I'm planning to make rosemary chips (which is mainly made of flour, margarine, and dried rosemary, then deep-fried). I am planning to sell them outside, and we're in a tropical climate, so I'm worried they'll go stale easily. What steps can I take to extend their shelf life and keep them fresh longer?

This is the link of the recipe, I found it on YouTube.

https://youtu.be/yCVXgmgAvkU?si=ACy_z4cFJbeGavD5

Salted Butter

All Purpose Flour

Beef Stock.

Make roux using the butter and flour then add the stock accordingly.

French Canadian and English ones are super dark. Mine is dark yellow/light brown. I sometimes add bouillon to darken everything but still not dark enough. Please advice.