Design, Fabrication and Thermal Evaluation of Lemang (Rice Bamboo) Cooking Device Integrated with Continuous Rotating System

Abstract

Lemang is one of the typical Malay food made from white glutinous rice and is cooked inside a bamboo stalk cavity using a direct open fire method. An existing cooking technique is still using manual methods especially for turning the bamboo so it becomes harmful for hand. This research aims to design, fabricate and evaluate a lemang rice cooking device integrated with a continuous rotating system. The methods used in this study were: 1) functional analysis of the design, 2) structural analysis of the design using computer-aided design (CAD), 3) manufacturing a prototype, 4) testing and evaluating the cooking device. Performance evaluation was conducted for observing heat distribution in bamboo and specific energy consumption during the cooking process. The results show that the power requirement of the rotating system was 0.5 hp and the rotation speed of lemang bamboo was 15 rpm. The overall dimension of the device is 2140 × 920 × 980 mm with a cooking capacity of 36 lemang per batch. The heating performance was analyzed using ANOVA. The result reveals that there was no significant temperature difference between all positions of the bamboo surface during the cooking process (fairly uniform) as the impact of using a continuous rotating system. Furthermore, the specific energy consumption was 145.72 MJ/kg dry glutinous rice and cooking time was 2 hours. By using this cooking device, operators do not necessarily use their hand to turn bamboo while the cooking process occurred so the process will run safely.