Effects of High-intensity Pulsed Electric Field on Amino Acid Content in Large-leaf Pu'er Tea Variety

[Objective] This study aimed to test the effects of high-intensity pulsed electric field on the amino acid content in Pu’er tea leaves. [Method] The amino acid contents of fermented and unfermented the leaves of large-leaf Pu’er tea variety produced in Yunnan Mengku, were measured before and after the treatment with high-intensity pulsed electric field （HPEF）. [Result] The difference of amino acid contents was notable between fermented and unfermented tea leaves produced in the same year. The amino acid content of unfermented tea leaves was larger than that in fermented tea leaves. The amino acid content in tea leaves decreased over time during storage. HPEF treatment under al the conditions improved the amino acid content in tea leaves. [Conclusion] This experiment provides theoretical foundation for the application of HPEF in processing of Pu’er tea leaves.

Identification of QTL Affecting Protein and Amino Acid Contents in Rice

The phenotypes of protein and amino acid contents were measured in an F9 recombinant inbred line population derived from a cross between Zhenshan 97B and Delong 208. A total of 48 and 64 QTLs were identified in 2004 and 2005, respectively. The contribution of each QTL to the phenotypic variation ranged from 4.0% to 43.7%. Most QTLs co-localized, forming 29 QTL clusters on the chromosomes with three major ones detected in both years, which were mapped on chromosomes 1, 7 and 9, respectively. The two QTL clusters for amino acid content, qAa1 and qAa7, influenced almost all the traits with the allele from Zhenshan 97B, and the third QTL cluster for amino acid content, qAa9, increased the lysine content with the allele from Delong 208. A wide coincidence was found between the QTL detected under this study and the loci involved in amino acid metabolism pathways in nitrogen assimilation and transport, or protein biosynthesis. The results would facilitate the identification of candidate genes and could be used in marker-assisted selection for the favorable allele in rice quality improvement.

Physiological Processes Contributing to the Difference in Grain Amino Acid Content Between Two Hybrid Rice(Oryza sativa L.)Cultivars

Improving grain amino acid content of rice(Oryza sativa L.)is essential for the health of consumers.This study was conducted to identify the physiological processes that contribute to the higher grain amino acid content in hybrid rice cultivar Lingliangyou 268 compared to Luliangyou 996.The results showed that total amino acid content in grains was 9%higher in Lingliangyou 268 than in Luliangyou 996.There was no significant difference in grain nitrogen(N)content between Lingliangyou 268 and Luliangyou 996,while ratio of amino acid to N was 6%higher in Lingliangyou 268 compared to Luliangyou 996.A total of 16 differentially expressed proteins related to amino acid metabolism(e.g.,erythronate-4-phosphate dehydrogenase domain containing protein)were identified in grains between Lingliangyou 268 and Luliangyou 996.The identified proteins were involved in 10 molecular functions.Six of the 10 defined functions were related to binding(heterocyclic compound binding,nucleoside phosphate binding,nucleotide binding,organic cyclic compound binding,protein binding,and small molecule binding)and the other 4 defined functions were catalytic activity,enzyme regulator activity,hydrolase activity,and transferase activity.These results indicate that the higher grain amino acid content in Lingliangyou 268 compared to Luliangyou 996 is attributed to increased efficiency of converting N to amino acid that results from altered expression of proteins related to amino acid metabolism.

Protein Content and Amino Acid Composition in Grains of Wheat-Related Species

The protein content and amino acid composition for 17 wheat-related species （WRS） and three common wheats （control） were determined and analyzed, and the essential amino acids （EAAs） in WRS were evaluated according to FAO/WHO amino acid recommendations. The results showed that the mean protein content for WRS was 16.67%, which was 23.21% higher than that for the control. The mean contents （g 100 g^-1 protein） of most amino acids for WRS were lysine 2.74%, threonine 2.83%, phenylalanine 4.17%, isoleucine 3.42%, valine 3.90%, histidine 2.81%, glutamic acid 29.96%, proline 9.12%, glycine 3.59%, alanine 3.37%, and cysteine 1.57%, which were higher than those for the control. The contents of the other 6 amino acids for WRS were lower than those for the control. The materials （Triticum monococcum L., Triticum carthlicum Nevski, and Triticum turgidum L.） contained relatively high concentration of the most deficient EAAs （lysine, threonine, and methionine）. Comparing with FAO/WHO amino acid recommendations, the amino acid scores （AAS） of lysine （49.8%）, threonine （70.7%）, and sulfur-containing amino acids （74.8%） were the lowest, which were considered as the main limiting amino acids in WRS. It was observed that the materials with Triticum urartu Turn. （AA） and Aegilops speltoides Tausch. （SS） genomes had relatively high contents of protein and EAA. The contents of protein （16.91%）, phenylalanine （4.78%）, isoleucine （3.53%）, leucine （6.16%）, and valine （4.09%） for the diploid materials were higher than those for the other materials. These results will provide some information for selecting parents in breeding about nutrient quality and utilization of fine gene in wheat.

Determination and Analysis of Amino Acid Content in Maca from Different Habitats and Varieties

[Objectives]To determine and analyze amino acid content in Maca from different habitats and varieties.[Methods]Maca from two habitats and three colors were selected and a kind of turnip commonly used was to fake Maca.After optimizing the hydrolysis conditions,100 mg Maca samples were hydrolyzed in the concentration of 6 mol/L hydrochloric acid at 110℃for 24 h.The content range of amino acids in each sample was detected by HPLC.[Results]The average total content of amino acids in Maca was 9.52 g/100 g.Yunnan yellow Maca contained 16 kinds of amino acids,including 7 kinds of human essential amino acids,accounting for 17.2%of the total amino acids while Yunnan purple Maca held 16 kinds of amino acids,counting 7 kinds of human essential amino acids,accounting for 16.5%of the total amino acids.The amino acid ratio coefficient method also showed that the two kinds of Maca had higher nutritional value than the others.15 kinds of amino acids were detected in Yunnan black Maca,including 6 kinds of essential amino acids,accounting for 9.60%of the total amino acids.Among amino acids in Yunnan Maca,the highest content was Arg.A total of 12 kinds of amino acids,together with 6 essential human amino acids,were determined in Peru black Maca,accounting for 11.6%of the total amino acids.In Peru black Maca the highest concentration of amino acid was Pro.It was noteworthy that the amino acid species were comprehensive in Maca,and high level of amino acids resulted in high nutritional value.Its specific amino acid composition ratio was obviously different from Turnip,the counterfeit goods to deceive customers.[Conclusions]The method of automatic amino acid analyzer is simple and accurate,and can be used for the identification and content determination of amino acids in Maca as amino acid is an essential nutrient in Maca.

Alleviation of Adverse Effects of Salt Stress in Wheat Cultivars by Foliar Treatment with Antioxidant 2—Changes in Some Biochemical Aspects, Lipid Peroxidation, Antioxidant Enzymes and Amino Acid Contents

Ascobin (compound composed of ascorbic acid and citric acid) is considered one of exogenous protectants which may alleviate the harmful effects of salinity stress. Pot experiments were performed at the screen greenhouse of National Research Centre, Cairo, Egypt to study the effect of foliar treatment of two cultivars of wheat plant with different concentrations of ascobin (0, 200, 400 and 600 mg/l) on some biochemical parameters, antioxidant enzymes, element contents and amino acid constituents of two cultivars of wheat plant grown under different salinity levels (0.0, 3000 and 6000 mg/l) in 2011/2012 and 2012/2013. Salinity with different concentrations levels increased phenolic compounds contents of the two wheat cultivars. The activities of antioxidant enzymes (SOD, CAT, POD, PPO, AXP and GR) dramatically increased due to salinity stress. Amino acid content was increased in cultivar Sids 1, while the content was decreased in cultivar Giza 168 in all salinity treatments. Increments in the above mentioned parameters compared to the untreated plants at normal and stressed conditions. The magnitude of increments was much more pronounced in response to 600 mg/l of ascobin. It could be concluded that, foliar treatment of wheat cultivars with ascobin could partially alleviate the harmful effect of salinity especially at the lower levels of salinity of the two cultivars of wheat at most of the studied parameters.

Effect of nitric oxide synthase inhibitor N^G-nitro-L-arginine on the content of amino acid in ischemic brain tissues of rats

BACKGROUND： Nitric oxide synthase （NOS） inhibrtors have been widely used to investigate the role of NO on cerebral ischemic injury, but the results are controversial. Moreover, it has been considered to aggravate the ischemic neuronal damage with the release of excessively excitatory amino acids （EAA） during cerebral ischemia. On the other hand, some inhibitory amino acid is suggested to be important for the neuronal protection against ischemic brain damage. Our study has recently showed that treatment with the NOS inhibitor NG-nitro-L-arginine （L-NA） reduced focal cerebral ischemic damage. The effect of L-NA on the contents of excitatory and inhibitory amino acid in the rat brain following cerebral ischemia is still unclear. OBJECTIVE： By evaluating the effect of NOS inhibitor, L-NA on the contents of aspartate, glutamate, glycine and γ-aminobutyric acid （GABA） in striatum, hippocampus and cortex in the rat brain following cerebral ischemia respectively, to investigate the beneficial effect of L-NA on cerebral ischemic injury and the possible mechanism. DESIGN： A randomized and controlled experiment SETTING ： Department of Pharmacology, Hebei Academy of Medical Sciences MATERIALS： A total of 42 male healthy SD rats （grade Ⅱ, weighting 250-300 g） were provided by the Experimental Animal Center of Hebei Province （Certification： 04036）. Aspartate, glutamate, glycine, GABA, L-NA and 2,3,5-triphenyltetrazolium chloride （TTC） were obtained from Sigma Chemicals Co, St Louis, MO, USA. HPLC-ultraviolet detector system consisted of Agilent 1100 HPLC. METHODS： The experiment was carried out in Department of Pharmrcology, Hebei Academy of Medical Sciences from June 2005 to June 2006. Rats were randomly divided into three groups： sham-operated group （n = 6）, ischemic group （n = 18）, L-NA group （n = 18）. The model of focal cerebral ischemia in rat was prepared with intraluminal line occlusion methods. In sham-operated rats, the external carotid artery was surgically prepared, but the filament was not inserted. Each group was further divided into 3 subgroups （n = 6 for each）： drugs were administrated at 2, 6 and 12 hours after the middle cerebral artery occlusion （MCAO） respectively. L-NA （20 mg/kg, ip） was administrated, twice a day, for 3 consecutive days. Same volume of normal saline was administrated in ischemic and sham operation groups. The changes of infarcted volume and the contents of amino acids were respectively assayed. Image analysis software was used for the measurement of the infarcted area. The results were expressed as a percentage of the infarcted volume of cerebral/volume of whole brain （IV%） in order to control for edema formation. The contents of aspartate, glutamate, glycine and GABA in striatum, hippocampus and cortex in the rat brain following cerebral ischemia were respectively measured by HPLC method. All data were analyzed with one-way ANOVA and Dunnett＇s test. MAIN OUTCOME MEASURES： （1） The volume of cerebral infarction; （2） The contents of aspartate, glutamate glycine and GABA in brain tissue after cerebral ischemia. RESULTS ： All 42 rats were involved in the final analysis. （1） Infarcted volume： Volume was 0 in sham-operated group. When L-NA was administrated at 2 and 6 hours after MCAO, the infarcted volume was （20.13±3.59）% and （23.12±5.84）% in L-NA group, which was not similar to that in ischemic group [（22.10±3.98）%, （25.38± 5.37）%, P〉 0.05]. However, the infarcted volume was markedly decreased compared with that of ischemic group when L-NA was administrated at 12 hours after MCAO [（26.11±3.55）% and （37.15±3.58）%, P 〈 0.01]. Changes of amino acid content： At 2 and 6 hours after ischemia, the contents of aspartate, glutamate, glycine and GABA in striatum, hippocampus and cortex in ischemic group were significantly increased compared with those in sham-operated group （ P〈 0.05-0.01）. However, contents in L-NA group were similar to those in ischemic group （P 〉 0.05）. At 12 hours after ischemia, the contents of aspartate [（0.21 ±0.06）, （0.36±0.05）, （0.29±0.12） mg/g] and glutamate [（0.55±0.06）, （0.78±0.10）, （0.52±0.10） mg/g] in striatum, hippocampus and cortex in L-NA group were significantly decreased compared with those in ischemic group [（0.49±0.17）, （0.63± 0.03）, （0.51±0.15） mg/g; （0.98±0.30）, （1.15±0.15）, （0.93±0.15） mg/g, P〈 0.05-0.01]. Glycine in hippocampus was （0.40±0.07） mg/g, which was higher than that in ischemic group [（0.21±0.07） mg/g, P 〈 0.05]. GABA in striatum, hippocampus and cortex was （0.93±0.10）, （0.62±0.12） and （0.81 ±0.10） mg/g, respectively, which was higher than that in ischemic group [（0.60±0.08）, （0.37±0.17）, （0.59±0.10） mg/g, P 〈 0.05-0.01]. CONCLUSION ： It may be concluded that L-NA have beneficial effect on ischemic cerebral injury in ischemic later stage in rats. The possible mechanism is that L-NA can decrease the contents of aspartate and glutamate, increase the contents of glycine and GABA.

饲料蛋白质水平对低盐环境中红螯螯虾生长的影响

【目的】研究红螯螯虾在低盐(1.5‰)养殖条件下的蛋白质营养需求,为低盐水体规模化养殖红螯螯虾人工配合饲料的研制提供理论依据。【方法】配制6种不同蛋白质水平,即26.83%(D1)、29.71%(D2)、32.59%(D3)、35.42%(D4)、38.37%(D5)和41.09%(D6)的等能饲料,以初始体重为0.41±0.01 g的红螯螯虾幼虾为研究对象,养殖56 d,分析饲料蛋白质水平对低盐养殖环境中红螯螯虾幼虾的生长性能、肌肉基本营养成分及氨基酸含量的影响。【结果】在低盐养殖环境中,饲料蛋白质水平对红螯螯虾增重率、特定生长率、粗蛋白质含量、粗脂肪含量及氨基酸含量有显著影响(P<0.05,下同),对存活率、水分和灰分无显著影响(P>0.05,下同)。饲料中蛋白质水平的提高对各组红螯螯虾的增重率和特定生长率的影响趋势为先升后降,D3处理的增重率最高,显著高于其余各组,D3~D6处理的特定生长率差异不显著,但显著高于D1和D2处理。虾肌肉粗蛋白质含量与饲料蛋白质水平呈正相关,高蛋白质水平组(D5和D6处理)粗蛋白质含量显著高于其余各组。与之相反,虾肌肉粗脂肪含量与饲料蛋白质水平呈负相关,随着饲料蛋白质水平持续增长,肌肉粗脂肪含量显著下降。肌肉中共测定出17种氨基酸,其中7种必需氨基酸(E_(AA))、2种半必需氨基酸(HE_(AA))、8种非必需氨基酸(NE_(AA))。饲料蛋白质水平在29.71%~41.09%的各组氨基酸总量均随着饲料蛋白质水平的升高而显著升高。【结论】低盐养殖环境中,以特定生长率为评价标准,红螯螯虾饲料最适蛋白质水平为36.09%,以肌肉鲜味氨基酸占比(WDAA/WTAA)为评价标准,红螯螯虾饲料最适蛋白质水平为30.96%。

蜜环菌人工菌棒基质碳氮比对乌天麻产量及营养品质的影响

目的分析蜜环菌人工菌棒基质碳氮比对乌天麻产量及基本营养成分含量的影响,并对乌天麻氨基酸品质进行评价。方法通过大棚内随机区组实验,测定不同种植模式下乌天麻的基本营养成分含量,对其进行单因素方差分析和多重比较,通过氨基酸评分法对乌天麻中氨基酸营养价值进行评价。结果蜜环菌人工菌棒基质碳氮比对乌天麻的产量、基本营养成分含量及氨基酸的营养品质均有显著影响;蜜环菌人工菌棒基质碳氮比为75.94时种植的乌天麻,其各项营养指标接近对照种植的乌天麻的各项营养指标,显著大于蜜环菌人工菌棒基质碳氮比为60.69、126.39时种植的乌天麻的各项营养指标。蜜环菌人工菌棒基质碳氮比为75.94时种植的乌天麻,其必需氨基酸含量与总氨基酸含量的比值为37.03%,接近40%;必需氨基酸含量与非必需氨基酸含量的比值为58.79%,接近60%;必需氨基酸的氨基酸比值、必需氨基酸的比值系数分、必需氨基酸比值系数与联合国粮食及农业组织/世界卫生组织提出的氨基酸理想模式较接近。结论利用蜜环菌人工菌棒种植乌天麻可以获得基本营养成分含量高、氨基酸丰富、必需氨基酸的组成比例相对合理、符合人体吸收利用需求、具有较高营养价值的乌天麻。

不同水分条件下氨基酸添加对温带暗棕壤碳氮含量和甲烷排放的影响

【目的】解析土壤pH值与土壤氮以及CH_(4)排放速率与土壤碳氮含量间的相互关系,为明确碳氮转化及温室气体排放规律、优化温带森林暗棕壤的水分管理提供依据。【方法】以温带森林暗棕壤为研究对象,采用室内培养法,设置水分条件为土壤饱和持水量(WHC)的40%、60%、90%,通过向温带暗棕壤中添加两种不同性质的氨基酸,探讨其对土壤碳氮含量及CH_(4)排放的潜在影响,运用Pearson相关分析法分析土壤碳氮含量、pH值及CH_(4)排放速率间的相关性。【结果】(1)氨基酸处理显著增加了土壤可溶性有机碳(DOC)含量、铵态氮(NH_(4)^(+)-N)含量及CH_(4)排放速率。亮氨酸处理使DOC、NH_(4)^(+)-N含量分别升高21.39%、45.10%,CH_(4)排放速率较CK升高3.20倍,甲硫氨基酸使DOC、NH_(4)^(+)-N含量分别升高21.39%、72.71%,CH_(4)排放速率较CK升高7.00倍;(2)不同氨基酸对土壤硝态氮(NO_(3)^(-)-N)含量的影响存在差异。亮氨酸处理使土壤NO_(3)^(-)-N含量升高了8.41%,但其对于土壤硝化作用的影响可能存在滞后性,而甲硫氨基酸能够显著抑制土壤硝化作用,NO_(3)^(-)-N含量显著降低了37.90%;(3)土壤不同水分条件对土壤DOC、NH_(4)^(+)-N、NO_(3)^(-)-N含量及CH_(4)排放速率均存在显著影响。90%WHC使DOC含量升高11.95%~19.91%,使NH_(4)^(+)-N升高19.83%~35.46%,使NO_(3)^(-)-N降低10.05%~23.79%,使CH_(4)排放速率升高至另外两种水分条件的1.48~2.06倍。60%WHC条件使NH_(4)^(+)-N升高13.05%,使NO_(3)^(-)-N含量升高24.62%。60%WHC可能是温带暗棕壤硝化作用的最适含水量,90%WHC条件有利于DOC积累,同时对NO_(3)^(-)-N的产生存在明显抑制作用;(4)土壤pH与N H4+-N含量呈极显著正相关,与NO_(3)^(-)-N含量呈正相关。CH_(4)排放速率与NO_(3)^(-)-N含量呈极显著负相关,与NH_(4)^(+)-N含量呈负相关,与DOC含量呈极显著正相关。【结论】不同性质氨基酸添加在温带森林暗棕壤碳氮含量及CH_(4)排放中发挥的作用不尽相同。一定范围内,土壤水分含量的升高有利于土壤NH_(4)^(+)-N、NO_(3)^(-)-N、DOC的积累及CH_(4)的排放,但土壤高含水量条件对NO_(3)^(-)-N的产生具有抑制作用。因此,在研究温带森林暗棕壤碳含量、CH_(4)排放及氮转化机制时,建议关注不同氨基酸的差异性作用,同时考虑水分的变化。

不同产地金耳中氨基酸含量分析及营养价值评价

目的测定不同产地金耳中氨基酸的组成及含量,并评价其营养价值。方法利用氨基酸分析仪测定云南、陕西、福建、西藏和甘肃金耳中氨基酸的含量,比较不同产地金耳中氨基酸组成和含量之间的差异,并采用氨基酸评分(amino acid score,AAS)、氨基酸比值(amino acid ratio,RAA)、氨基酸比值系数(ratio coefficient of amino acid,RC)和氨基酸比值系数评分(score of RC,SRC)以及主成分分析等对不同产地金耳中氨基酸的营养价值进行综合评价。结果不同产地金耳中均检出17种氨基酸,其氨基酸总含量在9.25~19.50g/100g之间;必需氨基酸含量在2.72~6.07g/100g之间,占总氨基酸含量在26.6%~31.7%之间;非必需氨基酸含量在6.33~13.43 g/100 g之间,占总氨基酸含量在68.3%~73.4%之间。5个产地金耳中4种呈味氨基酸含量由高到低依次为:甜味氨基酸>鲜味氨基酸>苦味氨基酸>芳香族氨基酸,而不同产地金耳中呈味氨基酸总含量由低到高依次为:陕西<云南<福建<甘肃<西藏。利用主成分分析对不同产地金耳中17种氨基酸含量进行评价,共提取1个主成分,累积方差贡献率达到95.94%。结论不同产地金耳中氨基酸含量之间虽有差异性,但均含有种类丰富的氨基酸,其营养价值高,可作为优质蛋白的植物资源。

不同品种山药氨基酸组成成分分析及综合评价

目的探究不同品种山药中氨基酸的含量差异。方法参照GB5009.124—2016《食品安全国家标准食品中氨基酸的测定》,利用全自动氨基酸分析仪测定山药中氨基酸含量,通过相关性、主成分分析进行数据分析及综合性评价。结果20种山药中均检测出16种氨基酸,总氨基酸含量为7.21~8.71 g/100 g,必需氨基酸占比为27.86%~34.89%。各地均以精氨酸和谷氨酸含量最高,总含量分别为20.77 g/100 g和26.18 g/100 g。采用主成分分析法提取3个主成分,累积方差贡献率为82.78%,综合评分排名前3位的品种分别是利川山药、西施山药、云岭山药。结论通过主成分分析法区分不同品种山药中氨基酸差异,为山药中氨基酸评价、食药资源的开发利用、良种选育、种植技术改良等方面提供可行性参考。

瓜蒌皮注射液及其中间体中17种氨基酸含量测定及其变化规律研究

目的测定瓜蒌皮注射液及其中间体中天冬氨酸、谷氨酸、丝氨酸、甘氨酸、苏氨酸、瓜氨酸、精氨酸、丙氨酸、γ-氨基丁酸、酪氨酸、缬氨酸、苯丙氨酸、异亮氨酸、鸟氨酸、亮氨酸、赖氨酸、脯氨酸的含量,并分析其变化规律。方法OPA-FMOC在线衍生化分析采用Waters XBridge C_(18)色谱柱(4.6 mm×100 mm,3.5μm);流动相磷酸盐缓冲液-[甲醇-乙腈-水(45∶45∶10)],梯度洗脱;体积流量1 mL/min;柱温45℃;检测波长262、338 nm。主成分分析、热图分析对10道工序相应中间体的6批样品进行化学模式识别。结果17种氨基酸在各自范围内线性关系良好(R^(2)>0.9980),平均加样回收率83.4%~119.5%,RSD 0.91%~7.94%。相同工序不同批次样品较聚集,不同工序相应中间体聚为3组。醇沉和阳离子交换柱对氨基酸组成影响最大。结论本实验可为瓜蒌皮注射液质量控制的关键因素提供重要参考,以保证终产品的稳定性和均一性。

外源氨基酸对液态发酵法白酒风味品质的影响

在液态法发酵白酒的基础上,添加不同质量浓度的甘氨酸(Gly)、亮氨酸(Leu)、缬氨酸(Val)、苯丙氨酸(Phe),探究外源氨基酸对液态法发酵白酒产生的酒精度、总酸、总酯和主要风味物质的影响。结果表明,甘氨酸对白酒酒精度、辛酸乙酯含量的影响最大,最大值比空白组分别增加了7.14%、69.75%;亮氨酸对总酸、总酯、异戊醇的影响最大,最大值比空白组分别增加了8.10%、12.07%和92.94%;缬氨酸对异丁醇的影响最大,最大值比空白组增加了404.28%;Phe对苯乙醇、乙酸乙酯的影响最大,最大值比空白组分别增加了81.54%、32.66%;随着四种氨基酸添加量的增加,酒精度和总酸产量先升高后降低,其中甘氨酸和亮氨酸添加量分别为400 mg/L时,酒精度和总酸最大分别为12%vol和0.227 g/L;四种氨基酸对白酒总酯的生成影响明显,其中亮氨酸添加量为600 mg/L时总酯产量最大,为0.43 g/L;由挥发性风味物质聚类结果可知,亮氨酸、缬氨酸和苯丙氨酸对液态发酵法白酒风味物质生成影响较大。在液态发酵法白酒制备中合理添加氨基酸,可明显提高液态发酵法白酒酒精、总酸、总酯的含量,有效调节高级醇产生。

不同低温循环水暂养时间对克氏原螯虾肌肉品质和健康状况的影响

为探讨低温(5~6℃)循环水暂养时间对克氏原螯虾肌肉品质、健康状况的影响,各处理组随机选取20尾初始体重为(25.28±1.56) g的克氏原螯虾进行低温暂养,对试验起始阶段(对照)与低温暂养15 d、30 d的克氏原螯虾的肌肉营养成分、肌肉氨基酸组成和含量、肌肉离心损失率和蒸煮损失率、肌肉质构特性及肝胰腺抗氧化指标进行分析。结果显示,与试验起始阶段相比,随着低温暂养时间延长至30 d,克氏原螯虾肌肉脂肪含量显著下降(P<0.05);随着暂养时间延长至15 d、30 d,克氏原螯虾肌肉的蛋白质含量显著下降(P<0.05)。与试验起始阶段相比,低温暂养15 d、30 d的克氏原螯虾肌肉中甲硫氨酸含量、精氨酸含量、谷氨酸含量、天冬氨酸含量、丙氨酸含量、甘氨酸含量、酪氨酸含量均无显著变化,而组氨酸含量呈下降趋势,其余氨基酸含量从低温暂养15 d或30 d开始显著上升(P<0.05);必需氨基酸含量、鲜味氨基酸含量和总氨基酸含量整体较为稳定(P>0.05)。与试验起始阶段相比,低温暂养15 d、30 d的克氏原螯虾肌肉的离心损失率、蒸煮损失率的变化不显著(P>0.05),肌肉的硬度从低温暂养15 d开始显著下降,肌肉的恢复性在低温暂养30 d时显著下降(P<0.05),肌肉的咀嚼性、弹性无显著变化(P>0.05)。与试验起始阶段相比,低温暂养15 d、30 d的克氏原螯虾肝胰腺中谷胱甘肽过氧化物酶活性呈显著下降趋势(P<0.05),并在低温暂养30 d时降至最低值,显著低于试验初始阶段。研究结果显示,在低温下暂养30 d不会显著影响克氏原螯虾的肌肉品质和健康状况,后期可调整暂养参数以完善养殖技术。

UPLC-MS/MS法同时测定阿胶中18种核苷、游离氨基酸的含量

目的建立UPLC-MS/MS法同时测定阿胶中Asp、Guad、Adeno、Arg、Ade、Cyti、Phe、Leu、Ile、Glu、Ser、Gln、Gly、Ala、Hyp、Thr、Pro、Lys的含量。方法分析采用WatersBEHC18色谱柱(2.1mm×50mm,1.7μm);流动相乙腈(含0.1%甲酸)-水;体积流量0.35mL/min;柱温45℃;电喷雾离子源;正离子扫描;多反应监测模式。再采用层次聚类分析、主成分分析和正交偏最小二乘判别分析进行化学模式识别。结果18种核苷、游离氨基酸在各自范围内线性关系良好(r≥0.9990),平均加样回收率98.0%~104.9%,RSD1.6%~4.9%。17批样品聚为2类,2种主成分累积方差贡献率为60.75%,Leu、Phe、Ade和Guad是潜在指标成分。结论该方法稳定可靠,可用于阿胶的质量控制。

真空脉动干燥温度对黄花菜理化性质与微观结构的影响

鲜黄花菜含水率较高,导致采后品质快速下降。探讨适合黄花菜的加工方法对延长黄花菜的货架期非常重要。为探究不同真空脉动干燥(PVD)工艺条件对黄花菜营养成分、色泽、风味、复水率及微观结构的影响,以便提高干制黄花菜品质,选用PVD设备干制黄花菜,研究真空保持时间(10 min)和常压保持时间(5 min)条件下不同干燥温度(65,70,75,80,85℃)对黄花菜品质的影响。采用主成分分析法和偏最小二乘法对黄花菜干燥工艺、风味组成以及特征滋味进行判别分析。结果表明,自然干燥(CK)黄花菜中游离氨基酸含量最多,为0.858 mg/g,△E值最大,为16.47,进一步表明样品整体质量较差。PVD干燥后黄花菜色泽鲜亮,复水性能较好,蛋白质和黄酮含量显著增加。当PVD 80℃时,原色保留率最大(△E=7.28),游离氨基酸含量最高(0.818 mg/g)。当PVD 75℃时,样品中蛋白质(7.331 g/L)和Ga(1072.445μg/kg)含量最高。当PVD 70℃时,黄菜样品中β-折叠和α-螺旋含量占比最多,为35%。当PVD 65℃时,黄酮含量(1.653 mg/g)和复水率最高(3.04%),并且可较好地保留无机硫化物、氮氧化合物及萜类物质。此外,通过偏最小二乘判别分析得出天门冬氨酸、组氨酸、丝氨酸、谷氨酸和丙氨酸为黄花菜特征滋味物质。结论:不同PVD干燥温度导致黄花菜的理化性质和营养成分不同,研究结果可为满足不同质量属性要求和消费者接受度提供适合的工艺参数。

“2+3”模式下种鸽氨基酸理想模式的研究

试验旨在探究“2+3”模式下种鸽氨基酸理想模式。依据扣除法原理,根据现有氨基酸需要量标准和目前的研究结果规划出一种氨基酸模式,依次将模式中赖氨酸(Lys)、蛋氨酸(Met)、色氨酸(Trp)、苏氨酸(Thr)、亮氨酸(Leu)各扣除20%,而非扣除的氨基酸保持其水平不变来确定扣除某一种氨基酸后对“2+3”模式下种鸽生产性能和血液氨基酸含量的影响,确定出理想的氨基酸比例。试验选择同一批次的144对种鸽随机分为两组,一组为72对种鸽哺乳4日龄乳鸽,另一组为72对种鸽哺乳10日龄乳鸽,两试验分别各设6个处理组,为6种氨基酸模式,每个处理12对种鸽(重复),按照50%颗粒料+50%的原粮配制种鸽饲粮。结果表明:各处理乳鸽平均日增重无显著差异(P>0.05),但扣除20%赖氨酸处理较高,且该组乳鸽死亡率低;各处理种公鸽血液氨基酸含量无显著差异(P>0.05),而种母鸽血液中天冬氨酸含量以扣除20%赖氨酸处理最低,且显著低于扣除20%蛋氨酸、色氨酸和亮氨酸处理(P<0.05)。综上,“2+3”模式下种鸽理想氨基酸模式是赖氨酸、蛋氨酸、色氨酸、苏氨酸、亮氨酸水平为0.88%、0.55%、0.65%、0.2%和1.5%。

文蛤(Meretrix petechialis)多种游离氨基酸含量的综合评价

为了明确文蛤游离氨基酸的组成、含量及其风味特性,本研究以文蛤的11个全同胞家系为研究对象,利用氨基酸自动分析仪测定文蛤足组织中游离氨基酸的种类和含量,通过主成分分析、TOPSIS分析进行综合评价。结果显示,文蛤家系游离氨基酸总量均在473~816mg/100g,均值为638mg/100g。呈鲜味氨基酸含量为270~570 mg/100g,占总含量的56.0%~70.8%,是最主要的呈味氨基酸。15种游离氨基酸通过主成分分析提取到2个主成分,其累积方差贡献率为89.54%,可代表文蛤中游离氨基酸的综合信息。游离氨基酸T值较高的家系依次是22A8、22A5、22A1和22A6,与TOPSIS分析结果一致。结果表明上述4个文蛤家系可作为游离氨基酸含量综合性状突出的优良种质资源用于文蛤的选育工作。

不同干燥方式对毛竹笋全粉中氨基酸含量和蛋白质结构的影响

为探究不同干燥方式对竹笋全粉氨基酸含量及蛋白质结构的影响,该实验采用喷雾干燥(spray drying,SD)、热风干燥(hot air drying,HAD)、微波干燥(microwave drying,MD)、低温真空干燥(low-temperature vacuum drying,LVD)4种方式制备毛竹笋全粉(Phyllostachys pubescens shoot powder,PPSP),分析了4种干燥方式的PPSP氨基酸组成及含量,并基于拉曼光谱酰胺Ⅰ带比较了4组样品蛋白质二级结构变化。结果表明,LVD制备的PPSP总氨基酸含量最高,为29.19 g/100 g,其次为SD,HAD制备的PPSP总氨基酸含量最低。LVD组的PPSP中必需氨基酸含量最高,为10.43 g/100 g,占总氨基酸含量的35.73%。LVD和SD制备的PPSP中呈味氨基酸含量分别为17.58 g/100 g、15.81 g/100 g,显著高于HAD和MD组的呈味氨基酸含量。LVD样品中氨基酸组成最接近于标准模式谱。通过主成分分析提取出2个主成分,累计方差贡献率达89.45%,综合评分结果为:LVD>SD>MD>HAD,聚类热图将4种干燥方式分为3类。干燥后的PPSP蛋白质中β-折叠结构最高,占总二级结构的74.66%~83.35%,HAD样中β-折叠、α-螺旋结构含量明显高于其他样品。该研究可为毛竹笋干燥及竹笋全粉的开发利用提供理论参考。