Impact of processing on the antioxidant activity of a microorganism-enriched fish feed and subsequent quality effects on fillets of rainbow trout (Oncorhynchus mykiss)

Abstract

A broad range of compounds/ingredients for the substitution of fishmeal and fish oil in feeds for aquaculture was suggested over the last decades. This study aimed at characterizing changes in antioxidant activity from the raw materials over the fish feed production to the accumulation of potential health-beneficial antioxidants in the fish fillets of Oncorhynchus mykiss, when being fed with an innovative microorganism-based fish feed. The feed used consisted of a mix of the cyanobacterium Arthrospira sp., the microalgae Crypthecodinium cohnii, and the yeast Rhodotorula glutinis. These ingredients formed a balanced feed to demonstrate no limitations in fishmeal and oil substitution with regard to lipids, proteins, and antioxidants. The enrichment with bioactive compounds stabilizing the feed as well as enhancing bioactivity in the fish was successful. Also, radical scavenging activity was documented from the raw materials over the extrusion process to the accumulation in the fillets of rainbow trout (Oncorhynchus mykiss) over the whole fish production period of 16 weeks. As an additional quality parameter, the accumulation of pigments in the fish fillets was determined. The study revealed changes in the antioxidant profile over the whole value chain, which resulted in healthy organisms of higher quality compared to conventionally fed organisms.