Coffee pulp, a by-product of coffee production, contains valuable compounds such as caffeine and chlorogenic acid with high antiradical activity. In this study, aqueous solutions of β-cyclodextrin (β-CD) were used as a non-conventional solvent for the extraction of targeted compounds from coffee pulp. The parameters of β-CD concentration (C_βcd), liquid-to-solid ratio (L/S), and temperature (T) were evaluated based on the antiradical activity (A_AR) and the caffeine content (C_Caf). The optimum operational conditions were found to be C_βcd: 9.25 mg/mL, L/S: 30 mL/g and T: 80 °C. The sensory profiles of brews prepared with coffee and coffee pulp with or without cyclodextrin were studied with quantitative descriptive analysis. The brew from the by-product had fruity, botanic, sweet and sourness sensory properties, and cyclodextrin was found to be able to affect the overall taste of the brew.

In the present study, cold atmospheric plasma (CAP) was employed as a pretreatment method for the extraction of phenolic compounds from spent coffee grounds (SCGs). The impact of CAP treatment conditions, i.e., thickness of the SCGs layer (mm), distance between the plasma source and the SCGs layer (mm) and duration of CAP treatment (min), on the total phenol content, in vitro antioxidant activity, as well as caffeine and chlorogenic acid content of SCGs, was investigated. The process parameters were optimized with the aid of response surface methodology (RSM). After optimizing the CAP pretreatment conditions, the CAP-treated SCGs were subjected to ultrasound-assisted extraction using ethanol as the extraction solvent. The optimum conditions for CAP treatment identified, i.e., thickness, 1 mm; distance, 16 mm; and duration, 15 min, led to a significant enhancement in the recovery of bioactive compounds from SCGs compared to those obtained from untreated SCGs. Total phenolic content and antioxidant activity significantly increased (i.e., TPC from 19.0 ± 0.7 to 24.9 ± 1.4 mg GAE/100 g dry SCGs, A_DPPH from 106.7 ± 5.01 to 112.3 ± 4.3 μmol Trolox/100 g dry SCGs, A_ABTS from 106.7 ± 5.01 to 197.6 ± 5.8 μmol Trolox/100 g dry SCGs, A_CUPRAC from 17938 ± 157 to 18299 ± 615 μmol Trolox/100 g dry SCGs). A significant increase in caffeine content from 799.1 ± 65.1 mg to 1064 ± 25 mg/100 g dry SCGs and chlorogenic acid content from 79.7 ± 15.3 mg to 111.3 ± 3.3 mg/100 g dry SCGs, was also observed. Overall, CAP pre-treatment can be used to enhance the recovery of bioactive compounds from SCGs.

Spent coffee grounds (SCG), a solid by-product generated during coffee preparation, are produced in substantial quantities yet remain largely underexploited. The valorization of SCG offers significant environmental, economic, and social advantages, contributing to the advancement of a circular bioeconomy. In this study, SCG valorization consisted of two steps. In the first step, the SCG was depleted by supercritical CO₂ at 250 bar for 4 h, and by using two different temperatures: 40 °C and 60 °C. In the second step, the defatted SCG was subjected to subcritical water extraction at different temperatures, and ultrasound-assisted extraction at both different amplitudes and temperatures. The objective of this study was to evaluate a sequential extraction approach for the recovery of fatty acid methyl esters (FAMEs) and the subsequent maximization of caffeine extraction from SCG. The FAME profile was determined in ten supercritical fluid extracts and two Soxhlet extracts, while caffeine content was evaluated in five subcritical water extracts and six ultrasound-assisted extracts obtained from SCG, previously exhausted by supercritical CO₂ extraction. The highest caffeine content was present in a subcritical extract obtained at 180 °C, while the most abundant fatty acids found in all the tested extracts were linoleic acid (43.79–54.15%) and palmitic acid (32.73–45.85%). The predominance of linoleic and palmitic acids in the obtained extracts suggests their potential application as feedstocks for biodiesel production and oleochemical industries. Furthermore, the high content of linoleic acid, an essential polyunsaturated fatty acid, may enhance the value of these extracts for cosmetic and nutraceutical applications.