Different Degrees Of Hydrolysis Research Articles

Enzymatic hydrolysis of soy protein isolate and effect of succinylation on the functional properties of resulting protein hydrolysates

Commercial defatted soy meal was solubilized in an aqueous solution at pH 8.5 to prepare a soy protein isolate (SPI) with 90.45% protein and 95% solubility. Soy protein hydrolysate (SPH) was obtained by enzymatic hydrolysis of the SPI using a neutral proteinase at different degrees of hydrolysis (DH=4, 6, 8 and 10). A previous heat treatment of native SPI at 80°C for 10 and 30 min caused a gradual dissociation and/or unfolding of some fractions of the soy protein leading to a decrease in high molecular weight fractions. Gel filtration chromatography of SPH with DH=8 indicated that the soluble fraction consisted mostly of low molecular weight peptides having a molecular weight less than 12.5 kDa. Combined hydrolysis and succinylation greatly increased protein solubility and caused marked changes in other functional properties depending on the degree of modification. ©

Influence of different degrees of hydrolysis of poly(vinyl alcohol) membrane on transport properties in pervaporation of IPA/water mixture

Crosslinked dense poly(vinyl alcohol) (PVA) membranes with different degrees of hydrolysis were prepared and used in sorption and pervaporation of isopropanol (IPA)/water mixtures. Partial flux of water permeation was increased with the water content in the liquid mixture, but the partial flux of IPA due to the coupling effect of sorption and permeation, had a maximum value. The degree of PVA hydrolysis and the feed temperature influenced the permeation flux and water selectivity due to crystallinity and the number of polar side groups in PVA. Thus the partial flux of water and IPA was inversely proportional to the degree of PVA hydrolysis and the selectivity of PVA for water was proportional to the hydrolysis level of PVA.

Poly(vinyl alcohol) and poly(vinyl pyrrolidone) blends: miscibility, microheterogeneity and free volume change

Blends of crystallizable poly(vinyl alcohol) (PVA) with poly(vinyl pyrrolidone) (PVP) were studied by differential scanning calorimetry (d.s.c.). PVA with different degrees of hydrolysis (88 and 99 wt%) and PVP with different molecular weights (10 000 and 360 000 g mol −1) were used. The blends exhibited a single glass transition, as determined by d.s.c., suggesting the miscibility of the system over the whole composition range studied. The enthalpy of fusion ( ΔH f), as well as the glass transition temperature ( T g), heat capacity ( ΔC p) and glass transition width ( Δw), were also determined by d.s.c. These parameters changed with the degree of hydrolysis of PVA, PVP molecular weight and blend composition. The behaviour of ΔC p vs blend composition was complex for the different pairs of blends, suggesting strong interaction between PVA and PVP. From the analysis of Δw dependence on blend composition we concluded that blends containing PVP of 10 000 g mol −1 exhibit a larger number of relaxations than blends containing high molecular weight PVP, indicating that the density of interactions is larger in the former.

Studies on determination of molecular weight for ultrahigh molecular weight partially hydrolyzed polyacrylamide

The molecular weight characterization of partially hydrolyzed polyacrylamide (HPAM) for enhanced oil recovery use is rather difficult because of its ultrahigh molecular weight copolymer and polyelectrolyte behaviors in solution. In this work the effects of aqueous NaCl solution concentration and degree of hydrolysis of polymer on molecular dimension were studied. A simple and precise method for determining molecular weight of HPAM is presented. The molecular weight of HPAM with any degree of hydrolysis can be calculated from the [η]−Mw equation of unhydrolyzed PAM in an H2O system by measuring , of HPAM obtained in aqueous NaCl solutions by extrapolating salt concentration to infinity. Because the values of of HPAM of different degrees of hydrolysis are all equal to the corresponding [η] value of the unhydrolyzed PAM of the same degree of polymerization, the molecular weight of HPAM of any degree of hydrolysis can thus be calculated from the [η] − Mw equation for PAM homopolymer. © 1996 John Wiley & Sons, Inc.

Kinetic of in vitro generation of some hemorphins: early release of LVV-hemorphin-7, precursor of VV-hemorphin-7

Bovine globin has been hydrolysed by pepsin to different degrees of hydrolysis. Analysis of the hydrolysates, by reversed-phase high-performance liquid chromatography (RP-HPLC), shows the release of LVV- and VV- hemorphin-7. LVV-hemorphin-7 was the first generated, at a degree of hydrolysis (DH), as low as 4%. In contrast, VV-hemorphin-7 was produced later. Our study clearly shows that VV-hemorphin-7 is issued directly from LVV-hemorphin-7, since this later completely disappeared during hydrolysis. This work allows us to suggest a possible pathway for in vivo hemorphins appearance.

Hydrogen Bonding and Sequence Distribution in Poly(vinyl acetate-co-vinyl alcohol) Copolymers

The correlation between hydrogen-bonding self-association and sequence distribution in different poly(vinyl acetate-co-vinyl alcohol) copolymers (ACA) of different degrees of hydrolysis and sequence distributions has been studied by infrared and NMR spectroscopy. For ACA copolymers, quasi-random distributions are obtained by acid alcoholysis, blocker distributions by saponification, and intermediate distributions by acombined method, as shown by 13 C NMR. FTIR spectroscopy has pointed out that hydrogen-bonding distribution in ACA copolymers strongly depends on sequence distribution. For block copolymers, hydroxyl-hydroxyl self-association is preferred

Correlation between microscopic structural parameters and macroscopic flow behaviour of some polymer‐surfactant systems suitable for tertiary oil recovery

AbstractSome materials, suitable for application in polymer‐surfactant flooding used in tertiary oil recovery (EOR), have been characterized by static and dynamic light scattering and studied in respect to their suitability in various model brines by measuring their rheological and dynamic‐rheological behaviour. Xanthan and polyacrylamides of different degree of hydrolysis have been used as polymers, an ethylene glycol sulfonate as surfactant.Correlations have been established between microscopic structural parameters (Hydrodynamic radius, radius of gyration, molar mass, shape of the polymers) and the macroscopic behaviour, such as viscosity and elasticity, being important rheological parameters for EOR application. Additional investigations on surface tension and long term viscosity study lead then to a judgement for the efficiency and long term stability of polymer‐surfactant slugs in various reservoirs of different salinity.

Growth of young rats on diets based on fish silage with different degrees of hydrolysis

The effect of storage for up to 1 year on the nutritional value of ensiled cooked and non-cooked minced capelin was determined in growth experiments with young rats. Minced fresh capelin of the same batch was also included. Cooked silage came out best after the storage of 1 year showing both better growth and protein efficiency ratio (PER). There were no significant differences in apparent digestibilities. Rats given the uncooked silage accumulated more glycogen in the liver than the rats given the cooked silage diet ( p < 0.01). The hepatosomatic index and the liver fat content were higher in the rats given cooked silage. No differences were found in hepatic ash and protein contents. The rats given raw minced capelin performed worse than the rats given the silages of up to 180 days of storage, but they performed better than those with 1 year of storage. This was probably due to the procedure used for mixing the diet.

Enzymic Protein Hydrolysates

ABSTRACTIt is demonstrated that by-products from food industry are main substrates for production of enzymic protein hydrolysates and their undesirable components or properties are summarized. The methods for obtaining of enzymic protein hydrolysates having different degree of hydrolysis are reviewed with a special regard to the control of the catalytic process. The use of immobilized enzymes and membrane technologies is discussed in respect to the final effectiveness. The debittering of enzymic protein hydrolysates and the analytical methods for their characterization are surveyed. Microbiology, food industry and pharmacy are presented as the main fields for application of these products. It is concluded that there are many reasons for development of enzymic protein hydrolysates production and use in Bulgaria.

A study of steric stability of coal—water dispersions by ultrasonic absorption and velocity measurements

The temperature dependence of the steric stability of concentrated coal-water dispersions was studied by ultrasonic absorption and velocity measurements. The dispersions were stabilized by a thin layer of the random block copolymer poly(vinyl alcohol)-poly(vinyl acetate) (PVA) with two different degrees of hydrolysis and in a manner known to result in adsorption of the PVA in a loop/train conformation. There is a destabilization process which leads to flocculation of the dispersion with a rise in temperature. This process appears to be reversible for dispersions stabilized with adsorbed PVA whereas uncoated dispersions show irreversible flocculation. Flocculation is market by a sudden rise of the ultrasound velocity, and this property was used to determine the temperature and reversibility of flocculation, which was found to occur at the Θ-temperature of the PVA solution (also detected by ultrasonic velocity measurements) or at higher temperature for a coal—water—PVA dispersion with “enhanced steric stability.” The stabilized coal—water dispersions showed nearly shear-rate-independent flow behavior, indicating an insignificant viscous interaction between the adsorbed PVA and the supernatant at low shear rates. The depth of penetration of shear waves at ultrasonic frequencies is comparable to the thickness of the adsorbed PVA layer. Ultrasonic absorption measurements indicated that there are energy dissipating mechanisms, which are interpreted to be due to the elastic and viscous response of the adsorbed PVA layer to the shear flow of the supernatant in the viscinity near the interface.

Esterification of phthalic anhydride by alcohols in the presence of titanium bis(β-diketonates)

In the esterification of phthalic anhydride by 2-ethylhexanol in the presence of titanium bis(β-diketonates), the rate constants of the reaction increase with decreasing stability of the chelate. The relation of the rate constant of the reaction of phthalic anhydride with normal C6-C9 alcohols catalyzed by bis (acetylacetonato) dibutoxytitanium and butyl orthotitanate in a medium of the corresponding diesters is extremal in nature because of the different degree of hydrolysis of the catalyst during esterification.

Influence of the degree of hydrolysis on the solubility of the protein hydrolysates from sardine (Sardina pilchardus)

AbstractThe influence of different degrees of hydrolysis on the solubility of sardine proteins and on its correlation with the molecular weight distribution of the protein hydrolysates was examined. All the hydrolysates showed high solubility with a more pronounced reduction for products with a lower degree of hydrolysis in acid pH at both high and low ionic strength. Furthermore, from the gel‐chromatographic analysis, a decrease was noted in the high molecular weight fraction as the degree of hydrolysis increased.

Graft copolymerization. II. Grafting of benzyloxyethyl methacrylate on poly(vinyl alcohol)

AbstractNew graft copolymers were produced by grafting benzyloxyethyl methacrylate, the benzyl ether of HEMA, on high‐molecular‐weight poly(vinyl alcohol) in dimethyl sulfoxide solution with Ce4+ as initiator. The effects of the concentration of the initiator, the concentration of the monomer, the total concentration of the reactants, the temperature, and the duration of reaction on the percentages of grafting and conversion were investigated. Further, also the relationships between the initiator concentration and the percentages of grafting and of conversion in the reaction with poly(vinyl alcohol)s of lower molecular weight and of different degrees of hydrolysis were studied.

Viscometric properties of dilute solutions of hydrolyzed polyacrylamide

The authors have measured the concentration dependence of the reduced viscosity η sp/c of hydrolyzed polyacrylamide with different degrees of hydrolysis h and neutralization α in dilute solutions of different ionic strength C s. It is shown that [η] of the polymer ( α=1) is a linear function of 1/√ C s. At C s = 1·91 mole/l. the value [η] does not depend on h so that the MW of hydrolyzed polyacrylamide with different h may be calculated from the same Mark-Kuhn formula. For samples with h ⩾0·2 and α⩽0·5 an anomalous dependence of function η sp/ c- c is found for all values of C s studied (0·005−1·910 mole/l.) which is explained by the self-ionization of the neutralized carboxyl groups of the polymer on dilution of the solution and the associated increase in the charge of the chain molecule and also by rupture of the possible intramolecular hydrogen bonds between the amide and carboxyl groups.

Flows of dilute hydrolyzed polyacrylamide solutions in porous media under various solvent conditions

AbstractExperimental results on pressure losses of flows of dilute polymer solutions through porous media are summarized. The polymer products employed in this study consisted of partially hydrolyzed polyacrylamides (HPAM) with different degrees of hydrolysis. The effect of the hydrolysis on the pressure drop is investigated in a porous media test section designed to minimize polymer degradation. The investigations were carried out for various solvent conditions, and it is shown that the maximum increase in pressure drop is mainly dependent on the molecular weight of the polymers. The onset of the polymer action is measured for various fluid and solvent properties. Particular attention is given to measurements near θ‐conditions. The results stress the importance of the solvent properties on the actions of the polymers and on the resultant pressure drop for porous media flows. The addition of salt ions to solutions of partially hydrolyzed polyacrylamides yields onset behavior previously observed for nonionic polymers. The differences measured between various solvent properties can be explained by the actual hydrodynamic molecule dimensions for a given molecular weight and polymer concentration. To quantify the influences of the solvent properties on the polymers, measurements were carried out in aqueous solutions for various pH values and therefore at various degrees of dissociation. The importance of separating polymer effects caused by their linear dimension in the solution from those that are introduced by and increase in solvent viscosity is shown. Measurements were performed to quantify the effects of solvent viscosity on the polymer action and to separate these effects from those due to changes in molecule dimensions. The implications of the present results are stressed in connection with applications of polymer solutions in tertiary oil recovery, and the positive features of the molecule actions on flow in such applications are described.

Vena contracta suppression in dilute polymer solutions

AbstractVery small amounts of high molecular weight polymers were found to eliminate vena contracta formation in flow through a circular orifice. This effect was reflected in the decreased efflux time for drainage between two fixed levels in a tank, reductions up to 30% being obtained. Aqueous solutions of seven commercially available polymers were studied, consisting of a poly(acrylic acid), two polyacrylamides of different degrees of hydrolysis, and four poly(ethylene oxides) of widely differing molecular weights. The poly(acrylic acid) and two highest molecular weight poly(ethylene oxides) each caused a sudden drop in efflux time at a “critical concentration”, which was 2, 50, and 90 wppm, respectively, for these three polymers. An explanation of this phenomenon in terms of the high Deborah number flow field existing near the orifice edge is advanced. In the case of the polyacrylamide solutions, a very gradual reduction in efflux time with increasing polymer concentration was observed, beginning at about 3 wppm. Coincident with this was the formation of a wine‐glass stem or converging flow field upstream of the orifice. Such a flow field was not observed for the other solutions. It is suggested that vena contracta inhibition with polyacrylamide is simply a manifestation of solution die swell. The reason for the differing efflux time behavior between the various polymers is not known and represents a challenging problem for further study.

27Al nuclear magnetic resonance studies of the hydrolysis and polymerisation of the hexa-aquo-aluminium(III) cation

The hydrolysis of aluminium salt solutions has been studied using 27AI and 1H n.m.r. and this has led to reliable values for the concentrations of the species of AI(H2O)63+, AI2(OH)2(H2O)84+, and AI13O4(OH)24(H2O)127+ at different degrees of hydrolysis. These ions do not account for all the aluminium in solution and another species, probably Al8(OH)20(H2O)x4+ is thought to be present. It is shown that previous controversy over the constitution of these solutions arose because of the different methods used for preparing the solutions: only the first two species exist when hydrated aluminium(III) chloride is dissolved in water whereas the highly polymeric species appear only after considerable hydrolysis has occurred at higher pH. The cations, particularly the dimer, may also be more hydrolysed than the above formulae indicate and this has probably confused the previous interpretation of the potentiometric results.

DEGRADATION OF VARIOUS MEAT FRACTIONS BY TENDERIZING ENZYMES

SUMMARYBeef round muscle was separated according to solubility characteristics into water soluble, salt soluble and insoluble fractions. These showed different degrees of hydrolysis when reacted with an enzyme. The magnitude varied with nature of the enzyme. Collagenase, bromelain and trypsin showed stronger solubilizing activity on the insoluble fraction than on the salt soluble fraction; whereas papain, Rhozyme P‐11 and ficin showed strong activity on the salt soluble fraction and hydrolyzed the insoluble fraction less efficiently. In general, the water soluble fraction was more resistant to enzyme hydrolysis than the other fractions, except with papain and Rhozyme P‐11. However, the portion of the water soluble fraction, that was hydrolyzed appeared as smaller peptides than the solubilized fregments of the other two fractions.

Gel Chromatographic Behavior of Aqueous Ferric Nitrate

Abstract Ferric nitrate solutions with different degrees of hydrolysis were investigated on polydextran gels having various exclusion limits. Typically chromatograms exhibited two well-resolved peaks, one at the void volume and the other at the total liquid volume of the gel. The respective peaks corresponded to higher and lower molecular weight fractions of the iron in the injected sample. Similar behavior was observed in “negative-peak” investigations where the positions of sample and eluent were reversed. Frontal analysis of the iron solution showed two breakthroughs corresponding to excluded iron moving in the void volume and admitted iron moving near the total liquid volume of the gel. The molecular size distribution of the ferric nitrate samples was studied as a function of OH-Fe ratio by noting changes in the percentage of iron in the respective fractions for gels having known exclusion limits.

Reaction kinetics and tacticity of macromolecules. I. Methacrylic acid—ester copolymers

AbstractThree different samples of polymethyl methacrylate of different tacticities were prepared, the first by the conventional method in the presence of benzoyl peroxide as initiator (conventional polymer), the second by a pseudo‐ionic method with phenylmagnesium bromide in toluene solution (polymer A), the third photochemically at −20°C. in toluene in the presence of benzoin (polymer B). On the basis of their infrared spectra, polymer A corresponds to a syndiotactic structure, while polymer B must be considered as a mixture of conventional and isotactic polymers. These polymethyl methacrylate samples were hydrolyzed in concentrated sulfuric acid up to different degrees of hydrolysis by heating up at 60°C., isolated, and purified. The kinetics of the hydrolysis of the corresponding acid—ester copolymers were studied; the reactions were carried out in buffered aqueous solution at different degrees of neutralization. Polymer A hydrolyzes about four to five times faster than the conventional polymethyl methacrylate, while polymer B hydrolyzes very slowly and must contain configurations which are resistant to acid hydrolysis in these experimental conditions; this configuration is probably the isotactic one.