of the enzymes present in fresh haulm, juice of fresh haulm and in haulm dried at various temperatures. The highest degree of enzymatic hydrolysis of 90% was obtained during fermentation of haulm dried at 40 °C after 30 h incubation time. The enzyme preparation was obtained from the juice of fresh potato haulm by using capillary dialysator HM 16 (AQM 1681, 1.6 m² Hemofan 8 υ). The best degree of enzymatic hydrolysis by enzyme preparation, 68%, was achieved after 20 h time of incubation. The enzyme preparation from juice of fresh haulm was characterized by K_m of 0.70 mM at pH 5.5 and 35 °C.     

Antithrombotic Activity of Brewers’ Spent Grain Peptides and their Effects on Blood Coagulation Pathways

Antithrombotic activity of brewers’ spent grain peptides before and after simulated gastrointestinal digestion and their effects on blood coagulation pathways were evaluated. Two hydrolysates were produced using sequential enzymatic systems: alkaline protease + Flavourzyme (AF) and neutral protease + Flavourzyme (PF). Simulation of gastrointestinal digestion of AF and PF hydrolysates was made using porcine pepsin and pancreatin enzymes, obtaining the corresponding digested samples: AFD and PFD, respectively. Peptides were fractionated by ultrafiltration using a 1 kDa cut-off membrane. Hydrolysates had peptides with medium and low molecular weights (2100 and 500 Da, respectively), and Glu, Asp, Leu, Ala, and Phe were the most abundant amino acids. Gastrointestinal digested hydrolysates presented high proportion of small peptides (~500 Da), and higher amount of Val, Tyr, and Phe than hydrolysates. Mass spectrum (HDMS Q-TOF) of AFD-ultrafiltered fraction <1 kDa exhibited peptides from 500 to 1000 Da, which are not present in AF. PFD showed the generation of new peptides from 430 to 1070 Da. All samples showed thrombin inhibitory activity. However, no effect was observed on prothrombin time. Peptides <1 kDa from hydrolysates and digested samples delayed thrombin and thromboplastin time respect to the control (~63%). Also the samples showed thrombin inhibitory activity at common pathway level. Thus, brewers’ spent grain peptides exerted their antithrombotic activity by inhibiting the intrinsic and common pathways of blood coagulation. This is the first report to demonstrate that brewers’ spent grain peptides are able to delay clotting time after simulated gastrointestinal digestion.     

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.