Abstract
Ultraviolet (UV) irradiation at 254 run and doses of 300 mWs/cm2 from a photochemical reactor (16.6 min at 300 μW/cm2) or 4.8 Ws/cm2 from a high intensity UV‐C lamp (40 sec at 120–180 mW/cm2 reduced surface microbial count on mackerel by two to three log cycles. UV treated mackerel wrapped in 1 mil polyethylene and packed in ‐1°C ice had at least a 7 day longer shelf life than conventional ice‐packed untreated controls. Spray washing with water containing 10 ppm chlorine by itself or in combination with UV irradiation was necessary to reduce surface counts on rough surfaced fish to the same extent as that on smooth surfaced fish. When UV irradiated and packed in 0°C ice, surface microbial counts on vacuum packaged mackerel lagged by 4 days those on mackerel wrapped in 1 mil polyethylene.