Hampton Creek Foods Inc., a San Francisco based food startup, has been slapped with a warning letter from the US Food and Drug Administration which says the company cannot call their vegan 'eggless' mayonnaise, "Just Mayo."

According to Time magazine, FDA criteria states that a product labelled as Mayonnaise must contain at least 65% vegetable oil and consist of one or more 'egg yolk-containing' ingredients.

On Tuesday, the FDA published this letter on its official website which explains the reasoning for the decision:

"The name "Just Mayo" and an image of an egg are prominently featured on the labels for these products. The term "mayo" has long been used and understood as shorthand or slang for mayonnaise. The use of the term "mayo" in the product names and the image of an egg may be misleading to consumers because it may lead them to believe that the products are the standardized food, mayonnaise, which must contain eggs as described under 21 CFR 169.140(c)."

The letter also says that the product in question contains other ingredients that do not fall under the conditions for Mayonnaise. Ingredients such as modified food starch, pea protein, and beta-carotene,which may have been used to impart color simulating egg yolk, were also found in the Hampton Creek's eggless mayo. According to the FDA guidelines the presence of these disqualify the item from consideration as mayonnaise.

The FDA also took issue with Hampton Creek's use of the term 'Cholesterol Free.' Hampton Creek's website labels its Mayo as well as it's Sriacha hot sauce products as cholesterol free. The brand also uses the tagline "you'll never find cholesterol in our products" which the FDA feels is synonym for 'cholesterol free'. 

To read more about the ruling check out the FDA's official website.