Versi Online: http://journal.ipb.ac.id/index.php/jtip DOI: 10.6066/jtip.2018.29.2.164 Hasil Penelitian J. Teknol. dan Industri Pangan Vol. 29(2): 164-174 Th. 2018 ISSN: 1979-7788 Terakreditasi Ristekdikti: 51/E/KPT/2017 164 CHANGES IN ANTIOXIDANT AND PHYSICOCHEMICAL PROPERTIES OF INDONESIAN BLACK RICE FLOUR (VAR. BANJARNEGARA AND BANTUL) DURING NO-DIE EXTRUSION COOKING [Perubahan Sifat Antioksidan dan Fisikokimia Tepung Beras Hitam Asal Indonesia (var. Banjarnegara dan Bantul) akibat Proses Pemasakan Ekstrusi tanpa Cetakan] Diana Ayu Nindita 1) , Feri Kusnandar 1,2) * and Slamet Budijanto 1,2) 1) Department of Food Science and Technology, Faculty of Agricultural Engineering and Technology, Bogor Agricultural University, Bogor 2) South East Asia Food and Agricultural Science and Technology (SEAFAST) Center, Bogor Agricultural University, Bogor Received 26 th December 2017 / Accepted 16 th October 2018 ABSTRACT This research aimed to evaluate the effect of extrusion cooking conditions (barrel temperature and feed moisture content) on the changes in the physicochemical properties and antioxidant activity of the Indonesian black rice flour (var. Banjarnegara and Bantul). The rice flours were extruded using a no-die twin screw extruder at various barrel temperatures (110 and 140°C) and moisture content of 15, 20, 25% (wb). The total phenolic content (TPC), total anthocyanin content (TAC), and antioxidant activity generally decreased by 29, 46, and 19%, respectively. During extrusion cooking, the higher moisture content re- sulted in a higher retention of anthocyanins hence increased the antioxidant activity as measured by DPPH assay. Increasing temperature produced less retention of both anthocyanins and phenolics, hence lowering the antioxidant activity. The water absorption of the products also increased as the moisture content and barrel temperature increased, while the water solubility of the products became lower as the moisture content increased. Following a no-die extrusion cooking, both varieties of the black rice experienced changes with regard to the physicochemical properties and antioxidant activity. Due to the high antioxidant activity (DPPH value of 510.4 mg Trolox equiv/100 g) and FRAP value of 2340.9 mg Trolox equiv/100 g), the black rice var. Banjarnegara is recommended for further development. No-die extrusion cooking conditions at 110 C and moisture content of more than 25% is selected to achieve fully gelatinized flour with high antioxidant activity. Keywords: anthocyanin, antioxidant properties, black rice, extrusion cooking, physicochemical properties ABSTRAK Penelitian ini bertujuan untuk mengevaluasi pengaruh pemasakan ekstrusi (suhu barel dan kadar air masukan) terhadap perubahan sifat fisikokimia dan aktivitas antioksidan dari tepung beras hitam asal Indonesia (var. Banjarnegara and Bantul). Tepung beras diekstrusi dengan ekstruder ulir ganda tanpa ce- takan pada variasi suhu barel (110 dan 140°C) dan kadar air (15, 20, 25%, basis basah). Secara umum, kandungan total fenol, total antosianin, dan aktivitas antioksidan menurun oleh pemasakan ekstrusi. Kadar air yang lebih tinggi meningkatkan retensi kerusakan antosianin, yang terlihat dari peningkatan aktivitas antioksidan yang diukur dengan DPPH assay. Peningkatan suhu barel menurunkan retensi antosianin dan fenol, sehingga menurunkan aktivitas antioksidannya. Penyerapan air pada produk juga meningkat seiring dengan kenaikan kadar air dan suhu barel, sementara kelarutan air pada produk menurun seiring dengan semakin rendahnya kadar air yang digunakan. Pada pemasakan ekstrusi, kedua varietas beras hitam Bantul and Banjarnegara mengalami perubahan sifat fisikokimia dan aktivitas antioksidan. Penggunaan beras hitam Banjarnegara yang memiliki kadar antioksidan yang lebih tinggi dibandingkan beras hitam Bantul direkomendasikan untuk dipilih. Kondisi yang sesuai adalah pemasakan ekstrusi tanpa cetakan di- atur pada suhu 110°C dan kadar air masukan lebih dari 25% untuk mencapai tepung yang tergelatinisasi secara sempurna dengan aktivitas antiosidan yang tinggi. Kata kunci: antosianin, beras hitam, pemasakan ekstrusi, sifat antioksidan, sifat fisikokimia INTRODUCTION1 Rice ( Oryza sativa L.) is one of the staple foods for more than 3 billion people in more than 100 *Corresponding Author: E-mail: fkusnandar@gmail.com countries of the world (Birla et al., 2017). Based on the bran color, rice is classified into non-pigmented rice and pigmented rice (Goufo and Trindade, 2014). Pigmented rice cultivars are reported as potent sour- ces of antioxidants and are encouraged as a functio- nal food (Reddy et al., 2016). Raw black rice has the highest antioxidant activity as it is the richest source