Background: Vegetables and fruits are consumed in considerable amounts worldwide
producing huge quantities of organic leftovers comprising primarily of peels. Peels of potatoes (PP) and
carrots (CP), for instance, are often considered as waste, albeit they still represent a rich source of
interesting phytochemicals. Traditional waste management of such materials, usually vermicomposting,
therefore represents a low-value approach and also a considerable burden to the environment.
Objective: Aiming to convert some of this waste into raw materials for further applications,
methods were explored to prepare suspensions of PP and CP. Antioxidant activities of these
suspensions were compared to bulk-suspensions and the corresponding ethanolic extracts in
anticipation of possible applications in Nutrition and Cosmetics.
Methods: The peels of potatoes and carrots were subjected to high- speed stirring (HSS) and highpressure
homogenization (HPH) to produce suspensions which were characterized for size
distribution by Laser Diffraction (LD), Photon Correlation Spectroscopy (PCS), and light
microscopy (LM). Ethanolic extracts of peels were also produced. Samples were evaluated for
antioxidant activity employing 2,2-diphenyl-1-picrylhydrazyl (DPPH) assay.
Results: HPH produced suspensions of peels comprising particles with diameters in the range of
268 - 335 nm for PP and 654 - 1,560 nm for CP. These suspensions exhibited a significantly
stronger antioxidant activity compared to the bulk-suspensions. Moreover, the suspension of PP
(1% w/w) exhibited comparable antioxidant activity to the ethanolic extract (1% w/w) whilst the
CP suspension (1% w/w) exhibited lower activity compared to the ethanolic extract.
Conclusion: Production of suspensions of vegetable peels may unlock some biological potential
which could be optimised for applications in Nutrition, Agriculture, Medicine and Cosmetics.