Comparison of the Esterification of Fructose and Palmitic Acid in Organic Solvent and in Supercritical Carbon Dioxide

Esters in the Food and Cosmetic Industries: An Overview of the Reactors Used in Their Biocatalytic Synthesis

Esters are versatile compounds with a wide range of applications in various industries due to their unique properties and pleasant aromas. Conventionally, the manufacture of these compounds has relied on the chemical route. Nevertheless, this technique employs high temperatures and inorganic catalysts, resulting in undesired additional steps to purify the final product by removing solvent residues, which decreases environmental sustainability and energy efficiency. In accordance with the principles of "Green Chemistry" and the search for more environmentally friendly methods, a new alternative, the enzymatic route, has been introduced. This technique uses low temperatures and does not require the use of solvents, resulting in more environmentally friendly final products. Despite the large number of studies published on the biocatalytic synthesis of esters, little attention has been paid to the reactors used for it. Therefore, it is convenient to gather the scattered information regarding the type of reactor employed in these synthesis reactions, considering the industrial field in which the process is carried out. A comparison between the performance of the different reactor configurations will allow us to draw the appropriate conclusions regarding their suitability for each specific industrial application. This review addresses, for the first time, the above aspects, which will undoubtedly help with the correct industrial implementation of these processes.

Coupling of Bioreaction and Separation via Novel Thermosensitive Ionic Liquids Applied in the Baker's Yeast-Catalyzed Reduction of Ethyl 2-oxo-4-phenylbutyrate

The use of baker's yeast to reduce ethyl 2-oxo-4-phenylbutyrate (EOPB) in conventional biphasic systems is hindered by low productivities due to mass transfer resistance between the biocatalyst and the substrate partitioned into two different phases. To overcome the limitation, a new reaction-separation coupling process (RSCP) was configured in this study, based on the novel thermosensitive ionic liquids (ILs) with polyoxyethylene-tail. The solubility of ILs in common solvents was investigated to configure the unique thermosensitive ionic liquids-solvent biphasic system (TIBS) in which the reduction was performed. [(CH₃)₂N(C₂H₅)(CH₂CH₂O)₂H][PF₆] (c₂) in 1,2-dimethoxyethane possesses the thermosensitive function of homogeneous at lower temperatures and phase separating at higher temperatures. The phase transformation temperature (PTT) of the mixed system of c₂/1,2-dimethoxyethane (v/v, 5:18) was about 33 °C. The bioreaction takes place in a "homogeneous" liquid phase at 30 °C. At the end of each reduction run, the system temperature is increased upon to the PTT, while c₂ is separated from 1,2-dimethoxyethane with turning the system into two phases. The enantiomeric excesses (e.e.) of ethyl (R)-2-hydroxy-4-phenylbutyrate ((R)-EHPB) increased about 25~30% and the yield of ethyl-2-hydroxy-4-phenylbutyrate (EHPB) increased 35% in TIBS, compared with the reduction in 1,2-dimethoxyethane. It is expected that the TIBS established in this study could provide many future opportunities in the biocatalysis.

Green Technologies for the Production of Modified Lipids

In recent years, the use of green solvents in enzyme catalysis of lipophilic compounds is achieving increasing interest from different perspectives. Conducting reactions under supercritical fluids, ionic liquids, deep eutectic solvents, and other green solvents affords opportunities to overcome problems associated with the lack of solubility of lipids in conventional solvents and the poor miscibility of substrates. Research on the biocatalytic production of modified lipids in the framework of green chemistry is conducted to improve the efficiency of obtaining the desired products as well as the selectivity, stability, and activity of the enzymatic systems. This overview describes the fundamentals and characteristics of several types of green solvents, the main variables involved in enzymatic processes, and examples and applications in the field of lipid modification.

Sugar ester surfactants: enzymatic synthesis and applications in food industry

Sugar esters are non-ionic surfactants that can be synthesized in a single enzymatic reaction step using lipases. The stability and efficiency of lipases under unusual conditions and using non-conventional media can be significantly improved through immobilization and protein engineering. Also, the development of de novo enzymes has seen a significant increase lately under the scope of the new field of synthetic biology. Depending on the esterification degree and the nature of fatty acid and/or sugar, a range of sugar esters can be synthesized. Due to their surface activity and emulsifying capacity, sugar esters are promising for applications in food industry.

In vitro antibacterial activities and mechanism of sugar fatty acid esters against five food-related bacteria

The objective of this study was to evaluate the antibacterial activities of sugar fatty acid esters, with different fatty acid and saccharide moieties, against five food-related bacteria including Bacillus cereus, Bacillus subtilis, Staphylococcus aureus, Escherichia coli and Salmonella typhimurium. Sucrose monocaprate showed the strongest antibacterial activity against all tested bacteria, especially Gram-positive bacteria. The minimum inhibitory concentrations (MICs) for Gram-positive bacteria and Gram-negative bacteria were 2.5 and 10 mM, respectively. The minimum bactericidal concentrations (MBCs) for Gram-positive bacteria were 10 mM. Time-kill assay also showed that sucrose monocaprate significantly inhibit the growth of tested bacteria. The permeability of the cell membrane and intracellular proteins were both changed by sucrose monocaprate according to cell constituents' leakage, SDS-PAGE and scanning electron microscope assays. It is suggested that sucrose monocaprate, with both emulsifying and antibacterial activities, have a potential to serve as a safe multifunctional food additive in food industries.