**11.7 Stepwise freezing method**

In this method, the temperature is lowered to about −30 °C for at least a period of 30 minutes and then abrupt cooling is done via using liquid nitrogen at the much lower temperature of −196 °C. Slow freezing increases dehydration while abrupt freezing promotes crystal formation. It gives excellent results in the preservation of strawberries in the suspension culture.

## **11.8 Storage**

Storing at the correct temperature is as important as that of freezing. For storage, the temperature is left to almost −70 °C to 197 °C because this temperature is sufficiently low for the preservation of cells without metabolic damage to them. Long term storage is mostly done at about −197 °C.
