The study addresses a persistent blind spot in pepper science. Most previous metabolomic investigations have focused on fresh or freeze-dried fruits, leaving the biochemistry of hot air-dried peppers, the form most commonly consumed as spice powder in Korea and much of Asia, poorly characterized. Because drying concentrates and transforms metabolites, the chemical identity of a pepper powder cannot simply be inferred from fresh-fruit studies. The research team, led by scientists from Chung-Ang University and Seoul National University, harvested both cultivars at the Yeongyang Pepper Research Institute of the Rural Development Administration in August and September 2021, then dried the fruits using a standardized hot air protocol before separating the three fruit tissues for analysis.

The analytical strategy combined three complementary platforms. Gas chromatography coupled to triple quadrupole mass spectrometry quantified primary metabolites including amino acids, sugars, and fatty acids using multiple reaction monitoring. High-performance liquid chromatography with diode array detection measured carotenoids, while an integrated workflow of ultra-high-performance liquid chromatography with Orbitrap high-resolution mass spectrometry and triple quadrupole mass spectrometry annotated and quantified phenolic compounds. Capsaicinoids were determined by HPLC with ultraviolet detection. In total, the team identified 160 primary metabolites, of which 75 matched previously reported Capsicum metabolites and 85 were newly detected or structurally uncharacterized, alongside capsaicinoids, carotenoids, and 39 phenolic compounds.

Principal component analysis of the resulting data revealed a striking degree of structure. The first two components explained 89.7 percent of total variance, with the first component accounting for 58.9 percent and separating samples primarily by cultivar, and the second component accounting for 30.8 percent and separating them by tissue type. Hierarchical clustering confirmed this pattern, showing that cultivar and tissue identity, rather than harvest timing, were the dominant drivers of overall metabolic variation. This finding carries practical weight: it suggests that breeders and processors can reliably target specific cultivar-tissue combinations to obtain desired chemical profiles, while harvest date exerts a more selective influence on particular quality markers.

The amino acid results were among the most nutritionally significant. The placenta of Subicho, the landrace, contained markedly elevated levels of essential amino acids, including threonine, methionine, tryptophan, histidine, lysine, and leucine, across all tissues analyzed. The researchers interpret this as evidence of a higher capacity for protein biosynthesis in the Subicho reproductive tissue, consistent with the placenta’s role as a metabolically active organ. Subicho also accumulated substantial 4-hydroxyproline, a building block of hydroxyproline-rich glycoproteins in plant cell walls. Bulcolor, by contrast, showed higher levels of glutamic acid, the amino acid responsible for umami flavor, hinting at a sensory advantage in flavor-oriented applications.

Sugar profiles reinforced the cultivar divide. Subicho consistently contained higher concentrations of the reducing sugars glucose and fructose in placenta and pericarp tissues, roughly 1.5 to 1.7 times the levels found in Bulcolor, while Bulcolor’s pericarp held 3.7 times more sucrose than Subicho. These differences provide a physiological basis for the sensory variation between powders made from the two cultivars and could guide breeding strategies aimed at optimizing sweetness and flavor in dried pepper products.

Fatty acid and vitamin data told a story about breeding history. Bulcolor tissues accumulated higher levels of linoleic acid and alpha-linolenic acid, both essential fatty acids in the human diet and known precursors of lipid-derived plant signaling compounds. Previous work has linked fatty acid desaturase and lipoxygenase genes in Capsicum annuum to responses against tobamoviruses, and the elevated polyunsaturated fatty acid content of Bulcolor appears consistent with its development as a cultivar resistant to the resistance-breaking tomato spotted wilt virus isolate TSWV-WJ. Bulcolor was also enriched in alpha- and delta-tocopherol, antioxidants that protect against oxidative stress, and in the sterols stigmasterol and sitosterol, which contribute to membrane stability and environmental stress resistance. Subicho’s placenta, meanwhile, contained higher levels of nucleobases such as thymine, cytosine, adenine, and guanine, aligning with its amino acid abundance.

Capsaicinoid measurements delivered some of the study’s most dramatic numbers. Total capsaicinoid content ranged from 42.5 to 89.9 micrograms per gram in pericarp, 8,148.1 to 16,879.5 micrograms per gram in placenta, and just 17.3 to 85.7 micrograms per gram in seed. The placenta, which constitutes less than 4 percent of total dry weight, thus holds the overwhelming majority of a pepper’s pungency, confirming earlier estimates that it accounts for roughly 96 percent of total capsaicinoids. The single highest value, 16,879.5 micrograms per gram, was recorded in the Subicho placenta at the first harvest. In both cultivars, capsaicin concentrations fell substantially by the second harvest; Subicho placental capsaicin dropped from 9,444.7 to 5,091.8 micrograms per gram. The authors attribute this decline to metabolic changes during ripening, possibly including peroxidase-mediated degradation of capsaicinoids after maturation.

Carotenoid analysis showed a complementary tissue specialization. Six carotenoids were identified, with capsanthin, the pigment responsible for red pepper coloration and a compound associated with antioxidant and antitumor activity, consistently predominant at 155.1 to 179.9 micrograms per gram. Beta-carotene dominated the placenta at 67.3 to 97.3 micrograms per gram, while alpha-carotene appeared only in the pericarp, and no carotenoids were detected in seeds. Multivariate analysis flagged capsanthin and beta-carotene as biomarker metabolites distinguishing tissues and cultivars, and total carotenoid content was consistently higher in the pericarp than the placenta, with Bulcolor exceeding Subicho. Phenolic profiling added further resolution: chlorogenic acid was enriched in Bulcolor pericarp and placenta, vanillic acid was abundant in the Subicho placenta and in the seeds of both cultivars, and 4-hydroxybenzoic acid concentrated in seeds, where it may contribute antimicrobial and antioxidant capacity.

The practical implications extend across breeding, industry, and consumer choice. The cultivar-, tissue-, and harvest-specific database established here provides a scientific reference for selecting cultivars optimized for particular purposes, whether enhanced nutrition, pungency, color, or flavor, and for directing specific pepper tissues toward targeted uses in food processing. It also supports rigorous quality assessment of pepper powders, a product category whose commercial value depends heavily on consistent chemical composition. While the authors note that cultivar and harvest coverage in the study was limited, the framework demonstrates how comprehensive metabolomics can transform an everyday spice into a precisely engineered ingredient, giving producers evidence-based tools and consumers a clearer understanding of what determines the heat, color, and nutritional character of the red pepper on their table.

Subject of Research: Comparative metabolomic profiling of tissue-specific Korean red pepper powders from the Subicho and Bulcolor cultivars

Article Title: Comparative metabolomic profiling of tissue-specific Korean red pepper (Capsicum annuum L.) powders from Subicho and Bulcolor cultivars

Article References: Yu, H., Park, E., Lee, J.-H., Kim, S., Ku, K.-H., Choi, J. H., Chun, H. S., Lim, J.-H., & Lee, J. (2026). Comparative metabolomic profiling of tissue-specific Korean red pepper (Capsicum annuum L.) powders from Subicho and Bulcolor cultivars. Food Science and Biotechnology. https://doi.org/10.1007/s10068-026-02274-x

Image Credits: AI Generated

DOI: 10.1007/s10068-026-02274-x

Keywords: metabolomics, Capsicum annuum, Korean red pepper, capsaicinoids, carotenoids, polyphenols, Subicho, Bulcolor, placenta, pericarp, harvest timing, food science