Physicochemical Properties of Some Improved Indonesian Red Rice Flour Varieties

Abstract

Red rice is known to be rich in antioxidants due to the presence of bioactive compounds, such as phenolics and anthocyanins in the bran layers. Therefore, this study aims to characterise the physicochemical properties of some improved red rice varieties (Aek Sibundong, Inpari 24, Inpara 7, and Inpago 7) and to evaluate the cooking effect (Nagasari, Talam, and Apem cakes processing) on its phenolic content. The varieties were dehulled, with some being partially polished for 0, 30, and 60 secs, respectively. Furthermore, the rice flour was measured for its amylose, protein, fat, ash, water, and total phenolic content (TPC), as well as pasting properties. The results showed that polishing duration reduced the protein, fat, and ash components but increased the amylose content. Also, polishing duration decreased the initial gelatinisation temperature, while the influence on the breakdown and setback viscosities had no obvious patterns. Moreover, the TPC proportionally reduced to the polishing duration. The red rice flour of 30 secs was subsequently used to make Nagasari (boiling & steaming), Talam (steaming), and Apem (baking) cakes. Due to the processing of Nagasaki and Talam cakes, the TPC of 148-211 mg/100g, significantly decreased to approximately one-third, while the preparation of Apem reduced the total phenolic content in Inpago 7, Inpara 7, and Inpari 24, to almost half, except for Aek Sibundong.