Evaluation of the Physico-chemical and Biological Properties of Fermented Nipa (Nypa fruticans) Sap Under Closed and Open Vessel Fermentation System for Bioethanol Production

Background The potential of Nipa ( Nypa fruticans ) sap in the Cagayan Region, Philippines, for bioethanol production remains largely underexplored despite its vast expanse. Methods This study investigates the key physico-chemical properties of Nipa sap from Aparri, Cagayan, with a focus on fermentation dynamics and storage conditions to optimize ethanol production. Two fermentation treatments closed and open vessel conditions, were compared to determine the optimal conditions for maximum ethanol yield. Over a 7-day fermentation period, the acetic acid production, yeast activity, sugar content, and ethanol concentration of closed vessel fermented sap (CVFS) and open vessel fermented sap (OVFS) were monitored. Results CVFS demonstrated a higher ethanol yield (7.56%v/v at peak day), characterized by minimized acetic acid accumulation and stable yeast activity. In contrast, OVFS exhibited significant fluctuations in acetic acid and ethanol levels, indicating a lower fermentation efficiency. Conclusion The presence of methanol and high acetic acid content in open-vessel fermentation systems highlights the importance of fermentation conditions to prevent impurities. This study provides valuable insights into optimizing ethanol production from fermenting Nipa sap by employing closed vessel fermentation, which is crucial for sustainable bioethanol production in the Cagayan region.