He said he shared them "because I wanted to let people know what they're consuming, and how disgusting the conditions are."
Soon after posting the gag-inducing photos, Nick says he was fired without being given an explicit reason.
He claimed that McDonald's representatives approached him and demanded that he take the photos down as they were damaging the company brand.
Twitter users have had mixed reactions to the shocking images, with some sharing similar experiences from working at McDonald's.
However, some have labelled Nick and his co-workers "lazy", saying it is the employees' job to make sure the machines are clean and sanitary.
Nick and other McDonald's workers hit back saying that they were never taught or asked to clean the machines, and that this was the store manager's job.
Nick also urged those following his tweets to "watch What the Health on Netflix", commenting on an image of frozen beef patties: "Y'all say y'all don't care about this bc y'all don't love yourselves or your bodies. I care about what I eat and this doesn't cut it."
Not everyone was buying his message, with one Twitter user replying sarcastically: "We should bow down to this god among men and thank him endlessly for the sacrifices he endured to show us what frozen food looks like."
Nick said he posted the images only after he had found a new job, which he starts soon.
News.com.au asked Nick about the intentions behind his posting the images, and where his new job was.
He declined to reveal further details or whether he would continue working in the fast food industry.
"I'm not a vegan activist," he said. "I just watched the Netflix show and it made me not want to eat meat or dairy, even though I still do."
LaPlace McDonald's owner and operator John Valluzzo told BuzzFeed in a statement that his restaurant "regularly conduct[s] in-person and online employee training sessions as well as internal inspections to ensure crew members are following safe food practices."
"In addition, we have a long history of passing regular health department inspections," Valluzzo said.
A spokeswoman for McDonald's Australia said in a statement that the tray pictured was designed to catch any leaks from the equipment seals which protect other parts of the machine.
"This part does not come into contact with the ice cream served and is required to undergo regular and timely cleaning," the spokeswoman said.
"We are committed to running great restaurants that provide our customers with high quality food, service and a clean environment."
