Spent coffee grounds (SCGs) generated in coffee processing for beverages and other products are a very significant organic residue that needs to be properly treated. Waste valorization via oil extraction has the potential to obtain compounds that can be used for producing biodiesel or other high-value products, such as polymers. This work focuses on the ultrasound-assisted extraction of SCG oil using n-hexane as a solvent. Three key process parameters are analyzed: temperature, extraction time, and liquid/solid (L/S) rate of solvent, using a central composite rotatable design (CCRD), an analysis that, to the author’s knowledge, is not yet available in the literature. The data were analyzed using the software StatSoft STATISTICA 13.1 (TIBCO Software Inc., Palo Alto, CA, USA). Results show that all parameters have a statistical influence on the process performance (p < 0.05), being the L/S ratio the most significant, followed by extraction time and temperature. An analysis of variance (ANOVA) showed that the empirical model is a good fit to the experimental data at a 95% confidence level. For the range of conditions considered in this work, the optimal operating conditions for obtaining an oil extraction yield in the range of 12 to 13%wt are a solvent L/S ratio of around 16 mL g−1, for a temperature in the range of 50 to 60 °C, and the longest contact time, limited by the process economics and health and safety issues and also, by the n-hexane boiling temperature.

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For the first time, specimens of Holothuria impatiens are reported from the Tunisian coast, supported by molecular (COI sequencing) and morphological (examination of ossicles) analyses. For comparative purposes, Holothuria impatiens samples were genetically analyzed with existing data from Spain, Italy, and the Red Sea. In addition to their external morphology, an external substance covering the individuals is described, besides the new ossicle structure described in the body wall of H. impatiens samples. The results of the morphometry of the specimens from the Tunisian coast revealed that, for two shapes of ossicles, the size of the individuals does not influence their structures. Low genetic diversity was observed in Tunisia, with two haplotypes; one of both haplotypes was reported for the first time exclusively in Tunisia. The phylogenetic tree showed that the haplotypes were shared across all locations, revealing that the Mediterranean and Red Sea individuals were clearly distinct. Further studies on the genetic diversity of H. impatiens are crucial for the evaluation of the singularity of Mediterranean populations.