The general and volatile properties and the quality of two newly selected Satsuma clones (11/1 İzmir and 30/ İzmir) grown under Mediterranean ecological conditions

of this study was to better understand the quality and the general properties of the newly selected 30/İzmir and 11/1 İzmir Satsuma clones in the light of general and volatile compound analysis. This work will help to optimize the cultivation of these new cultivars in order to achieve the best flavor and the best quality and provide valuable data for new breeding programs related to these two clones. Abstract The general and volatile properties, and the quality of two new Satsuma clones – 11/1 İzmir and 30/İzmir – selected under a Citrus Bud Wood Selection Program, were compared with Dwari Satsuma samples grown under Adana ecological conditions. Gas chromatography, mass spectrometry, flame ionization detection (GC/MS/FOD) analysis was used in the identification and quantification of the aromatic compounds, and a sensory profile analysis was performed to complete the general understanding using chemical analysis. The general analysis showed that the clone samples have higher yields, are more intense in skin color and more acidic; however, the total soluble solids and total sugar amount are lower than the Dwari Satsuma samples. The terpenes are the major aromatic compound class. Along with other terpenes, there were significant amounts of dl-limonene followed by γ-terpinene, β-elemene, linalool and α-terpineol. The sensory analysis showed that the Dwari Satsuma samples are sweeter and riper, with a better floral, spicy-citrus flavor than both clones. Both clones had a lower “Dverall liking” rating than the Dwari Satsuma samples.


Introduction
The mandarin has a popular place among citrus fruits and is normally freshly consumed. Ot has a characteristically elegant flavor, smaller in size by comparison to an orange or grapefruit and can be easily peeled (Plotto et al., 2011). There has been a global increase in demand for easy-to-peel fresh citrus fruits. Satsuma mandarins (Citrus unshiu Marc.) have been grown primarily for fresh consumption due to early ripening, their ease of peeling, because they are seedless and low acidic tasting with a refreshing aroma.
Even though the citrus fruits' natural genetic center isn't Turkey, these fruits have been produced in this country for decades. To find new Satsuma varieties that have the properties to meet market demands for a high yield, the First National Citrus Bud Wood Selection Program was implemented in the Aegean and Mediterranean regions of Turkey beginning in 1979 by Özsan et al. (1986). That project searched the regions for trees with a high yield, that were free from disease and that produced a high quality crop every 4 years (Özsan et al., 1986). The main purpose of that study was to determine the variations in some selected agronomical traits of 21 Satsuma mandarins derived from selection breeding programs and to characterize them by Simple sequence repeats (SSR) and Random Amplification of Polymorphic DNA (RAPD) genetic markers. The project succeeded in determining the variations in the selected agronomical traits and genetic markers from the 21 new Satsumas identified from previous research (İncesu et al., 2011). From this research project, two new clonesI: namely 30/İzmir and 11/1 İzmir selected from the Aegean region -out of the selected 21 Satsuma clones -were declared to have better fruit quality and a higher yield than the Dwari Satsuma samples under Adana ecological conditions (İncesu et al., 2011).
The aim of this study was to better understand the quality and the general properties of the newly selected 30/İzmir and 11/1 İzmir Satsuma clones in the light of general and volatile compound analysis. This work will help to optimize the cultivation of these new cultivars in order to achieve the best flavor and the best quality and provide valuable data for new breeding programs related to these two clones.

Materials
The 30/İzmir clone, 11/1 İzmir clones and the Dwari Satsuma (control sample) were obtained from the Çukurova University Citrus Genetic Resources orchard in Adana, Turkey. Fruits were Practical Application: For the first time this study focuses on the quality of two Satsuma clones, which were declared to have better fruit quality and a higher yield than the Dwari Satsuma in the National Citrus Bud Wood Selection Program. This study investigates the fruit quality characteristics of these recommended clones to understand whether cultivation of these clones is appropriate or not. According to our analytical results, the Dwari Satsuma was declared to have a better fruit quality than the clones, whereas the clones are more efficient in terms of yield.
harvested at the commercially ripe stage from 25-year-old trees. Analytical grade chemicals and commercial reference aromatic compounds were used in the analyses.

Methods
The samples were weighed and digital calipers were used for diameter measurements. A standard juicer was used for fruit juice extraction prior to weighing, and the result expressed as a fruit juice content percentage (FJC). A portable refractometer (Atago-Japan) was used to determine the total soluble solids content (TSS). The titratable acidity (TA) of the mandarin samples was measured by titration of 5 mL of the juice sample with 0.1 N of sodium hydroxide (NaDH) until a pH of 8.2 was reached and then expressed as a percentage equivalent of citric acid.
The skin color measurement of samples was performed on ten mandarins for each treatment. The average value of two measurements at equidistant points around the equatorial circumference of the fruits was used for each evaluation. A colorimeter (Minolta CR 300, Konica Minolta, Tokyo, Japan), after calibrating against a white tile, was used for the colorimetric evaluation and the results were expressed as the Hue angle (ho) [arctangent (b*/a*)] (McGuire, 1992). For citric acid and sugar analysis, 1 mL of mandarin juice was diluted to 10 mL with ultrapure water followed by centrifuging at 10,000 × g at 4 °C for 20 minutes. The samples were filtered through a 0.45 μm cellulose-acetate membrane and then directly injected into high-performance liquid chromatography (HPLC) equipment with an Aminex HPX-87H column and a refractive index detector (Shimadzu-Japan). The mobile phase was 0.005 N H2SD4 at a flow rate of 0.5 mL min −1 . The presence and amount of citric acid and sugars (fructose, glucose and sucrose) were calculated by comparing sample peak areas against standards.
For the determination of the aromatic compounds, the liquid-liquid extraction method -commonly used for plant products -was used, and the solvent dichloromethane (CH 2 Cl 2 ) was used for extraction of hand-peeled mandarin samples. GC-MS-FOD analysis was carried out using an Agilent 6890 N-5973 N GC-MS-FOD. A J&W fused silica DB-wax capillary column (60 m, 0.25 OD, 0.25 film) was used during the analyses, and the NOST © and Wiley © flavor libraries were used for the identification of the aromatic compounds (Schneider et al., 1998).
Dn the day of the sensory panel test, 10 mandarin fruits from each clone were peeled and segmented. The fruit segments were separated, cut in half, and then put in a bowl to guarantee that each assessor evaluated parts of various fruits. Ten mixed segmented half fruits were served in identical clear glass cups. Evaluation sessions took place in a sensory room at ambient temperature under daylight at the Department of Horticulture (University of Çukurova). Unsalted crackers and filtered water were provided to panelists to cleanse their palate between samples. For each sample, panelists evaluated each descriptor on a horizontal unstructured scale of 10 cm. The marks given for each descriptor by all panelists were summed up and an average value was used for a spider web diagram ( Figure 1).

Statistical analysis
The statistical analysis used for the data was one-way analysis of variance (ANDVA). Duncan's multiple-range tests were used to compare the significant differences of the mean values with the family error rate held at 0.05. The statistical analyses were performed using SPSS © statistics software version 18.0 (SPSS Onc., Chicago, OL, USA).

General composition of mandarins
The chemical composition of the Dwari Satsuma and the clones are given in Table 2. The Dwari Satsuma juice showed a higher concentration of total soluble solids than both clones, whereas the total soluble solids in the 30/İzmir clone was slightly higher than the 11/1 İzmir clone. Sugars are the main constituents of fruit juices, especially citrus juices. According to the total sugar levels, the Dwari Satsuma sample had higher values than the 11/1 İzmir clone, and the 30/İzmir clone had the lowest total sugar level. Sucrose is known as the major sugar translocated in a plant, and it can be degraded by cell-wall sucrose synthase to glucose and fructose (Yu et al., 2015). The sucrose and the glucose levels were higher in the Dwari Satsuma sample than the 11/1 İzmir clone, and the 30/İzmir clone had the lowest level. The fructose level of the 11/1 İzmir clone and the Dwari Satsuma were very close to each other at about 20.2 g/kg, whereas the 30/İzmir clone had a fructose level of 14.86 g/kg. Both organic acids and sugars are regarded as significant quality factors by customers and the food industry. The 30/İzmir clone had the highest total acidity amount, followed by the 11/1 İzmir clone and then the Dwari Satsuma sample, respectively. On particular, citric acid is the main organic acid in citrus fruit juice. Yun et al. (2010) found that citric acid made up to 90% of the total organic acid content throughout the entire postharvest period (Yu et al., 2015). According to citric acid levels, the Dwari Satsuma sample is the least acidic sample followed by the 11/1 İzmir clone, whereas the 30/İzmir clone had the highest citric acid level.
The color of a fruit or fruit juice is the first quality factor that the consumer notices, and it has an important influence on consumers' preferences (Cortés et al., 2008). The skin color values of the clones were similar and/or higher than the Dwari Satsuma. On Clemenules mandarin samples, Pérez-López et al. (2007) found the hue angle to be between 72.89 and 73.75, which is in agreement with the color properties of the mandarin clone samples examined in this study. The yield amount is also one of the most important properties for citrus fruits. The 30/İzmir had a slightly higher fruit juice content (FJC) than 11/1 İzmir, where both clones showed a higher FJC than the Dwari Satsuma sample ( Table 2). The fruit weight (g) and diameter of (mm) the Dwari Satsuma sample and the clone samples are shown in Table 3. Ot can be said that clone samples are bigger than Dwari Satsuma as fruit weight and diameter. According to the general analysis, the clone samples had higher yields, greater color intensity and more acidity, but the total soluble solids and total sugar amount was lower than the Dwari Satsuma sample.
The β-elemene concentration was reported to be 230 μg/L in the Dwari Satsuma by Ren et al. (2015). C6 volatile compounds, which were products of the enzymatic breakdown of unsaturated fatty acids like Hexanal, (E)-2-hexenal, (Z)-3-hexanal and 2-hexanol, were the greatest in the 30/İzmir clone sample, followed by the 11/1 İzmir clone and were smallest in the Dwari Satsuma sample. These compounds were primarily responsible for the green odor. Esters, which contribute to the strong fruity and floral odor of fruits were the highest in the Dwari Satsuma sample. Aldehydes are most likely the enzymatic degradation products of unsaturated fatty acids such as oleic, linoleic and linolenic acids (Qiao et al., 2008). For orange fruit, according to Perez-Cacho & Rouseff (2008), aldehydes are formed during the ripening and maturation period, and their concentration increases with fruit maturity. The 30/İzmir clone had the highest aldehyde content (206 µg/L), whereas the Dwari Satsuma and the 11/1 İzmir clone has 85 µg/L and 86 µg/L of aldehyde content, respectively. These compounds give a more mature flavor, and this will affect the fresh mandarin taste of the 30/İzmir clone. Both clones were found to be more efficient in maximizing the juice amount and sugar potential, but their flavor qualities seemed to be diluted. Aromatic compounds have a strong relationship with yield. There are references about this relationship in some other fruits which shows aroma decreasing with increasing yield (in grape, Jackson &Lombard, 1993, andin mango fruit, Léchaudel &Joas, 2007.)

Sensory evaluation
The sensory profile analysis is presented in Table 5 and the spider web diagram for the data is shown in Figure 1.
The evaluation of both clones shows similar profiles. The Dwari Satsuma sample had the highest sweetness and floral, citrusy, attractive spicy flavor and the highest total quality values, followed by the 30/İzmir and 11/1 İzmir clones, respectively. The sourness of both the 11/1 İzmir and 30/İzmir clones is high compared to the Dwari Satsuma sample, which affected the total quality scores (Figure 1).

Conclusions
This study investigated the aromatic compounds of two newly selected Satsuma clones, namely 11/1 İzmir and 30/İzmir cultivars, against the Dwari Satsuma. The organic terpene compounds were the main volatile components in all samples. Both the terpene and the total aromatic compound concentrations of the Dwari Satsuma sample was higher than the newly selected clones. The dl-limonene was the most abundant component in all samples followed by γ-terpinene. Thus, the Dwari Satsuma sample is richer in terpenes, with its fresh piney and citrus aroma, than the clones. With regard to the chemical and instrumental analyses, the sensory analysis of the Dwari Satsuma sample is sweeter and riper, with a better floral, spicy-citrus flavor than both the clones. The sourness is balanced in the Dwari Satsuma sample. The 11/1 İzmir and 30/İzmir clones were both similar but with less sweetness and higher sourness values than the Dwari Satsuma sample. The 30/İzmir clone has the highest bitterness values and greater citrus and spicy flavor values then the 11/1 İzmir clone. There is a clear correlation between the aromas and perceived flavor of the studied samples. The 30/İzmir clone has the lowest terpene concentration, the highest aldehyde concentration and the highest 6-Carbon volatile compound concentration that produces a lower total quality value on the palate and is less fruity and citrusy than the Dwari Satsuma sample. The 11/1 İzmir clone also has a lower terpene concentration than the Dwari Satsuma sample and the highest volatile acid value. The 11/1 İzmir clone has a lower total quality value and is less citrusy and aromatic than the Dwari Satsuma sample. Both the 30/İzmir and 11/1 İzmir clones had lower "Dverall liking" values than the Dwari Satsuma sample. Based on these analytical results, it can be concluded that the clones are more efficient in the amount of juice produced, but their flavor qualities seem to be diluted.