Effect of the structure of alcohols on their binding by thermotropic gels of corn starch

Binding of alcohols by thermotropic gels of normal corn starch was studied using the method of capillary gas-liquid chromatography. The amount of the gel-bound substances depended linearly on their concentrations in the original gel. Binding of n-alcanols increased with the length of the alkyl chain, exhibiting a linear dependence. The binding was attenuated by the presence of double bonds-cyclic substituents in or branching of the carbon chain. Binding of alcohols by starch polysaccharides was more pronounced in thermotropic gels, as compared to cryotextured gels. Binding isotherms were indicatice of co-operative interactions, in which alcohols formed supromolecular structures with hydrated molecules of polysaccharides and inclusion complexes with amylose and side chains of amylopectin.     

Binding of lactones by polysaccharides of corn and potato starches

Sorption of gamma- and delta-lactones from aqueous solutions by cryotropic gels of corn and potato starches was studied using capillary gas-liquid chromatography and Fourier transform infrared spectroscopy. The sorption patterns were similar for both types of starch. However, the sorption of lactones by potato starch was 5-10% lower than their sorption by cornstarch. The amount of substances bound by cryotextures of the starches depended linearly on their initial concentrations in gel. Increase in the length of the alkyl substituent improved sorption of lactones. It was shown that six-membered rings play a greater role in total lactone sorption than five-membered rings. The apparent constants and numbers of binding sites were estimated for compounds that reached the stage of saturation. The interaction between lactones and polysaccharides was accompanied by a decrease in their conformational lability and changes in the rheological characteristics of thermotropic and cryotropic starch gels.     

Binding of Lactones by Polysaccharides of Corn and Potato Starches

Sorption of - and -lactones from aqueous solutions by cryotropic gels of corn and potato starches was studied using capillary gas–liquid chromatography and Fourier transform infrared spectroscopy. The sorption patterns were similar for both types of starch. However, the sorption of lactones by potato starch was 5–10% lower than their sorption by corn starch. The amount of substances bound by cryotextures of the starches depended linearly on their initial concentrations in the gel. An increase in the length of the alkyl substituent improved sorption of lactones. It was shown that six-membered rings play a greater role in total lactone sorption than five-membered rings. The apparent constants and numbers of binding sites were estimated for compounds that reached the stage of saturation. The interaction between lactones and polysaccharides was accompanied by a decrease in their conformational mobility and changes in the rheological characteristics of thermotropic and cryotropic starch gels.     

Dependence of alcohol binding from aqueous dispersions on physicochemical properties of starch

Binding of alcohols from aqueous dispersions of native cornstarches differing in amylose content was studied by means of capillary gas chromatography. The efficiency of this process was compared with that of binding to gelatinized starches. Studies of native and gelatinized starches showed that the amount of bound substances depended linearly on their initial concentration. Binding of alcohols did not differ in native and gelatinized normal starch and high amylose starch. The efficiency of binding increased with the length of the alkyl substituent. It should be emphasized that the highest efficiency of binding was observed with native starch. Native amylopectin starch was less potent than gelatinized starch in binding hexanol. The degree of alcohol binding was much lower in cryotextures of gelatinized starch.     

Dependence of alcohol binding from aqueous dispersions on physicochemical properties of starch

Binding of alcohols from aqueous dispersions of native cornstarches differing in amylose content was studied by means of capillary gas chromatography. The efficiency of this process was compared with that of binding to gelatinized starches. Study of native and gelatinized starches showed that the amount of bound substances depends linearly on their initial concentration. Binding of alcohols did not differ in native and gelatinized normal starch and high amylose starch. The efficiency of binding increased with an increase in the length of the alkyl substituent. It should be emphasized that the efficiency of binding was highest in native starch. Native amylopectin starch was less potent than gelatinized starch in binding hexanol. The degree of alcohol binding was much lower in cryotextures of gelatinized starch.     

Effect of the composition of polysaccharides in gelatinized cornstarch on alcohol absorption

Sorption of alcohols in aqueous suspensions of gelatinized cornstarches with various contents of amylose was studied by capillary gas chromatography. Alcohol sorption depended primarily on the structure of alcohols, but not on the composition of polysaccharides. No correlation was found between the efficiency of sorption and amylose content in starch. The amount of substances sorbed by starches depended linearly on their initial concentration in the gel. Normal and highly amylose starches sorbed alcohols to a similar degree. However, increasing the length of alkyl substituents improved sorption of alcohols. Amylopectin starch differed in high affinity for small molecules and low sensitivity to the structure and hydrophobicity of alcohols.     

Effect of the Composition of Polysaccharides in Gelatinized Cornstarch on Alcohol Absorption

Sorption of alcohols in aqueous suspensions of gelatinized cornstarches with various contents of amylose was studied by capillary gas chromatography. Alcohol sorption depended primarily on the structure of alcohols, rather than on the composition of polysaccharides. No correlation was found between the efficiency of sorption and amylose content in starch. The amount of substances sorbed by starches depended linearly on their initial concentration in the gel. Normal and high-amylose starches sorbed alcohols to a similar degree. However, increasing the length of alkyl substituents improved sorption of alcohols. Amylopectin starch differed in high affinity for small molecules and low sensitivity to the structure and hydrophobicity of alcohols.     

Effect of water-soluble and insoluble non-starch polysaccharides isolated from wheat flour on the rheological properties of wheat starch gel

Water-soluble (WSP) and insoluble non-starch polysaccharides (WIP) were isolated from wheat flour to evaluate the effects of WSP and WIP on starch gel properties. Isolated WSP and WIP were added to two types of isolated wheat starch with different amylose content at a concentration of 3% based on the dry weight of starch. 30% starch gels were prepared and stored at 5 °C for 1, 8, or 24 h. The dynamic viscoelasticity of 30% starch gels mixed with WSP and WIP was measured using parallel plate geometry, showing that WSP and WIP affected the elastic component of starch gels in opposite ways. Adding WIP increased the storage shear modulus (G′) of starch gels, while adding WSP decreased G′ and dramatically increased the loss tangent (tan δ=G″/G′).     

Mechanisms involved in the biosynthesis of polysaccharides

The mechanisms for the biosynthesis of three polysaccharides are presented: (i) starch synthesized by starch synthase and adenosine diphospho glucose; (ii) dextran synthesized by Leuconostoc mesenteroides B-512FMC dextransucrase and sucrose; and (iii) Acetobacter xylinum cellulose synthesized by cellulose synthase, uridine diphospho glucose, and bactoprenol phosphate. All three enzymes were pulsed with substrates, containing ¹⁴C-glucose and chased with the same nonlabeled substrates. When the polysaccharides were isolated, reduced, and hydrolyzed, the pulsed reactions gave ¹⁴C-glucitol, which was significantly decreased in the chase reaction. These experiments definitively show that all three polysaccharides are biosynthesized by the addition of glucose to the reducing-ends of the growing polysaccharides and not by the addition to the nonreducing-ends of primers. Additional evidence indicates that glucose and the polysaccharides are covalently attached to the active-sites of the enzymes. A two catalytic-site insertion mechanism at one active-site is proposed for the biosyntheses. Two of the polysaccharides are α-linked glucans, starch and dextran, and cellulose is a β-linked glucan, known for several years to require a bactoprenol lipid phosphate intermediate. It is shown how this intermediate is involved in determining that β-linkages are synthesized. Other β-linked polysaccharides: bacterial cell wall peptidomurein, Salmonella O-antigen polysaccharide, and Xanthanomonas camprestris xanthan, are heteropolysaccharides, with the later two also being hetero-linked polysaccharides, with the β-linkage at the reducing-end of the repeating unit. All three require bactoprenol lipid phosphate intermediates and are biosynthesized by the addition of the repeating units to the reducing-end of a growing polysaccharide chain, with the formation of a β-linkage.     

Binding by Cornstarch of Components of a Mixture of Volatile Organic Substances from Aqueous Solutions

Effects of the composition of a mixture of organic substances on the binding of individual components in aqueous dispersions of native and gelatinized cornstarches with different contents of amylose was studied by capillary gas chromatography. Binding was more active when alcohols were exposed to cornstarch as mixtures rather than individual compounds. In a multiple-component mixture, compounds belonging to distinct classes competed with each other for binding sites. Odorant binding by aqueous starch dispersions was more sensitive to the composition of the mixture and the nature of starch when studied in aqueous dispersions of native starches (compared to those of gelatinized starches).     

Thermotropic Properties of Cellular Membranes in Dormant and Non-Dormant Echinochloa crus-galli(L.) Beauv. Seeds

Steady-state fluorescence polarization measurements with l,6-diphenyl-l,3,5-hexatriene(DPH) were used to monitor thermotropic transitions in microsomalfractions and plasma membrane vesicles isolated from barnyardgrass[Echinochloa crus-galli (L.) Beauv.] seeds during the transititionfrom dormancy to germination. The effect of dormancy-relievingor inactive alcohols on the thermotropic properties of the cellularmembranes was determined both in vivo and in vitro. Membranefractions isolated from dormant seeds showed some discontinuitiesin the Arrhenius plots. In non-dormant or germinating seedscellular membranes showed linear Arrhenius plots over the entirerange of temperature examined. Membrane preparations from imbibedseeds showed a similar pattern in their Arrhenius plots upontreatment with the various alcohols in vitro. The results suggestthat the release from dormancy in seeds is associated with somechanges in their cellular membranes. Key words: Germination, alcohols, thermotropic transition     

Effect of ‘Mixtalol’ on growth,yield and yield components of Indian mustard (Brassica juncea)

Mixtalol (a mixture of long chain aliphatic alcohols varying in chain length from C₂₄ to C₃₂) applied to Brassica juncea plants as foliar spray caused an increase in secondary and tertiary branching with consequent enhancement in seed yield through increased number of inflorescences and siliquae per plant. The percentage of immature siliquae and shattering of siliquae decreased with this treatment. Mixtalol increased total dry matter of plants, partitioning coefficient and harvest index. The contents of starch, protein and oil were also higher in seeds from Mixtalol treated plants.     

ENZYME PATTERNS DURING A SYNCHRONOUS GROWTH CYCLE OF CHLORELLA PYRENOIDOSA

There have been no studies in which a significant number of isozymes have been investigated during a synchronous growth cycle of any organism. The present study was designed to obtain information on the fluctuations of a broad spectrum of enzymes during a synchronous growth cycle of Chlorella pyrenoidosa. Of the thirty-two enzymic activities investigated, seventeen could be localized on starch gels from a high temperature strain of Chlorella pyrenoidosa. Nine of these activities were found to possess more than one band of activity by starch gel electrophoresis. Seven of these activities were localized on starch gels throughout a synchronous growth cycle of C. pyrenoidosa grown in continuous light. Assay techniques are described. The fluctuations in enzyme activity are discussed with relation to concurrent metabolic and cytological changes during cell maturation in C. pyrenoidosa.     

Non-covalent interaction between procyanidins and apple cell wall material. Part III: Study on model polysaccharides

The adsorption of condensed tannins (procyanidins) of varying degrees of polymerisation and percentage of galloylation on solid polysaccharides substrates was quantified using the Langmuir isotherms formulation. Pectins and xyloglucans, which are soluble polysaccharides, were first cross-linked by, respectively, dibromopropane and epichlorohydrin to obtain insoluble covalent gels. Cellulose and starch, being insoluble in the buffer solution at room temperature, were used as bought. Apparent affinity constants obtained for the pure polysaccharides were as follows: pectin>xyloglucan>starch>cellulose. The apparent affinity constants increased with the molecular weight of the procyanidins, except with cellulose. Higher affinities were obtained with pectin, a polysaccharide having the ability to develop a gel-like network, forming hydrophobic pockets able to encapsulate procyanidins. Filamentous and globular polysaccharides, like cellulose and xyloglucan, bound procyanidins weakly. Higher apparent saturation levels were obtained for cellulose and xyloglucans, the arrangement of which would favour cooperativity and stacking. Pectin had lower saturation levels probably due to a steric hindrance effect.     

Trehalase activity in extracts of Phycomyces blakesleeanus spores following the induction of germination by heat activation

The heat activation of trehalase in extracts of sporangiospores of Phycomyces blakesleeanus, following the induction of germination by heat activation and the gelatinization of potato starch granules were studied under different conditions in order to discriminate between several phenomena as possible triggers in the activation of trehalase.Short-chain alcohols (from methanol to pentanol) lower the activation temperature of trehalase while long-chain alcohols (from heptanol to nonanol) raise it. Short-chain alcohols also lower the gelatinization temperature of potato starch granules, while long-chain alcohols, hexanol and heptanol have hardly any influence on the gelatinization temperature. Octanol raises the gelatinization temperature. More polar phenols lower the activation temperature of trehalase, while more apolar phenols will raise it. The gelatinization temperature of starch granules is more lowered by the polar polyphenols than by the more apolar phenols.The effect of high pressure on starch gelatinization was investigated in order to compare data from such a model system with the data on trehalase activation.The gelatinization temperature of starch granules is shifted upwards with about 3–5 K/1000 atm (1.013×10⁵ kPa). Pressures higher than 1500 atm do not further increase the gelatinization temperature. However, no reversal of the effect, as occurs with protein conformational changes, is seen with pressure up to 2500 atm. Also for trehalase activation we find a continuous upward shift of the activation temperature with about 5–9 K/1000 atm. These data are in agreement with a thermal transition in a polysaccharide matrix, being the trigger in the heat activation of trehalase.     

Utilization of starch and synthesis of a combined amylase/αα-glucosidase by the human colonic anaerobe Bacteroides ovatus

Bacteroides ovatus preferentially utilized starch and pectin when grown on a mixture of polysaccharides in batch culture, indicating that these carbohydrates are important substrates for the bacterium in the human large intestine. Further studies on starch breakdown showed that continuous cultures grew on the polysaccharide when it provided the sole carbohydrate source, to yield a single hydrolytic product at low dilution rates ( D = 0·04 h⁻¹), with an estimated molecular mass of 13 kDa. In contrast, two major types of oligomeric products were formed at higher dilution rates ( D = 0·44 h⁻¹), with approximate molecular weights of 11 and 140 kDa. Analysis of cell-associated starch-degrading enzymes produced by Bact. ovatus using ion exchange chromatography and HPLC gel-filtration showed that amylase and α-glucosidase activities eluted in the same fractions. The single peak containing amylase and α-glucosidase activities obtained by HPLC gel-filtration chromatography corresponded to a molecular mass of approximately 140 kDa, and activity staining of gels for α-glucosidase activity after polyacrylamide gel electrophoresis, in the presence of sodium dodecyl sulphate, gave an estimated molecular mass of 70 kDa, indicating this enzyme to be a dimer. After renaturation, the 70 kDa band was cut from the gels and solubilized. The extract hydrolysed gelatinized starch and p -nitrophenyl-α- D -glucopyranoside.     

Impact of incorporations of various polysaccharides on rheological and microstructural characteristics of heat-induced quinoa protein isolate gels

This study aimed to investigate the properties of heat-induced gels (85 °C for 30 min) of quinoa protein isolate (QPI) in the presence and absence of various polysaccharides including guar gum (GG), locust bean gum (LBG), and xanthan gum (XG) at pH 7. For this purpose, samples with three gum concentrations (0.05, 0.1, and 0.2 wt%) at a fixed QPI concentration (10 wt%) and a fixed ionic strength (50 mM NaCl) were studied in terms of their gelation behaviour, small and large deformation rheological properties, water holding capabilities, and microstructural characteristics. Rheological measurements revealed that all polysaccharides incorporation could improve gel strength (complex modulus, G*) and breaking stress, accelerate gel formations, and more stiffer gels were obtained at greater polysaccharide concentrations. The XG exhibited the most gel strengthening effect followed by LBG and GG. Incorporation of 0.2 wt% XG led to a 15 folds increase in G* compared to the control. Confocal laser scanning microscopy observation revealed that the polysaccharides also altered gel microstructures, with the gels containing XG showing the most compact gel structures. The findings of this study may provide useful information for the fabrication of novel QPI based food gel products with improved texture.

     

Optimization of the Cellulase−Ultrasonic Synergistic Extraction Conditions of Polysaccharides from Lenzites betulina

Lenzites betulina has been recognized as a rich source of chemical components, including polysaccharides, sterides and sugar alcohols. In this study, cellulase?ultrasonic synergistic extraction method was applied to extract polysaccharides from L. betulina, and the response surface methodology was used to optimize the extraction conditions. The eight basic factors affecting extraction yield were evaluated by Plackett?Burman design (PBD). Then, the four important factors significantly affecting the yield of polysaccharides from L. betulina, including enzymolysis temperature, enzymolysis time, ultrasound time and ultrasound temperature, were optimized by Box?Behnken design (BBD). Maximum extraction yield of L. betulina polysaccharides was 13.64±0.09 % at a cellulase dosage of 0.8 %, enzymolysis temperature of 60 °C, enzymolysis time of 180 min, pH of 4.5, liquid‐solid ratio of 45 ml/g, ultrasound power of 300 W, ultrasound time of 20 min and ultrasound temperature of 45 °C. Subsequently, the characteristic structure of crude polysaccharides was determined by FT‐IR. Results indicated that cellulase?ultrasonic synergistic treatment is suitable for L. betulina polysaccharides extraction, and it has good prospect for development and utilization.     

Continuous production of l-serine by immobilized growing Corynebacterium glycinophilum cells

Summary Auxotrophic mutant cells of Corynebacterium glycinophilum with high l-serine production activity were immobilized by entrapment with various gel materials, such as synthetic prepolymers and natural polysaccharides. The entrapped cells were used for estimation of l-serine productivity in a medium supplemented with glycine as a precursor. Based on the above criteria, including cell growth in gels and cell leakage from gels, calcium alginate was the most suitable gel material. Continuous l-serine fermentation with calcium alginate-entrapped growing cells was successfully achieved in an air-bubbled reactor for at least 13 days.     

Adulteration identification of some fungal polysaccharides with SEM, XRD, IR and optical rotation: A primary approach

Edible mushrooms have been consumed in Asian countries for healthy functions historically with polysaccharides, which have been manufactured as ending products, as one of the major bioactive components. Driven by profits, some inglorious manufacturers conducted adulteration using cheap carbohydrates. The extracted polysaccharides from Agaricus blazei Murill, Ganoderma lucidum and Lentinus edodes were chosen as products and maltodextrin, carboxymethyl cellulose (CMC), water soluble corn starch and guar gum as adulterants for adulteration investigation. Scanning electron microscope (SEM) observation implied regular granular shapes of fungal polysaccharides different significantly from the adulterants. Infrared spectra revealed α- and β-anomeric types of polysaccharides and carbohydrates. X-ray diffractometry (XRD) suggested different diffraction patterns of polysaccharides from adulterant carbohydrates, the former were amorphous while the later somewhat crystalline of different crystallinity. Chiral properties of polysaccharides and carbohydrates showed big differences in specific rotation with good correlation between the content of “pure” fungal polysaccharides and adulterants.