Microwave assisted dehydration of broccoli by-products and simultaneous extraction of bioactive compounds.

Broccoli by-products from frozen-food industry account for 45% of the initial broccoli heads. They consist on stalks, inflorescences, and leaves, blanched and non-blanched, sharing the nutritional value and bioactive compounds of commercial broccoli heads. However, their high perishability prevents further valorisation. Therefore, in this study microwave hydrodiffusion and gravity (MHG) technology was used to dehydrate broccoli by-products and simultaneously recover the water-soluble diffused compounds for food ingredients use. The hydrodiffusion allowed to obtain a dried material with 12% moisture in 43 min when 550 g of broccoli by-products were used, preserving polysaccharides and proteins. Diffused water contained up to 317 µg/mL gallic acid equivalents of phenolic compounds, 11 mg/mL free sugars, 9 mg/mL amino acids, and 356 µg/mL glucosinolates, depending on the type of by-product used. These results show the potential of MHG technology for valorisation of broccoli by-products by its simultaneous stabilization by dehydration and extraction of bioactive compounds.