What I have observed is that polythene degrades on long exposure to sun. Nylon ropes too. Glass does not. Jute cultivation and processing is nearly finished in India. Better paying crops are avalable. So, forget about jute carry bags. Cotton bags are made from a relatively inferior fibre, better quality goes for textiles. Both cotton and jute bags are NOT water proof, a very strong criterion. You do not cart along stainless steel vessels on the off chance that you MIGHT bring packaged food. I am a N. Indian. But we do take S. Indian food. Coconut chutney and sambhar are put into polythene bags. Dosa, idly, uttapam etc. can be in paper bags. And all are put into a large, strong carry bag of plastic. Flip side of paper is that it has acids, which easily get into your cooked food. Acid is what turns a paper yellow and makes it crumble. And natural leaf wrappings are not easy to find. But imagine how many banana trees would be needed to satify the demand all over India.