The milk samples are subjected to two different pasteurization regimes. One sample is heated to 85°C and then held for 15 minutes, after which it is cooled to 45°C. The other sample is heated to 63°C where it is held for 30 minutes, after which it is cooled to 45°C.
The aim of this experiment is to find out the curdling rates of these two samples of milk when rennet and/or yoghurt culture is added.
Sample A was subjected to low temperature long time (LTLT) pasteurization while sample B was subjected to high temperature short time (HTST) pasteurization.
Each of the batches were sampled into separate beakers, their pH measured and recorded.
3 mls of yoghurt culture was added into each beaker followed by 3 mls of activated rennet.
The pH was then determined after every five minute intervals for the next 10 minutes.
Meanwhile, the remaining samples ware inoculated with yoghurt culture and activated rennet and left to curdle.
|Sample||Initial pH||pH on addition of rennet||pH after 5 minutes||pH after 10 minutes|
Upon cutting the curd, sample A formed a thick curd while sample B remained practically curd-less.
From the results obtained in this experiment, it is safe to conclude that milk to be used for cheese-making should be subjected to low temperature long time (LTLT) pasteurization.
This will encourage faster curd formation because low heat does not denature the whey proteins, which are instrumental in the bond formation of the curd.