Microwave-Assisted Extraction of Pectin from Pickled Cabbage Waste: Process Optimisation, Characterisation and...

This study optimised pectin extraction from pickled cabbage waste using microwave-assisted extraction (MAE), characterised the extracted pectin, and explored its potential for low-sugar jam production. The Box-Behnken design concluded that the optimal conditions are 539 W (microwave power), 116 s (time), and pH 1.5, yielding a pectin yield of 22.53 ± 2.63%. The physicochemical analysis revealed that the microwave-extracted pectin (MEP) was low methoxyl and had a high molecular weight (1.20 ± 0.004 MDa). It was composed of galacturonic acid, arabinose, rhamnose, xylose and glucose. FTIR, ¹H NMR and SEM results also confirmed structural characteristics of MEP. MEP was confirmed to have remarkable technological properties, including an emulsion activity of 53.43 ± 2.19% and good stability over 30 days at 4 °C and 24 °C. Moreover, it has an oil-holding capacity of 1.18 ± 0.51 g oil/g pectin and an elevated water-holding capacity (9.36 ± 3.25 g water/g pectin). The application of MEP as a stabiliser in low-sugar jam enhanced viscoelastic characteristics of jam, like apple pectin, and G' > G″ confirmed the improved shelf-life stability at 25 °C. This study emphasised that microwave-assisted extraction can be a sustainable, time- and energy-saving method for the valorisation of pickled cabbage waste, and highlighted the effect of MEP on the characteristics of low-sugar jam.