Decoding the Flavor Chemistry of Salted Plums Through GC-IMS

A joint study conducted by Zhongkai University of Agriculture and Engineering and Guangdong Academy of Agricultural Sciences, both in Guangzhou, China, investigated flavor evolution in four plum varieties using gas chromatography-ion mobility spectrometry (GC-IMS). Their research will assist in the identification of plum varieties appropriate for salt-curing as well as provide a foundation for flavor research and processing improvement of the fruit. A paper based on their study was published in Food Chemistry: X (1).

GC-IMS has been applied widely in the analysis of volatile organic compounds (VOCs) due to high sensitivity, high accuracy, low detection limit and the absence of sample pre-treatment requirements. Additionally, the technique offers a simple operation process and maximizes the retention of the original flavor of the samples (2). GC-IMS provide a fast, efficient and convenient analytical tool for fruit and vegetable processing, as well as important technical support for quality control and flavor optimization (1).

The plum (Prunus salicina L.) has a rich history of cultivation, with China being the largest producer, particularly the southern region (3). Along with the southwestern region, a particularly diverse range of plum varieties has been cultivated due to variations in ecological conditions (4). The fruit is rich in sugar, organic acids, and amino acids; the latter is known for promoting the secretion of gastric acid and digestive enzymes, enhancing gastrointestinal motility, as well as serving as an effective intestinal regulator (5). Plums also contain high levels of vitamin C, polyphenols, flavonoids, and other active substances, which aid in the enhancing of immunity and the prevention of cardiovascular and cerebrovascular diseases (6). Plum’s abundant dietary fiber also assists in lowering blood sugar levels (7).

For this study, the researchers concentrated on four specific varieties of plum: the Bingtang (BT, possessing a thin skin and thick flesh), the Pingguo (PG, exhibiting a crisp and firm flesh) the Tuogu (TG, possessing a small pit and thick flesh), and the Qilin (QL, exhibiting a sweet and crisp flesh) (1). The analysis yielded a total of 57 VOCs being identified in both fresh and salted plums, including 14 aldehydes, 3 alkenes, 7 alcohols, 16 esters, and 6 other substances. While the salting process did not generate new compounds, it did alter the composition of volatile compounds through metabolic rearrangement significantly. The proportion of aldehydes decreased, while the proportions of esters, alkenes, and alcohols increased. Fresh TG exhibited dominant grassy and fruity flavors from heptanal and hexanal, while BT, QL, and PG showed stronger apple notes from 3-methylbutyraldehyde. Salting reduced aldehydes but increased esters, alkenes, and alcohols, with eight VOCs showing significant changes. Notably, salted (S)-TG preserved original aromas, whereas S-PG underwent flavor remodeling (1)

Relative odor activity value (ROAV) analysis showed that the content of key flavor compounds in the salted plums increased by 3–5 compared to the fresh fruits, and the contribution of original core compounds (including heptanal and hexanal) was enhanced, which resulted in a complex flavor with pear, apple, lemon, and cherry notes. Based on the variance importance of projection scores from partial least squares-discriminant analysis models, 17 aroma substances were identified as potential markers. In addition, the salting process achieved a transition from a fresh grassy aroma to a salted complex fruity aroma (1).

References

1. Zhang, S.; Zhou, H.; Wang, F. et al. Salt-Induced Flavor Metamorphosis in Plums: A GC-IMS Comparative Study Unraveling Cultivar-Dependent Aroma Evolution. Food Chem. X 2025, 19 (31), 103053. DOI: 10.1016/j.fochx.2025.103053
2. Acero, N.; Gradillas, A.; Beltran, M. et al. Comparison of Phenolic Compounds Profile and Antioxidant Properties of Different Sweet Cherry (Prunus avium L.) Varieties. Food Chem.2019, 279, 260-271. DOI: 10.1016/j.foodchem.2018.12.008
3. Li, Y. B.; Wu, L.; Weng, M. J. et al. Effect of Different Encapsulating Agent Combinations on Physicochemical Properties and Stability of Microcapsules Loaded with Phenolics of Plum (Prunus salicina lindl.) Powder Tech. 2018, 340, 459-464. DOI: 10.1016/j.powtec.2018.09.049
4. Jiang, C. C.; Lin, Y. J.; Wang, X. A. Analysis and Evaluation of Fruit Nutritional Quality of Eight Southern Plum Varieties. Southern Chinese Fruit Trees2023, 52 (03), 102-108. DOI: 10.13938/j.issn.1007-1431.20220417
5. González-Flores, D.; Belén, V.; Garrido, M. et al. Ingestion of Japanese Plums (Prunus salicina Lindl. cv. Crimson Globe) Increases the Urinary 6-sulfatoxymelatonin and Total Antioxidant Capacity Levels in Young, Middle-Aged and Elderly Humans: Nutritional and Functional Characterization of Their Content. JFNR 2011,50 (4), 229-236. DOI: 10.3168/jds.2011-94-1-537
6. Dhalaria, R.; Verma, R.; Kumar, D. et al. Bioactive Compounds of Edible Fruits with their Anti-Aging Properties: A Comprehensive Review to Prolong Human Life. Antioxidants2020, 9 (11), 1123. DOI: 10.3390/antiox9111123
7. Yin, J. X.; Wu, M. F.; Lin, R. M. et al. Application and Development Trends of Gas Chromatography–Ion Mobility Spectrometry for Traditional Chinese Medicine, Clinical, Food and Environmental Analysis. Microchem. J.2021, 168, 106527. DOI: 10.1016/j.microc.2021.106527