Recovery of added value compounds from beetroot juice industry wastes

Kottaridis, Sotirios and Papaioannou, Emmanouil and Douglas, Timothy and Martin, Alastair (2021) Recovery of added value compounds from beetroot juice industry wastes. Masters thesis, Lancaster University.

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Abstract

The aim of this research work is the recovery of added-value compounds from beetroot juice industry wastes. The recovery of added-value compounds from wastes is a waste valorisation strategy, which can lead to the reduction of the environmental footprint and the creation of additional revenue for companies. In this work, the beetroot pomace is extracted mainly for the recovery of betalain pigments and phenolic compounds, using enzymatic-aided extraction. The extractions were performed in lab- and semi-pilot scales, using aq. ethanol solvents, and were compared to conventional extraction. The semi-pilot extracts were further subjected to UF and NF membrane cascade processing, for their clarification and the fractionation, concentration and purification of the potentially extracted compounds. The initial analysis of the raw beetroot extracts and the beetroot juice, from the production of which the beetroot pomace derives as a waste, led to the detection of several betalain pigments. In contrast, the lab scale extraction of the beetroot pomace did not unveil any beetroot compounds, even after using different enzymatic treatment/extraction conditions and pomace batches. The semi-pilot conventional and enzymatic extraction of the beetroot pomace did not lead to the detection of any beetroot compound, using HPLC-DAD and LC-ESI-MS chromatography, apart from a single compound, which could not be qualitatively determined. A colour change from green to blue was interestingly observed among the various retentate NF streams, but could not be correlated to individual pigments. Finally, the conventional extraction of the beetroot pomace using pure organic solvents demonstrated the presence of only low betanin amounts, solely in the methanol extracts. These findings suggest that the beetroot pomace is depleted in most pigments; also, methanol cannot be combined with the commercial enzymes and the membranes in use. It is, therefore, concluded that the initial investigation has been completed and there are no further objectives.