HEAT-INDUCED ALTERATION OF METHANETHIOL EMISSION FROM ANAEROBIC BROCCOLI FLORETS

The influence of heat applied before and during the imposition;of anae robic conditions on methanethiol (MT) production of broccoli (Brassica oleracea L. Italica group) was studied, Ten minute heat treatments of temperatures ranging from 40 to 60 degrees C imposed on broccoli flor ets prior to the initiation of 18 h of anaerobic conditions strikingly altered the course of MT production and respiration. Heat treatment a t 40 and 45 degrees C greatly diminished MT production compared with 2 5 degrees C during the first 6 h. In contrast, MT production was stimu lated at 55 degrees C and completely eliminated at 60 degrees C. The r espiratory rate of broccoli treated at 50 degrees C was increased, whe reas at 45, 55 and 60 degrees C the rates were decreased compared with that of 25 degrees C. The rate of respiration at 40 degrees C was sim ilar to that at 25 degrees C. The amount of hydrogen sulfide (HS) and dimethyl disulfide (DMDS), two other sulfur gases also emitted under a naerobic conditions, was increased by heat treatment. Heat treatment g iven concurrently with the formation of MT during 24 h of anaerobiosis increased MT production and respiration. The relative amounts of HS, DMDS and MT were unchanged by heat treatment. The results indicated th at the mechanism for MT production in broccoli is highly sensitive to alteration by heat.