Lipase-catalyzed esterification of 2-monoricinolein for 1,2(2,3)-diricinolein synthesis

The purpose of this investigation was to develop conditions for producing 2-monoricinoleoyl DAG. We used lipase-catalyzed hydrolysis of triricinolein to obtain 2-monoricinolein and thereafter synthesized 1,2(2,3)-diricinolein through esterification of 2-monoricinolein, using ricinoleic acid as the acyl donor. Five different 1,3-specific immobilized lipases were tested for the initial methanolysis reaction: Candida antarctica type B, Rhizomucor miehei, Rhizopus oryzae (ROL), Thermomyces lanuginosus, and Aspergillus niger. For the second esterification reaction, we investigated these five lipases plus Pseudomonas cepacia, Penicillium roquefortii, Candida rugosa, and Pseudomonas fluorescence. Toluene and diisopropyl ether (DIPE) were examined as reaction media at a water activity of 0.11. ROL in DIPE gave the highest yield of 2-monoricinolein from triricinolein, 78% after 3 h of reaction. The isolated 2-monoricinolein was esterified with ricinoleic acid for synthesis of 1,2(2,3)-diricinolein. ROL in DIPE gave the highest yield of 1,2(2,3)-diricinolein, 58% after 1 h of reaction, and NMR analysis showed that the purity was 97.2%. This methodology can used for synthesizing radiolabeled 1,2(2,3)-diricinolein to study lipid biosynthesis in castor and other oilseeds.     

The dry-to-wet transition of fiber networks—Return to mechanical stability

In this article, we provide a comprehensive experimental, numerical, and theoretical explanation of the dry-to-wet transition of nonbonded fiber networks made of natural fibers. Given that the main functionality of many common products consisting of fluff pulp fiber networks requires absorption of liquids, we focus on understanding the solid volume fraction transition from a dry to a wet state as a crucial component for controlling properties such as permeability and capillary pressure, on which product function eventually depends. From studying the wetting of fluff pulp fiber networks with a distribution of fiber lengths, we show that the change in the solid volume fraction going from dry to wet state is driven by the disappearance of fiber–fiber adhesion. The mechanically stable state to which the network transitions is independent of its prior dry solid volume fraction and predetermined primarily by the fiber aspect ratio.