The Effects of Postmortem Time on Muscle Trout Biochemical Composition and Structure

Area of Science:

• Aquatic science
• Food science
• Biomarker discovery

Background:

• Fish industry operators face challenges processing fish at various postmortem times, impacting quality, safety, and value.
• Objective identification of biomarkers is crucial for predicting fish aging and optimizing processing.
• A comprehensive longitudinal characterization of postmortem aging is needed.

Purpose of the Study:

• To analyze the postmortem aging process in trout over a 15-day period.
• To identify objective biomarkers for predicting postmortem aging.
• To explore novel methods for rapid assessment of fish freshness.

Main Methods:

• Longitudinal analysis of trout postmortem aging over 15 days.
• Quantitative physicochemical measurements (pH, color, texture, aw, proteolysis, protein solubility).
• Histological analyses, transmission electron microscopy (TEM), and label-free Fourier-transform infrared (FTIR) micro-spectroscopy with Support Vector Machine (SVM) and Principal Component-Linear Discriminant Analysis (PC-DA) models.

Main Results:

• Conventional physicochemical methods showed minimal changes in protein denaturation, solubility, and pH.
• Histology revealed fiber ruptures after 7 days; TEM showed sarcomere disorganization after 7 days.
• FTIR micro-spectroscopy combined with SVM accurately predicted postmortem time; PC-DA models identified biomarkers for Day 7 and Day 15.

Conclusions:

• Postmortem aging significantly impacts trout quality, with structural changes occurring after 7 days.
• Label-free FTIR micro-spectroscopy offers a promising method for rapid, objective assessment of fish freshness.
• This study provides insights into postmortem aging and biomarker identification for the fish industry.