Evaluation of nineteen food wastes for essential and toxic elements

Purpose The study evaluates and provides an overview ofthe nutritional importance of 19 selected food wastes asaids in human/livestock/soil/plant health.Methods Nitric acid-digested extracts of food wastesbelonging to four different classes (fruits, vegetables, oilseedsand beverages) were analysed for different elementsin an inductively coupled plasma mass spectrometer.Results Our study recommends spent coffee grounds, tealeaves, radish peel, watermelon rind and pineapple skinthat contain substantially high concentrations of essentialelements such as N, P, K, S and Fe for their use as:(a) substrates for composting, (b) biofertilizers, (c) soilamendments, and (d) bioadsorbents of toxins. Althoughthese food wastes are rich in essential nutrients, we do notsuggest them for the preparation of food supplements asthey contain non-essential elements in concentrationsbeyond the human safety limits. However, food wastes likebanana peel, plum pomace and pistachio shell that containlow and permissible concentrations of toxic elements canbe recommended as dietary supplements for oral intake inspite of their lesser essential elemental composition thanthe other residues examined.Conclusions Our study confirms that food wastes are richsources of essential nutrients and there is need to harnesstheir real industrial systems.