Provided is a technique of extracting a component in a food from the food by using a reducing agent that is inexpensive and has a mild reducing action. A component in a food is extracted by mixing the foodwith an extractant containing a sulfite. In addition, the resultant food extract is brought into contact with a specific antibody that specifically recognizes a substance included in a specified ingredient of interest for inspection, to thereby inspect the presence or absence and/or the amount of a specified ingredient in a food by utilizing an immunological measurement method. Further provided is a food inspection kit for inspection of the presence or absence and/or the amount of a specified ingredient in a food, including: (1) an extractant and a sulfite to be added to the extractant, or an extractant including a sulfite added； and (2) an antibody that specifically recognizes a substance included in a specified ingredient of interest for inspection.
