Biorefinery concept for discarded potatoes: Recovery of starch and bioactive compounds

The integral valorisation of discarding potatoes from three local varieties using processes of low environmental impact to recover the starch contained in the flesh as well as the bioactive compounds present in the skin or in the processing wastewaters was studied. The remaining flesh after starch extraction was also recovered to further processing. The extraction of starch and active extracts using environmentally friendly technologies, the physicochemical and phytochemical characterisation of the extracts, the formulation and mechanical characterisation of the corresponding functional hydrogels, have allowed proposing potential food and non-food applications. Results indicated that subcritical water extraction (220 °C) was an efficient technology to recover antioxidants from the potato skin. Processing wastewaters exhibited high protein content. The extracted starch featured comparable physicochemical properties to that available commercially and the corresponding hydrogels exhibited enhanced mechanical properties with absence of syneresis. It should be remarked that Agria and Neiker varieties provided the highest total starch and bioactive content in terms of phenolics, TEAC value and DPPH inhibition percentage, respectively.