What are the best methods for preserving and storing frozen egg yolk to maintain its quality and freshness?

The best methods for preserving and storing frozen egg yolk to maintain its quality and freshness include separating the yolks from the whites, adding a pinch of salt or sugar to prevent them from becoming too gelatinous, and storing them in an airtight container or freezer bag. It is also recommended to label the container with the date and use them within 3-6 months for best results.