Lipase-catalyzed hydrolysis of fish oil in an optimum emulsion system

Preparation of functional oils rich in phytosterol esters and diacylglycerols by enzymatic transesterification

Phytosterol esters (PEs) and diacylglycerols (DAGs) have various health benefits in humans. In this study, PEs and DAGs were synthesized by lipase-catalyzed transesterification between a natural oil and phytosterols. First, commercial lipases were screened for transesterification and were further verified using multiple-ligand molecular docking. AYS "Amano" (a lipase from Candida rugosa) was found to be the optimum lipase. Subsequently, the enzymatic transesterification conditions were optimized. The optimized conditions were determined to be a 1:2 M ratio of phytosterols to oil, 100 mmol/L phytosterols, and 9 % AYS "Amano", and 50 °C for 24 h in 20 mL n-hexane. Under these conditions, over 70 % of phytosterols were converted to PEs. In this study, an efficient enzymatic process was developed to produce value-added functional oils rich in PEs and DAGs, with PEs content ≥ 31.6 %, DAGs content ≥ 11.2 %, acid value ≤ 0.91 mg KOH/g, and peroxide value ≤ 2.38 mmol/kg.

Lipase Catalyzed Transesterification of Model Long-Chain Molecules in Double-Shell Cellulose-Coated Oil-in-Water Emulsion Particles as Microbioreactors

Lipase-catalyzed transesterification is prevalent in industrial production and is an effective alternative to chemical catalysis. However, due to lipases’ unique structure, the reaction requires a biphasic system, which suffers from a low reaction efficiency caused by a limited interfacial area. The use of emulsion particles was found to be an effective way to increase the surface area and activity. This research focuses on cellulose as a natural surfactant for oil-in-water emulsions and evaluates the ability of lipase, introduced into the emulsion’s aqueous phase, to integrate with the emulsion microparticles and catalyze the transesterification reaction of high molecular weight esters dissolved in the particles’ cores. Cellulose-coated emulsion particles’ morphology was investigated by light, fluorescence and cryogenic scanning electron microscopy, which reveal the complex emulsion structure. Lipase activity was evaluated by measuring the hydrolysis of emulsified p-nitrophenyl dodecanoate and by the transesterification of emulsified methyl laurate and oleyl alcohol dissolved in decane. Both experiments demonstrated that lipase introduced in the aqueous medium can penetrate the emulsion particles, localize at the inner oil core interface and perform effective catalysis. Furthermore, in this system, lipase successfully catalyzed a transesterification reaction rather than hydrolysis, despite the dominant presence of water.

Progress in enrichment of n-3 polyunsaturated fatty acid: a review

n-3 Polyunsaturated fatty acids (n-3 PUFA) has been widely used in foods, and pharmaceutical products due to its beneficial effects. The content of n-3 PUFA in natural oils is usually low, which decreases its added value. Thus, there is an increasing demand on the market for n-3 PUFA concentrates. This review firstly introduces the differences in bioavailability and oxidative stability between different types of PUFA concentrate (free fatty acid, ethyl ester and acylglycerol), and then provides a comprehensive discussion of different methods for enrichment of lipids with n-3 PUFA including physical-chemical methods and enzymatic methods. Lipases used for catalyzing esterification, transesterification and hydrolysis reactions play an important role in the production of highly enriched various types of n-3 PUFA concentrates. Lipase-catalyzed alcoholysis or hydrolysis reactions are the mostly employed method to prepare high-quality n-3 PUFA of structural acylglycerols. Although many important advantages offered by lipases in enrichment of n-3 PUFA, the high cost of enzyme limits its industrial-scale production. Further research should focus on looking for biological enzymes with extraordinary catalytic ability and clear selectivity. Other novel technologies such as protein engineering and immobilization may be needed to modify lipases to improve its selectivity, catalytic ability and reuse.

Enzymatic enrichment of n-3 polyunsaturated fatty acid glycerides by selective hydrolysis

Most natural oils are low in n-3 polyunsaturated fatty acids (n-3 PUFAs) content, which limits their application in health products. In this study, n-3 PUFAs in glyceride form were selectively enriched by lipase-mediated hydrolysis of n-3 PUFA-containing oils. First, commercial lipases were screened, and the lipase AY "Amano" 400SD from Candida cylindracea was the best choice in producing n-3 PUFA glycerides from tuna oil. Subsequently, the hydrolysis conditions were optimized. Under the optimal conditions, the highest n-3 PUFA content in the glyceride fraction was found to be 57.7% after enzymatic hydrolysis. Addition of Ca²⁺ to the system significantly shortened the reaction time from 10 to 4 h. When algal oil was used as substrate, total PUFA contents in the glyceride fraction were 89.9%. This study provides an efficient enzymatic process to produce n-3 PUFA-enriched glyceride concentrates and demonstrates that AY "Amano" 400SD can effectively discriminate against n-3 PUFAs during hydrolysis.

Immobilization of Moniliella spathulata R25L270 Lipase on Ionic, Hydrophobic and Covalent Supports: Functional Properties and Hydrolysis of Sardine Oil

The oleaginous yeast Moniliella spathulata R25L270 was the first yeast able to grow and produce extracellular lipase using Macaúba (Acrocomia aculeate) cake as substrate. The novel lipase was recently identified, and presented promising features for biotechnological applications. The M. spathulata R25L270 lipase efficiently hydrolyzed vegetable and animal oils, and showed selectivity for generating cis-5,8,11,15,17-eicosapentaenoic acid from sardine oil. The enzyme can act in a wide range of temperatures (25–48 °C) and pH (6.5–8.4). The present study deals with the immobilization of M. spathulata R25L270 lipase on hydrophobic, covalent and ionic supports to select the most active biocatalyst capable to obtain omega-3 fatty acids (PUFA) from sardine oil. Nine immobilized agarose derivatives were prepared and biochemically characterized for thermostability, pH stability and catalytic properties (K_M and V_max). Ionic supports improved the enzyme–substrate affinity; however, it was not an effective strategy to increase the M. spathulata R25L270 lipase stability against pH and temperature. Covalent support resulted in a biocatalyst with decreased activity, but high thermostability. The enzyme was most stabilized when immobilized on hydrophobic supports, especially Octyl-Sepharose. Compared with the free enzyme, the half-life of the Octyl-Sepharose derivative at 60 °C increased 10-fold, and lipase stability under acidic conditions was achieved. The Octyl-Sepharose derivative was selected to obtain omega-3 fatty acids from sardine oil, and the maximal enzyme selectivity was achieved at pH 5.0.