秋刀鱼抗氧化肽制备及其抗氧化活性的研究

本文选择胰酶对秋刀鱼蛋白进行酶解,以蛋白质利用率和氧化自由基吸收能力(ORAC值)为指标,运用响应面分析法优化秋刀鱼蛋白制备抗氧化肽的酶解工艺,并且对酶解产物的特性进行了研究。结果表明:最优酶解条件为加酶量1085 U/g蛋白,水料比3:1,酶解时间8 h时,此时蛋白质利用率和ORAC值分别为76.86%和883.40μmol Trolox equivalent/g。秋刀鱼酶解产物的总氨基酸含量为4576.69 mg/100 mL,其中游离氨基酸和肽态氨基酸分别占34.28%和65.31%;总氨基酸中必需氨基酸占34.76%,抗氧化活性氨基酸和支链氨基酸占26.25%,说明秋刀鱼酶解产物具有较高的营养价值。秋刀鱼酶解产物中相对分子质量在1000~3000 Da之间的组分最多,占44.18%。秋刀鱼酶解产物清除DPPH·的IC50值为3.32 mg/mL,清除O2-·的IC50值为5.08 mg/mL,当秋刀鱼酶解产物的蛋白浓度为10 mg/mL时,其吸光值为0.67,说明秋刀鱼酶解产物具有较高的抗氧化活性。     

不同规格秋刀鱼肌肉的营养成分分析与品质评价

摘 要: 目的 对比分析不同规格秋刀鱼肌肉的营养价值。方法 参照国家标准方法测定大、中、小3种规格秋刀鱼肌肉的基本营养成分、脂肪酸组成和氨基酸组成, 比较其营养价值。结果 随着秋刀鱼规格的增大, 秋刀鱼肌肉中的粗脂肪含量增大, 而粗蛋白、水分含量减小; 3种规格秋刀鱼肌肉中均检测出18种氨基酸, 氨基酸总量为50.93~59.50 g/100 g, 且谷氨酸含量最高(7.00~8.39 g/100 g); 根据氨基酸评分,第一限制性氨基酸均为缬氨酸; 中规格秋刀鱼肌肉蛋白的必需氨基酸指数最高为88.44, 是良好蛋白源。不同规格秋刀鱼均富含多不饱和脂肪酸(47.23%~49.66%), 其中, 中规格秋刀鱼二十碳五烯酸和二十二碳六烯酸占总脂肪酸的比例最高为27.56%。结论 3种规格的秋刀鱼均属于高蛋白、高脂肪鱼类, 氨基酸和脂肪酸种类丰富且比例适中; 中规格秋刀鱼必需氨基酸指数最高, 二十碳五烯酸和二十二碳六烯酸的比例也最高, 营养价值相对较高。     

小麦蛋白酶解物分子量及氨基酸组成的研究

利用凝胶层析法对小麦蛋白酶解物分子量分布和氨基酸组成进行研究。结果表明:胃蛋白酶酶解物中多肽分子量在300～1 500Da的占52.4%,大于1 500Da的占18%,小于300Da的占29.5%;碱性蛋白酶酶解物中多肽分子量在300～1 500Da的占47.1%,大于1 500Da的占21.9%,小于300Da的占31.0%;必需氨基酸纯化后增加了6.7%,具有更好的营养价值。     

基于电子鼻技术的秋刀鱼新鲜度评价

采用德国PEN-3型便携式电子鼻收集4℃冷藏条件的秋刀鱼挥发性风味信息,并对收集的风味信息进行传感器载荷分析(loadings analysis)、线性判别分析(linear discriminant analysis,LDA)和主成分分析(principal component analysis,PCA),其结果与秋刀鱼感官评价、p H值、挥发性盐基氮(total volatile basic nitrogen,TVB-N)值和菌落总数等指标进行相关性分析。结果表明:秋刀鱼的气味随着贮藏时间的延长发生变化,其中氮氧化合物、有机硫化物和无机硫化物等电子鼻传感器的响应值变化最为明显;电子鼻分析结果与感官、p H值、TVB-N值和菌落总数分析结果显著相关,表明电子鼻检测技术可用作秋刀鱼新鲜度快速判别的一种新型检测方法。     

响应面法优化秋刀鱼酶解制备抗氧化活性肽的工艺

采用酶解法从秋刀鱼肌肉中提取抗氧化活性肽,以水解度(DH)、TCA-可溶性肽含量、DPPH自由基清除率、Fe3+还原力、·OH清除率以及O2?·清除率为指标,从六种商业用酶中(中性蛋白酶、碱性蛋白酶、风味蛋白酶、木瓜蛋白酶、菠萝蛋白酶、胰蛋白酶)筛选出最适蛋白酶.以料液比、酶添加量、酶解时间、温度、pH五个因素进行单因...     

云南不同产地臭灵丹草氨基酸测定及营养评价

目的以云南10个不同产地臭灵丹草为研究对象,测定其氨基酸组成及含量,对其营养价值进行评价,为臭灵丹草的资源利用及质量控制提供理论依据。方法采用氨基酸自动分析仪对氨基酸测定,利用氨基酸比值系数法和聚类分析法探讨不同产地臭灵丹草在氨基酸营养价值上的差异。结果各产地臭灵丹草中均含有17种氨基酸以及1种非蛋白类氨基酸γ-氨基丁酸,其中包括7种人体必需氨基酸,各产地臭灵丹草氨基酸总量为9.25%~19.74%,必需氨基酸含量为3.97%~8.63%,各产地臭灵丹草中氨基酸总量和必需氨基酸含量有明显差异,但各种氨基酸含量分布类似。臭灵丹草中氨基酸含量较高,且比例均衡,超过FAO/WHO提出的推荐值。臭灵丹草的氨基酸比值系数分(SRC)平均值为78.22,第一限制氨基酸为蛋氨酸+胱氨酸。臭灵丹草中含有丰富的药效氨基酸,占氨基酸总量的62.74%~66.48%。以氨基酸总量、必需氨基酸含量、药效氨基酸含量、必需氨基酸与氨基酸总量比值(E/T)、必需氨基酸与非必需氨基酸比值(E/N)、SRC值等为指标,聚类分析将各地臭灵丹草分为4类。结论臭灵丹草具有较高的营养价值和保健作用,有待成为新资源食品,可进一步开发利用。     

鲈鱼氨基酸酶水解液的制备和研究

介绍了以鲈鱼肉为原料,用酶水解方法制得复合氨基酸水解液的生产工艺,并对其营养成分、安全性进行了研究。结果表明,该水解液是一种良好的保健食品。     

鲈鱼氨基酸酶水解液的制备和研究

介绍了以鲈鱼肉为原料,用酶水解方法制得复合氨基酸水解液的生产工艺,并对其营养成分、安全性进行了研究。结果表明,该水解液是一种良好的保健食品。      

复合氨基酸亚铁的制备研究

本初步研究了利用脱脂豆粕酶解成复合氨基酸液，与亚铁盐螯合制备复合氨基酸的工艺，重点探讨了豆粕的酶解工艺和氨基酸亚铁的螯合反应条件。结果表明：豆粕酶解的最佳条件为加酶量(复合蛋白酶)为4％、固液比为1：24、pH值为8．0、酶解时间为16小时；复合氨基酸亚铁螯合的最佳条件为反应温度25℃，反应时间30min，pH=6．0，氨基酸与亚铁盐的配体摩尔比为2：1。     

近江牡蛎糖胺聚糖的酶解提取及其抗肿瘤活性研究

探讨酶解法提取近江牡蛎糖胺聚糖(SG1)的务件,结果表明:先用枯草杆菌中性蛋白酶1.0%(质量分数),pH7.0,50℃酶解5 h,再加胰蛋白酶1.0%(质量分数),pH7.8,50℃酶解5 h效果最佳.粗提物SG1的得率为2.40%,总糖胺聚糖含量为13.6%,总糖含量为61.3%.采用四氮唑蓝还原法(MTT法)研究粗提物SG1对人宫颈癌细胞(Hela细胞)的体外抗肿瘤活性,结果显示:500μg/mL剂量组与600μg/mL剂量组48h时的抑制率分别为43.1%(P<0.05),55.8%(P<0.05),近江牡蛎糖胺聚糖粗提物SG1具有较明显的抗肿瘤活性,存在一定的量效关系.     

AMINO ACID ANALYSIS OF BEER POLYPEPTIDES

The principles of amino acid analysis of proteins and polypeptides are reviewed. Analysis of the amino acid composition of dialysed beer material prepared from a wide variety of commercial and pilot brewery beers showed that the principal amino acids comprised glutamic acid/glutamine, proline, glycine and aspartic acid/asparagine. The results from the analysis of a series of pilot brewery beers brewed under standardised conditions showed that the composition of the grist may influence the amino acid composition of beer polypeptide fractions. Dialysed beer material prepared from beer brewed from grists containing torrified wheat, wheat flour and malted wheat contained greater proportions of glutamic acid/glutamine compared to material prepared from all malt beers. Further fractionation and analysis of dialysed beer material prepared from pilot brewery beers suggested that fractions MW>60000 contained polypeptide material derived from yeast mannan-protein. In addition fractions MW>60000 prepared from beer brewed from grists containing torrified wheat, wheat flour or all malted wheat may contain high molecular weight polypeptide material derived from wheat proteins. The results from the analysis of fraction MW 40,000–60000 prepared from beers brewed from grists containing all malt, 80% malt and 20% torrified wheat and 50% malt and 50% malted wheat are consistent with the presence of polypeptide material derived from cereal albumins and globulins whereas fractions MW 40,000–60000 prepared from beers brewed from 80% malt and 20% wheat flour and 100% malted wheat may contain polypeptide material derived from wheat prolamins and glutelins. The amino acid composition of fraction MW 20,000–40,000 from all pilot brewery beers investigated is consistent with the presence of polypeptide material derived from cereal prolamins and glutelins. The amino acid composition of beer polypeptide fractions may be used to detect the use of wheat adjuncts in beer brewing.     

新疆一枝蒿氨基酸的高效液相色谱分析

利用高效液相色谱法测定新疆一枝蒿枝及花中17种氨基酸含量，结果表明：新疆一枝蒿枝及花中含有多种氨基酸，氨基酸总含量分别达到1．3856％和3．5522％，可用于开发保健饮品。     

RATE-LIMITING ENZYMES IN THE LIBERATION OF AMINO ACIDS IN MASHING

When 29 malts representing a wide variation in free amino nitrogen of wort were mashed for 3 h at 45°C, the increases in TCA-soluble amino nitrogen varied from 47 to 116 μmoles per gramme of malt. The carboxypeptidase activities of the malts showed only small positive correlations with the increase of amino nitrogen during mashing. Inactivation of the different malt carboxypeptidases by 70 to 90% with diisopropylfluorophosphate decreased the liberation of amino nitrogen by only 5 to 25%. Moreover, addition of purified malt carboxypeptidase I to the mashing suspensions had no effect on the liberation of amino nitrogen. It is therefore evident that the carboxypeptidases do not have a major rate-limiting role in the liberation of amino acids in mashing, although it has earlier been shown that they are essential enzymes in this process. The proteinase activities of the malts, determined using two methods, correlated strongly with the liberation of amino nitrogen in mashing. Addition of crude malt proteinase to the mash increased, and addition of purified barley proteinase inhibitor decreased the measured proteinase activity and the liberation of amino acids roughly to the same extent. These results indicate that the most important rate-limiting enzyme activity in the liberation of amino acids in mashing is the proteinase activity of the malt.     

THE MARGARET JONES MEMORIAL LECTURE AMINO ACIDS IN MALTING AND BREWING

Margaret Jones' researches into the role of amino acids in the biochemistry of malting and brewing are reviewed.     

PREPARATION OF TRANS-ISO-ALPHA ACIDS AND USE OF THEIR DICYCLOHEXYLAMINE SALTS AS A STANDARD FOR ISO-ALPHA ACIDS ANALYSIS

The reaction between dicyclohexylamine and iso-alpha acids yields a crystalline product which consists of the dicyclohexylamine salts of trans-iso-cohumulone, trans-isohumulone and trans-iso-adhumulone. The presence of only the trans-isomers in the crystalline product was established by proton and carbon NMR. Pure trans-iso-alpha acids can be regenerated from the salt either by treatment with acid or in situ by the use of acidic buffers during HPLC analysis. The dicyclohexylamine salts of the trans-iso-alpha acids are stable for extended periods at room temperature, unlike the purified trans-iso-alpha acids, and are thus suitable for use as a standard for iso-alpha acids analysis.     

THE DETERMINATION OF AMINO ACIDS IN WORT,BEER AND BREWING MATERIALS USING GAS CHROMATOGRAPHY

Various methods for the separation of amino acids from brewing materials and subsequent analysis by gas chromatography have been examined. Separation of the amino acids by ion exchange chromatography followed by derivatization and gas chromatography of the trifluoracetyl n-butyl or heptafluorobutyl iso-amyl esters proved the most satisfactory methods to employ.     

ANALYSIS OF BIOGENIC AMINES AND THEIR PRECURSOR FREE AMINO ACIDS IN MAHI-MAHI (CORYPHAENA HIPPURUS)

Fish is a rich source of free amino acids, and provides a good medium for microbial growth. Deterioration offish quality is often determined by chemical indicators of microbial activity such as biogenic amines. This study investigated the possible correlations between the levels of biogenic amines and their precursor free amino acids. Two groups of mahi‐mahi fillets were stored at 7C and sampled on days 0, 2, 4, 6, 8 and 10 for amino adds and biogenic amines. One group was dipped in an inoculum of Morganella morganii (10⁵ CFU/mL) while the other group was not inoculated. Except for histamine, levels of the analytes were similar in both groups of fish. Histamine and putrescine poorly correlated with histidine (r = ‐0.42) and ornithine (r = ‐0.27), respectively. Cadaverine correlated with lysine (r = 0.61), histamine (0.78), and putrescine (r = 0.85), and reached 3 mg/100 g on day 3. Cadaverine can serve as a good indicator of incipient and late spoilage in chilled mahi‐mahi.