2017 ASHS Annual Conference

Producing broccoli on the East Coast could decrease the time between harvest and consumption. The objective of this experiment was to evaluate the impact of storage temperature and duration on broccoli grown on the east coast. A randomized complete block trial was conducted using two broccoli varieties (Pacman and Arcadia) obtained from a local grower. At harvest, broccoli was sorted into containers set up for four replications each of two storage conditions: 0°C (iced at harvest) and 4°C (cooled in storage). Broccoli heads were sampled weekly for five weeks during postharvest storage, including the day of harvest. Florets were freeze-dried, ground, and analyzed for 13 glucosinolates. Data reported here are for glucoprogoitrin, a nutritiously harmful glucosinolate, glucoraphanin and glucobrassicin due to their anti-carcinogenic properties, and total glucosinolate content. A complete volatile profile was analyzed using the fresh frozen tissue. Here we report dimethylsulfide as an indicator of an off-flavor volatile, and eucalyptol as an indicator of a desirable flavor volatile. Data were analyzed using mixed model analysis of variance (Glimmix procedure, SAS Institute, Cary, NC). Glucoprogoitrin was not affected by storage time or temperature for either cultivar. Glucobrassicin and glucoraphanin were found in significantly greater quantities in both cultivars stored at 0°C (P<0.05). Glucobrassicin was 45% greater at 35 days post-harvest for the Pacman cultivar than at harvest (P=0.0467). Overall, Pacman broccoli had significantly greater total glucosinolate content at 35 days post-harvest than at harvest (P<0.05). Arcadia had significantly greater total glucosinolate content when stored at 0°C (P<0.05). Dimethylsulfide was greater in Pacman broccoli stored at 4°C (P=0.0195) and at 28 and 35 days post-harvest compared to at harvest, 7, and 14 days post-harvest (P<0.001). Eucalyptol was also greater at 4°C (P<0.001); however, eucalyptol was not detected past 21 days post-harvest. Eucalyptol content was significantly greater at harvest than 7 and 14 days post-harvest (P<0.001). Neither storage temperature nor time greatly affected nutritionally harmful glucosinolates. However, both cultivars of broccoli stored at 0°C had a higher concentration of anti-carcinogenic glucosinolates. Undesirable flavor volatiles were increased by the increase in temperature and time. Desirable volatiles were reduced by the increase of storage time. This study indicates that storing broccoli at 0°C for no longer than 14 days is optimum to maintain the quality parameters evaluated. Future experiments are needed to evaluate a broader range of post-harvest temperatures for impact on these and other quality parameters.