Valorization of SCG through Extraction of Phenolic Compounds and Synthesis of New Biosorbent

Abstract

Coffee is considered to be one of the most renowned beverages and it is the second-most consumed product worldwide. Spent coffee grounds (SCGs) are the primary solid residue, which are generated during the coffee powder brewing in hot water or steam. The formation of huge amounts of these byproducts poses a severe threat to the environment, due to their organic nature and their high phenolic compounds concentration. Nevertheless, the latter are characterized as bioactive compounds with high antioxidant activity turning SCG into an economical raw matrix for the isolation of valuable components. Phenolic compounds that can be isolated from coffee byproducts can be potentially used as natural antioxidants in food, pharmaceutical, and cosmetics industries. Thus, the research community has focused its efforts on the optimization of phenolics extraction by the development of novel environmentally friendly techniques except for conventional maceration extraction using organic solvents. The objective of this review is to present an inclusive summary of the revalorization of SCGs and the potential uses of those solid residues through the recovery of phenolic compounds or the use of untreated or treated SCGs as biosorbents of valuable compounds from other food industry byproducts.

A Review of the Feasibility of Producing Polylactic Acid (PLA) Polymers Using Spent Coffee Ground

“…The disposal of SCGs in water bodies can also have harmful effects. The release of nutrients from SCGs can contribute to eutrophication, harmful algal blooms, and the presence of toxic organic compounds such as caffeine and phenols, which can harm aquatic organisms [22,25,26]. When SCGs are not adequately managed and decompose, they can release methane and carbon dioxide, both of which are greenhouse gases that contribute to climate change [22].…”

Integrated Approach to Spent Coffee Grounds Valorization in Biodiesel Biorefinery

“…The presence of vitamin E and squalene could also be attractive when valorizing them from another waste stream-UM. The content of individual unsaponifiable compounds depends on the roasting process of coffee and extraction process of oil from the SCG, mainly solvent polarity and extraction temperature, as some of these compounds, such as tocopherols, cafestol, and kahweol, are thermolabile [11,19]. Despite the negative impact of UM compounds on biodiesel quality or stability, they positively affect human health, such as lowering the serum cholesterol and antioxidant activity of sterols and tocopherols [11,59], so they might be further valorized.…”

“…According to Campos-Vega et al (2015), extracted oil mainly consists of glycerides (generally up to 80-90%) with the following oil composition (% of total lipids)-84.4% of triacylglycerols, 12.3% of diterpene alcohol esters, 1.9% of sterols, 1.3% of polar compounds, and 0.1% of sterol esters [18]. Among fatty acids, the SCGO predominantly contains linoleic (C18:2) and palmitic (C16:0) acids, followed by stearic and oleic acids [19]. The obtained oil yield and composition depend on many variables, such as different brewing methods, fresh coffee type, the moisture content in the SCG, particle size, amount and polarity of the used solvent, the extraction process, and extraction time [20].…”

Liquid Hot Water (LHW) and Hydrothermal Carbonization (HTC) of Coffee Berry Waste: Kinetics, Catalysis, and Optimization for the Synthesis of Platform Chemicals

“…Efforts are being made to utilize these materials in the pig and livestock industries, beverages, vinegar, biogas, caffeine, pectins, peptic enzymes, proteins, and fertilizers [8][9][10][11]. There are several ways of coffee waste management, such as oxidation ponds [12], modular anaerobic treatment systems [13], anaerobic upflow filters [14], worm farming [15], composting [16], and hydrothermal valorization [17][18][19][20][21]. This paper will mainly focus on hydrothermal carbonization (HTC) and liquid hot water extraction (LHW).…”