The study, conducted by a team at Universitas Jambi and published in Heliyon, set out to answer a provocative question: could the biochemical magic of civet coffee, the famously expensive brew produced when beans pass through the digestive tract of the Asian palm civet, be replicated in a sterile glass bottle without any animal involvement? Civet coffee owes its character partly to microbes living in the animal’s small intestine and cecum, where genera such as Lactobacillus and Leuconostoc help break down complex compounds in the bean. The Indonesian team reasoned that if those same bacterial players could be deployed deliberately, the result might be a consistent, scalable, and ethically uncontroversial alternative to the civet pipeline.

To test the idea, the researchers obtained grade A green Liberica beans grown by a peatland coffee producer in West Tanjung Jabung and inoculated one-kilogram batches in sealed dark glass bottles with starter cultures of Lactiplantibacillus plantarum and Leuconostoc mesenteroides, both supplied by Indonesia’s National Research and Innovation Agency. The two organisms were chosen for their complementary metabolisms. L. plantarum is homofermentative, converting sugars almost exclusively into lactic acid, while L. mesenteroides is heterofermentative, generating acetic acid, ethanol, and carbon dioxide alongside lactic acid. Beans were submerged in nutrient broth, fermented anaerobically for either 48 or 72 hours, shaken every 12 hours, then washed, sun-dried, and roasted at 200 degrees Celsius for three to five minutes. Six treatment combinations emerged: each bacterium alone at each duration, plus both together at each duration.

Throughout fermentation, the team tracked pH at 12-hour intervals and watched it fall steadily, a sign that the bacteria were metabolizing fermentable sugars in the coffee mucilage and accumulating organic acids. That acidification matters, because it shapes the chemical environment in which flavor precursors form. When the roasted beans were finally analyzed, the differences were striking. Total phenolic content rose from 42.271 milligrams of gallic acid equivalents per gram in the unfermented control to as high as 53.833 in beans fermented for 72 hours with the mixed culture, while antioxidant activity, measured by the DPPH assay, improved dramatically. The unfermented coffee needed 72.122 micrograms per milliliter to quench half of the free radicals in the test, whereas the best fermented samples required barely 3 to 5 micrograms, an order-of-magnitude gain in radical-scavenging power.

Not every biochemical change moved in the same direction. Total flavonoid content actually peaked in the shortest, single-culture treatment, reaching 12.946 milligrams of quercetin equivalents per gram after 48 hours with L. plantarum alone, then declined in longer and mixed fermentations. The authors attribute this to bacterial beta-glucosidase enzymes, which cleave flavonoid glycosides into simpler metabolites. Caffeine, meanwhile, told perhaps the most commercially intriguing story. The unfermented beans contained 0.858 micrograms per milliliter of caffeine, but levels fell progressively with fermentation time and microbial load, bottoming out at just 0.117 micrograms per milliliter in the 72-hour mixed-culture sample. Microbes are known to demethylate caffeine, a purine alkaloid, into intermediates such as paraxanthine and methylxanthines that they can then consume as carbon and nitrogen sources, and the study suggests a similar pathway may be at work here.

Chlorogenic acid, the polyphenol largely responsible for coffee’s acidity, bitterness, and antioxidant reputation, proved far more stubborn. Across all treatments its concentration hovered between roughly 3.67 and 3.73 micrograms per milliliter, with no statistically meaningful decline. The ester bonds linking caffeic and quinic acid in the chlorogenic acid molecule appear resistant to the mild conditions of this fermentation, meaning the process can strip out caffeine without sacrificing one of coffee’s most valued bioactive compounds, a combination that low-caffeine, high-antioxidant product developers may find hard to ignore.

Proximate analysis added further nuance. Moisture content rose in most fermented samples but stayed well within the 12.5 percent ceiling accepted by Indonesian, International Coffee Organization, and Specialty Coffee Association standards, so shelf stability was not compromised. Ash and lipid contents barely moved, indicating that minerals and fats survived the microbial onslaught largely intact. Protein content, however, shifted noticeably, spiking to 32.14 percent in the 48-hour mixed-culture sample, and carbohydrate content dropped in every fermented batch as the bacteria consumed glucose and sucrose for energy. That carbohydrate depletion is not a loss but a transformation: the sugars that once sat inert in the bean have been converted into organic acids and other metabolites that will later feed the Maillard reactions responsible for roasted coffee’s aroma.

The sensory verdict came from three certified panelists at the Indonesian Coffee and Cacao Research Institute, who cupped the samples blind under Specialty Coffee Association protocols, scoring ten attributes from fragrance to overall impression. Every fermented sample outperformed the control, and the mixed cultures dominated. The 72-hour co-fermentation earned perfect tens for sweetness, uniformity, and clean cup, and its final score of 87.57 placed it firmly in the excellent category reserved for scores between 80 and 90. Descriptors shifted from the control’s bright citrus, baked, and caramel notes toward berry, grape, nutty, peach, and juicy profiles in the mixed-culture beans, with the L. plantarum treatments leaning toward berries, malic acid, and sweet orange, and the L. mesenteroides treatments toward tamarind, lime, red apple, and mango.

The chemistry behind those flavors likely reflects microbial synergy. In mixed culture, the two lactic acid bacteria occupy complementary metabolic niches, each contributing distinct metabolites that shape acidity, sweetness, and aroma, while their combined activity suppresses undesirable microorganisms and sustains fermentation across different stages. Gas chromatography-mass spectrometry confirmed that lipid-derived esters dominated the solvent-extractable profile of all samples, with compounds such as glyceryl trilaurate and hexadecanoic acid esters persisting throughout, while fermentation-specific products like vinyl laurate and 2-lauro-1,3-didecoin appeared only in treated beans. The authors are careful to note that this solvent-based extraction captures extractable constituents rather than the full aroma-active fraction of brewed coffee, and that headspace techniques such as HS-SPME-GC-MS would be needed to fully map the volatile landscape.

The implications stretch well beyond a single Indonesian province. Liberica’s tolerance of degraded peat soils makes it a rare crop that can support farmer livelihoods in landscapes where Arabica and Robusta simply fail, giving it a potential role in both peatland conservation and climate adaptation. If a simple, food-safe bacterial starter can reliably lift its cup quality into specialty territory while simultaneously lowering caffeine and boosting antioxidant activity, the economics of an entire neglected coffee species could change. The researchers caution that their work examined only strain selection and duration, leaving fermentation kinetics, microbial community dynamics, and metabolite mechanisms for future study. But the core finding stands: two of the food industry’s most familiar bacteria, working together in a sealed bottle, can accomplish what was once thought to require a civet’s gut, and they can do it with precision, consistency, and a cupping score that would turn heads at any specialty coffee competition.

Subject of Research: Controlled lactic acid bacterial fermentation of Liberica coffee beans and its effects on sensory quality, antioxidant activity, and chemical composition

Article Title: Effect of fermentation on the quality of Liberica coffee ( Coffea liberica ) using Lactiplantibacillus plantarum and Leuconostoc mesenteroides bacteria: Sensory analysis, volatile compound, antioxidant, and proximate analysis

Article References: Tarigan, I. L., Ramadhan, I. I., Latief, M., Febrianto, N. A., & Sutrisno (2026). Effect of fermentation on the quality of Liberica coffee (Coffea liberica) using Lactiplantibacillus plantarum and Leuconostoc mesenteroides bacteria: Sensory analysis, volatile compound, antioxidant, and proximate analysis. Heliyon, 12(15), Article e45531. https://doi.org/10.1016/j.heliyon.2026.e45531

Image Credits: AI Generated

DOI: 10.1016/j.heliyon.2026.e45531

Keywords: Liberica coffee, coffee fermentation, lactic acid bacteria, Lactiplantibacillus plantarum, Leuconostoc mesenteroides, antioxidant activity, caffeine reduction, sensory analysis, SCA cupping, volatile compounds, peatland agriculture, Indonesia