Chemical, sensory and microbiological stability of freeze-dried Nile tilapia croquette mixtures

Abstract

The stability of tilapia croquette mixtures was evaluated for 240 days, through analyses of water activity (aw), lipid oxidation (TBARS) and sensory and microbiological assays. The control mixture was composed of tilapia mince, wheat and rye flours and seasonings while the enriched mixture also contained flaxseed flour. Aw increased significantly over time, from 0.1666 to 0.5392 for the control mixture and from 0.0554 to 0.5415 for the enriched mixture. TBARS values increased from 0.08 to 0.38 mg kg−1 for the control mixture and from 0.11 to 0.40 mg kg−1 malondialdehyde (MDA) for the enriched mixture. Appearance, texture and overall acceptance of the control mixture remained constant and the flavour improved during storage, while sensory attributes of the enriched mixture did not change. Overall acceptance was nearly 8 for the control mixture and 6 for the enriched mixture using a 9-point hedonic scale, where 9 = ‘like a lot’ and 1 = ‘dislike intensely’. Microbiological parameters did not exceed the legal limits allowed for consumption. Both mixtures remained suitable for consumption after 240 days.