Comparative Variations of Extractive Nitrogenous Components and Quality in Fresh Muscle and Dried Product of Rabbitfish (Siganus fuscescens) in Taiwan

Abstract

Variations in the level of quality and extractive nitrogenous components were investigated in the fresh muscle and commercial dried products of rabbitfish Siganus fuscescens collected from Penghu, Taiwan. The respective freshness quality for fresh muscle is as follows: trimethylamine oxide (TMAO), 29.50 mg N/100 g; trimethylamine (TMA), 2.30 mg N/100 g; NH3, 6.61 mg/100 g; total volatile basic nitrogen (TVBN), 13.32 mg/100 g; aerobic plate count, 1.53 log CFU/g; and K-value, 28.80%. The respective freshness quality for dried products is as follows: TMAO, 43.44 mg N/100 g; TMA, 25.56 mg N/100 g wet wt.; NH3, 52.00 mg/100 g wet wt.; TVBN, 149.98 mg/100 g; aerobic plate count, 4.16 log CFU/g; and K-value, 89.73%. The major fatty acids in the fresh muscle and dried products are C16:0, C18:1 n-9, C18:0, C16:1 C22:6 n-3, and C22:5 n-3. The major nucleotide compound is inosine 5ʹ-monophosphate (IMP) in the fresh muscle (68%) and hypoxanthine (Hx) in the dried products (79%). The level of total free amino acids in the dried products shows significant variation depending on the processing method of the plants.