Translation:My sister has some chocolate crepe recipes.
"des recettes de crêpes": is this descriptive "de"?
"la nourriture des éléphants": is this possessive "de"?
I found it from this site http://french.about.com/od/grammar/a/de-vs-du-de-la-des_4.htm, yet it's still not 100% clear to me.
can I safely say that if it's a non-living being, it'll always be descriptive?
The nuance between possessive and descriptive is that the latter does not require an article:
la nourriture de l'éléphant, le fils de Pierre (no article with names, of course), la poignée de la porte
la recette de crêpes, la feuille de papier, le tas de pierres
If you can use a possessive in English (the elephant's food, Peter's son or the door's handle), the French will be possessive (with article).
If you can use the simple "noun of noun" or "noun noun" in English (sheet of paper, crepe recipe, pile of stones), the French will be "noun of noun" (no article)
The construction is a "noun of noun", where the second noun, without an article, gives further information on the first noun in terms of content, material, quality or purpose.
- une recette de crêpes = a crepe recipe
- une bouteille de lait = a bottle of milk
- une bouteille de verre = a glass bottle