Thermal gelation characteristics of breast and thigh muscles of spent hen and broiler and their surimi.

Spent hen (98 weeks) and broiler (12 weeks) breast and thigh muscles were minced (1 mm orifice diameter) and washed with 0.1% NaCl. A portion of both unwashed and washed mince was mixed with cryoprotectants (CP) at the rate of 4% sucrose, 4% sorbitol, and 0.2% Na-tripolyphosphate to produce surimi and kept frozen at -20°C. The mince and surimi were ground with 3% NaCl and a small amount of water to adjust the final moisture content of 80%. The pastes were stuffed into the sausage casing and heated at 90°C for 15 min to produce gel. The effects of washing, heating and CP on colour composition and thermal gelation properties of hen and broiler minces and surimi were compared. Broiler mince was lighter and less red in colour, higher in protein and lower in moisture, lipid and collagen. Gel strength and breaking strength were higher in spent hen surimi compared to broiler surimi under similar gelation conditions. Gel elasticity, springiness and water retention properties were almost identical in two surimi. Gel quality was markedly deteriorated in spent hen surimi but not so in broiler surimi after 8 weeks frozen-storage. Although CP increased the gel strength of fresh surimi (non-frozen, 0 week storage) from both hen and broiler, they were more effective in broiler surimi than hen surimi in protecting the functional quality of gel.