If you’re designing a restaurant there are certain colors to stay away from, and blue is one of them. Blue and purple are associated subconsciously with toxins and spoiled food. Why? Blue foods are not commonly found in nature, with the exception of blueberries and a few other rare foods. Our ancestors regarded blue as a warning color, indicating the food was poisonous.
Sight is the first sense evoked by food. If the color of the food is unappetizing, a food can be immediately rejected. Studies have shown that blue food makes people lose their appetite completely, and in some cases become sick. Just imagine eating a blue steak. Gross! 
Quick sensory design tip: using blue in your menu design or restaurant’s interior may not be such a good idea! Restaurants that use blue in their theme may be more focused on the environment their guests are in than the actual quality of food. Modern Steak, which has a blue logo and blue tables is a trendy place to be seen in Scottsdale, Arizona. It’s reputation for food however, is not stellar. While many reviews focus on the “great ambiance” and “beautiful décor,” few elaborate on the quality of food. A well-known food blogger in Scottsdale wrote a review complete with pictures of Modern Steak. We have included some of his photos in this post, let us know what you think of how the food looks! 
Some diet plans use the reaction to blue to their advantage. Put a blue light in the refrigerator or eating off blue plates.
When was the last time you ate something blue?