3. Results and Discussion

3.1. Macronutrient Composition of Apricot Kernels

The moisture content of the apricot kernels ranged from 3.3 to 4.7 g/100 g, whereas ash content varied between 2.2 and 2.7 g/100 g (Table 2). These moisture values were comparable to or slightly lower than those reported in previous studies. For instance, apricot kernels from Malatya, Türkiye, contained 3.4% moisture and 2.5% ash [4], whereas kernels from New Zealand contained 4.7% moisture and 2.9% ash [22]. The analysed kernels contained 40.0%–49.9% fat and 17.9%–18.9% protein. These values are within the ranges reported in the literature, where protein content varies from 14.6% to 28.8% [3, 23–27] and fat content from 40.8% to 57.1 g/100 g [24, 27]. Compared with New Zealand apricot kernels, which contain 52% fat and 20.6% protein [22], the cultivars examined in the present study showed slightly lower values. Such variation is attributable to differences in genotype, growing conditions, climate and geographic origin.

Samples | Moisture (g/100 g) | Fat (g/100 g) | Protein (g/100 g) | Glucose (g/100 g) | Fructose (g/100 g) | Crude fibre (g/100 g) | Ash (g/100 g) | NFE
Suhany | 3.30 ± 0.09b | 44.00 ± 0.04b | 17.87 ± 2.46a | 0.53 ± 0.18b | 0.70 ± 0.16c | 8.80 ± 0.60c | 2.73 ± 0.06a | 22.06a
Kandek | 4.66 ± 0.15a | 48.00 ± 1.37a | 18.89 ± 0.64a | 0.68 ± 0.02b | 2.82 ± 0.37b | 8.12 ± 2.56c | 2.22 ± 0.06a | 16.65b
Kurmaiy | 3.75 ± 0.07b | 49.93 ± 0.41a | 18.70 ± 1.07a | 3.60 ± 0.07a | 3.27 ± 1.94a | 10.32 ± 2.25b | 2.69 ± 0.24a | 8.31c
Kurmaiy, sulphured | 3.33 ± 0.21b | 44.63 ± 8.69b | 17.87 ± 1.59a | 3.65 ± 0.09a | 3.32 ± 0.04a | 14.66 ± 0.92a | 2.69 ± 0.25a | 7.36с
EuroFIR [23] | 8 | 50.70 | 25.00 | 0.3 | 0.8 | 2.11 | 

Only low concentrations of glucose and fructose were detected, whereas sucrose and sorbitol were not present in the analysed kernels. Crude fibre content ranged from 8.1 to 14.7 g/100 g, exceeding most previously reported values for apricot kernels (0.8–4.3 g/100 g) [23, 24], but remaining comparable to those reported for sweet apricot kernels (12.5 g/100 g) [25] and almonds (10.2–15.2 g/100 g) [23]. It should also be noted that crude fibre values are not directly comparable with total dietary fibre because the crude fibre method quantifies mainly insoluble fibre fractions, including cellulose, lignin and pentosans, while excluding most soluble fibre components, such as inulin and pectin. Therefore, the higher crude fibre values observed in this study are unlikely to be explained by methodological differences between crude fibre and total dietary fibre determinations. Instead, the discrepancy may be due to cultivar characteristics, sample preparation procedures and analytical approaches. For example, in the study of [24], the seed coat was removed before analysis, which may have significantly reduced the measured fibre content. Overall, significant differences in macronutrient composition were observed among apricot cultivars, suggesting a strong genetic influence on kernel composition. In contrast, sulphur treatment did not appear to affect the nutritional composition of the kernels.

3.2. Amino Acid Composition of Apricot Kernels

The results of the amino acid analysis of apricot kernels are presented in Table 3. Apricot kernels contained 17 amino acids, among which glutamic acid was the most abundant, accounting for 18.5%–26% of the total amino acid content. In the present study, glutamic acid represents the combined content of glutamic acid and glutamine. This amino acid has also been reported as the predominant amino acid in almond, peach and mango kernels [28, 29]. Siberian apricot kernels, a variety of apricot, were reported to contain 29 g/100 g of protein and to be rich in glutamic acid (26.5%), aspartic acid (11.3%) and arginine (10.1%) [30]. Although glutamic acid is a nonessential amino acid, it plays a crucial role in numerous biological processes, including metabolism, neurotransmission and plant growth. Owing to its functional properties, it is also widely used in the food and agricultural industries [31].

Amino acid | Suhany | Kandek | Kurmayi
AA | Mean | SD | Mean | SD | Mean | SD
Asn + Asp | 1.34 | 0.25 | 0.98 | 0.08 | 1.14 | 0.12
Thra | 0.37 | 0.07 | 0.30 | 0.02 | 0.39 | 0.08
Ser | 0.54 | 0.10 | 0.41 | 0.03 | 0.49 | 0.09
Gln + Glu | 3.05 | 0.60 | 2.18 | 0.17 | 2.54 | 0.28
Gly | 0.65 | 0.13 | 0.49 | 0.04 | 0.60 | 0.06
Ala | 0.59 | 0.11 | 0.46 | 0.04 | 0.48 | 0.05
Cys | 0.00 | 0.00 | 0.00 | 0.00 | 0.07 | 0.00
Vala | 0.51 | 0.09 | 0.40 | 0.03 | 0.53 | 0.08
Meta | 0.00 | 0.00 | 0.00 | 0.00 | 0.12 | 0.17
Ilea | 0.45 | 0.08 | 0.34 | 0.03 | 0.37 | 0.04
Leua | 0.84 | 0.15 | 0.65 | 0.05 | 0.71 | 0.09
Tyr | 0.38 | 0.07 | 0.29 | 0.02 | 0.18 | 0.01
Phea | 0.65 | 0.12 | 0.50 | 0.03 | 0.78 | 0.15
Hisa | 0.29 | 0.06 | 0.22 | 0.02 | 0.05 | 0.07
Lysa | 0.39 | 0.08 | 0.31 | 0.03 | 0.22 | 0.02
Arg | 1.20 | 0.24 | 0.86 | 0.07 | 0.97 | 0.10
Pro | 0.55 | 0.10 | 0.41 | 0.04 | 0.58 | 0.04
Total AA | 11.8 | 2.25 | 8.8 | 0.7 | 10.22 | 1.45
SUM EAA | 3.5 | 0.65 | 2.72 | 0.21 | 3.17 | 0.7

In contrast to our findings, apricot kernels from India were reported to contain high levels of aspartic acid and tyrosine, which together accounted for more than 40% of the total amino acid content [8]. The next most abundant amino acids were arginine and leucine, with concentrations ranging from 0.97 to 1.20 mg/100 g kernels and from 0.70 to 0.88 mg/100 g of kernels, respectively. No significant differences were observed in the amino acid composition among the analysed samples.

The apricot kernels studied contained 29.7%–31.1% essential amino acids relative to total amino acid content, with leucine, phenylalanine and valine being the predominant essential amino acids. In almonds (Prunus dulcis), essential amino acids account for 36%–45% of the total amino acid content, with leucine, phenylalanine and isoleucine being the major amino acids [28]. Therefore, apricot kernels are comparable to almonds in terms of amino acid quality. Moreover, these essential amino acids play important physiological roles. Leucine and valine are branched‐chain amino acids involved in muscle protein synthesis, energy metabolism and tissue repair, whereas phenylalanine serves as a precursor to tyrosine and several neurotransmitters, including dopamine, epinephrine and norepinephrine, which support normal nervous system function [32]. The presence of these essential amino acids highlights the potential nutritional and functional value of apricot kernels as a source of dietary protein.

It should be noted that the near‐zero concentrations of methionine and cysteine observed in the present study are likely attributable to methodological limitations rather than their actual absence. Sulphur‐containing amino acids are susceptible to oxidation and degradation during acid hydrolysis, which may result in their underestimation or nondetection. More accurate quantification can be achieved by oxidising methionine and cysteine before hydrolysis and subsequently measuring their stable oxidation products after hydrolysis. However, this approach requires a modified procedure and a different separation method.

3.3. Fatty Acid Composition of the Apricot Kernel and Oil

Table 4 presents the fatty acid profiles of apricot kernels and their oil. The major fatty acids in the apricot kernel oil were oleic acid (C18:1, cis‐9), accounting for 64% of total fatty acids, followed by linoleic acid (C18:2, cis‐9,12; 19.25%) and palmitic acid (C16:0; 3.76%). Smaller amounts of stearic, linolenic and palmitoleic acids were also detected. Similar results were reported for apricot kernel oil from Poland, where oleic acid was the predominant fatty acid (60.01%–70.56%), followed by linoleic acid (19.74%–23.52%), palmitic acid (2.35%–5.97%), stearic acid (0.8%–1.5%) and palmitoleic acid (0.2%–0.9%) [33].

Fatty acids | Kandek | Kurmaiy | Suhany | Suhany, kern oil
Mean | SD | Mean | SD | Mean | SD | Mean | SD
Caproic acid (C6:0) | nd |  | 0.014a | 0.00 | nd |  | nd | 
Caprylic acid (C8:0) | 0.06 | 0.01 | 0.07 | 0.02 | 0.06 | 0.01 | 0.06 | 0.01
Myristic acid (C14:0) | nd |  | nd |  | nd |  | 0.02a | 0.00
Palmitic acid (C16:0) | 1.86b | 0.01 | 1.37c | 0.11 | 1.89b | 0.01 | 3.76a | 0.06
Palmitoleic acid (C16:1, cis‐9) | 0.30b | 0.00 | 0.21c | 0.02 | 0.34b | 0.00 | 0.56a | 0.01
Heptadecenoic (С17:1, cis‐10) | 0.04c | 0.00 | 0.03c | 0.00 | 0.05b | 0.00 | 0.11a | 0.00
Stearic acid (C18:0) | 0.40b | 0.04 | 0.37b | 0.01 | 0.48a | 0.03 | nd | 
Oleic acid (C18:1, cis‐9) | 29.83b | 0.40 | 24.60c | 2.30 | 29.06b | 0.27 | 64.37a | 0.70
Linoleic acid (C18:2, cis‐9,12) | 8.23 | 0.10 | 5.86 | 0.53 | 9.01 | 0.02 | 19.25 | 0.15
γ‐Linolenic acid (C18:3, cis‐6,9,12) | nd |  | 0.01 | 0.01 | nd |  | 0.01 | 0.01
α‐Linolenic acid (C18:3, cis‐9,12,15) | 0.03 | 0.01 | 0.03 | 0.01 | 0.03 | 0.01 | 0.09 | 0.01
Arachidic acid (C20:0) | 0.04 | 0.03 | 0.04 | 0.00 | 0.05 | 0.01 | 0.10 | 0.01
Erucic acid (22:1, cis‐13) | 0.06 | 0.01 | 0.05 | 0.01 | 0.05 | 0.01 | 0.11 | 0.00
Behenic acid (C22:0) | nd |  | nd |  | nd |  | 0.02 | 0.02
Docosadienoic acid (C22:2. c13.c16) | 0.07b | 0.02 | 0.15 | 0.05 | 0.08b | 0.01 | 0.19a | 0.05
Tricosylic acid (C23:0) | nd |  | 0.02 | 0.03 | nd |  | 0.02 | 0.02
Lignoceric acid (24:0) | 0.02 | 0.01 | 0.01 | 0.01 | 0.02 | 0.01 | 0.04 | 0.01
Docosahexaenoic acid (22:6) | 0.02d | 0.01 | 0.05a | 0.01 | 0.01 | 0.00 | 0.04b | 0.01
Sum of identified FA | 44.84 | 0.20 | 36.51 | 0.25 | 44.79 | 0.01 | 92.29 | 0.35
Unknown | 0.77 | 0.191 | 1.49 | 0.25 | 0.80 | 0.01 | 2.70 | 0.35
SFA | 2.21 |  | 1.61 |  | 2.29 |  | 4.39 | 
MUFA | 30.22 |  | 24.89 |  | 29.51 |  | 65.16 | 
PUFA | 8.330 |  | 6.07 |  | 9.12 |  | 19.53 | 
Sum of all FA | 46.40 b |  | 38.00 c |  | 45.60 b |  | 95.00 a | 

One hundred grammes of the edible portion of apricot kernels contained 24–29 g of oleic acid (C18:1, cis‐9), 5–9 g of linoleic acid (C18:2, cis‐9,12) and 1.3–1.8 g of palmitic acid (C16:0). Alajil et al. [8] reported oleic acid contents ranging from 10.73 to 29.79 g/100 g, linoleic acid contents from 4.68 to 17.69 g/100 g and palmitic acid contents from 0.31 to 1.09 g/100 g in apricot kernels. These findings suggest that the fatty acid composition of apricot kernels may be influenced by cultivar and geographical origin. Linoleic acid (C18:2, cis‐9,12) is an essential omega‐6 fatty acid that contributes to the maintenance of normal blood cholesterol levels and cardiovascular health. Oleic acid has been associated with beneficial effects on lipid metabolism, and replacing saturated fatty acids with oleic acid contributes to the maintenance of normal LDL‐cholesterol levels [32]. According to the National Research Council (United States), the adequate intake of linoleic acid is approximately 8–9 g/day (about 4% of total energy intake in a 2000 kcal diet) [34]. Based on the fatty acid composition determined in the present study, consumption of 30 g of sweet apricot kernels would provide approximately 7.2–8.7 g oleic acid. This corresponds to approximately 27%–34% of the recommended daily intake of linoleic acid and represents a substantial dietary source of oleic acid.

3.4. Mineral Composition of Apricot Kernels

Table 5 presents the macro‐ and micronutrient contents of apricot kernels. The K and Mg contents of apricot kernels were comparable to those reported for almonds, which contain approximately 835 and 170 mg/100 g, respectively [23, 32]. Among the studied cultivars, the highest K concentration was in the Suhany cultivar (812.79 mg/100 g). The average K content of the investigated samples was 564.36 mg/100 g, which is consistent with values reported in the German Food Composition Database (Version 3.2) for apricot kernels [23]. K is an essential electrolyte involved in maintaining fluid balance, supporting muscle function and regulating heart rhythm [35]. Considering that a typical serving size of nuts is approximately 30 g, apricot kernels can provide about 2.5%–7% of the recommended daily K intake (RDI) [36].

Samples | Zn | Fe | Mn | Cu | Mg | Ca | Na | K
Suhany | 3.22b | 1.90a | 0.64a | 0.84a | 156.13b | 105.09b | 0.75a | 812.79a
Kandek | 4.00a | 2.20a | 0.96a | 1.03a | 216.13a | 166.18a | 1.69a | 589.35b
Kurmaiy | 2.05b | 0.93a | 0.42a | 0.44a | 91.85c | 79.76c | 1.10a | 290.95c
Apricot kern [23] | 4.25 | 9.2 | 0.3 | 1.026 | 234 | 26 | 4 | 599

The highest Mg concentration was found in the Kandek cultivar. Mg is an essential mineral involved in numerous physiological processes, including DNA synthesis, protein synthesis, energy production, blood glucose regulation, transmembrane ion transport, oxidative phosphorylation and glycolysis, and normal muscle and nervous system function [34]. The RDI for Mg is approximately 350 mg for adults [36]. Therefore, 30 g of apricot kernels can provide 7%–20% of the daily Mg requirement.

The calcium (Ca) concentration in the investigated apricot kernels ranged from 79.8 to 166.2 mg/100 g, exceeding values reported in previous studies [23]. Ca is essential for the development and maintenance of bones and teeth, muscle contraction and vitamin D–related metabolic processes [37]. Given the RDI of 1000 mg for adults [36], a 30 g serving of apricot kernels can provide approximately 2.4%–5.0% of the daily Ca requirement.

Copper (Cu) concentrations ranged from 0.44 mg/100 g in the Kurmayi cultivar to 1.3 mg/100 g in the Kandek cultivar. Cu plays an important role in haemoglobin synthesis, iron (Fe) metabolism, energy production, enzymatic reactions and biological electron transfer processes [38]. The RDI of Cu is approximately 0.5–1 mg for children and 2 mg for adults [36]. Accordingly, a 30 g serving of apricot kernels can provide approximately 13%–78% of the daily Cu requirement, depending on cultivar and age group.

Manganese (Mn) concentrations ranged from 0.42 to 0.96 mg/100 g. Mn functions as an indirect antioxidant, contributes to bone and connective tissue formation and serves as a cofactor for enzymes involved in amino acid, carbohydrate and catecholamine metabolism. It is also required for cholesterol and nucleotide synthesis [39]. Based on the recommended daily intake of 5 mg/day for adults [36], a 30 g serving of apricot kernels can provide approximately 2.4%–5.4% of the daily Mn requirement.

Apricot kernels contained 2–4 mg zinc (Zn) per 100 g, which is consistent with values reported for apricot kernels from Turkey (1.18–4.24 mg/100 g) [40]. Zn is involved in numerous metabolic processes and acts as a structural or catalytic component of many enzymes. It is essential for the metabolism of carbohydrates, proteins, fats and nucleic acids and plays an important role in gene expression, hormone regulation and vitamin metabolism [38, 41]. With an RDI of approximately 8–11 mg/day for adults [36], 30 g of apricot kernels can provide about 8%–11% of the daily Zn requirement.

The Fe concentration was within the range previously reported in the literature (1.07–7.49 mg/100 g) [40, 42], although the German Food Composition Database reports a higher value of 9.5 mg/100 g [23]. These differences may be attributed to variations in cultivar, geographical origin, environmental conditions or analytical methodology. Among the studied cultivars, Kandek exhibited the highest Fe concentration. Fe is an essential component of haemoglobin, myoglobin and numerous enzymes involved in oxygen transport and cellular metabolism [43]. The RDI of Fe is approximately 10 mg/day for men and 18 mg/day for women [34]. Therefore, a 30 g serving of apricot kernels can provide approximately 3%–13% of the daily Fe requirement, depending on cultivar.

3.5. Bioactive Components of Apricot Kernels

Table 6 presents the total polyphenol content, ascorbic acid content and antioxidant activity of the studied apricot kernels. The TPC of the investigated samples ranged from 29 to 194.8 mg GAE/100 g dry weight (DW), which is consistent with previously reported values. Alajil et al. [8] reported TPC values ranging from 39.7 to 130.9 mg GAE/100 g DW in apricot kernels, whereas Korekar et al. [44] reported values between 92.2 and 162.1 mg GAE/100 g DW. Considerably higher concentrations of phenolic compounds have been reported in apricot kernel peels (874.5 mg GAE/100 g), exceeding those found in peels of almonds (Amygdalus pedunculata Pall.), which contained 781.8 mg GAE/100 g [45].

Samples | TPC (mg GAE/100 g DW) | Vitamin C content (mg/100 g) | Antioxidant capacity (IC50) (mg/mL)
Suhany | 29.5 ± 9.4c | 2.2 ± 1.7b | 26.5 ± 1.7c
Kandek | 38.3 ± 0.3b | 2.8 ± 0.3b | 14.7 ± 1.5b
Kurmaiy | 40.5 ± 0.5b | 2.3 ± 0.3b | 15.0 ± 0.5c
Kurmay, sulphured | 194.8 ± 1.3a | 7.1 ± 0.2a | 12.5 ± 1.7a

The antioxidant activity of the samples was evaluated using the DPPH radical‐scavenging assay and expressed as the inhibitory concentration (IC50). Previous studies reported IC50 values ranging from 43.8 to 123.4 mg/mL for apricot kernels [44]. The IC50 values obtained in the present study were generally lower, indicating stronger radical‐scavenging activity. However, the results of the in vitro DPPH assay should be interpreted with caution, as they cannot be directly extrapolated into in vivo biological effects. The DPPH assay primarily reflects the chemical ability of compounds to neutralise free radicals under controlled laboratory conditions and is therefore most suitable for preliminary screening of antioxidant potential. Confirmation of biological relevance requires further investigation using appropriate in vivo or cellular models.

The ascorbic acid content of the investigated apricot kernels ranged from 2.2 to 7.1 mg/100 g. A literature review notes that apricot kernels are rich in ascorbic acid but give no numeric vitamin C concentration for kernels. Sulphured kernels exhibited significantly higher levels of total phenolics and ascorbic acid than untreated samples. In addition, the lowest IC50 values were observed in sulphured kernels, indicating greater antioxidant activity. The enhanced antioxidant capacity may be related to higher ascorbic acid content and improved preservation of phenolic compounds during processing. Nevertheless, the comparison between sulphured and nonsulphured samples may have been influenced by other factors, including cultivar differences, processing conditions and storage history. Therefore, the observed differences cannot be attributed exclusively to SO2 treatment, which should be considered a limitation of the present study.

3.6. Amygdalin and Safety Considerations

A limitation of the present study is that amygdalin, the principal cyanogenic glycoside in apricot kernels, was not directly quantified in the analysed samples. Therefore, safety considerations related to cyanogenic potential were assessed based on published data for sweet apricot cultivars. Previous studies have demonstrated that sweet apricot kernels generally contain substantially lower amygdalin concentrations (32–235 _μ_g/g DW) than bitter genotypes (538–24,000 _μ_g/g DW), although considerable variation has been reported depending on cultivar, geographical origin and analytical methodology [46]. Similar concentrations, ranging from trace levels to approximately 235 _μ_g/g DW, have also been reported for commercially available sweet apricots [46]. Assuming a conservative worst‐case scenario based on the highest reported concentration (235 _μ_g/g DW), consumption of a 30 g serving of apricot kernels would provide approximately 7.05 mg of amygdalin. Given that 1 g of amygdalin can theoretically release approximately 59 mg of HCN, this amount would correspond to a potential exposure of approximately 0.416 mg HCN. For a 70‐kg adult, this equates to about 5.94 _μ_g HCN/kg body weight, which is below the acute reference dose for cyanide established by the European Food Safety Authority (EFSA) of 20 _μ_g/kg body weight [47]. It should be emphasised that this estimate represents a deliberately conservative upper‐bound scenario and is likely to overestimate actual exposure for most sweet cultivars, which typically contain lower amygdalin concentrations. Nevertheless, considering the substantial natural variability of cyanogenic glycoside content among apricot kernels, direct quantification of amygdalin should be included in future studies to enable a more accurate assessment of consumer safety. Until such data become available, moderate consumption is advisable, particularly for children and other potentially sensitive population groups.