Dynamic rheological properties of process cheese: Effect of Ca and P content, residual lactose, salt-to-moisture ratio and cheese temperature

Four treatments of Cheddar cheese with two levels (high and low) of calcium (Ca) and phosphorus (P), and two levels (high and low) of residual lactose were manufactured. Each treatment was subsequently split prior to the salting step of cheese manufacturing process and salted at two levels (high and low) for a total of eight treatments. After two months of ripening, each treatment of Cheddar cheese was used to manufacture process cheese using a twin-screw Blentech process cheese cooker. NFDM, butter oil, trisodium citrate (emulsifying salt), and water were added along with Cheddar cheese for process cheese formulation. All process cheese food formulations were balanced for moisture (43.5%), fat (25%), and salt (2%), respectively. Dynamic rheological characteristics (G' and G'') of process cheese were determined at 1.5Hz frequency and 750 Pa stress level by using a Viscoanalyzer during heating and cooling, temperature ranges from 30C to 70C then back to 30C. High Ca and P content, and high S/M (HHH and HLH) cheeses had the significantly higher elastic (G') and viscous (G '') modulus than other cheeses during heating from 30 degrees C to 70 degrees C, and cooling from 70 degrees C to 30 degrees C. No significant difference was observed among the other process cheeses during heating and cooling. Viscoelastic properties of process cheeses were also determined in terms of transition temperature (where G' = G ''), and tan during heating (30 degrees C to 70 degrees C). Cheeses with high Ca and P, high lactose, and high S/M content had higher transition temperature than low Ca and P, low lactose, and low S/M content process cheeses. Low Ca and P and low S/M content cheeses (LLL, LHH, LHL, HLL) exhibited more viscous characteristics than high Ca and P and high S/M content process cheeses (HHL, HLH, LLH, HHH) during heating from 30 degrees C to 70 degrees C. Low Ca and P, low lactose, low S/M content (LLL) process cheese was observed for highest tan delta values (0.39 to 1.43), whereas high Ca and P, high lactose, high S/M content process (HHH) had the least (0.33 to 1.06) during heating. This study demonstrates that different characteristics of natural cheese used in process cheese manufacturing have significant impact on process cheese rheological and viscoelastic properties.