Enhanced photostability of monascus pigments derived with various amino acids via fermentation

The photostability of 18 amino acid derivatives from monascus pigment was tested under various physical and chemical conditions. Under sunlight, the half-life of derivatives was increased to 1.45-5.58 h, corresponding to a 6-25-fold improvement over a control red pigment (0.22 h). The degradation of pigment derivatives followed a first-order reaction, and the pigment stability increased with an increasing concentration while it decreased with both an increase and decrease in pH from 7. The stabilities of derivatives decreased in descending order in hexane, ethanol, propanol, methanol, ethyl ether, distilled water, chloroform, and acetonitrile. Pigment stability under UV light (365 nm) showed a pattern similar to stability after exposure to sunlight. After 30 days of incubation at 30 degrees C, more than 80% of the initial derivative contents remained while only 29% of the control red remained. The differences in degradation patterns that control red gradually changed to brown whereas the phenylalanine derivative remained a weak red were confirmed by HPLC analysis.     

玉米直链回生淀粉吸附含羟基红曲红色素的动力学

为了提高玉米回生淀粉通过吸附分离含羟基红曲红色素的效率,深入了解玉米直链回生淀粉吸附含羟基红曲红色素的机理,该文通过回生法制备分子量分布范围分别为267~4.6×10~7、589~9.7×10~4、565~6.2×10~4、794~6.0×10~4 g/mol的玉米直链淀粉,进而利用这些淀粉吸附红曲红色素,研究不同淀粉在20、40、80℃温度下对红曲红色素的吸附量和吸附速度,采用Dubinin-Radushkevich等温吸附方程研究玉米直链回生淀粉吸附含羟基红曲红色素的动力学规律。结果表明,回生1~4次玉米直链回生淀粉在80℃、140 h吸附红曲红色素量最多,吸附量分别达到0.56、0.84、1.04、1.10 mg/g,直链回生淀粉分子量分布范围越窄,吸附温度越高,吸附速度越快。经Dubinin-Radushkevich等温吸附方程式计算所有样品平均吸附自由能低于8 J/g,玉米直链回生淀粉吸附红曲红色素方式为物理吸附。电子显微镜图结果表明,吸附红曲红色素的玉米直链淀粉干燥后结构更加蓬松。研究结果为玉米直链回生淀粉分离、纯化含羟基红曲红色素工艺条件的设计和探索提供理论参考。     

Color and stability of pigments derived from the acetaldehyde-mediated condensation between malvidin 3-O-glucoside and (+)-catechin

A pigment derived from the acetaldehyde-mediated condensation between (+)-catechin and malvidin 3-O-glucoside has been prepared and isolated by semipreparative HPLC, and its characteristics of color and stability have been studied and compared with that of malvidin glucoside in aqueous solutions. When the pH was increased from 2.2 to 5.5, the solution of the pigment became progressively more violet (lambda(max) = 560 nm at pH 5.5), whereas similar solutions of the anthocyanin were almost colorless at pH 4.0. This behavior indicated that the anthocyanin moiety of the pigment was more protected against water attack, and thus the formation of its quinonoidal forms was favored. The color of the pigment also showed more stability with regard to bleaching by SO(2) than that of malvidin glucoside. Nevertheless, the pigment was more sensitive to degradation in aqueous solution than the anthocyanin. The cleavage of the ethyl bridge that links the anthocyanin and the catechin constituted the first step in its degradation, as demonstrated by the formation of malvidin glucoside as a major product.     

植物对氨基酸的吸收利用及氨基酸在农业中的应用

植物对氨基酸的吸收、转运、代谢以及氨基酸在肥料和农药上的应用国内外已有报道。已有研究证明,植物可直接吸收土壤中的氨基酸分子,其吸收后的转运、分配、代谢因氨基酸种类而异,产生的生理效应也不相同;氨基酸农药易被日光分解或被自然界微生物降解,在土壤中、植物体内不留残毒,其降解产物还可作为农作物的营养物质,提高农作物的品质和产量,施用这类农药,人畜安全,没有公害;氨基酸肥具有促进植株生长发育、增强抗逆性、改善土壤状况和提高作物产量的作用。     

Color and antioxidant properties of cyanidin-based anthocyanin pigments

A series of cyanidin-based anthocyanin pigments was investigated to determine the effect of structural variation on a number of chemical and physical properties: CIELAB color coordinates, visual detection thresholds, hydration constants (pK(H)), and in vitro antioxidant activities (ORAC). In addition to individual isolated compounds, purified total pigment isolates from blackberry, elderberry, black carrot, red cabbage, and sweet potato were also examined. Acylation with cinnamic acids shifted color tonality (hue angle) to purple, and markedly increased pK(H) and antioxidant activity, but lowered the visual detection threshold. Glycosidic substitution at the 5 position moved tonalities toward purple and decreased pK(H), and tended to lower the ORAC value, but raised the visual detection threshold. Increasing the number of sugar substituents at the 3 position also affected all of these parameters, however, the extent was not predictable. Antioxidant levels of purified anthocyanin extracts were much higher than expected from anthocyanin content indicating synergistic effect of anthocyanin mixtures.     

Humic acid reactions with amino acids

Reactions between five humic acids extracted from soils with widely differing pedological histories and 17 amino acids commonly occurring in proteins were investigated in aqueous solutions at pH 3.0 and 6.5. The reactions were affected by: (a) nature of the humic acid: (b) pH of the system: and (c) length of contact. The principal reaction appeared to be the microbiological oxidative degradation of the amino acids leading to the formation of substantial amounts of ammonium. While there was no evidence that the humic acids per se interacted with the amino acids, they did not appear to interfere with the microbiological degradation of the amino acids.     

人工神经网络方法在红曲杨梅果酒发酵工艺优化中的应用

将人工神经网络技术与传统正交试验方法相结合，提出一种新的试验数据分析和处理方法，利用神经网络特有的自学习能力，可以充分挖掘正交试验数据信息，并通过仿真、评估和优化，获得了红曲杨梅果酒发酵的最佳工艺：发酵温度18℃、糖汁比4∶6、酵母加量15%、红曲加量2.1%。将该优化工艺应用于实际生产中，取得了较好的效果。     

Differential characteristics of fatty acids in cheese from milk of various animal species by capillary gas chromatography

The kind of milk used in the manufacture of cheese has been identified by analysis of the fatty acids. The milk fat is extracted from the cheese and saponified. The methyl esters of the fatty acids are prepared and determined by capillary column gas chromatography. Seven major fatty acids are separated and quantitated, namely, C8:0, C10:0, C12:0, C14:0, C16:0, C18:0, and C18:1. Many of the 21 simple ratios that can be formed from these 7 quantities are characteristic of the type of milk from which the fatty acids were obtained. The method allows the identification of cheese prepared with the milk of cows, buffalo, sheep, or goats. Substitution or adulteration of milk can also be detected.     

复合氨基酸微量元素螯合肥制备工艺研究

以废弃鸡毛水解液为复合氨基酸来源,研究其与微量元素铁、锌、锰、铜螯合的最佳工艺条件,并利用有机溶剂沉淀分离法制备固体复合氨基酸亚铁、锌、锰、铜螯合物,以螯合率为指标考察影响制备工艺的主要因素。结果表明,最佳工艺参数为:复合氨基酸与亚铁、锌、锰和铜螯合反应的最佳配位体摩尔比均为2∶1;最佳pH值范围分别为5.0、8.0、4.0～5.0和6.0～7.0;反应温度为室温(222～6℃);反应时间为30.min。在上述条件下,复合氨基酸与各微量元素的螯合率均超过95%;所得复合氨基酸螯合物可与0.2.mol/L磷酸二氢钾复配,克服了传统微肥完全不能与磷酸盐复配的缺陷。     

Comparison of humic acids derived from city refuse with more developed humic acids

Abstract

The humic acids (HA) from composted and uncomposted city refuse (CR) were characterized by degradative (oxidation with persulphate and permanganate) and non-degradative techniques (FT-IR and ¹³C-NMR) in order to analyze the effect of the composting process on these HA. They were also compared with commercial HA extracted from leonardite. The carboxyl and carbonyl group content of the HA from CR increased slightly during composting. Since the HA from the composted CR showed a lower N and H content, the FT-IR spectra showed a lower intensity in the bands corresponding to peptides and carbohydrates. Differences were revealed when the HA from both CR were compared with those from leonardite which showed a much lower N and H content and a less aliphatic character. The percentage of degraded products by persulphate was higher for the HA from uncomposted CR. For the HA from both CR the major components among the oxidation products were dicarboxylic acids and normal fatty acids. In the leonardite HA, the major components consisted of benzene polycarboxylic acids. ¹³C-NMR revealed an attenuation of the aliphatic character of the HA from CR with composting.     

Ion-exchange separation of amino acids with postcolumn orthophthalaldehyde detection

Moore's and Stein's classical ion-exchange separation of amino acids remains the standard by which all methods are judged. The adaptation of liquid chromatography (LC) equipment to amino acid analysis was inevitable because microprocessor control of gradients allowed almost infinite variation in gradient shape, producing superior resolution with only 2 buffers. The versatility of LC equipment allowed the instruments to be used for other assays. Adaptation of orthophthalaldehyde (OPA) to amino acid analysis increased detection sensitivity to the picomole range. A method for essential amino acids analysis in mechanically separated red meat and poultry products has been adapted to liquid chromatography using postcolumn hypochlorite oxidation, OPA derivatization, and fluorescence detection. Separation is achieved with 2 sequential concave exponential gradients combining ionic strength and pH increases with halide-containing buffers. Hydroxyproline and proline are detected with increasing sensitivity through the use of 3-mercaptopropionic acid in a stabilized OPA reagent. Sample preparation is a critical part of the method. A defatting procedure removes fat and other nonprotein nitrogenous substances. The hydrolysis procedure is designed to protect tryptophan which can be routinely assayed in hydrolysates with a modified flow program. Corrosion damage to the equipment by halide buffers has brought about a search for alternative methodology.     

Capillary gas chromatographic analysis of amino acids by enantiomer labeling

The optical isomers of amino acids can be easily separated by gas chromatography using capillary columns coated with the chiral polysiloxane peptide, Chirasil-Val. Quantitative trace amino acid analysis in complex mixtures such as biological fluids, sea water, or protein hydrolysates can be achieved by enantiomer labeling: The D-amino acid enantiomers, which do not occur naturally, are added to the sample prior to analysis as internal standards. Because the D-enantiomers show the same physical and chemical properties as the natural L-enantiomers, they are ideal standard references. In routine analysis, the derivatization is achieved with a new automated derivatization robot. The D-standard serves as overall internal standard for the whole analytical procedure from sample enrichment to derivatization, chromatography, and response of the detector.     

氨基酸和壳聚糖对烤烟生理特性及香味品质的影响

本文研究了叶面喷施氨基酸和壳聚糖对烤烟烟叶质体色素含量、酶活性的变异以及对致香物质含量的影响.结果表明:打顶后氨基酸处理烟叶叶绿素、类胡萝卜素、苯丙氨酸解氨酶(PAL)活性和脂氧合酶(LOX)活性较高,壳聚糖处理影响不显著;氨基酸处理的烟叶致香物质均比壳聚糖处理和CK高,尤其是对苯丙氨酸类、美拉德反应产物类影响显著,增幅分别达到20.9%、23.1%.壳聚糖对苯丙氨酸类致香物质有较大提高,增幅为17.6%.从整体上看,氨基酸处理调整了发育后期质体色素组分比例和相关酶类的活性,对烟叶香味品质的影响效果要好于壳聚糖.     

Rapid and sensitive quantification of amino acids in soil extracts by capillary electrophoresis with laser-induced fluorescence

A growing body of research is arguing that amino acids are key components of the soil nitrogen cycle. For example, we now know that many plants can take up intact amino acids, even in competition with soil microbes. Our growing recognition of the importance of amino acids is not matched by knowledge of the amounts and type of amino acids in the soil, certainly not in comparison with our encyclopaedic knowledge of inorganic N. The primary reason that less is known about amino acids than inorganic N is that measuring the amounts of individual amino acids with conventional chromatographic techniques is slow and typically requires extensive sample clean-up if KCl extracts are analysed. The aim of this study was to develop capillary electrophoresis with laser-induced fluorescence detection (CE-LIF) as a more rapid alternative for measuring individual amino acids in KCl extracts of soil. The CE-LIF method separated 17 common amino acids within 12 min, with detection limits between 7 and 250 nM. One molar KCl extracts could be analysed without any sample clean-up or de-salting, and spike and recovery tests indicated that the complex matrix of soil extracts did not affect quantification. Further evidence of the suitability and robustness of the method came from the repeated analysis (n=5) of the same soil KCl extract. The relative standard deviation of migration times for replicate analyses were <0.2% while relative standard deviations for peak areas were <5%. To demonstrate application of the CE-LIF method to real world problems it was used to analyse amino acids in 1 M KCl extracts from a sub-alpine grassland and a Eucalyptus regnans forest. The most abundant amino acids were Ala, Gly and Arg. Other amino acids present at smaller concentrations or in a minority of samples were Asn, Cit, GABA, Glu, His, Phe, Leu, and Lys. The proposed CE-LIF method offers significant advantages over chromatographic methods via its rapidity, reproducibility and, most importantly, its ability to analyse crude KCl extracts.     

Interference by amino acids during the determination of N ammonium in soil

In the study of terrestrial N cycling, NH₄⁺ concentration and ¹⁵N enrichment are routinely determined by colorimetric continuous flow analysis and microdiffusion methods. Amino acids can interfere in these determinations; consequently the aim of the present study was to evaluate the significance of the interference. Glycine and glutamine are key amino acids in soil and were therefore used as ‘models’. Both glycine and glutamine interfered during continuous flow analysis, whereas interference during microdiffusion was of little importance. The effects of interference can be significant, e.g. estimates of gross mineralisation rate were reduced up to 33%, where we allowed for amino acid interference during determination of NH₄⁺ concentration. The potential influence of amino acid interference emphasises that development of continuous flow analysis to increase NH₄⁺ specificity is needed.     

Analysis of amino acids by gas chromatography as the N-trifluoroacetyl n-butyl esters

This presentation describes amino acid analysis with the gas chromatographic method and experimental conditions using the N-trifluoroacetyl n-butyl ester derivatives; the study we describe here was undertaken to compare gas chromatographic (GC) and ion-exchange chromatographic (IEC) analyses of amino acids in hydrolysates of 9 diverse sample types to gain insight into effects of these 2 chromatographic methods of analysis on variation in amino acid results. Our study showed that values for samples prepared by 2 separate laboratories using the same procedure were generally in good agreement when all of the hydrolysates were analyzed by a single laboratory using a single method of analysis. To compare results from gas chromatography with those from ion-exchange chromatography analyses were performed by 2 different laboratories on the same hydrolysates and on different hydrolysates prepared by the same method by both laboratories. The data demonstrate that GC and IEC can be expected to yield essentially identical results when applied to the same hydrolysate. Agreement is so close that interlaboratory differences in hydrolysate preparation of the same sample contribute as much to variation in amino acid results as does the method of analysis, a fact which should be noted in planning collaborative studies.     

Identification of amino acids in humic acid

Davidson, Sowden and Atkinson^l) in 1951 reported on the amino acids in the three soil organic matter fractions, and Stevenson, Marks, Varner and Martin~) in 1952 reported on the identification of eight amino acids from clay-adsorbed organic colloids in Brookstom slity clay loam. Also, some investigations on these amino acids have been carried out in our laboratory.