Enzymatic fat hydrolysis and synthesis

The hydrolysis of tallow, coconut oil and olive oil, by lipase fromCandida rugosa, was studied. The reaction approximates a firstorder kinetics model. Its rate is unaffected by temperature in the range of 26–46 C. Olive oil is more rapidly hydrolyzed compared to tallow and coconut oil. Hydrolysis is adversely affected by hydrocarbon solvents and a nonionic surfactant. Since amounts of fatty acids produced are almost directly proportional to the logarithms of reaction time and enzyme concentration, this relationship provides a simple means of determining these parameters for a desired extent of hydrolysis. All three substrates can be hydrolyzed, almost quantitatively, within 72 hr. Lipase fromAspergillus niger performs similarly. The lipase fromRhizopus arrhizus gives a slow hydrolysis rate because of its specificity for the acyl groups attached to the α-hydroxyl groups of glycerol. Esterification of glycerol with fatty acid was studied with the lipase fromC. rugosa andA. niger. All expected five glycerides are formed at an early stage of the reaction. Removal of water and use of excess fatty acid reverse the reaction towards esterification. However, esterification beyond a 70% triglyceride content is slow.     

Enzymatic hydrolysis of autohydrolyzed barley husks

BACKGROUND: Barley husks were subjected to non‐isothermal autohydrolysis of different severities, yielding a liquid phase rich in hemicellulose‐derived compounds and a solid phase, composed mainly of cellulose and lignin. This solid phase was subjected to enzymatic hydrolysis in order to assess the effects of severity on the susceptibility of substrates to enzymatic hydrolysis. The effects of the liquid to solid ratio (LSR, in the range 6 to 18 g g^?1) and cellulase to substrate ratio (CSR, in the range 3.3 to 8.2 FPU g^?1) on the enzymatic hydrolysis were assessed. RESULTS: Up to 25.8 g oligomers per 100 g raw material were present in liquors from the hydrothermal processing. Enzymatic hydrolysis of solid phases obtained under selected conditions (log Ro = 4.14, LSR = 6 g g^?1 and CSR = 5.8 FPU g^?1) yielded glucose concentrations up to 67 g L^?1 (corresponding to cellulose to glucose conversions close to 100%). CONCLUSION: It was shown that autohydrolysis is an effective method for improving the enzymatic susceptibility of barley husks. High cellulose conversions resulting in high glucose yields were achieved by enzymatic hydrolysis at low LSR and CSR. The liquid fraction obtained upon autohydrolysis contained large amounts of hemicellulose‐derived compounds. Copyright © 2010 Society of Chemical Industry     

青霉素菌丝中蛋白质酶法水解工艺

采用碱热法溶解青霉素菌丝,研究酶法催化水解菌丝溶解液中蛋白质转化为氨基酸的过程.考察酶种类、溶解液pH值、酶与蛋白质质量比、反应温度和时间等因素对蛋白质水解度的影响,建立最佳水解工艺.结果 表明,酶种类、酶与蛋白质之比、pH、温度和时间均对蛋白质水解过程产生影响.以单酶为催化剂,碱性蛋白酶催化水解效果最好,蛋白质水解度...     

Enzymatic hydrolysis of polyester based coatings

The potential of two hydrolytic enzymes, namely a lipase from Thermomyces lanuginosus (TlL) and a cutinase from Humicola insolens (HiC) for hydrolysis of the phthalic acid backbone based polyester coatings was assessed. Two phthalic acid/trimethylolpropane based model substrates resembling the structure of the polyester backbone of coatings were synthesized. Out of both enzymes, only the cutinase was able to hydrolyze both model substrates while the larger substrate was hydrolyzed at a lower rate. The cutinase was also able to hydrolyze a coating (alkyd resin) both in suspension and as dried film. LC–MS analysis of the hydrolysis products released from the coating revealed the presence of oleic acid, its monoglyceride, phthalic acid and 2-((3-((2-((2,3-dihydroxypropoxy)carbonyl)benzoyl)oxy)-2-hydroxypropoxy)carbonyl)benzoic acid. These results indicate that the enzyme was able to hydrolyze the polyester backbone as well as to release fatty acid side chains. Consequently, enzymatic hydrolysis has a potential for the removal of coatings, their recycling or their functionalization.     

Enzymatic hydrolysis of long-chainN-heterocyclic fatty esters

Incubation of a 1-pyrroline ester [viz. methyl 8-(5-hexyl-1-pyrroline-2-yl)octanoate,1] with bakers' yeast (Saccharomyces cerevisiae) gave the corresponding free fatty acid (1a, 52%). The C=N bond of the 1-pyrroline was not reduced by the yeast. Complete hydrolysis of compound1 was successful using lipase ofCandida cylindracea (CCL) or Lipolase (Rhizomucor miehei) under stirred or ultrasound condition. Fatty esters containing a pyrrolidine [viz. methyl 8-(cis/trans-5-hexyl-pyrrolidine-2-) octanoate,2] orN-methyl pyrrolidine [viz. methyl 8-(cis-5-hexyl-N-methyl-pyrrolidine-2-)octanoate,3] system in the alkyl chain were not hydrolyzed by either CCL or Lipolase, unless conducted in an ultrasonic bath. The hydrolytic activities of the enzymes appeared to be strongly affected by the stereochemistry of theN-heterocyclic ring system. Chemical hydrolysis of compounds1–3 gave the corresponding fatty acidN-HCl salts.     

纤维素的酶水解糖化

纤维素为自然界存在最多的再生有机资源，能水解成葡萄糖，加工成食品、燃料、化工产品等。酸和酶都能催化水解，但酶法效果好，所得水解液的纯度高。多年来对于纤维素的酶法水解研究工作很多，但还有若干问题有待解决，尚未发展成适于工业生产应用的好工艺。本文扼要地综述纤维素的酶水解机理和纤维素物料的应用工艺。纤维素酶系内切葡聚糖酶、外切葡聚糖酶和β-葡萄糖甙酶的混合物，这三种酶协同起水解作用。纤维素物料不纯，还有伴生物半纤维素和木质素共同存在，需要预先处理，破坏纤维素的结晶性，提高水解效能，分离开半纤维素和木质素，加以好的利用，提高经济效益。     

Enzymatic hydrolysis of rawhide using papain and neutrase

Rawhide split was hydrolysed separately by two proteolytic enzymes, papain and neutrase. The effects of enzymatic conditions of the hydrolysis reaction were investigated. During the first 10 min of the enzymatic hydrolysis, the yield of the hydrolysed protein increased sharply, then it slowly increased or became essentially constant due to the limited availability of the substrate. The optimum hydrolysis conditions of papain and neutrase for highest protein yield are at 70 °C, pH 6–7 and 40–50 °C, pH 6–7, respectively. The product from papain hydrolysis is a gelatin with low gel strength and viscosity, while that from neutrase hydrolysis is collagen hydrolysate with viscosity as low as water. This is considered to indicate that longer fragments of protein are obtained from papain hydrolysis than that from neutrase implying different mechanisms of papain and neutrase hydrolysis.     

Enzymatic hydrolysis of canola oil with hydrodynamic cavitation

A hydrodynamic cavitation system based on a venturi was used to test the effectiveness of cavitation for enhancing the enzymatic hydrolysis of canola oil using lipase from Candida rugosa. Cavitation led to the production of fine oil-in-water and water-in-oil emulsions with the enzyme in the water phase. Using venturi inlet pressures of up to 8 bar, the yield of fatty acids was only about 60% of the maximum possible. In contrast, a simple stirred batch reactor produced over 90% of the maximum possible yield with reaction rates equal to, or better than, those obtained in a cavitating system. It was concluded that cavitation inhibited the reaction in some way and is not effective for intensification of hydrolysis.     

Enzymatic hydrolysis pretreatment for mechanical expelling of soybeans

Mechanical expelling of soybeans with enzymatic hydrolysis as pretreatment was investigated, and the process parameters were optimized by means of response surface methodology. Enzyme pretreatment enhanced both the amount of extractable oil in soybeans and oil extractability. A second-order response surface model was developed to predict the expelled oil as a function of the six process parameters investigated. The optimum was found at: Moisture content during hydrolysis, 23.00% wet basis (w.b.); enzyme concentration, 11.84% vol/wt; incubation period, 13.24 h; moisture content during pressing, 9.36% w.b.; pressing pressure, 75 MPa; and pressing time, 5.36 min. The parameters had no interactive effects on expelled oil. Pressing pressures above 75 MPa caused extrusion. Under the optimal conditions, oil expelled from dehulled cracked soybeans by static pressing at room temperature (18°C) was 63.5% of the total extractable oil. Much higher oil recovery would be expected in actual screw expellers due to dynamic pressing and higher operating temperature. Oil recovery could be further increased by adding one or more conventional pretreatments to the enzymatic hydrolysis pretreatment investigated in this study.     

Enzymatic hydrolysis at an oil/water interface

Triglycerides are metabolized by most of the organs and tissues of the body. However, the conditions in the lumen of the intestinal tract are unique, for it is only here that triglycerides are metabolized in the free state. Elsewhere these lipids are associated with water-soluble materials. Since the substrate is water-insoluble and the enzyme is water-soluble, lipase, which brings about the hydrolysis of triglycerides in the intestinal tract, has the special property of being capable of functioning efficiently at an oil/water interface. Any material that can alter the nature of this oil/water interface can markedly influence the digestion of triglycerides. Because of the unusual conditions under which the hydrolysis of triglycerides occurs, the usual methods of studying enzyme kinetics are not applicable. Besides the enzyme-substrate reaction itself, one must consider also such matters as diffusion of the substrate to the oil/water interface, removal of the products of hydrolysis from the oily/water interface, and the subsequent diffusion of these into the bulk phase. All of these steps can be influenced by such variables as efficiency of agitation, electrolyte concentration, and the presence of surface-active agents, such as monoglycerides, soaps, and the bile salts.     

Enzymatic hydrolysis of nylon 6 fiber using lipolytic enzyme

This study confirms the structural changes of nylon 6 fibers using lipase by measuring the dyeability, hydrophilicity, chemical changes, and fastness properties. For this purpose, nylon 6 fabrics were first treated separately with different concentrations of lipase enzyme. The dyeing process was then carried out on the treated fabrics with two disperse and acid dyes. A UV‐vis spectrophotometer was used for determination of dyebath exhaustion. Acid and disperse dyes showed higher dyebath exhaustion on the enzyme treated samples compared to raw material. The intensity of major peaks in FTIR spectra of the lipase treated samples are in favor of chemical changes of the polypeptide functional groups in fabric. Tensile strength of treated fabrics was decreased due to enzyme treatment. The results of color measurements in the CIELAB system showed that the darkness of the samples increased with an increase in the enzyme percentage in the solution. The results of moisture regain showed that treatment of nylon fabrics with lipolytic enzymes caused to increase the moisture absorbency. The wash and light fastness properties of samples were measured according to ISO 105‐CO5 and Daylight ISO 105‐BO1 and discussed. © 2010 Wiley Periodicals, Inc. J Appl Polym Sci, 2010     

Enzymatic hydrolysis in vitro of thermally oxidized sunflower oil

The hydrolysis of thermally oxidized sunflower oil by pancreatic lipase was studied in relation to chemical changes in the acylglycerols. Four classes of compounds (monomers, dimers, trimers and polymers) formed from the acylglycerols were separated from the heated oils by column chromatography on silica gel, and further verified by thin layer chromatography. Each fraction, after analyses for generaly properties, was subjected to a time course study of hydrolysis by pancreatic lipase over a 30-min period. After 70 hr of heating, the amount of hydrolysis for the acylglycerol dimers was only about half that of the monomers, and that for the trimers was, in turn, about one-third that of the monomers. The polymers were the least hydrolyzed and showed no further reaction after 5 min. The reduction in enzymatic hydrolysis of isolated fractions from the thermally oxidized oils indicates structural differences, related to formation of polar compounds and polymerization products. Adverse effects on animals from feeding these materials can be attributed partly to inhibition of hydrolysis resulting in less available energy.     

Enzymatic enantioselective hydrolysis of acyloxyferrocenophanes using lipases and esterases

Enantioselective hydrolysis of racemic acetate or butyrates of 1-hydroxy [3](1,1′) ferrocenophane and endo-1-hydroxy [4](1,2) ferrocenophane using lipases, pig liver esterase and horse liver esterase resulted in the formation of (R)-alcohols and (S)-esters.     

Enzymatic hydrolysis of extruded-expelled soy flour and resulting functional properties

Limited hydrolysis (4% degree of hydrolysis) of extruded-expelled soy flour protein (protein dispersibility index=21) that was poor in solubility and other functional properties was evaluated at pilot-plant scale (5 kg of flour) with two endopeptidases and one exopeptidase. Some hydrolysates were merely spray-dried whereas others were jet-cooked at 104°C for 19 s before spray-drying. Solubility, emulsification capacity and stability, foaming capacity and stability, apparent viscosity, and sensory attributes were then characterized. The type of protease used and hydrothermal cooking affected functional and sensory properties. Protein solubility modestly increased with hydrolysis and jet cooking, but emulsification capacity decreased on hydrolysis and was not restored with hydrothermal cooking. Emulsion stability improved in the endopeptidase hydrolysates, but not in the exopeptidase hydrolysates. The foaming capacities of the hydrolysates for both types of enzymes were better than for the unhydrolyzed control. Highly stable foams were obtained after hydrolyzing with exopeptidase and hydrothermal cooking. Ten percent protein hydrolysate dispersions showed large losses in consistency coefficient apparent viscosity, which increased significantly with hydrothermal cooking only for the unhydrolyzed control. Difference-from-control sensory evaluation indicated that both jet-cooked and non-jet-cooked enzyme hydrolysates were different from unhydrolyzed controls.     

Enzymatic hydrolysis and detection of 3-monochloropropane-1,2-diol esters

There are more and more studies on the detection method of 3-chloro-1,2-propanediol fatty acid esters (3-MCPD esters) at present, by comparing these methods for the determination of 3-MCPD esters. Indirect methods, which determine total amount of 3-MCPD after hydrolysis of the esters, have an advantage over direct methods. The existing indirect methods, however, may yield unreliable results or require long hours of alkaline methanolysis. In contrast, the indirect enzymatic hydrolysis method has mild conditions and more accurate results. In this study, we developed a reliable and rapid indirect method for determination of 3-MCPD esters. 3-MCPD esters were enzymolysis to 3-MCPD by indirect enzymatic hydrolysis method, and the conditions of enzymatic hydrolysis were optimized, the content of 3-MCPD after enzymatic hydrolysis was detected by gas chromatography–mass spectrometry (GC–MS) and the yield was calculated. Finally, the optimum conditions for enzymatic hydrolysis of 3-MCPD esters were determined. According to the optimal enzymatic hydrolysis condition, the contents of 3-MCPD esters in four food oils were determined. The method is simple and sensitive and can meet the requirement of 3-MCPD esters detection in general oils.     

Enzymatic hydrolysis and fermentation of lime pretreated wheat straw to ethanol

BACKGROUND: The objective of this work is to develop an efficient pretreatment method that can help enzymes break down the complex carbohydrates present in wheat straw to sugars, and to then ferment of all these sugars to ethanol. RESULTS: The yield of sugars from wheat straw (8.6%, w/v) by lime pretreatment (100 mg g^?1 straw, 121 °C, 1 h) and enzymatic hydrolysis (45 °C, pH 5.0, 120 h) using a cocktail of three commercial enzyme preparations (cellulase, β‐glucosidase, and xylanase) at the dose level of 0.15 mL of each enzyme preparation g^?1 straw was 568 ± 13 mg g^?1 (82% yield). The concentration of ethanol from lime pretreated enzyme saccharified wheat straw (78 g) hydrolyzate by recombinant Escherichia coli strain FBR5 at pH 6.5 and 35 °C in 24 h was 22.5 ± 0.6 g L^?1 with a yield of 0.50 g g^?1 available sugars (0.29 g g^?1 straw). The ethanol concentration was 20.6 ± 0.4 g L^?1 with a yield of 0.26 g g^?1 straw in the case of simultaneous saccharification and fermentation by the E. coli strain at pH 6.0 and 35 °C in 72 h. CONCLUSION: The results are important in choosing a suitable pretreatment option for developing bioprocess technologies for conversion of wheat straw to fuel ethanol. Copyright © 2007 Society of Chemical Industry     

不同结晶度纤维素的酶解历程的SEC-MALLS研究(英文)

The reactions of exo-cellulase (cellobiohydrolase, CBH) and endo-cellulase (endoglucanase, EG) were investigated by analyzing the insoluble residues of microcrystalline cellulose (MCC) and filter paper cellulose (FPC) during enzymatic hydrolysis. Molecular parameters including molecular weight and its distribution, degree of po-lymerization, and radii of gyration were measured by size exclusion chromatography coupled with multi-angle laser light scattering. No significant change in MCC chains was found during the whole reaction period, indicating that CBH digestion follows a layer-by-layer solubilization manner. This reaction mode might be the major reason for slow enzymatic hydrolysis of cellulose. On the other hand, the degree of polymerization of FPC chains decreases rapidly in the initial reaction, indicating that EG digestion follows a random scission manner, which may create new ends for CBH easily. The slopes of the conformation plots for MCC and FPC increase gradually, indicating stronger chain stiffness of cellulose during hydrolysis.     

Enzymatic hydrolysis of dissolved corn stalk hemicelluloses: reaction kinetics and modeling

The enzymatic hydrolysis of hemicelluloses as a filtrate originating from aqueous/steam pretreated corn stalks was carried out using commercial enzyme systems of several activities composed of cellulases and β‐D ‐xylosidases from Aspergillus niger. The hydrolysis was conducted using free enzymes in aqueous substrate solution at a temperature of 30 °C and a pH of 5. Saccharification corresponding to 90% of potential simple sugar release was obtained after 10 h using 0.12 activity units (U) of Cellulases_1 complex per mg of dissolved solids present in the filtrate. Synergetic action of Cellulases_1 enzyme complex and β‐D ‐xylosidases proved to be effective for the hydrolysis of plant hemicelluloses. A lumped model based on the Michaelis–Menten approach successfully described the fate of the lumped variables describing the hydrolysis of the overall kinetics of corn stalk hemicelluloses. The maximum saccharification rate evolved with the cellulases concentration as . This overall and pseudokinetic tendency was comparable to those reported in the literature for more simple systems employing a defined substrate and a pure hydrolytic enzyme. The n‐value was found to be in the range of 0.1–0.9 depending on the substrate lump involved in the reaction system. Copyright © 2003 Society of Chemical Industry     

Enzymatic hydrolysis of oat and soya lecithin: Effects on functional properties

Enzymatic hydrolysis of oat and soy lecithins and its effects on the functional properties of lecithins were investigated. The phospholipase used was most efficient at low enzyme and substrate concentrations. More fatty acids were released from soy lecithin than from oat lecithin. The maximum degree of hydrolysis was 760 μmol free fatty acids per gram soy lecithin and 170 μmol free fatty acids per gram oat lecithin. On the basis of the total carbohydrate and phosphorus contents in the polar fractions of the lecithins, oat lecithin contained more glycolipids and less phospholipids than soy lecithin. With regard to functional properties, the stability of oil-in-water emulsions was enhanced by hydrolyzed soy lecithin and by crude and hydrolyzed oat lecithins, but only hydrolyzed soy lecithin prevented the recrystallization of barley starch. The dissociation enthalpy of amylose-lipid-complex (AML-complex) was significantly higher when hydrolyzed soy lecithin was present. Hydrolyzed oat lecithin slightly affected the dissociation enthalpy of AML-complex. The other lecithins had no effect on recrystallization or dissociation enthalpies in the barley-starch matrix.