Owners of a Concord-based bakery and cafe think all you need is love to make a product taste great — plus a few other key ingredients for flavor, of course.

But the US Food and Drug Administration last month made clear that the federal agency believes otherwise.

In a warning letter issued to wholesale bread and pastry business Nashoba Brook Bakery that was published online this week, the FDA told the owners that listing affection as an ingredient in its Nashoba Granola product is a violation of the rules.

“Your Nashoba Granola label lists ingredient ‘Love,’ ’’ the FDA said in its letter, which was dated Sept. 22. “Ingredients required to be declared on the label or labeling of food must be listed by their common or usual name . . . ‘Love’ is not a common or usual name of an ingredient, and is considered to be intervening material because it is not part of the common or usual name of the ingredient.’’

Law360 first reported on the infraction.

John Gates, the bakery’s chief executive and co-owner, told the Globe that he’s playing ball — “If the FDA says jump, the question for any smart food manufacturer is, ‘OK, how high?’ ’’ — but he found it somehow odd that the feds zeroed in on extracting the love from his granola.

“I have to be a little careful, but it does feel silly,’’ he said. “I get that asking a food manufacturer to take an ingredient off of a label, if the ingredient is not present, makes sense. But in this case, there feels like there needed to be someone who was at the FDA who could look at that and say, ‘Is this really something we want to put in a letter to a business?’ ’’

The granola is sold at the company’s cafe, as well as to a few select food businesses. Ingredients listed before “love’’ include whole wheat flour, oats, almonds, honey, brown sugar, cinnamon, and vanilla, Gates said.

“We often have had people say to us, ‘What makes that granola so good?’ ’’ Gates said. “And it’s kind of easy for us to say that there’s this extra ingredient, called love.’’

Nashoba Brook Bakery opened its doors in Concord in 1998, in an old warehouse, according to the company’s website. Gates said its “core identity’’ is making old-world, artisanal breads that are distributed to gourmet markets, sandwich shops, caterers, restaurants, and supermarkets. The company is also renowned for its quaint cafe in the historic town outside Boston, which has a living-room-like aesthetic.

The warning about the granola came after a series of inspections the FDA made at the bakery’s “ready-to-eat manufacturing facility’’ in Concord between May and June.

Besides discovering that the bakery had mislabeled its granola by adding “love’’ to its food, the agency said it also found “serious violations of the Current Good Manufacturing Practice,’’ the letter said.

The bakery was warned to correct a host of what the FDA called “insanitary conditions,’’ including failing to properly store equipment that could attract pests, letting an apparent dough residue build up on some of its containers, and employees not taking necessary precautions when coming into contact with bread dough.

“The information about ‘love’ as a listed ingredient was included, but is not among the agency’s top concerns, and focusing only on that particular violation detracts from the multitude of serious violations reflected in this letter,’’ an agency spokesperson said in a statement to the Globe. “The agency expects the company to correct the serious violations.’’

Gates said the company will fully comply with the FDA and has already addressed all of the health code violations outlined in the agency’s letter. He said the bakery plans to formally reply this week and pointed out that his workers go to great lengths to make sure the establishment is always properly cleaned.

In its response, Gates said, the bakery will also ask for a little wiggle room when it comes to adding a dash of love.

“On the question of love, we will be asking for consideration that we be allowed to do that again in the future,’’ he said. “It’s meant to be lighthearted . . . and signal to our customers, thank you, we care about what we are giving you, and we will hope you come back, and let’s share the love.’’

Steve Annear can be reached at steve.annear@globe.com. Follow him on Twitter @steveannear.