发酵乳在发酵和低温储存过程中必需氨基酸变化研究

研究了混菌发酵乳与单菌发酵乳在发酵和4℃储存过程中必需氨基酸含量变化,并与作为底物的脱脂乳粉氨基酸组分进行对比。研究表明,在发酵和储存过程中总游离氨基酸含量增加;随储存时间延长,必需氨基酸含量增加,约占总游离氨基酸含量13%—17%;混菌发酵乳游离氨基酸和必需氨基酸含量高于单菌发酵乳。     

内蒙古地区不同养殖草食动物背最长肌氨基酸组成及营养价值评价

以内蒙古地区集约化养殖草食动物牛、绵羊、山羊和驴背最长肌为研究对象,以鸡胸肉为参照,采用全自动氨基酸分析仪内标法检测氨基酸含量,评价肌肉氨基酸组成及营养价值。结果表明：各氨基酸在不同动物肌肉中的含量均呈显著差异（P＜0.05）;鸡胸肉、牛肉和山羊肉总必需氨基酸含量显著高于绵羊肉（P＜0.05）,驴肉与其他肉无显著差异;牛肉和驴肉总非必需氨基酸含量显著高于山羊肉（P＜0.05）,其他肉无显著差异。不同草食动物肌肉必需氨基酸指数（essential amino acid index,EAAI）均高于95,属于优质蛋白质来源,EAAI顺序为山羊肉＞鸡胸肉＞绵羊肉＞牛肉＞驴肉;驴肉甜味氨基酸含量显著高于其他肉（P＜0.05）,牛肉和绵羊肉鲜味氨基酸含量显著高于其他肉（P＜0.05）,鸡胸肉苦味氨基酸含量显著高于其他肉（P＜0.05）,牛肉和绵羊肉总呈味氨基酸含量显著高于其他肉（P＜0.05）;以氨基酸相对含量聚类,绵羊肉和牛肉在图谱中最接近,驴肉处于图谱最远端。     

花边骡鸭理想氨基酸模式的研究

研究应用氨基酸扣除法原理,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来确定对花边骡鸭生产性能和血液生化指标的影响.结果表明:花边骡鸭在1～3周龄4种必需氨基酸理想比例为赖氨酸∶蛋氨酸∶色氨酸∶苏氨酸=100∶37∶67∶19;花边骡鸭在4～8周龄4种必需氨基酸理想比例为赖氨酸∶蛋氨酸∶苏氨酸∶色氨酸=100∶33∶64∶18.     

野生和养殖背角无齿蚌矿质元素和氨基酸含量的特征分析

以野生和养殖水域背角无齿蚌软组织为材料,采用电感耦合等离子质谱和液相色谱测试方法,分别研究其软组织中6种矿质元素和18种水解氨基酸的含量。结果表明：虽然两生境背角无齿蚌中含有的6种矿质元素和氨基酸含量高低顺序相似,但在部分矿质元素和个别氨基酸的含量上两者差异明显。野生蚌中矿质元素Ca、Na、Mg、Sr、Se的含量高于或接近养殖蚌(特别是Mg和Sr元素的含量显著较高),但后者元素K的含量极显著高于前者。两水域蚌的氨基酸组成基本一致,17种氨基酸的含量没有显著性差异,而养殖蚌牛磺酸的含量显著高于野生蚌。养殖蚌和野生蚌必需氨基酸含量分别为37.65%和36.75%,必需氨基酸与非必需氨基酸的比值分别为60.38%和58.11%。     

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GB 5009.124—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7.21~8.62 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。     

不同生长阶段大菱鲆的氨基酸评价分析

对不同生长阶段的200~1600 g大菱鲆氨基酸组成进行了对比分析,结果表明：不同生长阶段的大菱鲆蛋白质中,EAA/TAA47~48%、EAA/NEAA 87~93%,其变异系数在2%左右,符合FAO/WHO公布的氨基酸理想模式（EAA/TAA在40%左右、EAA/NEAA〉60%）,说明大菱鲆是高品质的食用蛋白源;不同生长阶段的大菱鲆必需氨基酸组成模式各不相同,需要针对不同的生长阶段,配置相应的专用饲料。本研究可以优化大菱鲆配合饲料配方,为不同生长阶段的大菱鲆配合饲料的研究和开发提供可靠的资料支持和科学依据。     

Effects of supplemental chromium propionate and rumen-protected amino acids on productivity,diet digestibility,and energy balance of peak-lactation dairy cattle

Chromium (Cr) feeding in early lactation increased milk production in some studies, but responses to dietary Cr during peak lactation have not been evaluated. Furthermore, interactions of essential amino acids (AA) and Cr have not been explored. Our objective was to evaluate responses to CrPr (KemTRACE chromium propionate 0.04%, Kemin Industries Inc., Des Moines, IA) and rumen-protected Lys (LysiPEARL, Kemin Industries Inc.) and Met (MetiPEARL, Kemin Industries Inc.) and their interaction in peak-lactation cows. Forty-eight individually fed Holstein cows (21 primiparous, 27 multiparous, 38 ± 15 d in milk) were stratified by calving date in 12 blocks and randomly assigned to 1 of 4 treatments within block. Treatments were control, CrPr (8 mg/d of Cr), RPLM (10 g/d of Lys and 5 g/d of Met, intestinally available), or CrPr plus RPLM. Treatments were premixed with ground corn and top-dressed at 200 g/d for 35 d. Diets consisted of corn silage, alfalfa hay, and concentrates, providing approximately 17% crude protein, 31% neutral detergent fiber, and 40% nonfiber carbohydrates. Dry matter intake (DMI) significantly increased with the inclusion of CrPr (22.2 vs. 20.8 ± 0.67 kg/d), and energy-corrected milk (ECM) yield tended to increase. In addition, CrPr increased milk protein yield and tended to increase DMI in primiparous cows but not in multiparous cows. A CrPr × week interaction was detected for milk lactose content, which was increased by CrPr during wk 1 only (4.99 vs. 4.88 ± 0.036%). As a proportion of plasma AA, lysine increased and methionine tended to increase in response to RPLM, but the inclusion of RPLM decreased N efficiency (milk protein N:N intake). Digestible energy intake, gross energy digestibility, and energy balance were not affected by treatments. We observed no treatment effects on feed efficiency or changes in body weight or body condition score. In summary, feeding CrPr increased DMI and tended to increase ECM in cows fed for 5 wk near peak lactation, with primiparous cows showing greater responses in DMI and milk protein yield than multiparous cows.     

6 种市售工厂化栽培金针菇的氨基酸组成及蛋白质营养评价

为分析工厂化栽培金针菇的蛋白质营养,本研究测定6?种来自不同生产企业的市售金针菇样品中粗蛋白含量及氨基酸组成,分析其中呈味氨基酸的含量,并通过计算蛋白质的氨基酸评分、化学评分、氨基酸比值系数分和必需氨基酸指数,以及预测蛋白质校正氨基酸计分等非生物学指标,评价金针菇的蛋白质营养价值。结果表明,6?种金针菇样品均含有18?种水解氨基酸,其中呈味氨基酸含量比例为56.28%～57.37%。必需氨基酸含量接近WHO/FAO模式,其中蛋氨酸、赖氨酸含量丰富,限制氨基酸为缬氨酸和异亮氨酸。6?种市售金针菇的氨基酸比值系数分为72.61～82.07,必需氨基酸指数均高于90,与卵清蛋白接近。上述结果表明工厂化栽培的金针菇中呈味氨基酸含量丰富,含有利于人体吸收的优质蛋白,具有较大的风味食品开发潜力,适合与谷物、肉类等进行膳食搭配以促进人体对氨基酸的平衡摄取。     

八眉猪不同部位肌肉氨基酸组成分析及营养评价

为深入了解八眉猪氨基酸的营养价值,测定了八眉猪背肌、腹肌两个部位中的氨基酸含量,分析其氨基酸种类与比例,并基于FAO/WHO模式,对其营养价值进行了评价。结果表明,八眉猪背肌与腹肌两部位共检出17种氨基酸,除含量存在显著差异外,其分布、比例、构成表现出一致性。EAA/TAA、EAA/NAA完全符合FAO/WHO提出的理想蛋白的要求。蛋氨酸+胱氨酸为第一限制性氨基酸,赖氨酸含量高,氨基酸组成接近FAO/WHO模式,贴近标准蛋白模式,说明八眉猪有很高的营养价值。背肌、腹肌均含有丰富的风味氨基酸,占到氨基酸含量总量的近50%,腹肌较背肌味道更鲜美。青海八眉猪氨基酸种类齐全,营养价值高,且味道鲜美,作为地方优质猪种资源,具有开发潜力。     

谷氨酰胺(Gln)活性肽营养液的研究进展

对G1n小肽在氨基酸营养液中的使用以及G1n小肽的稳定性和代谢机制进行了论述。G1n是一种“条件必需氨基酸”，但Cln的水溶液不稳定，因而在氨基酸输液或氨基酸营养被中，用G1n小肽代替G1n单体使用。G1n小肽含有取代的α—NH2，使Cln小肽的稳定性大大增加。     

不同产地野生长柄扁桃仁氨基酸组成及营养价值评价

采集主产区陕西省和内蒙古自治区11 个地区的长柄扁桃仁为实验材料,采用氨基酸自动分析仪测定其氨基酸组成,并进行了营养价值评价。结果表明,不同产地长柄扁桃仁总氨基酸含量在21.74～32.35 mg/g之间,平均为26.78 mg/g;必需氨基酸占总氨基酸比例范围在24.86%～28.22%之间,第一限制氨基酸为蛋氨酸,氨基酸比值系数分平均值为69.13;以氨基酸总量、必需氨基酸含量等指标,将11 个产地长柄扁桃仁氨基酸聚类分为4 类,其中呼和浩特市小井沟生态园长柄扁桃仁蛋白含量最高,品质最好;长柄扁桃仁中味觉氨基酸和药用氨基酸含量丰富,开发利用潜质较大。     

Methionine supply during the periparturient period enhances insulin signaling,amino acid transporters,and mechanistic target of rapamycin pathway proteins in adipose tissue of Holstein cows

Enhanced postruminal supply of Met during the periparturient period increases dry matter intake and milk yield. In nonruminants, adipose tissue is responsive to AA supply, and can use AA as fuels or for protein synthesis regulated in part via insulin and mechanistic target of rapamycin (mTOR) signaling. Whether enhancing supply of Met has an effect on insulin and mTOR pathways in adipose tissue in peripartal cows is unknown. Multiparous Holstein cows were assigned from ?28 to 60 d relative to parturition to a basal diet (control; 1.47 Mcal/kg of dry matter and 15.3% crude protein prepartum; 1.67 Mcal/kg and 17.7% crude protein postpartum) or the control plus ethyl-cellulose rumen-protected Met (RPM). The RPM was fed individually at a rate of 0.09% of dry matter intake prepartum and 0.10% postpartum. Subcutaneous adipose tissue harvested at ?10, 10, and 30 d relative to parturition (days in milk) was used for quantitative PCR and Western blotting. A glucose tolerance test was performed at ?12 and 12 d in milk to evaluate insulin sensitivity. Area under the curve for glucose in the pre- and postpartum tended to be smaller in cows fed Met. Enhanced Met supply led to greater overall mRNA abundance of Gln (SLC38A1), Glu (SLC1A1), l-type AA (Met, Leu, Val, Phe; SLC3A2), small zwitterionic α-AA (SLC36A1), and neutral AA (SLC1A5) transporters. Abundance of AKT1, RPS6KB1, and EIF4EBP1 was also upregulated in response to Met. A diet × day interaction was observed for protein abundance of insulin receptor due to Met cows having lower values at 30 d postpartum compared with controls. The diet × day interaction was significant for hormone-sensitive lipase due to Met cows having greater abundance at 10 d postpartum compared with controls. Enhanced Met supply upregulated protein abundance of insulin-responsive proteins phosphorylated (p)-AKT, peroxisome proliferator-activated receptor gamma, and fatty acid synthase. Overall abundance of solute carrier family 2 member 4 tended to be greater in cows fed Met. A diet × day interaction was observed for mTOR protein abundance due to greater values for RPM cows at 30 d postpartum compared with controls. Enhanced RPM supply upregulated overall protein abundance of solute carrier family 1 member 3, p-mTOR, and ribosomal protein S6. Overall, data indicate that mTOR and insulin signaling pathways in adipose tissue adapt to the change in physiologic state during the periparturient period. Further studies should be done to clarify whether the activation of p-AKT or increased availability of AA leads to the activation of mTOR.     

Effects of reduced dietary protein and supplemental rumen-protected essential amino acids on the nitrogen efficiency of dairy cows

When fed to meet the metabolizable protein requirements of the National Research Council, dairy cows consume an excess of N, resulting in approximately 75% of dietary N being lost to the environment as urine and feces. Reductions in environmental N release could be attained through an improvement in N efficiency. The objective of this study was to determine if the predicted reduction in milk yield associated with feeding a low-protein diet to lactating dairy cows could be avoided by dietary supplementation with 1 or more ruminally protected (RP) AA. Fourteen multiparous and 10 primiparous Holstein cows, and 24 multiparous Holstein × Jersey crossbred cows were used in a Youden square design consisting of 8 treatments and 3 periods. The 8 dietary treatments were (1) a standard diet containing 17% crude protein [CP; positive control (PC)], (2) a 15% CP diet [negative control (NC)], (3) NC plus RP Met (+M), (4) NC plus RP Lys (+K), (5) NC plus RP Leu (+L), (6) NC plus RP Met and Lys (+MK), (7) NC plus RP Met and Leu (+ML), and (8) NC plus RP Met, Lys, and Leu (+MKL). Dry matter intake was not affected by treatment. Crude protein intake was lower for NC and RP AA treatments compared with the PC treatment. No detrimental effect was detected of the low-CP diet alone or in combination with AA supplementation on milk and fat yield. However, milk protein yield decreased for NC and +MKL diets, and lactose yield decreased for the +MKL compared with the PC diet. Milk urea N concentrations were lower for all diets, suggesting that greater N efficiency was achieved by feeding the low-protein diet. Minimal effects of treatments on arterial plasma essential AA concentrations were detected, with only Ile and Val being significantly lower in the NC than in the PC diet. Phosphorylation ratios of signaling proteins known to regulate mRNA translation were not affected by treatments. This study highlights the limitations of requirement models aggregated at the protein level and the use of fixed postabsorptive efficiency to calculate milk protein requirements. Milk protein synthesis regulation by signaling pathways in vivo is still poorly understood.     

豆天蛾氨基酸及脂肪酸分析与评价

对豆天蛾幼虫氨基酸及脂肪酸组成进行了分析测定,结果表明:豆天蛾幼虫含有18种AA和8种EAA,EAA/TAA为53.34%,属于优质完全蛋白质昆虫。豆天蛾幼虫不饱和脂肪酸含量61.74%,其中亚麻酸和油酸的含量较高,亚麻酸含量高达34.11%;饱和脂肪酸含量36.43%,其中棕榈酸的含量较高。     

复合氨基酸锌、铁螯合物的制备及抗菌和抗氧化性研究

通过水体系合成法由8种人体必需氨基酸制备复合氨基酸锌和复合氨基酸铁,利用试管二倍稀释法测定其对菌株Lysinibacillus macrolides、Bacillus cereus、Bacillus subtilis、Staphylococcus aureus、Pseudomonas aeruginosa、Es-che...     

Casein synthesis is independently and additively related to individual essential amino acid supply

Specific AA affect rates of milk protein synthesis in the mammary glands of lactating cows. The objective of this study was to quantify the rate of α_S1-casein synthesis in response to Ile, Leu, Met, and Thr supplementation, and to test the single-limiting AA theory for milk protein synthesis by exploring interactions among these AA. Effects of Ile, Leu, Met, and Thr were studied in vitro with a composite design containing a central point repeated 4 times, with 2 axial points per AA and a complete 2⁴ factorial. Other AA were at the concentration in Dulbecco's modified Eagle medium/F12 medium (DMEM). The experiment was replicated with mammary tissue from 5 lactating cows. Mammary tissue slices (0.12 ± 0.02 g) were incubated for 4 h at 37°C in 5 mL of treatment medium containing ²H₅-Phe. Caseins were precipitated from cell homogenate supernatants. Enrichment with ²H₅-Phe of the N[34]LLRFFVAPFPE α_S1 peptide was determined by matrix-assisted laser desorption/ionization-tandem time-of-flight (MALDI-TOF-TOF), which was used to determine enrichment of Phe in the transfer (t)RNA pool and α_S1-casein fractional synthesis rates (CFSR). Data were analyzed with a polynomial mixed model containing linear, quadratic, and 2-factor interactions for Ile, Leu, Met, and Thr, and cow and residual as random factors. Interactions were not significant at P < 0.1 and were removed from the model. Increasing concentrations of Ile, Leu, Met, and Thr simultaneously increased CFSR curvilinearly with a predicted maximum response of 4.32 ± 0.84%/h at 63% of DMEM concentrations. The maximum response to each of the 4 AA was at 71, 49, 60, and 32% of the concentration in DMEM, for Ile, Leu, Met, and Thr, respectively. These values correspond to 270, 120, 440, and 140% the plasma concentrations of Ile, Leu, Met, and Thr observed in lactating cows fed to meet National Research Council requirements, respectively. The CFSR estimated at those maxima were similar among AA (3.6 ± 0.6%/h). Individual AA effects on CFSR did not correlate with mammalian target of rapamycin (mTOR) signaling. Independent responses of CFSR to individual essential AA observed in this study contradict the single-limiting AA theory assumed in current requirement systems. The saturable responses in CFSR to these 4 AA also highlight the inadequacy of using a fixed postabsorptive AA efficiency approach for determining AA requirements for milk protein synthesis.