PENGARUH JENIS DAN KONSENTRASI BAHAN PENCEGAH PENCOKELATAN TERHADAP KARAKTERISTIK FISIKOKIMIA DAN FUNGSIONAL TEPUNG UBI JALAR UNGU (The Effect of Type and Concentration of Browning Inhibitor Agent on Physicochemical and Functional Characteristics of Purpl - Munthe, Lusiana (Universitas Sumatera Utara, 2019)