Different novel extraction techniques on chemical and functional properties of sugar extracts from spent coffee grounds

Large amounts of solid wastes such as spent coffee grounds (SCGs) from brewing provide a valuable sugar source to investigate. The effects on the sugar properties of extraction factors were studied. Different solvent extractions using an autoclave showed distinguishable sugar contents and properties. Water extracted the highest total sugar content while alkali extracted the highest total phenolic content (TPC). The ultrasonic-water-bath-assisted extraction with water did not produce any significant content or TPC. Finally, the combination of ultrasonic-autoclave-assisted extraction with water at 40% amplitude for 10 min produced the highest total sugar content and TPC, similar to that found in samples from the autoclave extraction with water. The FT-IR spectra of SCGs sugar revealed both amorphous and crystalline structures. All sugar extracts from SCGs contained phosphorus, potassium and calcium as the main mineral elements. Thus, sugar extracts from SCGs can be considered as an alternative additive with a good TPC for food products.