Chemical composition and pH value of rainbow trout (Oncorhynchus mykiss) and river trout (Salmo trutta fario) meat grown in fish ponds

Abstract

pH value, basic chemical composition (water, proteins, fats and ash) as well as energy value of rainbow (standard and golden type) and river trout meat were investigated. The fish have been grown and fed in the same way in two different ponds with pure spring water. Chemical composition was determined by standard methods. pH value was measured using pH meter by direct inserting the combined probe into the comminuted and homogenized meat, being kept for 24 hours in refrigerator (2-4°C), according to standard ISO method. It was found that pH value of the standard rainbow type, golden rainbow type and the river trout meat was 6.36, 6.40 and 6.33, respectively. Meat from standard rainbow trout contained 75.92% water, 19.35% proteins, 2.53% fat, 1.14% ash and 430.62 kJ/100 g, compared to the golden rainbow type of trout containing 74.68%, 19.37%, 3.57%, 1.24% and 471.20 kJ/100g, respectively. The values for the above mentioned items in river trout meat were 75.76%, 19.39%, 2.44%, 1.30% and 427.88 kJ/100 g, respectively. The differences in water, fat content and the energy value of meat between golden rainbow trout and the other two trout types were significant (P <0.05).