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A new biocatalyst of lipase B from Candida antarctica (MCI-CALB) immobilized on styrene-divinylbenzene beads (MCI GEL CHP20P) was compared with the commercial Novozym 435 (immobilized lipase) in terms of their performances as biocatalysts for the esterification of acetic acid and n-butanol. The effects of experimental conditions on reaction rates differed for each biocatalyst, showing different optimal values for water content, temperature, and substrate molar ratio. MCI-CALB could be used at higher acid concentrations, up to 0.5 M, while Novozym 435 became inactivated at these acid concentrations. Although Novozym 435 exhibited 30% higher initial activity than MCI-CALB for the butyl acetate synthesis, the reaction course was much more linear using the new preparation, meaning that the MCI-CALB allows for higher productivities per cycle. Both preparations produced around 90% of yield conversions after only 2 h of reaction, using 10% (mass fraction) of enzyme. However, the main advantage of the new biocatalyst was the superior performance during reuse. While Novozym 435 was fully inactivated after only two batches, MCI-CALB could be reused for six consecutive cycles without any washings and keeping around 70% of its initial activity. It is proposed that this effect is due to the higher hydrophobicity of the new support, which does not retain water or acid in the enzyme environment. MCI-CALB has shown to be a very promising biocatalyst for the esterification of small-molecule acids and alcohols.

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The synthesis of pineapple flavour (butyl butyrate) catalysed by lipase from Rhizomucor miehei has been optimized using central composite design and response surface methodology. Initially, the best butyric acid concentration in the mixture was defined and found that 1 M butyric acid presented the highest initial reaction rate. The reaction parameters substrate molar ratio, enzyme content, and initial added water were evaluated in the central composite design with the reaction conversion yield as the dependent variable. The optimal conditions for butyl butyrate synthesis were found to be substrate molar ratio of 3.6:1 butanol:butyric acid; enzyme content of 6.5% of substrate mass fraction; added water 0.0% of substrate mass fraction. Under these conditions, over 90% of conversion was obtained in 16 h of reaction. Enzyme reuse was tested performing a treatment before each batch by washing the enzyme system with n-hexane, or simply reusing the biocatalyst in a new fresh reaction. Direct enzyme reuse caused a rapid decrease on the enzyme activity, while washings with n-hexane allowed the enzyme to be reused for six cycles keeping around 75% of its original activity.

Glycoside hydrolases (GH) are enzymes capable to hydrolyze the glycosidic bond between two carbohydrates or even between a carbohydrate and a non-carbohydrate moiety. Because of the increasing interest for industrial applications of these enzymes, the immobilization of GH has become an important development in order to improve its activity, stability, as well as the possibility of its reuse in batch reactions and in continuous processes. In this review, we focus on the broad aspects of immobilization of enzymes from the specific GH families. A brief introduction on methods of enzyme immobilization is presented, discussing some advantages and drawbacks of this technology. We then review the state of the art of enzyme immobilization of families GH1, GH13, and GH70, with special attention on the enzymes β-glucosidase, α-amylase, cyclodextrin glycosyltransferase, and dextransucrase. In each case, the immobilization protocols are evaluated considering their positive and negative aspects. Finally, the perspectives on new immobilization methods are briefly presented.

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β‐Glucosidases from two different commercial preparations, Pectinex Ultra SP‐L and Celluclast® 1.5L, were immobilized on divinylsulfone (DVS) supports at pH 5.0, 7.0, 9.0, and 10. In addition, the biocatalysts were also immobilized in agarose beads activated by glyoxyl, and epoxide as reagent groups. The best immobilization results were observed using higher pH values on DVS‐agarose, and for Celluclast® 1.5L, good results were also obtained using the glyoxil‐agarose immobilization. The biocatalyst obtained using Pectinex Ultra SP‐L showed the highest thermal stability, at 65°C, and an operational stability of 67% of activity after 10 reuses cycles when immobilized on DVS‐agarose immobilized at pH 10 and blocked with ethylenediamine. The β‐glucosidase from Celluclast® 1.5L produced best results when immobilized on DVS‐agarose immobilized at pH 9 and blocked with glycine, reaching 7.76‐fold higher thermal stability compared to its free form and maintaining 76% of its activity after 10 successive cycles. The new biocatalysts obtained by these protocols showed reduction of glucose inhibition of enzymes, demonstrating the influence of immobilization protocols, pH, and blocking agent.

BACKGROUND This study investigated the use of core–shell biocatalysts, synthesized using recombinant lipase B from Candida antarctica (CALB), for the production of isopropyl palmitate and the optimization of this biocatalytic route. RESULTS Initially, three distinct core–shell biocatalysts, were evaluated for the production of isopropyl palmitate and the CALB‐P(S‐co‐DVB)/P(S‐co‐DVB) biocatalyst (biocatalyst made of polystyrene‐co‐divinylbenzene core–shell particles) was the most suitable biocatalyst for this purpose. The effect of organic solvents – n‐hexane, isooctane, n‐heptane and cyclohexane – in the ester conversion was evaluated, and the most suitable solvent was the isooctane. The optimal reaction conditions were pursued conducting an optimization statistical analysis. The most suitable reaction conditions were identified: reaction temperature, 55°C; substrate molar ratio, 1:1.42 (palmitic acid: isopropyl alcohol); biocatalyst content, 24% w/w. Finally, the reuse of the biocatalyst was evaluated and the relative enzymatic activity remained up to 50% after the fourth cycle. CONCLUSION Results were compared with commercial biocatalyst and the home‐made enzymatic biocatalyst (CALB‐P(S‐co‐DVB/PS‐co‐DVB) showed promise for application in the synthesis of isopropyl palmitate. The optimization study improved reaction conversion from 30% to 78%. The home‐made biocatalysts exhibited better performance for the synthesis of isopropyl palmitate compared with the commercial Novozym 435, using the same enzymatic activity. © 2018 Society of Chemical Industry