ABSTRACTHydrogen sulfide production during heating of raw, precooked, and canned tuna was studied by reflux‐trap technique. Raw tuna homog‐enate did not produce hydrogen sulfide gas when heated at less than 90°C. Canned and precooked samples produce substantially higher amounts of H2S during heating than the raw substrate. Maximum H2S production rate occurred after 150 min for raw, 90 min for precooked, and 60 min for canned samples. An apparatus was devised for quantitative determination of H2S gas present in a sealed can of tuna. Cans of control albacore tuna (Thunnus alalunga) packed in water or oil and retorted for 80 min contained higher amount of H2S than the spoiled cans. Hydrogen sulfide content, volatile acids, volatile reducing substances, and histamine values of both the control and the spoiled canned tuna increased significantly as the retort lime was extended from 80 to 120. to 240 min. Headspace profile of canned tuna volatiles was determined by gas chromatography. Examination of the chromatograms indicated a considerable increase in concentration of volatiles as the retort time was extended from 80 to 120 to 240 min in both control and spoiled substr
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