Starbucks is set to unveil a new line of baked goods that will include yoghurt muffins, loaf cakes and even spinach croissants.

The coffee giant is hoping to expand its range of food items, which are purchased by one in three customers and generates around $1.5 billion a year in revenue.

Nine stores in San Francisco will trial the products with a view to rolling them out nationally, although there is no time frame for this as yet.

Among the items being tested are a whole wheat spinach croissant, a tomato, cheese and herb croissant, a blueberry yoghurt muffin and a raspberry passion fruit loaf cake.

Many of them will be served warm, unlike its current line-up of baked goods.

The move comes after the Seattle-based company bought small San Francisco bakery chain La Boulange in a $100 million deal in the summer.

At the time, Starbucks said it hoped to use items produced by La Boulange to popularize the French bakery experience in the U.S. like it had done with the Italian espresso.

The deal could also strengthen the firm’s position in a fast-growing segment of the restaurant industry dominated by Panera Bread Co, which offers baked goods in a seated setting.

Its current range of bagels, breakfast sandwiches and oatmeal will not be affected by the changes, it was reported by The Huffington Post.

Lisa Passe, a spokeswoman for Starbucks, said they would be handling the expansion “week by week, figuring it out”.

Other items on trial from La Boulange, which has 19 locations in the Bay Area, include a chocolate chip cookie, an almond cookie and vanilla shortbread cookie.

Starbucks says it plans to expand La Boulange into a national presence in coming years.

Earlier this year, Starbucks announced plans to attract evening trade by offering beer and wine on its menus.

The company said it planned to bring the new items to a few Chicago-area cafes by the end of 2012 and is also testing wine and beer sales in Spain.

But it did not expect to sell alcohol in all of its nearly 11,000 U.S. cafes.

Spinach is a health powerhouse.

It offers twice as much fibre as other greens and is an excellent source of beta-carotene, an antioxidant that can reduce the risk of heart disease and cancer.

It also contains lutein, which helps prevent age-related macular degeneration.

Serve raw, spinach is a good source of vitamin C, as well.