Valorization of coffee bean processing waste for the sustainable extraction of biologically active pectin
G. Divyashri, T. P. Krishna Murthy, K.V. Ragavan, Gangadhar Mugulurmutt Sumukh, Lingam Sadananda Sudha, Srikanth Nishka, Gupta Himanshi, Nafisa Misriya, B. Sharada, Anjanapura V. Raghu
Abstract
The dry method of coffee processing generates a significant amount of coffee husk, an agricultural waste for which currently there is a lack of profitable use, and their disposal constitutes a major environmental problem. Pectin was extracted from coffee husk using citric acid solution (pH 1.5) by microwave-assisted extraction method, followed by using ice-cold ethanol. The coffee husk pectin (CHP) with a yield of 40.2% was characterized using SEM, FT-IR, and XRD techniques. The CHP exhibited significant in-vitro antioxidant activity as measured by using 2,2-diphenyl-1-picrylhydrazyl; (IC 50 value of 395.1 ± 0.42 μg/mL), ferrous reducing antioxidant capacity (A 700 nm = 0.55 ± 0.08), 2,2′-Azino-bis (3-ethylbenzothiazoline-6-sulfonic acid) radical scavenging (42.02 ± 0.38%) and ascorbic acid auto-oxidation inhibition (92.01 ± 0.28%) assays. CHP demonstrated antibacterial activity against Escherichia coli and Bacillus cereus with an inhibition diameter of 20 ± 1.01 mm and 18 ± 0.84 mm, respectively. Interestingly, CHP showed a significant anti-inflammatory effect by negatively modulating the expressions of TNF-α and TGF- β in LPS-stimulated macrophage cell lines. Collectively, our findings suggest that the coffee husk is a potential source of commercial pectin, microwave-assisted extraction has a great potency on the commercial pectin extraction from the coffee husk and CHP demonstrates significant biological activity.