基于模拟胃肠道消化的云南民族乳制品蛋白肽研究

乳扇、乳饼和奶渣是云南民族传统乳制品,具有历史悠久、特色鲜明、蛋白质含量高等特点.本研究基于模拟胃肠道消化,采用液相色谱-串联质谱、氨基酸分析仪研究乳扇、乳饼和奶渣的肽谱及游离氨基酸含量,并借助蛋白肽数据库分析潜在的生物活性肽.结果表明,乳扇蛋白肽221条,分子质量集中在500～750Da,潜在的功能活性肽包括血管紧张...     

驼乳和牛乳乳清蛋白抑菌肽的分离纯化及抑菌活性的比较

本文以驼乳和牛乳的乳清蛋白为原料,经胃蛋白酶水解后,通过超滤及葡聚糖凝胶层析对其水解物进行分离纯化,其后对获得的蛋白肽进行抑菌活性、二喹啉甲酸法(BCA)蛋白浓度、相对分子质量及氨基酸组成的测定。结果表明:经超滤获得的驼乳和牛乳分子量<3 kDa的多肽片段-F3具有最强的抑菌活性,将F3(<3 kDa)组分通过层析处理得到的驼乳G-25-2和牛乳G-25-2抑菌肽纯度较高(BCA蛋白浓度分别为95.60%和95.32%);驼乳G-25-2和牛乳G-25-2组分对大肠埃希氏菌和金黄色葡萄球菌均有抑菌作用,最小抑菌质量浓度分别均为32.50和65.00 mg/mL;氨基酸分析结果显示,高活性抗菌肽中的总碱性氨基酸和总疏水性氨基酸含量最高,驼乳G-25-2中分别为32.80%和65.76%,牛乳G-25-2中分别为31.77%和58.70%。本研究结果表明,驼乳与牛乳均具有抑菌效果,且其抑菌能力高于牛乳,为今后研究驼乳抑菌肽的深入研究提供理论参考。     

燕麦分离蛋白消化特性和消化产物对STC-1细胞分泌胆囊收缩素的影响

为研究燕麦分离蛋白的消化特性及其消化产物对肠内分泌细胞分泌胆囊收缩素(CCK)的影响,以燕麦为原料,采用碱提酸沉法得到燕麦分离蛋白,分析燕麦分离蛋白在模拟胃肠道消化过程中的分子质量变化、氮释放规律、消化产物的氨基酸组成,计算氨基酸评分、化学评分和必需氨基酸指数,并以STC-1细胞为肠内分泌细胞模型评价消化产物对STC-1细胞分泌CCK的影响。实验结果表明:燕麦分离蛋白经胃肠消化后,消化产物的分子质量小于10kDa,释放的可溶性氮的比例为90.11%,消化产物可溶性部分中游离氨基酸的比例为22.8%,肽的比例为67.31%,并且肽的分子质量主要在1000Da以下(约74%)；燕麦分离蛋白消化产物中必需氨基酸总量占38.75%,必需氨基酸与非必需氨基酸的比值为0.63,且必需氨基酸指数(0.95)大于0.90。燕麦分离蛋白消化产物对STC-1细胞影响的实验结果表明,燕麦分离蛋白消化产物对STC-1细胞生长具有显著的促进作用,且能够增加CCK的合成和分泌。研究结果表明,燕麦分离蛋白作为一种优质的蛋白质原料,不仅具有优良的营养功能,而且具有促进肠内分泌细胞分泌CCK的生物活性,在食品领域具有较大的应用潜力。     

Amino acid composition and biological value of pastries with protein-rich additives

The authors studied amino acid composition of confectionery (bisquits) enriched with dry fat-free milk, dried buttermilk, dry whey and soya bean flour. The biological value of the products was estimated by the sum of essential amino acids, by the ratio of essential amino acids and total nitrogen, by the chemical score and the variation coefficient of the amino acid score. It has been established that confectionery enriched with dry fat-free milk and dried buttermilk contain more lysine than those enriched with soya bean flour. The balance of amino acids is improved in the products enriched with dry fat-free milk and dried buttermilk. To improve the amino acid balance and increase protein content in food products it iz recommended that by-products of milk manufacturing be mildly used.     

含重组人乳铁蛋白乳粉蛋白质营养学评价

目的评价牛乳腺生物反应器表达的重组人乳蛋白乳粉蛋白质的营养价值。方法选用100只清洁级刚断乳(出生后20~23 d)SD大鼠(雌、雄各半),按性别、体质量随机分为5组:重组人乳蛋白乳粉组、普通乳粉组、酪蛋白乳粉组、牛乳铁蛋白乳粉组、重组人乳铁蛋白乳粉组,分别喂饲相应饲料28 d,观察大鼠的进食量、体质量,测定血常规、血生化情况,试验末期处死动物,称量脏器重量并对脏器进行病理学检查,计算蛋白功效比和校正蛋白功效比,对氨基酸评分。结果重组人乳铁蛋白乳粉雄性动物组总体蛋白功效比值差异有统计学意义(P0.05),但重组人乳铁蛋白乳粉组雄性和其他对照组差异无统计学意义(P0.05)。雌性动物重组人乳铁蛋白乳粉组和其他对照组蛋白功效比值差异无统计学意义(P0.05)。结论重组人乳铁蛋白乳粉的蛋白功效和其他组相比并无较大区别,氨基酸评分结果显示苯丙氨酸和酪氨酸为第一限制氨基酸,与普通乳粉一样。     

不同基料的婴幼儿配方奶粉蛋白质营养评价

目的:旨在评价不同基料的婴幼儿配方奶粉蛋白质营养差异。方法:通过邻苯二醛(OPA)-9-芴甲基氯甲酸甲酯(FMOC)在线柱前衍生利用高效液相色谱方法测定氨基酸组成及含量,以WHO/FAO推荐的氨基酸理想模式为基准,选择氨基酸评分(AAS)、氨基酸比值(RC)、氨基酸比值系数分(SRC)、必需氨基酸指数(EAAI)及灰色关联度法5项指标,通过加权评分法对市售不同品牌的婴幼儿配方牛、羊奶粉进行综合评价。结果表明:加权评分及各分项指标比较显示,母乳均为最优,其必需氨基酸组成与理想模式吻合度最佳,蛋白质质量最好,利用率最高,即表明母乳是婴幼儿的最佳营养来源,同时也表明该综合评价方法可信;采集的各配方奶粉样品第一限制性氨基酸均为蛋氨酸+胱氨酸,所有样品必需氨基酸指数均在90以上,均属于优质蛋白源;所有样品中,综合得分最高的为配方羊奶粉样品C为74.78,配方牛、羊奶粉和理想氨基酸模式均存在一定差距,羊奶粉较优,整体营养评价:母乳>配方羊奶粉>配方牛奶粉。     

杏仁蛋白肽功能活性及质量安全控制研究进展

杏仁蛋白是杏仁制油后的主要副产物之一,主要应用于食品加工中,或在加工过程中充当辅助原料。杏仁蛋白营养价值高,但其水溶性低,氨基酸组成不合理,在食品工业中的发展受到限制。酶解杏仁蛋白制得的杏仁蛋白肽改良了蛋白质特性,并且具有众多功能活性,是提高杏仁蛋白深加工和开发其高附加值的重要手段。生物活性肽是目前研究热点,其制备方法、作用机制和功能活性得到广泛关注,杏仁蛋白肽作为优质生物活性肽,则具有很大的发展前景。本文对杏仁蛋白肽的主要制备方法及抗氧化、降血脂、降血糖、降血压等主要功能活性进行综述,对影响杏仁蛋白肽质量的危害进行分析并提出解决措施,最后总结了杏仁蛋白肽目前存在的问题以及今后发展前景,对杏仁蛋白肽工业化生产、药用价值的开发具有重要意义。     

Antioxidant activity of yoghurt peptides: Part 2 – Characterisation of peptide fractions

The aim of the present study was to elucidate previous findings showing that peptide fractions isolated from yoghurt had antioxidant effects. Therefore, peptides and free amino acids released during fermentation of milk were characterised. Yoghurt samples were stripped from sugars and lactic acid and subsequently fractionated by ultra filtration using membranes with cut off sizes of 30, 10 and 3 kDa. The peptides in these fractions were identified by LC–MS/MS. The identified peptides comprised a few N-terminal fragments of αs₁-, αs₂-, and κ-casein, and several fragments from β-casein. Almost all the peptides identified contained at least one proline residue. Some of the identified peptides included the hydrophobic amino acid residues Val or Leu at the N-terminus and Pro, His or Tyr in the amino acid sequence, which is characteristic of antioxidant peptides. In addition, the yoghurt contained a considerable amount of free amino acids such as His, Tyr, Thr and Lys, which have been reported to have antioxidant properties. Thus, our findings confirm that the antioxidant effects of the peptide fractions from yoghurt are due to the presence of certain peptides and free amino acids with recognised antioxidant activity in these fractions.     

乳蛋白生物活性肽的研究概述

对源于乳蛋白的生物活性肽作一介绍,主要包括：阿片样肽,降血压肽,抗血栓肽及免疫促进肽等。这些活性肽的发现为今后进一步利用乳蛋白资源,生产功能食品基料或药品提供了一条新的途径。     

重量法结合氨基酸分析法测定婴幼儿配方乳粉中小分子蛋白肽含量

目的:建立婴幼儿配方乳粉中小分子肽含量的定量分析方法。方法:分别采用凯氏定氮法、重量法、离子交换色谱等方法测定婴幼儿配方乳粉中总蛋白、高分子蛋白和游离氨基酸含量,通过计算求得小分子蛋白肽含量。结果:高分子蛋白检测精密度RSD (n=6)为0.74%;17种氨基酸回收率为91.0%～103.2%,检测结果的相对偏差为0.6%～2.5%;小分子蛋白肽添加回收率为95.2%～98.2%。结论:所建方法精密度和回收率良好,可用于婴幼儿配方乳粉中小分子肽含量的测定。     

Impact of ultrafiltration and nanofiltration of an industrial fish protein hydrolysate on its bioactive properties

BACKGROUND: Numerous studies have demonstrated that in vitro controlled enzymatic hydrolysis of fish and shellfish proteins leads to bioactive peptides. Ultrafiltration (UF) and/or nanofiltration (NF) can be used to refine hydrolysates and also to fractionate them in order to obtain a peptide population enriched in selected sizes. This study was designed to highlight the impact of controlled UF and NF on the stability of biological activities of an industrial fish protein hydrolysate (FPH) and to understand whether fractionation could improve its content in bioactive peptides. RESULTS: The starting fish protein hydrolysate exhibited a balanced amino acid composition, a reproducible molecular weight (MW) profile, and a low sodium chloride content, allowing the study of its biological activity. Successive fractionation on UF and NF membranes allowed concentration of peptides of selected sizes, without, however, carrying out sharp separations, some MW classes being found in several fractions. Peptides containing Pro, Hyp, Asp and Glu were concentrated in the UF and NF retentates compared to the unfractionated hydrolysate and UF permeate, respectively. Gastrin/cholecystokinin‐like peptides were present in the starting FPH, UF and NF fractions, but fractionation did not increase their concentration. In contrast, quantification of calcitonin gene‐related peptide (CGRP)‐like peptides demonstrated an increase in CGRP‐like activities in the UF permeate, relative to the starting FPH. The starting hydrolysate also showed a potent antioxidant and radical scavenging activity, and a moderate angiotensin‐converting enzyme (ACE)‐1 inhibitory activity, which were not increased by UF and NF fractionation. CONCLUSION: Fractionation of an FPH using membrane separation, with a molecular weight cut‐off adapted to the peptide composition, may provide an effective means to concentrate CGRP‐like peptides and peptides enriched in selected amino acids. The peptide size distribution observed after UF and NF fractionation demonstrates that it is misleading to characterize the fractions obtained by membrane filtration according to the MW cut‐off of the membrane only, as is currently done in the literature. Copyright © 2010 Society of Chemical Industry     

鲣鱼蛋白肽谱效关系研究

采用鲣鱼为原料,以蛋白质回收率为指标,酶解制备不同工艺条件的样品。通过测定其黄嘌呤氧化酶(XOD)抑制活性、ORAC值、分子质量分布图谱和总氨基酸含量,构建鲣鱼蛋白肽体外化学活性与其分子质量分布图谱、总氨基酸含量图谱之间的谱效关系。结合超高效液相-质谱联用(LC-MS/MS)方法研究其降尿酸肽和抗氧化肽的分布。研究表明,鲣鱼蛋白肽的XOD抑制活性与其ORAC值具有显著的相关性。由多肽分子质量<1ku所占含量的分布区段和脂肪族氨基酸的含量可初步预测鲣鱼蛋白肽的化学活性。质谱分析表明,纯化组分的质谱基峰图在不同时间段的信号强度与鲣鱼蛋白肽的降尿酸活性和抗氧化活性具有明显的相关性。     

响应面法优化偃松松仁蛋白肽乳饮料的制备工艺

以偃松松仁为原料研究偃松松仁蛋白肽乳饮料的制备工艺。采用碱性蛋白酶水解制备偃松仁蛋白肽,以产品的稳定性和感官评分作为考察指标,通过单因素实验及响应面优化试验确定偃松仁蛋白肽乳饮料的最佳工艺。结果表明:20%偃松仁蛋白水解液,2%乳粉,0.1%柠檬酸,6%绵白糖,0.2%复合稳定剂,均质次数4次/s,在此条件下产品的感官评价分为82分,离心沉降率为0.58%。其偃松松仁蛋白肽乳饮料色泽佳、组织均匀、乳脂香味适中,具有独特风味。     

Identification of bioactive peptides derived from caseins,glycosylation-dependent cell adhesion molecule-1 (GlyCAM-1), and peptidoglycan recognition protein-1 (PGRP-1) in fermented camel milk

Camel milk was fermented by Streptococcus thermophilus LMD-9 strain, the proteolytic system of which yielded peptides from the milk proteins. The peptides were isolated by cation-exchange chromatography and ultrafiltration, and then separated into 9 fractions by reversed-phase high-performance liquid chromatography. Two fractions displayed efficient radical-scavenging properties shown by Trolox equivalent antioxidant capacity assay. At least 347 peptides distributed in the different fractions were identified by tandem mass spectrometry. They mainly derived from the four different caseins, glycosylation-dependent cell adhesion molecule-1 (GlyCAM-1), also called lactophorin, and peptidoglycan recognition protein-1. For the first time, cleavage sites were identified for these six proteins and the susceptibility of GlyCAM-1 towards bacterial proteolysis directly in milk was shown. Investigation of peptide sequences homologous to known bioactive peptides highlighted not less than 16 different putative biological activities. Fermentation of camel milk was thus a means of food processing to produce potential bioactive peptides.     

Responses to amino acid imbalances and deficiencies in lactating dairy cows

Lactating cows were exposed to large amino acid imbalances and deficiencies by i.v. infusion to characterize responses in milk production and plasma concentrations of metabolites and hormones. Six cows in early lactation were fed a basal diet of 9% CP and infused continuously for 6 d with saline (negative control), 1.1 kg/d of a complete amino acid mix (positive control), or the equivalent mix lacking Met, Lys, His, or all 3 branched-chain amino acids. All cows received all treatments in 6 successive periods in a Latin square design. Infusion of the complete amino acid mix resulted in an increase in the plasma concentrations of several essential amino acids, insulin, and glucagon. Milk protein production was stimulated by 19%, which accounted for 10% of the infused amino acid. Plasma urea, acetate, and β-hydroxybutyrate concentrations were increased. Compared with saline, the amino acid mixtures lacking Met, Lys, or His increased essential amino acids, glucose, insulin, and glucagon concentrations in plasma, and decreased growth hormone. Plasma concentration of the essential amino acid absent from the infusate fell 2-fold but milk protein yield remained within 12% of its basal value. Dry matter intakes were depressed 35% over the first 2 d of infusion of imbalanced mixtures but recovered thereafter. Milk fat yields were increased 258 and 320 g/d by mixtures devoid of Lys and His, respectively. Correction of a Met, Lys, or His deficiency did not affect hormone concentrations in plasma and milk protein yield increased 27% due entirely to increased concentration of the single amino acid in plasma. Although imbalance and deficiency generated similar amino acid profiles in plasma, it was concluded that endocrine responses to total amino acid supply during imbalance can override imperfections in the circulating amino acid profile to maintain milk protein yield at higher levels than expected from deficiency states. Both imbalance and deficiency were characterized by a low protein:fat ratio in milk. Infusion of a mix of amino acids lacking Val, Ile, and Leu, despite a decrease in plasma Leu to 58% of its basal value, increased milk protein and fat yields to the same extent as the complete amino acid mix.     

Milk composition responses to unilateral arterial infusion of complete and histidine-lacking amino acid mixtures to the mammary glands of cows

To evaluate a close mammary infusion technique for the study of milk protein responses to blood amino acid profile, five early-lactation, multiparous Holstein cows were surgically fitted with catheters in both external iliac arteries. Animals were infused into one arterial catheter with five different solutions on 5 consecutive days in a Latin square design. Infusions began at 0800 h and continued until 1800 h. The five infusates were a 3% saline control, 15 g/h of complete amino acid mix, 15 g/h of imbalanced amino acid mix (minus His), 30 g/h of complete amino acid mix, and 30 g/h of imbalanced amino acid mix (minus His). Cows were fed a total mixed ration twice daily containing 16% crude protein and 1.7 Mcal/kg of net energy for lactation. Infusion of the complete amino acid mix elevated amino acid concentrations in arterial plasma two- to threefold but caused only a small dose-dependent increase in milk protein content and yield. Fat percentage in milk was decreased from 4.08 to 3.35% by the complete amino acid infusions so that the protein:fat ratio climbed from 0.76 on the control to 0.99 with 30 g/h of amino acid. Removal of His from the infusate caused plasma His concentrations to drop but had no effect on any other circulating amino acids. Milk composition was restored to control levels by removal of the single amino acid. A short-term circulating amino acid imbalance depresses milk protein percentage and increases milk fat content in dairy cows.     

Bioactive milk peptides: a prospectus

Bioactive peptides have been identified within the amino acid sequences of native milk proteins. Hydrolytic reactions, such as those catalyzed by digestive enzymes, result in their release. These peptides directly influence numerous biological processes evoking behavioral, gastrointestinal, hormonal, immunological, neurological, and nutritional responses. The specific bioreactions associated with each physiological class have been well characterized. Herein, we review the scientific literature and attempt to stimulate consideration of the continued use of bioactive peptides and their expanded development as a commercial product. Several applications have already evolved. For example, phosphopeptides derived from casein fractions are currently used as both dietary and pharmaceutical supplements. Potentially, the addition of bioactive peptides to food products could improve consumer safety as a result of their antimicrobial properties. Lastly, bioactive peptides may function as health care products, providing therapeutic value for either treatment of infection or prevention of disease.     

双菌种固态发酵豆粕生产大豆肽的研究

大豆肽是由大豆蛋白经水解所得到的由3～6个氨基酸残基组成的低分子肽混合物,分子量以低于1 000 Da的为主。以豆粕为原料,采用黑曲霉、米曲霉混合菌种固态发酵法生产大豆肽,制得的大豆肽具有较好的理化特性和生理活性,能去除抗营养因子,生产成本低,克服了酶解法产品苦味大和口感差等缺点。     

乳肉兼用型西门塔尔牛乳化学组成及营养评价

对西门塔尔牛乳的常规乳成分、氨基酸、脂肪酸组成以及主要矿物质质量分数进行测定,并对其进行营养评价与分析。结果表明,西门塔尔牛的脂肪质量分数,蛋白质质量分数均显著高于荷斯坦牛乳,多不饱和脂肪酸质量分数也高于荷斯坦牛乳,乳糖质量分数略低于后者。西门塔尔牛乳蛋白质中的必需氨基酸构成和联合国粮农组织/世界卫生组织(FAO/WHO)的推荐值十分相近。本研究为乳肉兼用型中国西门塔尔牛的推广提供了一定理论依据和参考价值。     

The Gel Filtration Chromatographic‐Profiles of Proteins and Peptides of Wort and Beer: Effects of Processing — Malting,Mashing, Kettle Boiling,Fermentation and Filtering

Barley and malt proteins, of infusion (IoB) and decoction (EBC) mashing worts as well as commercial wort and beer, obtained from the Castlemaine Perkins brewery, Brisbane, were gel filtered, with or without further treatments. A general, similar pattern of protein and peptide profiles emerged from barley malt and beer. This confirmed the widely assumed fact that beer proteins descend from barley, some transformed and others perhaps mostly unchanged by processing. In the gel‐filtrate profiles, a maximum of 8 or 9 fractions were discerned. These fractions were collected and quantified for protein contents and amino acid compositions. The first four fractions contained the proteins and polypeptides of molecular weight higher than 14,000. Consequently, the remaining fractions contain the smaller peptides (<14,000), that were completely removed by dialysis. The effects of processing on proteins and peptides varied contingent upon the type of processing step considered and the pre‐chromatographic treatment. Malting was the most effective process remarkably increasing the soluble protein contents, especially the smaller peptide fractions and the colour development. This is the first report, as far as we are aware of, on the gel filtration profiles of wort and beer low molecular weight peptides including those of barley wort. The importance of the smaller peptides in foam formation and retention cannot be overemphasised. The amino acid composition of the fractions revealed much more diversity than was observed in the comparison of the profiles. Proline content of fraction 1 resembled that of barley soluble proteins while fractions F2, F3 and F4 that of glutelin and only fraction 8 that of hordein. The latter, suggests that hordeins or, at least the peptide products rich in proline, are likely to be completely digested to amino acids, during malting.