Thermal treatment of protein is known to reduce protein quality and the des
truction of certain amino acids. Fish and chips stili remain a popular food
source in Britain. Little work has been done on the changes in protein qua
lity during fish frying. The paper will present results obtained from the a
ssessment of protein quality using net protein utilisation (NPU) in fried a
nd steamed fish. Weanling male Sprague-Dawley rats were given stock diet (R
M1 expanded, SDS Ltd., Witham, Essex) for 7 days at 30 days of age, groups
of four were offered one of four diets that differed only in the type of fi
sh and processing used. Diets contained 200g of fish protein, 550g carbohyd
rate (400g sucrose and 150g corn-meal), 50g mineral and vitamin mix and 200
g fat/kg diet. The different fish species used were Cod and Plaice and the
processing used was either steaming or frying. Although a fall in NPU was n
oted in fried fish compared to the steamed fish these changes in NPU could
be reduced if the fish was covered with batter prior to frying.