Identification and characterisation of food proteins are core features of food allergy research. Current methods used to identify allergenic proteins in food have insufficient resolution and are unable to detect low molecular weight proteins. In this study we report the use of a simple SDS-PAGE method which allows resolution of small proteins. We have subsequently applied this method and reported presence of low molecular weight proteins in a range of hydrolysed milk formulae (Nutramigen, Pregistimil, Alfare, Pepti-Junior and Pregomin), and crude peanut protein extract. The molecular weight distribution for the peanut extract and the hydrolysates ranged between 5-200kDa and 2-17kDa respectively.