PREPARATION AND CHARACTERIZATION OF A COMPLEX MICROENCAPSULATED DIET FOR STRIPED BASS MORONE-SAXATILIS LARVAE

The nutritional requirements of marine fish larvae are not well unders tood, primarily due to the lack of biochemically defined diets accepta ble by the larvae. This study describes the methodology for the prepar ation and the characterization of a complex protein-walled microcapsul e (CPWC) containing lipid-walled capsules (LWC). The CPWC were prepare d by atomizing a mixture of casein, LWC and other dietary materials in to a cyclohexane solution containing 1% (v/v) cross-linking reagent, a dipoyl chloride. The primary purpose of complex microencapsulation was to allow the gradual release of low molecular weight phagostimulants and nutrients from the cross-linked protein wall. To determine the rel ease kinetics of low molecular weight compounds from the complex diet, a solution of the amino acid, lysine, was encapsulated in LWC and its leaching rate from CPWC was assessed. A batch of conventional protein -walled capsules (PWC) were also prepared by mixing lysine with casein . Tile release of lysine from CPWC was significantly lower than that m easured from conventional PWC (p < 0.05). Nearly 45% of the total lysi ne leached out of freeze-dried PWC within 5 min of hydration, reaching 100% after 2 h. CPWC, on the other hand, efficiently retained encapsu lated lysine, releasing only 25% after 2 h. In-vitro experiments indic ated that CPWC were readily digested by the crude enzyme extract from striped bass larvae and purified porcine pepsin and trypsin.