The Cultivation of the edible mushrooms Pleurotus ostreatus on spent ground coffee was studied with the purpose of evaluating its potential as a treatment method for the valorization of this coffee waste. Its nutritional composition of macro and micronutrients was also evaluated as a quality control, to verify that the food product (oyster mushrooms) is of high nutritional value and free of toxic substances for human consumption. The influence of the amount of mycelial seed on the efficiency of production of the edible mushrooms was investigated, obtaining an optimal quantity between 10 and 20 % (g seed /100 g wet substrate) with a biological efficiency of roughly 60 %. The protein value was of 47.3 % on dry sample, with a high-water content (~ 90 %) and a low content in carbohydrates (5.4 %) and fats (0.2 %) in fresh sample. The analysis of microelements in the oyster mushrooms shows th...