Simplified Enzymatic Upgrading of High-Acid Rice Bran Oil Using Ethanol as a Novel Acyl Acceptor

Lipidomics analysis of rice bran during storage unveils mechanisms behind dynamic changes in functional lipid molecular species

Rice bran, recognized for its rich lipids and health-beneficial bioactive compounds, holds considerable promise in applications such as rice bran oil production. However, its susceptibility to lipid hydrolysis and oxidation during storage presents a significant challenge. In response, we conducted an in-depth metabolic profiling of rice bran over a storage period of 14 days. We focused on the identification of bioactive compounds and functional lipid species (25 acylglycerols and 53 phospholipids), closely tracking their dynamic changes over time. Our findings revealed significant reductions in these lipid molecular species, highlighting the impact of rancidity processes. Furthermore, we identified 19 characteristic lipid markers and elucidated that phospholipid and glycerolipid metabolism were key metabolic pathways involved. By shedding light on the mechanisms driving lipid degradation in stored rice bran, our study significantly advanced the understanding of lipid stability. These information provided valuable insights for countering rancidity and optimizing rice bran preservation strategies.

Streamlined enzymatic synthesis of human milk fat substitutes

The positional distribution of palmitic acid (PA) in human milk fat substitutes (HMFSs) plays a pivotal role in mimicking the nutritional profile of human milk fat for nourishing non-breastfed infants. This study innovatively introduced a streamlined enzymatic process for preparing HMFSs rich in sn-2 PA using palm stearin, a PA-rich source without the necessity for positional distribution of PA. The initial step involved enhancing the sn-2 PA concentration through enzymatic interesterification using Lipase UM1, which exhibited superior catalytic efficiency than Novozym 435. This process increased the sn-2 PA level from 40.98 % to 64.51 %. Subsequently, acidolysis was employed to reduce PA levels by replacing PA at sn-1,3 positions using sn-1,3-regioselective lipases. The PA content decreased from 60.64 % to 26.73 %, simultaneously raising the relative sn-2 PA concentration to 71.57 %, meeting the benchmarks for HMFSs. This study establishes a robust conceptual framework for the prospective industrial synthesis of HMFSs.

Synthesis of lipase-hydrogel microspheres and their application in deacidification of high-acid rice bran oil

The main challenge of rice bran oil (RBO) as a highly nutritional edible oil is the high content of free fatty acids.

Current State and Perspectives on Transesterification of Triglycerides for Biodiesel Production

Triglycerides are the main constituents of lipids, which are the fatty acids of glycerol. Natural organic triglycerides (viz. virgin vegetable oils, recycled cooking oils, and animal fats) are the main sources for biodiesel production. Biodiesel (mono alkyl esters) is the most attractive alternative fuel to diesel, with numerous environmental advantages over petroleum-based fuel. The most practicable method for converting triglycerides to biodiesel with viscosities comparable to diesel fuel is transesterification. Previous research has proven that biodiesel–diesel blends can operate the compression ignition engine without the need for significant modifications. However, the commercialization of biodiesel is still limited due to the high cost of production. In this sense, the transesterification route is a crucial factor in determining the total cost of biodiesel production. Homogenous base-catalyzed transesterification, industrially, is the conventional method to produce biodiesel. However, this method suffers from limitations both environmentally and economically. Although there are review articles on transesterification, most of them focus on a specific type of transesterification process and hence do not provide a comprehensive picture. This paper reviews the latest progress in research on all facets of transesterification technology from reports published by highly-rated scientific journals in the last two decades. The review focuses on the suggested modifications to the conventional method and the most promising innovative technologies. The potentiality of each technology to produce biodiesel from low-quality feedstock is also discussed.

Industrial biotransformations catalyzed by microbial lipases: screening platform and commercial aspects

The successfulness of a lipase-catalyzed industrial process depends on a proper lipase selection. In this work, an alternative screening platform for industrially important biotransformations catalyzed by microbial lipases was proposed. Thus, the reactivity of sixty lipase activities from spore-forming microorganisms towards hydrolytic and transesterification reactions by using p-nitrophenyl palmitate as a chromogenic acyl donor substrate was explored. Only three biocatalysts were capable of catalyzing all reactions tested. Fourteen biocatalysts did not show hydrolytic activity at all; however, they displayed transesterification activities using ethanol, starch, low-methoxyl (LM) pectin, high-methoxyl (HM) pectin, or vitamin C as acyl acceptors. Using heat-treated biocatalysts, hydrolytic activities were not highly correlated with the corresponding transesterification activities using ethanol (r =  -0.058, p = 0.660), starch (r = 0.431, p = 0.001), LM pectin (r =  -0.010, p = 0.938), HM pectin (r = 0.167, p = 0.202), and vitamin C (r =  -0.048, p = 0.716) as acyl acceptor. In addition, to the best of our knowledge, several transesterification activities produced from microorganisms of the genus Bacillus, Brevibacillus, Lysinibacillus, Geobacillus, or Sporosarcina were reported for first time. Finally, the global lipase market was presented and segmented by date, application, geography and player highlighting the commercial contribution of microbial lipases.

Integrated Utilization Strategy for Soybean Oil Deodorizer Distillate: Synergically Synthesizing Biodiesel and Recovering Bioactive Compounds by a Combined Enzymatic Process and Molecular Distillation

Soybean oil deodorizer distillate (SODD) is well recognized as a good source of both biodiesel and high-value bioactive compounds of tocopherols, squalene, and phytosterols. To achieve a one-step synthesis of biodiesel and recovery of bioactive compounds from SODD, four commercial immobilized enzymes (Novozym 435, Lipozyme TLIM, Lipozyme RMIM, and Lipozyme RM) and one self-prepared immobilized lipase MAS1-H108A were compared. The results showed that immobilized lipase MAS1-H108A due to the better methanol tolerance and higher catalytic activity gave the highest biodiesel yield of 97.08% under the optimized conditions: molar ratio of 1:2 (oil/methanol), temperature of 35 °C, and enzyme loading of 35 U/g SODD, even after 10 persistent cycles without significant decrease of activity. Simultaneously, there was no loss of tocopherols and squalene in SODD during the enzymatic reaction. Pure biodiesel (characterized by fourier transform infrared (FT-IR) and nuclear magnetic resonance (NMR)) and a high concentration of bioactive compounds could be successfully separated by molecular distillation at 100 °C. In a word, this work provides an interesting idea to achieve environmentally friendly treatment of SODD by combining an enzymatic process and molecular distillation, and it is suitable for industrial production.

Immobilization of Aspergillus niger lipase onto a novel macroporous acrylic resin: Stable and recyclable biocatalysis for deacidification of high-acid soy sauce residue oil

Deacidification of high-acid soy sauce residue (SSR) oil is crucial to utilization of SSR oil. Aspergillus niger lipase (ANL) has been widely applied for such purpose while its immobilization still has large room for improvement. ANL was immobilized onto six different macroporous acrylic resins, accounting the effect of the different textural properties of resins on stability and their potential for application in enzymatic deacidification. The resin MARE with lower porosity, higher bulk density, and medium hydrophobicity, was chosen as the best carrier for the best thermostability and reusability. ANL-MARE is a promising catalyst than Novozym 40086, which not only exhibited higher deacidification activity and good thermostability, but also was continuously reused for 15 cycles and efficiently catalyzed from high-acid SSR oil into diacylglycerol-enriched oil. Therefore, immobilized ANL was a novel, low-cost and recyclable biocatalyst that could be used as a good alternative to higher-cost commercial lipases in industrial applications.

Highly Efficient and Enzyme-Recoverable Method for Enzymatic Concentrating Omega-3 Fatty Acids Generated by Hydrolysis of Fish Oil in a Substrate-Constituted Three-Liquid-Phase System

A novel three-liquid-phase system which contained fish oil as the nonpolar phase was developed for the lipase-based hydrolysis of fish oil and subsequent enrichment of the omega-3 polyunsaturated fatty acids (n-3 PUFA) in the glyceride fraction of the fish oil. In comparison with the traditional oil/water system, the enrichment factor of n-3 PUFA in this system was increased by 363.4% as a result of a higher dispersity, higher selectivity of the lipase for the other fatty acids except for n-3PUFA, and relief of product inhibition. The content of n-3 PUFA in the glyceride fraction could be concentrated to 67.97% by repeated hydrolysis after removing the free fatty acids. Furthermore, the lipase could be reused for at least eight rounds. This method would be an ideal approach for enriching n-3 PUFA because it is cost-effective, low in toxicity, and easily scaled up.

A Thermostable Monoacylglycerol Lipase from Marine Geobacillus sp. 12AMOR1: Biochemical Characterization and Mutagenesis Study

Lipases with unique substrate specificity are highly desired in biotechnological applications. In this study, a putative marine Geobacillus sp. monoacylglycerol lipase (GMGL) encoded gene was identified by a genomic mining strategy. The gene was expressed in Escherichia coli as a His-tag fusion protein and purified by affinity chromatography with a yield of 264 mg per liter fermentation broth. The recombinant GMGL shows the highest hydrolysis activity at 60 °C and pH 8.0, and the half-life was 60 min at 70 °C. The GMGL is active on monoacylglycerol (MAG) substrate but not diacylglycerol (DAG) or triacylglycerol (TAG), and produces MAG as the single product in the esterification reaction. Modeling structure analysis showed that the catalytic triad is formed by Ser97, Asp196 and His226, and the flexible cap region is constituted by residues from Ala120 to Thr160. A mutagenesis study on Leu142, Ile145 and Ile170 located in the substrate binding tunnel revealed that these residues were related with its substrate specificity. The k_cat/K_m value toward the pNP-C6 substrate in mutants Leu142Ala, Ile145Ala and Ile170Phe increased to 2.3-, 1.4- and 2.2-fold as compared to that of the wild type, respectively.