# Biochemical Characterization of Some Plum Cultivars Available on the Romanian Market
## 3 Results and Discussion
### Phenolic Compounds  
The total phenolic contents (Figure 3) were highly variable, especially in the plum peel, with the highest amount (109,382 mg/kg DW on average) being found in 'Silvia', while the lowest was in 'Anna Spath' (45,020 mg/kg). In the pulp, the highest amounts were also found in 'Silvia' (82,345 mg/kg), while the lowest was in 'Stanley' (66,231 mg/kg). These  
Figure 1: Percentual water content in plum mesocarp (pulp) and epicarp (peel) in the four studied cultivars (significant differences between cultivars, according to ANOVA, \(p\) < 0.001). Figure 2: Pulp juice pH values in the four studied plum cultivars (significant differences between cultivars, according to ANOVA, \(p\) < 0.001). values equate to 9206-14,163 mg/kg FW in the pulp and 7158-14,770 mg/kg in the peel. For comparison, a study on 13 Chinese _P. salicina_ cultivars found only 1540-2910 mg/kg FW in fruit pulp [29], while 6 American _P. salicina_ and _P. domestica_ cultivars had 1631-3323 FW mg/kg [30]. Figure 3: Concentrations of phenolic compounds (mg/kg DW): (**a**) total phenolic compounds in plum mesocarp (pulp); (**b**) total phenolic compounds in plum epicarp (p peel); (**c**) major phenolic compound classes in plum mesocarp; (**d**) major phenolic compound classes in plum mesocarp; (**f**) minor phenolic compound classes in plum mesocarp in plum epicarp (significant differences between cultivars, according to ANOVA, \(p<0.001\)). The dominant classes of phenolic compounds were flavonoids and hydroxybenzoic acids in all the studied cultivars. Flavonoids were highest in 'Silvia' plums, in both pulp (43,171 mg/kg, representing 52.43% of the total) and peel (51,566 mg/kg--47.14%). Low amounts were found in 'Stanley' (27.07% in the pulp and 33.99% in the peel) and 'Anna Spath' (35.22% and 18.10%, respectively). Among flavonoids, flavanols formed a major fraction of 10.50-31.15% in the fruit pulp, with concentrations above 5000 mg/kg (except for 'Silvia'). The amounts were lower in the fruit epicarp. In 'Anna Spath', they made up 55.61% of all flavonoids but at a low total concentration. Anthocyanins formed minute fractions among flavonoids, with sizeable amounts only in the epicarp, ranging between 438 mg/kg ('Anna Spath') and 1991 mg/kg ('Silvia'). Hydroygenozoic acids had concentrations above 30,000 mg/kg DW and above 40% of the phenolic inventory in the pulp of three cultivars (31,710-33,971 mg/kg, 41.70-48.31%), with the highest amount in 'Angeleno'. 'Silvia' had 25,271 mg/kg (30.69%). Lower amounts were found in the epicarp, 24,432-31,456 mg/kg, with the lowest amount in 'Silvia'. Hydrox-ycinamic acids formed a smaller fraction, with 5449-7162 mg/kg in the pulp (7.38-10.81% of the phenolic inventory; highest in 'Stanley', lowest in 'Angeleno') and 2119-4254 mg/kg in the peel (also highest in 'Stanley' and lowest in 'Angeleno'). The literature shows that not all plum cultivars share the same phenolic profile. A survey of five Turkish cultivars found that flavonoids constituted only 7-17% of the phenolic inventory [31], while phenolic acids (usually dominated by neochlorogenic acid) can make up to 35-63% in the pulp and 23-47% in the peel [32]. Anthocyanins form variable fractions, in some cultivars reaching over 850 mg/kg FW in the pulp and 3440 mg/kg in the peel [33]. Unlike other phenolic compounds, tannins were mostly absent from the fruit pulp, except for 'Anna Spath' (1318 mg/kg). In the epicarp, they ranged from below the detection limit ('Anna Spath') to 24,824 mg/kg ('Silvia'). In other cultivars, tannins were found to form anywhere between 4.6 and 11% of the phenolic inventory in the pulp and 3.7 and 5.6% in the peel [33]. Stilbenes were found in highly variable amounts in the fruit mesoderm, from 2356 mg/kg ('Angeleno') to 6700-6800 mg/kg ('Stanley' and 'Silvia') and 7175 mg/kg ('Anna Spath'). In the peel, the amounts were lower at 1549-2841 mg/kg (highest in Silvia).