Enzymatic Preparation, In-Depth Molecular Analysis, and In Vitro Digestion Simulation of Palmitoleic Acid (ω-7)-Enriched Fish Oil Triacylglycerols

In this study, an enzymatic reaction was developed for synthesizing pure triacylglycerols (TAG) with a high content of palmitoleic acid (POA) using fish byproduct oil. The characteristics of synthesized structural TAGs rich in POA (POA-TAG) were analyzed in detail through ultrahigh-performance liquid chromatography Q Exactive orbitrap mass spectrometry. Optimal conditions were thoroughly investigated and determined for reaction systems, including the use of Lipozyme TL IM and Novozym 435, 15 wt % lipase loading, substrate mass ratio of 1:3, and water content of 2.5 and 0.5 wt %, respectively, resulting in yields of 67.50 and 67.45% for POA-TAG, respectively. Multivariate statistical analysis revealed that TAG 16:1/16:1/20:4, TAG 16:1/16:1/16:1, TAG 16:1/16:1/18:1, and TAG 16:0/16:1/18:1 were the main variables in Lipozyme TL IM and Novozym 435 enzyme-catalyzed products under different water content conditions. Finally, the fate of POA-TAG across the gastrointestinal tract was simulated using an in vitro digestion model. The results showed that the maximum release of free fatty acids and apparent rate constants were 71.44% and 0.0347 s-1, respectively, for POA-TAG lipids, and the physical and structural characteristics during digestion depended on their microenvironments. These findings provide a theoretical basis for studying the rational design of POA-structural lipids and exploring the nutritional and functional benefits of POA products.

Advanced stimuli-responsive membranes for smart separation

Membranes have been extensively studied and applied in various fields owing to their high energy efficiency and small environmental impact. Further conferring membranes with stimuli responsiveness can allow them to dynamically tune their pore structure and/or surface properties for efficient separation performance. This review summarizes and discusses important developments and achievements in stimuli-responsive membranes. The most commonly utilized stimuli, including light, pH, temperature, ions, and electric and magnetic fields, are discussed in detail. Special attention is given to stimuli-responsive control of membrane pore structure (pore size and porosity/connectivity) and surface properties (wettability, surface topology, and surface charge), from the perspective of determining the appropriate membrane properties and microstructures. This review also focuses on strategies to prepare stimuli-responsive membranes, including blending, casting, polymerization, self-assembly, and electrospinning. Smart applications for separations are also reviewed as well as a discussion of remaining challenges and future prospects in this exciting field. This review offers critical insights for the membrane and broader materials science communities regarding the on-demand and dynamic control of membrane structures and properties. We hope that this review will inspire the design of novel stimuli-responsive membranes to promote sustainable development and make progress toward commercialization.

Separation of C18 Fatty Acid Esters and Fatty Acids Derived from Vegetable Oils Using Nanometer-Sized Covalent Organic Frameworks Incorporated in Polyepoxy Membranes

Fatty acids (FAs) and FA methyl esters (FAMEs) are easily isolated from vegetable oil and are important starting materials for the chemical industry to produce commercial products that are green, biorenewable, and nontoxic. A challenge in these applications is that mixtures of five or more FAs and FAMEs are isolated from a vegetable oil source, and methods to separate these mixtures are decades old and have increasingly high costs associated with the production of high-purity single-component FAs or FAMEs. We developed a method to separate these mixtures using mixed matrix membranes containing nanometer-sized covalent organic frameworks. The 2D, crystalline COFs possessed narrow distributions of pore sizes of 1.3, 1.8, 2.3, and 3.4 nm that separated FAs and FAMEs based on their degrees of unsaturation. The COFs were synthesized, characterized, and then encapsulated at 10 or 20% by weight into a prepolymer of epoxy that was then fully cured. For all mixed matrix membranes, as the degree of unsaturation increased, the FAs or FAMEs had a slower flux. The largest difference in flux was obtained for a COF/epoxy membrane with a pore size of 1.8 nm, and methyl stearate had a 5.9× faster flux than methyl linolenate. These are the first membranes that can separate the important C18 FAs and FAMEs found in vegetable oil.

Decreasing free fatty acid of crude palm oil with polyvinylidene fluoride hollow fiber membranes using a combination of chitosan and glutaraldehyde

Crude palm oil (CPO) has emerged as a significant commodity in the economic and social development of producer nations.