Water sublimation stops at -80c, 193 kelvin. Flash freezing followed by long term storage in liquid nitrogen should be sufficient for preserving quality indefin

Water sublimation stops at -80c, 193 kelvin. Flash freezing followed by long term storage in liquid nitrogen should be sufficient for preserving quality indefinitely. More practically, while sublimation hurts "quality", it does not harm the nutritional value of the food, so does not seem like that big of a deal in the context of famine policy. For rice it is even less of an issue, because rice is routinly stored dry and rehydrated when cooked.