The effect of gamma‐irradiation and pasteurisation on the composition of dry cat food formulation

Abstract

Removing microbial contamination (e.g. by irradiation) in diet is vital for housing animals in a barrier facility such as in an SPF environment. Relatively little is known about the long term feeding of gamma-irradiated diets to cats. This study investigated the effect of gamma-irradiation (28.9–34.3 or 38.4–48.7 KGy) and pasteurisation (107°C for 15 min) on nutrients in a dry cat diet. Fat, protein, carbohydrate, taurine, vitamins A, E, B1, B2, B6 and B12, and peroxide were measured using established analytical methods. Irradiation reduced vitamin A content to 42% (lower dose) and 31% (higher dose) of its untreated value, as did pasteurisation (to 50%). Peroxide was increased to 1,100% (lower) and 2,100% (higher), whilst pasteurisation modestly increased this parameter (117%). It can be concluded that gamma-irradiation, at the doses employed in this study, has profound effects on vitamin A and peroxide content in dry cat food, and that caution should be employed when such diet is considered for long-term feeding. It would be recommended that pasteurisation of cat diet should be considered as a viable alternative.