Potential Uses of Spent Coffee Grounds in the Food Industry

Abstract

Current estimates place the amount of spent coffee grounds annually generated worldwide in the 6 million ton figure, with the sources of spent coffee grounds being classified as domestic (i.e., household), commercial (i.e., coffee houses, cafeterias and restaurants), and industrial (i.e., soluble and instant coffee industries). The majority of the produced spent coffee grounds are currently being inappropriately destined for landfills or to a form of energy recovery (e.g., incineration) as a refuse-derived fuel. The disposal of spent coffee in landfills allows for its anaerobic degradation with consequent generation and emission of aggressive greenhouse gases such as methane and CO2, and energy recovery processes must be considered an end-of-life stage in the lifecycle of spent coffee grounds, as a way of delaying CO2 emissions and of avoiding emissions of toxic organic volatile compounds generated during combustion of this type of waste. Aside from these environmental issues, an aspect that should be considered is the inappropriate disposal of a product (SCG) that presents unique thermo-mechanical properties and textural characteristics and that is rich in a diversity of classes of compounds, such as polysaccharides, proteins, phenolics, lipids and alkaloids, which could be recovered and used in a diversity of applications, including food-related ones. Therefore, researchers worldwide are invested in studying a variety of possible applications for spent coffee grounds and products thereof, including (but not limited to) biofuels, catalysts, cosmetics, composite materials, feed and food ingredients. Hence, the aim of this essay was to present a comprehensive review of the recent literature on the proposals for utilization of spent coffee grounds in food-related applications, with focus on chemical composition of spent coffee, recovery of bioactive compounds, use as food ingredients and as components in the manufacture of composite materials that can be used in food applications, such as packaging.

Spent Coffee Grounds Valorization in Biorefinery Context to Obtain Valuable Products Using Different Extraction Approaches and Solvents

“…By changing the ratio of the ethanol/water mixture as the extraction solvent, it is possible to separate a wide range of compounds. When using pure ethanol, it is predominantly lipophilic compounds that are separated, while by increasing the water content in the solvent, more phenolic type compounds can be obtained [ 18 , 24 ].…”

The Potential of Spent Coffee Grounds in Functional Food Development

“…The production of food additives is a growing industry that turns over close to USD 45 billion a year [ 65 ]. SCG have been used in the preparation of baked products such as cookies and cakes as well as the production of beverages including alcoholic beverages [ 66 ]. Cookies prepared using SCG showed presence of caffeine, phenolic acids and polyphenols such as CGA [ 63 ].…”

“…Further, CGA extracts from coffee have been used in fried doughnuts, soymilk, wheat bread, liquid Khask, dark chocolate, yogurt and even instant coffee, which may increase the health benefits of these foods [ 67 ]. Increasing attention towards using coffee waste as a food additive will help to provide sustainable economic options to coffee farmers and reduce environmental impacts [ 66 , 68 ].…”

Recent Research Advancements of Coffee Quality Detection: Targeted Analyses vs. Nontargeted Fingerprinting and Related Issues

“…Besides its wide acceptance, a series of recent studies also indicated that cofee has a great inhibitory efect on obesity, diabetes [4], Alzheimer's disease [5], cardiovascular disease, infammation, cancer, and other chronic diseases [6]. Due to its excellent bioactivities, some by-products of cofee have been utilized in cosmetics, pharmaceutics, and other sectors [7,8] to replace some plant-derived extracts [9][10][11]. In particular, spent cofee grounds (SCG) present signifcant antioxidant activity and can become a prospective environmental source, which reveals their valorization in the latest studies [12][13][14].…”