Encapsulation systems for nutrients delivery in aquaculture

• Main Author: Mahotra, Manish
• Other Authors: Loo Say Chye Joachim
• Format: Thesis-Doctor of Philosophy
• Language: English
• Published: Nanyang Technological University 2022
• Subjects: Engineering::Materials::Biomaterials
• Online Access: https://hdl.handle.net/10356/161895
• Institution: Nanyang Technological University

The traditional delivery method of bioactive nutrients in aquaculture by simple mixing with feed often faces issues like the leaching of nutrients, rapid or low absorption by the body, and ineffective delivery of the nutrients to the site of absorption. In this thesis, it was hypothesized that microencapsulation systems for nutrient delivery can provide leaching protection, and targeted release of the nutrients for better absorption and utilization by the aquatic species. The large-scale demand of the aquaculture industry requires the encapsulation system to be fabricated using facile and scalable techniques while achieving the desired functionalities. Two types of encapsulation systems to solve the prevalent nutrient delivery issues were developed in this thesis. Firstly, crosslinked alginate microparticles were fabricated using a one-step, and scalable spray drying process. Two nutrients, a hydrophilic protein, and a hydrophobic beta-carotene were successfully encapsulated in the crosslinked alginate microparticles. The alginate microparticles were stable in water due to the crosslinking and prevented the leaching of the nutrients. Furthermore, the release was mainly observed in the intestinal fluid providing a targeted delivery. Secondly, lipid-based Solid Lipid Microparticles (SLMs) of two lipids, Trimyristin (Dynasan 114) and Tristearin (Dynasan 118) were fabricated as leach-free encapsulation systems for the delivery of a hydrophilic essential amino acid. The SLMs were prepared using the melt-emulsification technique. The SLMs provided resistance to the leaching of the amino acid in the aquatic environment and showed slow, intestinal targeted release. The release was mediated by the lipolysis of the lipids and Dynasan 114 based SLMs were found to be suitable for achieving the desired release in the Gastrointestinal (GI) tract. Additionally, the incorporation of SLMs in the feed was found to be safe for oral use and showed similar growth performance as free amino acid incorporated feed in a growth trial conducted using Tilapia. Furthermore, the SLMs were also suitable for encapsulation of a hydrophobic nutrient, Curcumin. Overall, the encapsulation systems developed in this thesis were found to be suitable for the encapsulation of different aquaculture-related nutrients and can be used as an alternative to the traditional supplementation of nutrients in aquaculture feeds. The use of cost-effective materials, and scalable techniques provide solutions for future investigations and commercial use of the encapsulation systems in aquaculture.