Salad dressing more than four months past its best-before date. Infant formula that had expired months before it arrived. These are just some of the customer complaints posted on Amazon's Canadian website about grocery orders that arrived past their prime.

CBC News examined customer reviews for various grocery items posted on Amazon.ca in 2018-19, and discovered numerous complaints about old food. Several customers reported that they had received expired infant formula and dozens more complained that the online retailer had sent food — including mayonnaise, baby food and coconut milk — that was past its best-before date.

Almost all the items were shipped directly from Amazon's warehouses. The company said the problems have been addressed and were the result of isolated technical issues but did not elaborate.

Lana Lukyanava of Richmond Hill, Ont., said she was upset when her order of baby food from Amazon.ca arrived on July 22 — with a best-before date from several days earlier.

"I was shocked. It's baby food. How can they do that?" Lukyanava said in an interview with CBC News. "Don't they have enough funds to implement quality control?"

A review by an Amazon.ca customer shows protein bars that appear to have a best-before date from close to a year before the order arrived. (Amazon.ca)

Andreea Catana of Calgary said she didn't notice the cookies she bought on Amazon.ca last year were past their best-before date — until she ate one, and it tasted stale.

"That is quite concerning that Amazon would not have somebody check the shelf life of their products before they send them out," she said.

Customers can't check best-before dates before they buy food online. Food safety experts say Amazon needs to do better.

The Seattle-based online retail giant began selling and shipping groceries to Canadians in 2013.

Keith Warriner, a microbiologist at the University of Guelph, said selling expired infant formula is concerning because it means the product may have lost some of its nutrients. (CBC)

"They've got a corporate responsibility to ensure that people get a good product," said Keith Warriner, a microbiologist at the University of Guelph.

He said selling expired infant formula is concerning because it means the product may have lost some of its nutrients.

"You basically could be giving your baby food that's deficient," he said.

Unlike infant formula, which has an expiration date, most foods come with only a best-before date, which guarantees food quality and freshness. While stale food typically doesn't pose a health threat, food safety expert Rick Holley said it's still bad business to ship it to customers.

"Your expectation is that it's good quality," said Holley, a University of Manitoba professor emeritus. "If I want to buy [lesser]-quality food, I'll go to that section of the grocery store, and I'll be able to buy it at a discount."

'Top priority' to provide 'high-quality' items, Amazon says

Amazon said that it's committed to selling customers quality food.

"Our top priority is ensuring customers receive safe, high-quality products when they order from our store," the company said in an emailed statement.

"We have proactive processes in place to ensure customers receive products with sufficient shelf life and use a combination of artificial intelligence and manual systems to monitor for product quality and safety concerns."

Amazon also said that its customer service teams can immediately stop selling an item if they become aware of quality concerns.

A review on Amazon.ca shows a package of cookies that the customer said was past its best-before date when it arrived. (Amazon.ca)

If customers do happen to receive aged food, Amazon said, they can get a refund.

However, CBC News pointed out that the company's Canadian website states that grocery items are non-returnable, giving some customers the impression that they can't get their money back under any circumstances.

Shortly after CBC News's inquiry, Amazon added a line to its returns policy page that grocery items can be "refunded or replaced."

Lukyanava didn't try to return her baby food because it was inexpensive. Instead, she posted a review about her experience but said she never got a response.

"I was hoping that it would cause some reaction, but there was nothing," she said. "I felt really disappointed."

CBC News asked Amazon about Lukyanava's case. A few days later, the company emailed her to apologize for her experience and inform her she's getting a refund for her $6 purchase.

Other retailers get complaints

Amazon.ca isn't the first retailer to face complaints about selling old food. In 2015, CBC's Marketplace interviewed employees at a number of grocery stores who claimed that their stores used tricks to make food appear fresh and changed best-before dates to extend their shelf life.

Amazon's U.S. site has also faced accusations that some of the third-party merchants on its site are selling old food.

U.S. data analytics firm 3PM Solutions recently analyzed Amazon.com's 100 bestselling food products for CNBC. The firm found that at least 40 per cent of third-party sellers had more than five customer complaints about goods that had expired or were past their best-before date.

"Seeing that 40 per cent of these sellers had multiple mentions of selling expired product was disappointing," 3PM CEO Rob Dunkel said in an interview with CBC News. "It's really the consumer who's really getting hurt here."

Amazon told CBC News that it screens all its selling partners and that they must abide by product quality guidelines. The company said it takes appropriate action when dealers don't play by the rules.