**5. Patents**

The optimized method for JF treatment and stabilization described in this manuscript is part of the European Patent EP 3763224, deposited on 2020 [40].

**Supplementary Materials:** The following supporting information can be downloaded at: https: //www.mdpi.com/article/10.3390/foods11172697/s1, Figure S1. *Rhizostoma pulmo* jellyfish products obtained by the new proposed method. Ca-Citrate JF-DW: JF after treatment with calcium citrate brine; Ca-Lactate JF-DW: JF after treatment with calcium lactate brine; Salt-Alum JF-DW: JF obtained by the salt–alum-based traditional method. Figure S2. Proteins content (a) and Antioxidant activity (b) in *Cotylorhiza tuberculata*, *Rhopilema nomadica* and *Phyllorhiza punctata* JF-DW samples and the corresponding calcium salt treated samples (Ca-Lactate JF-DW and Ca-Citrate JF-DW). Protein contents were expressed as mg per 100 g of fresh weight (mg/100 g FW) and antioxidant activity was expressed as nmol TE per gram of FW (nmol TE/g FW). Values are the means of three independent measurements, ±standard deviation. ANOVA statistic test followed by Bonferroni's multiple comparison post-hoc test was used to compare each treatment with the others for each JF species. Table S1. Microbiological analyses of JF-DW (JF transported on lab and pre-treated with drinking water) untreated and treated with brines containing different calcium salts at 5 days treatment at 4 ◦C (Ca-Citrate: calcium citrate; Ca-Lactate: calcium lactate). The different letters in line indicate significant differences between samples (*p* < 0.05). TBC: total bacterial count at 30 ◦C; sCMA: saline Corn Meal Agar; sSDA: saline Sabouraud Dextrose Agar. Table S2. Microbiological analyses of JF-B (JF directly pre-treated on boat) untreated and treated with brines containing different calcium salts at 5 days treatment at 4 ◦C (Ca-Citrate: calcium citrate; Ca-Lactate: calcium lactate). The different letters in line indicate significant differences between samples (*p* < 0.05). TBC: total bacterial count at 30 ◦C; sCMA: saline Corn Meal Agar; sSDA: saline Sabouraud Dextrose Agar. Table S3. Microbiological analyses of *Rhizostoma pulmo* JF sample washed in drinking water and then treated with NaCl-alum (Salt-Alum

JF-DW). This sample was obtained after 20 days at 4 ◦C and 2 days air drying (as described in Material and Methods section). TBC: total bacterial count at 30 ◦C; sCMA: saline Corn Meal Agar; sSDA: saline Sabouraud Dextrose Agar. Table S4. Amino acid composition of *Rhizostoma pulmo* JF fresh and untreated (Untreated JF), washed in drinking water (JF-DW), and treated with calcium citrate (Ca-Citrate JF-DW) and calcium lactate (Ca-Lactate JF-DW). Data are mean ± Standard deviation (±SD) of four independent analyses. AA. amino acids; Nd. Not detected. Table S5. Microbiological analyses of *Cotylorhiza tuberculata* JF sample washed with drinking water (JF-DW) and treated with brines containing calcium salts (Ca-Citrate: calcium citrate; Ca-Lactate: calcium lactate). The different letters in line indicate significant differences between samples (*p* < 0.05). TBC: total bacterial count at 30 ◦C; sCMA: saline Corn Meal Agar; sSDA: saline Sabouraud Dextrose Agar. Table S6. Microbiological analyses of *Rhopilema nomadica* JF sample washed with drinking water (JF-DW) and treated with brines containing calcium salts (Ca-Citrate: calcium citrate; Ca-Lactate: calcium lactate). The different letters in line indicate significant differences between samples (*p* < 0.05). TBC: total bacterial count at 30 ◦C; sCMA: saline Corn Meal Agar; sSDA: saline Sabouraud Dextrose Agar. Table S7. Microbiological analyses of *Phyllorhiza punctata* JF sample washed with drinking water (JF-DW) and treated with brines containing calcium salts (Ca-Citrate: calcium citrate; Ca-Lactate: calcium lactate). The different letters in line indicate significant differences between samples (*p* < 0.05). TBC: total bacterial count at 30 ◦C; sCMA: saline Corn Meal Agar; sSDA: saline Sabouraud Dextrose Agar. Table S8. Texture, salinity and pH values of *Cotylorhiza tuberculata*. *Rhopilema nomadica* and *Phyllorhiza punctata* JF samples washed with drinking water (JF-DW) and treated with brines containing calcium salts at 5 days treatment (Ca-Citrate: calcium citrate; Ca-Lactate: calcium lactate). The different letters in line indicate significant differences between samples (*p* < 0.05). Table S9. Comparison of the fatty acid composition of and *Rhopilema nomadica*. *Phylloriza punctata* and *Cothyloriza tuberculata* JF samples washed with drinking water (JF-DW) and treated with brines containing calcium salts at 5 days treatment (Ca-Citrate: calcium citrate; Ca-Lactate: calcium lactate). Fatty acid composition data are expressed as percentage of the total fatty acids ± SD.

**Author Contributions:** Conceptualization, G.B. and A.L.; methodology, F.A.R., G.B., S.D.D., A.L., D.M., R.S. and K.K.; validation, F.A.R. and S.D.D.; investigation, F.A.R., G.B., S.D.D. and A.L.; data curation, F.A.R. and S.D.D.; writing—original draft preparation, G.B., S.D.D. and A.L.; writing— review and editing, G.B., A.L., F.P.F. and D.L.A.; funding acquisition, A.L. All authors have read and agreed to the published version of the manuscript.

**Funding:** This research was funded by the European Commission, H2020 program, Research and Innovation Action Project "GoJelly—A gelatinous solution to plastic pollution", gran<sup>t</sup> number 774499. S.D.D. was supported in her research partially by the GoJelly project and partially by the Apulian Regional program "Research for Innovation—REFIN" (practice code number AFD9B120, project idea UNISAL119).

**Institutional Review Board Statement:** The jellyfish *Rhizostoma pulmo* is an invertebrate (Cnidaria) which is not an endangered or protected species; therefore, no permit was needed for sampling, which was conducted during jellyfish blooms. In the absence of specific guidelines for the slaughter of cnidarians [19], a method was employed that minimizes the potential for distress or pain in all animal taxa, based on the latest new taxa-specific knowledge of their physiology and anatomy.

**Informed Consent Statement:** Not applicable.

**Data Availability Statement:** All related data and methods are presented in this paper. Additional inquiries should be addressed to the corresponding author.

**Acknowledgments:** The authors thank Leone D'Amico for his valuable technical assistance in JF treatment, and Mariella Quarto and Salvatore Lisi for administrative assistance. The authors also deeply thank Mauro Bleve for the manuscript's English revision. The elemental analyses were supported by the Consorzio Interuniversitario di Ricerca in Chimica dei Metalli nei Sistemi Biologici (C.I.R.C.M.S.B.).

**Conflicts of Interest:** The authors declare no conflict of interest.
