Turkey liver: Physicochemical characteristics and functional properties of protein fractions

Turkey liver is an important edible meat by-product. However, it is generally unprocessed, underutilized and low-priced compared to mammalian livers. The present investigation was conducted to provide information on physicochemical composition and functional characteristics of turkey liver. Proximate composition (%) was: moisture (72.3 +/- 1.2), protein (21.9 +/- 0.6), fat (2.9 +/- 1.6), carbohydrate (1.4 +/- 0.7), and total ash (1.5 +/- 0.1). Cholesterol, glycogen and total heme pigments (g/kg) in the turkey liver were 2.05 +/- 0.06, 5.36 +/- 0.01 and 2.3 +/- 0.08, respectively. Contents in saturated, monounsaturated and polyunsaturated fatty acids (%) were 42.5, 14.6 and 32.6 respectively. Interestingly, turkey liver fat also contains 5% of camphor (oxygenated monoterpene). Mineral concentrations (mg/kg) in liver were: Na (817 +/- 14), K (1390 +/- 90), Ca (31.4 +/- 0.3), Mg (23 +/- 0.4), Fe (161 +/- 5), Zn (40 +/- 2) and Cu (34 +/- 2). Liver proteins extracted at 5 or 10 g/l NaCl showed the highest foaming capacity (P < 0.05). Addition of xanthan (1-3 g/l) to liver proteins improved both foam formation and its stability (P < 0.05). Turkey liver also showed interesting emulsifying properties. The emulsion stability of liver proteins was more pronounced at high NaCl concentration (20 g/l). The highest emulsion stability was obtained at acidic or basic pH values (P < 0.05) and decreased at pH 6. (C) 2010 The Institution of Chemical Engineers. Published by Elsevier B.V. All rights reserved.