Black winter truffles are best used within a day or two of harvest when they are fresh and are at their most fragrant. However, they can be stored up to two weeks if done so properly.
Truffles need to breath to prevent rotting. We find that wrapping them individually in paper towels and then placing them in a cardboard box in the fridge is best. You will find the paper towels become damp so it is best to change the paper towels daily. We do have a fridge specifically designated for truffles as the smell can be very over powering and flavor many foods in your fridge so this is why you will often find your truffle in an air tight glass jar. Again it is stressed to change the paper towel frequently if this is the case.
It is common to see truffles stored with rice but this is not actually a good way to keep them. The rice will draw out the moisture from the truffle and they may dry out faster. It is also believed that the rice infuses with truffle flavor, it will smell like truffle, but once you cook the rice you will find that the aroma (as well as taste) will have disappeared.
However, you can infuse other ingredients in your fridge. One common favorite is eggs. Simply place the truffles and eggs (still in their shells and uncooked) together for a few days (even a few hours and there will be a slight truffle taste) and the eggs will absorb the intense truffle fragrance ready for making your favorite egg dish.