Enzymatic synthesis of oligo- and polysaccharide fatty acid esters

Development of a rapid quantitative method of analysis of carbohydrate fatty acid ester reaction mixtures using 1H qNMR

Two new analytical methods, applying absolute 1H qNMR, were developed to monitor product yield and quantify unreacted carbohydrate and fatty acid reactants, in the synthesis of carbohydrate fatty acid esters (CFAE). These methods provide a mass balance of the crude reaction mixtures and diversify the analytical screening and quantitation approaches available within the synthesis of these molecules. Both methods were validated for the model reaction of methyl α-d-glucopyranoside (MAG) and lauric acid (LA) to form the mono ester product, methyl 6-O-dodecanoyl-α-d-glucopyranoside. Analysis in CD3OD by 1H qNMR, with fumaric acid (FA) as an internal standard (IS), allowed monitoring of all reaction components. Alternatively, using CDCl3 and (E)-stilbene as IS enabled the analysis of CFAE and fatty acid. Parameters calculated for method validation included specificity and selectivity, linearity, accuracy, intermediate precision, limit of detection (LOD), limit of quantification (LOQ) and robustness. Both methods provided excellent linearity with R2 > 0.997. The accuracy, precision, and robustness of the method in CD3OD was <2 % uncertainty making it suitable for complete reaction analysis. The method completed in CDCl3 resulted in accuracy, intermediate precision, and robustness of <5 %, except for accuracy in the lowest levels of concentration (>5 %). For all related analytes in the CD3OD and CDCl3 methods, the LOD and LOQ were determined to ensure applicability for the intended use in the assessment of reaction crude composition. Finally, the system suitability was assessed in a scaled lipase catalysed CFAE synthetic reaction. The determined qNMR product yields were verified against isolated purified product yields with <5 % uncertainty.

Enzyme-catalyzed transesterification of galactomannan extracted from mesquite seed (Prosopis velutina) with vinyl carboxylate esters

Galactomannans (GM) are hemicellulosic polysaccharides composed of D-mannopyranose chains linked by β (1 → 4) glycosidic linkages with branches of D-galactopyranose linked by α (1 → 6) linkages. This polysaccharide is recognized for its hydrophilic character, as it is rich in hydroxyl groups (-OH). This chemical characteristic, combined with the absence of ionic charges, enables structural modifications such as transesterification of the fatty acid chains (FA), which provides a strategy for obtaining amphiphilic structures. The enzyme-catalyzed syntheses were carried out in DMSO with GM decanoate (GMD) and GM palmitate (GMP) at different molar ratios (0.5 and 1.0) and the resulting structures were evaluated with infrared spectroscopy (FTIR), solid-state nuclear magnetic resonance (CP/MAS 13C NMR) and differential scanning calorimetry (DSC). The FTIR spectrum confirmed the transesterification of GM with the appearance of a C[bond, double bond]O band (1730-1750 cm-1). These results were confirmed by the signals observed at 177 and 30 ppm in the CP/MAS 13C NMR spectrum, which corresponded to the C[bond, double bond]O groups of the esters and the terminal -CH3 groups of the FA chains, respectively. Finally, DSC showed glass transition temperatures (Tg) in the range 43-51 °C, while the melting temperatures (Tm) of the GM esters (59 °C) were not affected by different degrees of esterification (DE) for GMD (0.37 and 0.71) and GMP (0.47 and 0.57).

Functionalization Methods of Starch and Its Derivatives: From Old Limitations to New Possibilities

It has long been known that starch as a raw material is of strategic importance for meeting primarily the nutritional needs of people around the world. Year by year, the demand not only for traditional but also for functional food based on starch and its derivatives is growing. Problems with the availability of petrochemical raw materials, as well as environmental problems with the recycling of post-production waste, make non-food industries also increasingly interested in this biopolymer. Its supporters will point out countless advantages such as wide availability, renewability, and biodegradability. Opponents, in turn, will argue that they will not balance the problems with its processing and storage and poor functional properties. Hence, the race to find new methods to improve starch properties towards multifunctionality is still ongoing. For these reasons, in the presented review, referring to the structure and physicochemical properties of starch, attempts were made to highlight not only the current limitations in its processing but also new possibilities. Attention was paid to progress in the non-selective and selective functionalization of starch to obtain materials with the greatest application potential in the food (resistant starch, dextrins, and maltodextrins) and/or in the non-food industries (hydrophobic and oxidized starch).

Trends in "green" and novel methods of pectin modification - A review

Modification of hydrocolloids to alter their functional properties using chemical methods is well documented in the literature. There has been a recent trend of adopting eco-friendly and "green" methods for modification. Pectin, being a very important hydrocolloid finds its use in various food applications due to its gelling, emulsifying, and stabilizing properties. The adoption of various "green" methods can alter the properties of pectin and make it more suitable for incorporation in food products. The novel approaches such as microwave and pulsed electric field can also be utilized for solvent-free modification, making it desirable from the perspective of sustainability, as it reduces the consumption of organic chemicals. Pectic oligosaccharides (POSs) produced via novel approaches are being explored for their biological properties and incorporation in various functional foods. The review can help to set the perspective of potential scale-up and adoption by the food industry for modification of pectin.

Formation of Amphiphilic Molecules from the Most Common Marine Polysaccharides, toward a Sustainable Alternative?

Marine polysaccharides are part of the huge seaweeds resources and present many applications for several industries. In order to widen their potential as additives or bioactive compounds, some structural modifications have been studied. Among them, simple hydrophobization reactions have been developed in order to yield to grafted polysaccharides bearing acyl-, aryl-, alkyl-, and alkenyl-groups or fatty acid chains. The resulting polymers are able to present modified physicochemical and/or biological properties of interest in the current pharmaceutical, cosmetics, or food fields. This review covers the chemical structures of the main marine polysaccharides, and then focuses on their structural modifications, and especially on hydrophobization reactions mainly esterification, acylation, alkylation, amidation, or even cross-linking reaction on native hydroxyl-, amine, or carboxylic acid functions. Finally, the question of the necessary requirement for more sustainable processes around these structural modulations of marine polysaccharides is addressed, considering the development of greener technologies applied to traditional polysaccharides.

A novel maltoheptaose-based sugar ester having excellent emulsifying properties and optimization of its lipase-catalyzed synthesis

A novel maltoheptaose-palmitate ester (G7-PA) was synthesized and investigated for emulsion properties. First of all, the optimal conditions for lipase-catalyzed G7-PA synthesis, which were 0.2 of the G7/PA molar ratio, 33.5 U of immobilized CALB per 1 g of PA in 10% DMSO, were determined by response surface methodology. G7-PA was compared with the commercial sucrose-PA (S-PA) in terms of emulsion-forming ability and stability at extreme conditions. At the 0.1% surfactant concentration, G7-PA emulsion exhibited a droplet distribution similar to the 0.2% surfactant condition, while S-PA emulsion was quickly destabilized. G7-PA showed better emulsifying properties than the S-PA at the acidic condition (pH 3). Flocculation and phase separation was observed at the S-PA emulsion, but the G7-PA emulsion was stable for 7-day. In thermostability tests, G7-PA and S-PA both were stable up to the boiling temperature. Conclusively, G7-PA exhibits excellent properties as a biosurfactant in O/W emulsion compared with S-PA.

Lipase-Catalyzed Regioselective Synthesis of Dextrin Esters

Four lipase enzymes were investigated as catalysts in the synthesis of regioselectively monosubstituted dextrin esters from dextrin and vinyl acetate. An immobilized lipase enzyme (Lipozyme TL IM) exhibited the highest activity. This enzyme showed regioselective substitution of the dextrin at the primary hydroxyl group (C6 position) under optimal conditions (60 °C for 24 h, using a 1:3 molar ratio of glucose unit/vinyl acetate and 2.5 U/mL enzyme dosage in an organic solvent). To compare the reactivity of other vinyl esters, monosubstituted dextrin esters (degrees of substitution [DS] ≈ 1) with varying side-chain lengths (C2-C12) were synthesized. With increasing side-chain length, the initial catalytic activity of the lipase enzyme decreased, resulting in lower DS values. However, the final DS values of the monosubstituted dextrin esters with longer side chains were higher than those of the shorter-chain analogues, because of an increase in affinity between the substrate and acyl donor.

Analysis of carbohydrates and glycoconjugates by matrix-assisted laser desorption/ionization mass spectrometry: An update for 2013-2014

This review is the eighth update of the original article published in 1999 on the application of Matrix-assisted laser desorption/ionization mass spectrometry (MALDI) mass spectrometry to the analysis of carbohydrates and glycoconjugates and brings coverage of the literature to the end of 2014. Topics covered in the first part of the review include general aspects such as theory of the MALDI process, matrices, derivatization, MALDI imaging, fragmentation, and arrays. The second part of the review is devoted to applications to various structural types such as oligo- and poly- saccharides, glycoproteins, glycolipids, glycosides, and biopharmaceuticals. Much of this material is presented in tabular form. The third part of the review covers medical and industrial applications of the technique, studies of enzyme reactions, and applications to chemical synthesis. © 2018 Wiley Periodicals, Inc. Mass Spec Rev 37:353-491, 2018.

Enzymatic synthesis of isomaltotriose palmitate and evaluation of its emulsifying property

Enzymatic syntheses of oligosaccharide fatty acid esters are important owing to their wide range of industrial applications in the food, cosmetic, and pharmaceutical industries. Transesterification of isomaltotriose and palmitic acid vinyl ester, catalyzed by the metalloprotease thermolysin, was performed in organic solvents. The process parameters (reaction time and temperature) were optimized to achieve the highest yield of isomaltotriose palmitate (IP). The water content of the reaction system played a key role in the acylation of isomaltotriose. Dimethyl sulfoxide was thought to be the most suitable reaction medium by taking the degree of substitution of the modified isomaltotriose into account. The optimum reaction time, temperature, water content, and enzyme concentration were 24h, 45°C, 40%, and 0.05%, respectively, under which the product yield was as high as 89.7%. The enzyme operational stability study showed that thermolysin retained 51.5% of its initial activity for the synthesis of IP (even after repeated use for 72h). Moreover, test results showed that the emulsifying capacity and emulsion stability of IP are 107.5mL oil/g ester and 16.3%, respectively.

Synthesis and characterization of fatty acid oat β-glucan ester and its structure-curcumin loading capacity relationship

An amphiphilic fatty acid oat β-glucan ester (FAOGE) was first synthesized, and its structure-curcumin loading capacity (CLC) relationship was investigated. The DS of product increased with the addition of acyl imidazole, decreased with Mw of β-glucan, and did not relate to the acyl chain length. Characterizations by FT-IR and (1)H NMR evidenced the presence of ester groups in FAOGE and confirmed its successful synthesis. The aqueous self-aggregation behavior of FAOGE was revealed by transmission electron microcopy and dynamic light scattering. With the aid of response surface methodology, a quadratic polynomial equation was obtained to quantitatively describe the structure-CLC relationship of FAOGE by using Mw of β-glucan, acyl chain length, and DS as variables. The CLC increased with Mw of β-glucan and acyl chain length but maximized at a medium DS. The maximum CLC value was obtained as 4.05 μg/mg. Hence, FAOGE is a potential candidate in solubilizing and delivering hydrophobic food ingredients.

Magnetic biocatalysts and their uses to obtain biodiesel and biosurfactants

Nanobiocatalysis, as the synergistic combination of nanotechnology and biocatalysis, is rapidly emerging as a new frontier of biotechnology. The use of immobilized enzymes in industrial applications often presents advantages over their soluble counterparts, mainly in view of stability, reusability and simpler operational processing. Because of their singular properties, such as biocompatibility, large and modifiable surface and easy recovery, iron oxide magnetic nanoparticles (MNPs) are attractive super-paramagnetic materials that serve as a support for enzyme immobilization and facilitate separations by applying an external magnetic field. Cross-linked enzyme aggregates (CLEAs) have several benefits in the context of industrial applications since they can be cheaply and easily prepared from unpurified enzyme extracts and show improved storage and operational stability against denaturation by heat and organic solvents. In this work, by using the aforementioned advantages of MNPs of magnetite and CLEAs, we prepared two robust magnetically-separable types of nanobiocatalysts by binding either soluble enzyme onto the surface of MNPs functionalized with amino groups or by cross-linking aggregates of enzyme among them and to MNPs to obtain magnetic CLEAs. For this purpose the lipase B of Candida antarctica (CALB) was used. The hydrolytic and biosynthetic activities of the resulting magnetic nanobiocatalysts were assessed in aqueous and organic media. Thus, the hydrolysis of triglycerides and the transesterification reactions to synthesize biodiesel and biosurfactants were studied using magnetic CLEAs of CALB. The efficiency and easy performance of this magnetic biocatalysis validates this proof of concept and sets the basis for the application of magnetic CLEAs at industrial scale.

The effect of diesters and lauric acid on rheological properties of air/water interfaces stabilized by oligofructose lauric acid monoesters

In this study, the rheological properties of interfaces stabilized by oligofructose fatty acid esters were elucidated. First, the properties of interfaces stabilized by monoesters (ME), diesters (DE), lauric acid (LA), oligofructose (OF), and mixtures of ME with DE, LA, or OF were studied. Second, the properties of interfaces stabilized by the crude product (CP) containing ME, DE, LA, and OF were studied. The dependency of the dilatational modulus on frequency and deformation amplitude indicated the possible formation of a soft glass phase for ME, and a viscous interface for DE. When ME and DE were mixed at a ratio of 0.8/0.2, the experimental results suggest that the interfacial structure consists of islands of a glass phase formed by ME, dispersed in a 2D viscous phase of DE. CP stabilized interfaces, where the ratio ME/DE was higher, lead to a different rheological response. The ratio ME/DE plays an important role in the surface properties of the CP. This may have significant consequences for applications in macroscopic systems such as foams.