(P06-046-23) Fermentation of Kale (Brassica oleracea var. sabellica) Vegetable Enhances Its Properties as a Functional Food

Objectives: The vegetable Kale (Brassica oleracea var. sabellica) is abundant in bioactive compounds like glucosinolates, phenolics, and carotenoids. In previous studies, we have shown that supplementation with Kale attenuates chronic and acute inflammation and modulates gut microbial function in C57BL/6J mice. In this follow-up study, we sought to explore how fermenting Kale impacts its functional food properties. We hypothesized that fermentation would enhance these properties.

Methods: Using a randomized design of 6 treatments and a control (unfermented) we tested (i) spontaneous fermentation with natural bacteria in the vegetable (ii) fermentation after addition of 2% salt (w/w), (iii) adding 10^7 CFU/g of Lactococcus lactis (ATCC 11454), (iv) Lactobacillus acidophilus (ATCC 314), (v) mixed culture of L. lactis and L.acidophilus, and (vi) a mixture of L. lactis, L. acidophilus, and Clostridium butyricum. After 3 weeks fermentation at room temperature, samples were freeze-dried and powdered. We quantified total polyphenols, flavonoids, and carotenoids by spectrophotometric methods. Antioxidant activity (DPPH assay) was assessed. Beta-carotene content was quantified by HPLC. Microbiota composition of the vegetable was determined by 16S rDNA sequencing.

Results: Total polyphenols, flavonoids, and antioxidant IC₅₀ value were not significantly changed by fermentation and ranged from 9.22 to 10.64 mg GAE/g, 5.35 to 6.20 mg QE/g, and 186.70 to 378.50 ug/ml respectively. A significant decrease in beta-carotene and total carotenoid content was observed in all fermented groups compared to the control. For microbiota composition, the relative abundance of Bacteroidetes, and Cyanobacteria decreased while Firmicutes increased in all fermentation groups. Fermentation increased order Lactobacillales. Ongoing studies on these samples focuses on comparing anti-inflammatory effects of fermented kale to that of the control in a cell culture model of Macrophages.

Conclusions: Fermented kale is a vehicle for the delivery of, probiotics, and thus the food acts, as a prebiotic. Fermentation with a mixed culture of L. lactis and L. acidophilus increased the abundance of health-beneficial bacteria compared to other fermentation groups.

Funding Sources: New laboratory startup funds awarded to Dr. Diana Obanda by the University of Maryland, College Park, MD.