Chemistry Reference
In-Depth Information
9.7.8.
Cheese Texture and Functionality
The importance of calcium and phosphate interactions for cheese man-
ufacturing properties, as well as the textural properties, has been reviewed
(Lucey and Fox, 1993; McMahon and Oberg, 1998; Lucey et al., 2003;
Johnson and Lucey, 2006). The process cheese industry is based on the use
of citrate or phosphate salts to sequester some of the Ca from the residual
CCP, which solubilizes caseins that can then emulsify fat globules. The acidity
of whey at drainage and rate of acid development are recognized as important
parameters that determine the mineral content, acidity and quality of cheese.
Schulz (1952) developed a classification of cheese varieties based on their Ca
contents. Monib (1962) was one of the first investigators to study the Ca
phosphate-casein complex in cheese and he concluded that very dilute cheese
extracts did not represent cheese-like conditions and their use would lead to
incorrect conclusions about serum Ca concentrations (i.e. excessive dilution
resulted in the dissolution of more insoluble Ca). By the 1980s, it was
recognized that acid development during manufacture determines the loss
of Ca, which determines the basic structure of cheese (e.g. Lawrence et al.,
1983). By the early 1990s, there was the realization that much of the residual
Ca in cheese is associated with casein and that much of the CCP was not
dissolved during cheesemaking (Lucey and Fox, 1993). It was also recognized
that the residual insoluble Ca component is an important structural unit
influencing cheese texture (Lucey and Fox, 1993). Many studies have demon-
strated the importance of pH and Ca content on the functional properties of
cheese (e.g. Yun et al., 1993; McMahon and Oberg, 1998; Guinee et al., 2002;
Joshi et al., 2002). It is now accepted that during ripening there are important
changes in the amount of insoluble Ca (e.g. Guo and Kindstedt, 1995; Hassan
et al., 2004) and that these shifts in the Ca equilibrium contribute to textural
changes during ripening (Lucey et al., 2005; O'Mahony et al., 2005). The
proportion of insoluble Ca in cheese has been estimated by the expression of
some of the aqueous phase (''juice'') under high hydraulic pressure (Morris et
al., 1988; Lucey and Fox, 1993), centrifugation to extract some expressible
serum in young, high-moisture cheeses (Guo and Kindstedt, 1995), acid-base
buffering (Lucey and Fox, 1993; Hassan et al., 2004) and water extraction
methods (Metzger et al., 2001).
9.8.
Other Uses/Applications of Milk Salts
Milk minerals (typical composition:
<
5% protein,
<
9% lactose,
>
70% ash,
25% Ca, 14% phosphorus) are produced by concentrating and drying de-
proteinized delactosed whey. This ingredient is often used for mineral
