微波消解技术在氨基酸分析中的应用研究

目的:建立微波消解法应用于氨基酸分析的水解蛋白方法。方法:以米粉、面粉、燕麦粉、油条粉作为研究对象,分别比较了常规酸水解和微波消解法对4种样品前处理后氨基酸测定结果的影响。实验结果表明,微波消解水解蛋白的最佳条件是150℃,15 min;该微波消解法与常规酸水解法无显著性差异。4种样品采用微波消解法水解蛋白质,氨基酸测定结果RSD值均小于5%。结论:微波消解法的稳定性好、用时短,可替代现有的常规酸水解方法,便于快速检测批量样品。     

微波消解法在测定新疆8种葡萄干中氨基酸的应用

用微波辅助提取酸水解葡萄干中的蛋白质,结合日立L-8900型全自动氨基酸分析仪测定了新疆特有8种葡萄干中17种氨基酸的含量和组成,其中属马奶子葡萄干中氨基酸含量最高。试验对微波水解的条件进行了优化,结果表明,160℃、30 min微波水解得到氨基酸含量与传统加热水解(110℃,22~24 h)的结果基本相同,且缩短了水解时间。17种氨基酸的线性范围为1.0~80.0μmol/L,线性回归系数均在0.999以上,该方法检出限在0.06~9.83μg·m L-1之间,加标回收率为81.0%~102.2%。     

广西水牛奶和荷斯坦牛奶中蛋白质和氨基酸的含量及组成分析

目的研究广西区内生水牛奶和荷斯坦生牛奶中蛋白质、氨基酸含量及其组成特性,分析水牛奶和荷斯坦牛奶的差异。方法采用盐酸水解法处理牛奶样品,通过氨基酸自动分析仪测定氨基酸含量,分析水牛奶和荷斯坦牛奶氨基酸的含量和组成;通过凯氏定氮法测定牛奶中蛋白质含量。结果 18份牛奶样品中蛋白质、氨基酸的测定结果表明,生水牛奶的蛋白质和氨基酸含量均高于荷斯坦生牛奶,而水牛奶和荷斯坦牛奶中各氨基酸含量占氨基酸总量的比值相近。结论该方法为广西生水牛奶和荷斯坦生牛奶的鉴别提供参考。     

银鲈对六种饲料原料蛋白质和氨基酸的表观消化率的影响

试验用Cr2O3间接测定法测定了银鲈(Bidyanus Didyanus)对秘鲁鱼粉、国产鱼粉、豆粕、酵母、麦麸、次粉等6种常用饲料原料蛋白质和氨基酸的表观消化率.试验结果表明,银鲈对这6种饲料原料的蛋白质和氨基酸表观消化率均以秘鲁鱼粉和国产鱼粉为最高,分别为86.20%和89.50%,82.53%和88.84%;豆粕和酵母粉次之,分别为76.96%和85.54%,72.93%和84.37%;麦麸和次粉为最低,分别为61.23%和78.20%,68.06%和78.67%.由此可得出,银鲈对动物性蛋白原料(秘鲁鱼粉、国产鱼粉)的蛋白质和氨基酸的表观消化率均高于植物性蛋白原料(豆粕、麦麸、次粉)和单细胞蛋白原料(酵母),且差异显著(P<0.05).     

微波对螺旋藻蛋白质酶解促进作用的研究

利用微波对螺旋藻溶液进行预处理,然后用蛋白酶进行水解试验,使蛋白质转化成为氨基酸。经过单因素试验和正交试验,表明经微波处理后的螺旋藻蛋白质水解率得到明显提高,并且得出微波辅助螺旋藻酶促水解的较优工艺参数。     

蛋白质水解度的测定

介绍了一种新的测定蛋白质水解度的方法,该方法利用待测蛋白样品完全水解液做为茚三酮比色的标准样品测定蛋白质的水解度,并和常用的几种测定水解度的方法进行了比较,该种方法消除了由一种氨基酸做为对照样品所带来的测定误差,是一种简易行的测定水解度的方法。     

食品中多环芳烃残留分析前处理方法的研究

文中设计并比较了水解-液液萃取法、水解-微波辅助萃取法、微波辅助萃取-水解法和水解一超声波萃取法4种食品中多环芳烃(PAHs)残留分析的提取方法;同时进行了净化实验。结果表明,水解-液液萃取法和水解-微波辅助萃取法的提取效果理想;采用中性氧化铝固相萃取回收率高,除杂效果明显。将水解-微波辅助萃取-中性氧化铝固相萃取净化法应用于多种食品进行分析,结果表明该方法适用于食品中PAHs残留分析。     

银鲈对六种饲料原料蛋白质和氨基酸的表现消化率的影响

试验用Cr2 O3间接测定法测定了银鲈 (BidyanusDidyanus)对秘鲁鱼粉、国产鱼粉、豆粕、酵母、麦麸、次粉等 6种常用饲料原料蛋白质和氨基酸的表观消化率。试验结果表明 ,银鲈对这 6种饲料原料的蛋白质和氨基酸表观消化率均以秘鲁鱼粉和国产鱼粉为最高 ,分别为 86 .2 0 %和89.50 % ,82 .53 %和 88.84% ;豆粕和酵母粉次之 ,分别为 76 .96 %和 85 .54 % ,72 .93 %和 84.37% ;麦麸和次粉为最低 ,分别为 61 .2 3 %和 78.2 0 % ,68.0 6 %和 78.67%。由此可得出 ,银鲈对动物性蛋白原料 (秘鲁鱼粉、国产鱼粉 )的蛋白质和氨基酸的表观消化率均高于植物性蛋白原料 (豆粕、麦麸、次粉 )和单细胞蛋白原料 (酵母 ) ,且差异显著 (P <0 .0 5)。     

微波水解-茚三酮柱后衍生离子交换色谱法测定鹌鹑蛋中的17种氨基酸

目的建立微波水解茚三酮柱后衍生离子交换色谱法同时测定鹌鹑蛋中17种氨基酸含量的分析方法。方法采用磺酸型阳离子树脂离子交换柱分离,茚三酮溶液作为柱后衍生剂,紫外可见分光光度检测器进行检测,检测波长为570nm和440nm,并对微波水解时间及温度进行条件优化。结果 17种氨基酸在一定范围内呈良好线性关系,相关系数均大于0.99;检出限为0.376～0.906mg/L。结果表明,150℃下微波水解20 min的结果与传统加热水解(110℃, 22 h)的效果基本相同。结论该方法分析时间较短,灵敏度较高,可用于鹌鹑蛋中氨基酸含量的检测。     

微波辐射循环降解大豆蛋白反应器的研究

常规蛋白酶水解大豆蛋白质水解时间过长,用微波循环辐射可以缩短反应时间。设计了微波反应器,比较常规蛋白酶水解大豆蛋白中和微波辅助蛋白酶水解大豆蛋白游离氨基酸含量,用甲醛滴定法进行比较,结果分析:经480 W微波辐射60 min胰蛋白酶水解,比常规不用微波胰蛋白水解300 min氨基氮含量还要多。微波辐射不但可以提高反应速率,而且可以提高氨基氮含量。     

Total and ileal digestible tryptophan contents of feedstuffs for broiler chickens

Reliable values of total and digestible tryptophan in components of feed formulation matrices are needed because tryptophan is often the third limiting amino acid in practical poultry diets. However, tryptophan is oxidatively destroyed during acid hydrolysis in routine amino acid analysis and its determination requires a separate analytical procedure. The variability in contents and apparent ileal digestibility for 6‐week‐old broiler chickens of tryptophan in 74 samples representing 24 feedstuffs are presented in this paper. The average ileal tryptophan digestibility coefficient in wheat was 0.83, in sorghum and triticale 0.75, maize 0.71, soybean meal 0.84, sunflower meal 0.81, canola meal 0.78 and cottonseed meal 0.75. Among the grain legumes, tryptophan in lupins was better digested than that in chickpeas, fababeans and field peas. Among the animal protein meals, the tryptophan digestibility coefficients in fish meal (0.77) and blood meal (0.84) were substantially higher than those in meat meal (0.62), meat‐and‐bone meal (0.63) and feather meal (0.52). Marked variations in tryptophan digestibility were also observed among samples of fish meal, meat‐and‐bone meal and meat meal, highlighting significant batch‐to‐batch differences. For most feedstuffs, considerable variability was observed in the tryptophan concentrations, but such variations were not reflected in digestibility coefficients. Copyright © 2006 Society of Chemical Industry     

Blood amino acids and milk composition from cows fed soybean meal, fish meal, or both

Twelve multiparous Holstein cows at 48 +/- 8 d in milk were used in a 4 x 4 Latin square with 21-d periods to determine the effect on feed intake, milk yield, milk composition, and blood amino acids when soybean meal was replaced with fish meal. Fish meal substituted for soybean meal on an isonitrogenous basis at 0, 25, 50, and 100% of supplemental protein. Total mixed diets were (dry matter basis) 25% corn silage, 25% alfalfa hay, and 50% concentrate mix. Intake of dry matter (27.9, 27.8, 26.1, and 25.8 kg/d for diets 1 to 4, respectively) was similar for all diets. Milk yield (37.5, 37.8, 37.2, and 37.7 kg/d) was not affected by diets. Milk protein percentages (3.23, 3.24, 3.31, and 3.35) increased with 100% fish meal supplementation and tended to be higher, with 50% fish meal supplementation compared with 100% soybean meal diet. Milk fat percentages (3.18, 2.99, 3.04, and 2.87) and yields were lower with the 100% fish meal than with the 100% soybean meal diet. Molar proportions of ruminal volatile fatty acids and ammonia were not greatly affected by diet. Fish meal supplementation slightly improved Met status, as shown when blood amino acid data were evaluated. Both extraction efficiency and transfer efficiency of amino acids from the blood by the mammary gland indicated that Met, Lys, and Phe were the most limiting amino acids in all diets. Replacing as much as 50 or 100% of dietary soybean meal with fish meal may improve the amino acid balance and increase the protein content in milk; however, feeding 100% fish meal will likely decrease milk fat percentages.     

Amino acid composition of Brazilian surubim fish (Pseudoplatystoma coruscans) fed diets with different levels and sources of fat

Surubim (Pseudoplatystoma coruscans) is a river fish from the Brazilian São Francisco basin which presents a great potential for commercialization. The amino acid composition of carcasses of surubim fed isoproteic diets with variable levels and sources of fat were determined. The increase of soybean oil at levels of 4%, 8% and 12% in the rations promoted a corresponding increase in nitrogen fixation in the fish carcass, reflected by higher amino acid contents. However, the application of 12% added amounts of pig lard, corn oil, linseed oil or soybean oil, as different sources of fat, did not promote much variation in the fish amino acid fixation. The determination of the essential amino acid composition in the fish carcasses and the A/E ratios of individual amino acids provided a pattern of amino acid requirements of surubim fish.     

Effect of dietary soybean meal and fish meal on protein digesta flow in Holstein cows during early and midlactation

Six lactating cows were fitted with ruminal and duodenal cannula to measure protein digesta flow to the duodenum during early and midlactation. Diets were composed of corn grain, corn silage, and orchardgrass hay plus supplemental fish meal or soybean meal. Diets contained 15.5% CP and 20.7 ADF. Cobalt-EDTA and Yb were used as liquid and particulate digesta markers and cytosine was used as microbial marker. Corrected organic matter digestibilities in the stomachs were 48.4, 49.8, 44.9, and 53.2% for fish meal and soybean meal diets and early and midlactation, respectively. Preduodenal degradabilities were 47.2, 65.8, 56.7, and 56.2% for fish meal and soybean meal diets and early and midlactation, respectively. Nitrogen recoveries at the duodenum were 93.2 and 84.3% for fish meal and soybean meal diets. Intake of amino acids was greater when cows were fed the soybean meal diet, but total flows of amino acids to the duodenum were similar for both diets. Greater quantity of protein escaping ruminal degradation in cows fed fish meal compared with soybean meal was counterbalanced by less microbial synthesis in the rumen.     

响应面法优化元宝枫籽粕酶解工艺及多肽功能特性研究

本文以元宝枫籽粕为原料,采用碱性蛋白酶法对元宝枫籽粕进行酶解,以酶解时间、加酶量、pH、酶解温度、料液比为考察因素,酶解多肽得率为评价指标,在单因素实验的基础上,根据Box-Behnken中心组合实验设计对元宝枫籽粕碱性蛋白酶酶解多肽制备工艺进行优化,并对优化工艺获得的酶解多肽进行了氨基酸组成、吸水性、吸油性、起泡性质、乳化性质和表面疏水性等功能特性表征。结果表明:最优的酶解制备工艺为:酶解时间3.3 h,pH为10,加酶量为3%,酶解温度为55 ℃。在最优制备工艺条件下元宝枫籽粕碱性蛋白酶酶解多肽得率为40.13%±0.15%。氨基酸组成分析表明酶解多肽所含八种必需氨基酸量高达20.3%,远高于国际粮农组织所建议成人所需必需氨基酸量。此外,酶解多肽的吸油性（4.553 g/g）高于大豆蛋白（2.61 g/g）,其表面疏水性（1365.3）与大豆7S球蛋白的表面疏水性相似,乳化性和乳化稳定性略低于大豆分离蛋白。本研究所获得的元宝枫籽粕碱性蛋白酶酶解多肽具有较好的功能特性,这也表明它可作为一种潜在的功能成分应用于食品中,为元宝枫籽粕的新应用开发提供数据和理论支撑。     

固态发酵豆粕的不同生产工艺及其营养品质比较

以米曲霉和植物乳杆菌WZ011为发酵菌种,研究了5种不同的固态发酵豆粕生产工艺及其营养品质。以灰分、粗蛋白量、可溶性蛋白量、游离总氨基酸量、氨基酸含量分布、酸溶性蛋白量、小肽含量、还原糖量、氮溶指数、蛋白分子量、脲酶含量、胰蛋白酶抑制因子含量以及体外消化率为指标,对发酵豆粕营养品质进行了比较和分析。结果表明,米曲霉单菌发酵后,高温水解处理对豆粕营养品质的提高有效,但在米曲霉和植物乳杆菌WZ011的双菌串联发酵过程中增加高温水解处理反而不利。在米曲霉有氧发酵后直接接种植物乳杆菌WZ011进行厌氧发酵条件下所得的豆粕营养品质最优,其中的胰蛋白酶抑制因子含量比原豆粕减少了91.8%,并含有小肽8.01%、乳酸4.95%、γ-氨基丁酸0.317 mg/g以及植物乳杆菌活菌数1.93×1010CFU/g。优化的豆粕发酵工艺操作简单且无污染,其产品富含营养。该工艺在饲料加工行业和养殖业具有应用意义。     

酶解-发酵法制备鱼鲜汁的工艺优化

本文以鲐鱼为原料,利用单因素和正交试验,优化了酶解-发酵法制备鱼鲜汁的工艺,并对其进行了理化指标和微生物检测,以及氨基酸和生物胺测定,从而对产品的营养性和安全性进行了分析。结果表明:原料采用中性蛋白酶/风味蛋白酶（1:2,w/w）,酶添加量800 U/g(w/w),固液比1:4(w/v),50 ℃下酶解6 h后,水解度为69.67%±0.47%;并在此条件下,加入米曲霉制作的豆粕曲（14%,w/w）,加食盐（9%,w/w）,40 ℃下恒温发酵21 d,此条件下所得的发酵液呈红褐色,具有鱼味调味品固有香气及味道,氨基酸态氮含量达0.81±0.02 g/100 mL。发酵液中鲜味氨基酸Asp和Glu,占比27.20%;必需氨基酸占比44.95%;组胺含量仅为13.35 mg/L。该发酵液可作为调配鱼露或其它海鲜调味品的基料,试验为鲐鱼的加工利用提供一条新的途径,具有较好的开发前景和市场预期。     

去盲肠公鸡对豆粕氨基酸标准消化率的比较研究

在比较分析无氮日粮法(NFD)和回归法(REG)测定去盲肠公鸡的内源氨基酸基础损失量(EAALb)的基础上,采用排空-强饲代谢试验测定豆粕的氨基酸(AA)标准消化率,为家禽饲料原料AA营养价值的评定提供理论依据。结果显示:(1)总AA的排泄量(mg/kg DMI)与摄入量(mg/kg DMI)间线性回归方程为Y=12 625.2+0.096X(R~2=0.759);(2)NFD法和REG法测定的EAALb分别为11 489.7、12625.2 mg/kg DMI,两者间差异不显著(P0.05);(3)豆粕总AA的表观消化率随日粮粗蛋白质(CP)水平的增加呈二次曲线变化规律,在CP12.0%时,达到相对恒定;经NFD和REG校正后得到的豆粕总AA标准消化率差异不显著(P0.05),且均不依赖于日粮CP水平,分别介于85.58%~89.61%和86.75%~90.05%。以上结果表明,NFD和REG均可用于测定EAAL_h,豆粕总AA和大部分AA的标准消化率不受日粮CP水平的影响,表明以豆粕AA标准消化率配制日粮具有较好的可加性。     

Effects of ruminal exposure on the amino acid profile of heated and formaldehyde-treated soybean meal

Rumen cannulated Holstein steers, fed corn silage and a corn-soybean grain mixture twice a day, were used to compare the effectiveness of heat and formaldehyde treatments in preserving the amino acid profile of soybean meal exposed to ruminal fermentation for 12 h. Formaldehyde treatments were 0, .3, .6, and .9 g/100 g soybean meal. Defatted soybean flakes treated at 250, 250, 215, and 180 degrees C for 30, 20, 20, and 25 min, respectively, and unheated soybean meal comprised the heat treatments. The in situ polyester bag technique was used to obtain estimates of ruminal degradation of the treated and untreated soybean meals and to obtain undegraded residues from the soybean meals following 12 h of rumen exposure. Diaminopimelic acid was used to assess the extent of bacterial contamination. Significant amounts of apparent diaminopimelic acid were detected in unexposed samples (2.0 to 7.6% of soybean nitrogen) and in residues (4.8 to 12.7% of residue nitrogen). Significant differences in amino acid contents were detected between untreated and heat-treated soybean meals and their respective residues. Formaldehyde treatment was effective in preserving the original amino acid profile of soybean meal.     

The preparation of protein hydrolysate from defatted coconut and soybean meals.

Protein hydrolysate prepared from defatted soybean meal and coconut meal using acid hydrolysis under different conditions were analysed and subjected to sensory evaluation. Analysis of amino acid after hydrolysis showed a 10.32% reduction in the soybean product and a 31.93% reduction in coconut product. Chemical analyses showed similarities in pH, viscosity, salt content and reducing sugar between the hydrolysates and the commercial soy sauce sample. Both amino and total nitrogen and acidity were higher in the hydrolysate than the commercial sample.
Sensory evaluation showed that hydrolysed soybean products gave better scores in terms of colour, aroma, flavour and general acceptability than coconut products. Addition of soybean to coconut meal resulted in improved hydrolysed product.