Baroness Crawley said in one recent analysis of food samples, a third had been adulterated with other substances. Her warning comes in the light of the horsemeat scandal last year.
The Labour peer called on the Government at Question Time in the Lords to recognise the "serious" level of the "food adulteration crisis".
She said: "Reporting of food fraud has increased 66% since 2009, while the number of samples taken by local authorities has decreased 26%.
"Call me old-fashioned but I like my ham to actually be ham, not poultry died pink or meat emulsion, whatever that is. I want fruit juice to be just that and not laced with vegetable oil that is used in flame retardants.
"Of the 900 samples tested by West Yorkshire Trading Standards, a third were not what they were meant to be."
Lady Crawley said Professor Chris Elliott's first report into how to protect the safety and authenticity of food following the horsemeat scandal had been "highly critical of the current system's ability to tackle food crime".
She said: "What is the Government doing about the depletion of trading standards departments across the country whose job it is to track down organised criminal gangs in the food sector?"
Food Minister Lord de Mauley said the Government took the threat of food fraud "very seriously".
"Following the horsemeat fraud last year, we have been working with industry and local authorities to improve our intelligence sharing to target sampling and enforcement better," he said.
"The sample carried out by the West Yorkshire Trading Standards demonstrates the action being taken by local authorities across the UK to tackle known problem areas and in response to complaints. The findings are not representative of all food products."