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Broccoli is a rich source of glucoraphanin, which is converted into the bioactive sulforaphane upon cell disruption by the activity of endogenous myrosinase. Conventional broccoli processing involves heating that inactivates myrosinase. We investigated the feasibility of lactic acid bacteria (LAB) fermentation as an alternative process for maintaining myrosinase activity and enhancing the biotransformation of glucoraphanin into sulforaphane. LAB fermentation inhibited the growth of undesirable spoilage and pathogenic microorganisms in broccoli puree and increased the yield of sulforaphane in the puree from 845 to 1617 μmol/kg dry matter (DM). High sulforaphane content was observed in the fermented puree throughout storage especially at 4 °C; the sulforaphane content after ∼three months storage was 1012.9 μmol/kg DM, 62.6% of the level just after fermentation. The results indicate that fermentation enables the production of safe, stable and sulforaphane rich broccoli product that can be used as a dietary supplement or potentially an ingredient in functional foods.

Abstract: A robust method for the determination of glucoraphanin in broccoli (brassica oleracea ssp. italica ‘Marathon’) seeds and florets has been developed using solid phase extraction (SPE) and micellar electrokinetic capillary chromatography (MECC) as the determinative step. Glucosinolates were extracted from the broccoli seeds and florets with hot water. Unwanted impurities were removed by passing the extracts through C18 and protonated amino propyl SPE cartridges connected in series. The glucosinolate fraction was removed from the protonated amino propyl cartridge with 2% v/v ammonia solution in methanol. The solvent was removed with a stream of nitrogen, the residue dissolved in water and the level of glucoraphanin determined by MECC using a 77cm×75-μm id bare fused silica capillary column (effective length 69.4cm) and a buffer consisting of 18mM sodium tetraborate, 30mM sodium dihydrogen orthophosphate and 30 mM cetyltrimethylammonium bromide, pH 7. MECC parameters and capillary conditioning procedures were optimised with respect to reducing the analysis time without compromising peak integrity. The level of glucoraphanin in broccoli seeds and florets compared favorably with the levels determined by a validated high performance liquid chromatography (HPLC) literature procedure; broccoli seeds MECC 2.1 gm/100g, HPLC 2.0 gm/100g; broccoli florets, MECC 71mg/100g, HPLC 70mg/100g. The MECC instrument reproducibility data (n =7) for glucoraphanin in broccoli seed and floret extracts for migration time (CV; seeds 1.2%, florets 2%) and area calculation (CV; seeds 3.7%, florets 7%) relative to the internal standard were suitable. [Copyright &y& Elsevier]

• Lactic acid bacteria fermentation resulted in safe and stable broccoli product. • Increased total polyphenol content by 85%. • Increased ORAC antioxidant capacity by 70%. • Doubled sulforaphane yield compared to control. Broccoli is a rich source of glucoraphanin, which is converted into the bioactive sulforaphane upon cell disruption by the activity of endogenous myrosinase. Conventional broccoli processing involves heating that inactivates myrosinase. We investigated the feasibility of lactic acid bacteria (LAB) fermentation as an alternative process for maintaining myrosinase activity and enhancing the biotransformation of glucoraphanin into sulforaphane. LAB fermentation inhibited the growth of undesirable spoilage and pathogenic microorganisms in broccoli puree and increased the yield of sulforaphane in the puree from 845 to 1617 μmol/kg dry matter (DM). High sulforaphane content was observed in the fermented puree throughout storage especially at 4 °C; the sulforaphane content after ∼three months storage was 1012.9 μmol/kg DM, 62.6% of the level just after fermentation. The results indicate that fermentation enables the production of safe, stable and sulforaphane rich broccoli product that can be used as a dietary supplement or potentially an ingredient in functional foods. [ABSTRACT FROM AUTHOR]