Vascular sources of phenylalanine, tyrosine, lysine, and methionine for casein synthesis in lactating goats

The contribution to casein biosynthesis of peptides derived from blood was examined in late lactation goats (254 to 295 d in milk). Ratios of mammary uptake of free amino acids (AA) in blood to output of AA in milk protein and ratios of the enrichments of Phe, Tyr, Met, and Lys at isotopic plateau in secreted milk casein to the free AA in arterial and mammary vein blood were monitored during the last 5 h of a 30-h continuous i.v. infusion of [1-13C]Phe, [2H4]Tyr, [5-13CH3]Met, and [2-15N]Lys on two occasions: before (control) and on d 6 of an i.v. infusion of Phe (6 g/d). During the control, uptakes of free Phe and Met were less than their output in milk. This result was comparable with the labeling kinetic results, suggesting that vascular peptides contributed 5 to 11% of Phe and 8 to 18% of Met. Free Tyr and Lys uptakes during the control were sufficient for milk output; however, the labeling kinetics indicated that 13 to 25% of the Tyr and 4 to 13% of the Lys were derived from peptides. Infusion of Phe increased the uptake of free AA but reduced the contribution of peptides toward Phe (0 to 3%) and Tyr (8 to 14%) supply for casein synthesis. Whole body hydroxylation of Phe to Tyr increased from 10 to 18% with the infusion of Phe; within the mammary gland, this conversion was lower (3 to 5%). Results suggest that the mammary utilization of peptides containing Phe and Tyr appears to depend on the supply of free AA in blood.     

Comparison of the antioxidant and pro‐oxidant activities of broccoli amino acids with those of common food additives

The antioxidant and pro‐oxidant activities of broccoli amino acids were compared with those of common food additives. In decreasing order, the data showed that Asp, SMC, GABA, Glu, Gln, Pro, Phe, Leu, Lys, Arg, Asn, Val, Ile, His, Ser, Gly, Orn and Ala, when dissolved in water at concentrations of 0.5 and 0.05 mM , partially inhibited damage to deoxyribose in the presence of ferric‐EDTA and H₂O₂. In contrast, Tyr and Thr acted as pro‐oxidants in this system. The amino acids present in broccoli had no hydrogen peroxide‐scavenging effect. When dissolved in water, methanol or ethanol, SMC, Glu, Thr, Gln, Ser, GABA, Pro, Ala, Ile, Phe, Asp, Orn and Tyr inhibited lipid peroxidation. However, Asn, Val, Arg, Leu, Lys, His and Gly were not effective in decreasing peroxidation at concentrations of 0.5 and 0.05 mM . Asp > SMC > Ala > Phe > Hys > Orn > Gln = Ser > Lys > Leu = GABA = Gly > Tyr > Arg = Thr > Val > Asn > Pro > Ile > Glu (p < 0.025) showed scavenging activity towards hypochlorous acid, protecting α₁‐antiproteinase against inactivation. In this paper it has been established that some amino acids premixed with propyl gallate increase its hypochlorous acid‐scavenging capacity, while other amino acids have an additive effect with propyl gallate, permitting smaller quantities of propyl gallate to be used as food additives in some products which contain these amino acids. © 2001 Society of Chemical Industry     

Bifidobacterial growth–promoting effect of yak milk κ‐casein hydrolysates produced with different proteases

The growth‐promoting effects of κ‐casein hydrolysates produced by four different proteases (trypsin, alcalase, papain and chymosin) on bifidobacteria (Bb12 and BBMN68) viability were evaluated. Results showed that the obtained κ‐casein hydrolysates possessed better property for improving the viability of Bb12 and BBMN68 than native κ‐casein. The bifidobacterium viability and pH drop were dependent on the added hydrolysates. The addition of κ‐casein hydrolysates improved the viability of Bb12 and BBMN68 to a variable extent. The κ‐casein hydrolysate produced with papain (KCHP) is the best for Bb12 and κ‐casein hydrolysate produced with trypsin (KCHT) is the best for BBMN68. Proper amino acid profiles improved the viability of Bb12 and BBMN68. The bifidobacterial growth‐promoting capacity of κ‐casein hydrolysate may be due to its high content of Ala, Met, Tyr, Phe and Arg residues, especially Tyr which is richer in para‐κ‐casein than in casein glycomacropeptide (GMP). In addition, the sialic acid content of κ‐casein hydrolysate produced with the tested proteases did not show a direct relationship with its bifidobacterial growth–promoting effect. The obtained peptides possessed growth‐promoting activity for Bb12 and BBMN68 existed in para‐κ‐casein.     

Effect of micellar structure of casein and its modification on plasmin-induced hydrolysis

Plasmin-induced hydrolysis of casein in milk can lead to many defects including proteolysis, age gelation, and bitterness. The susceptibility of casein to plasmin can be affected by micellar structure and modification of the lysine residues on caseins. Different levels of casein modification and dissociation of the casein micelle structure were achieved through succinylation. Succinylation occurred at residues Lys7, Lys34, Lys36, Lys42, Lys83 and Lys124 in α_S1-casein; Lys80, Lys150, Lys152, Lys158 and Lys165 in α_S2-casein; Lys28, Lys29, Lys32, Lys99, Lys105, Lys107 and Lys113 in β-casein, as identified using liquid chromatography–tandem mass spectrometry. The dissociation of caseins from the casein micelle reduced steric hindrance and made the protein more readily susceptible to hydrolysis by plasmin. However, the formation of succinyl-lysine rendered β-casein unrecognisable to the substrate-binding pocket of plasmin, resulting in a non-linear decrease in level of hydrolysis because of the competitive effect of micelle dissociation.     

撒坝火腿成熟过程中游离氨基酸的变化研究

以云南撒坝火腿为原料,利用氨基酸自动分析仪检测腌制4月到9月股骨与髋骨之间偏腿背侧肌肉游离氨基酸的变化。结果表明肌肉中的游离氨基酸在成熟期间呈现出先增后降的趋势。腌制到7月时各种游离氨基酸含量最大,占同时期产品质量的5.39%,此阶段含量较高的游离氨基酸分别为Glu、Lys、Ala和Ieu,较低的分别为Met、Tyr、His、Asp。整个成熟期间,含量较高的的氨基酸Glu、Lys、Ala、Lys,含量较低的氨基酸是Cys、Pro、Tyr、Arg。不同的游离氨基酸含量可能使干腌火腿产生不同的风味。     

Kinetics of amino acid extraction by lactating mammary glands in control and sometribove-treated Holstein cows.

Studies of mammary arteriovenous difference were conducted on multiparous lactating Holstein cows (n = 21) on d 35, 70, 105, and 126 of lactation to examine kinetic relationships between arterial concentration and mammary gland extraction of AA. Additionally, these cows were paired by previous lactational performance and assigned to bST-treated or control groups to examine the effect of bST treatment on AA concentration and extraction by lactating mammary glands. Treated cows were injected daily with 40 mg of recombinant bST from d 71 through 126 of lactation. Arterial concentrations of Asp, Ser, Asn, Gly, beta-aminoisobutyrate, and Met were increased. Concentrations of Val, Ile, Leu, Phe, Orn, and Lys were decreased in bST-treated cows compared with controls. Increased extractions of Asp and Met by mammary glands in treated versus control cows were correlated positively with treatment-induced changes in arterial concentrations of these AA. However, increased mammary extractions of Arg, cystathionine, Leu, and Lys by bST-treated compared with control cows were not correlated with bST-induced changes in arterial concentrations of these AA. Extractions of Asn, His, Thr, Arg, Tyr, Met, cystathionine, cystine, Ile, Phe, Orn, Glu, Gly, Tau, Cit, Leu, and Val were correlated linearly with arterial concentrations (r2 greater than .15) of each AA. Extractions of Asp, Glu, Ser, Asn, Gly, Gln, Tau, His, Cit, Thr, Pro, Tyr, Val, cystine, Ile, Leu, Trp, Orn, and Lys also were correlated with arteriovenous differences of Met.     

Kinetics of Casein Degradation during Ripening of Fynbo Cheese Salted with NaCl/KCl Brine

First-order kinetics with respect to the α_s1-casein concentration was used to study casein degradation during low-fat Fynbo cheese ripening. Effects of partial NaCl replacement by KCI during cheese salting were studied by statistical treatment of the casein degradation results. Four zones from cheeses at 1, 5, 10, 20, and 30 ripening days were analyzed by a polyacrylamide gel electrophoresis method. Similar kinetic parameters were obtained for a cheese salted with a NaCl/KCl brine and for a control cheese during ripening. Results were more affected by salt concentration than by salt substitution. KCl did not strongly influence kinetics of Fynbo cheese proteolysis.     

Determination of kinetic parameters for casein hydrolysis by chymotrypsin using two ranges of substrate concentration

Hydrolysis of casein by chymotrypsin was performed at low and high substrate concentrations. Hydrolysis kinetics were analysed in the framework of a two-step model, with consecutive demasking and hydrolysis steps. This model took into consideration the limited accessibility of peptide bonds for the enzyme (masking effect). Dependence of the logarithm of the hydrolysis rate via degree of hydrolysis was non-linear at concentrations of 0.04 and 10 g L⁻¹. In the intermediate range of substrate concentrations (0.07–0.72), this dependence was found to be linear, corresponding to the exponential model of proteolysis. Taking into consideration the multiplicity of peptide bonds, coupled to peptide bond demasking, allowed determination of two important parameters: the ratio of the rate constants of demasking and hydrolysis (k_d/k_h), and the fraction of initially masked bonds (m). An analytical procedure was suggested for the calculation of the apparent Michaelis constants at various degrees of hydrolysis.     

SUBUNIT STRUCTURES AND ESSENTIAL AMINO ACID RESIDUES OF WHITE KIDNEY BEAN (PHASEOLUS VULGARIS) α-AMYLASE INHIBITORS

Both white kidney bean α-amylase inhibitors WKB 858A (MW 42,000) and WKB 858B (MW 20,000) were composed of two subunits as determined by N-terminal amino acid analysis by amino acid sequence, by SDS-PAGE and by separation on a chromatofocusing column in 8 M urea. N-Terminal amino acids for Inhibitor WKB 858A were alanine and glycine, with a sequence of H₂N-Ala-Glu-Asn-Ala-Gly-Thr-Tyr–COOH for deglycosylated 9,000 MW peptide and H₂N-Gly-Asn–COOH for deglycosylated 12,000 MW peptide. N-Terminal amino acids for Inhibitor WKB 858B were alanine and serine, with a sequence of H₂N-Ala-Thr-Glu-Thr-Ser–COOH for the deglycosylated 9,000 MW peptide and H₂N-Ser-Ala-Val-Gly-Leu-Asp-Phe-Val-Leu-Val-Pro-Val-Gin-Pro-Glu-Ser-Lys-Gly-Asp-Thr-VaVal-Glu-Phe-Asp–COOH for the deglycosylated 15,000 MW peptide. Chemical modification of 2 of 7 His residues with diethylpyrocarbonate resulted in 26% loss of inhibitory activity. Modification of 1.5 of 7 Trp residues with N-bromosuccinimide gave 60% loss of inhibitory activity. Modification of 2 of 6 Tyr residues with N-acetylimidazole gave 60% loss of inhibitory activity. Modification of 3.6 of 6 Arg residues with p-hydroxyphenylglyoxal gave 64% loss of inhibitor activity. These results indicate the possible importance of one or more His, Trp, Tyr and perhaps Arg residues for inhibitory activity against porcine pancreatic α-amylase.     

Vascular sources of amino acids for milk protein synthesis in goats at two stages of lactation

An arteriovenous technique, combined with a 30-h i.v. infusion of [5-(13)CH3]Met and [5,5,5-(2)H]Leu, was used to monitor mammary uptake of free amino acid (AA) and to estimate the proportion of casein synthesized from circulating peptides in goats in early and late lactation. At both stages, kinetics was performed on the last day of consecutive 5.5-d periods. The first period was an i.v. infusion of saline and the second an i.v. infusion of lysine (8.9 g/h) plus methionine (2 g/h). Net uptake of essential AA and protein yields were higher in early than in late lactation. Uptake of free Met, His, and Pro was less than, uptake of Tyr and Lys was equal to, and uptake of Arg, Leu, Val, and Ile was greater than milk protein synthesis. Peptide uptake, estimated from the difference in casein and plasma free AA enrichment, accounted for a larger fraction of casein-Met (17 vs. 8%) and casein-Leu (27 vs. 12%) in late than in early lactation. Small decreases in mammary blood flow, AA transport activity, and AA concentrations accounted for the lower uptake of AA in late compared with early lactation. Based on our studies of several AA, the utilization of circulating peptides for casein synthesis appears to be a general phenomenon.     

苦苦菜发酵过程中主要发酵菌种及滋味物质的变化

以苦苦菜为原料进行腌制,对自然发酵的苦苦菜进行菌种分离鉴定和总酸度、pH及盐度的测定。游离氨基酸含量用氨基酸自动分析仪分析,并按其味觉强度进行分类。结果表明:苦苦菜发酵初期以植物乳杆菌为优势乳酸菌,呈味氨基酸中苦味氨基酸(Leu、Val、Arg、Ile、Trp、Met)含量较高。主发酵期以植物乳杆菌和短乳杆菌为优势菌群,甜味氨基酸(Ser、Thr、Gly、Ala、His、Pro)和鲜味氨基酸(Glu、Asp、Lys)的含量逐渐增加,而苦味氨基酸含量逐渐降低。发酵后期以发酵乳杆菌为优势乳酸菌,甜味和鲜味氨基酸含量均高于苦味氨基酸。整个发酵过程中芳香族氨基酸(Tyr、Cys、Phe)含量较低且变化不大,发酵中后期7~20d苦苦菜的滋味最好。     

四川牦牛、黄牛主要品种肉的营养成分分析

对四川牦牛、黄牛主要品种肉的营养成分进行分析,采用相关国标法测定3～4 岁的宣汉黄牛、平武黄牛、川南黄牛、峨边黄牛、九龙牦牛和麦洼牦牛粗蛋白、粗脂肪、矿物质及氨基酸等肉质成分,应用SPSS 对数据进行多变量方差分析和LSD 多重比较。结果显示：不同品种的牦牛、黄牛的肉营养成分(铜、组氨酸除外)存在显著(P ＜ 0.05)或极显著(P ＜ 0.01)差异,且麦洼牦牛、九龙牦牛和宣汉黄牛均具有多方面优良的肉质特性。结论：麦洼牦牛肉粗蛋白,钙、磷、铁、锰和锌元素,缬氨酸、精氨酸、亮氨酸、异亮氨酸4 种必需氨基酸和半胱氨酸等较高;九龙牦牛肉锰、锌元素以及甘氨酸、丙氨酸、脯氨酸3 种非必需氨基酸和苏氨酸、精氨酸等含量较高;宣汉黄牛肉粗脂肪、磷和锌元素以及天冬氨酸、丝氨酸、谷氨酸、丙氨酸、甲硫氨酸、酪氨酸6 种非必需氨基酸,赖氨酸、苯丙氨酸、组氨酸3 种必需氨基酸,必需氨基酸总量和氨基酸总量含量较高。     

Effects of graded levels of duodenal infusions of leucine on mammary uptake and output in lactating dairy cows

Four multiparous Holstein cows, each equipped with a duodenal cannula and an ultrasonic mammary blood flow probe, were assigned to a 4x4 Latin square to measure the effects of duodenal infusions of Leu (0, 40, 80 and 120 g/d) on lactational responses and mammary metabolism of nutrients. Cows were fed a diet of 67.0% corn silage, 5.3% grass hay, 14.2% peas, 7.8% maize starch, 1.0% each of molasses, urea, and sodium bicarbonate and 2.4% minerals and vitamins. Requirements of the remaining 9 essential amino acids were met by infusing into the duodenum 323 g/d of a mixture of amino acids including, Ile, Val, Met, Lys, Trp, Phe, His, Thr, Arg, Tyr and Glu. Milk protein content and yield were highest with 40 g/d of Leu and then progressively declined. Milk fat content and yield were significantly decreased over the entire range of Leu infusions. Arterial concentrations of Leu increased linearly and corresponding mammary arterio-venous differences increased to a plateau with 80 g/d of Leu. As Leu infusions increased, extraction rates of Leu decreased linearly, whereas those of Ile, Val, Lys, Arg, Thr and Tyr were significantly increased. Leu was taken up by the mammary gland according to milk output with 0 and 40 g/d of Leu infused and then largely in excess. Based on responses of protein yield and mammary uptake to milk output ratio, Leu concentration in total amino acids absorbed in the small intestine needs to be close to 8.9% for optimal milk protein synthesis.     

IDENTIFICATION OF ANGIOTENSIN I-CONVERTING ENZYME INHIBITORY PEPTIDES DERIVED FROM THE PEPTIC DIGEST OF SOYBEAN PROTEIN

Peptidic fractions which inhibit angiotensin I‐converting enzyme (ACE) were separated from peptic digests of soybean by ion exchange chromatography and gel filtration. Further separation of the peptidic fractions by ODS HPLC afforded active peptides, the amino add sequences of which were identified by Edman's procedure as: Ile‐Ata (inhibitory against ACE with an IC₅₀of 153 μM), Tyr‐Leu‐Ala‐Gly‐Asn‐Gln (14 μM), Phe‐Phe‐Leu (37 μM), Ile‐Tyr‐Leu‐Leu (42 μM), and Val‐Met‐Asp‐Lys‐Pro‐Gln‐Gly (39 μM). The antihypertensive activity of the soybean peptides was also investigated. Peptide fractions (2.0 g/kg body weight, oral administration) markedly towered the blood pressure of spontaneously hypertensive rats (SHRs).     

Dyeing kinetics of acid dyes onto soybean/casein/polyvinyl alcohol and soybean/polyvinyl alcohol blend fibers

Abstract

Two acid dyes C.I. Acid Blue 113 and C.I. Acid Blue 168 were applied to soybean/casein/polyvinyl (SCP) alcohol blend fibers and soybean/polyvinyl (SP) alcohol blend fibers, and the dyeing kinetics of two fibers were compared. Three kinetic equations, namely Chrastil, Cegarra-Puente and Vickerstaff, were used to fit the experimental dyeing rate points, showing that the best result was obtained by the Chrastil equation. Due to the ratio of acidic amino acids and basic amino acids for SCP was lower than SP fibers, the amino group amount of SCP fibers was higher than that of SP fibers. So SCP fibers displayed slightly higher dyeing rates and dye adsorption values at equilibrium stages than SP fibers. Furthermore, the dyeing of SCP fibers exhibited lower activation energies and higher dyeing rate constants than that of SP fibers and therefore showed slightly lower dependence on temperature.     

ENZYMATIC PROPERTIES OF A PROTEASE FROM THE HEPATOPANCREAS OF SHRIMP, PENAEVS OMENTAIM

The protease purified from hepatopancreas of shrimp, Penaeus orientals, had high proteolytic activity in the pH range of 7.0 to 9.5. Temperature optimum for hydrolysis of casein was 70C. The protease was stable at neutral and alkaline pH and unstable at acidic pH. The apparent Michaelis‐Menten constant (K_m) and the turnover number (V_max) of the protease on hydrolysis of N‐CBZ‐L‐tyrosine p‐nitrophenyl ester (CBZ‐Tyr‐NE) and N‐CBZ‐L‐phenylalanine p‐nitrophenyl ester (CBZ‐Phe‐NE) ‐were similar, however, those for N‐CBZ‐L‐cysteine p‐nitropher.yl ester (CBZ‐Cys‐NE) were different. K_m and V_max for hydrolysis of casein by the protease were determined to be 0.31% and 5.21s^‐1, respectively. The N‐terminal sequence of the protease showed higher homology with the collagenase of crab and trypsins from Crustacea. Myosin heavy chain (MHC) was the primary substrate during proteolysis with the protease. Actin/tropomyosin were degraded progressively during 2 h incubation but to a lesser extent than MHC.     

氨基酸对植物乳杆菌KLDS1.0391生长及细菌素合成的影响

为探究氨基酸对植物乳杆菌生长及细菌素合成的影响，调节化学成分确定培养基中的氨基酸组成，培养植物乳杆菌KLDS1.0391，采用高效液相色谱法测定乳酸含量，通过实时聚合酶链式反应（real-time polymerase chain reaction，real-time PCR）分析细菌素和氨基酸合成相关基因的表达。结果表明，天冬氨酸、组氨酸、异亮氨酸、亮氨酸、脯氨酸、苏氨酸、酪氨酸、天冬酰胺及谷氨酰胺的缺失导致该菌生长能力和细菌素合成量均显著降低（P＜0.05）；谷氨酸、甘氨酸、丙氨酸、半胱氨酸、精氨酸、苯丙氨酸、丝氨酸、色氨酸及缬氨酸的缺失仅影响菌体生长，对细菌素合成无明显影响；而赖氨酸胁迫（缺失及过量）对菌体的生长影响很小，但却显著影响细菌素的合成。色谱结果显示，赖氨酸、酪氨酸、异亮氨酸、亮氨酸、甲硫氨酸、天冬氨酸、天冬酰胺、脯氨酸及苏氨酸单缺失后乳酸含量升高。real-time PCR结果表明，细菌素合成相关基因plnEF、plnD及plNC8HK因赖氨酸的缺失表达显著下调（P＜0.05），而上述基因在外源赖氨酸质量浓度达到2.0 g/L前，上调水平随赖氨酸添加量的增大而增大。氨基酸合成关键基因dapG、yclM 因赖氨酸缺失表达显著上调，相反，上述基因在赖氨酸质量浓度为2.0 g/L时表达量显著下调（P＜0.05）。由上述研究结果推测，当赖氨酸缺失时，菌体通过上调基因dapG 和yclM 的表达以合成多种蛋白质保证其正常生长代谢，赖氨酸可正向诱导该菌细菌素合成，其可能作为细菌素合成底物发挥作用。     

普洱茶晒青样游离氨基酸和色泽差异研究

为探讨游离氨基酸和色值在普洱茶晒青样产地及古树茶和台地茶中的差异,分析了来自云南西双版纳州、临沧市普洱茶晒青样中18 种游离氨基酸组分含量,用色差仪测定茶汤色值（L*、a*、b*）,并进行方差分析、主成分分析。结果表明：晒青样中游离氨基酸组分含量在两地间有明显差异,西双版纳样品中茶氨酸、天冬氨酸、谷氨酸、精氨酸等主要鲜味氨基酸含量高于临沧样品。氨基酸主成分分析对西双版纳和临沧晒青样可以很好区分。台地茶游离氨基酸总量、天冬氨酸、谷氨酸、茶氨酸、组氨酸含量均比古树茶高,精氨酸含量比古树茶低,其中氨基酸总量、谷氨酸、精氨酸、组氨酸差异显著,二者也是在主要鲜味氨基酸上存在差异。两地晒青样汤色存在差异,西双版纳样品L*、b*值较临沧大,a*值较小。古树茶与台地茶汤色差异不明显。     

风鹅现有工艺加工过程中品质的变化规律

通过对风鹅现有工艺加工过程中pH值、色泽、盐分含量、水分含量、硫代巴比妥酸还原物(thiobarbituric acidreactive substance,TBARS)值、总氮含量、非蛋白氮含量、游离氨基酸含量和游离氨基酸态氮含量等指标的测定,研究风鹅肌肉中品质变化规律及脂肪氧化和蛋白质水解可能对风味产生的影响.结果表明,盐分含量在加工过程中不断上升,水分含量不断下降;pH值和TBARS值在一定范围内波动;总氮含量、非蛋白氮含量、游离氨基酸含量、游离氨基酸态氮含量变化差异显著,风干结束后风鹅肌肉中蛋白质水解指数约为3.8％,游离氨基酸含量占非蛋白氮含量的78％以上,含量最多的游离氨基酸含量为Arg、Thr、Glu、Leu和Ala等,而增加较多的游离氨基酸含量是Asp、Leu、Tyr、Val、Ile和Lys等,大部分游离氨基酸的含量都超过其阈值很多倍,可能对风鹅的风味产生重要影响.     

7种虫草真菌菌丝游离氨基酸的聚类分析和 主成分分析

目的研究虫草真菌菌丝中游离氨基酸的组成、主成分和依据氨基酸的聚类。方法以7种虫草真菌菌丝为原料,以菌丝中游离氨基酸含量为对象,应用聚类分析和主成分分析方法探讨不同虫草真菌菌丝中游离氨基酸的含量和组成规律。结果结果表明,聚类分析将7个样品分为3类;其中蛹拟青霉、蝉棒束孢菌丝聚为一类,古尼拟青霉、粉被玛利亚霉、中国被毛孢、细脚拟青霉菌丝聚为一类,戴氏绿僵菌菌丝单独一类。主成分分析提取的前3个主成分可以代表7个样品中游离氨基酸含量93.901%的信息,第一主成分以缬氨酸、苏氨酸、异亮氨酸、亮氨酸、组氨酸、酪氨酸、甲硫氨酸、天冬氨酸和半胱氨酸的影响为主;第二主成分以丝氨酸、苯丙氨酸和精氨酸的影响为主;第三主成分以脯氨酸、赖氨酸和谷氨酸的影响为主。结论聚类分析将7个样品分为3类,主成分分析提取得到3个主成分。