Curd tension

Gel strength (curd tension). The gel network continues to develop for a considerable period after visible coagulation (Figure 10.8). The strength of the gel formed, which is very important from the viewpoints of syneresis (and hence moisture control) and cheese yield, is affected by several factors - the principal ones are summarized in Figure 10.9. 

Figure 10.9 Principal factors that affect the strength of renneted milk gels (curd tension) pH ( ), calcium concentration (O), protein concentration ( ), preheat treatment (x).

Tambat R.V. and Srinivasan, M. R. 1979. Changes in surface tension, viscosity and curd tension of buffalo and cow milk during Cheddar cheese manufacture. Ind J. Dairy Sci. 32, 173-176. 

Richardson, G. H., Gandhi, N. R., Diratia, M. A. and Ernstrom, C. A. 1971. Continuous curd tension measurement during milk coagulation. J. Dairy Sci. 51, 182-186. 

Richardson, G. H., Okigbo, L. M. and Thorpe, J. D. 1983. Continuous measurement of curd tension during cheese manufacture. Proc. 6th Int. Congr. Food Sci. Technol. 2, 148. 

The effects of homogenization on milk components have been summarized by Walstra and Jenness (1984) and Harper (1976). Homogenization disrupts fat globules and results in an increase in fat surface area (about 4-10 times). Casein micelles adsorb on the fat surface and constitute part of the fat globule membrane. The curd tension of milk is thus lowered. Walstra and Jenness (1984) have described the effect of homogenization on rennet coagulation. 

The strength of renneted milk gels (curd tension, CT) is very important, especially from the viewpoint of cheese yield. This subject has been reviewed (Fox, 1984 Green and Grandison, 1993). Suffice it to say here that curd tension is positively affected by protein concentration, [Ca +], and reduced pH to —5.9 and adversely by high heat treatments. Thus, CT is affected by the same variables that affect rennet coagulability. 

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