Inactivation Of Lipase Research Articles

Oat Kilning and Its Effects on Liquid Oat-Base Production.

The aim of this study was to give insights on the effects of an industrially relevant kilning method, with a focus on lipase inactivation and oat-base production. Storage of non-kilned, dehulled oat kernels in either room temperature or at 37 °C for up to 64 days led to increasing lipase activity with time, despite a decrease in moisture content and water activity, demonstrating the importance of kilning before storage. It was shown that the temperature and relative humidity used during the kilning had a major impact on both protein solubility and lipase inactivation. Steaming with saturated steam at 90 °C for 30 min followed by drying at 100 °C for 30 min was found to be enough to inactivate all lipases but still leave a relatively high protein solubility (42% of the total soluble protein). In the sensory trial, the indication was that kilning was a vital step from a sensory quality perspective, giving a pleasant aroma to the final oat-base product. However, with kilning, the final protein content decreased; thus, these results are important for the development of future oat-base products, where quality, nutritional content, and taste need to be balanced.

Inactivation of lipase and lipoxygenase in whole wheat flour using atmospheric cold plasma and steam treatments: Kinetics, mechanism, and impact on its compositional properties

This study aims to utilize two separate techniques, viz., atmospheric cold plasma (voltage: 5–25 kV; time: 1–10 min) and steam treatments (at 100 °C for 1–4 min), to inactivate lipase and lipoxygenase in whole wheat flour (WWF) and assess the impact on its compositional properties. The cold plasma exposure of WWF at 25 kV/6 min resulted in 97.5% and 100% inactivation in lipase and lipoxygenase activity, respectively, whereas corresponding inactivation values after the steam treatment (100 °C/4 min) were 90.6% and 99.7%. The inactivation order (n) of lipase and lipoxygenase during cold plasma treatment was 1.2 and 1.0, respectively. In the optical emission spectra of cold plasma-induced air, the band heads within 328–426 nm confirmed the transition between various reactive nitrogen species (second positive, first negative, second positive, and mono-positive systems). The band-head for OH radicals was recorded at 314 nm. The oxygen molecular band at 739 nm and singlet oxygen transition line at 778 nm were also observed. The cold plasma and steam treatments resulted in a more random coil in lipase's secondary structure. The cold plasma treatment at 25 kV/6 min didn't impact the particle size, density, color profile, and proximate composition of the flour.

Use of thistle seeds of modified composition in chocolate mass technology

The object of the study is the analytical values of lipids of milk thistle seeds of a modified composition, namely acid and peroxide values, as well as the induction period of lipids of chocolate mass with the addition of milk thistle seeds. The paper substantiates rational parameters of thistle seed processing for the inactivation of lipases and lipoxygenases. Approximate dependences of the acid and peroxide values of thistle seed lipids on the pH of the wetting solution and the wetting degree of seeds were obtained. This makes it possible to substantiate such rational processing parameters of thistle seeds that inhibit the accumulation of free fatty acids and primary oxidation products in seeds during storage. An increase in the induction period of the oxidation of the lipid component of the chocolate mass with the use of thistle seeds of a modified composition was proven, which is 2.5 times higher than the induction period of the chocolate mass sample with thistle seeds with a native enzyme complex. The research results make it possible to develop a technology of healthy chocolate mass using thistle seeds of a modified composition, the lipid component of such mass is stable to oxidation and hydrolysis. The data obtained in the work are explained by an increase in the ability to inactivate lipolytic and lipoxygenase enzymes of milk thistle at high humidity in an acidic environment under the influence of microwave radiation. The advantage of the obtained results is the possibility of not violating the integrity of thistle seeds during the inactivation of the enzyme complex, which allows extending the shelf life of this raw material. An applied aspect of using the scientific result is the possibility of expanding the range of healthy chocolate masses with the use of thistle seeds

Influence of Supercritical Carbon Dioxide on the Activity and Conformational Changes of α-Amylase, Lipase, and Peroxidase in the Solid State Using White Wheat Flour as an Example.

Green technologies using renewable and alternative sources, including supercritical carbon dioxide (sc-CO2), are becoming a priority for researchers in a variety of fields, including the control of enzyme activity which, among other applications, is extremely important in the food industry. Namely, extending shelf life of e.g., flour could be reached by tuning the present enzymes activity. In this study, the effect of different sc-CO2 conditions such as temperature (35-50 °C), pressure (200 bar and 300 bar), and exposure time (1-6 h) on the inactivation and structural changes of α-amylase, lipase, and horseradish peroxidase (POD) from white wheat flour and native enzymes was investigated. The total protein (TPC) content and residual activities of the enzymes were determined by standard spectrophotometric methods, while the changes in the secondary structures of the enzymes were determined by circular dichroism spectrometry (CD). The present work is therefore concerned for the first time with the study of the stability and structural changes of the enzyme molecules dominant in white wheat flour under sc-CO2 conditions at different pressures and temperatures. In addition, the changes in aggregation or dissociation of the enzyme molecules were investigated based on the changes in particle size distribution and ζ-potential. The results of the activity assays showed a decrease in the activity of native POD and lipase under optimal exposure conditions (6 h and 50 °C; and 1 h and 50 °C) by 22% and 16%, respectively. In contrast, no significant changes were observed in α-amylase activity. Consequently, analysis of the CD spectra of POD and lipase confirmed a significant effect on secondary structure damage (changes in α-helix, β-sheet, and β-turn content), whereas the secondary structure of α-amylase retained its original configuration. Moreover, the changes in particle size distribution and ζ-potential showed a significant effect of sc-CO2 treatment on the aggregation and dissociation of the selected enzymes. The results of this study confirm that sc-CO2 technology can be effectively used as an environmentally friendly technology to control the activity of major flour enzymes by altering their structures.

Kinetic and thermodynamic studies on the thermal inactivation of lipase immobilized on glutaraldehyde-activated rice husk silica.

The objective of this study was to obtain sufficient information on the thermal stabilization of a food-grade lipase from Thermomyces lanuginosus (TLL) using the immobilization technique. To do this, a new non-porous support was prepared via the sequential extraction of SiO2 from rice husks, followed by functionalization with (3-aminopropyl) triethoxysilane - 3-APTES (Amino-SiO2), and activation with glutaraldehyde - GA (GA-Amino-SiO2). We evaluated the influence of GA concentration, which varied from 0.25% v v-1 to 4% v v-1, on the immobilization parameters and enzyme thermal stabilization. The thermal inactivation parameters for both biocatalyst forms (soluble or immobilized TLL) were calculated by fitting a non-first-order enzyme inactivation kinetic model to the experimental data. According to the results, TLL was fully immobilized on the external support surface activated with different GA concentrations using an initial protein load of 5mgg-1. A sharp decrease of hydrolytic activity was observed from 216.6 ± 12.4 U g-1 to 28.6 ± 0.9 U g-1 of after increasing the GA concentration from 0.25% v v-1 to 4.0% v v-1. The support that was prepared using a GA concentration at 0.5% v v-1 provided the highest stabilization of TLL - 31.6-times more stable than its soluble form at 60°C. The estimations of the thermodynamic parameters, e.g., inactivation energy (Ed), enthalpy (ΔH#), entropy (ΔS#), and the Gibbs energy (ΔG#) values, confirmed the enzyme stabilization on the external support surface at temperatures ranging from 50 to 65°C. These results show promising applications for this new heterogeneous biocatalyst in industrial processes given the high catalytic activity and thermal stability.

Current and emerging medications for the management of obesity in adults.

Current and emerging medications for the management of obesity in adults.

Lipase Inactivation Kinetics of Tef Flour with Microwave Radiation and Impact on the Rheological Properties of the Gels Made from Treated Flour

In recent years, many efforts are being made to produce tef-based food for its nutritive and health-promoting advantages. Tef grain is always whole milled because of its tiny grain size and whole flours contain bran (pericarp, aleurone, and germ) where major non-starch lipids could be deposited along with the lipid-degrading enzymes: lipase and lipoxygenase. As lipoxygenase shows little activity in low moisture, the inactivation of lipase is the common objective for most heat treatments to extend the shelf life of flours. In this study, tef flour lipase inactivation kinetics via hydrothermal treatments assisted using microwaves (MW) were studied. The effects of tef flour moisture level (12%, 15%, 20%, and 25%) and MW treatment time (1, 2, 4, 6, and 8 min) on flour lipase activity (LA) and free fatty acid (FFA) content were evaluated. The effects of MW treatment on flour pasting characteristics and the rheological properties of gels prepared from the treated flours were also explored. The inactivation process followed a first-order kinetic response and the apparent rate constant of thermal inactivation increased exponentially with the moisture content of the flour (M) according to the equation 0.048·exp (0.073·M) (R2 = 0.97). The LA of the flours decreased up to 90% under the studied conditions. MW treatment also significantly reduced (up to 20%) the FFA level in the flours. The rheological study confirmed the presence of significant modifications induced by the treatment, as a lateral effect of the flour stabilization process.

Augmentation of 2-arachidonoylglycerol signaling in astrocytes maintains synaptic functionality by regulation of miRNA-30b.

2-Arachidonoylglycerol (2-AG), the most abundant endocannabinoid, displays anti-inflammatory and neuroprotective properties. Inhibition of 2-AG degradation by inactivation of monoacylglycerol lipase (MAGL), a key enzyme degrading 2-AG in the brain, alleviates neuropathology and improves synaptic and cognitive functions in animal models of neurodegenerative diseases. In particular, global inactivation of MAGL by genetic deletion of mgll enhances hippocampal long-term potentiation (LTP) and hippocampus-dependent learning and memory. However, our understanding of the molecular mechanisms by which chronic inactivation of MAGL enhances synaptic activity is still limited. Here, we provide evidence that pharmacological inactivation of MAGL suppresses hippocampal expression of miR-30b, a small non-coding microRNA, and upregulates expression of its targets, including ephrin type-B receptor 2 (ephB2), sirtuin1 (sirt1), and glutamate ionotropic receptor AMPA type subunit 2 (GluA2). Importantly, suppression of miR-30b and increase of its targets by inactivation of MAGL result primarily from inhibition of 2-AG metabolism in astrocytes, rather than in neurons. Inactivation of MAGL in astrocytes prevents miR-30b overexpression-induced impairments in synaptic transmission and long-term potentiation (LTP) in the hippocampus. Suppression of miR-30b expression by inactivation of MAGL is apparently associated with augmentation of 2-AG signaling, as 2-AG induces a dose-dependent decrease in expression of miR-30b. 2-AG- or MAGL inactivation-suppressed expression of miR-30b is not mediated via CB1R, but by peroxisome proliferator-activated receptor γ (PPARγ). This is further supported by the results showing that MAGL inactivation-induced downregulation of miR-30b and upregulation of its targets are attenuated by antagonism of PPARγ, but mimicked by PPARγ agonists. In addition, we observed that 2-AG-induced reduction of miR-30b expression is mediated via NF-kB signaling. Our study provides evidence that 2-AG signaling in astrocytes plays an important role in maintaining the functional integrity of synapses in the hippocampus by regulation of miR-30b expression.

Effects of Lipase Immobilization Conditions and Support Materials for the Production of Structured Triacylglycerols

AbstractStructured triacylglycerols (STAG) with desired properties can be synthesized by transesterification using immobilized lipases. Herein, the effect of immobilization conditions and support material on the immobilization yield, specific activity and regioselectivity of lipases from Rhizomucor miehei (RML) and Rhizopus oryzae (ROL) in the production of STAG, are evaluated. Four different support materials utilizing adsorption and one with covalent binding are investigated. Ammonium sulfate is found to significantly increase the activity‐based immobilization yield (12% and 38% for RML and ROL, respectively) and specific activity on Accurel MP1000 (MP1000) when used as the immobilization buffer. Furthermore, the immobilization principle and support material influenced both the activity and regiospecificity. Immobilization by adsorption is found to result in higher catalytic activity, while covalent binding resulted in lipase inactivation. For RML, the highest specific activity of 43 µmol STAG min−1 g−1 (U) is obtained on MP1000, while ROL, which exhibited higher activities in general, results in a maximum activity of 120 U on Lifetech ECR8806. The obtained specific activites are comparable to the commercial preparations Novozym 40086 (45 U) and Lipase DF “Amano” IM (147 U) while the regiospecificity of the developed preparations is even higher, forming at least 64% less byproduct.Practical applications: There is an increasing need for lipids with specific nutritional and physical properties in health, nutrition, and food applications. In this context, STAG are highly promising products due to the possibility to tailor the composition to obtain the desired properties. Immobilized lipases are the catalyst of choice for the production of STAG, in which activity and regioselectivity are particularly important parameters for the process performance. In this study, it is shown that these parameters can be affected by the immobilization conditions and support material. Immobilized preparations with high activity and excellent regiospecificity are created on commercially available supports. This shows the possibility of STAG synthesis with high purity and beneficial properties.

Inhibition of 2-arachidonoylglycerol degradation enhances glial immunity by single-cell transcriptomic analysis

Background2-Arachidonoylglycerol (2-AG) is the most abundant endogenous cannabinoid. Inhibition of 2-AG metabolism by inactivation of monoacylglycerol lipase (MAGL), the primary enzyme that degrades 2-AG in the brain, produces anti-inflammatory and neuroprotective effects in neurodegenerative diseases. However, the molecular mechanisms underlying these beneficial effects are largely unclear.MethodsHippocampal and cortical cells were isolated from cell type-specific MAGL knockout (KO) mice. Single-cell RNA sequencing was performed by 10 × Genomics platform. Cell Ranger, Seurat (v3.2) and CellChat (1.1.3) packages were used to carry out data analysis.ResultsUsing single-cell RNA sequencing analysis, we show here that cell type-specific MAGL KO mice display distinct gene expression profiles in the brain. Inactivation of MAGL results in robust changes in expression of immune- and inflammation-related genes in microglia and astrocytes. Remarkably, upregulated expression of chemokines in microglia is more pronounced in mice lacking MAGL in astrocytes. In addition, expression of genes that regulate other cellular functions and Wnt signaling in astrocytes is altered in MAGL KO mice.ConclusionsOur results provide transcriptomic evidence that cell type-specific inactivation of MAGL induces differential expression of immune-related genes and other fundamental cellular pathways in microglia and astrocytes. Upregulation of the immune/inflammatory genes suggests that tonic levels of immune/inflammatory vigilance are enhanced in microglia and astrocytes, particularly in microglia, by inhibition of 2-AG metabolism, which likely contribute to anti-inflammatory and neuroprotective effects produced by inactivation of MAGL in neurodegenerative diseases.

Influence of Extraction and Pretreatment Conditions on the Yield, Solubility, and Quality of Rice Bran Oil Extracted with CO2-Expanded Hexane

Abstract Efficient, low-cost methods are required to produce impurity-free bio-oils with minimal nutrient depletion. This study investigated the effect of extraction and pretreatment conditions on the quality of rice bran oil extracted with CO2-expanded hexane. The extraction conditions considered were temperature (20–30 °C), CO2 mole fraction (0.76–0.94), and pressure (4.2–7.0 MPa). The effectiveness of rice bran hot air drying at 80–100 °C for 0.5, 1, 3, and 5 h for lipase inactivation was also studied. The rice bran oil yield and the content of free fatty acids did not depend significantly on the extraction temperature or pressure. The oil solubility increased significantly (p < 0.05) with every 5 °C increment while decreasing significantly at pressures below 5.0 MPa. The optimum extraction conditions for phosphorus-free rice bran oil (phosphorus concentrations of 9.8, 9.1, and 6.2 ppm) were CO2 mole fraction of 0.82 at 5.1 MPa and 20 °C, CO2 mole fraction of 0.87 at 5.0 MPa and 25 °C, and CO2 mole fraction of 0.92 at 5.1 MPa and 30 °C, respectively. The most effective pretreatment conditions for rice bran before storage for 10 weeks were 100 °C for 1 h. In addition, the phosphorus concentration of rice bran oil extracted with CO2-expanded hexane at a CO2 mole fraction of 0.88, 5.1 MPa, and 25 °C was ≤ 7.00 ppm, regardless of the pretreatment conditions. Therefore, CO2-expanded hexane extraction can be potentially used to produce impurity-free rice bran oil from both treated and untreated rice bran without refining.

ДУБИЛЬНЫЕ ВЕЩЕСТВА РАСТИТЕЛЬНОГО ПРОИСХОЖДЕНИЯ И НЕКОТОРЫЕ МЕХАНИЗМЫ ИХ ФАРМАКОЛОГИЧЕСКИХ СВОЙСТВ

Tannins are found in many parts of plants (fruits, bark, roots, leaves). In the chemical classification, they belong to water-soluble polyphenols. There are 2 classes of tannins: hydrolyzable (formed by polyatomic alcohol) and non-hydrolyzable (formed by condensation of phenolic compounds). Tannin derived from plants belongs to pharmacopoeia preparations. Most often in pharmacology it is used as an astringent and local anti-inflammatory agent. In addition, there is information about its antioxidant and anti-cancer properties of tannin. The mechanisms by which almost all the properties of both hydrolyzable and condensed tannins are realized are based on the regulation of the activity of the corresponding key enzymes; in most cases, this may be their activation to trigger a cascade of biochemical reactions. In addition, condensed tannins, due to their weak ability to dissolve, are able to precipitate and inactivate other substances (for example, cholesterol, external and internal antigens) due to the binding ability of gallic and tannic acids with biological molecules and prevent their excessive accumulation in the body. Some plants (for example, legumes, raspberries, persimmons, bananas) contain tannic acids with neuroprotective properties and antidepressant effects, the mechanism of which is associated with a decrease in the activity of acetylcholinesterase, as well as the effect on the activity of Na + / K+-ATPase and Ca2+- ATPase. Extracts of tannins have a hypoglycemic effect due to the inactivation of α-amylases, lipases and glucosidases; this property can be used to develop drugs for the prevention and treatment of diabetes mellitus.

Tempering–preservation treatment inactivated lipase in wheat bran and retained phenolic compounds

AbstractWheat bran is rich in functional ingredients, but the high level of lipase limits its applications. Tempering–preservation treatment (at 70–90 °C with moisture of 20%–40% for 1–4 h) was exploited for stabilising wheat bran and its effect on polyphenols was investigated. The results showed that more lipase was inactivated at higher tempering moisture, temperature and longer time. The optimum condition for inactivation of wheat bran lipase was 30% moisture and 90 °C for 4 h. The inactivation rate reached 93.8% with a residual enzyme activity of 0.264 U g−1. Under the optimum condition, the sum of free phenolic acids rose from 25.4 to 55.8 µg g−1. As for bound phenolic acids, there was a slight increase of hydroxybenzoic acid derivatives but a slight decrease of hydroxycinnamic acid derivatives. The total contents of phenolic acids before and after stabilisation were not significantly different. This study showed the possibility of using tempering–preservation as an efficient method for inactivation of wheat bran lipase while maintaining its phenolic compounds, which could be used in the production of whole wheat flour.

Mitigation of methanol inactivation of lipases by reaction medium engineering with glycine betaine for enzymatic biodiesel synthesis

Lipases are used for enzymatic production of fatty acid methyl esters (FAME/ biodiesel), an alternative fuel. However, lipases are intolerant to methanol, which is one of the substrates in the transesterification reaction to produce biodiesel. Methanol denatures lipases and thereby significantly reduces FAME yield. We have used molecular dynamics simulations to investigate methanol induced denaturation of Candida rugosa lipase and the effects of adding glycine betaine (GB), (an osmolyte), to the reaction medium, to keep lipase catalytically active in the presence of methanol. Simulation studies indicate a significant reduction in lipase denaturation, in the presence of 3 M and above concentrations of GB. The simulation results were experimentally validated by assessing FAME yield in the presence and absence of GB. Higher yields of FAME in the presence of GB confirm catalytically active lipase, indicating a stable enzyme and stabilizing action of GB on lipase in the presence of methanol. This study can therefore be regarded as a proof-of-concept to ascertain the stabilizing effect of glycine betaine, on lipase, in the presence of methanol. Furthermore, the fuel properties of the FAME synthesized were assessed by ASTM methods.

Effects of low-temperature microwave treatment of wheat germ.

Wheat germ has a great potential byproduct in food formulations for its outstanding nutritional value. To allow valorization, there is a need to inactivate endogenous enzymes such as lipases to avoid lipid oxidation. In the present study, the effects of microwaves on enzyme activity, as well as on functional and physical properties of wheat germ, were evaluated. Microwave treatments were performed at 50, 60 and 70 °C for 5-20 min. Lipase activity was severely affected at 60 and 70 °C in contrast to lipoxygenase. Microwave treatment did not cause changes in germ moisture content or color parameters. No significant changes were observed in equilibrium moisture content when comparing the adsorption and desorption processes of raw and microwave-treated wheat germ. The best model to describe sorption process was the Guggenheim-Anderson-De Boer equation. According to the dielectric properties of raw wheat germ, it could be considered as transparent to energy (ε' < 1.87 and ε'' < 0.35). Thermal analysis of proteins showed a low denaturation degree (below 35% to raw material). In addition, some functional properties were enhanced such as oil retention capacity. Conformational changes as a result of microwave treatment were associated with the slight decline observed on the monolayer moisture content. Microwave treatments of wheat germ at 60 and 70 °C were effective for lipase inactivation. Physical properties did not change drastically after the treatments. Microwave-treated wheat germ could be a good source of high-protein ingredient in food product development. © 2021 Society of Chemical Industry.

Biocatalytic transesterification of algal oil employing a heterogenous methanol tolerant lipase enzyme aggregate from Bacillus mycoides strain CV18

Methanol induced lipase inactivation is the major hindrance in commercialization of enzyme catalyzed biodiesel production. Thus, methanol tolerance is highly needed for the lipase to be used in transesterification reaction. Hence, by virtue of such desirability, a methanol tolerant, extracellular lipase FDS8(L) was extracted from Bacillus mycoides strain CV18 and purified to homogeneity with 22.3 % yield. It was a non-position specific, alkaline lipase with 44 kDa of relative molecular mass and had no isoforms (confirmed by zymography). It showed optimal activity at pH 9.0 and 30 °C temperature, while stability in the pH range 7.0–10.0 and temperature upto 50 °C. Organic solvents (hexane, acetone and methanol) as well as metal ions (Mg2+, Mn2+ and Na+) had stimulatory effects on lipase activity. Lipase immobilization was done using glutaraldehyde to form cross linked lipase enzyme aggregate (CLEA) which further enhanced its stability in the presence of methanol. Owing to its methanol tolerance property, it was employed heterogeneously for catalyzing transesterification of algal lipids in methanol. The qualitative efficacy of the FDS8 lipase in converting algal lipids into biodiesel was confirmed after analyzing the hexane extracted transesterification products by TLC and FTIR spectroscopy.

Effects of Radio Frequency Heating on the Stability and Antioxidant Properties of Rice Bran.

Radio frequency (RF) technology is considered as a rapid heating method. Lipase in rice bran could highly accelerate lipid oxidation. The objectives of this study were to establish the radio frequency heating conditions for lipase inactivation and to evaluate the stability and antioxidant capacity. The results showed that the suitable electrode gap for a 1 kg sample load was 6 cm, and it only took 2 min to heat rice bran from 25 °C to 100 °C. Besides, there were no significant differences in the total phenolic content, flavonoid content and color between the untreated and RF-treated group, and the DPPH free radical scavenging activity of the RF treatment reached 84.8%. The acid value, free fatty acid content and peroxide value of the RF-treated rice bran met the quality standard after 8 weeks of storage at 4, 25 and 37 °C. In summary, this study provides valuable information about the RF heating procedure, and shows the great potential of RF technology for stabilizing rice bran efficiently.

Kinetic and thermodynamic characterization of lipase from Aspergillus melleus and its biocatalytic performance for degradation of poly(ɛ‐caprolactone)

AbstractBACKGROUNDLipases are an interesting class of enzymes that can be used as biocatalysts for poly(ɛ‐caprolactone) degradation. This work reports on the biochemical characterization of a lipase produced through solid‐state fermentation by Aspergillus melleus and its application to degrade poly(ɛ‐caprolactone).RESULTSLipase demonstrated the best activity and remained stable even after 24 h at an optimal pH of 7.5 and 40 °C. The Km and Vmax values for p‐nitrophenyl palmitate hydrolysis derived from Lineweaver–Burk plot were 0.286 mmol L−1 and 142.86 μmol mL−1 min−1, respectively. Thermal inactivation studies revealed a half‐life of 1732.5 min (28.88 h) at 40 °C, and dramatically reduced at elevated temperatures. The activation energy for substrate hydrolysis was 28.81 kJ mol−1, whereas the entropy, enthalpy (ΔH°) and free energy (ΔG°) of thermal inactivation of lipase were determined to be 168.73 J mol−1 K−1, 160.60 and 107.79 kJ mol−1, respectively, at 40 °C. Increase in temperature showed a decline in ΔG°, but ∆H* remained constant. Incubation with organic solvents did not influence the enzyme stability; however, urea and guanidine hydrochloride reduced the lipase activity. Under optimal operating conditions, the enzyme presented excellent biocatalytic ability to poly(ɛ‐caprolactone) film degradation, leading to 53% weight loss. Characterization techniques, such as Fourier transform infrared, differential scanning calorimetry and scanning electron microscopy, corroborated the effective biodegradation of poly(ɛ‐caprolactone).CONCLUSIONIn conclusion, broad working pH, marked stability in the presence of organic solvents, and poly(ɛ‐caprolactone) degradation constitutes a lipase from A. melleus as a promising candidate for large‐scale bioremediation of solid waste.

Three Methods to Extract Membrane Glycerolipids: Comparing Sensitivity to Lipase Degradation and Yield.

Glycerolipids form the largest fraction of all membrane lipids and their composition changes quickly during plant development, the diurnal cycle, and in response to hormones and biotic or abiotic stress. A challenge to accurate glycerolipid measurement is that lipid-degrading enzymes tend to remain active during extraction, and special care must be taken to ensure their inactivation. Multiple extraction methods have arisen to cope with this challenge but only a few comparative studies are available in the literature. Here we compare three commonly used methods for lipase inactivation and lipid extraction from two different plant tissues. The first method employs formic acid in an organic solvent for inactivation followed by immediate separation of the organic phase, while the second uses the same acidic solvent, but expands the time of lipase inactivation and lipid extraction by incubation at low temperature. The third method includes a boiling step of the tissue in isopropanol for enzyme inactivation. The first method is the fastest for lab conditions with few samples, the second and third are convenient with large sample numbers, including field work. The first two methods are commonly followed by lipid derivatization and gas chromatography, while the third avoids acids and is thus preferable for lipidomics approaches. We directly compare the methods on both Arabidopsis thaliana and Sorghum bicolor leaf tissues and measure the relative abundances of glycerolipid species formed by lipase activity. We conclude that each method provides intact lipid extracts of similar quality, if performed according to the protocols described below.

Effect of roasting process on enzymes inactivation and starch properties of highland barley

Roasting may be beneficial to extend the shelf life by inactivating the lipases and peroxidases in highland barley, but it may lead to the deterioration of starch quality. In this study, the pre-treatment techniques of pearling and tempering were tried to improve the efficiency of inactivation, and different roasting treatment parameters were compared to obtain the optimum treatment conditions, under which thermally degraded starch may be less. Pearling had been proved to be an effective means in reducing enzyme content, and tempering could improve the sensitivity of enzymes to heat. Synergism of the two pre-treatment methods increased the inactivation of lipase and peroxidase in highland barley to 80% and 100%, respectively, and the optimal pre-treatment and roasting condition was P20M16T16 (20% pearling rate, 16% moisture, and 16 min treatment time) at 180 °C. Under this condition, the starch quality was basically consistent with those of control starch. For roasting treatment starch, the birefringence intensity, swelling power, and solubility slightly decreased and the polarized cross also still existed, while the relative crystallinity slightly increased and the crystal type unchanged. Roasting treatment starch showed higher pasting temperature and lower paste viscosity, and the increasing To, Tp, and the decreasing enthalpy.