Nutritional value and thermal degradation of bioactive compounds in wild edible mushrooms

Introduction: Nutritional potential of wild edible mushrooms and loss of their nutraceutical properties during cooking have been little examined. Objective: To evaluate the nutritional content and effect of heat treatment on nutraceutical properties in the wild species Lactarius indigo (Schwein.) Fr. (blue mushroom), Ramaria flava (Schaeff.) Quel. (changle) and Hypomyces lactifluorum (Schwein.) Tul. & C. Tul. (lobster mushroom), collected in temperate pine and oak forests of the Sierra Norte de Puebla. Materials and methods: The mushrooms were collected in the company of "traditional mushroom collectors". Proximal composition was quantified according to AOAC methods. The effect of heat treatment was evaluated at 50 and 92 degrees C at 10 to 60 min intervals. Total phenolic content was determined by the Folin-Ciocalteu method and antioxidant capacity by ABTS and FRAP assays. Results and discussion: R. flava and L. indigo had the highest percentages of protein (24.02 %) and crude fiber (14.64 %) on dry basis, respectively. R. flava had the highest phenolic content (4.40 mg gallic acid equivalents per gram dry basis) and the highest antioxidant capacity (23.65 mu mol trolox equivalents per gram dry basis). Degradation kinetics of the compounds was first order; H. lactifluorum and R. flava had the highest loss of phenols and antioxidants, respectively. Conclusion: The mushrooms studied showed high nutritional value and retained more than 50 % of their antioxidant properties after thermal processing.