It is intended to provide a technique for extracting a food component from a foodby using a reducing agent which is inexpensive and has a mild reducing effect. A component in a food is extracted by mixing the food with an extractant containinga sulfite. The food extract thus obtained is brought into contact with a specificantibody capable of specifically recognizing a substance contained in a specificstarting material to be inspected. Then, the presence or absence of the specificstarting material and/or the amount thereof in the food is determined by usingan immunoassay method. Further, it is intended to provide a food inspectionkit for determining the presence or absence of a specific starting material and/orthe amount thereof in a food which comprises: (1) an extractant and a sulfite tobe added to the extractant, or an extractant containing a sulfite, and (2) an antibodycapable of specifically recognizing a substance contained in a specific startingmaterial to be inspected.
