Assessment of plant tissue disintegration degree and its related implications in the pulsed electric field (PEF)-assisted aqueous extraction of betalains from the fresh red beetroot

In this study, we performed the pulsed electric field (PEF)-assisted aqueous extraction of betalains from fresh red beetroot, simultaneously evaluating a disintegration degree of red beetroot tissue. The extraction results showed that the application of 3 pulses (1 Hz) with 100 mu s duration and 2.0 kV/cm pulse strength (delivering total specific energy of 2.53 kJ/kg) resulted in extraction up to similar to 70% (extracted for 1 h at 22 degrees C) of total betalains. It was observed that at low specific energy inputs (0.8 and 2 kJ/kg - 0.5, 1.0, 1.5 and 2.0 kV/cm), the PEF treatment duration has a significant effect on the extraction yield of betalains. We show that comparing the efficiency of PEF treatments with different PEF strengths and durations, but the same specific energy inputs (0.8, 2.0, and 4.0 kJ/kg), higher permeabilization index (Z(p)) does not refer to a higher extraction yield of betalains. Industrial relevance: PEF-assisted aqueous extraction of betalains from the fresh red beetroot is effective, energy favourable and environmentally friendly method and could serve as an alternative to the conventional extraction techniques. Our study shows that the extraction yield of betalains is better reflected by measurements of supernatant conductivity rather than Z(p).

Automated summary

In this study, betalains were extracted from fresh red beetroot using pulsed electric field (PEF)-assisted aqueous extraction. The duration of PEF treatment significantly affects the extraction yield of betalains under low specific energy inputs. Higher permeabilization index (Z(p)) does not necessarily lead to a higher extraction yield of betalains, and measuring the supernatant conductivity is a better reflection of the extraction yield.