My first reaction would be not to think of using a plate heat exchanger because its real advantage is in continuous systems, your batch size is small and its quite expensive.
But more than that it depends on the process and equipment you are using to make your jam at present and what you aims are.
For example are you cooling before you bottle at present? how are you cooling? how are you filling? do you have a cooling/ cooling tower system? what advantage do you see the plate heat exchanger giving?
Maybe you would like to email me to take this a bit further, but my simple answer would be not to use a plate heat exchanger unless there is a very specific advantage it would give your particular business.