Store the bulk of the powder in a dry and airtight container, kept aside so that it is not opened frequently, thereby retaining flavour and freshness. This may be kept in the fridge to safeguard it from insects and pests and will usually stay good for a year. A small quantity for ready use for about a month may be stored in a small tightly closed jar in your regular spice shelf. Always use a dry spoon to take the powder out as moisture and damp can spoil the rasam powder.