No matter how unbelievable it may sound, the colors blue and purple have been associated with toxins and thus decrease the appetite of customers. Whether or not this statement is true, the fact is that there aren’t many naturally occurring blue or purple food items which are why they are considered to limit the appetite a person has. Blue is generally linked with relaxation. So if you own a coffee house where you want people to have a relaxing time and enjoy their beverages, blue and purple should be your restaurant interior colors.

Cafe Coffee Day makes abundant use of the color purple and is one of the most popular coffee destinations in the country. But do not forget that they do so with a contrast of red which is almost at the opposite end of the color wheel. While purple and brown wood typically saw in a ‘Cafe Coffee Day’ create the aura, the red logo gives it fast-casual dining feel and encourages impulsive buying. Also, red catches the customer’s eye far before purple, so the decision to spend is already cultivated before the relaxing mood kicks in.

Source: https://www.posist.com/restaurant-times/restro-gyaan/know-restaurant-interior-colors-can-affect-sales.html