Research in Plant Metabolites

Research in Plant Metabolites

Diversity of Color Parameters and Anthocyanin Content in the Petals of Pomegranate (Punica granatum L.) Genotypes of Khuzestan, Iran

Articles in Press

Document Type : Original Article

Authors
Fatemeh Mohsen Nasab 1
Mokhtar Heidari 2
Mansoore Shamili 3
1 Department of Horticultural Sciences, University of Hormozgan, Bandar Abbas, Iran,
2 Associate Professor, Department of Horticultural Science, Agricultural Sciences and Natural Resources University of Khuzestan, Mollasani, Iran
3 Department of Horticultural Sciences, University of Hormozgan, Bandar Abbas, Iran
10.22034/jrpsm.2026.580102.1111
Abstract
Background and Objectives: Pomegranate (Punica granatum L.) is valued for its high nutritional and bioactive compounds, including phenolics, flavonoids, and anthocyanins. While most studies have focused on the fruit, peel, and arils, little is known about the biochemical composition of pomegranate petals. In traditional medicine, pomegranate flowers are used to treat conditions such as diabetes, inflammation, and aphthous stomatitis. Anthocyanins, as key natural pigments, not only attract pollinators but also represent a healthy alternative to synthetic colorants in the food and pharmaceutical industries. Given the high genetic diversity of pomegranates in the Baghmalek region of Khuzestan and the lack of data on petal composition, this study aimed to evaluate color indices and anthocyanin content in the petals of 24 pomegranate genotypes. The findings may support the use of petals as a natural color source and inform breeding programs for improved visual and nutritional quality.
Materials and Methods: This study was conducted on 24 pomegranate genotypes in the Baghmalek region, Khuzestan Province. Flower samples were collected at full bloom stage from the second week of April to the first week of May 2023. Healthy hermaphrodite flowers were harvested from four directions of marked trees and immediately transferred to the laboratory. After drying at ambient temperature, total anthocyanins were extracted using acidified ethanol (HCl:ethanol, 15:85), and absorbance was measured at 535 nm. Color indices—including color intensity (CI), pure red color index (dA), hue, total color density (TCD), and the proportions of yellow, red, and blue colors—were calculated based on absorbance at 420, 520, and 620 nm. Data were analyzed using Excel, Minitab 16, and SAS 9.4. Mean comparisons were performed using Duncan’s test at a 0.05 probability level. To classify genotypes based on color traits, hierarchical cluster analysis using Ward’s method was applied via Past software (v4.03).
Results: Significant differences were observed among genotypes in color indices and anthocyanin content. The highest yellow index (18.94 AU₄₂₀) was recorded in genotype 24, while the highest red index (16.8 AU₅₂₀) was found in genotypes 14 (‘Sabz Shirin Alafi’) and 18 (‘Qermez Daneh Robi’). Total anthocyanin content (based on cyanidin-3-glucoside) was also highest in genotypes 24 (‘Dane Siah Robi -Alafi’) and 14 (‘Sabz Shirin Alafi’) (17.92 and 16.77 mg/L, respectively). Cluster analysis divided the genotypes into three distinct groups: Group I with moderate color and balanced yellow/red pigments, Group II with light color and dominant yellow/orange pigments, and Group III with dark color and high red/purple pigment and anthocyanin content. Genotypes 14 (‘Sabz Shirin Alafi’), 18 (‘Qermez Daneh Robi’), and 24 (‘Dane Siah Robi -Alafi’) fell into Group III and were identified as superior in terms of natural color potential and nutritional value. An inverse relationship was observed between absorbance at 520 nm and absorbances at 420 and 620 nm, suggesting the conversion of monomeric to polymeric anthocyanins and enhanced color stability.
Conclusion: This study revealed considerable diversity in color indices and anthocyanin content among pomegranate petals from the Baghmalek region. Genotypes with dark-colored petals and high anthocyanin levels—particularly 14, 18, and 24 (‘Sabz Shirin Alafi’, ‘Qermez Daneh Robi’ and ‘Dane Siah Robi -Alafi’)—show strong potential as natural colorant sources for food and pharmaceutical applications. These genotypes may also be valuable in breeding programs aimed at enhancing visual and nutritional quality. Further studies are recommended to identify specific anthocyanin types in petals and to correlate color indices with other biochemical parameters.
Keywords
Pomegranate
Flower
Phenolics
Flavonoids
Quality
Natural colorant
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