How to persuade the buyer of supermarket to purchase my product?

Promote your product properly and honestly. Do not promise features that can not be found in your product. Likewise, list the benefits you can get your product and what makes your product different from its competitors.
 
Running promotions
 
In addition, you can also do some promotion of its products. If a food can have a free tasting for buyers. Otherwise, you can set up promotions such as buy one gets one free item or one that comes with its main product, if you can afford. Buyers love the discounts and promotions.
 
Consider this
 
Make sure you stay true to their sales and promotion of speech, otherwise, your product's reputation is at stake.