Various Degrees Of Hydrolysis Research Articles

Improving the in vitro digestibility of rapeseed albumins resistant to gastrointestinal proteolysis while preserving the functional properties using enzymatic hydrolysis

Study of in vitro digestibility of high-quality isolate of rapeseed albumins (RA) was carried out in this work, using Size-Exclusion Chromatography. A poor in vitro digestibility of the RA isolate was highlighted (15%). The aim of this study was therefore to improve the RA in vitro digestibility by enzymatic hydrolysis while preserving its attractive functional properties. Alcalase, Flavourzyme and Prolyve were used to obtain 12 hydrolysates with various degrees of hydrolysis (DH) and compositions. All hydrolysates showed improved digestibility and those with the highest DH showed the best improvements. Techno-functional properties of these hydrolysates were also characterized. The poor emulsion capacity of initial RA was improved and results showed that extent proteolysis can be a good way to improve both digestibility and functional properties. Moreover, optimal conditions for RA proteolysis were identified to produce with Flavourzyme a partial hydrolysate (still containing 50% intact RA) that is both digestible and functional.

Gummi Formulations Comprising Amenamevir Solid Dispersions with Polyvinyl Alcohol.

The aim of the present study was to determine whether solid dispersions (SDs) are applicable to gummi formulations. Amenamevir was selected as a model of a poorly water-soluble drug, and polyvinyl alcohols (PVAs) with various degrees of hydrolysis (PVA 66, PVA 80, PVA 88, and PVA 66/88) were used as SD carriers. Design of experiments (DOE) was used to develop a gummi formulation that was suitable for an amenamevir SD using SD with PVA 66. Dissolution studies and clinical sensory tests on 11 formulations calculated by DOE revealed that a gummi formulation comprising 10.5% gelatin and 22.8% water was suitable for SD of the drug. Gummi formulations comprising amenamevir SDs with various PVAs were prepared using the determined gummi formulation, and their ability to dissolve amenamevir, their stability, and their oral absorption in dogs were evaluated. The results suggested that PVA 66, PVA 66/88, and PVA 80 were appropriate in terms of dissolution, stability, and in vivo absorption, respectively. Considering these results comprehensively, it was concluded that PVA 80, which enabled the highest degree of absorption, was the most suitable SD carrier for gummi formulations. Thus, it was possible to apply a PVA SD of amenamevir to gummi formulations.

Localized enzymolysis and sonochemically modified sunflower protein: Physical, functional and structure attributes.

Impacts of localized enzymolysis and sonication on physical, techno-functional, and structure attributes of sunflower meal protein (SMP) and its hydrolysate (SMPH) were studied. SMP was subjected to enzymolysis (using alcalase) to prepare SMPH with various degrees of hydrolysis (6-24% DH). Enzymolysis decreased colour lightness, turbidity, and particle size of unsonicated and sonicated SMP, while it increased the absolute values of zeta potential (P<0.05). Sonication improved oil absorption capacity and dispersibility over unsonicated samples. Contrarily, sonicated preparations showed a decrease in water holding capacity. Intrinsic fluorescence and FTIR spectral analyses suggested that SMPH had more movable/flexible secondary structures than SMP. Moreover, the changes in sulfhydryl clusters and disulfide linkages following sonication demonstrated limited unfolding of SMP and SMPH structure and decrease in intermolecular interactions. SDS-PAGE profile exhibited significant reduction in molecular weight (MW) of sonicated SMP, whereas did not display differences between unsonicated and sonicated SMPH. From further MW analysis, SMPH was categorized with high proportion of small-sized peptides≤3kDa fractions, which increased from 78.64 to 93.01% (control) and from 82.3 to 93.88% (sonication) with enzymolysis (6-24DH). Localized enzymolysis and sonication can be utilised to modify the physical and conformational attributes of SMP and SMPH, which could enhance their functionalities and broaden the utilisation area in food industry.

Improvement of the functional and antioxidant properties of rice protein by enzymatic hydrolysis for the microencapsulation of linseed oil

In this study, the potential use of rice protein hydrolysates as emulsifying and encapsulating agents in the microencapsulation of linseed oil by spray drying was evaluated. The proteases Alcalase and Flavourzyme were used to obtain protein hydrolysates with various degrees of hydrolysis from rice protein isolate. Linseed oil-in-water emulsions stabilized by maltodextrin and protein hydrolysates obtained by Alcalase or Flavourzyme were characterized by oil droplet size, ζ-potential, rheological behavior, emulsion stability, and emulsion capacity. The emulsions were spray dried and evaluated according to their encapsulation efficiency and lipid oxidation stability. The results showed that the emulsions stabilized by Flavourzyme protein hydrolysate presented smaller oil droplets and were more stable than Alcalase protein hydrolysate and rice protein isolate, resulting in high encapsulation efficiency (89.5%) for higher degree of hydrolysis. In contrast, microparticles containing Alcalase protein hydrolysate reduced the lipid oxidation of linseed oil during storage, due to higher antioxidant capacity of the protein hydrolysate.

Modification of the interfacial properties of sodium caseinate using a commercial peptidase preparation from Geobacillus stearothermophilus

Sodium caseinate was hydrolyzed with the commercial enzyme preparation Sternzym BP 25201, containing a thermolysin-like peptidase from Geobacillus stearothermophilus as the only peptidase. The hydrolysis was carried out at 65 °C with an enzyme activity of 1 nkat mL−1 or 15 nkat mL−1, leading to various degrees of hydrolysis (DH) ranging between 0.1 and 8.5%. The hydrolysates obtained were analyzed in a multi-scale approach, covering the hydrolysate properties (viscosity, hydrophobicity, peptide composition) and their interaction at oil–water (emulsion) and air–water (foam) interphases. The viscosity and surface hydrophobicity generally decreased with an increasing DH. Longer, more hydrophobic peptides, which self-assembled into network-like supramolecular particles, were detected up to a DH of 2.2%. Compared to untreated sodium caseinate, these structures could increase the half-life of emulsions (+400%) and foams (+31%). This was most probably caused by an increase in particle size (45.2-fold). By contrast, a higher DH led to a less hydrophobic product and smaller, spherical-shaped supramolecular structures. Foams and emulsions prepared with those hydrolysates were not stable and phase separated within minutes (for example, emulsion half-life = 5 min; foam half-life = 4.6 min at DH of 8.5%).

Extraction of unsaturated fatty acid-rich oil from common carp (Cyprinus carpio) roe and production of defatted roe hydrolysates with functional, antioxidant, and antibacterial properties.

Common carp roe is a rich protein and oil source, which is usually discarded with no specific use. The aims of this study were to extract oil from the discarded roe and examine functional, antioxidant, and antibacterial properties of defatted roe hydrolysates (CDRHs) at various degrees of hydrolysis (DH). Gas chromatography of fatty acid methyl esters revealed that common carp roe oil contained high levels of unsaturated fatty acids. The results of high-performance liquid chromatography-mass spectrometry indicated that enzymatic hydrolysis of defatted roe yielded higher content of essential amino acids. CDRHs displayed higher solubility than untreated defatted roe, which increased with DH. Better emulsifying and foaming properties were observed at lower DH and non-isoelectric points. Furthermore, water and oil binding capacity decreased with DH. CDRHs exhibited antioxidant activity both in vitro and in 5% roe oil-in-water emulsions and inhibited the growth of certain bacterial strains. Common carp roe could be a promising source of unsaturated fatty acids and functional bioactive agents. Unsaturated fatty acid-rich oil extracted from common carp roe can be delivered into food systems by roe oil-in-water emulsions fortified by functional, antioxidant, and antibacterial hydrolysates from the defatted roe. © 2017 Society of Chemical Industry.

Angiotensin-I converting enzyme inhibitory and antioxidant activity of bioactive peptides produced by enzymatic hydrolysis of skin from grass carp (Ctenopharyngodon idella)

ABSTRACTGrass carp skin pieces were homogenized in water and hydrolyzed by Alcalase®, collagenase, proteinase K, and/or trypsin at their optimum conditions. Samples were taken at various degrees of hydrolysis and were evaluated for antioxidant, antimicrobial, and angiotensin-converting enzyme inhibitory activities. Alcalase and collagenase completely hydrolyzed the skin with different rates, and released peptides with antioxidant and angiotensin-converting enzyme-inhibitory activity. These activities increased linearly with increasing degrees of hydrolysis. Subsequent incubation of the collagenase hydrolysates with trypsin slightly increased the antioxidant activity. Proteinase K, although only partially hydrolyzing the skin, also catalyzed the release of peptides with antioxidant and angiotensin-converting enzyme-inhibitory activities. These results show that skin by-products from grass carp can be a source of bioactive peptides produced by a one-step reaction. Such hydrolysates may be applied in food products to prolong shelf life and provide beneficial effects on blood pressure.

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 (kd/kh), 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.

Functional properties of pea protein hydrolysates in emulsions and spray-dried microcapsules

In the present study the impact of partial enzymatic hydrolysis on the functional properties of pea protein isolate (PPI) was investigated. PPI and pea protein hydrolysates (PPH) with various degrees of hydrolysis (DH) were characterised by molecular weight distribution, interfacial activity and dilatational rheology (pendant drop tensiometry) and emulsion properties (oil droplet size and ζ-potential). Their suitability for the microencapsulation of nutritional oils by spray-drying and prevention of hydroperoxide formation during storage was evaluated. Only at very low DH (1%), could stable emulsions be produced using alcalase PPH as emulsifier, most likely due to enhanced bulk aggregation, however the oil droplet size was increased compared to PPI-stabilised emulsions. In contrast, trypsin PPH-stabilised emulsions exhibited smaller oil droplets and an increased surface charge (ζ-potential) with increasing DH in comparison to PPI-stabilised emulsions. Differences observed were reflected in dilatational rheological experiments. Depending on the enzyme used to produce PPH, the dilatational moduli increased and the phase angle decreased (trypsin), i.e. stronger and more elastic interfacial layers were formed, or vice versa (alcalase). The PPI- and trypsin-derived PPH-containing emulsions were stable during atomisation and drying, resulting in high microencapsulation efficiencies (94.5–95.6%). Trypsin PPH exhibited a higher potential than PPI to reduce lipid oxidation of rapeseed oil in spray-dried emulsions during storage as demonstrated by hydroperoxide formation. This effect may be attributed to the altered physical properties of the interfacial film as well as the antioxidative effects of the hydrolysed proteins.

Developing a potential prebiotic of yogurt: growth of Bifidobacterium and yogurt cultures with addition of glycomacropeptide hydrolysate

SummaryThis study is aimed at investigating the feasibility of casein glycomacropeptide (GMP) hydrolysates as potential prebiotics in yogurt. The growth performance of Bifidobacterium animalis subsp. lactis (Bb12) was determined in the presence of GMP hydrolysates produced by the action of proteolytic enzymes (trypsin and papain) with various degrees of hydrolysis. The growth‐promoting effect of GHP on Lactobacillus bulgaricus and Streptococcu thermophilus were also evaluated. Results showed that the optimum hydrolysis time of GMP with trypsin or papain for Bb12 growth promotion was 2 and 0.5 h, respectively. Compared with GMP and its trypsin hydrolysate, the GMP hydrolysate produced with papain (GHP) was the best for Bb12 growth, which obtained the highest viable count (9.3 log cfu mL−1) and the lowest pH of 4.69. The obtained GHP significantly improved the growth of S. thermophilus (P &lt; 0.05), while it had little effect on the growth of L. bulgaricus (P &gt; 0.05)., The viable count of Bb12 of the yogurt obtained with the addition of 1.5% GHP was about four times higher than that of the control without GHP addition. The growth‐promoting effect of GHP might be related to its high content of Glu, Leu and Ala while had no direct relationship with sialic acid content.

Antioxidant activities of rice bran protein hydrolysates in bulk oil and oil-in-water emulsion.

Recently, utilization of natural antioxidants in food processing has been of growing interest, owing to the concerns of health hazards of synthetic agents. Protein hydrolysates are a potent candidate for this purpose. In this work, rice bran protein hydrolysates (RBPH) with various degrees of hydrolysis (DH) were prepared, and their antioxidant activities in soybean oil and oil-in-water (O/W) emulsion were examined. With increasing DH, RBPH showed increasing antioxidant activities, as evidenced by the increases in DPPH radical scavenging activity, reducing power and ferrous chelating activity (P < 0.05). The improved activity was associated with increasing surface hydrophobicity (SoANS). After hydrolysis for 60 min, the content of hydrophobic amino acids was increased. When RBPH with various DH were incorporated into bulk soybean oil and O/W emulsion stored at 37 °C for up to 15 days, lipid oxidation was successfully retarded, especially when DH increased. The efficiency in prevention of oxidation was dose dependent (0-10 g L(-1)), as indicated by the lower peroxide value and thiobarbituric reactive substances. The present work suggests that RBPH might be potently employed as a natural antioxidant in both bulk oil and emulsion models.

Chemical–physical behavior of hydrogels of poly(vinyl alcohol) and poly(ethylene glycol)

New hydrogels based on polyethylene glycol (PEG) and poly(vinyl alcohol) (PVA) of different degrees of hydrolysis were synthesized. To form the network the PEG was modified at their ends with acyl chloride groups to be used as the crosslinking agent. The compositions of the hydrogels were between 50% and 90% by weight of PEG and PVA of various degrees of hydrolysis were used. It was found that the degree of hydrolysis of the PVA and the PEG content influence the equilibrium water content of the hydrogel. The process of swelling of all the hydrogels prepared followed a second-order kinetics.The pH of the medium influences the rate and degree of hydration of the hydrogel, this influence being less noticeable at lower pH values. At pH of 7.0 and above because the hydrolysis of the ester bonds which act as crosslinking points the swelling increases noticeably. The rate of hydrolysis of the hydrogels is greatly influenced by the degree of hydrolysis of the PVA used in their synthesis.The degree of hydration decreases with temperature because their entropy of mixing is negative; however, when the pH of the medium favors the process of hydrolysis, an increase in temperature accelerates this process, which causes a progressive increase in their degree of hydration.

EFFECT OF PROTEASE PRETREATMENT ON THE FUNCTIONAL PROPERTIES OF PROTEIN CONCENTRATE FROM DEFATTED PEANUT FLOUR

ABSTRACTPeanut protein concentrate (PPC) was extracted from commercial defatted peanut flour (DPF) after protease pretreatment. The effect of proteolysis by Alcalase 2.4 L, papain and Protamex at various degrees of hydrolysis (DHs; 1–8%) on the yield and functional properties of PPC were investigated. Proteolysis remarkably increased the nitrogen solubility of DPF in acidic and basic conditions. Enzymatic degradation of denatured and insoluble proteins in DPF was mainly responsible for the increase of nitrogen solubility index. Compared with the control, the yield of PPC was significantly increased by enzymatic pretreatment. In terms of the functional properties, PPCs prepared by papain and Protamex at 4% or 8% DH had high emulsifying activity index. For all three enzymatic treatments, foaming capacity and foaming stability were significantly improved at various DH (P &lt; 0.05). This study demonstrated that protease pretreatment was a highly effective way to extract PPC with good functional properties from DPF.PRACTICAL APPLICATIONSPeanut is an important oilseed crop and a well‐accepted food. After oil production through thermal treatment, the defatted peanut flour is the main by‐product, which possesses large amount of proteins. However, due to the low extraction yield and poor functional properties of these proteins, they are not well utilised in industry till now. In this work, protease was used to pretreat defatted peanut flour. The results indicated that this pretreatment could improve the yield and functional properties of peanut proteins. Functional properties of food proteins are important in food processing and food product formulation. Peanut protein with good emulsifying and foaming properties would have a potential application in some food system, such as salad dressing, sausages, bologna, soups, confectionery, frozen desserts and cakes and so on. Therefore, this work is helpful for extensive utilisation of peanut proteins.

Influence of casein hydrolysates on the growth and lactic acid production of Lactobacillus delbrueckii subsp. bulgaricus and Streptococcus thermophilus

SummaryThe growth performance of Lactobacillus delbrueckii subsp. bulgaricus (L. bulgaricus) and Streptococcus thermophilus (S. thermophilus) was determined in the presence of casein hydrolysates produced by the action of five proteolytic enzymes (Alcalase, Flavorzyme, Neutrase, Papain and Trypsin) with various degrees of hydrolysis (DH). In addition, these five kinds of casein hydrolysates were fractionated by ultrafiltration and the influence of the amino acid composition of the peptides on the growth and lactic acid yield of yoghurt lactic acid bacteria (LAB) was studied. The results showed that the ultrafiltered fraction (&lt;3000 Da) was the determinant stimulator in crude hydrolysates. Furthermore, the hydrophilic amino acid residua including His, Lys, Glu and Ser were beneficial for bacterial growth. Compared with control, the cell growth and lactic acid yield of yoghurt LAB were increased with the supplementation of the peptides fraction (&lt;3000 Da) produced with papain by 65.1% and 49.6%, respectively.

Influence of the rapeseed protein hydrolysis process on CHO cell growth

Different protein hydrolysates were prepared from enzymatic hydrolyses of a rapeseed isolate (>90% protein content) using different commercial enzymes of non-animal origin. The extent of hydrolysis was controlled to produce hydrolysates corresponding to various degrees of hydrolysis (DH) from 5 to 30. These hydrolysates were characterized according to their solubility and size peptide pattern. Different growth behaviours of Chinese Hamster Ovary cells were observed when these various hydrolysates were added in serum-free medium containing transferrin, albumin and insulin. Hydrolysates from low degree of hydrolysis generally did not exhibit significant positive effect on cell growth; conversely hydrolysates from extensive hydrolysis, corresponding to a major low molecular size peptides content, usually allowed an increase of the maximal cell density. However, depending on the enzyme used, the supplementation with hydrolysates corresponding to a high degree of hydrolysis and composed of at least 70% peptides with a molecular size under 1kDa, led to different maximal cell density values, indicating the importance of enzyme specificity and consequently the nature of the released peptides. This result showed that the positive influence of the rapeseed hydrolysates on cell growth was not only due to a nutritional support tied to the addition of small peptides but may be related to the presence of peptides exhibiting growth or survival factor effects. Furthermore, total substitution of proteins (transferrin, albumin and insulin) in the cell culture medium by some rapeseed hydrolysates appeared to be a promising alternative to improve the cell growth in protein-free media.

Peptides with angiotensin I-converting enzyme (ACE) inhibitory activity from defibrinated, hydrolyzed bovine plasma.

Defibrinated bovine plasma (DBP) was treated with the microbial protease Flavourzyme to obtain protein hydrolysates with various degrees of hydrolysis (DH). The angiotensin I-converting enzyme (ACE) inhibiting activity of the hydrolyzed protein was assessed with hippuryl-His-Leu as the substrate. The amount of hippuric acid released, due to uninhibited ACE activity, was determined by high-performance liquid chromatography. ACE inhibiting (ACEI) activity was found to increase with increasing DH; the 43% DH hydrolysate exhibited the highest activity and had an IC(50) of 1.08 mg/mL. Peptide fractions with high ACEI activity were isolated using size exclusion chromatography. The fraction that possessed the highest ACEI activity contained peptides with GYP, HL(I), HPY, HPGH, L(I)F, SPY, and YPH sequence motifs, as determined by reversed-phase liquid chromatography-tandem mass spectrometry using a novel immonium precursor-ion scanning technique. Some of these motifs correspond to sequences found in bovine serum albumin, a potential source of ACEI peptides in bovine plasma.

Qualitative Analysis of the Stability of the Oxazine Ring of Various Benzoxazine and Pyridooxazine Derivatives with Proton Nuclear Magnetic Resonance Spectroscopy

AbstractA series of 3,4‐dihydro‐1,3‐benzoxazine and 3,4‐dihydro‐1,3‐pyridooxazine derivatives was synthesized, and the hydrolysis of the derivatives was studied with proton nuclear magnetic resonance spectroscopy. The oxazine derivatives underwent various degrees of hydrolysis when H2O was added to dimethyl sulfoxide solutions of the compounds. The rates and extents of decomposition of the oxazine ring systems depended on the electronic effects of substituents within the molecules. Examination of the proton nuclear magnetic resonance spectra that were generated during decomposition of the oxazines and trends in stability of the oxazine derivatives suggest the formation of an intermediate in the hydrolysis mechanism.

Copolymerization of acrylonitrile, methyl acrylate, and itaconic acid in thiocyanate solutions in the presence of hydrolyzed nitron fibre waste

-- The kinetics of the copolymerization process of AN, MA, and IA in the presence of hydrolyzed Nitron fibre characterized by various degrees of hydrolysis has been studied. It has been found that introducing H-PAN into the reaction mixture leads to an increase in degree of conversion in the copolymerization process and to an increase in molecular weight of the copolymer synthesized.

Preparation of potentially electroactive thallium polymers derived from the acidic copolymers of maleic anhydride

Maleic anhydride copolymers with vinyl ethyl ether and N-vinyl-2-pyrrolidone were prepared in tetrahydrofuran at 60°C, using AIBN as initiator. Copoly (MA-VEE) was hydrolysed to various degrees of hydrolysis and the extent of hydrolysis monitored by i.r. Various acidic derivatives of copoly (MA-VEE), copoly(MA- N-vinyl-2-pyrrolidone) and copoly(MA-ethylene) were prepared and characterized by elemental analysis and spectroscopy. The inter- and intramolecular crosslinking of carboxylic groups in copoly(succinic acid-VEE) were studied by g.p.c. Also thallium (III) derivatives of several acidic polymers were prepared and characterized.

The Effect of Temperature on Gelation Time for Polyacrylamide/Chromium (III) Systems

Abstract Gelled polymers are being applied to modify the movement of injected fluids in the vicinity of injection and production wells in secondary and enhanced oil-recovery projects. One approach to gelation is to form a bulk gel in situ by injecting a slug of a Polyacrylamide polymer solution containing chromium(VI) followed by a polymer slug containing a reducing agent such as sodium bisulfite. Upon mixing, CR(VI) is reduced to Cr(III), and in the subsequent reaction a gel is formed. The gelation time controls the volume of fluid that can be injected in the treatment and thus is an important variable in the process. Gelation time is known to be a function of the concentration of the reactants (chromium ion, reducing agent, and polymer) as well as the polymer type, and some data relating these variables to gelation time have been reported. Another variable affecting the reaction rate is temperature, but no data relating gelation time and temperature have been published. The purposes of the work described in this paper were to obtain experimental data on the effect of temperature on gelation time for typical polyacrylamide/Cr(III) gel systems over the range of temperatures commonly encountered in reservoirs and to develop a method of correlating the data. Gelation times were measured for five different polymers, including polymers with various degrees of hydrolysis and polymers with nonionic, anionic, and cationic character. The temperature range was 25 to 80°C. Polymer, metal ion, and redox system concentrations and salinity also were varied. It was determined that, for a given polymer-reducing agent system at a specified concentration, the gelation time decreases as temperature is increased. The data were correlated in a manner analogous to the Arrhenius method of correlating chemical reaction rate data. That is, plots of the logarithm of gelation time vs. the reciprocal of the absolute reaction temperature were linear over the temperature range studied. By use of a simple nth-order reaction rate model, the slope of the Arrhenius-type plot was related to activation energy. These activation energies were found to vary only slightly for the polymer systems and concentrations investigated. The results have direct application in the design of gel treatments for injection or production wells. The correlation method provides a way of predicting the effect of temperature on the time required for a given system to gel. It is recognized that in field applications factors beyond the scope of data taken in this paper may affect the gelation process.