Polylactic acid (PLA) is a very promising biodegradable, renewable, and biocompatible polymer. Aside from its production, its application field is also increasing, with use not only in commodity applications but also as durables and in biomedicine. In the current PLA production scheme, the most expensive part is not the polymerization itself but obtaining the building blocks lactic acid (LA) and lactide, the actual cyclic monomer for polymerization. Although the synthesis of LA and the polymerization have been studied systematically, reports of lactide synthesis are scarce. Most lactide synthesis methods are described in patent literature, and current energy-intensive, aselective industrial processes are based on archaic scientific literature. This Review, therefore, highlights new methods with a technical comparison and description of the different approaches. Water-removal methodologies are compared, as this is a crucial factor in PLA production. Apart from the synthesis of lactide, this Review also emphasizes the use of chemically produced racemic lactic acid (esters) as a starting point in the PLA production scheme. Stereochemically tailored PLA can be produced according to such a strategy, giving access to various polymer properties.

Candida rugosa lipase (CRL) is a very versatile and widely used lipase in the aroma and flavor industry, the fat and oil industry, the pharmaceutical industry and is also applicable as a biosensor. The present paper discusses recent developments on the molecular level of CRL, the biocatalytic reactivity of several Lip isoenzymes, diverse immobilization strategies of the enzyme and its broad (substrate) specificities in different fields. Furthermore, an overview is given of future applications with CRL such as the enantioselective hydrolysis of racemic lactate esters produced out of sugars and the production of biodiesel out of vegetable oil. These processes have been tried on laboratory scale but still need further optimization for industrialization.

Review: [67 refs.