COST‐EFFECTIVE AND NONDESTRUCTIVE TEXTURAL ASSESSMENT OF FISH FRESHNESS VIA SYSTEM IDENTIFICATION PRINCIPLES

Abstract

ABSTRACT This paper introduces a cost‐effective, rapid and nondestructive methodology exploiting system identification principles for monitoring the textural changes of fish during ice storage. Gilthead sea bream stored in ice for 0 (freshly killed) and 6 days are placed on a spring‐based weight scale and suffer a single, light and reproducible shock by a mallet. The reaction force, measured by the scale and recorded (throughout time) as an electrical signal, is analyzed via system identification principles for estimating the fish stiffness and damping ability in each freshness stage. Results highlight significant and highly repeatable reductions of the fish damping in 6 days of ice storage, due to textural changes undermining its ability of absorbing the shock‐induced energy. The methodology correlates well with organoleptic findings, describing significant elasticity loss in the 6th day ice‐stored fish. Thus, the proposed nondestructive methodology shows potential for cost‐effectively estimating textural changes in fish and for correlating them with freshness. PRACTICAL APPLICATIONSThe present methodology showed that a cost‐effective experimental setup used along with simple but carefully executed tests and basic principles of system identification may reliably measure physical changes in fish, even in high‐quality shelf‐life stages. Thus, it could serve as an improvement upon methods indicating degree of spoilage. Its potential practical applications include fisheries and the aquaculture industry, as well as fish freshness evaluation in lab tests.