359: Effect of Green Tea Extract Sprayed Using a Novel Refrigerated Chamber-Type Spray Chilling System on Melanosis and Quality of Refrigerated Pacific White Shrimp (Litopenaeus Vannamei)

Introduction

Interest in natural antioxidants and antimicrobials as alternatives to synthetic preservatives is growing, with GTE being widely studied for use in the shrimp industry. Dipping, the most common application method, is time-consuming and poses contamination risks. This study evaluates the effectiveness of a novel RCS in applying GTE to control melanosis and preserve the quality of white shrimp during refrigerated storage.

Methods

GTE solutions (1%, 3%, and 5% w/v) were prepared by dissolving GTE in distilled water at room temperature. An RCS, equipped with an air compressor, regulators, a peristaltic pump, and a two-fluid nozzle, was used for treatment. Fresh whole shrimp (18±2 g, with heads) were divided into five groups: untreated control (C1), sodium meta-bisulfite-treated control (1.25% w/v, C2), and GTE-treated groups (T1: 1%, T2: 3%, T3: 5%). Five shrimp per group were treated for 1 min in the RCS (liquid flow rate: 2 mL/min; air pressure: 14.5 psi; nozzle-to-stage distance: 170 mm; droplet size: 10.72±0.49 μm; droplet velocity: 98 m/s). Treated shrimp were stored at 4°C for 12 days and analyzed at 2-day intervals for Pseudomonas spp., total aerobic counts, muscle pH, moisture content, melanosis score (0–10), color, and TBARS. Statistical analysis was performed at α = 0.05.

Results

The C1 group exceeded the Pseudomonas spp. safety limit (7 log CFU/g) by day 6, whereas the C2 and GTE-treated samples surpassed this limit by day 9. Among the GTE treatments, T3 (5% GTE) exhibited the lowest Pseudomonas spp. count (5.23 ± 0.02 log CFU/g) and total aerobic count (6.20±0.01 log CFU/g) on day 9. On day 9, T3 demonstrated the most favorable physicochemical properties, including a pH of 7.10±0.34 and a moisture content of 87.12±1.02%, with no significant differences from C2. Both T3 and C2 showed the lowest melanosis score (6), which was consistent with their color data. Lipid oxidation, measured as TBARS, was significantly lower (p < 0.05) in T3 (0.16±0.03 mg MDA/kg) compared to both control groups.

Significance

This study demonstrated the potential of using the novel RCS as an effective method to apply GTE for preserving shrimp quality and reducing melanosis during refrigerated storage for up to 9 days.

Authors: Mario Melendez, Tharindu Trishan Dapana Durage, Mariel Benigno, Chien-I Hsu, Kaushalya Wickramasinghe, Subramaniam Sathivel