Influence of Immersion Freezing in NaCl Solutions and of Frozen Storage on the Viscoelastic Behavior of Mozzarella Cheese

Abstract

The freezing of Mozzarella cheese by immersion in NaCl solutions may be an innovative procedure for the dairy industry because it combines conveniently salting and freezing processes. In this work, the influence of this type of freezing method and of the frozen storage of samples on the viscoelastic behavior of Mozzarella cheese was studied. Slabs (2 x 10 x 10 cm(3)) were immersed in 23% w/w NaCl solutions (control samples: 4 degrees C, 90 min; frozen samples: -15 degrees C, 180 min). Half of the frozen samples were immediately thawed at 4 degrees C . The other half was stored at -20 degrees C for 2 mo and then was thawed at 4 degrees C (frozen-stored samples). Samples were stored at 4 degrees C and assayed at 1, 7, 14, 20, 27, 34, and 41 d. Rheological tests were carried out in oscillatory mode (parallel-plate geometry, diameter: 20 mm, gap: 1 mm, frequency: 1 Hz). Strain sweeps were run (0.001 </=gamma(0)</= 0.1) at 20, 40, and 60 degrees C, and temperature sweeps were run from 20 to 65 degrees C (1.33 degrees C/min, gamma(0)= 0.005). Similar crossover temperatures were observed after 20 d of ripening. The influence of temperature on complex viscosity was studied by an Arrhenius-type equation. Activation energy values of 15.9 +/- 0.4, 14.1 +/- 0.5, and 13.8 +/- 0.6 kcal/mol were obtained at 41 d for control, frozen, and frozen-stored samples, respectively. Although the immersion freezing of Mozzarella cheese affects some of the studied parameters, the differences observed between frozen and frozen-stored samples with control samples were small. Therefore, it was considered that the immersion freezing might be useful for the manufacture and commercialization of Mozzarella cheese.

Effect of freezing on the viscoelastic behaviour during the ripening of a commercial low-fat soft cheese

“…This result indicates that the freezing process did not produce modifications in the extent of the linear viscoelastic region of the LFSC. Similar behaviour was observed by Ribero, Zorrilla, and Rubiolo (2007), who have studied the influence of immersion freezing in NaCl solutions and of frozen storage on the viscoelastic behaviour of mozzarella cheese. The authors published that a critical strain of 0.005 at 1 Hz was obtained from strain sweeps for both refrigerated and frozen samples, indicating that freezing process did not produce modifications in the extent of the linear viscoelastic region of Mozzarella cheese.…”

Microstructure of Mozzarella cheese as affected by the immersion freezing in NaCl solutions and by the frozen storage

“…In addition to the advantages associated with a fast freezing method, immersion freezing of cheeses would allow decreasing the production time because salting and freezing occur at the same time. Ribero et al (2007) shown that although the immersion freezing of Mozzarella cheese affects some of the studied viscoelastic parameters, the differences observed between frozen and frozen-stored samples with control samples were small. Microstructural studies may contribute to a better understanding of the effect of this new freezing alternative on Mozzarella cheese characteristics.…”

“…The crossover temperature can be used to identify the solid-like to liquid-like phase transitions the cheese undergoes during melting (Gunasekaran and Ak, 2003). Ribero et al (2007) observed that crossover temperature decreases as ripening time increases. Moreover, at ripening time higher than 20 days, crossover temperatures were similar for the three treatments studied.…”

“…Particularly, Ustunol et al (1994), Zhou and Mulvaney (1998), Lucey et al (2003), Montesinos-Herrero et al (2006) related some viscoelastic parameters to some functional properties. Ribero et al (2007) showed that the viscoelastic parameters affected by the treatments studied (control, immersion freezing, and immersion freezing plus frozen storage) were the crossover temperature (the temperature at crossover modulus during temperature sweeps) and the activation energy (resulting parameter when the influence of temperature on complex viscosity is studied by an Arrhenius-type equation). The crossover temperature can be used to identify the solid-like to liquid-like phase transitions the cheese undergoes during melting (Gunasekaran and Ak, 2003).…”

“…An interesting alternative for fast freezing of cheeses may be freezing by immersion in NaCl solutions (Zorrilla and Rubiolo, 2005a,b;Ribero et al, 2007). In addition to the advantages associated with a fast freezing method, immersion freezing of cheeses would allow decreasing the production time because salting and freezing occur at the same time.…”