Immobilization of Lipase from Thermomyces Lanuginosus and Its Glycerolysis Ability in Diacylglycerol Preparation.

In the glycerolysis process for diacylglycerol (DAG) preparation, free lipases suffer from poor stability and the inability to be reused. To address this, a cost-effective immobilized lipase preparation was developed by cross-linking macroporous resin with poly (ethylene glycol) diglycidyl ether (PEGDGE) followed by lipase adsorption. The selected immobilization conditions were identified as pH 7.0, 35 °C, cross-linking agent concentration 2.0%, cross-linking time 4 h, lipase amount 5 mg/g of support, and adsorption time 4 h. Enzymatic properties of the immobilized lipase were analyzed, revealing enhanced pH stability, thermal stability, storage stability, and operational stability post-immobilization. The conditions for immobilized enzyme-catalyzed glycerolysis to produce DAG were selected, demonstrating the broad applicability of the immobilized lipase. The immobilized lipase catalyzed glycerolysis reactions using various oils as substrates, with DAG content in the products ranging between 35 and 45%, demonstrating broad applicability. Additionally, the changes during the repeated use of the immobilized lipase were characterized, showing that mechanical damage, lipase leakage, and alterations in the secondary structure of the lipase protein contributed to the decline in catalytic activity over time. These findings provide valuable insights for the industrial application of lipase.

Enzymatic preparation of diacylglycerols: lipase screening, immobilization, characterization and glycerolysis performance.

BACKGROUNDS: Glycerolysis, with its advantages of readily available raw materials, simple operation, and mild reaction conditions, is a primary method for producing diacylglycerol (DAG). However, enzymatic glycerolysis faces challenges such as high enzyme costs, low reuse efficiency, and poor stability. The study aims to develop a cost-effective immobilized enzyme by covalently binding lipase to pre-activated carriers through the selection of suitable lipases, carriers, and activating agents. The optimization is intended to improve the glycerolysis reaction for efficient DAG production. RESULTS: Lipase CN-TL (from Thermomyces lanuginosus) was selected through glycerolysis reaction and molecular docking to catalyze the glycerolysis reaction. Optimizing the immobilization method by covalently binding CN-TL to poly(ethylene glycol) diglycidyl ether (PEGDGE)-preactivated resin LX-201A resulted in the preparation of the immobilized enzyme TL-PEGDGE-LX. The immobilized enzyme retained over 90% of its initial activity after five consecutive reactions, demonstrating excellent reusability. The DAG content in the product remained at 84.8% of its initial level, further highlighting the enzyme's potential for reusability and its promising applications in the food and oil industries. CONCLUSIONS: The immobilized lipase TL-PEGDGE-LX, created by covalently immobilizing lipase CN-TL on PEGDGE-preactivated carriers, demonstrated broad applicability and excellent reusability. This approach offers an economical and convenient immobilization strategy for the enzymatic glycerolysis production of DAG. © 2024 Society of Chemical Industry.

Asterias Rolleston starfish gonad lipids: A novel source of Omega-3 fatty acids - assessment of major components and their antioxidant activities.

The major lipids and antioxidant activities of Asterias rolleston gonad lipids were evaluated systematically. Major lipids of A. Rolleston gonad lipids were triacylglycerols (TAGs) and phospholipids (PLs). Total lipids were composed of 15.62% of polyunsaturated fatty acids (PUFAs), and 40.81% of monounsaturated fatty acids (MUFAs). The most abundant PUFA were C20:5n-3 (EPA) (6.28%) and C22:6n-3 (DHA) (5.80%). Predominantly composed of phosphatidylcholine (PC) and phosphatidylethanolamine (PE), polar lipids were rich in PUFAs and could contain up to 34.59% EPA and DHA, and PE and PI (phosphatidylinositol) were also found to be the main carriers of EPA and ARA (arachidonic acid) in polar lipids. The MUFA and PUFA of Sn-2 in TAG are 39.72% and 30.37%, respectively. A total of 64 TAG species were identified, with Eo-P-M, Eo-Eo-M, and M-M-Eo being the main TAGs components. Moreover, A. rollestoni gonad lipids exhibited potent radical scavenging activities and reducing power in a dose-dependent manner.

Effect of diacylglycerol on partial coalescence of aerated emulsions: Fat crystal-membrane interaction and air-liquid Interface interaction insights.

Currently, the poor whipping capabilities of anhydrous milk fat (AMF) in aerated emulsion products are a major obstacle for their use in beverages like tea and coffee, as well as in cakes and desserts, presenting fresh hurdles for the food industry. In this study, the mechanism of action of diacylglycerols (DAGs) with different carbon chain lengths and degrees of saturation on the partial coalescence of aerated emulsions was systematically investigated from three fundamental perspectives: fat crystallization, air-liquid interface rheology, and fat globule interface properties. The optimized crystallization of long carbon chain length diacylglycerol (LCD) based on stearate enhances interactions between fat globules at the air-liquid interface (with an elastic modulus E' reaching 246.42 mN/m), leading to a significantly reduced interface membrane strength. This promotes fat crystal-membrane interactions during whipping, resulting in a thermally stable foam structure with excellent shaping capability due to enhanced partial coalescence of fat globules. Although Laurate based medium carbon chain length diacylglycerol (MCD) promoted fat crystallization and optimized interface properties, it showed weaker foam properties because it did not adequately encapsulate air bubbles during whipping. Conversely, oleate long carbon chain length diacylglycerol (OCD) proved to be ineffective in facilitating fat crystal-membrane interaction, causing foam to have a subpar appearance. Hence, drawing from the carefully examined fat crystal-membrane interaction findings, a proposed mechanism sheds light on how DAGs impact the whipping abilities of aerated emulsions. This mechanism serves as a blueprint for creating aerated emulsions with superior whipping capabilities and foam systems that are resistant to heat.

Effects of Silica Hydrogel on Degumming of Fragrant Rapeseed Oil.

Hot-pressed rapeseed oils with pleasant flavor, i.e., fragrant rapeseed oils, are favored by consumers, especially people from the southwest provinces of China. Although degumming is an important section in producing edible rapeseed oils, conventional degumming techniques are generally suffered from disadvantages such as moisture control, and large losses of micronutrients and flavors. In the present paper, hot-pressed rapeseed oils were treated with silica hydrogel to remove their gums, and changes in phospholipids, acid values, peroxide values, tocopherols, total phenols, and flavor compounds were analyzed to compare the silica hydrogel-degumming with conventional methods. The optimized conditions were suggested to be carried out at 45°C for 15 min, and the silica hydrogel dosage was 1.10%. More than 97.00% of phospholipids were removed after the degumming, and more than 85.00% of micronutrients, were retained in the treated oils. The degumming efficiency was therefore significantly higher than those operated by conventional acid degumming and soft degumming techniques. It was found that the dosage of the silica hydrogel significantly affected the removal rate of phospholipids compared with degumming time and temperature. There were nearly typical volatile compounds found in the rapeseed oils, while most of them kept almost stable after the silica hydrogel-degumming. In this regard, silica hydrogel adsorption exhibited little effect on volatile compounds, making it more suitable for the production of fragrant rapeseed oils.

Kinetics, Thermodynamics and Mechanism of Enzymatic Degradation of Zearalenone in Degummed Corn Oil.

The kinetics and thermodynamics of the enzymatic degradation of zearalenone (ZEN) in degummed corn oil were investigated by analyzing the impacts of temperature, pH, ZEN hydrolase dosage and ZEN concentration on the initial reaction rate. The kinetic study found that the maximum reaction rate was 0.97 µmol × kg−1 min−1, the Michaelis constant (Km) was 11,476 µmol × kg−1 and the Michaelis equation was V = 0.97[S]/(11,476 + [S]). The thermodynamic study showed that the activation energy (Ea) was 70.37 kJ·mol−1, the activation enthalpy change of the reaction (ΔH) > 0, the free energy of activation (ΔG) > 0 and the activation entropy change (ΔS) < 0, indicating the reaction could not be spontaneous. The reaction mechanism of ZEN was studied by a hybrid quadrupole orbitrap mass spectrometer. It was found that ZEN first generated the intermediate G/L/D/W-ZEN+H2O, followed by generating the intermediate W-ZEN-H2O under the action of a degrading enzyme. Then, the lactone bond was opened to produce C18H24O6, and finally the decarboxylation product C17H24O4 formed automatically.

Removal of Zearalenone from Degummed Corn Oil by Hydrolase on a Batch-Refining Unit.

The removal of zearalenone (ZEN) from degummed corn oil (DCO) using hydrolase on a batch-refining unit was studied. According to single-factor and response surface experiments, the optimum technological conditions for reaching the maximum degradation rate were a temperature of 39.01 °C, a pH of 8.08, a time of 3.9 h, and an enzyme dosage of 44.7 mg/kg, whereby the rate of ZEN degradation can reach 94.66%. Different effects on the removal of ZEN were observed at different initial ZEN contents under the optimal technological conditions, of which the decrease was rapid for high ZEN content and slow for low ZEN content.

Static stability of partially crystalline emulsions: Impacts of carrageenan and its blends with xanthan gum and/or guar gum.

In the present study, four different combinations of gums, including carrageenan (CG), its binary blends with xanthan gum (XG) or guar gum (GG) in equal ratios, and its ternary blends with XG and GG in three equal ratios, were involved into making partially crystalline emulsions (PCEs), respectively. The freshly prepared emulsions were systematically characterized by rheological property, particle size distribution, microscopic morphology, interfacial property, and intermolecular interactions, and their emulsion stabilities were further evaluated using multiple light scattering technique and storage test. All PCEs stabilized by gum blends (CG + XG, CG + GG, and CG + XG + GG) obtained decreased apparent viscosities at 0.01 s-1 (10.12-25.32 Pa·s), particle sizes (3.12-4.06 µm), as well as interfacial protein concentrations (22.60-27.01 mg/m2), which were much lower than those with single CG (35.98 Pa·s, 6.72 µm, and 47.74 mg/m2, respectively). The microscopic morphology showed that blending CG with XG and/or GG contributed to formation of firmer three-dimensional matrix, thereby preventing the aggregation of fat droplets. Inclusion of XG and/or GG also significantly reduced contribution of hydrophobic interactions from 0.72 to 0.24-0.44 mg/mL. Both multiple light scattering and storage test revealed that emulsion instabilities were mainly manifested as a clarification at the bottom and an agglomeration at the top. PCE-CG + XG + GG exhibited superior stability with low creaming index (6.20 %) and viscosity (1180.0 mPa·s) after three months of storage. The research aims to evaluate the effects of CG and its blends with XG and GG on stability of PCEs, and the results potentially provide valuable information for manufacture of stable PCE foods.