Plan de Conciliación en la empresa: fases

Imitation cheeses or analogues are cheese-like products that are made by blending together a number of individual components to make a cohesive cheese-like mass (Bachmann, 2001; Noronha, O’Riordan, & O’Sullivan, 2008). The use of imitation cheese blend products allows manufacturers to manipulate individual components to influence texture, nutrition as well as potential economic benefits (Bachmann, 2001; Pereira, Bennett, McMath, & Luckman, 2002). The processing parameters used in the manufacture of these cheese products can also be manipulated to achieve desirable functional properties (Noronha, Duggan, Ziegler, O'Riordan, & O'Sullivan, 2008). Imitation cheeses, as well as providing a product that can be made to meet particular customer requirements (Noronha, O’Riordan, et al., 2008), also provide an ideal system for analysing the effects of different factors on the cheese product. These cheeses are labelled as ‘imitation’, ‘analogue’, ‘artificial’, ‘substitute’, ‘filler’, ‘extruded’ or ‘synthetic’ (Muir, Tamime, Shenana, & Dawood, 1999).

Imitation Mozzarella or Pizza cheese analogues (PCA) (Sherkat & Walker, 2002) are terms used to describe the wide range of cheese products used as alternative pizza topping to traditional Mozzarella. Imitation or analogue Mozzarella has become of increasing importance due to the demand for convenience foods, such as pizzas, as well as the desire for manufacturers to reduce costs (Ennis, O'Sullivan, & Mulvihill, 1998; Sherkat & Walker, 2002). These pizza cheese analogues are one of the biggest uses of functional caseins (Fox & Kelly, 2004).

The majority of casein-based imitation cheeses have been specifically manufactured for use on frozen pizzas and have thus been manipulated so that the textural and melt properties meet the requirements for this use (Noronha, O’Riordan, et al., 2008). The use of rennet casein in the manufacture of imitation and processed cheese is common practice as it produces products with a ridged structure that also have good melting and

41

stretching properties (Aimutis, 1995). Rennet casein is insoluble in water so in order to hydrate it calcium chelating salts are added to disrupt the calcium mediated cross bridges between the casein (Ennis et al., 1998). This gives the proteins a greater degree of mobility and freedom which enhances the casein to form networks, increasing the viscosity of the dispersion. These cheese analogues produced with rennet casein need to be manufactured so that the hydration properties of the casein remain constant through its shelf life (O'Sullivan & Mulvihill, 2001). The paracasein derived from solubilising rennet casein is desirable in the manufacture of imitation Mozzarella as it produces a product with good functional properties (Aimutis, 1995). These properties can be controlled by the manufacturer by varying the composition of the product. To adjust the stretching properties of the imitation Mozzarella the sodium to calcium ratio can be changed.

Although these cheeses are made in alternative ways to traditional Mozzarella, these cheeses are commonly referred to as Mozzarella and are becoming increasingly more common.

2.3.1 Model Systems

It is difficult to use real cheese to investigate the relationship between composition and texture due to a number of factors (Marshall, 1990). One of the main reasons is that natural cheeses are not homogeneous or isotropic and therefore their rheological behaviour is nonlinear outside specific limits (Tunick, 2000). Thus model systems using cheese analogues offer a convenient medium to investigate these relationships. Cheese analogues provide a good model system for research purposes due to the composition uniformity that can be obtained over time and different batches (Pereira, Bennett, Hemar, & Campanella, 2001). Another reason as to why model systems are advantageous to work with over real cheese is that they generally have more simplistic processing requirements (Watkinson et al., 2001).

42

Previous uses of model systems include the development of a system to determine the effect of varying the amount of colloidal calcium phosphate on the rheological properties of Cheddar cheese (O'Mahony, McSweeney, & Lucey, 2006). The effect of different caseins on microstructure and meltability has been investigated using a model processed cheese system (Savello, Ernstrom, & Kalab, 1989).

The protein within the cheese analogue structure reduces the surface tension at the oil and water interface, which increases the stability of the emulsion (Ennis & Mulvihill, 1999; Shimp, 1985). If a dry protein is used in the model system it needs to be properly hydrated in order to perform this function properly (Ennis & Mulvihill, 1999). The majority of cheese analogues are manufactured using rennet casein (Guinee, 2002a). The hydration of rennet casein requires the addition of calcium-sequestering salts to disrupt calcium mediated cross-bridges amongst the proteins (Aimutis, 1995; Ennis & Mulvihill, 1999).

Mozzarella/pizza cheese analogues have been used as model systems to investigate the effects of altering the composition and processing parameters on the functional properties of the product (Ennis & Mulvihill, 1999; O'Sullivan & Mulvihill, 2001; Sherkat & Walker, 2002).The majority of Mozzarella analogues use rennet casein as a protein source due to its ability to give a product with good melting and stretching properties (Aimutis, 1995). Sherkat & Walker (2002) found that the aging of the analogue cheese was not necessary due to bacteria and natural milk enzymes not being present in the product. However, they did find that the product did benefit from a short storage time. Work has also been done on the effect of rennet casein used in Mozzarella analogues (Ennis & Mulvihill, 1999; Ennis et al., 1998; O'Sullivan & Mulvihill, 2001). This work has looked at effect of hydration (Ennis et al., 1998), effect of different types of rennet casein (Ennis & Mulvihill, 1999) as well as the physio-chemical characteristics of the rennet casein (O'Sullivan & Mulvihill, 2001) in Mozzarella analogues.

43