<![CDATA[Bioethanol fermentation from molasses is one strategy for turning sugar-industry waste into a renewable energy source. This study designed and built an Internet of Things (IoT)-based bioethanol fermentation system integrated with temperature (DS18B20), pH (PH-4502C), CO₂ gas (MQ-135), ethanol vapor (MQ-3), pressure (HX710B), and bubble-counter (FC-03) sensors on an ESP32 module, equipped with a real-time monitoring dashboard and data-logging system. Fermentation was carried out using Saccharomyces cerevisiae at molasses concentrations of 15, 16, and 18 °Brix, with 2 g/L ammonium-sulfate (ZA) nutrient supplementation, an operating temperature of 32–36 °C, and a 48-hour fermentation time. The actual bioethanol yield reached 20.94% (efficiency 40.98%) at 16 °Brix, 20.24% (39.60%) at 15 °Brix, and 15.27% (29.89%) at 18 °Brix, even though 18 °Brix recorded the highest sugar conversion (54.80%); this discrepancy is attributed to carbon diversion toward the High-Osmolarity-Glycerol (HOG) pathway under elevated osmotic pressure. The CO₂-proxy and ethanol-estimate profiles showed qualitatively consistent trends that aligned with the early fermentation rate across variations, but were non-selective and prone to saturation, so they are valid only as trend indicators rather than absolute measurements. The optimum molasses concentration was found at 16 °Brix, providing a basis for refining IoT-based bioethanol fermentation monitoring in future work.]]>
