Yes, you can (and actually should) say Navkar Mantra before eating food.

In Jain tradition, it is considered very good practice to:

• Remember Arihant, Siddha, Acharya, Upadhyay and all Sadhus through Navkar Mantra
• Then start drinking water or eating food with shanti and gratitude

Many Jains even take a small resolve like: “I will not take water or food without reciting Navkar Mantra.”

So saying Navkar Mantra before food is:

• Allowed
• Recommended
• Spiritually beneficial (it brings awareness, reduces attachment, and creates punya)

Just try to say it with concentration, not in a hurry, and then start your meal calmly.