Torrefaction of durian peel in air and N2 atmospheres: Impact on chemical properties and optimization of energy yield using multilevel factorial design oleh Jindarat Pimsamarn, Napat Kaewtrakulchai, Awat Wisetsai, Jomthong Mualchontham, Nattawut Muidaeng, Poraphat Jiraphothikul, Chaowat Autthanit, Apiluck Eiad-Ua, Navadol Laosiripojana, Supachai Jadsadajerm