Performance of zein-bound particles for delivery of riboflavin to early fish larvae

Zein-bound particles (ZBP), complex particles (CP) and lipid spray beads (LSB) were prepared and their performances were compared for delivering riboflavin to early fish larvae. Measures of performances of microparticles included inclusion, encapsulation, retention and delivery efficiencies in addition to T-50 (time to 50% retention) values. ZBP were not efficient in retaining riboflavin. Maximum retention (RE) and delivery (DE) efficiencies for riboflavin incorporated in ZBP occurred with 12.5% w/w lipid added to the particles. Substitution of menhaden oil with higher melting point lipids did not have any effect on retention of riboflavin. ZBP prepared by a spray-dry method had higher RE and DE compared with those of ZBP prepared by freeze-dry and spray-water methods. Elimination of water from the manufacture process resulted in significantly higher inclusion and encapsulation efficiencies of ZBP but did not affect retention rates. CP containing LSB and a dietary mixture bound together with zein had significantly higher retention and delivery efficiencies for riboflavin compared with those of ZBP. Fifty per cent of the initial riboflavin in CP was retained after 75 min of suspension in water. Although free LSB had higher retention efficiencies for riboflavin compared with CP, free LSB clumped and floated when suspended in water and were unavailable to fish larvae. Therefore, LSB should be incorporated into CP for more effective delivery of water-soluble nutrients in larval fish nutrition studies.