It seems no progress has been made in sterilizing and preserving food for hundreds of years. Thousands with cooking. I think in 100 years' time people will look back at us and wonder why we only, mainly, ate hot or cold food. Can't we 'zap' it somehow? When I'm out and about and want to eat a sandwich, it is always cold. I don't want cold sandwiches. Or a burger - it is always hot.