The Effects of Two Forms of Ice on Microbiological and Physiochemical Properties of Barramundi (Lates calcarifer, Bloch) Fillets

Abstract

Barramundi (Lates calcarifer) fillets were subjected to two different ice forms (pre-freezing treatments: slurry ice [SI] and flake ice [FI]) for 0 (before freezing) and 1 h and 1, 2, 4, 8 and 16 days prior to blast freezing at −80C for 8 h. Fillets were then stored in a freezer at −20C for 20 days. Microbiological and physiochemical analysis were then carried out. Fillets that were exposed to pre-freezing treatments in FI demonstrated larger increase in total volatile base nitrogen, total viable count and pH; larger decrease in protein content; and smaller increase in moisture content compared with SI at the end of the frozen storage. Fillets exposed to pre-freezing treatments in FI are significantly (P < 0.05) lighter (L*), more red (a*) and more yellow (b*) than those in SI. All textural parameters fell significantly as storage time progressed in both FI and SI, with hardness falling to a greater extent in FI than SI. Practical Applications Slurry ice (SI), also known as fluid ice, slush ice, liquid ice or flow ice, consists of an ice–water suspension at a sub-zero temperature. It may be a valuable product for preserving seafood and is of substantial interest to seafood processors compared with flake ice (FI). These results demonstrate that the post-freezing quality of fillets was better preserved following up to 16 days of chilling in SI than in FI. Therefore, longer shelf life can be obtained by chilling barramundi fillets in SI.