In association with a desirable balance of sugars and organic acids, volatile compounds contribute to the important sensory attributes of apricots. This study assessed the biochemical, aromatic, and sensory qualities of ten Moroccan apricot clones at two maturity stages (M1: commercial stage and M2: consumption stage). Sucrose (1.84–7.09 g/100 g of fresh weight (FW)) and citric acid (0.56–2.25 g/100 g FW) were the main sugar and organic acid in fresh apricots, respectively. The principal identified volatile compounds classes were aldehydes, alcohols, and acetates. The major apricot volatile compounds, hexanal (15.43–696.35
Apricot was considered in the Mediterranean’s countries as one of the most delicious temperate fruits, characterized by strong fruity aroma and a good taste based on high soluble sugars and reasonable organic acids that are considered as major determinants of the quality of the fruits [
In the case of fleshy fruit such as apricot fruit, alongside agronomic aspects (regularity of yields, vigor of trees, resistance or tolerance to diseases, size, and color of fruit), internal fruit quality and appreciation of consumers are criteria taken into account earlier in the selection process. Therefore, the establishment of sensory profiles by panelists is a powerful tool for characterization of the different genotypes of apricot [
Previous studies have reported that sugars and organic acids contents play an important role in fruit taste through the sugar/acid ratio [
Consumers’ interest focuses on the flavor and aroma of apricot. The soluble sugars and organic acids were the most appreciable quality attributes of apricot [
Despite a large number of studies on the characterization of apricot quality, in particular on sugar and organic acid contents [
To the best of our knowledge, this study is the first which provides data about the biochemical and aromatic compounds composition and sensory profile of Moroccan apricots during fruit ripening. The objectives of this work were as follows: (1) to describe the fruits sensory traits of ten Moroccan apricot clones and to determine their volatile compounds; (2) to analyse some quality criteria, namely, soluble sugars and organic acids contents, and their influence on apricot taste; and (3) to evaluate genotype and ripening stage impacts on apricot sensory and biochemical criteria.
The studied plant material included 10 apricot clones named “Boum A2,” “Agdez LG1,” “Marouch 4,” “Ab 5,” “Marouch 16,” “Rtil 4,” “Clone C,” “Mans 15,” “Agdez C2,” and “Cg 2”(Supplementary table
The experimental orchard has 184 trees gathered in a collection for a surface of 2 ha. It was planted in 1995 and used for drip irrigation. The trees were planted at a density of 4.5 × 2 m, arranged in 7 columns × 30 rows and managed with standard cultivation practices: Organic manure of 40 T/ha Major elements (NPK) equivalent to the annual needs (estimated at: N: 100–150 U/ha, P205: 80–100 U/ha; K20: 150 U/ha) An average size and thinning to adjust the load to the growth potential of the tree
The harvest was started in such a way as to optimize the compromise between optimal maturity favoring the expression of the taste quality of the fruits and the fruits aptitude for preservation in postharvest circuits. The flowering of the apricot tree is between February and March for a harvest between April and May for early cultivars and between May and June for other varieties.
All the clones were harvested at two different maturity stages (M1: commercially ripe and M2: consumption ripe) (Figure
Example of “Marouch 16” clone at two maturity stages (M1: commercially ripe and M2: consumption ripe). (a) M1-Marouch 16. (b) M2-Marouch 16.
Quantitative descriptive sensory analysis as described in the standard ISO 11035-2009 was performed. The analyses were carried out in the sensory analysis room of the Laboratory of Food Technology and Quality in the INRA, Marrakesh, established in accordance with the general guidelines for premises of sensory evaluation: ISO 8589-2007. The panel training procedure, including the sensory attributes and the scales of measures, was carried out according to a previous study [
Sensory profile of apricot clones evaluated by panelists.
Sensory criteria | Attribute |
---|---|
Unblush color | |
Blush color | |
Flesh color | |
Hardness | |
Skin hardness | |
Flesh cohesion | |
Crunchy | |
Juiciness | |
Herbaceous odor | |
Apricot flavor | |
Fruity flavor | |
Floral flavor | |
Sourness | |
Sweetness | |
Astringency | |
Bitterness | |
Persistence |
The sensory evaluations were performed according to the published apricot attributes [
Two replicates of 10 fruits for each maturity stage per clone were selected, ground, and kept at −80°C for biochemical analysis, especially soluble sugars, organic acids, and volatile compounds. The dosage was made on frozen crushed samples. For each replicate, 10 ml of distilled water is added to 2.5 g of frozen ground apricot. The preparation is homogenized and centrifuged for 10 min, at 4°C at 9000 g (Hettich 320R, Bäch, Switzerland). The supernatant is recovered after filtration on stamen. The supernatant must be diluted in order to correspond to the concentration range of the enzymatic kits.
Sugars (glucose, fructose, and sucrose) and organic acids (malic and citric acids) were quantified using an enzymatic method with kits for food analysis (R-Biopharm AG, Darmstad, Germany), especially specific enzymatic test kits for L-malic acid, citric acid, glucose/fructose, and sucrose. Results are expressed in g/kg of fresh weight for sugars and acids. These measurements were performed with a SAFAS FLX-Xenius XM spectrofluorimeter (SAFAS, Monaco) equipped with a SAFAS automatic injection device.
Volatile compounds were prepared by HS-SPME (Head space-Solid phase microextraction) using the previous method [
The SPME technique in the head space mode was used for the extraction of volatile compounds. The sampling was performed in an automated mode using the autosampler (Triplus RSH autosampler, Thermo Scientific, USA) equipped with the 75
Sample analyses were performed using a GC-MS System ISQ™ LT Single Quadrupole (Thermo Scientific, USA), equipped with a TriPlus RSH autosampler to automate SPME and a TGWAX-MS Column (30 m
Helium was used as a carrier gas with a constant column flow rate of 1 ml/min. The identification of the volatile compounds was carried out comparing mass spectral data with those of the NIST 2014 library. The Refractive Index (RI) values were also compared with those described in the literature and determined under the same conditions for matching the volatile compounds. The individual volatile compounds (identified and unidentified peaks) were tentatively quantified based on their peak areas relative to that of the internal standard (4-nonanol). Two analyses were performed for each sample. The results are expressed as 4-nonanol equivalent in
Statistical analyses were performed using the software package XLSTAT statistical software version 2011. The data were tested for differences between the clones using the one-way analysis of variance (ANOVA). The method used to discriminate among means (multiple range tests) was Fisher’s least significant difference (LSD) procedure at 95.0% confidence level. Data parameters of each apricot clone were analyzed by means of multivariate analysis employing principal component analysis (PCA) and hierarchical cluster analysis. The analytical reproducibility of the obtained data was determined as pooled standard deviations (Pooled SD). This statistical parameter was calculated for each series of replicates per variable using the sum of individual variances weighted by the individual degrees of freedom.
The apricot sensory data for each maturity stage are presented in Tables
Sensorial descriptive analysis mean scores of ten apricot clones at the commercial ripe stage (M1).
M1 | Unblush color | Blush color | Hardness | Skin hardness | Flesh cohesion | Flesh color | Herbaceous odor | Apricot flavor | Fruity flavor | Floral flavor | Juiciness | Crunchiness | Sweetness | Bitterness | Astringency | Sourness | Persistence |
---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
Marouch 16 | 4.17bc | 6.00c | 5.33ab | 6.00ab | 7.65ab | 7.17a | 4.17ab | 7.00ab | 7.50ab | 6.01abc | 4.61ab | 3.70b | 5.91abc | 1.21ab | 1.00abc | 3.50ab | 2.31abc |
Marouch 4 | 3.57cd | 6.83bc | 6.00a | 3.58d | 8.37a | 6.67ab | 3.33bc | 6.33abc | 6.33bcd | 3.83de | 5.08ab | 4.21ab | 5.65bc | 0.81b | 1.51a | 3.52ab | 2.58abcd |
Mans15 | 3.67cd | 7.17b | 7.00a | 6.69a | 5.61d | 5.70c | 4.33ab | 5.50bc | 5.33cde | 5.21bcd | 1.84d | 6.33a | 6.32ab | 1.25ab | 0.35bc | 3.81a | 1.30bcd |
Agdez C2 | 4.80abc | 5.60d | 5.60ab | 3.80d | 7.80ab | 6.40ab | 4.60ab | 6.20abc | 6.80abc | 6.25ab | 5.05ab | 3.82b | 4.77bc | 0.81b | 0.61abc | 3.53ab | 2.81ab |
RTil 4 | 4.67bc | 6.00c | 6.67a | 5.83ab | 8.27a | 6.83ab | 4.17ab | 5.19bc | 4.83de | 3.19e | 2.21cd | 4.51ab | 4.17c | 0.47b | 1.31ab | 3.47ab | 2.85ab |
Cg 2 | 2.33d | 8.00a | 5.00ab | 4.67cd | 6.44cd | 7.00a | 2.71c | 8.00a | 8.53a | 7.48a | 4.68ab | 4.66ab | 7.73a | 0.50b | 0.00c | 2.51c | 0.60d |
Clone C | 5.50ab | 5.83d | 5.83a | 3.68d | 6.61bcd | 5.50c | 4.67ab | 4.31c | 5.18cde | 4.61bcde | 5.43a | 3.31b | 3.85c | 0.81b | 1.03abc | 3.83a | 3.16a |
Boum A2 | 6.33a | 5.17d | 6.00a | 5.00c | 7.17abc | 3.71d | 5.50a | 4.57c | 4.66de | 3.30e | 4.19abc | 3.35b | 4.72bc | 2.04a | 1.34ab | 4.03a | 1.00cd |
Ab 5 | 4.50bc | 5.50d | 5.33ab | 5.60ab | 6.51cd | 5.83c | 3.00bc | 5.73bc | 5.67cde | 5.31bcd | 3.02bcd | 4.20ab | 5.18bc | 0.84b | 0.32bc | 2.65c | 1.00cd |
Agdez LG1 | 3.50cd | 6.50bc | 3.50b | 5.50ab | 7.83a | 6.67ab | 4.33ab | 4.31c | 4.30e | 4.29cde | 2.77bcd | 4.00ab | 4.18c | 0.61b | 1.53a | 3.05b | 2.00abcd |
Pooled SD | 2.4 | 3.6 | 3.2 | 3.7 | 2.3 | 3.1 | 2.2 | 2.8 | 2.5 | 3.0 | 2.0 | 1.9 | 2.3 | 0.8 | 0.8 | 1.6 | 1.4 |
Each value is the mean of 40 replicates for fresh apricot. Means with same letters within the same column do not differ significantly according to Fisher’s LSD test at
Sensorial descriptive analysis mean scores of ten apricot clones at the consumption ripe stage (M2).
M2 | Unblush color | Blush color | Hardness | Skin hardness | Flesh cohesion | Flesh color | Herbaceous odor | Apricot flavor | Fruity flavor | Floral flavor | Juiciness | Crunchiness | Sweetness | Bitterness | Astringency | Sourness | Persistence |
---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
Agdez C2 | 3.56bcd | 6.22bc | 4.43b | 2.71d | 8.00a | 6.45bc | 3.34ab | 8.11abc | 8.40ab | 7.30b | 6.67a | 2.31bc | 5.31cd | 0.39ab | 0.35ab | 2.74a | 2.23a |
Marouch 16 | 3.66bcd | 6.61bc | 3.33bc | 5.00ab | 7.33ab | 7.58ab | 3.00ab | 8.23ab | 8.25ab | 6.74bc | 6.26a | 2.33bc | 7.08abc | 0.40ab | 0.43ab | 2.30ab | 1.46ab |
Marouch 4 | 2.67cde | 7.33b | 4.00bc | 2.47d | 7.60a | 7.01abc | 2.41bc | 8.05abc | 7.77bc | 4.57d | 7.10a | 2.70b | 7.43ab | 0.68ab | 1.00a | 2.35ab | 1.06ab |
RTil 4 | 4.00bc | 6.62bc | 4.67b | 4.39bc | 7.67a | 7.69ab | 3.07ab | 7.00bcd | 6.25cd | 5.04d | 3.39b | 2.60b | 6.06cd | 0.29ab | 1.00a | 2.39ab | 1.69ab |
Mans15 | 3.00bcd | 7.23b | 6.61a | 6.00a | 5.63b | 6.39bc | 3.35ab | 6.23de | 6.31cd | 6.31bc | 3.00b | 5.00a | 7.24ab | 1.30a | 0.00b | 2.22ab | 0.42b |
Boum A2 | 5.61a | 5.43c | 4.63b | 3.29cd | 7.30ab | 3.60d | 4.00a | 6.65cde | 6.66c | 4.63d | 6.54a | 1.05c | 7.30ab | 0.35ab | 0.33ab | 2.30ab | 0.65b |
Cg 2 | 1.33e | 9.33a | 3.77bc | 3.31cd | 6.23ab | 7.61ab | 1.23c | 8.47a | 9.33a | 8.61a | 6.43a | 2.61b | 8.67a | 0.00b | 0.00b | 1.79b | 0.31b |
Clone C | 4.33ab | 6.31bc | 4.24b | 2.57d | 6.27ab | 6.47bc | 3.32ab | 5.30e | 6.43cd | 6.32bc | 6.48a | 1.35bc | 5.00d | 0.29ab | 0.00b | 2.35ab | 1.67ab |
Ab 5 | 3.70bcd | 6.67bc | 3.30bc | 4.617abc | 6.19ab | 6.33c | 2.40bc | 6.61cde | 6.23cd | 5.67cd | 3.65b | 2.67b | 6.51bcd | 0.35ab | 0.00b | 1.60b | 0.40b |
Agdez LG1 | 2.34de | 7.30b | 2.55c | 3.44bcd | 7.67a | 8.00a | 2.59abc | 5.33e | 5.00d | 4.60d | 3.61b | 2.43bc | 5.55cd | 0.00b | 0.61ab | 1.00c | 0.41b |
Pooled SD | 2.7 | 2.6 | 1.8 | 2.2 | 1.7 | 3.2 | 2.9 | 3.1 | 2.2 | 1.7 | 3.0 | 2.7 | 2.4 | 0.8 | 0.5 | 1.2 | 1.1 |
Each value is the mean of 40 replicates for fresh apricot. Means with same letters within the same column do not differ significantly according to Fisher’s LSD test at
The evaluation by panel experts proved that apricot clones in the M2 stage had good characteristics for fresh consumption because of the high intensities of key attributes, especially fruity flavor (9.33) and sweetness (8.67) registered for “Cg 2.” Regarding both the maturity stages (M1 and M2), different patterns were found, and different attributes levels were obtained for the studied apricot clones. Indeed, the ripening had a marked impact on the sensory characteristics of apricots. The sensory scores of lightness, skin hardness, hardness, bitterness, astringency, herbaceous odor, crunchiness, sourness, and persistence were higher in the M1 stage for all apricot clones (Table
Blush color, skin hardness, fruity flavor, and sweetness were the attributes that best explain the difference between the studied clones (Figure
Among the studied apricots, “Cg 2” was the most appreciated clone, followed by “Marouch 16” and “Agdez C2” (Figure
Main sensory attributes differentiating between clones at the commercial maturity (M1) and consumption (M2) stages.
The multivariate analysis revealed that, for both stages of maturity, soluble sugars and organic acids of the ten apricot clones are significantly different (
The sugars and organic acids contents of the studied apricot clones are given in Figure
Soluble sugars and organic acid contents of ten apricot clones at commercial ripe (M1) and consumption ripe (M2) stages. The error bars represent the standard deviation of each replicate per maturity stage per clone. The means with same letters do not differ significantly according to Fisher’s LSD test at
Concerning organic acids, the major ones are malic and citric acids (Figure
In this study, citric acid was predominant for 8 apricot clones over 10 at the commercial stage (M2). For the ripest fruits, citric acid remains highly predominant for 4 clones (“Boum A2,” “Clone C,” “Agdez LG1,” and “Ab 5”), malic acid being the major acid for red clones (“Mans 15” and “Cg 2”) and “Marouch 4.” The perception of citric acid was higher than that of malic acid. Containing three ionizable hydrogens per molecule, the citric acid is known for a bright, tart flavor that dissipates quickly with ripening. This acid pairs well with fruit flavors, especially citrus [
For most studied clones, it is observed that the concentration of organic acids tends to decrease and the sugar content increases with maturity. However, these trends were weak compared with the study of Ayour et al. [
The volatile compounds identified in the studied apricot clones and their concentrations for commercial and consumption stages are listed in Tables
Concentration (in
Volatile compounds | RI | “Mans 15” | “Cg 2” | “Ab 5” | “Agdez C2” | “Marouch 4” | “Rtil 4” | “Clone C” | “Marouch 16” | “Agdez LG1” | “Boum A2” |
---|---|---|---|---|---|---|---|---|---|---|---|
Acetaldehyde | 831 | 143.2 ± 24.3a | 150.5 ± 46.8a | 119.5 ± 26.0a | 22.6 ± 5.3b | 145.2 ± 30.3a | 184.3 ± 43.1a | 187.4 ± 35.2a | 105.2 ± 19a | 91.4 ± 17.3ab | 57.7 ± 11.8b |
Hexanal | 1102 | 398.2 ± 66.5b | 147.7 ± 27.3d | 417.7 ± 51.3a | n.d | 182.3 ± 22.6d | 90.2 ± 11.9e | 282.7 ± 30.1c | 87.2 ± 10.5e | 125.3 ± 11.3d | 83.5 ± 11.6e |
Pentanal | 1153 | 97.0 ± 20.4ab | 69.8 ± 14.5b | 32.5 ± 7.6b | 110.4 ± 23.6a | 111.8 ± 19.3a | 98.7 ± 24.6ab | 131.7 ± 34.6a | 46.9 ± 12.5b | 137.6 ± 34.6a | 25.5 ± 9.5b |
2-Hexenal | 1249 | 321.3 ± 45.6a | 106.5 ± 20.5b | 345.6 ± 50.1a | 92.6 ± 34.7bc | 64.6 ± 17.8c | 56.0 ± 18.9c | 71.2 ± 27.6c | 31.7 ± 12.1c | 12.7 ± 6.5c | 49.8 ± 15.5c |
Butanal-2-methyl | 1257 | 15.1 ± 7.8b | n.d | 30.2 ± 10.1b | n.d | 24.6 ± 7.6b | 89.8 ± 22.7a | 7.4 ± 2.8b | 28.8 ± 15.6b | 17.0 ± 4.6b | 16.2 ± 7.0b |
Butanal-3-methyl | 1267 | 30.9 ± 12.2b | 82.0 ± 20.5a | 17.1 ± 7.6b | n.d | 14.1 ± 5.5b | n.d | n.d | 13.4 ± 3.9b | 4.8 ± 1.1b | 18.7 ± 7.7b |
Benzaldehyde-4-methyl | 1288 | 13.8 ± 4.5b | 36.2 ± 10.5a | 66.8 ± 18.8a | 17.3 ± 3.6b | 65.7 ± 17.7a | 8.4 ± 2.5b | 13.5 ± 3.7b | 6.8 ± 1.7b | 4.1 ± 0.8b | n.d |
Benzaldehyde | 1536 | 40.5 ± 10.6b | 136.9 ± 30.2a | 139.9 ± 23.6a | 43.0 ± 11.7b | 90.0 ± 23.0ab | 40.0 ± 11.7b | 33.6 ± 15.5b | 13.5 ± 3.8b | n.d | n.d |
1651 | 23.9 ± 7.7ab | 32.5 ± 8.0a | 76.7 ± 23.8a | 11.3 ± 1.7b | 38.6 ± 11.0a | 13.2 ± 3.9b | 22.5 ± 7.8ab | 21.2 ± 3.7ab | 16.5 ± 4.3b | 27.6 ± 7.7ab | |
2-Propanone | 866 | 18.0 ± 7.8d | 217.9 ± 43.8a | 13.5 ± 3.2d | 13.3 ± 3.6d | 2.2 ± 0.7d | 14.4 ± 6.5d | 104.5 ± 25.5b | 5.03 ± 1.1d | 251.9 ± 77.9a | 60.2 ± 22.2c |
1973 | 23.9 ± 7.2b | 32.5 ± 8.9b | 76.7 ± 22.6a | 14.3 ± 6.4b | 38.6 ± 12.3b | 13.2 ± 5.4b | 22.5 ± 6.7b | 21.2 ± 7.1b | 16.5 ± 4.7b | 27.6 ± 10.5b | |
6-Methyl-5-hepten-2-one | 1982 | 2.9 ± 0.6a | n.d | 5.9 ± 2.7a | n.d | 11.8 ± 5.5a | 2.4 ± 0.8a | 2.3 ± 0.7a | 4.4 ± 0.7a | n.d | 1.1 ± 0.1a |
3-Hydroxybutanone | 1998 | 75.8 ± 20.0b | 6.9 ± 1.7c | 7.2 ± 2.4c | 74.7 ± 11.7b | 7.8 ± 1.9c | 177.4 ± 65.8a | 7.9 ± 3.0c | 8.3 ± 2.7c | 3.3 ± 1.6c | 2.1 ± 0.5c |
2134 | 12 ± 27.0a | 168.0 ± 31.1a | 111.0 ± 39.2a | 105.0 ± 26.7a | 102.0 ± 32.9a | 138.0 ± 40.0a | 87.0 ± 22.1b | 153.0 ± 61.0a | 123.0 ± 44.0a | n.d | |
Ethanol | 955 | 323.8 ± 44.7a | 93.7 ± 12.0bc | 33.1 ± 8.7c | 80.2 ± 28.7bc | n.d | 150.9 ± 38.2b | 161.2 ± 33.2b | 70.1 ± 18.9c | 43.3 ± 17.1c | 71.6 ± 27.9c |
1-Butanol | 1115 | 30.4 ± 12.6a | 12.1 ± 1.4a | 25.2 ± 9.1a | 58.1 ± 17.2a | 28.7 ± 13.2a | 16.8 ± 4.6a | 22.2 ± 7.7a | 34.0 ± 11.0a | 21.1 ± 7.1a | 3.1 ± 1.8a |
1-Penten-3-ol | 1156 | 13.6 ± 3.5a | n.d | n.d | n.d | 6.7 ± 2.7a | 4.3 ± 1.2a | n.d | n.d | n.d | n.d |
1-Hexanol | 1207 | 48.5 ± 14.5a | 41.0 ± 10.1a | 10.2 ± 1.2a | 33.2 ± 6.9a | 3.8 ± 0.8a | 47.2 ± 11.5a | 4.8 ± 0.7a | 6.2 ± 1.6a | n.d | 3.3 ± 1.7a |
2-Hexen-1-ol | 1367 | 56.2 ± 21.0a | 21.7 ± 8.9a | 16.4 ± 4.9a | 58.7 ± 16.8a | 7.5 ± 2.6a | 21.5 ± 5.4a | 17.2 ± 2.5a | 5.6 ± 2.1a | n.d | 6.2 ± 3.1a |
1432 | 63.5 ± 17.9e | 217.0 ± 90.1c | 880.5 ± 153.7a | 60.0 ± 17.9e | 351.3 ± 61.1b | 100.1 ± 20.0d | 31.2 ± 6.2e | 9.2 ± 2.1e | 40.1 ± 11.7e | 95.2 ± 24.9d | |
1-Butanol-2-methyl | 1444 | 31.4 ± 5.7a | n.d | n.d | 38.6 ± 8.8a | n.d | n.d | n.d | n.d | n.d | n.d |
Methyl acetate | 912 | 68.9 ± 12.5a | 80.7 ± 21.2a | 46.0 ± 8.3b | 46.0 ± 11.8b | 46.3 ± 13.8b | 74.5 ± 15.8a | 28.5 ± 8.5b | 30.8 ± 6.0b | n.d | 12.9 ± 4.2b |
Butylacetate | 1165 | 16.1 ± 7.9b | n.d | n.d | 63.7 ± 17.7a | n.d | n.d | n.d | 22.8 ± 7.9b | 30.5 ± 12.1b | n.d |
3-Hexen-1-ol acetate | 1287 | 56.9 ± 17.0a | 9.1 ± 1.9b | 7.1 ± 2.1b | 29.5 ± 5.7b | 4.0 ± 1.7b | 3.1 ± 1.2b | 4.5 ± 2.1b | n.d | n.d | 2.8 ± 0.2b |
2-Hexen-1-ol acetate | 1331 | 66.3 ± 12.4a | 33.7 ± 6.9b | n.d | 33.3 ± 12.1b | n.d | 7.6 ± 3.3b | n.d | n.d | n.d | n.d |
Acetic acid | 1478 | 54.4 ± 12.5b | 57.5 ± 15.9b | 63.9 ± 15.0b | 112.2 ± 37.8a | 68.9 ± 15.8b | 29.9 ± 12.1b | 65.7 ± 15.7b | 28.5 ± 7.9b | 53.3 ± 15.2b | 16.3 ± 3.5b |
Values are means ± standard deviation (SD) of two replicates of 10 fruits for each maturity stage (M1 and M2) per clone. n.d: not detected. Means with same letters within the same line do not differ significantly according to Fisher’s LSD test at
Concentration (in
Volatile compounds | RI | “Mans 15” | “Cg 2” | “Ab 5” | “Agdez C2” | “Marouch 4” | “Rtil 4” | “Clone C” | “Marouch 16” | “Agdez LG1” | “Boum A2” |
---|---|---|---|---|---|---|---|---|---|---|---|
Acetaldehyde | 831 | 99.8 ± 16.5b | 208.4 ± 28.2a | 98.2 ± 12.1b | 141.3 ± 38.2b | 133.4 ± 20.1b | 229.0 ± 32.4a | 180.0 ± 30.2ab | 154.4 ± 31.2b | 122.0 ± 17.5b | 31.6 ± 7.4c |
Hexanal | 1102 | 124.3 ± 23.5d | 201.5 ± 33.3c | 696.3 ± 77.8a | 203.0 ± 37.5c | 490.8 ± 44.3b | 190.1 ± 39.2d | 158.8 ± 29.9d | 15.4 ± 3.5e | 93.7 ± 11.1de | 110.2 ± 20.4d |
Pentanal | 1153 | 522.5 ± 70.1a | 78.5 ± 26.4c | 164.0 ± 40.3b | 117.4 ± 25.5b | 12.0 ± 3.5d | 107.6 ± 24.6b | 76.8 ± 11.5c | 61.4 ± 21.5c | 33.8 ± 10.6d | 69.1 ± 18.5c |
2-Hexenal | 1249 | 102.2 ± 34.5b | 135.9 ± 31.7b | 404.7 ± 61.5a | 46.3 ± 18.0c | 422.0 ± 82.3a | 78.7 ± 22.6c | 43.8 ± 14.9c | 9.0 ± 4.5c | 51.1 ± 18.7c | 23.0 ± 8.5c |
Butanal-2-methyl | 1257 | 19.6 ± 8.6a | n.d | 2.5 ± 0.7a | n.d | 24.3 ± 8.3a | 16.3 ± 6.8a | 14.8 ± 5.1a | n.d | 20.4 ± 4.6a | 22.7 ± 7.9a |
Butanal-3-methyl | 1267 | 6.7 ± 1.4b | 107.9 ± 26.7a | n.d | n.d | 6.8 ± 2.2b | 8.9 ± 1.6b | n.d | 18.9 ± 5.5b | 3.1 ± 0.6b | 7.5 ± 0.8b |
Benzaldehyde-4-methyl | 1288 | 14.7 ± 3.5a | 47.8 ± 15.6a | 34.4 ± 11.8a | 33.3 ± 11.4a | 30.5 ± 9.9a | 20.4 ± 4.4a | 10.9 ± 2.6a | 18.2 ± 6.1a | 2.0 ± 0.2a | 9.0 ± 1.7a |
Benzaldehyde | 1536 | 55.9 ± 21.5b | 189.0 ± 38.1a | 27.8 ± 3.7b | 82.6 ± 18.9b | 70.7 ± 11.5b | 49.8 ± 12.5b | 27.5 ± 10.6b | 54.3 ± 16.9b | n.d | n.d |
1651 | n.d | 20.6 ± 3.7a | 27.7 ± 11.5a | 16.4 ± 3.9a | 58.8 ± 23.7a | 21.7 ± 5.7a | 17.5 ± 4.7a | n.d | 32.2 ± 7.9a | 21.4 ± 8.2a | |
2-Propanone | 866 | 18.7 ± 8.5c | 367.7 ± 87.9a | 5.5 ± 1.4c | 124.2 ± 40.1b | 32.2 ± 7.5c | 5.6 ± 2.3c | 29.2 ± 11.1c | 5.6 ± 2.0c | 119.4 ± 44.4b | 74.8 ± 13.8c |
1973 | n.d | 70.6 ± 27.7a | 27.7 ± 11.1a | 16.4 ± 3.5a | 58.8 ± 14.8a | 21.7 ± 7.9a | 17.5 ± 5.9a | n.d | 32.2 ± 10.0a | 21.4 ± 5.7a | |
6-Methyl-5-hepten-2-one | 1982 | 14.8 ± 3.8a | n.d | 4.1 ± 1.3a | 1.5 ± 0.4a | 11.9 ± 5.0a | 77.7 ± 20.1a | 9.2 ± 2.9a | n.d | n.d | n.d |
3-Hydroxybutanone | 1998 | 174.6 ± 38.7b | 12.0 ± 2.7c | 411.3 ± 99.1a | 12.5 ± 5.8c | 4.0 ± 1.3c | 10.8 ± 3.7c | 16.8 ± 4.7c | 195.4 ± 22.6b | 3.7 ± 1.6c | 1.6 ± 0.9c |
n.d | n.d | n.d | n.d | n.d | n.d | n.d | n.d | n.d | n.d | n.d | |
Ethanol | 955 | 429.7 ± 79.9a | 165.2 ± 66.5c | 242.0 ± 50.8b | 196.1 ± 39.6bc | n.d | 253.9 ± 57.9b | 283.1 ± 54.1b | 402.6 ± 92.7a | 41.6 ± 15.0d | 183.7 ± 58.9c |
1-Butanol | 1115 | 58.4 ± 19.4b | 26.1 ± 5.6b | 12.8 ± 1.6b | 31.9 ± 11.0b | 24.3 ± 8.4b | 69.8 ± 14.6b | 114.0 ± 26.8a | 27.5 ± 8.5b | 6.5 ± 2.8b | 13.2 ± 3.9b |
1-Penten-3-ol | 1156 | n.d | n.d | 9.9 ± 3.7a | n.d | n.d | n.d | n.d | n.d | n.d | n.d |
1-Hexanol | 1207 | 81.1 ± 22.2a | 61.5 ± 11.5a | 86.0 ± 20.0a | n.d | 9.2 ± 2.6b | n.d | 19.5 ± 3.1b | 68.7 ± 12.5a | n.d | n.d |
2-Hexen-1-ol | 1367 | 40.0 ± 12.1b | 17.7 ± 2.8b | 63.9 ± 15.8a | 17.4 ± 12.5b | 23.2 ± 3.9b | 4.1 ± 0.7b | 8.7 ± 2.8b | 22.6 ± 4.6b | 4.8 ± 1.9b | n.d |
1432 | 8.5 ± 1.7d | 283.5 ± 80.2b | 78.2 ± 21.9d | 25.7 ± 7.1d | 728.4 ± 169.2a | 221.1 ± 41.9b | 15.8 ± 3.7d | 49.9 ± 13.9d | 236.6 ± 42.0b | 112.0 ± 30.0c | |
1-Butanol-2-methyl | 1444 | 146.4 ± 49.2a | n.d | n.d | n.d | n.d | n.d | 52.0 ± 13.7b | n.d | n.d | n.d |
Methyl acetate | 912 | 115.9 ± 27.2a | 35.5 ± 7.4b | 38.9 ± 6.9b | 53.7 ± 12.0b | 35.2 ± 8.2b | 49.7 ± 14.9b | 46.1 ± 9.7b | 101.2 ± 29.2a | 21.7 ± 4.9b | 10.8 ± 2.6b |
Butylacetate | 1165 | 145.7 ± 41.2a | n.d | n.d | 64.9 ± 8.2b | n.d | 49.0 ± 8.2b | 69.3 ± 17.8b | n.d | n.d | 19.1 ± 2.7b |
3-Hexen-1-ol acetate | 1287 | 156.8 ± 30.2a | 6.3 ± 2.4b | 46.7 ± 12.7b | 9.5 ± 2.3b | 3.3 ± 0.7b | 5.3 ± 2.2b | n.d | 4.2 ± 1.1b | 3.8 ± 0.7b | n.d |
2-Hexen-1-ol acetate | 1331 | 71.3 ± 21.9a | 48.3 ± 11.0b | 38.6 ± 11.1b | 11.5 ± 3.3c | 4.1 ± 0.7c | n.d | n.d | 6.4 ± 2.6c | n.d | n.d |
Acetic acid | 1478 | 56.5 ± 11.6b | 63.8 ± 12.8b | 121.8 ± 18.5a | 64.6 ± 10.5b | 54.2 ± 8.2b | 49.4 ± 15.0b | 47.4 ± 10.2b | 53.4 ± 18.1b | 20.6 ± 5.2b | 37.0 ± 8.9b |
Values are means ± standard deviation (SD) of two replicates of 10 fruits for each maturity stage (M1 and M2) per clone. n.d: not detected. Means with same letters within the same line do not differ significantly according to Fisher’s LSD test at
The volatile profiles indicated qualitative and quantitative differences (
Highest concentrations were found for hexanal in both M1 and M2 stages. A previous study reported that hexanal and 2-hexenal are abundant in Turkish apricots where they are the major aldehydes. The concentration of hexanal in some of these cultivars varied from 28.4 to 1475.3
The ketones represent the third volatile compounds group. Among these ketones, 3-hydroxy-2-butanone was the most abundant. These results are in agreement with those reported by Ndomo et al. [
Compared to the other classes of volatiles compounds, the acids group had the lowest abundance, which is in agreement with other studies [
Based on volatiles quantification results, among all apricot clones, “Agdez C2,” “Ab 5,” “Cg 2,” and “Mans 15” were determined with the highest concentration levels in both the maturity stages. However, compared to the literature, most studied apricot clones are rich in aromatic compounds according to their volatile compound contents at two different stages of maturity.
The comparison between sensory attributes, organic acids, and soluble sugars showed significant correlations. Two groups of sensory characteristics were identified: a first group of positively correlated attributes consisting of lightness, firmness, sourness, bitterness, astringency, herbaceous odor, crunchiness, and acidity persistence and a second group of correlated attributes constituted by blush color, sweetness, apricot flavor, fruity flavor, floral flavor, and juiciness. However, both the groups are negatively correlated.
In addition, good correlations appeared between some sensory attributes and the biochemical measurements, especially between color attributes and reducing sugars (glucose and fructose). The first group of attributes (named the sour group) was negatively correlated with glucose and fructose, positively correlated with citric acid, and vice versa for some attributes of group 2 (named sweet group) which were positively correlated with soluble sugars (glucose and fructose) and negatively with organic acids, especially citric acid. These results are consistent with a previous study which showed that perceptions of sugar and acidity interfered heavily in apricots. In fact, the more firm an apricot is, the more acidic it will be considered and slightly sweet, which depends on ripening and genotype impacts. It has also been shown that the perception of sweet taste depends not only on the soluble sugars content but also on acidity and firmness of apricot fruit [
In relation with the evolution of radars maps between the two maturity stages, a very strong effect of the ripening stage was observed noticed with the strongest correlations: positive between the three color attributes, the sweetness, and the juiciness and negative with the texture criteria (strongly correlated with each other). These correlations explain the processes of the loss of firmness and, therefore, the softening of the fruit, the degradation of chlorophylls, the accumulation of carotenes, and the increase of sugars during maturation. Moreover, the three tested flavors (apricot, fruity, and floral) were positively correlated with each other and negatively correlated with the herbaceous flavor, which is explained by the evolution of the aroma during the maturity.
Principal component analysis was performed between studied variables. The observed variability of 53.82% was explained by the first two principal components (F1 and F2) (Figure
Principal component analysis (PCA) of volatile compounds and the sensory profile of apricot clones. (a) Correlation circle of sensory attributes, soluble sugars, organic acids, and volatile compounds. (b) Segregation of the apricot clones based on the studied parameters depending on maturity stages (M1: commercial ripe; M2: consumption ripe).
However, most volatile compounds were better discriminated by the F2, which opposed 2-hexenol (
The apricot samples were harvested at different time intervals depending on the degree of ripening (M1: commercial and M2: consumption). In fact, the factorial representation of the sensory profile depends to the concentrations of volatile compounds whish also depend on a series of physical and biochemical changes during maturation [
Regarding apricot clones, the orange (especially “Ab 5,” “Marouch 4,” and “Marouch 16”) and the red ones (“Mans 15,” “Cg 2”) are most rich in volatile compounds in both maturity stages. “Ab 5” was rich in apricot flavors and characterized with a balance of volatile compounds (qualitatively and quantitatively). “Cg 2” is characterized by a good acid-sugar balance regarding its composition in soluble sugars and organic acids. Also, “Cg 2” represents the genotype least affected by maturation, and this shows a sensory quality of this clone that could be the issue of fruit valuation for a longer maturation period of apricots.
Gokbulut and Karabulut [
For a tasty fruit like apricot, quality is defined by the perception of several criteria broken down and dissected using sensory and biochemical indicators. The ten studied Moroccan clones have very promising and interesting sugars and organic acids contents and sensory profiles, leading to reasonably good overall fruit quality. This study also highlighted that soluble sugars and organic acids are important biochemical parameters for the sensory perception of apricot fruit. The principal component analysis revealed that the maturity stage has a significant impact in determining the perception of sensory quality related to biochemical parameters. Red apricots were among the recommended cultivars for the cultivation and for apricots consumption as fruits, especially “Cg 2” which was considered the most flavorful and aromatic clone, followed by “Marouch 4,” “Agdez C2,” “Mans 15,” “Ab 5,” and “Rtil 4” which were characterized with good sensory attributes at the consumption stage (M2). In addition, all clones were characterized in this study by very interesting sensory attributes and sugar-acid balances expressing a good overall quality of the fruits. The excellent quality properties of these clones, as well as the criteria associated with the ripening stages, certainly represent valuable genetic characteristics for extending the harvesting season of good quality apricots in Morocco and in all Mediterranean regions.
The data (experiences, analyses, and results) used to support the findings of this study are included within the article and in other published articles. A prior study was cited at relevant places within the text as reference [
The authors declare that there are no conflicts of interest regarding the publication of this paper.
The authors are grateful to the technical staff of the INRA SQPOV Research Unit (Avignon, France) and the INRA Laboratory of Agri-Food Technology and Quality and of the INRA Saâda Experimental Field (Marrakesh, Morocco) and to the INRA Fruits Sensory Panel (Marrakesh, Morocco) for their precious collaboration in the development of this work. This research was performed as part of the research activities of the Regional Center for Agricultural Research in Marrakesh belonging to the National Institute for Agricultural Research (INRA Morocco). It was also supported by the grant of the Moroccan Ministry of National Education, Professional Training, Higher Education, and Scientific Research attributed to author Jamal Ayour in the framework of the doctoral studies.
Supplementary TABLE 1: morphological characteristics of the studied ten apricot clones.