High Temperature During Rice Grain Filling Enhances Aspartate Metabolism in Grains and Results in Accumulation of AspartateFamily Amino Acids and Protein Components

Global warming causes the exacerbation of rice growing environment, which seriously affects rice growth and reproduction, and finally results in the decrease of rice yield and quality. We investigated the activities of aspartate metabolism enzymes in grains, and the contents of Aspartate-family amino acids and protein components to further understand the effects of high temperature （HT） on rice nutritional quality during rice grain filling. Under HT, the average activities of aspartate aminotransferase （AAT） and aspartokinase （AK） in grains significantly increased, the amino acid contents of aspartate （Asp）, lysine （Lys）, threonine （Thr）, methionine （Met） and isoleucine （lie） and the protein contents of albumin, globulin, prolamin and glutelin also significantly increased. The results indicated that HT enhanced Asp metabolism during rice grain filling and the enhancement of Asp metabolism might play an important role in the increase of Asp-family amino acids and protein components in grains. In case of the partial appraisal of the change of Asp-family amino acids and protein components under HT, we introduced eight indicators （amino acid or protein content, ratio of amino acid or protein, amino acid or protein content per grain and amino acid or protein content per panicle） to estimate the effects of HT. It is suggested that HT during rice grain filling was benefit for the accumulation of Asp-family amino acids and protein components. Combined with the improvement of Asp-family amino acid ratio in grains under HT, it is suggested that HT during grain filling may improve the rice nutritional quality. However, the yields of parts of Asp-family amino acids and protein components were decreased under HT during rice grain filling.

Effect of High Digestible Essential Amino Acids on Weight Gains and Carcass Compositions of Laying Hens

The objective of this study was to evaluate the effect of high digestible essential amino acids （DEAA） on weight gains and carcass compositions of laying hens. Three hundred and sixty lsa Brown hens in five replications per treatment （12 birds/replicate） were used. Six experimental diets which contained of treatment 1 （negative control） as the conventional layer diet are recommended by NRC （1994） while another dietary treatments; treatments 2 （positive control）, 3, 4, 5 and 6 were formulated to meet 100%, 110%, 120%, 130% and 140% of Standard Ileal Digestible Lysine Levels （SIDLL） without crude protein minimum, while methionine （Met）, threonine （Thre） and tryptophan （Tryp） as related by Ideal Protein Concept （IPC） which suggested by NRC （1994） and INRA （2004）. However, metabolizable energy （ME）, calcium and available phosphorus （Avai P） levels of all experimental diets were meet requirement as recommended by NRC （1994）. The experiment was assigned in CRD and laying hens fed dietary treatments from 28 to 44 weeks of age and cage was the experimental unit （3 hens/cage）. The result shown that percentages of thigh （TP）, feet （FP）, drumstick （DP）, heart （HP）, liver （LP） and gizzard （GP） were not affected by dietary treatment. However, weight gains （WG） and percentage of dressed weight （DWP）, eviscerate weight （EWP） and breast （BP） were increased （P 〈 0.05） and abdominal fat was reduced （P 〈 0.05） when birds fad diets containing 130% of SIDLL as compared with control group and another dietary treatments, when increasing the DEAA levels upper to 130% of SIDLL. The result indicated that diets formulated without crude protein minimum and increased DEAA resulted in increasing the efficiency of converting metabolizable energy （ME） to net energy （NE） for increasing weight gain and improved meat products while fat deposition in carcass composition was reduced.

Expression of L amino acid transport system 1 and analysis of iodine-123-methyltyrosine tumor uptake in a pancreatic xenotransplantation model using fused high-resolution-micro-SPECT-MRI

BACKGROUND:The specificity in discriminating pancreatitis is limited in the positron emission tomography(PET)using Fluorine-18-fluorodeoxyglucose.Furthermore,PET is not widely available compared to the single photon emission computed tomography(SPECT).Since amino acids play a minor role in metabolism of inflammatory cells,the potential of the SPECT tracer,3-[ 123 I]iodo-L-α-methyltyrosine(123I-IMT),for detecting pancreatic cancer was examined in xenotransplantation models of human pancreatic carcinoma in mice. METHODS: 123 I-IMT was injected to eight mice inoculated with subcutaneous or orthotopic pancreatic tumors.Fused high-resolution-micro-SPECT(Hi-SPECT)and magnetic resonance imaging were performed.The gene expression level of L amino acid transport-system 1(LAT1)was analyzed and correlated with tumor uptake of 123 I-IMT. RESULTS:A high uptake of 123 I-IMT was detected in all tumor-bearing mice.The median tumor-to-background ratio (T/B)was 12.1(2.0-13.2)for orthotopic and 8.4(1.8-11.1)for subcutaneous xenotransplantation,respectively.Accordingly, the LAT1 expression in transplanted Colo357 cells was increased compared to non-malignant controls.CONCLUSIONS:Our mouse model could show a high 123 I-IMT uptake in pancreatic cancer.Fused MRI scans facilitate precise evaluation of uptake in the specific regions of interest.Further studies are required to confirm these findings in tumors derived from other human pancreatic cancer cells.Since amino acids play a minor role in the metabolism of inflammatory cells,the potential for application of 123 I-IMT to distinguish pancreatic tumor from inflammatory pancreatitis warrants further investigation.

OPTICALLY ACTIVE AMINO ACIDS WITH HIGHLY BRANCHED SIDE CHAIN (I) SYNTHESIS OF D- AND L- 2-AMINO-5,5-DIMETHYLHEXANOIC ACID AND 2-AMINO-6,6-DIMETHYLHEPTANOIC ACID

The title compounds were prepared by the enzymatic resolution of the corresponding N-acetylated DL-amino acids methyl esters, which were obtained from t-butyl chloride via an 8-step synthesis.

Analysis of Amino Acids in Houttuynia Cordata Thunb. by High Performance Liquid Chromatography-Diode Array Detector (HPLC-DAD)

[Objectives] The biologically active compounds of Houttuynia cordata Thunb. as a medicinal and edible plant are well documented. However, amino acid as an important indicator of the value of H. cordata is little reported. [Methods] Amino acids of the H. cordata were analysed by pre-column derivatization with 2,4-dinitrochlorobenzne(CDNB) coupled to HPLC/DAD. The optimized conditions of the amino acids derivatized by CDNB were followed: 110 ℃ of hydrolysis temperature, 1∶12 of the equivalent proportion between amino acid and CDNB, 80 min of derivatization reaction time and 80 ℃ of derivatization reaction temperature. The method was used to determine the amino acids of H. cordata samples from 11 different geographical sites in Guizhou. [Results] The results suggested that the contents of 17 amino acids were quite variable at different H. cordata samples. [Conclusions] This study will provide a basis for the quality evaluation of H. cordata nutrition.

Differences in the Content of Protein and Essential Amino Acids between Different Rice Varieties

Evaluation of the protein content is a major indicator of the nutritional quality of rice,and the protein quality of rice is the best among cereal crops. Essential amino acids play an irreplaceable role in human growth,development and health care. Essential amino acid is a key ingredient to measure the nutritional value of rice. Using the experimental rice processed from the rice variety " Yuzhenxiang" sprayed with plant nutrients( patent number: ZL201110103910. 9),namely high essential amino acid nutritional rice,combined with five kinds of high quality rice imported by COFCO and homegrown " Wuchang rice",we send the samples of the seven kinds of rice to Hunan Food Testing Center,and adopt HPLC method to test the content of protein and eight kinds of essential amino acids. Three bags of rice are randomly selected for each kind of rice,and each bag is a replication. The test results show that there are highly significant differences in the content of essential amino acids between different kinds of rice( F = 246. 29**,P =5 ×10- 71),and there are also highly significant differences in the content between different kinds of essential amino acids( F = 3937. 09**,P = 4 × 10- 146). The test results of protein content indicate that there are highly significant differences in the content of protein between different kinds of rice( F = 3937. 0973. 29**,P =5. 81 ×10- 11),and the test results of lysine content show that there are highly significant differences in the content of lysine between different kinds of rice( F =3937. 0973. 29**,P =5. 81 ×10- 11).

Metabolic profile analysis of free amino acids in experimental autoimmune uveoretinitis rat plasma

AIM: To determine the differences of amino acid(AA) levels in experimental autoimmune uveoretinitis(EAU). METHODS: AA analysis of the plasma samples in EAU rats induced by interphotoreceptor retinoid-binding protein emulsion were performed with high performance liquid chromatography(HPLC) and phenylisothiocyanate(PITC) pre-column derivation methods were performed. Using partial least squares discriminant analysis(PLS-DA), the potential biomarkers were identified in EAU rat plasma, and the metabolic pathways related to EAU were further analyzed. RESULTS: The method results showed that linear(r≥0.9957), intra-day reproducible [relative standard deviation(RSD)=0.04%-1.33%], inter-day reproducible(RSD=0.06%-2.07%), repeatability(RSD=0.03%-0.89%), stability(RSD=0.05%-2.48%) and recovery(RSD=1.98%-4.39%), with detection limits of 0.853-11.4 ng/mL. The metabolic profile in EAU rats was different from that in the control groups five AAs concentrations were increased and nine AAs were reduced. Moreover, five metabolic pathways were related to the development of EAU. CONCLUSION: The developed method is a simple, rapid and convenient for determination of AAs in EAU rat plasma, and these findings will provide a comprehensiveinsight on the metabolic profiling of the pathological changes in EAU.

Effect of borneol, moschus, storax, and acorus tatarinowii on expression levels of four amino acid neurotransmitters in the rat corpus striatum

The present study collected cerebrospinal fluid samples from the corpus striatum in rats treated with borneol, moschus, storax, and acorus tatarinowii using brain microdialysis technology. Levels of excitatory neurotransmitters aspartic acid and glutamate, as well as inhibitory neurotransmitters glycine and ^-aminobutyric acid, were measured in samples using reversed-phase high-performance liquid chromatography, phosphate gradient elution, and fluorescence detection. Results showed that concentrations of all four amino acid neurotransmitters significantly increased in the corpus striatum following treatment with borneol or moschus, but effects due to borneol were more significant than moschus. Acorus tatarinowii treatment increased ^-aminobutyric acid expression, but decreased glutamate concentrations. Storax increased aspartic acid concentrations and decreased glycine expression. Results demonstrated that borneol and moschus exhibited significant effects on con amino acid neurotransmitter expression; storax exhibited excitatory effects and acorus tatarinowii resulted in inhibitory effects.

Determination of 18 Kinds of Amino Acids in Fresh Tea Leaves by HPLC Coupled with Pre-column Derivatization

A rapid and accurate quantitative method of high performance liquid chromatography( HPLC) with fluorescence detector has been developed for the analysis of 18 kinds of amino acids in fresh tea leaves. The samples were minced and mixed,and extracted with ultra pure water at 90℃ for 20 min. The 6-aminoquinolyl N-hydroxy-succinimidyl carbamate( AQC) was used as pre-column derivatization reagent. Gradient HPLC separation was performed on a C_(18) column( Symmetry C_(18),3. 9 mm × 15 cm,4 μm). Good linearity between concentrations and peak areas was achieved in the concentration range of 5. 0-250 μmol/L for 18 kinds of amino acids. The method was validated by the analysis of five replicates. The 18 kinds of amino acid standards were spiked in fresh tea leaf samples and the average recovery rate was 86. 25%-109. 05% with relative standard deviations( n = 5) ranging from 6. 03% to 10. 56%. The limit of detection( LOD) for the analytes was0. 05-1. 27 μmol/L. The method was successfully applied to the analysis of the 18 kinds of amino acids in fresh tea leaves from east Dongting and west Dongting mountains in Suzhou. The results indicate that the method is simple,rapid,precise and reliable.

Com parison of Amino Acids in Root Exudates of Flue-cured Tobacco Varieties with Different Resistances against Black Shank

In order to explore the differences of amino acids in root exudates and plant tissues, we selected four flue-cured tobacco varieties [ Yunyan 87 （ Ⅰ）, K326 （Ⅱ）, NC102（Ⅲ）, Hongda （Ⅳ）] as the test materials and studied the components and mass fractions of amino acids in rhizosphere soil, non rhizosphere soil, roots and leaves via high performance capillary zone electrophoresis. Ten amino acids were detected out from four varieties, including histidine, lysine, tryptophan, phenylalanine, valine, threonine, proline, serine, alanine and glycine. The mass fractions of amino acids in leaves and roots were higher than those in rhizosphere soil and non rhizosphere soil. In rhizosphere soil and non-rhizosphere soil, the mass fractions of lysine, phenylalanine, threonine, proline and glycine in susceptible varieties （ Ⅲ, Ⅳ） were higher than those in resistant varieties （ Ⅰ, Ⅱ）. In rhizosphere soil, the total amino acids successively were Ⅳ 〉 Ⅲ 〉 Ⅰ 〉 Ⅱ, and in non rhi- zosphere soil were Ⅲ 〉 Ⅳ 〉 Ⅰ 〉 Ⅱ. The total amino acids in roots of variety Ⅳ was the highest, up to 6 359. 195 μg/g. In leaves, the total amino acids in varieties I and If were higher than those in varieties IfI and IV. The results indicated that amino acids could secrete to rhizosphere via root secretion, and the compositions and mass fractions of amino acids varied with flue-cured tobacco varieties, thus the secretion amount of susceptible varieties was higher than that of resistant varieties.

青海高原栽培羊肚菌营养和氨基酸特征分析及综合评价

为探究高原地区栽培羊肚菌(Morchella spp.)的营养品质,以海拔3 570 m栽培的3个六妹羊肚菌(M. sextelata)品种(M6、HB-8和HB-5)子实体(高原栽培羊肚菌)为主,对比同地域野生样品及湖北栽培的相同品种样品(平原栽培羊肚菌),分析粗蛋白、粗脂肪、粗多糖、灰分、粗纤维、矿质元素、维生素和氨基酸等营养成分的差异。结果显示:当品种相同时,与平原栽培羊肚菌相比,高原栽培羊肚菌的粗蛋白、粗脂肪含量显著上升,灰分含量显著下降,粗纤维含量显著降低(除M6外);K和Fe含量均显著降低;维生素B6、维生素B2、维生素B9、维生素D、维生素E含量显著降低,维生素B1含量显著升高;总氨基酸含量、总必需氨基酸含量及总必需氨基酸占总氨基酸含量均显著上升。高原栽培羊肚菌的必需氨基酸指数(IAAI)明显高于平原栽培羊肚菌,更接近于FAO/WHO标准蛋白,且其生物价(BV)更高。关联性分析表明,羊肚菌中维生素B6、维生素B9(叶酸)、维生素D和维生素E含量与总必需氨基酸含量呈极显著负相关,维生素B6与粗多糖含量存在显著正相关。热图-聚类分析结果表明,高原栽培羊肚菌蛋白营养价值突出,而平原栽培羊肚菌矿质元素含量较高。营养品质综合评价结果表明,高原栽培羊肚菌样品评分结果明显均优于相同品种的平原栽培样品。

Excitatory amino acid changes in the brains of rhesus monkeys following selective cerebral deep hypothermia and blood flow occlusion

Selective cerebral deep hypothermia and blood flow occlusion can enhance brain tolerance to ischemia and hypoxia and reduce cardiopulmonary complications in monkeys. Excitotoxicity induced by the release of a large amount of excitatory amino acids after cerebral ischemia is the major mechanism underlying ischemic brain injury and nerve cell death. In the present study, we used selective cerebral deep hypothermia and blood flow occlusion to block the bilateral common carotid arteries and/or bilateral vertebral arteries in rhesus monkey, followed by reperfusion using Ringer＇s solution at 4~C. Microdialysis and transmission electron microscope results showed that selective cerebral deep hypothermia and blood flow occlusion inhibited the release of glutamic acid into the extracellular fluid in the brain frontal lobe and relieved pathological injury in terms of the ultrastructure of brain tissues after severe cerebral ischemia. These findings indicate that cerebral deep hypothermia and blood flow occlusion can inhibit cytotoxic effects and attenuate ischemic/ hypoxic brain injury through decreasing the release of excitatory amino acids, such as glutamic acid.

柱前衍生-高效液相色谱法测定巴戟天中氨基酸含量及营养价值评价

建立柱前衍生-高效液相色谱法测定巴戟天中氨基酸含量,采用氨基酸比值系数法评价其营养价值。采用盐酸水解法制得巴戟天氨基酸供试品溶液,以异硫氰酸苯酯和三乙胺为柱前衍生化试剂,采用高效液相色谱法,使用Ultimate Amino Acid色谱柱(4.6 mm×250 mm,5μm)以0.1 mol/L无水乙酸钠-乙腈为流动相,梯度洗脱,柱温40℃,检测波长为254 nm,测定氨基酸含量;通过氨基酸比值、氨基酸比值系数、氨基酸比值系数分等评价其营养价值,并采用系统聚类和主成分分析对其进行分类分析。结果表明,15种氨基酸线性关系良好,相关系数r≥0.9996。16份巴戟天氨基酸总含量为17.87~102.15 mg/g,均检测到15种氨基酸,其中包含6种必需氨基酸,占总氨基酸含量的14.15%~32.06%;8种药用氨基酸,占总氨基酸含量的45.20%~56.31%。限制氨基酸为苏氨酸和亮氨酸,氨基酸比值系数分为33.87~61.31。不同巴戟天样品氨基酸组成相关性显著;主成分分析提取2个主成分,累计方差贡献率为97.085%,可将16批巴戟天分为三类。该实验测定方法简单有效,可同时分离测定15种氨基酸,精密度与重复性良好,有较高的药用价值,可为巴戟天的品质分析和资源开发利用提供参考。

高效液相色谱-紫外检测法同时测定洗面奶中4种N-月桂酰氨基酸表面活性剂

N-月桂酰氨基酸(NLAAs)表面活性剂与传统表面活性剂相比在安全性上具有明显的优势,应用领域日益增多。但由于NLAAs的紫外吸收较弱,采用高效液相色谱-紫外检测进行含量测定存在一定困难,一般使用示差折光指数检测器、蒸发光散射检测器等通用型检测器来进行检测。为解决这一难题,本研究通过优化流动相的组成,选择合适的色谱柱和检测波长,建立了高效液相色谱-紫外检测同时测定月桂酰谷氨酸(LG)、月桂酰甘氨酸(LC)、月桂酰丙氨酸(LA)、月桂酰肌氨酸(LS)4种NLAAs表面活性剂的方法。样品在乙腈-0.10%H_(3)PO_(4)水溶液(60∶40,v/v)中超声提取10 min,滤膜过滤后用高效液相色谱仪测定,以乙腈-0.10%H_(3)PO_(4)水溶液为流动相进行梯度洗脱,经Agilent Eclipse Plus C_(18)色谱柱(150 mm×4.6 mm,5μm)分离,在205 nm波长处进行检测。结果显示:4种NLAAs在2.0~800.0 mg/L范围内呈良好的线性关系,相关系数(r)均≥0.9995,检出限(LOD)为0.17~0.49 mg/L,定量限(LOQ)为0.57~1.63 mg/L。在0.60、4.50、15.00、24.00 mg/g 4个加标水平下,NLAAs的加标回收率在94.3%~107.4%范围内。采用该方法对5个洗面奶样品中的NLAAs进行含量测定,发现所有样品都含有一种或多种NLAAs化合物,NLAAs的总含量在64.58~97.01 mg/g范围内。该方法前处理简单,测试快速,方法精密度、准确性、稳定性良好,适于洗面奶中NLAAs的含量测定,也可为该类型表面活性剂原料纯度、合成产率检测及产品的质量控制提供有效的技术参考。

柱前衍生-高效液相色谱法测定化妆品中16种氨基酸的含量

提出了2,4-二硝基氟苯(DNFB)柱前衍生-高效液相色谱法测定化妆品中甘氨酸、亮氨酸、组氨酸、缬氨酸、甲硫氨酸、脯氨酸、半胱氨酸、苏氨酸、谷氨酸、赖氨酸、酪氨酸、精氨酸、异亮氨酸、色氨酸、苯丙氨酸、丙氨酸等16种氨基酸含量的方法。取化妆品样品5 g置于50 mL离心管中,加入5 mL水,超声10 min,加热煮沸15 min,冷却后加入15 mL 35 g·L^(−1)磺基水杨酸溶液,以转速10500 r·min^(−1)离心20 min。取全部上清液,用35 g·L^(−1)磺基水杨酸溶液定容至25 mL。取1 mL样品溶液,加入0.5 mol·L^(−1)碳酸氢钠溶液(pH 9.0)1 mL和1%(体积分数)DNFB衍生溶液1 mL,混匀,于60℃加热10 min,冷却后用0.01 mol·L^(−1)磷酸二氢钾溶液(pH 7.0)定容至5 mL,所得溶液中16种氨基酸经X Bridge C_(18)色谱柱分离,以不同体积比的含1%(体积分数)N,N-二甲基甲酰胺的0.05 mol·L^(−1)乙酸钠缓冲液(pH 6.5)-体积比1∶1的乙腈-水混合溶液为流动相进行梯度洗脱,在360 nm处检测。结果表明:16种氨基酸标准曲线的线性范围均为0.004~40.0 mg·L^(−1),检出限(3S/N)为0.1~0.2 mg·kg^(−1);对空白样品进行3个浓度水平的加标回收试验,回收率为89.0%~105%,测定值的相对标准偏差(n=7)均不大于10%。方法用于11种市售化妆品分析,检出的氨基酸成分多为组氨酸、甘氨酸、甲硫氨酸、谷氨酸。

氨基酸配方替代喂养对重度牛奶蛋白过敏婴儿肠道菌群特征的影响

目的探讨氨基酸配方(AAF)替代喂养对重度牛奶蛋白过敏(CMPA)婴儿肠道菌群特征的影响。方法纳入23例确诊为重度CMPA且人工喂养的≤3月龄婴儿,采用同一品牌AAF进行喂养干预。干预前及干预3个月后,收集所有婴儿的粪便样本,通过16S rRNA高通量测序及生物信息学分析评估肠道菌群的特征变化。结果干预前后,重度CMPA婴儿肠道菌群Chao1指数、Shannon指数、observed species指数、Simpson指数差异具有统计学意义(P<0.05),Beta多样性具有差异,且组间差异大于组内差异。门水平的相对丰度分析及LEfSe分析结果均显示,AAF干预后重度CMPA婴儿肠道中厚壁菌门、拟杆菌门显著富集。属水平的相对丰度分析结果显示,AAF干预后重度CMPA婴儿肠道中拟杆菌属、粪杆菌属、双歧杆菌属的相对丰度较干预前明显升高,弓形菌属、克雷伯菌属、梭菌属的相对丰度较干预前降低,LEfSe分析结果显示拟杆菌属、粪杆菌属、弓形菌属、克雷伯菌属为在丰度上有显著差异的标志物种。在种水平上相对丰度排名前10的菌群中,产气荚膜梭菌、产酸拟杆菌、丁酸梭菌、格氏乳杆菌、罗伊氏乳杆菌的相对丰度显著升高。结论AAF替代喂养可使得重度CMPA患儿肠道菌群多样性增加,拟杆菌、厚壁菌等的丰度增加。

湖南石门县地方品种鸡肉氨基酸组成分析及蛋白质营养价值评价

目的探究湖南省石门当地7个品种鸡肉中的基本营养成分及氨基酸组成差异,并对其进行蛋白质营养价值评价。方法采用相关国家标准测定7个品种鸡肉中水分、粗灰分、粗脂肪、粗蛋白含量,并利用高效液相色谱仪对鸡肉氨基酸含量进行测定,基于联合国粮食及农业组织和世界卫生组织(Foodand Agriculture Organization/World Health Organization,FAO/WHO)标准模式谱对不同品种鸡胸肉和腿肉蛋白质分别进行营养学评价。结果7个品种鸡胸肉、腿肉中水分含量分别为71.20~74.97 g/100 g、72.65~76.22 g/100 g,粗灰分含量分别为0.90~1.38 g/100 g、0.91~1.28 g/100 g,粗脂肪含量分别为0.15~0.64 g/100 g、2.30~7.74 g/100 g,粗蛋白质含量分别为22.29~24.61 g/100 g、19.00~21.80 g/100 g,不同品种、部位间存在差异。7个品种鸡肉均检测出17种氨基酸,均以谷氨酸含量为最高;胸肉氨基酸含量高于腿肉(除壶瓶山鸡),其中青脚鸡胸肉和壶瓶山鸡腿肉的总氨基酸含量最高。7个品种鸡肉必需氨基酸与总氨基酸的比值与FAO/WHO推荐的理想蛋白质模式较为接近;其中苏氨酸、异亮氨酸、亮氨酸、苯丙氨酸+酪氨酸、赖氨酸占总氨基酸的质量分数均明显高于FAO/WHO推荐的模式谱标准值;除麻鸡胸肉、青脚鸡腿肉外,其余鸡种胸肌和腿肌氨基酸比值系数分均能达70以上。结论7个品种鸡肉中蛋白质与FAO/WHO规定的人体蛋白需求相类似,蛋白质营养价值较高,本研究结果以期为树立石门当地肉鸡口碑、进一步选育和开发利用新鸡种提供科学依据。

市售鱼鳔氨基酸及蛋白质成分分析

目的 分析16批不同基原的市售鱼鳔中氨基酸及蛋白质成分。方法 建立一种6-氨基喹啉基-N-羟基琥珀酰亚胺基甲酸酯柱前衍生、高效液相色谱法,测定鱼鳔中17种氨基酸含量,并对不同基原鱼鳔中氨基酸类成分进行分析;采用十二烷基硫酸钠聚丙烯酰胺凝胶电泳分析鱼鳔中的蛋白质分子量分布,并采用蛋白质组学法鉴定鱼鳔中的蛋白质。结果 17种氨基酸在一定浓度范围内线性关系良好(R2≥0.998 0),平均加样回收率85.62%~109.60%,精密度、稳定性、重复性RSD均小于3.5%。16批鱼鳔氨基酸组成与含量存在差异,氨基酸总含量介于468.31~620.05 mg/g;从16批鱼鳔中共鉴定688种蛋白质,包括Ⅰ型在内的胶原蛋白多达11种,此外,鱼鳔中还含有较多分子质量52~95 kDa的低丰度蛋白。结论 该研究可为鱼鳔的质量评价和开发利用提供参考。

排酸方式和时间对高档育肥安格斯牛肉品质的影响

为探究高档牛肉的排酸技术,本研究选取12条高档育肥安格斯牛背最长肌肉为原料,通过干式和湿式排酸,选择3、5和7 d三个时间点,并对牛肉基本理化指标、游离氨基酸和挥发性风味物质综合分析。结果显示,干式排酸3和5 d牛肉pH显著低于湿式排酸,干式排酸7 d牛肉pH显著高于湿式排酸(P<0.05);干式排酸3 d牛肉剪切力显著低于湿式排酸(P<0.05)。干式和湿式排酸7 d牛肉中丝氨酸、缬氨酸、蛋氨酸、异亮氨酸、酪氨酸、亮氨酸、苯丙氨酸、精氨酸、赖氨酸、甜味氨基酸、苦味氨基酸及总游离氨基酸的含量均显著提高(P<0.05);干式排酸7 d牛肉中天冬氨酸、谷氨酸、丙氨酸和鲜味氨基酸的含量显著高于湿式排酸(P<0.05)。干式排酸和湿式排酸最主要的挥发性风味贡献物质均为壬醛、正辛醛和1-辛烯-3-醇;湿式排酸特有的挥发性风味物质为庚醛,干式排酸7 d牛肉中正辛醛、苯乙醛、十一醛、肉豆蔻醛和柠檬烯相对含量显著高于湿式排酸(P<0.05)。综上所述,排酸7 d有利于提升高档育肥安格斯牛肉风味的丰富度,干式排酸较湿式排酸对高档牛肉风味改善作用更佳。

超高温瞬时灭菌对米酒品质的影响

目的:使经过超高温瞬时灭菌的米酒既符合商业上无菌要求也满足消费者对米酒质量的要求。方法:对朝鲜族米酒进行超高温瞬时灭菌,在贮藏期每周测定其理化指标、感官指标以及微生物指标以确定该灭菌法的最佳灭菌条件,并分析此灭菌方法处理的朝鲜族米酒在贮存20周后的品质和功能性成分的变化。结果:超高温瞬时灭菌的最佳参数为125℃灭菌5 s。贮存20周后,米酒中总氨基酸含量为0.70 mg/100 mL,有机酸含量为321.68 mg/100 mL。结论:超高温瞬时灭菌方法对氨基酸含量有一定负面影响,但能在保证米酒风味的同时高效灭菌。