Its a juice concentration process that I never used or seen before. It defies my previous knowledge in which concentration procedure involves the boiling of liquid to evaporate water off. A method popular at home level up to big industries. I only use it occasionally as I am not a fan. The heat degrades many valuable nutrients.
This other process involves the reverse. Instead of heating, the juice is frozen. It kinda have a preservation effect on nutrients and flavors.
The procedure below is what I used for a client. She wanted concentrated juice out of her harvested dalandan oranges. Something that she easily do in home and at the same time, if possible, preserve nutrients.
1) Extract the juice by whatever method appropriate and convenient. Take care not to break any seed. Broken seeds imparts bitter taste. There are ways to remove this nasty flavor in case, but prevention is better and much much cheaper.
2) Transfer juice to ice bags. Place inside freezer until completely frozen.
3. Remove frozen juice pp bags. Place on strainer over a clean container. Allow it to melt slowly at room temperature. Do not use fan or additional heat. Too fast ice melting is not desirable.
4) Start collecting melted juice after 15 minutes and repeat every 15 minutes. Stop when ice is faded and the dripping juice is lighter.
In the process. Juice particles melts faster than water. The procedure maybe repeated several times if a more concentrated product is desired.
Store the darker colored juice for later use. Use the lighter ones as soon as possible.
The process never uses heat and preservative. Store it inside refrigerator.