Effect of storage, processing and cooking on glucosinolate content of Brassica vegetables.
Level 5 - mechanism / opinion, no new human data
Laboratory food chemistry study with no human subjects.
PubMed 17011103 · doi:10.1016/j.fct.2006.07.021
What was done
Researchers evaluated the stability and retention of the seven major glucosinolates and their conversion to isothiocyanates in broccoli, Brussels sprouts, cauliflower, and green cabbage under different storage and culinary conditions. Compounds were quantified using liquid chromatography with tandem mass spectrometry (LC-MS/MS). Tested conditions included storage for 7 days at ambient vs. refrigerator temperatures, post-shredding dwell times up to 6 hours, and various cooking methods (steaming, microwaving, stir-frying, and boiling).
What was found
Storage for 7 days showed no significant difference between ambient and refrigerated temperatures, with only minor glucosinolate loss (9% to 26%). Fine shredding caused a rapid decline in glucosinolate content (up to 75% loss over 6 hours), with losses detected partly as isothiocyanates. Steaming, microwaving, and stir-frying resulted in no significant glucosinolate loss. In contrast, boiling caused significant losses primarily due to leaching into the cooking water, where approximately 90% of the lost glucosinolates were recovered.
Why it matters
Cooking and food preparation methods dictate the retention of cancer-preventive glucosinolates in Brassica vegetables. Avoiding boiling (or consuming the cooking water) helps preserve dietary glucosinolate intake.
Limits
This was an in vitro food chemistry study without human in vivo bioavailability, metabolic, or clinical outcome measurements. The abstract does not specify sample sizes, replicate counts, or exact baseline concentrations.
Cited by
- supports Microwaving broccoli causes less leaching of phytochemicals and plant juice into cooking liquid compared to boiling or heavy steaming.