Composition Comparison of Selected Stone Fruits: Peach, Nectarine and Apricot

2.1 Study period, harvest maturity, and sampling regions

The research was conducted during the growing seasons of 2021-2024. Fruits were harvested at botanical ripeness, which for the studied varieties occurred from the third decade of June to the first decade of September, depending on varietal ripening time. The maturity standard was based on typical varietal size, colour, and external ripeness characteristics, and fruits with visible mechanical damage, disease symptoms, or atypical appearance were excluded. Laboratory analyses were performed immediately after receipt of fresh samples, from July to October in each study year. The sampling locations were the Tutrakan, Silistra, and Varna districts of north-eastern Bulgaria, which represent important areas of industrial stone-fruit cultivation in the country. The orchards belonged to conventional production systems. The regions differed in microclimatic conditions: Varna is influenced by the Black Sea, while Tutrakan and Silistra have more continental inland conditions. Exact tree age and detailed cultivation-management variables were not used as controlled experimental factors; therefore, the results are interpreted as applying to the studied varieties, batches, and production conditions.

2.2 Plant material and laboratories

The determination of dry matter, carbohydrate profile, total titratable acidity, tannins, and vitamin C was performed by the author in the laboratory of commodity science of the University of Varna, Bulgaria. The content of provitamin A, expressed as β-carotene, was determined in the accredited laboratory “Alimenti-Omnilab” of “D&V CONSULT” Ltd., Tsaratsovo, Plovdiv region, Bulgaria. The object of the study was stone fruit at botanical ripeness, obtained from conventional production in the Tutrakan, Silistra, and Varna districts, with varietal identification ensured at sampling. The following peach varieties were studied: “Royal Glory”, “Redhaven”, “Glohaven”, and “O’Henry”; nectarine varieties: “Sungrand”, “Goldengrand”, “Fantasia”, and “Morsiani 90”; and apricot varieties: “Ungarska”, “Delmast”, “Roksana”, and “Silistrenska Kompotna”.

2.3 Experimental design, sampling, and sample preparation

For each of the 12 varieties, three independent fruit batches were formed as biological replicates. Each batch was collected by random sampling from five trees of the same variety within one farm and contained at least 5 kg of fruit. From each batch, 30 fruits typical in size and colour were selected for laboratory analysis. Before analysis, fruits were visually inspected, washed, drained, separated from stones where required, and the edible part was homogenised to obtain a representative analytical sample. Each indicator was determined three times for each batch; therefore, the design included three biological replicates and three technical determinations per replicate, giving nine determinations per variety for each measured indicator.

2.4 Analytical methods

The analytical workflow included sample preparation, determination of water content and dry matter, determination of carbohydrate fractions, titratable acidity, tannins, vitamin C, and β-carotene, followed by calculation of descriptive statistics and comparison between varieties and species. Water content was determined by azeotropic distillation using xylene as the organic solvent, in accordance with ISO 1026:1982 [11]. Dry matter was calculated as the complementary non-aqueous fraction of the fruit sample and expressed as a percentage. The carbohydrate block included reducing sugars, total sugars, and sucrose. Sugars were determined by a chemical redox method with quantitative determination of residual copper after oxidation, in accordance with BDS 7169:1989 [12]. Sucrose was calculated within the carbohydrate profile, and the sugar-acid ratio was interpreted using total sugars and total titratable acidity as the main comparative indicators.

2.5 Determination of titratable acidity and tannins

Total titratable acidity was determined in an aqueous extract of the homogenised fruit sample by titration with 0.1 N sodium hydroxide solution to the phenolphthalein end point, in accordance with ISO 750:1998 [13] and BDS 6996:1993 [14]. The indicator was expressed as a percentage and used to compare the acid block within and between fruit groups. Tannins were determined by the Leventhal method in a cold medium using potassium permanganate in an acidic environment and indigo carmine as an indicator. Because potassium permanganate oxidises tannins and other oxidisable compounds, a differential approach was applied: the total extract was titrated, then tannins were adsorbed on activated carbon, and the extract was titrated again. Tannin content was calculated from the difference between the two titrations and expressed as a percentage.

2.6 Determination of vitamin C and β-carotene

Vitamin C was determined titrimetrically using 2,6-dichlorophenolindophenol as a redox indicator, according to BDS 11812:1991 [15], and expressed as mg/100 g. β-carotene was determined by high-performance liquid chromatography after extraction of carotenoids from the fruit matrix and saponification of the extract to remove lipid impurities. During saponification, the temperature was kept below 80 ℃ to reduce the risk of isomerisation and oxidation of β-carotene, and the procedure followed the operational requirements of BS EN 12823-1:2014 [16]. β-carotene values were expressed as mg/kg and used as a provitamin A marker for comparison between varieties and fruit groups.

2.7 Data handling and descriptive statistics

For each variety, three independent fruit batches were used as biological replicates (n = 3). For each biological replicate, each indicator was measured three times as technical replicates. The three technical determinations were averaged to obtain one value per biological replicate. The final values were then expressed as the arithmetic mean ± standard deviation for the three biological replicates. Descriptive statistics included mean, standard deviation, standard error of the mean, minimum, and maximum values. Normality was checked using the Shapiro-Wilk test, and homogeneity of variance was assessed using Levene’s test.

2.8 Inferential statistics

When the assumptions of normality and homogeneity of variance were met, one-way analysis of variance (ANOVA) was used to test differences between varieties within each species. Differences were considered statistically significant at p < 0.05. When ANOVA indicated significant differences, Tukey’s HSD test was applied for pairwise comparison. When the assumptions for parametric testing were not met, the Kruskal-Wallis test was used. For interspecific comparison of generalised indicators, an independent two-sample t-test was used for normally distributed data, while the Mann-Whitney U test was used for non-normal distributions. Statistical processing was carried out using Statistica 12.0 and Microsoft Excel 2016.

The compositional profiles of peaches, nectarines, and apricots were differentiated by several interconnected groups of indicators: dry matter, carbohydrate fractions, total titratable acidity, tannins, vitamin C, and β-carotene. These differences should be interpreted not as evidence of the overall superiority of one fruit or variety, but as differences in compositional orientation under the conditions of this study. Dry matter reflects the concentration of the non-aqueous fraction and is important for processing yield and texture; sugars and acidity jointly shape taste and sugar-acid balance; tannins are related to the phenolic block; and vitamin C and β-carotene reflect nutritional markers with different stability during storage and processing [17-21]. Therefore, the same numerical direction does not have the same meaning for all uses: higher sugar content may be favourable for sweet taste or some processing purposes, higher acidity may be useful for products requiring pronounced acid balance, and higher β-carotene or vitamin C may indicate nutritional advantages without necessarily meaning better overall fruit quality.

The observed differences may be linked to varietal genotype, maturity stage, microclimatic conditions, and cultivation background. Since the samples were obtained from conventional production in north-eastern Bulgaria and the exact tree age and detailed cultivation management were not controlled as separate experimental factors, the results should be considered primarily applicable to the studied varieties, batches, years, and growing conditions. This interpretation is consistent with studies showing that stone-fruit composition is influenced by genotype, ripening stage, environmental conditions, and post-harvest or processing factors.

The accumulation of organic acids in peach in combination with metabolomic and transcriptomic characteristics was considered by Song et al. [22], where the acid profile of fruits was analysed in connection with the functioning of metabolic pathways that regulate the synthesis, transformation, and deposition of organic acids during fruit formation. The work showed that variations in acidity were accompanied by changes in the content of basic organic acids, as well as differences in the expression of genes associated with vacuolar transport, enzymatic reactions of the tricarboxylic acid cycle, and the redistribution of metabolites in fruit tissues. The acidity of peach fruits in the studied genotypes remained at a level below 1%, while differences were recorded between individual varieties both in terms of the general acid background and in the ratio of individual acids. This approach allowed considering acidity not only as an analytical indicator, but as the result of a combination of genotypic features with environmental regulation of metabolism. Within the framework of the conducted study, the organic acid block in peach was also characterised by variability within the species, and the varietal distribution of acidity indicators formed one of the axes of intraspecific differentiation. Comparison with the data of Song et al. [22] shows that variations in acidity in peach can be interpreted as a manifestation not only of quantitative differences between varieties, but also of different intensities of metabolic processes associated with the accumulation of organic acids.

Gómez-Martínez et al. [23] showed that for apricots, the carbohydrate profile was formed mainly by sucrose and glucose, while in the acid block, the leading place was occupied by malic and citric acids. Within the framework of this work, differences were observed between cultivars both in the total content of sugars and in the concentrations of individual organic acids, which reflected different types of intraspecific organisation of the chemical composition. Along with this, the analysis of ascorbic acid revealed intervarietal variation, which complemented the differentiation of apricot by carbohydrate and acid components. Thus, the authors’ results characterized apricot as a crop within which the sugar, acid, and vitamin blocks do not change in isolation, but within a common varietal configuration. This relationship is consistent with the results of the study, where for all three groups of stone fruits in the carbohydrate profile, the dominance of sucrose was recorded, and apricot was distinguished by a different position in the acid block. The varietal differentiation in vitamin C established for apricot also correlates with the data of Gómez-Martínez et al. [23], in which ascorbic acid varied between cultivars along with fluctuations in the sugar and acid profile. Taken together, this allows considering apricot as a separate compositional model within stone fruits, where the dominance of sucrose is combined with a more pronounced contribution of organic acids and with differentiation of the vitamin component.

The phenolic profile of apricot as a sign of genotypic differentiation was characterised by Morales et al. [24], where the content of individual groups of phenolic compounds was used to distinguish varieties and genotypes within the harvesting season. In this work, the analysis covered not only the total content of phenolic substances, but also the distribution of individual phenolic classes, which made it possible to trace which components formed intervarietal differences. It was shown that the phenolic profile of apricot changed depending on the genotype, and the ratio between individual phenolic compounds served as the basis for chemical differentiation of the studied material. With this approach, the phenolic block appeared not as a homogeneous indicator, but as a multicomponent system, within which varietal differentiation occurred through the quantitative ratios of individual substances. In the study, the phenolic component was represented by the content of tannins and the intraspecific ranking of varieties according to this indicator. Comparison with the results of Morales et al. shows that the integral representation of the phenolic block through tannins is consistent with the general logic of varietal differentiation, while the detailing to the level of individual phenolic classes reveals the internal structure of this variability at a deeper analytical level.

Meena et al. [25] summarised data on the chemical composition of stone fruits, focusing on carbohydrates, organic acids, vitamins, carotenoids, and phenolic compounds as the main components that determine the nutritional and biochemical characteristics of the fruits. Within the framework of the review analysis, it was shown that the variability of the composition of stone fruits is formed under the influence of genotype, growing conditions, degree of ripeness, post-harvest processes, and technological processing. Such a description scheme allows considering the composition of fruits as a system of interconnected blocks, where not only the absolute content of individual substances is important, but also the ratio between individual components. The results of the comparison of peaches, nectarines, and apricots correlate with this approach, since all three groups presented a common set of basic blocks: dry matter, sugars, organic acids, tannins, vitamin C, and β-carotene. The differences were manifested not in the set of components, but in the limits of the variations and in the nature of the combination of individual blocks within each species. In particular, the concentration component in peaches and nectarines formed a wider range of varietal fluctuations, while apricots were characterised by a different position of the acid block in the overall structure of the composition. Thus, the generalisation of Meena et al. [25] correlates with the data obtained at the level of a systematic description of the sources of variability of stone fruits.

Comparative analysis of composition and antioxidant characteristics at the level of cultivars of another fruit object was applied by Yasmin et al. [26], where intervarietal differences were traced by the set of nutrient and bioactive components, and the chemical profile of each cultivar was described as a combination of several interrelated indicators. Within the framework of this work, it was shown that varietal differentiation was not reduced to one dominant parameter, but was formed through a combination of sugars, organic acids, antioxidant components, and accompanying biochemical characteristics. This approach correlates with the results of the study of stone fruits, where each group also had its own configuration of the leading axes of variation. For peaches and nectarines, the central place in the differentiation system was occupied by dry matter and the carbohydrate block, while for apricots, the acid component and β-carotene were more clearly manifested. In this ratio, varietal variability was revealed as a structural distribution of indicators within the species, and interspecific differences were revealed as a different configuration of the same blocks within the comparative scheme. Therefore, the results of Yasmin et al. correlate with the logic of the analysis, where the compositional profile of each fruit group was described through a set of interconnected components, and not through a separate, isolated indicator.

Karaçelik [27] characterised apricot cultivars by phytochemical profiling and related bioactivity indicators, where the phenolic block was one of the parameters of intercultivar differentiation. Within the framework of this study, the analysis covered the composition of individual phytocomponents, the quantitative ratios, and the relationship with indicators of biological activity, which allowed considering the chemical profile of apricot as a multicomponent system. Intercultivar differences were traced through the unequal distribution of phenolic compounds, as well as through variations in indicators related to the antioxidant properties of fruits. This approach set a profile model of the phenolic block, within which the varietal differentiation was based on the structure of individual phytochemical components. In the study, the phenolic component of apricot was represented through the content of tannins, and the varietal ranking was based on this indicator. Comparison with the results of Karaçelik shows that the integral representation of the phenolic block through tannins is consistent with the general scheme of intervarietal differentiation, while the profiling of individual phytochemicals details the internal structure of this differentiation.

Núñez-Cárdenas et al. [28] analysed the carbon footprint of stone fruit production and showed that the final estimated values varied depending on the chosen life cycle approach and the boundaries of the assessment system. For nectarines from southeastern Spain, different quantitative indicators were obtained under alternative calculation schemes, reflecting the sensitivity of the environmental assessment to the methodology for accounting for production stages, logistics, packaging, and associated resource costs. In this context, the characteristics of the raw material can be considered as one of the background parameters accompanying the production scenarios. For peaches, nectarines, and apricots, the compositional profiles formed by dry matter, sugar-acid ratio, phenolic, and vitamin blocks set different parameters of the raw material organisation of the fruit [29-33]. With this approach, compositional indicators can be included in a broader model of describing fruit batches in processing, transportation, and storage systems, where the biochemical configuration of the raw material is correlated with the technological and logistical conditions of the agri-food chain.

The “variety-compositional profile-applied properties” approach was used by Perveen and Bokahri [34] when analysing the chemical and mineral composition of different date varieties with an additional definition of biological activity. Within the framework of this work, each variety was described through a combination of proximate indicators, mineral composition, and accompanying bioactive characteristics, which made it possible to trace how varietal affiliation correlates with a certain configuration of the nutrient profile. With this approach, the varietal level of analysis was combined with a characteristic of the potential applied properties of the fruits, which arose from the peculiarities of the composition. A similar logic was observed in the study of peaches, nectarines, and apricots, where varietal variability was manifested through the configuration of dry matter, sugars, acids, tannins, vitamin C, and β-carotene. At the same time, the comparative scheme was deployed simultaneously at two levels-intraspecific and interspecific, which allowed correlating the varietal structure of each group with the position of the species in the general space of stone fruits. Under such conditions, the compositional profile served as a form of description not only of varietal specificity but also of interspecific differentiation within related crops.

Sharma et al. [35] compared the proximate, mineral, and phytochemical composition of pomegranate separately for the peel, seeds, and powder of the whole fruit, where the key element of the analytical design was the differentiation of morphological parts of one fruit object. Within this approach, each matrix was characterised by its own combination of nutrient, mineral, and phytochemical indicators, which allowed tracing the intra-fruit heterogeneity of the composition. The distribution of components between the peel, seeds, and whole powder formed several profiles within one species, and the differences between these profiles were determined by the structure of the studied tissue and the method of sample preparation. In the study of stone fruits, the compositional profile was analysed at the level of the edible part without division into separate morphological fractions. Such a comparison fixes the difference between two schemes for describing fruit composition: matrix, focused on intra-fruit differentiation, and integral, within which the comparison is made between varieties and species according to a set of integral indicators.

The influence of different technologies for drying stone fruits on the physical, chemical, and biological properties of dry products was systematised by Vakula et al. [36]. Within the framework of the generalisation, it was shown that the final profile of dried raw materials changes depending on the temperature regime, the duration of the process, the type of drying, and the intensity of moisture removal. The changes covered both the concentration characteristics associated with dehydration and the redistribution of acids, sugars, phenolic compounds, and other components sensitive to thermal and technological action. In this context, the results for fresh peaches, nectarines, and apricots can be correlated with the initial state of the raw materials before technological transformation. Dry matter and the ratio of “sugars-acids” with this approach appear as initial parameters, relative to which the change in composition during drying can be traced. Therefore, the compositional profiles of fresh fruits form an analytical basis for further comparison with the profiles of dried products.

The mechanisms of stone formation in fruits of the genus Prunus with an emphasis on the regulation of endocarp lignification and the significance of these processes for breeding directions were described by Khan et al. [37]. In this work, attention was focused on fruit morphogenesis, tissue specialisation, and molecular biological mechanisms that determine the formation of a lignified layer around the seed. This approach characterised intrageneric variability at the level of structural organisation of the fruit and genetically controlled morphological traits. The study analysed the chemical composition of the edible part of the fruit and its varietal variability. Comparison with the work of Khan et al. shows that genotypic differentiation within Prunus manifests itself simultaneously at the morphogenetic and compositional levels: in one case, through the formation of the stone, in the second, through the ratio of dry matter, sugars, acids, phenolic components, and vitamin markers. Under such conditions, the morphological specialisation of the fruit and the biochemical configuration of the pulp can be considered as different planes of manifestation of species and varietal variability.

A comparative approach to assessing the polyphenol profile and nutritional value of non-traditional fruit species, focusing on interspecific and intersample differentiation in the content of bioactive compounds, was applied by Jurikova et al. [38]. Within the framework of this study, the phenolic block was considered as a multicomponent system in which the quantitative ratio of individual polyphenol classes formed the chemical specificity of each species. Along with phenolic components, nutritional value indicators were analysed, which allowed correlating the profile of bioactive substances with the overall composition of the fruit. This approach reflected the phenolic block as one of the central levels of interspecific differentiation. In the study of stone fruits, the phenolic component was represented through tannins as an integral indicator and through the intraspecific ranking of varieties. Comparison with the results of Jurikova et al. shows that the phenolic block can be described both in the form of a total indicator and through a detailed profile of individual polyphenolic groups, while the structure of intervarietal and interspecific differences is preserved in both analytical formats.

The influence of macronutrients on the growth, yield and quality parameters of stone fruits, linking mineral nutrition with the formation of morphological and physicochemical characteristics of fruits, was summarised by Lateef et al. [39]. Within the framework of this review, it was shown that the provision of nutrients affects the accumulation of dry matter, sugars, organic acids and accompanying components, as well as the intensity of the formation of productive and quality traits. With this approach, the compositional profile of fruits was considered as the result of the interaction of the genotype with the nutrition regime and growing conditions. In the conducted study, the main differentiation was recorded at the varietal level in terms of dry matter, acidity, and vitamin markers. Comparison with the work of Lateef et al. embeds these results in a broader agrobiological context, in which the varietal variability of composition indicators correlates with the action of soil and nutrient factors that accompany the formation of stone fruit quality.

Physicochemical analysis of apricot with the characteristics of the soil profile of the mid-mountain region, which allowed considering fruit quality indicators in connection with the conditions of the growing location, was combined by Thakur [40]. Within the framework of the study, sugars, organic acids, vitamin components and other physicochemical parameters of apricots were analysed in combination with a description of the soil properties that accompanied the cultivation of the crop. Such a scheme reflected the relationship between the composition of the fruit and the environmental characteristics of the growing location. The data of the study conducted on apricot, in particular on the acid block, sugar profile and vitamin markers, correlate with this approach in terms of considering physicochemical indicators through a combination of varietal structure and environmental conditions. Within the framework of the comparative scheme for apricots, the main place was occupied by intraspecific ranking of varieties according to the set of indicators that formed a separate configuration of the compositional profile within the species.

Cho et al. [41] performed cyanide profiling in stone fruit syrups using Prunus mume as an example using a comparison of distillation techniques and analytical derivatisation. In this study, the subject of analysis was processed products and specific safety indicators related to the content of cyanogenic compounds. This approach was focused on analytical control of components that are important for assessing the safety of finished products, as well as on comparing methodological schemes for the quantitative determination. In the study conducted for peaches, nectarines and apricots, the composition of fresh fruits was assessed in terms of dry matter, sugars, acidity, tannins, and vitamin markers. Comparison with the work of Cho et al. [41] distinguishes two planes of stone fruit characterisation: compositional, focused on the nutrient and biochemical profile, and safety, focused on the control of specific compounds in processed products.

The influence of different mulching materials on the microclimate and quality of apricot fruits, tracing changes in physicochemical indicators in connection with the modification of environmental conditions, was studied by Li et al. [42]. Within the framework of this work, parameters related to the temperature and moisture regime of the soil were analysed, as well as changes in fruit quality indicators that accompanied the use of different types of mulch. This research scheme combined agrotechnical influence with the physicochemical characteristics of apricot. In the comparison conducted, data on apricot, including the acid block and vitamin markers, correlate with the approach to considering fruit quality as a result of a combination of varietal and environmental factors. Within the framework of the comparison performed for apricots, the intraspecific configuration of indicators according to the ratio of “sugars-acid” and the vitamin block was traced.

Abdisa et al. [43] compared the proximate composition, phytochemical and antinutrient components in the pulp and seeds of another fruit object, clearly delimiting individual fruit matrices as sources of different composition profiles. Within this approach, the composition of the pulp and seeds was considered as a system of two distinct chemical spaces, each of which was characterised by its own ratios of nutrient, phytochemical and antinutrient indicators. This scheme made it possible to trace the intra-fruit heterogeneity of the composition and matrix differentiation of components. In the study of stone fruits, the compositional profile of the edible part was analysed without dividing it into pulp and seeds. Comparison with the work of Abdisa et al. [43] fixes the difference between the matrix approach, focused on the internal structure of one fruit object, and the holistic approach, within which the comparison is made between varieties and species according to the set of integral indicators.

Sample preparation methods for the quantitative determination of heavy metals in plum orchard systems, focusing on the analytical chemistry of contaminants and the methodological reproducibility of measurements, were compared by Rusu et al. [44]. Within the framework of this study, the key task was to compare laboratory procedures capable of providing a stable and comparable determination of the content of metals in plant material and related objects of the orchard system. This approach represented the sanitary-analytical direction of studying fruit raw materials. In the study conducted for peaches, nectarines and apricots, contaminants were not determined, and the quality profile was formed on the basis of dry matter, sugars, organic acids, tannins, vitamin C, and β-carotene. Comparison with the work of Rusu et al. [44] outlines the coexistence of two analytical levels in the characterisation of fruits: compositional and sanitary-chemical.

Redondo et al. [45] showed that the bulk of phenolic compounds of stone fruits are localised in the skin and pits, while in the pulp the concentration is lower and decreases during the ripening process. In this work, the spatial distribution of phenolic components in the fruit was considered as a result of tissue specialisation and ripening dynamics, which determines the differences between morphological fractions in terms of saturation with bioactive compounds. Such data correlate with the low concentrations of tannins recorded in the pulp of the studied peaches, nectarines, and apricots. With this comparison, the integral phenolic index obtained for the edible part of the fruit is consistent with the idea of an uneven distribution of phenolic compounds between the pulp, skin, and pit.

Martín-Diana et al. [46] found that varietal differences characteristic of fresh fruits were also reproduced in processed products, and some varieties retained elevated values of the phenolic profile also in by-products. In this work, the varietal specificity of the chemical composition was considered as one that preserves structural continuity when moving from fresh raw materials to processed products and secondary fractions. This approach allowed correlating the biochemical characteristics of fresh fruits with the parameters of products obtained in the technological cycle. In the study, varietal rankings for peaches, nectarines, and apricots were also formed through a combination of concentration, acid, phenolic, and vitamin blocks. Comparison with the results of Martín-Diana et al. [46] shows that the varietal structure of the compositional profile can retain analytical value for both fresh fruits and processed products.

From an applied point of view, the results are useful for separating fresh-consumption quality, processing suitability, and nutritional markers. For fresh consumption, the sugar-acid ratio is important because it affects taste balance [47-51]. For processing, dry matter can influence yield, concentration behaviour, and suitability for purées, jams, dried products, and concentrates. Acidity is relevant for recipe correction and product stability, while vitamin C and β-carotene are useful markers when selecting raw materials for products with nutritional positioning [52-56]. Therefore, varietal selection should be based on the intended use of the fruit rather than on a single indicator.

The generalisation of the comparisons showed that the established patterns corresponded to how the sources of variability in the composition of stone fruits were described in the literature, in particular, the leading role of genotypic differences in combination with the influence of environmental conditions, agrotechnical factors, and post-harvest processes. Within the framework of the comparison, interspecific differentiation was most clearly traced in the acid block, while the carbohydrate profile of all three groups was characterised by the dominance of sucrose and the preservation of the structure of basic sugars. The concentration component, represented by dry matter, acted as a background parameter that set the limits of variation for other blocks and reflected the peculiarities of the accumulation of the non-aqueous fraction within the varietal spectrum. At the same time, a comparison with works that used approaches to detailed phenolic profiling or carotenoid analysis in the post-harvest period outlined the possibility of deepening the interpretation by expanding the phenolic block from an integral indicator to the level of phenolic classes. Similarly, studies focused on the dynamics of pigment and vitamin composition during storage and processing have demonstrated the feasibility of testing the stability of vitamin markers under different growing, storage, and processing regimes. Under such conditions, the compositional profiles established for peaches, nectarines, and apricots can be considered as a basic comparative framework within which additional analytical levels of detail refine the structure of varietal rankings without changing the general system of blocks “dry matter-sugars-acids-phenolic component-vitamin markers”.