Factors Influencing Sulforaphane Content in Broccoli Sprouts and Subsequent Sulforaphane Extraction

Abstract

Broccoli sprouts contain 10–100 times higher levels of sulforaphane than mature plants, something that has been well known since 1997. Sulforaphane has a whole range of unique biological properties, and it is especially an inducer of phase 2 detoxication enzymes. Therefore, its use has been intensively studied in the field of health and nutrition. The formation of sulforaphane is controlled by the epithiospecifier protein, a myrosinase co-factor, which is temperature-specific. This paper studies the influence of temperature, heating time, the addition of myrosinase in the form of Raphanus sativus sprouts in constant ratio to broccoli sprouts, and other technological steps on the final sulforaphane content in broccoli sprout homogenates. These technological steps are very important for preserving sulforaphane in broccoli sprouts, but there are some limitations concerning the amount of sulforaphane. We focused, therefore, on the extraction process, using suitable β-cyclodextrin, hexane and ethanol, with the goal of increasing the amount of sulforaphane in the final extract, thus stabilizing it and reducing the required amount sulforaphane needed, e.g., as a dietary supplement.

Maximization of Sulforaphane Content in Broccoli Sprouts by Blanching

“…The optimum conditions that maximize SFN content were blanching at 61 • C for 4.8 min. The optimum temperature coincides with Tríska et al [17], who concluded that temperature is the key factor in SFN formation in broccoli sprout processing, and that its optimum should range between 60 and 70 • C. Our values match the best temperature reported by [19] for broccoli sprouts (60 • C) and are close to the optimum reported by Pérez et al [10] for broccoli florets (57 • C for 13 min). Our results also agree with Mahn et al [11], who reported an increase of SFN content in broccoli florets by 2-fold in comparison with its fresh state when an ultrasound-assisted blanching was applied at 60 • C for 4 min.…”

“…In the present work, we achieved a 330% increment compared to fresh sprouts. The exceptionally high values obtained in this work may be related to the treatment but also to the broccoli cultivar and the culture conditions, which differ from that reported elsewhere [17,23].…”

“…Higher blanching temperatures and shorter immersion times favor glucoraphanin hydrolysis, agreeing with the statistical results obtained for sulforaphane. This result agrees with [17]. The significant positive effect of immersion time on GFN content may be related to tissue softening, which facilitates diffusion during the extraction process in analytical determinations.…”

“…The SFN content achieved in the present study (~54 µmol/g DW) is the highest reported for broccoli sprouts subjected to any treatment so far. Tríska et al [17] reported a maximum SFN content of 33 µmol/g of lyophilized sprouts powder subjected to hydrothermal treatment with the addition of exogenous myrosinase. This value represents 61% of the content achieved in the present work.…”

“…The effect of processing conditions on SFN content in broccoli sprouts has been poorly studied. Triska et al [17] investigated different hydrothermal treatments of broccoli sprouts on SFN content, with the main focus on the extraction process. They reported that high temperatures increase SFN formation, but those results were not reproducible at a semi-productive level because of the heterogeneous temperature profile in the batch.…”