Changes in Freshness of Steak and Loin Tuna (Thunnus albacares) during 15 Day-chilled Storage

Abstract

The present study was undertaken to assess the effect of chilled storage on the quality of steak and loin tuna by studying the changes in chemistry, microbiology and sensory attributes. Six fresh tuna unloaded in Pelabuhan Ratu, West Java, Indonesia were transported to Jakarta with proper icing. Upon arrival at the factory, the fish were carefully cut into steak and loin, followed by storage at chilled temperature (0-4°C) for 15 days in the laboratory. Changes in freshness were monitored by 3 days interval, including K-value, histamine, heavy metals, microbiology and sensory test. The initial values of K-value, histamine contents, total microbial count and histamine producing bacteria were 2.01-13.74%, 1.28-1.61 mg/100 g, 2.68-5.10 log CFU g-1 and 1.35-2.20 log CFU g-1 , respectively, whereas mercury and cadmium concentrations (markers of environmental pollution) were around the Indonesian standards. During chilled storage at 0-4°C for 15 days, the K-value of tuna steak constantly increased from 2.85-29.88% and the histamine content of it also increased from 1.41-5.60 mg/100 g while total microbial count and histamine producing bacteria fluctuated within the acceptable levels, i.e., 2.68-5.10 log CFU g-1 ; and 1.35-2.20 log CFU g-1 , respectively. However, the sensory scores by 7 trained panelists gradually decreased with storage time and both steak and loin tuna were judged as not fresh after 15 days of chilled storage.