Brussels sprouts are a source of polyphenolic compounds. However, their concentration is affected by many factors depending on the plant material, hydrothermal treatment methods and digestion in the gastrointestinal tract. The aim of this study was to determine the effect of hydrothermal treatment on the antioxidant activity, concentration and profile of polyphenols of Brassica oleracea var. gemmifera in an in vitro simulated gastrointestinal digestion model. The study showed a significant effect of the type of hydrothermal treatment on total polyphenol concentration, polyphenolic acid profile, flavonoid content and antioxidant activity. Traditional boiling in water was the least effective type of hydrothermal treatment with respect to bioactive components of Brussels sprouts. Sous-vide was the most effective hydrothermal treatment in terms of retention of polyphenolic compounds and high antioxidant activity, thus providing a better alternative to steam cooking. Using an in vitro model, a significant difference was demonstrated between the concentration of bioavailable polyphenolic compounds and the polyphenol content of the plant material before digestion. The influence of the type of hydrothermal treatment used on the concentration of bioavailable polyphenolic compounds was maintained in relation to material not subjected to in vitro digestion (except for antioxidant activity).

Hydrothermal treatment of Brussels sprouts (Brassica oleracea var. gemmifera) induces both physical and chemical changes in nutrients and non-nutrients. It also affects the bioaccessibility of individual compounds. The aim of this study was to investigate the influence of hydrothermal treatment (boiling, steaming, and sous vide technique) on the concentration of the selected nutrients and non-nutrients in Brussels sprouts and in vitro bioaccessibility of the mineral components. It has been shown that, in terms of the leaching of nutrients and non-nutrients into the aqueous medium, traditional cooking in water involves the greatest percentage loss (the highest decrease in dry matter (11.8%), ash (13.3%), protein (10.4%), crude fat (43.3%), dietary fiber (9.5%), digestible carbohydrates (12.2%), and most of mineral components (7.6–39.8%)). In contrast, steam cooking and sous vide cooking of Brussels sprouts allow a higher level of preservation of the individual compounds. By using reduced process temperatures and vacuum packaging, sous vide cooking can be an alternative to traditional cooking to preserve the higher nutritional value of Brassica oleracea var. gemmifera (preservation of dry matter, ash, crude fat, and most of the mineral components at the level of the raw sample p ≤ 0.05).

Due to significant concentration of polyphenols, diet with a high amount of plants such as Brassica vegetables is associated with health beneficial properties. Brassica vegetables are mostly consumed processed, what affect the polyphenol level. The most popular processing methods of Brassica vegetables include boiling them with salt addition. The correlation between increased NaCl intake and high blood pressure has resulted in the search for salt substitutes such as KCl. The purpose of this study was to determine the influence of NaCl and KCl addition (0.0, 0.5, 1.0, 2.0, 3.0 g/100 g) during hydrothermal treatment on polyphenolic acid content in selected Brassica vegetables. A significant influence on polyphenolic acid content in Brassica vegetables when boiling with the addition of NaCl and KCl was shown. Caffeic acid was impacted the most after salt addition. Boiled cauliflower had the greatest decrease of the analyzed polyphenolic compounds out of all the vegetables studied.

Brussels sprouts provide bioactive compounds with widely acknowledged health-promoting effects observed in various levels: single cells, organs and tissues, or the whole organism. However, the choice of the appropriate hydrothermal processing is critical to sustain the nutritional values and cytoprotective activities, as Brussels sprouts are rarely eaten raw. The aim of this study was to evaluate the impact of various culinary methods (boiling, steaming, and sous-vide in comparison to raw plant material) applied to Brussels sprouts on the chosen functions of liver and intestinal cell lines (HepG2 and Caco-2, respectively): the markers of enterocyte differentiation (alkaline phosphatase and sucrase-isomaltase activities and protein level), glutathione store management (total GSH concentration and Glu, Gly, Cys and Met amino acids analysis) and mitochondrial polarization (JC-1 staining analysis). The in vitro digestates from raw Brussels sprouts had a stronger positive effect on the enterocyte marker enzymes in the Caco-2 cultures as compared to the digestates from the hydrothermally processed vegetables (boiled, steamed, and sous-vide). The sous-vide method diminished the intracellular glutathione stores. Hydrothermal processing, particularly steaming and sous-vide had a negative impact on the mitochondrial abundance and polarization as compared to raw vegetables. Our results suggest that shorter processing is more beneficial to retain glutathione and mitochondrial polarization than longer hydrothermal treatment.