Effect of Die Temperature and Porang (Amorphophallus mulleri B.) Flour on the Physicochemical Properties, Nutritional Value, Estimated Glycemic Index, and Sensory Evaluation of Brown Rice Snack by a Collet Extruder

Porang is an underutilized Indonesian tuber plant that exhibits potential as an ingredient in extrusion-based snacks. This study aims to develop brown rice snacks incorporating porang flour at various die temperatures using a collet extruder to enhance their physicochemical properties. The collet extruder used in this study is a cost-effective method for installation, maintenance, and operation. The effect of die temperature (90, 100, and 110 °C) and porang (0, 5, 15, and 25 %) as independent variables were studied on the physicochemical properties, nutritional value, and sensory evaluation of extrudates. According to the experimental results, higher die temperatures significantly (p < 0.05) increased ash content (1.33 - 2.11 %), crude fat (0.91 - 2.05 %), a* value (0.96 - 4.98), water absorption index (WAI) (5.84 - 9.27 g/g),water solubility index (WSI) (6.64 - 16.05 %), DPPH free radical scavenging ability (8.14 - 18.53 %), total phenolic content (TPC) (200.61 - 426.93 mg GAE/100g d.m.), and total flavonoid content (TFC) (407.20 - 1661.11 mg RE/100 g d.m.); decreased crude protein (9.85 – 7.11%), and L* value (82.37 - 69.25). The extrudate produced at 100 °C had the highest radial expansion ratio (1.57 – 2.79 mm/mm); lowest bulk density (0.21 - 0.14 g/cm3) and hardness (2.39 - 1.30 kgf). The increased addition of porang flour significantly increased (p < 0.05) moisture content (2.01 – 2.62 %), ash content, total carbohydrate (84.83 – 86.83 %), a* value, b* value (11.80 – 16.65), bulk density, hardness, WAI, WSI, DPPH free radical scavenging ability, TPC, and TFC, whereas decreased the crude protein, crude fat, L* value, radial expansion ratio. According to the sensory evaluation results, consumers preferred the extrudates with 5 % porang flour processed at a die temperature of 110 °C over the other extrudates. Incorporating porang flour into puffed snacks could serve as a potential component in developing snacks that meet consumer demand for nutritionally beneficial products because of its low glycemic index (40.604 - 44.789). Snacks made with porang flour could provide beneficial effects for both healthy individuals and those with health concerns, making them suitable for a wide range of consumers.