The aim of this work was to find the most useful inorganic nitrogen source to enable Leucopaxillus giganteus to become a more nutritious mushroom, regarding organic acid and phenolic composition and total alkaloids content. For these, the influence of NH4NO3,NaNO2, KNO3,, and (NH4)2HPO4 on the organic acid production was determined by HPLC-UV and total alkaloid content was assessed by a spectrophotometric method, after precipitation by Dragendorff’s reagent. The results showed that L. giganteus presented an organic acid profile composed of oxalic, cis-aconitic, citric, and fumaric acids, citric acid being the major one. The quantitative organic acid profile and total alkaloid content were affected by the nitrogen source and depended on the developmental stage of mycelium and nitrogen availability. Despite being present in all samples, no phenolic compound could be identified.
