Effect of pH and time on the quantity of readily available water within fresh cheese curd

Abstract

Some of the textural changes that occur early in cheese maturation may be related to the redistribution of water within the cheese matrix. To examine this, a model cheese curd system was devised and explored. Initially, cheese curd was prepared using starter and chymosin and the curd pH was controlled by varying the draining and salting pH values. The quantity of serum that could be centrifuged from the resultant curd was less for lower pH curd and decreased in volume with time. The curd pH decreased with time. In the protocol finally adopted, milk was acidified with lactic acid and coagulated with Rennilase 46L. After cheddaring, salting and light pressing, the samples of this curd were finely diced and mixed with glucono-δ-lactone to give curd samples with comparable moisture contents, similar casein proteolysis rates but different pH values. The quantity of serum that could be centrifuged from these samples was greater for pH 5·6 curd than for pH 5·2 curd and decreased faster for the lower pH curd. Neither the curd moisture nor the pH changed significantly during curd storage and the casein proteolysis was low. These results for the model curd system are consistent with known water absorption characteristics of casein curd under ‘equilibrium’ conditions and the effects of pH and mineral salts on this absorption. It was concluded that, during the early stages of cheese ripening, there may be a redistribution of moisture within the cheese, related to the basic properties of the protein matrix and the transient effects of curd salting, rather than as a direct consequence of glycolytic and proteolytic changes.

Evaluation of the melting capacity of Prato cheese obtained by modifications of the traditional manufacturing process

“…4). Ramkumar et al [39] observed that the amount of whey centrifuged from a model Cheddar cheese decreased with increase in pH of the curd, suggesting that the capacity of the curd to physically retain water molecules, like the casein-moisture interactions in the cheese, were pH-sensitive. Kindstedt et al [23], working with Mozzarella cheese, also reported that the pH strongly affected the protein-moisture interactions and consequently the melting of the cheese, the cheeses losing their melting capacity at pH values below 5.0.…”

“…During storage, a decrease in expressible water of the cheese usually occurs (water whose mobility is not impeded by the macro-structure of the protein matrix and which can be expressed by centrifugation), such water being found together with the fat and the starter organisms in vacuoles and elongated pockets [33,39]. According to McMahon et al [33], after salting of the cheese, reorganization of the protein matrix possibly occurs, with subsequent absorption of water by these vacuoles/pockets during refrigerated storage.…”

Manipulation of Dhaka cheese curd and effects on cheese quality

“…Hardness decreased significantly (P < 0.001) with the progress of manipulation showing less solid-like behaviour as described by Ramkumar et al (1997). The highest firmness was observed in cheese made with curd without manipulation, while at the end of the third minute, the curd was very soft and the resulting cheese also showed the lowest hardness.…”

“…Results of TPA parameters of cheese are shown in Table 2. Hardness decreased significantly ( P < 0.001) with the progress of manipulation showing less solid‐like behaviour as described by Ramkumar et al. (1997).…”

Equilibrium Between the Protein Matrix and the Serum Phase of Prato Cheese

“…Similar results were observed for several other cheese varieties, such as mozzarella (Guo et al . 1997; Ramkumar et al . 1997; Kindstedt and Guo 1998; Paulson et al .…”