Beetroot Microgreens (Beta vulgaris) Powder Obtained by Cast-Tape Drying and Freeze-Drying

The study aimed to dehydrate beet microgreen foams using cast-tape drying and freeze-drying to obtain powder and characterize them in terms of physicochemical properties and betalain. Foam formulations were analyzed: F1 = 78.3% water + 13% microgreens + 6.5% Emustab + 2.2% pre-gelatinized starch; F2 = 78.3% water + 13% microgreens + 4.4% pre-gelatinized starch + 4.3% Emustab. The formulated foams were dried using cast-tape drying (CTD) (70°C and 2 mm spreading thickness) and freeze-dried (FD). The drying time for CTD was 12 min for CTDF1 and 24 min for CTDF2 (moisture of 0.1 g/g). The FD time was 14 h for FDF1 and 18 h for FDF2 (moisture of 0.02 g/g). The water activity and moisture content of the powder obtained by CTD were lower than that of the FD powder for both formulations, and the protein content in F2 (4%–4.6%) was lower than in F1 (5.2%–6.3%). The foam allows for the rapid drying of beet microgreens by CTD due to the high drying rate and moderate temperature. The CTDF2 powder has lower moisture and activity water, violet/red coloration, good flowability, and low cohesiveness compared to the other samples. Freeze-drying shows higher betalain retention (FDF1). Microgreens in powdered form constitute viable protein sources to be incorporated into plant-based products, while betalain allows using this powder as a natural dye. These potential applications demand further investigation, aiming at a potential introduction as a new product in the market.