Promoting a circular economy by developing new gastronomic products from brassica non-edible leaves

Abstract

This study aims to apply circular economy principles by reintroducing discarded Brassica leaves into the value chain as innovative products. Non-edible leaves of three Brassica varieties were used to develop kombucha, a fermented beverage with health benefits. The fermentation time (9 days), temperature (25 °C), starter culture, and container shape (2 L round-shape glass jar) influenced the beverage's physicochemical properties, including pH, vitamin content, polyphenols, and sugar levels. Different Brassica varieties showed various effects on antioxidant capacity and polyphenol content during fermentation, with potential implications for microbial engagement. Sensory analysis revealed differences in appearance, colour, aroma, and taste between black tea and Brassica samples, which are due to glucosinolates and volatile compounds, thus providing opportunities for improving consumer acceptability through flavour masking. Overall, this work showcases the potential of using non-edible Brassica by-products and highlights the potential of fermented beverages like kombucha to address food waste and promote value addition from otherwise discarded plant parts