The influence of processing and preservation on the retention of health-promoting compounds in broccoli

In this work the effects of common household practices such as chilling, freezing, and coking on vitamin C retention in broccoli (Marathon cv.), as well as their influence on the release of sulforaphane upon enzymatic hydryolysis of glucoraphanin by the endogenous enzyme myrosinase, were investigated. When chilled at 6 degrees C and 95% R.H. for 35 d, broccoli showed a vitamin C and sulforaphane loss of about 39% and 29%, respectively, while storage at -18 degrees C for 60 d resulted in similar losses, but mainly due to the blanching step. Boiling, steaming, microwaving, pressure-cooking, and the combined use of pressure and microwaves were the cooking methods investigated. Boiling and steaming caused significant vitamin C losses, 34% and 22%, respectively, while with the other treatments more than 90% retention was observed. Sulforaphane was no more detectable after boiling or steaming, while pressure/microwave cooking did not cause any significant loss. the quantitative distribution of these moieties in the florets and stems of fresh and chilled broccoli was also investigated.