Pathway-Based Metabolomics Reveals Biosynthetic Routes of Flavor and Pigment Compounds in Pomegranate

A joint study between theCitrus Research and Education Center of the University of Florida (Alfred, Florida) and the United States Department of Agriculture/University of California (Davis, California) developed a comprehensive metabolomics approach employing gas chromatography-mass spectrometry (GC-MS) and liquid chromatography-mass spectrometry (LC-MS) techniques to identify flavor compounds and precursors in pomegranates. Their findings offer a foundation for breeding efforts aimed at improving sensory traits in the fruit, ultimately enhancing consumer satisfaction. A paper based on their research was published in RSC Advances (1).

Although pomegranates are one of the oldest known edible fruit tree species, pomegranate production was hindered for years because the fruit is difficult to eat. This has resulted in a relatively low level or retail attractiveness (2) In the past two decades, however, the market for this fruit has experienced significant growth, stimulated by an increase in demand by consumers seeking “superfruits,” or fruits that are both high in nutrients and taste good (3).

Understanding of the formation and regulation of flavor compounds is crucial for the improvement and preservation of a food’s flavor, as steps taken to increasing yield might inadvertently affect the taste, the researchers believed that a pathway-focused metabolomics approach is important for uncovering the metabolic processes responsible for producing significant flavor elements in pomegranate. As no pathway-based metabolomics research has been conducted on California-grown pomegranate to date, the research team conducted targeted metabolomics to profile essential primary and secondary metabolites to reveal key flavor pathways, including organic acids, amino acids, sugars, hormones, and phenolic compounds. The team also analyzed pomegranate-specific compounds such as anthocyanins, punicalagins, and flavor-related volatiles (1).

In this study, four cultivars (a type of cultivated plant selected for desired traits and which retains those traits when propagated [4]) were selected to represent the diversity within U.S. pomegranate production, with “Wonderful” being the dominant cultivar and “Azadi,” “Phoenicia,” and “Eversweet” chosen to offer alternatives in acidity and peel color (5). The “Azadi” cultivar was included because of its strong reported resistance to anthracnose fruit rot disease, a trait which highlights its agricultural importance (6). The researchers employed solid phase microextraction (SPME) to extract volatile compounds, and 27 of these compounds were determined from pomegranate juice, 25 of which were fully confirmed using the authentic standards and the remaining pair tentatively identified by resonance ionization (RI) and MS (1).

The researchers report that the results demonstrated the flow of metabolites through these pathways and underscored the connections between flavor precursors and their end products. Based on their findings, they state that possible mechanisms for the formation and regulation of key flavor compounds in pomegranate were identified and discussed, and innovative insights were uncovered concerning biosynthesis processes occurring within the four cultivars analyzed. Notably, the “Wonderful” cultivar showed an increase in cellular components pertaining to metabolite pathways, which leads to an increase in the production of phenolic compounds, terpenes, fatty acids, and jasmonic acid (JA) derivatives. While this increase may enhance its antioxidant properties, it may also result in the fruit having a more bitter taste, which might reduce consumer preference. As “Wonderful” is the dominant cultivar in California, the researchers believe that further research, particularly focusing on gene expression and phylogenetic analysis, is necessary to fully understand these biosynthetic processes and their impact on flavor development (1).

References

1. An, J. P.; Kim, D.; Song, X. et al. Uncovering the Biosynthetic Pathways of Key Flavor and Color Compounds in Pomegranate Using Pathway-Based Metabolomics. RSC Adv. 2025,15 (28), 22831-22842. DOI: 10.1039/d5ra00511f

2. Asadi-Gharneh, H. A.; Mohammadzamani, M.; Karimi, S.(2017) Evaluation of Physico-Chemical Properties and Bioactive Compounds of Some Iranian Pomegranate Cultivars. Int. J. Fruit Sci. 2017, 17 (2), 175-187, DOI: 10.1080/15538362.2016.1275923

3. Hegazi, N. M.; El-Shamy, S.; Heba Fahmy, H. et al. Pomegranate Juice as a Super-Food: A Comprehensive Review of its Extraction, Analysis, and Quality Assessment Approaches. J. Food Compos. Anal. 2021, 97, 103773. DOI: 10.1016/j.jfca.2020.103773

4. Cultivar. Wikipedia. https://en.wikipedia.org/wiki/Cultivar (accessed 2025-07-08)

5. Chater, J. M.; Merhaut, D. J.; Jia, Z. et al. Fruit Quality Traits of Ten California-Grown Pomegranate Cultivars Harvested Over Three Months. Sci. Hortic. (Amsterdam) 2018, 237, 11-19. DOI: 10.1016/j.scienta.2018.03.048

6. Schaller, A.; Chater, J. M.; Vallad, G. E. et al. Pomegranate Cultivars with Diverse Origins Exhibit Strong Resistance to Anthracnose Fruit Rot Caused by Colletotrichum gloeosporioides, A Major Disease in Southeast United States. Horticulturae 2023, 9 (10), 1097. DOI: 10.3390/horticulturae9101097