Exploring value-adding components from different varieties of arabica coffee pulps for sustainable resource utilisation

Coffee processing produces substantial agricultural byproducts, notably pulp, which is known to harbour valuable bioactive compounds. Nevertheless, a considerable knowledge gap remains concerning the phyto-compositions of the extracts from the diverse arabica varieties grown in northern Thailand. This study aimed to characterise value-adding components from the pulps of eight arabica coffee varieties by assessing their proximate compositions, phytochemical profiles, and mineral contents. Subsequently, the pectin characterisation was evaluated. Coffee pulp's primary constituents are carbohydrates, crude fibre, and protein, with a relatively low-fat and ash content. Specifically, the Catimor progeny P88 (P88) variety had the highest carbohydrate content (67.77% ± 0.09), while Catuai had the highest crude fibre (19.42% ± 0.41), and Catimor H528R (H528R) contained the maximum protein (15.41% ± 0.22). The P88 variety also proved to be a superior source of phytochemicals, exhibiting the highest levels of total phenolics (6.41 ± 0.04 mgGAE/gDW) and flavonoids (10.28 ± 1.14 mgCE/gDW), which corresponded to the strongest antioxidant activity in DPPH (88.81% ± 1.22), and ABTS (88.80% ± 0.00) assays. In terms of mineral content, the H528R, Bourbon Phanokkok, and Catimor progeny 90 varieties showed the highest overall levels, suggesting they are good sources of phosphorus, magnesium, and potassium. Analysis of the extracted pectin revealed that all samples were high-methoxyl pectin, with a degree of esterification (DE) exceeding 50%. The findings of this study indicate that arabica coffee pulp is an abundant source of beneficial bioactive substances and shows promise as a raw material for producing high-grade pectin for food manufacturing. These results represent an initial step toward valorisation, with further research required to explore potential applications and commercial uses.