The amino acid composition of the proteinaceous component of gum tragacanth (Asiatic Astragalus spp.)

Six Iranian and seven Turkish samples of commercial gum tragacanth, and a sample of Turkish 'gum traganton', have been studied. Their nitrogen content varied from 0.17 to 0.58%. Their amino acid compositions are characterized by the presence of very large but variable proportions of hydroxyproline and substantial proportions of serine, proline and valine. The data presented may be useful for extending the current specifications for identity and purity, at present based solely on polysaccharide parameters, for gum tragacanth (E413).     

Determination of galactomannan (gum) in guar (Cyamopsis tetragonolobus) by high performance liquid chromatography

A method is described for analysis by HPLC of galactomannan (gum) in seed of guar (Cyamopsis tetragonolobus (L) Taub). The dry seed is ground in 950 ml litre^?1 ethanol, and free sugars are removed by ethanol extract; the seed residue is hydrolysed with 2 M trifluoracetic acid in a pressure cooker (1 h at ? 105 kPa). Hydrolysing the gum in situ avoids the problems common with other techniques of extracting different fractions of gum, each having different mannose: galactose ratios. The method serves as a simple measure of gum contents in guar, and up to 20 samples per day can be processed.     

Expression of the alpha-galactosidase from Cyamopsis tetragonoloba (guar) by Hansenula polymorpha.

The methylotrophic yeast Hansenula polymorpha, a host organism for the production of heterologous proteins, has been applied to produce the alpha-galactosidase from the plant Cyamopsis tetragonoloba (guar). The yeast/Escherichia coli shuttle expression vector used is based on the origin of replication of the endogenous 2 microns plasmid of Saccharomyces cerevisiae and the LEU2 gene of S. cerevisiae for selection in H. polymorpha. In the expression vector, the alpha-galactosidase is controlled by the methanol-regulated promoter from the methanol oxidase gene, MOX, of H. polymorpha. The signal sequence of SUC2 (invertase) from the yeast S. cerevisiae, was used to ensure secretion of the alpha-galactosidase enzyme. After transformation and stabilization, the expression vector was stably integrated in the genome. The active alpha-galactosidase enzyme was efficiently secreted (greater than 85%) and after methanol induction, the expression level was 42 mg/l. Amino-terminal sequencing of the purified alpha-galactosidase enzyme synthesized by H. polymorpha showed that the S. cerevisiae invertase signal sequence was correctly processed by H. polymorpha. The secreted alpha-galactosidase was glycosylated and had a sugar content of 9.5%. The specific activity of the alpha-galactosidase produced by H. polymorpha was 38 U mg-1 compared to 100 U mg-1 for the guar alpha-galactosidase. Deglycosylation of the H. polymorpha alpha-galactosidase restored the specific activity completely.     

Variation in protein and trypsin inhibitor activity with maturity and amino acid composition of winged bean (Psophocarpus tetragonolobus) seeds

The protein and trypsin inhibitor activity in pods and seeds of winged bean (Psophocarpus tetragonolobus (L) DC) increase, and in the pod hull decrease, with the maturity of plant. The seeds of 21 cultivars both exotic and of Indian origin cultivated on marginal alkaline soil (pH 8.7) were analysed for protein (36.4–45.3) and amino acid composition (lysine 4.8 to 6.7).     

刺槐豆胶/瓜尔豆胶复合体系的流变学性质研究

研究刺槐豆胶(LBG)/瓜尔豆胶(GG)复合体系的流变学性质,并采用流变学的模型进行拟合分析。实验表明:BG/GG复合体系为非牛顿流体,流动曲线服从Carreau模型,随着LBG比例的增大,其粘度越小,非牛顿性越不明显,触变性越低。LBG与GG复配对粘度的影响可产生协同作用,LBG/GG=1∶9时,复合体系粘度最大。在频率扫描范围内,LBG/GG复合体系同时具有粘性和弹性,随不同的角频率处理展现不同的动态粘弹性行为,LBG/GG=1∶9时,复合体系的动弹粘弹性最大。      

Proteins and trypsin inhibitor activity of guar (Cyamopsis tetragonoloba L. Taub) seed

Proteins soluble in tris-acetate buffer (pH9.0) were fractionated by DEAE-cellulose, DEAE-Sephadex A-50 and Sephadex G-200 column chromatography. The purified proteins which contained 5–6% carbohydrate, had molecular weights of 125 900 and 22 390 amu. The high molecular weight fraction was homogeneous by polyacrylamide gel electrophoresis. Proteins extracted in phosphate buffer (0.1M , pH7.6) when subjected to Sephadex G-200 gel chromatography were resolved into three fractions, all of which showed considerable trypsin inhibitor activity. Germination for 3 days reduced the trypsin inhibitor activity of the seed by about 30%.     

Moisture adsorption isotherms of guar (Cyamposis tetragonoloba) grain and guar gum splits

Moisture adsorption isotherms of guar grain and guar gum splits were determined at 10, 20, 30 and 40 °C and 23-96% relative humidities using gravimetric method. The sorption data were fitted to six well-known sorption isotherm models (modified Chung-Pfost, modified Halsey, modified Henderson, modified Oswin, Chen-Clayton, and GAB models) using non-linear least square method. The GAB model was found the most satisfactory for representation of the equilibrium moisture content data for guar grain and guar gum splits. The equilibrium moisture content of guar gum splits was found to be significantly higher (p < 0.05) than that of guar grain. The isosteric heat of sorption was determined from the equilibrium moisture adsorption data using Clausius-Clapeyron type equation. Exponential relationship described well the dependence of isosteric heat of sorption on the equilibrium moisture content. The enthalpy-entropy compensation theory applied to sorption isotherms indicated enthalpy controlled sorption process.     

The amino acid composition and quantitative sugar-amino acid relationships in sequential Smith-degradation products from gum talha (Acacia seyal Del.)

Data are presented for the amino acid and sugar compositions of gum talha (tahl), i.e. the exudate from Acacia seyal Del., and for four sequential Smith-degradation (SD) products (0.10, 0.19, 0.38, 1.60 and 2.22% N respectively). Gum talha, which is not permitted as a food additive, is liable to occur as a contaminant of shipments of legitimate gum arabic (Acacia senegal (L.) Willd.). The molar polysaccharide/protein ratio in the whole gum (113:1) decreased to 58:1, 27:1, 5.5:1 and 4:1 in the first, second, third and fourth SD products respectively. From previous studies, SD-IV is known to be a branched galactan; hydroxyproline, aspartic acid, serine, valine, proline, and leucine account jointly for 70% of its amino acids. The first SD eliminated large amounts of sugars (ca 50%, including all of the rhamnose and glucuronic acid present) but only very small amounts of amino acids (molar ratio 807/1). The second and third degradations eliminated all of the arabinose and 99% of the galactose originally present. The very small yield of the final SD product is an established characteristic of dextrorotatory Acacia exudates of the A. seyal type (Bentham's Gummiferae). Overall (four SD stages), 99.7% of the original sugars but only 91.3% of the amino acids were eliminated. Hydroxyproline accounts for ca 25% of the low amino acid content of A. seyal gum and each of its SD products; the proteinaceous enrichment of the branched galactan core also involves aspartic acid, glutamic acid and iso-leucine.(ABSTRACT TRUNCATED AT 250 WORDS)     

A study of polyphenols in the seeds and leaves of guar (Cyamopsis tetragonoloba L. Taub)

Gallotannins, gallic acid, gallic acid derivatives, myricetin-7-glucoside-3-glycoside, kaempferol-7-glucoside-3-glycoside, kaempferol-3-rutinoside, kaempferol-3-glucoside, chlorogenic acid, caffeic acid and ellagic acid were derived from guar seeds and identified by chromatographic and spectral analysis. Myricetin-7-glucoside-3-glycoside, kaempferol-7-glucoside-3-glycoside, kaempferol-3-rutinoside, kaempferol-3-glucoside, quercetin-3-rutinoside, 2,3,4-trihydroxybenzoic acid, texasin-7-O-glucoside, daidzein-7-O-glucoside, chlorogenic acid and p-coumaryl quinic acid were found in guar leaves. The polyphenolic content of guar seeds depended on the stage of maturity varying from 1.26 to 0.69% total phenols; 0.49 to 0.12% gallic acid; 0.5 to 0.21% gallotannins; and 0.13 to 0.23% flavonols (all as percentage dry matter). The polyphenolic content of guar leaves varied from 0.74 to 1.24% total phenols; 0.18 to 0.84% flavonols; and 0.05 to 0.24% hydroxycinnamic acids in the dry matter of guar leaves.     

The effect of Bradyrhizobium inoculation on yield and seed quality of guar (Cyamopsis tetragonoloba L.)

Bradyrhizobium strains TAL 169 and TAL 1371 (introduced) and strains ENRRI 16A and ENRRI 16C (local) were used to inoculate five guar cultivars, namely, HFG-75, HFG-182, HFG-363, HFG-408 and WB-195 in a factorial field experiment. The objective of the experiment was to study the effect of inoculation on yield, proximate analysis and mineral composition. Most of the Bradyrhizobium strains significantly increased yield, protein, crude fibre, and mineral content. The locally-isolated strains affected these parameters more than the introduced ones. This study revealed that inoculation with Bradyrhizobium strains improved yield and seed quality of guar.     

The lipid and amino acid composition of the kiwi (Apteryx australis mantelli) ratite eggs

A complete lipid assay of the egg contents from the New Zealand kiwi (Apteryx australis mantelli) was carried out and compared with that of the domestic hen. The proportion of lipid to protein in the kiwi egg (1:0.5) is nearly twice as great as in the eggs of the domestic hen (1:0.9). Hen's egg lipids also have lower quantities of triacylglycerols (65 %) and higher phospholipids (29 %) as compared with those of kiwi egg lipids as 83 % and 8 % respectively. The overall fatty acid composition from the individual major lipid constituents and protein amino acid composition of the kiwi egg matched those of the domestic hen.     

The effect of shear rate on the viscosity of solutions of guar gum and locust bean gum

The apparent viscosities of aqueous solutions of guar gum and locust bean gum have been measured over a range of shear rates from 14 to 1142 s^?1. Comparable measurements were also made on gum solutions to which glucose, sucrose or glucose syrup had been added. For all the solutions the variation of relative viscosity with shear rate fits a power law equation. Addition of sugar has no effect on the non-Newtonian behaviour of the gum solutions. The relative viscosity of the gum in the sugar solutions is lower than in water. The ratios of the relative viscosities closely correspond with the ratios of the intrinsic viscosities. This is interpreted in terms of a smaller extension of the gum molecule in the sugar solution.     

阳离子型瓜耳胶在卷烟纸生产中的应用

介绍了阳离子型瓜耳胶的主要性能指标、使用要求与生产试验。     

The effect of guar gum on microbial activity in the human colon

On feeding a human volunteer a control diet for 21 days, followed by one containing 13·9 g guar/day for a further 21 days, the major changes seen were an increase in faecal output and water content and a decrease in faecal pH and transit time. Faecal output remained high for at least 10 days after return to the control diet. Short chain fatty acid (SCFA) levels/g wet weight of faeces were unchanged during the guar diet but total excretion of SCFA increased because of increased faecal output. Bacterial output was increased although the proportion of guar fermenters remained approximately 20%. Utilization of guar was complete from the beginning of the guar diet, with no period of adaptation. Flatus production substantially increased during the first 10 days of the guar diet but was less noticeable thereafter, suggesting that changes in the pattern of metabolism were taking place in response to continued feeding of guar. Addition of guar to the diet increased α-galactosidase, mannanase and β-mannosidase activity in faeces and most of the activity was associated with the bacterial fraction. In vitro incubation of faecal slurries from the control and guar diets with guar, galactose or mannose showed that SCFA production was lowest and gas production highest when guar was substrate. No effect of diet was seen on utilization of carbohydrate, SCFA and gas production or enzyme activity. Enzyme activity was only induced by guar and was mainly cell-associated.     

The physiological and rheological effects of foods supplemented with guar gum

The high molecular weight polysaccharide Guar gum has a plethora of uses in the food, pharmaceutical and paint industries. This polysaccharide is also employed as a dietary fibre, but the quantity used in food is limited due to its viscous properties. Guar gum may be modified enzymatically or chemically to reduce its molecular weight and by extension its viscosity. This modification though is believed to reduce its physiological efficacy, for example the attenuation of postprandial glycemia. However, a number of studies have shown the viscosity effects alone of this fibre in vitro and in vivo is not always correlated with blunted glycemia. The absolute mechanisms behind the benefits seen with guar gum consumption are not known and studies have shown factors such as food composition, food matrix and food and fibre processing conditions may all play a significant role.     

Molecular weight of guar gum affects short-chain fatty acid profile in model intestinal fermentation

Dietary fiber exerts many beneficial physiological effects; however, not all types of dietary fiber display the same effects. Partially hydrolyzed guar gum (PHGG), a lower molecular weight form of guar gum, is more easily incorporated into food, but may have less pronounced physiological effects than the native form. The aim of this study was to identify differences in intestinal fermentability based on the molecular weight of guar gum. Guar gum of four molecular masses (15, 20, 400, and 1,100 kDa) was fermented using a batch in vitro fermentation system. Human fecal inoculum was the source of microbes. The 400-kDa fraction produced the greatest concentrations of total short-chain fatty acid (SCFA) at 8 h and the highest amounts of butyrate at 24 h. At 24 h, the 400-kDa fraction produced more total SCFA and propionate than the 15 kDa, but was not different than 20 kDa or 1,100 kDa fractions. The molecular weight of guar gum was positively correlated with acetate production and negatively correlated with propionate production. This study concludes that 400-kDa guar gum may be optimal for intestinal fermentability. In conclusion, the molecular weight of guar gum affects in vitro fermentability and should be considered when adding to a food or beverage.     

瓜尔胶在经纱上浆中的应用研究

在浆料中减少PVA用量后,加入瓜尔胶对纱线进行上浆,测试上浆纱的各项性能。这种加入瓜尔胶的混合浆料的某些性能与现行混合浆料的浆纱性能相似,但瓜尔胶黏度较大,上浆纱耐磨性较差。