Effect of pre-treatment and smoking process (cold and hot) on chemical, microbiological and sensory quality of mackerel (Scomber scombrus)

The sensory, hygienic, toxicological and nutritional profiles of hot- and cold-smoked mackerel samples were studied with various pre-treatments. The panellists assessed all smoked samples as barely to quite acceptable products whilst the product immersed in 120 g kg(-1) sodium chloride and 60 g kg(-1) fructose prior to smoking was assessed as very acceptable regarding its sensory characteristics. The available lysine in all hot smoked samples was reduced to the same extent (32%) whilst a very good correlation (r = 0.912) was observed between loss of available lysine and colour formation of the cold-smoked products, indicating the high contribution of lysine in the interactions with carbonyls. Histamine was found in highly unacceptable levels even in the unprocessed samples (600 mg kg(-1)) and strongly increased (2220 and 2250 mg kg(-1)) in the cold- and hot-smoked samples, respectively, due to all treatments. These are levels which would be expected to cause symptoms of scombrotoxin poisoning. Benzo(a)pyrene, fluoranthene and perylene were at high levels both in cold- (2.1, 4.3 +/- 0.04 and 7.2 +/- 0.05 mug kg(-1)) and hot-smoked samples (9.2, 7.8 +/- 0.03 and 9.4 +/- 0.14 mug kg(-1), respectively) and were, as expected, influenced by the temperature. The aerobic bacteria remained at acceptable levels, since salt and high temperature prevent bacterial growth. (C) 2004 Society of Chemical Industry.