Improved activity and stability of Rhizopus oryzae lipase via immobilization for citronellol ester synthesis in supercritical carbon dioxide

Improved biocatalytic activity of steapsin lipase in supercritical carbon dioxide medium for the synthesis of benzyl butyrate: A commercially important flavour compound

Enzymatic synthesis of flavours, fragrances and food additives compounds have great demand and market value. Benzyl butyrate is commercially important flavour and food additive compound having global use around 100 metric tons/year and widely used in various industrial sectors. However, industrial synthesis of food additive benzyl butyrate is carried out by conventional chemical process which demands for the green biobased sustainable synthetic process. The present work reports steapsin catalyzed synthesis of benzyl butyrate for the first time in supercritical carbon dioxide (Sc-CO2) reaction medium. All reaction variables are optimized in details to obtain competent conversion of 99% in Sc-CO2 reaction medium. The developed steapsin catalyzed synthesis in Sc-CO2 medium offered almost four-fold higher conversion to benzyl butyrate than organic (conventional) solvent. The steapsin biocatalyst was effectually recycled up to five reaction cycles in Sc-CO2 medium. Moreover, the developed steapsin catalyzed protocol in Sc-CO2 medium was extended to synthesize different ten industrially significant flavour fragrance compounds that offers 99% conversion and three to five-folds higher conversion than organic medium. Thus, the present steapsin catalyzed protocol offered improved synthesis of various commercially significant flavour compounds in Sc-CO2. medium.

Supercritical CO2 as a Valuable Tool for Aroma Technology

This review addresses the possibilities of using supercritical carbon dioxide (SC-CO₂) in the flavor industry in extraction and fractionation processes and its use as a reaction medium to generate aroma esters. The advantages and disadvantages are presented, comparing SC-CO₂ processing with traditional methods. The most distinguishable features of SC-CO₂ include mild reaction conditions, time savings, fewer toxicity concerns, higher sustainability, and the possibility of modulating solvent selectivity according to the process conditions (such as pressure and temperature). Thus, this review indicates the potential of using SC-CO₂ to obtain a high selectivity of compounds that can be applied in aroma technology and related fields.

Lipase immobilization on biodegradable film with sericin

An ecofriendly and low-cost film composed by cassava starch, polyvinyl alcohol, and sericin blend (CS-PVA-SS) was synthesized, characterized, and applied as a novel support for Botryosphaeria ribis EC-01 lipase immobilization by enzyme-film-enzyme adsorption. Film revealed thickness between 230 and 309 μm and higher flexibility and malleability in comparison with film without SS. Based on p-nitrophenyl palmitate hydrolysis reaction, the activity retention of immobilized lipase was 987%. For optimal conditions, the yield in ethyl oleate was 95% for immobilized enzyme. Maximum yield was obtained at 49°C, molar ratio oleic acid:ethanol of 1:3, 1.25 g lipase film or 50 U (1.03 ± 0.03 mg protein) and 30 h. Even after seven cycles of use, immobilized lipase showed 52% reduction in ester yield. Biodegradable and biorenewable film is a promising material as a support to immobilize lipases and application in biocatalysis.

Synthesis of lipophilic arbutin ester by enzymatic transesterification in high pressure carbon dioxide

In this study, a novel one-step enzymatic acylation was developed for the synthesis of hydrophobic arbutin ester, by using supercritical carbon dioxide (SC-CO₂) as the reaction solvent. Immobilized Novozym 435 from Candida antarctica was identified as the best biocatalyst for producing arbutin palmitate through transesterification between arbutin and palmitic acid ethyl ester in SC-CO₂. A transesterification yield of 85.21 % was obtained in batch operation using palmitic acid ethyl ester as the acyl donor, hexane/propylene glycol as the co-solvent and Novozym 435 as the enzyme at 10 MPa and 60 °C for 20 h in SC-CO₂. The yield of arbutin palmitate increased with increasing temperature over the range of 40-60 °C in the current study. Operating at an arbutin/palmitic acid ethyl ester molar ratio of 5.0, the conversion of arbutin decreased, probably due to an inhibitory effect of the high concentration of palmitic acid ethyl ester on the enzyme. The 38 % original enzyme activity of Novozym 435 was maintained after being used for 3 cycles (60 h) under optimized conditions.

Rhizopus oryzae Lipase, a Promising Industrial Enzyme: Biochemical Characteristics, Production and Biocatalytic Applications

Lipases are biocatalysts with a significant potential to enable a shift from current pollutant manufacturing processes to environmentally sustainable approaches. The main reason of this prospect is their catalytic versatility as they carry out several industrially relevant reactions as hydrolysis of fats in water/lipid interface and synthesis reactions in solvent-free or non-aqueous media such as transesterification, interesterification and esterification. Because of the outstanding traits of Rhizopus oryzae lipase (ROL), 1,3-specificity, high enantioselectivity and stability in organic media, its application in energy, food and pharmaceutical industrial sector has been widely studied. Significant advances have been made in the biochemical characterisation of ROL particularly in how its activity and stability are affected by the presence of its prosequence. In addition, native and heterologous production of ROL, the latter in cell factories like Escherichia coli, Saccharomyces cerevisiae and Komagataella phaffii (Pichia pastoris), have been thoroughly described. Therefore, in this review, we summarise the current knowledge about R. oryzae lipase (i) biochemical characteristics, (ii) production strategies and (iii) potential industrial applications.

Lipase-Catalyzed Esterification of Geraniol and Citronellol for the Synthesis of Terpenic Esters

This article describes the synthesis of terpenic esters derived from geraniol and citronellol (geranyl and citronellyl alkanoates) through esterification reactions catalyzed by the immobilized lipases from Thermomyces lanuginosus (Lipozyme TL IM®) and Candida antarctica (Novozym 435®). Geraniol was esterified with oleic, lauric, and stearic acids; and citronellol was esterified with oleic and stearic acids. For all the synthesized flavor esters, the best conditions were 35 °C, and the molar ratio between acid and alcohol was 1:1. Geranyl and citronellyl alkanoates reached yields between 80-100% within 4 h of reaction. For the synthesis of the citronellyl and geranyl oleate, higher yields were obtained in the absence of organic solvents. For the esters from lauric and stearic acids, using solvent was indispensable to improve the miscibility between the substrates. The reuse of Novozym 435® and Lipozyme TL IM® was performed for two more cycles after the first use, with yields higher than 60%. The results demonstrated the efficiency of the reaction catalyzed by these two commercial enzymes and the feasibility of the methodology for the production of synthetic flavor esters through enzymatic catalysis. The flavor esters synthesized were not described in the literature up to the date, giving this research an innovative feature.

A Green Process for Synthesis of Geraniol Esters by Immobilized Lipase from Candida Antarctica B Fraction in Non-Aqueous Reaction Media: Optimization and Kinetic Modeling

Enzymatic synthesis of molecules such as flavors, perfumes and fragrances has a great commercial advantage of being marketed as “natural” and also it offers exquisite selectivity of enzymes that can be superior over chemical catalysis. The current work focuses on the enzymatic synthesis of geranyl acetate as model compound, including optimization of reaction conditions such as nature of catalyst, reaction media, speed of agitation, mole ratio and temperature. A variety of esters were also synthesized. Geraniol was esterified with various acids, aromatic esters and vinyl esters in 1:4 molar ratio. Among all vinyl ester was the best giving in good yield (77–100 %) as compared to aromatic esters (5–82 %) and acids (7–31 %). Novozym 435 was found to be most active catalyst with ~96 % conversion and 100 % selectivity in 60 min at 55 °C in n-heptane as solvent for geranyl acetate. The maximum reaction rate was estimated (Vmax = 0.2712 mol L−1 min-1) by using the double reciprocal plot. It is a ternary complex (ordered bi-bi) mechanism with inhibition by geraniol.

Gd(OTf)3-catalyzed synthesis of geranyl esters for the intramolecular radical cyclization of their epoxides mediated by titanocene(III)

A selective and mild method for the esterification of a variety of carboxylic acids with geraniol is developed. We demonstrated that the use of triphenylphosphine, I2, 2-methylimidazole or imidazole and a catalytic amount of Gd(OTf)3 resulted to be more active than the previous protocols, providing a 16-membered library of geranyl esters in higher yields and in shorter reaction times. The use of essential oil of palmarosa (Cymbopogon martinii), enriched with geraniol, as a raw material for the synthesis of the target compounds complemented and proved how sustainable and eco-friendly this protocol is. Finally, the selective 6,7-epoxidation of the obtained geranyl esters led us to study their regio-controlled radical cyclization mediated by titanocene(III) for the synthesis of novel (8-hydroxy-9,9-dimethyl-5-methylene cyclohexyl)methyl esters in moderate yields and with excellent stereoselectivities.

Utilization of fish meal and fish oil for production of Cryptococcus sp. MTCC 5455 lipase and hydrolysis of polyurethane thereof

Fish meal has been used as an additional nitrogen source and fish oil as inducer for the growth and production of lipase from Cryptococcus sp. MTCC 5455. A response surface design illustrated that the optimum factors influencing lipase production were fish meal, 1.5 %, w/v, Na2HPO4, 0.2 %, w/v, yeast extract, 0.25 %, w/v and sardine oil, 2.0 %, w/v with an activity of 71.23 U/mL at 96 h and 25 °C, which was 48.39 % higher than the conventional one-factor-at-a-time method. The crude concentrated enzyme hydrolyzed polyurethane (PUR) efficiently and hydrolysis was 94 % at 30 °C and 96 h. The products, diethylene glycol and adipic acid were quantified by HPLC and scanning electron microscopic studies of the degraded polymer showed significant increase in size of the holes from 24 to 72 h of incubation. Hydrolysis of PUR within 96 h makes the lipase novel for disposal of PUR and provides an innovative solution to the problems created by plastic wastes.

Sn(ii)-catalyzed β-citronellol esterification: a Brønsted acid-free process for synthesis of fragrances at room temperature

Simple SnCl₂·2H₂O was demonstrated to be able to catalyze β-citronellol esterification with acetic acid at room temperature under solvent-free conditions, achieving high conversion and ester selectivity (ca. 88% and 99%, respectively).

Evaluation of structure and hydrolysis activity of Candida rugosa Lip7 in presence of sub-/super-critical CO₂

This work aimed to assess the effect of sub-/super-critical CO₂ on the structure and activity of Candida rugosa Lip7 (CRL7) in its solution form. The structure was examined by SDS-PAGE gel electrophoresis, circular dichroism (CD) and fluorescence spectra photometry. Results revealed that the primary structure remained intact after sub-/super-critical CO₂ treatment, and the secondary structure altered at the pressure of 10 MPa and temperature 40°C for 30 min incubation, but it was reflex to its native form with increasing incubation time up to 150 min under 10 MPa and 40 °C. Meanwhile, the tertiary structure via fluorescence spectra analysis showed that the intensity of the maximal emission wavelength at 338 nm decreased under the conditions of 10 MPa and 40°C for 150 min. Furthermore, the residue hydrolysis activity and kinetics constants (V(max) and K(m)) of CRL7 treated with sub-/super-critical CO₂ were also investigated. In cases of 6 MPa and 35°C, or 10 MPa and 40°C for 30 min, activity variance of CRL7 was maybe caused by its secondary structure alteration. But in case of 10 MPa and 40°C for 150 min, the tertiary structure change was perhaps responsibility for CRL7 activity enhancement.

Supercritical synthesis of biodiesel

The synthesis of biodiesel fuel from lipids (vegetable oils and animal fats) has gained in importance as a possible source of renewable non-fossil energy in an attempt to reduce our dependence on petroleum-based fuels. The catalytic processes commonly used for the production of biodiesel fuel present a series of limitations and drawbacks, among them the high energy consumption required for complex purification operations and undesirable side reactions. Supercritical fluid (SCF) technologies offer an interesting alternative to conventional processes for preparing biodiesel. This review highlights the advances, advantages, drawbacks and new tendencies involved in the use of supercritical fluids (SCFs) for biodiesel synthesis.