Nur Nabilah Athirah Ahmad Juhairimi, Nuur Amalina Syahida Md Radzi, Nurul Alia Faqihah Hanafi, 

and Noraziah Abu Yazid

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INFLUENCE OF MOISTURE CONTENT AND CALCIUM CARBONATE CONCENTRATION ON LACTIC ACID PRODUCTION FROM OIL PALM EMPTY FRUIT BUNCH VIA SOLID-STATE FERMENTATION 

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Abstract 

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Rising demand for biodegradable polymers such as polylactic acid (PLA) has increased interest in cost-effective lactic acid production from low-cost, renewable feedstocks over costly conventional substrates. Lignocellulosic biomass such as oil palm empty fruit bunch (OPEFB) is an abundant, renewable substrate for lactic acid bacteria in solid-state fermentation (SSF). Moisture content and calcium carbonate (CaCO₃) concentration were selected as study variables because moisture governs substrate water activity and mass/oxygen transfer, while CaCO₃ governs buffering capacity and pH stability during lactic acid accumulation, which are factors not previously investigated for OPEFB. This study examines, on a one-factor-at-a-time (OFAT) basis, the effects of moisture content (71–91% w/w) and CaCO₃ concentration (0–80% w/w) on lactic acid production from untreated OPEFB via SSF using Lactobacillus casei. Fermentation ran at 37°C for 5 days, with OPEFB supplemented with ammonium chloride and yeast extract. The highest lactic acid concentration (8.08 mg g⁻¹) and yield (0.1911 g g⁻¹) occurred at 76% moisture content, and the highest CaCO₃ treatment concentration (6.64 mg g⁻¹) at 50% (w/w) CaCO₃. These values are modest relative to literature reports for lignocellulosic lactic acid production, a hydrolysis pretreatment step is recommended for future work. This study demonstrates the feasibility of untreated OPEFB as a low-cost lactic acid feedstock and is among the few SSF studies on OPEFB reporting single-factor baseline data for moisture content and CaCO₃ concentration, laying groundwork for future process development toward biodegradable polymers.

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