Solid Lipid Microparticles as leaching free, slow-release encapsulation system for Methionine in aquaculture

The enrichment of the fish feeds with the essential amino acids like methionine is a common strategy in Aquaculture. Leaching of the amino acids in the water environment and rapid absorption from the Gastro-Intestinal tract are some issues with the free amino acids supplementation strategy. The study aimed to investigate the use of Solid Lipid Microparticles as microencapsulation system for an essential amino acid, methionine. Solid Lipid Microparticles (SLMs) of two lipids, Trimyristin (TM) and Tristearin (TS) were fabricated using a melt emulsification method to encapsulate methionine and compared for their leaching protection and release characteristics in vitro and in vivo. Leaching study performed in the simulated water environment showed that the microparticles were leaching free. In simulated Gastro-Intestinal medias, release was minimal in the gastric media for both systems, while Trimyristin based microparticles showed better release in the simulated intestinal media than Tristearin based microparticles. Oral delivery study in Tilapia by mixing SLMs with the feed showed that the encapsulated methionine can provide slow release compared to the free methionine. Among the two lipids, Trimyristin based SLMs were found to be better digested by the fish. The encapsulation of methionine in lipids can be a suitable alternative for traditional free supplementation strategy for preventing leaching losses and better absorption characteristics for enhanced utilization by the fish.