Today marks the last day of full production at Kellogg's breakfast cereal factory in London, Ont.

The last day of scheduled work in the plant is Dec. 23.

The company has been in London for 100 years. The plant closing this month is 75 years old. It has made more than 20 different products and packaged them all in-house.

Bob Martin is president of Local 154G of the Bakery, Confectionary, Tobacco Workers and Grain Millers union, which represents the workers there. He said the plant is closing because cereal sales are down.

"It's kind of a fast-paced world that we're living in anymore," he said. "It's not as common to sit at the breakfast table and pull out that box of cereal as it was when I was a child.

"You read the back of the cereal box Monday and you read it again Tuesday and Wednesday."

According to research firm NPD Group Inc., the average person has just 12 minutes a day to eat breakfast, compared with 28 minutes for lunch or 24 minutes for dinner.

Pressed for time, consumers are springing for the cheap breakfast sandwich to go at McDonald's or Tim Hortons. Breakfast now accounts for 12 per cent of America's restaurant industry, adding up to a $42-billion US business every year.

In August, Kellogg, the world’s top cereal maker, reported a 16 per cent drop in profits.

In the U.S., overall cereal sales have fallen about two to three per cent per year since 2010. Instead, more people are stocking their fridges and cupboards with protein-packed Greek yogurt, eggs and fibre-heavy oatmeal.

Kellogg warned in 2013 it would cut its global workforce by seven per cent.

The London factory is at 100 Kellogg Lane, just south of Dundas Street.

"When you drive down Dundas Street and you get the aroma of whatever we're producing that day, it feels like home," Martin said. "Knowing that plant is gone, is really kind of hard to put into words. It's the end of an era for London."

The plant's closure puts 500 people out of work — more than 300 lost their jobs in September. A job action centre has been established for employees.

"The hope is to find anyone inquiring meaningful work," Martin said.

The Kellogg plant is the second major food processor to close up shop in southwestern Ontario this year. Heinz ceased operations in Leamington in June. Nearly 1,000 people lost their jobs there.

A Canadian startup did come in and begin processing some food for Heinz, giving work to 200 people.

It's not yet known if there is similar interest in the London Kellogg plant.

"The building is still viable. The plant is still viable," Martin said. "As of today, we haven't been told of any solid future for the plant."

With files from Meredith Healey, CBC News