Gravitational and microwave-assisted multi-stages block freeze concentration process to obtain enriched concentrated beet (Beta vulgaris L.) by-products extract: bioactive compounds and simulated gastrointestinal profile

Abstract

Gravitational (GC) and microwave-assisted (MWC) block freeze cryoconcentration was carried out to obtain extracts rich in phenolic compounds from beet leaves extract. The performance of both processes was evaluated and cryoconcentrated and ice fractions were analyzed for physicochemical properties, bioactive compounds content, and in vitro gastrointestinal simulation. After four concentration cycles using GC, the total and soluble solids were approximately 6 and 5 times higher the initial condition, whilst MWC allowed to 4 and 4.5, respectively. GC and MWC presented an increase in the bioactive compound concentration, reaching an efficiency process of 90% (stage 4) and 80% (stage 3), respectively. Consequently an increase in the antioxidant activity was observed. Comparing GC and MWC was observed a reduction in the processing time from several hours (GC) to only a few minutes (MWC), besides the high retention of bioactive compounds, as well as notabl values in terms of solutes and process parameter.