Document Type : Research Article
Authors
1
M.Sc. Graduate, Department of Horticultural Sciences, Faculty of Agriculture, University of Zanjan, Zanjan, Iran
2
Professor, Department of Horticultural Science, Faculty of Agriculture, University of Zanjan, Zanjan, Iran
3
PhD Graduate, Department of Horticultural Science, Faculty of Agriculture, University of Zanjan, Zanjan, Iran
10.22067/jhs.2026.97655.1494
Abstract
Introduction
Almond (Prunus dulcis (Mill.) D.A. Webb) is one of the most important economic nut crops of the Rosaceae family and is widely cultivated in temperate regions worldwide due to its high adaptability and extensive genetic diversity. The species is believed to have originated in the arid and mountainous areas extending from Central Asia to the Middle East and is currently grown in major producing countries such as Iran, the United States, Turkey, China, and Pakistan. The broad genetic diversity present in almond germplasm plays a key role in adaptation to diverse environmental conditions and in tolerance to biotic and abiotic stresses. Self-incompatibility in most almond cultivars, together with frequent seed propagation, has contributed to considerable genetic differentiation within this species. The biochemical characteristics of almond kernels, including lipid, protein, mineral content, vitamin E, phenolic compounds, flavonoids, and antioxidant activity, are of great importance for nutritional value and industrial applications. These traits strongly influence kernel quality and determine the suitability of cultivars for specific uses in the food and confectionery industries. Previous studies have demonstrated substantial variation among almond genotypes in terms of biochemical composition, highlighting their potential value for breeding programs. Therefore, the present study was conducted to evaluate and compare the biochemical characteristics of seven native almond genotypes from the Khodabandeh region of Zanjan Province, Iran. The evaluated traits included mineral composition, protein and oil content, total phenolics, flavonoids, vitamin E, and antioxidant activity, with the aim of identifying superior genotypes with high nutritional quality and breeding potential. The findings of this research provide valuable information for the conservation and efficient utilization of native almond genetic resources and may contribute to the improvement of almond quality and the development of cultivars adapted to regional climatic conditions.
Methods and Materials
The present study was conducted in almond orchards located around Khodabandeh County, Zanjan Province, Iran (48°35′ E, 36°07′ N; 2050 m a.s.l.). The experiment was arranged as a complete randomized block design for seven native almond genotypes with three replications. The studied genotypes consisted of Aghbolagh 1, 2, 3, and 4, and Validaghi 1, 2, and 3, which are well adapted to the local climatic conditions and environmental stresses. Fruits were harvested at commercial maturity when hull splitting exceeded 70% and kernels were fully developed, and samples were transferred to the Postharvest Physiology Laboratory of the University of Zanjan. Biochemical analyses included antioxidant activity, total phenolics, flavonoids, vitamin E, dry matter, ash, crude protein, crude fiber, crude fat, and mineral elements (N, P, K, Fe, Mn, Zn, and Cu). Mineral elements were determined using flame photometry, spectrophotometry, atomic absorption spectrometry, and colorimetric methods. Vitamin E was quantified by HPLC, while phenolic compounds and antioxidant activity were measured using Folin–Ciocalteu and DPPH assays, respectively. Data were statistically analyzed using SAS software, and mean comparisons were performed by Duncan’s multiple range test at the 5% probability level.
Results and Discussion
Significant differences were observed among the seven almond genotypes with respect to antioxidant capacity, total phenolic content, flavonoids, vitamin E, nutritional compounds, and mineral composition, indicating substantial biochemical diversity. Antioxidant capacity ranged from 34.13% to 37.29%, with the highest value recorded in Aghbolagh 1 and 4 and the lowest in Aghbolagh 4 and 3. Total phenolic content varied markedly among genotypes, reaching a maximum values in Validaghi 3, 2 and Aghbolagh1 and a minimum value in Validaghi 1. The highest flavonoid content was observed in Aghbolagh 4 (7.0 mg 100 g⁻¹), while Aghbolagh 1 showed the lowest value. Vitamin E content ranged from 24.1 to 27.8 mg 100 g⁻¹, with Aghbolagh 2 exhibiting the highest concentration. These results confirm the important role of phenolic compounds, flavonoids, and vitamin E in determining antioxidant activity in almond kernels and are consistent with previous reports. Crude fat content ranged from 47% to 53%, with Aghbolagh 1, 2, 4 and Validaghi1 showing the highest value, making it particularly suitable for fat-based processing industries. The highest level of crude protein content recorded in Validaghi 2 and 3, highlighting its superior nutritional value. Crude fiber content ranged from 10% to 12% and was within the range reported in earlier studies. These variations reflect genetic differences among the genotypes and their potential applications in food and nutrition. Ash content, an indicator of mineral richness, was highest in Validaghi 3, 1, 2 and Aghbolagh 4 and lowest in Aghbolagh 2. Dry matter content ranged from 91.33% to 93.66%, confirming the naturally low moisture content of almond kernels and their suitability for storage. Mineral analysis revealed considerable variation among genotypes. Aghbolagh 1 exhibited the highest levels of phosphorus, potassium, zinc, and copper, while Validaghi 2 showed the highest nitrogen and iron contents. These findings demonstrate that almond kernels are a rich source of essential macro- and micronutrients. Principal component analysis (PCA) indicated that three components explained most of the variability, with the first two components accounting for 61.52% of the total variance. The first component was strongly associated with total phenolics, ash, fiber, protein, nitrogen, phosphorus, and iron, while the second component showed high loadings for most biochemical traits. Genotypes were grouped into four distinct clusters, confirming notable biochemical and genetic diversity. Overall, the results highlight the potential of certain native almond genotypes as valuable genetic resources for breeding programs aimed at improving nutritional quality and antioxidant properties.
Conclusion
This study revealed substantial variability among native almond genotypes from the Khodabandeh region of Zanjan Province regarding biochemical composition and antioxidant activity. Almond kernels were identified as rich sources of phytochemicals and nutrients beneficial for human health. Significant differences were observed among genotypes in fiber, protein, fat, ash, mineral content, vitamin E, phenolic compounds, and antioxidant activity. Genotype Validaghi 3 exhibited high dietary fiber, protein, and ash, highlighting its nutritional value. Aghbolagh 1 was rich in macro- and trace minerals, while Aghbolagh 2 showed high fat content suitable for industrial applications. Overall, the high phenolic content, antioxidant activity, and genetic diversity suggest strong potential of these genotypes for breeding programs, functional foods, and food industry applications.
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