Synthesis of melanoidin-like polymers for non-roasted coffee brewing

Abstract

Here, a mushroom oxidase-based transformation is exploited to polymerize green coffee bean polyphenols at room temperature, leading to the formation of melanoidin-like polymers. Component analyses of the enzymatic reactions reveal that low-molecular-weight polyphenols in hot water extracts of green coffee beans are selectively involved in the polymerization, thus giving rise to polyphenolic polymers. A model experiment employing laccase, chlorogenic acid, and pectin also demonstrates that enzymatic polymerization further entangles green coffee polysaccharides, thereby mimicking the polyphenolic and carbohydrate moieties of roasted coffee melanoidins. Carcinogenic acrylamide, which is detected in roasted coffee at ppb levels (i.e., 43.58 +/- 7.89 ng/L), is found to be non-detectable in the enzymatic reactions. Additionally, the enzymatic coffee exhibits up to fourfold lower in vitro cytotoxicity, fivefold higher amylase inhibitory activity, and 10 % greater weight loss in mice compared to roasted coffee. Electronic tongue and volatile profiling analyses, which show patterns distinct from conventional coffee brewing methods, indicate that our enzyme-processed coffee provides a unique taste and aroma.