Goodmorning- The coagulation that happens when you dd the rennet to your milk is a highly complex chemical reaction. Our fellow member Pav has written a few short paragraphs on the Washington cheese Guild website. He state:
"he acidity level of the milk when you adding rennet and the time from adding rennet to the time you cut the curd are two important decision factors in making blue cheese. The acidity level is important because it coincides with the amount of starter added earlier, and the time spent in ripening the milk to activate the starter. Normal milk has a pH of about 6.6. Most blue cheeses are renneted at a pH of 6.4-6.5. If the pH is too high, the rennet is not as effective and the milk takes longer to set. If it is much lower, then the bacteria are active, or too much starter has been used, or the milk is off, or too much time has gone to ripen the milk. A slightly acidified milk also retains moisture better because the acid degrades calcium, making the casein proteins more likely to retain water.
After adding rennet, the next aspect to consider is the strength of the curd when cutting it. This is crucial to obtain the proper final moisture content of the cheese. A strong curd that sets for a long time after adding rennet retains moisture better than a weak curd that has not set for long. It may seem counterintuitive, but the longer a curd sets, the stronger the coagulum gel becomes, and it is less likely to release moisture from within that coagulum.
A good way to determine when to cut, especially without years of experience, is to use a multiplier method in combination with timing the point when the surface gels. Rennet coagulates milk in two phases. The first phase is when the rennin cleaves about 75% of the k-casein protein, which enables the other caseins to bond together. And the second phase is when those proteins actually initially bond and form a weak gel. The transition point happens very quickly, and that's when a surface gel forms. If you measure the amount of time it takes from when you add rennet to when a surface gel forms, it is possible to use a multiplier to determine when to cut the curd. The time it takes for the surface to gel varies with the milk, which itself varies with the lactation period, time of year, feed, etc. By using a method to time the initial surface gel and a multiplier, you can be fairly sure that the coagulum strength is the same regardless of the milk.
To use a multiplier method with the surface gel point, measure the amount of time it takes from when you add rennet to when the surface gels, and then multiply that time by a multiplier. Blues use a 4x multiplier. A useful method to determine the surface gel point is to float a sanitized bowl that floats on top of the milk and nudge it. When you nudge it and it doesn't move, the surface has gelled. This usually takes 10-15 minutes. To determine the point of cutting the curd, multiply the time to surface gel by the multiplier. For example, if it takes 10 minutes for the surface to gel, with a 4x multiplier, you will wait 40 minutes total from the time you added rennet to the time you cut the curd."
This briefly describes the process that you want to follow to determine curd flocculation point-good work once again Pav! As far as a list of multipliers I have attached a very short list you can use as a guideline posted by another member some time ago. Remember that this is another tool that you can use to craft your cheese in the manner(moisture content) that you want and to be able to achieve consistence(reproducibility)in your makes. The multiplier is only a guide..sometimes based on common practice. You might feel that you need to tweak it for your own use. If the make calls for a multiplier of 3, don't be afraid to use 2.5 or 3.5 to fit your needs. You will obviously will not want to double it or cut it in half- you COULD do this if you were looking to make a totally different cheese. For instance if you were making a Romano and used a multiplier of 4 you might end up with a very nice cheese, but the curd would be way too moist and probably would not be very gratable at all. It would probably also age quite a bit faster than a traditional Romano. Lots to consider here...thanks to the members who provided the information I have quoted in this post.
