{"status":"ok","message-type":"work","message-version":"1.0.0","message":{"indexed":{"date-parts":[[2026,6,19]],"date-time":"2026-06-19T22:50:24Z","timestamp":1781909424541,"version":"3.54.5"},"reference-count":49,"publisher":"MDPI AG","issue":"8","license":[{"start":{"date-parts":[[2022,4,14]],"date-time":"2022-04-14T00:00:00Z","timestamp":1649894400000},"content-version":"vor","delay-in-days":0,"URL":"https:\/\/creativecommons.org\/licenses\/by\/4.0\/"}],"funder":[{"name":"Texas Woman's University - Chancellor Research Fellow","award":["NA"],"award-info":[{"award-number":["NA"]}]},{"name":"National Watermelon Promotion Board","award":["No. 00704263"],"award-info":[{"award-number":["No. 00704263"]}]}],"content-domain":{"domain":[],"crossmark-restriction":false},"short-container-title":["Molecules"],"abstract":"<jats:p>Watermelon rind is treated as agricultural waste, causing biomass loss and environmental issues. This study aimed to identify free amino acids and volatiles in watermelon rind, flesh, and rind-flesh juice blends with ratios of 10%, 20%, and 30%. Among the 16 free amino acids quantified, watermelon rind alone contained higher total amino acids (165 mg\/100 g fresh weight) compared to flesh alone (146 mg\/100 g). The rind had significantly higher (1.5\u00d7) and dominant amounts of citrulline and arginine (61.4 and 53.8 mg\/100 g, respectively) than flesh. The rind, however, contained significantly lower amounts of essential amino acids. Volatile analysis showed that watermelon rind total volatiles (peak area) comprised only 15% of the flesh volatiles. Of the 126 volatiles identified, the rind alone contained 77 compounds; 56 of these presented in all five samples. Aldehydes and alcohols were most prevalent, accounting for &gt;80% of the total volatiles in all samples. Nine-carbon aldehyde and alcohol compounds dominated both the flesh and rind, though the rind lacked the diversity of other aldehydes, alcohols, ketones, terpenes, terpenoids, esters and lactones that were more abundant in the watermelon flesh. Watermelon rind was characterized by the major aroma compounds above their thresholds, including 17 aldehydes and six unsaturated nine-carbon alcohols. This study demonstrated the potential for rind as a food or beverage supplement due to its key features such as concentrated citrulline and arginine, relatively low odor intensity, and valuable volatiles associated with fresh, green, cucumber-like aromas.<\/jats:p>","DOI":"10.3390\/molecules27082536","type":"journal-article","created":{"date-parts":[[2022,4,19]],"date-time":"2022-04-19T01:03:01Z","timestamp":1650330181000},"page":"2536","update-policy":"https:\/\/doi.org\/10.3390\/mdpi_crossmark_policy","source":"Crossref","is-referenced-by-count":23,"title":["Free Amino Acids and Volatile Aroma Compounds in Watermelon Rind, Flesh, and Three Rind-Flesh Juices"],"prefix":"10.3390","volume":"27","author":[{"ORCID":"https:\/\/orcid.org\/0000-0003-1596-5684","authenticated-orcid":false,"given":"Xiaofen","family":"Du","sequence":"first","affiliation":[{"name":"Department of Nutrition and Food Sciences, Texas Woman\u2019s University, Denton, TX 76204, USA"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"ORCID":"https:\/\/orcid.org\/0000-0002-2095-2477","authenticated-orcid":false,"given":"Mindy","family":"Davila","sequence":"additional","affiliation":[{"name":"Department of Nutrition and Food Sciences, Texas Woman\u2019s University, Denton, TX 76204, USA"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Jessica","family":"Ramirez","sequence":"additional","affiliation":[{"name":"Department of Nutrition and Food Sciences, Texas Woman\u2019s University, Denton, TX 76204, USA"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Cierra","family":"Williams","sequence":"additional","affiliation":[{"name":"Department of Nutrition and Food Sciences, Texas Woman\u2019s University, Denton, TX 76204, USA"}],"role":[{"vocabulary":"crossref","role":"author"}]}],"member":"1968","published-online":{"date-parts":[[2022,4,14]]},"reference":[{"key":"ref_1","doi-asserted-by":"crossref","first-page":"e109102","DOI":"10.1016\/j.scienta.2019.109102","article-title":"Expression pattern of sugars and organic acids regulatory genes during watermelon fruit development","volume":"265","author":"Gao","year":"2020","journal-title":"Sci. Hortic."},{"key":"ref_2","doi-asserted-by":"crossref","first-page":"e109086","DOI":"10.1016\/j.foodres.2020.109086","article-title":"Recovery of high value-added compounds from pineapple, melon, watermelon and pumpkin processing by-products: An overview","volume":"132","author":"Rico","year":"2020","journal-title":"Food Res. Int."},{"key":"ref_3","doi-asserted-by":"crossref","first-page":"2545","DOI":"10.1007\/s13762-021-03310-5","article-title":"Valorisation of watermelon (Citrullus lanatus) rind waste into bioethanol: An optimization and kinetic studies","volume":"19","author":"Kassim","year":"2022","journal-title":"Int. J. Environ. Sci. Technol."},{"key":"ref_4","doi-asserted-by":"crossref","first-page":"426","DOI":"10.1039\/c2ee23440h","article-title":"Food waste as a valuable resource for the production of chemicals, materials and fuels. current situation and global perspective","volume":"6","author":"Lin","year":"2013","journal-title":"Energy Environ. Sci."},{"key":"ref_5","doi-asserted-by":"crossref","first-page":"1699","DOI":"10.1007\/s12010-011-9521-7","article-title":"Watermelon rind: Agro-waste or superior biosorbent?","volume":"167","author":"Liu","year":"2012","journal-title":"Appl. Biochem. Biotechnol."},{"key":"ref_6","doi-asserted-by":"crossref","first-page":"e122626","DOI":"10.1016\/j.jclepro.2020.122626","article-title":"Development of watermelon rind derived activated carbon\/manganese ferrite nanocomposite for cleaner desalination by capacitive deionization","volume":"272","author":"Rambabu","year":"2020","journal-title":"J. Clean. Prod."},{"key":"ref_7","doi-asserted-by":"crossref","unstructured":"M\u00e9ndez, D.A., Fabra, M.J., G\u00f3mez-Mascaraque, L., L\u00f3pez-Rubio, A., and Martinez-Abad, A. (2021). Modelling the extraction of pectin towards the valorisation of watermelon rind waste. Foods, 10.","DOI":"10.3390\/foods10040738"},{"key":"ref_8","doi-asserted-by":"crossref","first-page":"57","DOI":"10.1016\/j.foodhyd.2016.10.040","article-title":"Pectins from food waste: Extraction, characterization and properties of watermelon rind pectin","volume":"65","author":"Petkowicz","year":"2017","journal-title":"Food Hydrocoll."},{"key":"ref_9","doi-asserted-by":"crossref","first-page":"805","DOI":"10.1002\/jsfa.4250","article-title":"Bioactive compounds from flesh and by-product of fresh-cut watermelon cultivars","volume":"91","author":"Viegas","year":"2011","journal-title":"J. Sci. Food Agric."},{"key":"ref_10","doi-asserted-by":"crossref","first-page":"196","DOI":"10.1016\/j.chroma.2005.05.009","article-title":"Determination of citrulline in watermelon rind","volume":"1078","author":"Rimando","year":"2005","journal-title":"J. Chromatogr. A"},{"key":"ref_11","doi-asserted-by":"crossref","first-page":"230","DOI":"10.3923\/ajb.2015.230.236","article-title":"Comparative assessment of some mineral, amino acid and vitamin compositions of watermelon (Citrullus lanatus) rind and seed","volume":"10","author":"Egbuonu","year":"2015","journal-title":"Asian J. Biochem."},{"key":"ref_12","doi-asserted-by":"crossref","first-page":"415","DOI":"10.1111\/j.1745-4549.2003.tb00863.x","article-title":"Chemical, physical and sensory characterization of watermelon rind pickles","volume":"26","author":"Simonne","year":"2003","journal-title":"J. Food Process. Preserv."},{"key":"ref_13","first-page":"1545","article-title":"Effective jam preparations from watermelon waste","volume":"19","author":"Souad","year":"2012","journal-title":"Int. Food Res. J."},{"key":"ref_14","doi-asserted-by":"crossref","first-page":"83","DOI":"10.1016\/j.aoas.2013.01.012","article-title":"Utilization of watermelon rinds and sharlyn melon peels as a natural source of dietary fiber and antioxidants in cake","volume":"58","author":"Ahmed","year":"2013","journal-title":"Ann. Agric. Sci."},{"key":"ref_15","first-page":"14","article-title":"Drying of watermelon rind and development of cakes from rind powder","volume":"2","author":"Hoque","year":"2015","journal-title":"Int. J. Nov. Res. Life Sci."},{"key":"ref_16","doi-asserted-by":"crossref","first-page":"415","DOI":"10.1007\/s10068-016-0057-z","article-title":"Utilization of watermelon rind waste as a potential source of dietary fiber to improve health promoting properties and reduce glycemic index for cookie making","volume":"25","author":"Naknaen","year":"2016","journal-title":"Food Sci. Biotechnol."},{"key":"ref_17","first-page":"59","article-title":"Effect of watermelon (Citrullus lanatus) rind flour supplementation on the quality of wheat based cookies","volume":"6","author":"Olaitan","year":"2017","journal-title":"Int. J. Eng. Sci."},{"key":"ref_18","doi-asserted-by":"crossref","first-page":"223","DOI":"10.1007\/s42853-020-00061-y","article-title":"Assessment of the potential of watermelon rind powder for the value addition of noodles","volume":"45","author":"Chakrabarty","year":"2020","journal-title":"J. Biosyst. Eng."},{"key":"ref_19","first-page":"465","article-title":"Effect of watermelon rind powder on physicochemical, textural, and sensory properties of wet yellow noodles","volume":"14","author":"Ho","year":"2016","journal-title":"CyTA\u2014J. Food"},{"key":"ref_20","doi-asserted-by":"crossref","first-page":"177","DOI":"10.21608\/jfds.2018.35852","article-title":"Effect of addition watermelon rind powder on quality criteria and microbial aspects of beef burger patties during frozen storage periods","volume":"9","author":"Badr","year":"2018","journal-title":"J. Food Dairy Sci."},{"key":"ref_21","doi-asserted-by":"crossref","first-page":"e13757","DOI":"10.1111\/jfpp.13757","article-title":"Antioxidant and antimicrobial efficacy of watermelon rind extract (WMRE) in aerobically packaged pork patties stored under refrigeration temperature (4 \u00b1 1 \u00b0C)","volume":"42","author":"Kumar","year":"2018","journal-title":"J. Food Process. Preserv."},{"key":"ref_22","doi-asserted-by":"crossref","first-page":"e105802","DOI":"10.1016\/j.mimet.2019.105802","article-title":"Eco-friendly, economic fungal universal medium from watermelon peel waste","volume":"168","author":"Hasanin","year":"2020","journal-title":"J. Microbiol. Methods"},{"key":"ref_23","doi-asserted-by":"crossref","first-page":"806","DOI":"10.3923\/pjn.2010.806.809","article-title":"Improvement of the biochemical properties of watermelon rinds subjectted to saccharomyces cerevisae solid media fermentation","volume":"9","author":"Erukainure","year":"2010","journal-title":"Pak. J. Nutr."},{"key":"ref_24","doi-asserted-by":"crossref","first-page":"e127306","DOI":"10.1016\/j.jclepro.2021.127306","article-title":"Using watermelon rind and nitrite-containing wastewater for electricity production in a membraneless biocathode microbial fuel cell","volume":"307","author":"Yang","year":"2021","journal-title":"J. Clean. Prod."},{"key":"ref_25","doi-asserted-by":"crossref","first-page":"208","DOI":"10.1016\/j.tifs.2021.03.002","article-title":"Citrullus lanatus as source of bioactive components: An up-to-date review","volume":"111","author":"Zamuz","year":"2021","journal-title":"Trends Food Sci. Technol."},{"key":"ref_26","doi-asserted-by":"crossref","first-page":"393","DOI":"10.1016\/j.scienta.2018.01.032","article-title":"Watermelon and melon fruit quality: The genotypic and agro-environmental factors implicated","volume":"234","author":"Kyriacou","year":"2018","journal-title":"Sci. Hortic."},{"key":"ref_27","doi-asserted-by":"crossref","first-page":"1384","DOI":"10.1111\/1750-3841.15648","article-title":"Consumer acceptance of watermelon flesh-rind blends and the effect of rind on refreshing perception","volume":"86","author":"Ramirez","year":"2021","journal-title":"J. Food Sci."},{"key":"ref_28","doi-asserted-by":"crossref","first-page":"e00769","DOI":"10.3389\/fpls.2019.00769","article-title":"Inside and beyond color: Comparative overview of functional quality of tomato and watermelon fruits","volume":"10","author":"Ilahy","year":"2019","journal-title":"Front. Plant Sci."},{"key":"ref_29","doi-asserted-by":"crossref","unstructured":"Du, X., and Ramirez, J. (2022). Watermelon rind and flesh volatile profiles and cultivar difference. Horticulturae, 8.","DOI":"10.3390\/horticulturae8020099"},{"key":"ref_30","doi-asserted-by":"crossref","first-page":"1542","DOI":"10.1111\/1750-3841.14165","article-title":"Analysis and evaluation of the characteristic taste components in portobello mushroom","volume":"83","author":"Wang","year":"2018","journal-title":"J. Food Sci."},{"key":"ref_31","doi-asserted-by":"crossref","first-page":"30","DOI":"10.1007\/s10681-019-2356-y","article-title":"QTLs associated with flesh quality traits in an elite \u00d7 elite watermelon population","volume":"215","author":"Fall","year":"2019","journal-title":"Euphytica"},{"key":"ref_32","doi-asserted-by":"crossref","first-page":"307","DOI":"10.1016\/j.jfca.2010.06.005","article-title":"Bioactive compounds and antioxidant activities of different watermelon (Citrullus lanatus (thunb.) mansfeld) cultivars as affected by fruit sampling area","volume":"24","author":"Tlili","year":"2011","journal-title":"J. Food Compos. Anal."},{"key":"ref_33","doi-asserted-by":"crossref","unstructured":"Gao, L., Zhao, S., Lu, X., He, N., Zhu, H., Dou, J., and Liu, W. (2018). Comparative transcriptome analysis reveals key genes potentially related to soluble sugar and organic acid accumulation in watermelon. PLoS ONE, 13.","DOI":"10.1371\/journal.pone.0190096"},{"key":"ref_34","doi-asserted-by":"crossref","first-page":"689","DOI":"10.1016\/j.foodchem.2015.06.011","article-title":"Quantification of prominent volatile compounds responsible for muskmelon and watermelon aroma by purge and trap extraction followed by gas chromatography-mass spectrometry determination","volume":"190","author":"Fredes","year":"2016","journal-title":"Food Chem."},{"key":"ref_35","doi-asserted-by":"crossref","first-page":"119","DOI":"10.1016\/j.foodres.2018.02.022","article-title":"Comparison of fresh watermelon juice aroma characteristics of five varieties based on gas chromatography-olfactometry-mass spectrometry","volume":"107","author":"Liu","year":"2018","journal-title":"Food Res. Int."},{"key":"ref_36","doi-asserted-by":"crossref","first-page":"1677","DOI":"10.1007\/s12161-018-1153-x","article-title":"Comparison of SPME versus SAFE processes for the analysis of flavor compounds in watermelon juice","volume":"11","author":"Liu","year":"2018","journal-title":"Food Anal. Methods"},{"key":"ref_37","doi-asserted-by":"crossref","first-page":"323","DOI":"10.1080\/10412905.2014.933449","article-title":"Volatile constituents of mini-watermelon fruits","volume":"26","author":"Dima","year":"2014","journal-title":"J. Essent. Oil Res."},{"key":"ref_38","doi-asserted-by":"crossref","first-page":"448","DOI":"10.1080\/14620316.2014.11513105","article-title":"Volatile organic compounds in watermelon (citrullus lanatus) grafted onto 21 local and two commercial bottle gourd (Lagenaria siceraria) rootstocks","volume":"89","author":"Guler","year":"2014","journal-title":"J. Hortic. Sci. Biotechnol."},{"key":"ref_39","first-page":"24","article-title":"Identification of aroma compounds in watermelon juice by SPMEGCMS","volume":"944","author":"Tang","year":"2012","journal-title":"Int. Soc. Hortic. Sci."},{"key":"ref_40","doi-asserted-by":"crossref","first-page":"7789","DOI":"10.1021\/jf060663l","article-title":"Characterization and semiquantitative analysis of volatiles in seedless watermelon varieties using solid-phase microextraction","volume":"54","author":"Beaulieu","year":"2006","journal-title":"J. Agric. Food Chem."},{"key":"ref_41","doi-asserted-by":"crossref","first-page":"193","DOI":"10.1111\/j.1365-2621.1990.tb06050.x","article-title":"Evaluation of potent odorants in cucumbers (Cucumis sativus) and muskmelons (Cucumis melo) by aroma extract dilution analysis","volume":"55","author":"Schieberle","year":"1990","journal-title":"J. Food Sci."},{"key":"ref_42","doi-asserted-by":"crossref","first-page":"e110478","DOI":"10.1016\/j.lwt.2020.110478","article-title":"Screening of the volatile compounds in fresh and thermally treated watermelon juice via headspace-gas chromatography-ion mobility spectrometry and comprehensive two-dimensional gas chromatography-olfactory-mass spectrometry analysis","volume":"137","author":"Yang","year":"2021","journal-title":"LWT"},{"key":"ref_43","doi-asserted-by":"crossref","first-page":"137","DOI":"10.1016\/j.postharvbio.2019.03.018","article-title":"Linking consumer sensory acceptability to volatile composition for improved shelf-life: A case study of fresh-cut watermelon (Citrullus lanatus)","volume":"154","author":"Stanley","year":"2019","journal-title":"Postharvest Biol. Technol."},{"key":"ref_44","doi-asserted-by":"crossref","first-page":"945","DOI":"10.1002\/jsfa.10023","article-title":"Evolution of volatile compounds in \u2018Cuoredolce\u00ae\u2019 and \u2018Rugby\u2019 mini- watermelons (Citrullus lanatus (thunb.) matsumura and nakai) in relation to ripening at harvest","volume":"100","author":"Bianchi","year":"2020","journal-title":"J. Sci. Food Agric."},{"key":"ref_45","doi-asserted-by":"crossref","unstructured":"Yang, X., Yang, F., Liu, Y., Li, J., and Song, H.-L. (2020). Identification of key off-flavor compounds in thermally treated watermelon juice via gas chromatography\u2013olfactometry\u2013mass spectrometry, aroma recombination, and omission experiments. Foods, 9.","DOI":"10.3390\/foods9020227"},{"key":"ref_46","first-page":"3145","article-title":"Volatile flavor components of watermelon (Citrullus vulgaris)","volume":"49","author":"Yajima","year":"1985","journal-title":"Agric. Biol. Chem."},{"key":"ref_47","doi-asserted-by":"crossref","first-page":"e109681","DOI":"10.1016\/j.foodres.2020.109681","article-title":"Investigating sensory properties of seven watermelon varieties and factors impacting refreshing perception using quantitative descriptive analysis","volume":"138","author":"Ramirez","year":"2020","journal-title":"Food Res. Int."},{"key":"ref_48","doi-asserted-by":"crossref","first-page":"3142","DOI":"10.1021\/jf047927t","article-title":"Carotenoid pigmentation affects the volatile composition of tomato and watermelon fruits, as revealed by comparative genetic analyses","volume":"53","author":"Lewinsohn","year":"2005","journal-title":"J. Agric. Food Chem."},{"key":"ref_49","doi-asserted-by":"crossref","first-page":"1410","DOI":"10.1021\/acsfoodscitech.1c00229","article-title":"Egg white partially substituted with mushroom: Taste impartment with mushroom amino acids, 5\u2032-nucleotides, soluble sugars, and organic acids, and impact factors","volume":"1","author":"Du","year":"2021","journal-title":"ACS Food Sci. Technol."}],"container-title":["Molecules"],"original-title":[],"language":"en","link":[{"URL":"https:\/\/www.mdpi.com\/1420-3049\/27\/8\/2536\/pdf","content-type":"unspecified","content-version":"vor","intended-application":"similarity-checking"}],"deposited":{"date-parts":[[2025,10,10]],"date-time":"2025-10-10T22:54:13Z","timestamp":1760136853000},"score":1,"resource":{"primary":{"URL":"https:\/\/www.mdpi.com\/1420-3049\/27\/8\/2536"}},"subtitle":[],"short-title":[],"issued":{"date-parts":[[2022,4,14]]},"references-count":49,"journal-issue":{"issue":"8","published-online":{"date-parts":[[2022,4]]}},"alternative-id":["molecules27082536"],"URL":"https:\/\/doi.org\/10.3390\/molecules27082536","relation":{},"ISSN":["1420-3049"],"issn-type":[{"value":"1420-3049","type":"electronic"}],"subject":[],"published":{"date-parts":[[2022,4,14]]}}}