"It seals them and stops them from going bad, which saves you time and money."
Other mums were quick to praise her advice, with one writing: "I did this with my last jar of tomato paste and got through a whole jar before it went mouldy."
It might seem like it could cause a mess, but experts explained how it actually helps your food last longer.
CSIRO Agriculture and Food senior food microbiology consultant Cathy Moir told the Mail:
"By turning the jar upside down, that surface where a mould may have landed when you opened the jar is now squashed against the lid without much air and it will find it more difficult to grow."
She said it worked best with thick foods like pasta sauce, tomato paste and salsa.
To increase shelf life even further, Moir recommended using a clean spoon each time you dip into the jar, and leaving the lid off for as short a time as possible.