全脂奶粉中蛋白质和氨基酸组成的比较研究

利用凯氏定氮仪和氨基酸自动分析仪对全脂奶粉中的蛋白质和氨基酸进行分析,测得全脂奶粉中氨基酸总量约占蛋白质含量的95%,各种氨基酸含量占氨基酸总量的比值的极差均小于0.010,氨基酸组成相对稳定,特征氨基酸检测快速、准确,各种分析数据可为建立系统的蛋白质监测技术体系提供理论依据。     

Variation in the composition of barley and its effect on the performance of pigs

The crude protein and basic amino acid contents of 26 samples of barley were determined. The lysine, histidine and arginine contents of barley were positively and significantly related to the crude protein content. The proportion of lysine in barley protein decreased significantly as the crude protein level increased. Differences in the lysine and protein content of barley were shown to affect the growth and carcass quality of bacon pigs.     

Factors influencing rumen microbial growth rates and yields: effect of amino acid additions to a purified diet with nitrogen from urea.

Effects of isonitrogenous urea and amino acid additions upon microbial growth in rumen contents from a cow fed a purified diet in which urea was the sole nitrogen source were studied. Incorporation of amino acids into microbial cells, volatile fatty acids, and carbon dioxide was estimated. Rates of microbial growth, volatile fatty acid production, and effects of amino acids upon microbial nitrogen yields were highest right after feeding and decreased with time after feeding. Microbial growth and amounts of amino acids incorporated into microbial cells, volatile fatty acids and carbon dioxide were related closely to quantity of starch remaining in the rumen. High amounts of starch increased microbial protein synthesis from carbon-14 labeled amino acids and reduced amounts of amino acid fermentation. Estimated microbial protein yields per day were 326.0, 444.4, 497.3, and 527.3 g when 0, 15, 30, and 45 mg amino acid nitrogen replaced urea nitrogen during incubation. Respective values for microbial cells per mole estimated adenosine triphosphate were 15.2, 19.2, 21.0, and 24.5. Microbial cell yields per kg carbohydrate digested were 139.0, 189.5, 212.0, and 224.8 g for 0, 15, 30, and 45 mg amino acid nitrogen. Addition of small amounts of amino acids to a diet containing urea as the sole nitrogen source improved considerably rumen microbial protein yields.     

Amino acids in plasma and duodenal digesta and plasma growth hormone in cows fed varying amounts of protein of differing degradability

Eighty-four Holstein cows in early lactation fed diets varying in protein percent (11, 14, and 17% crude protein) and degradability in the rumen (normal and heated soybean meal) were sampled for effects on amino acids and growth hormone in blood plasma, and amino acid profiles in the duodenal digesta. Essential and branched chain amino acids in plasma increased as protein and amount of protected protein in the diet increased. These changes were accompanied by decreased concentrations of nonessential amino acids. Plasma growth hormone was highest at low protein (11.3%) probably because of decreased intakes on this diet. Molar percentages of amino acids in duodenal contents were not affected by diet suggesting that our heat-treated soybean meal influenced quantity more than quality of amino acids available for absorption in the small intestines.     

团头鲂不同生长阶段肌肉营养成分分析及评价

分析团头鲂（Megalobrama amblycephala）不同生长阶段,肌肉中水解及游离氨基酸组成和含量,并对其营养价值和产品风味进行评价。结果表明：团头鲂肌肉一般营养成分（水分、灰分、粗蛋白、脂肪）随着生长阶段不同并未表现出显著差异,各成分含量基本保持恒定。水解及游离氨基酸含量分别为（7.77±0.79）g/100 g（湿质量）和（0.98±0.10）g/100 g（湿质量）;不同生长阶段未表现出显著性差异。必需氨基酸组成齐全,必需氨基酸占总氨基酸比值为34.62%～38.77%,必需氨基酸与非必需氨基酸比值为70.75%～85.99%。氨基酸评分和化学评分都表明其第一限制氨基酸为甲硫氨酸和胱氨酸。不同生长阶段,团头鲂肌肉中游离氨基酸及其衍生物组成和含量无显著差异,其中牛磺酸含量最高,占游离氨基酸总量的32.04%。     

发芽对糙米蛋白质及氨基酸组成特性的影响

研究了发芽过程中糙米蛋白质和氨基酸含量和组成特性的变化,并与精米和糙米比较,评价了发芽糙米蛋白质的营养价值。结果表明,发芽可以增加糙米蛋白质、总氨基酸和必需氨基酸的含量,必需氨基酸指数提高。发芽过程中清蛋白和谷蛋白含量均呈上升趋势,球蛋白含量呈下降的趋势。除发芽24h外,醇溶蛋白的含量在整个发芽期间也呈现增加趋势,增加的蛋白质主要是谷蛋白。各发芽阶段糙米的必需氨基酸和总氨基酸的比值均大于55%。18种氨基酸中有12种氨基酸的含量在发芽24h最高。发芽后赖氨酸和苏氨酸的含量增加较明显,但仍是限制性氨基酸;丝氨酸、谷氨酸、精氨酸和组氨酸含量均有所增加。发芽24h时EAAI最大,与FAO/WHO模式相比,EAA组成模式更加合理。发芽可以提高糙米蛋白质的营养价值,改善籼稻米的品质,其中以发芽24h为宜。     

四川小麦地方品种营养品质分析

为了评价四川小麦地方品种籽粒蛋白质的营养价值，本文通过化学分析法研究了67个四川小麦地方品种的蛋白质和氨基酸含量及其组成特性。结果表明：蛋白质含量平均为11．86％；18种氨基酸中谷氨酸、脯氨酸、亮氨酸和天门冬氨酸含量丰富，而色氨酸、蛋氨酸和半胱氨酸含量较少；必需氨基酸和总氨基酸含量分别为3．65％和11．68％；必需氨基酸含量与氨基酸总量之比为31．25％；必需氨基酸含量与蛋白质总量之比为30．78％；氨基酸评分表明，赖氨酸和蛋氨酸＋半胱氨酸的氨基酸评分平均值最低分别为47和70，因此赖氨酸和蛋氨酸＋半胱氨酸分别为第1和第2限制性氨基酸；必需氨基酸指数平均值为60。67个小麦地方品种中7个品种其赖氨酸含量相对较高，赖氨酸的氨基酸评分都在60以上；11个品种的必需氨基酸指数较高、均大于65，具有较为平衡的氨基酸组成；13个品种的必需氨基酸含量与氨基酸总量之比超过36％。是蛋白较为优质的小麦品种。结论：与WHO模式比较，四川小麦地方品种中存在部分优质营养品质资源。     

挤压对蛋黄粉性质的影响

采用双螺杆挤压膨化机对蛋黄粉进行加工,研究挤压工艺对蛋黄粉挤压产品色泽、可溶性蛋白质和氨基酸的影响。结果显示,提高进料水分,降低机筒温度,有利于降低挤压蛋黄粉的色差值,并能减少可溶性蛋白质和氨基酸的损失;螺杆转速提高,挤压蛋黄粉的色差值呈总体降低趋势,而可溶性蛋白和氨基酸的含量呈先提高后降低的趋势。     

富硒处理对萌发绿豆中几种营养成分变化的影响

为了解富硒处理对萌发绿豆营养成分的影响,本文以总抗坏血酸、还原糖、可溶性蛋白、游离氨基酸、总膳食纤维这5种营养成分为指标,研究了富硒处理对萌发绿豆中这5种营养成分的含量及其变化的影响.研究结果表明,富硒处理显著抑制绿豆在萌发过程中的总抗坏血酸的合成,对绿豆萌发过程中还原糖的生成有一定程度的影响,但对绿立在萌芽过程中可溶性蛋白,游离氨基酸及总膳食纤维含量及其变化均无显著影响.     

不同熬煮时间对台湾泥鳅汤蛋白组分及抗氧化能力的影响

以台湾泥鳅为研究对象,分析不同熬煮时间(30、60、90、120、150 min)对泥鳅汤蛋白组分和抗氧化能力的影响。结果表明:随着熬煮时间的增加,汤中可溶性蛋白质含量显著(P<0.05)上升,在150 min达到18.49 mg/mL,同时汤中蛋白质水解成不同大小的短肽以及游离氨基酸。泥鳅汤中总游离氨基酸含量、必需氨基酸含量、鲜味氨基酸含量随熬煮时间的增加先上升后下降,在90 min时,总氨基酸含量最高到达2957.2 μg/mL,鲜味氨基酸含量为1296.7 μg/mL。随着熬煮时间的增加,泥鳅汤的ABTS+·清除率和DPPH·清除率均呈上升趋势,尤其是DPPH·清除率在熬煮30~90 min范围内从11.66%上升到84.10%。因此在熬煮90 min时,泥鳅汤的营养品质和抗氧化能力均较好。     

姬松茸和双孢蘑菇固态发酵对小米蛋白质和多酚的影响

采用姬松茸和双孢蘑菇对小米进行固态发酵,并对发酵产物的蛋白质含量和氨基酸组成以及多酚含量进行了测定。结果显示:与未发酵的小米对照相比,姬松茸小米发酵产物和双孢蘑菇小米发酵产物中的粗蛋白、水溶性蛋白和氨基酸态氮含量均得到了显著提高（P<0.05）,其中粗蛋白含量分别提高了6.13%和12.25%,水溶性蛋白含量分别提高了10.37和4.64倍,氨基酸态氮含量分别提高了12.31和1.01倍,且两种小米发酵产物蛋白质的氨基酸评分、必需氨基酸指数（双孢蘑菇小米发酵产物除外）、营养指数以及与鸡蛋蛋白之间的贴近度均高于对照,这说明小米发酵产物的蛋白质质量高于对照;两种小米发酵产物中的游离态多酚和总酚含量显著高于对照（P<0.05）,游离态多酚含量达到3.91和1.57 mg GAE/g DW,分别是对照的4.55和1.82倍,总酚含量达到4.03和1.73 mg GAE/g DW,分别是对照的3.87和1.66倍。本实验结果表明,采用姬松茸和双孢蘑菇对小米进行固态发酵,可以提高小米的蛋白质质量和多酚含量。本实验可以为开发利用小米资源,增加小米附加值提供一定的理论依据,也可为开发利用食用菌资源提供一定的参考。     

新疆伊犁马肉中氨基酸含量测定及分析

利用氨基酸自动分析仪对新疆伊犁马肉进行分析,测定了伊犁马肉中氨基酸的种类和含量,发现伊犁马肉中氨基酸含量丰富,氨基酸总含量为19.91%,所含的人体必需氨基酸占总氨基酸含量的38.5%,基本符合理想蛋白质中人体必需氨基酸标准,而且药效氨基酸含量较高,占总氨基酸含量的68.4%,其中还含有较高含量的谷氨酸、天冬氨酸、亮氨酸和赖氨酸。结果表明伊犁马肉具有很高的营养价值和一定的药用价值。     

豆酱自然发酵过程中蛋白质和氨基酸的变化规律

为研究豆酱在自然发酵过程中蛋白质、氨基酸组成及含量的变化规律,以按照东北豆酱传统方法制作的自然发酵豆酱为研究对象,在检测蛋白质含量、氨基氮含量、氨基酸含量、非蛋白氮含量和水解指数等指标变化的基础上,对豆酱的氨基酸评分(amino acid score,AAS)、化学评分(chemical score,CS)、必需氨基酸指数(essential amino acid index,EAAI)进行分析。结果表明,豆酱蛋白质含量、非蛋白氮含量、蛋白水解指数先上升后下降;氨基氮含量则先不断增加后减少至稳定。自然发酵豆酱中共含有17种氨基酸,但不同发酵时期豆酱中氨基酸含量差异较大,成品豆酱中氨基酸总量维持在41.00 mg/g左右,明显高于生豆粉(11.42 mg/g)和熟豆粉(11.06 mg/g)中氨基酸总量。不同发酵时期豆酱中必需氨基酸与非必需氨基酸的比值在0.48~0.77之间,提示豆酱中的蛋白质为优质蛋白。分析不同发酵时期豆酱的AAS、CS和EAAI可知,发酵20 d时EAAI最高达29.41,发酵50~75 d豆酱的EAAI保持在16.16~17.40之间。通过比较4种呈味氨基酸的含量可知,甜味氨基酸苦味氨基酸鲜味氨基酸无味氨基酸。     

Effect of applying increasing levels of nitrogen to ryegrass: II.—Amino acid composition of peptide and protein fractions

Amino acid concentrations in the peptide fraction of S22 ryegrass increased with total N content but when amino acid N was expressed as percentage of peptide N little variation was noted with increasing maturity or with increasing level of N application. Also under these conditions true protein increased but when expressed as a percentage of total protein N there was little change in the amino acid make-up of this fraction. Total dicarboxylic amino acid N and amide N maintained a 1 : 1 ratio in the peptide fractions under these conditions. Glycine and phenylalanine contents were relatively higher in the peptide fractions, and leucine and valine contents were relatively higher in the protein fractions. Proline content was unusually high in the free state, intermediate in the peptide fraction and lowest in the proteins. The amino acid make-up of the peptide fraction was more closely related to the protein fraction than to the free amino acid fraction and the free amino acids and their amides had some influence in determining the composition of the peptide fraction.     

18种大豆种子蛋白质、氨基酸和脂肪酸的组成成分分析

对18种大豆种子蛋白质和氨基酸、总脂肪及脂肪酸组成进行了分析。结果表明:榆林地区的横山老黑豆和神木连枷条的蛋白质含量较高,山西地区的汾豆79氨基酸含量最高,东北地区的吉育82的总脂肪含量最高;GC-MS共鉴定出7种脂肪酸,其中亚油酸和油酸的含量较高,不饱和脂肪酸的含量均在70%以上,其中子洲小黑豆、靖边黑豆和晋豆19所提取的油中不饱和脂肪酸含量在80%以上。研究结果可为筛选更适合种植的大豆品种提供理论依据。     

迁粉蝶幼虫和蛹的营养成分分析

为了深层次地开发利用迁粉蝶,探寻迁粉蝶幼虫和蛹的主要营养成分,评价它们的营养价值水平,为它们的食用开发提供理论基础。通过运用国家标准检测方法测定迁粉蝶幼虫和蛹的水分、脂肪、蛋白质、矿物质元素、氨基酸的含量,分析其氨基酸分、必需氨基酸指数,并将迁粉蝶幼虫和蛹的蛋白质、氨基酸、脂肪、矿物质元素含量与常见食物中的含量进行比较分析。结果显示,迁粉蝶幼虫和蛹具有高蛋白质(质量分数分别为56.8%和69.0%)、低脂肪(质量分数分别为10.9%和9.9%)、无机物质含量丰富、检测的矿物质元素含量水平高、能量值低等特点;迁粉蝶幼虫和蛹的总氨基酸含量分别为364.4 mg/g和458.1 mg/g,必需氨基酸总含量分别为126.5 mg/g和163.0 mg/g,必需氨基酸占总氨基酸的质量分数分别为34.7%和35.6%,必需氨基酸与非必需氨基酸的比值分别为0.53和0.55,必需氨基酸指数分别为0.83和0.74。表明迁粉蝶具有较高的营养价值和食用开发价值。     

Nitrogen-to-protein conversion factors for some cereal products in Japan

ABSTRACT:  To evaluate a practical method of determining more accurately conversion factors for calculating the protein contents of foods from the total nitrogen content, 19 cereal products found in Japan were analyzed for total nitrogen, amino acid nitrogen, and amide nitrogen, and then the nitrogen-to-protein conversion factors were calculated. The average conversion factors were 5.75 for rice, 5.81 for wheat, and 5.95 for others. These values, corresponding to the proportion of the amino acid residue to amino acid nitrogen recovered from 20 amino acids, were lower than the currently applied factors to these foods, except for wheat flour and amaranth. The use of this factor for estimating the protein content results in a considerable difference from the estimate based on amino acid residue concentrations, due to the wide variations in amino acid composition and to the presence of a significant level of nonprotein nitrogen. The distribution of the protein nitrogen recovered from the amino acids to total nitrogen averaged 93%. Adjusted conversion factors corresponding to the proportion of the amino acid residue to total nitrogen averaged 5.26 for rice, 5.47 for wheat, and 5.54 for other cereal products. Protein contents estimated using these factors are in good agreement with the contents defined as amino acid residues.     

Biological evaluation of mechanically deboned chicken meat protein quality

Mechanically deboned chicken meat (MDCM) is a meat product obtained by crushing tissues after meat removal and is largely used in meat products. Protein quality of flour prepared from defatted MDCM and from fresh chicken breast meat (FCBM) was chemically and biologically evaluated by rat growth and nitrogen balance studies. Proximate chemical composition, on a dry basis, of MDCM and FCBM showed protein contents of 90.5% and 82.2%, lipid contents of 3.0% and 13.2% and ash contents of 6.1% and 4.2%, respectively. There was a relatively good balance of essential amino acids in both samples although lysine was in low concentration in MDCM being a limiting amino acid. Feeding of flour diets resulted in high protein efficiency ratio, a high net protein utilization and high nitrogen balance, thus showing a high biological value and also high true digestibility and, consistently, NPU for both samples is similar to casein.     

煮制过程中食盐引起猪肉汤成分含量变化的研究

本文以煮制30、60、90、120 min猪肉汤为研究对象,通过测定加盐与无盐猪肉汤煮制过程中的蛋白质降解产物含量、性质、分子量分布范围、氨基酸组成、脂肪和脂肪酸含量等变化,分析食盐对猪肉汤成分含量差异性的影响。结果表明,在不同煮制时间下,加盐肉汤中的粗蛋白含量、非蛋白总氮含量、可溶性蛋白氮含量、盐溶性蛋白含量、氨基酸总含量、脂肪含量及脂肪酸总含量等均高于无盐肉汤。加盐肉汤中水解氨基酸总含量为5.897 mg/mL,与肉汤中粗蛋白含量的测定结果趋势一致,每煮制30 min,其盐溶性蛋白含量约增加0.6 mg/mL,且在煮制90 min后,其游离氨基酸含量显著(P<0.05)高于无盐肉汤。根据凝胶电泳图谱分析,食盐的添加使大分子蛋白降解为小分子蛋白,分子量由135~245 kDa向35~48 kDa转移。加盐肉汤中单不饱和脂肪酸含量显著(P<0.05)高于无盐肉汤,其中C18:1含量最高,并在煮制120 min时高达3.763 mg/mL。综上,食盐的添加促进肉汤中蛋白质的溶解、渗出及降解,提高了必需氨基酸占比,并在一定程度上防止不饱和脂肪酸被氧化,有利于被人体吸收和利用。     

变黄期不同温湿度对烘烤中烟叶蛋白质降解及其相关酶活性的影响

为合理调控烟叶蛋白质含量、提高烟叶质量提供理论依据,对密集烘烤不同变黄温湿度烟叶蛋白质降解和蛋白酶、内肽酶、谷草转氨酶、谷丙转氨酶活性的变化关系进行了研究。研究结果表明,烘烤过程中,不同变黄温湿度下烟叶水分、蛋白质、氨基酸及其相关酶活性的变化规律基本一致;水分和蛋白质含量呈下降趋势,氨基酸含量一直增加,蛋白酶和内肽酶活性呈先升高然后降低而后再升高的“双峰曲线”变化;谷丙转氨酶和谷草转氨酶活性在烘烤开始时有小幅度增加,并出现一个小的峰值,然后呈下降趋势,从60h起急剧升高并达到最大值;且内肽酶活性与可溶性蛋白质相关性显著,和游离氨基酸相关性极显著;谷丙转氨酶只和游离氨基酸相关性显著。密集烘烤不同变黄温湿度,低温中湿变黄处理烟叶中性蛋白酶、内肽酶、谷草转氨酶和谷丙转氨酶活性高且作用时间较长,有利于烟叶内蛋白质的降解和氨基酸的合理转化,改善烟叶质量。