Manufacturing pellets with different binders: Effect on water stability and feeding response in juvenile Cherax albidus

Abstract

In this study, we used natural polysaccharides (pectin, alginate and chitosan) as binders to generate pellets for crayfish feeding. Pellets were produced by cold extrusion in order to preserve nutrients from degradation and reduce energy consumption. Thereafter, pellets were submitted to a coating procedure, with the aim of improving pellet stability in water. Pellet water stability was analyzed by monitoring the diameter of the released particles in water over progressive time intervals up to 24 h, employing a Low Angle Laser Light Scattering Technique. Alginate containing pellets released particles with a smaller diameter than chitosan and pectin containing pellets, indicating that alginate containing pellets disaggregated more and therefore were less stable in water than the other pellet types. The effects of the different polysaccharide containing pellets were evaluated on crayfish feeding response employing juvenile Cherax albidus. The feeding experiment was carried out for 12 weeks, at the end of which growth parameters and the activity of amylase, lipases and proteases in the gastric juice, hepatopancreas and intestine were recorded. Crayfish fed pectin containing pellets exhibited a significant weight gain. Digestive enzyme activities did not statistically show significant differences in the digestive tract except for amylase that was significantly higher in the intestine of animals fed pectin containing pellets. Our data indicate that pectin and chitosan pellets showed the best water stability performances, moreover pectin pellets brought about the highest body weight gain and affected the amylase profile in the intestine of juvenile Cherax albidus.