Effects of Pretreatment on the Extraction Efficiency of Carbohydrate from Spent Coffee Ground

Chong, Ching Yee (2018) Effects of Pretreatment on the Extraction Efficiency of Carbohydrate from Spent Coffee Ground. Final Year Project (Bachelor), Tunku Abdul Rahman University College.

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Abstract

SCG, Spent Coffee Ground is the coffee residue left after coffee brewing. Considering the large amount of waste generated from the coffee industry, the potential of this by-product was intensively studied researchers. In this study, different pretreatments were conducted to increase the yield of carbohydrates from SCG. Three pretreatments, included roasting, steam, and cellulase enzyme were conducted in this study. Then, the pretreated SCG was further extracted with NaOH to produce insoluble residues and soluble extracts. The effects of different pretreatments on the chemical and functional properties of SCG insoluble residues and the antioxidant properties of the soluble extract were determined. The insoluble residue was characterized based on its water and oil holding capacity, whereas antioxidant property of the soluble extract was determined through DPPH test and FRAP assay. Total carbohydrate content in the SCG soluble extract was determined through Dubois test. The results of this study revealed that, extraction of enzyme pretreated SCG (6 hours, 3% w/v cellulase enzyme) produce the highest carbohydrates yield (59%) compared to the roasted (42%) and steam pretreated (41%) SCG. Only about 36% of carbohydrates were successfully extracted from the untreated SCG. Moreover, the 24 hours enzyme pretreatment with 1% w/v of enzyme was also improved the water and oil holding capacity of SCG insoluble residues from 5.178 ± 0.191 g/g and 3.769 ± 0.129 g/g to 7.004 ± 0.127 g/g and 4.758 ± 0.205 g/g respectively. While, the soluble extracts of roasted SCG (50°C for 1 hour) had been found to possesses the highest scavenging activity (34.986 ± 1.67 ppm AEAC at 100 dilution). The soluble extracts of roasted SCG at 50°C for 3 hours had been found to possesses the highest reducing power (404.458 ± 4.73 μM FSE/g) compared to the untreated SCG (358.625 ± 3.75 μM FSE/g). According to the results of Dubois test, soluble extract of enzyme pretreated SCG with 3% w/v enzyme for 6 hours had been found to contain the highest total sugars content (7.89 ± 1.07 g/L at 100 dilution). The soluble extract of untreated SCG was found contained 5.12 ± 2.87 g/L (100 dilution factor).