Analyses of the volatiles of specific flavors revealed that sugar had a high impact on the overall flavor profile (Figure 1
). Fresh, green volatiles (hexyl-acetate and 1-hexanol) were determined in the highest amount in the samples with sucrose and trehalose, 11% higher than in juice without sugar addition. Sweet, floral volatiles (α-ionone, β-ionone, benzyl alcohol, 2-decanon, geranic oxide, β-cyclocitral) were slightly lower in juice with sucrose and maltose addition, while in the samples with trehalose addition a higher amount of those volatiles was determined (8%). In all samples with sugar addition, sweet, fruity volatiles (benzaldehyde, 2-hexenal, 3-methyl-3-buten-1-ol, 2-methyl buthyl butanoate, 3-methyl buthyl butanoate, 2-heptanol, 1-octanol, 1-butanol-3-metyl-acetate) were determined in lower amounts than in juice without sugar addition. Comparing only sugars, samples with trehalose had the highest amount of those compounds. The lowest amount of pungent volatiles (acetic acid, 1-pentanol, 1-penten-3-ol) was determined in juice, and with addition of sugars, their amount increased. On the contrary, ethereal, alcoholic compounds (1-propanol, 2-methyl-1-propanol, 3-methyl-1-butanol, 1-hexanol, 2-methylbutanoate, 2-ethyl hexyl acetate) were determined in the highest amount in juice without sugar addition, and with the addition of sugars their amount decreased. In the case of sweet volatiles (diacetyl, 1-butanol, acetoin, eugenol), there was no difference between juice with the addition of trehalose or maltose and juice, while with the addition of sucrose slightly higher values were obtained.
The results of individual volatile amounts in sour cherry juice with the addition of sugars are presented in Table 1
. Considering the ester group, five esters were identified, namely 1-butanol-3-methyl-acetate, hexyl acetate, 2-methyl butanoate, 2-methylbuthylbutanoate and 3-methylbuthylbutanoate. In all cases, the addition of sugars had an effect on the ester amount. In the case of both acetate esters, the addition of maltose didn’t cause an increase in their amount in comparison to the control sample. Samples with the addition of sucrose or trehalose had higher amounts of both acetate esters, with trehalose having a higher positive effect. Both esters have a sweet, fruity, fresh note. The investigated butanoate esters have a fruity note with a creamy, buttery undernote. The addition of sucrose had no effect on 2-methyl butyl butanoate (1 µg/100 mL), while in samples with maltose or trehalose addition, a higher amount was detected (1.3 µg/100 mL). Similar results were obtained for 3-methylbuthylbutanoate, samples with sucrose and trehalose addition had a higher amount of these esters (0.231 and 0.290 µg/100 mL, respectively) than the control sample and the sample with maltose addition (0.2 µg/100 mL). The addition of sugars had a positive influence on 2-methyl butanoate. The 2-methyl butanoate amount in samples with sugar addition was 1.9 µg/100 mL in comparison to the control sample, 1.616 µg/100 mL. 1-propanol and 2-methyl-1-propanol alcohols that are described by an ethereal, fusel-like note, in the control sample were determined in amounts of 4.365 and 14.335 µg/100 mL, respectively. The addition of sugars affected the amount of both alcohols. The sample with the addition of maltose had the lowest amount of 1-propanol (3.923 µg/100 mL) and the sample with sucrose addition the highest amount (4.472 µg/100 mL). All samples with sugar addition had a lower amount of 2-methyl-1-propanol in comparison to the control sample. Among samples with sugar addition, the sample with the addition of maltose had the lowest amount of this alcohol (9.079 µg/100 mL) and the sample with sucrose addition the highest amount (12.0258 µg/100 mL). Compering butanol derivates, which are described by a sweet, fruity but fusel, alcoholic note, it can be observed that the amount of 1-butanol is the same in all samples (29.5 µg/100 mL), except in the sample with sucrose addition, in which a slightly higher amount (31.331 µg/100 mL) of this alcohol was determined. In the case of the other two determined derivates, all samples with sugar addition had lower amounts of those alcohols in comparison to the control sample. The 1-pentanol (described by a pungent, fermented, fusel like note) was determined in all samples with sugar addition in higher amounts than in the control sample (1.163 µg/100 mL). Samples with maltose or sucrose addition had higher amounts of this alcohol, 1.9 µg/100 mL, than the sample with trehalose, 1.615 µg/100 mL. There was no difference in the amount of 1-penten-3-ol between samples with the addition of sugars in comparison to the control sample. The fruity and alcoholic compound, 1-hexanol, was determined in higher amounts in samples with addition of sucrose or trehalose (6.2 µg/100 mL) than in the control sample and the sample with the addition of maltose (5.7 µg/100 mL). The 2-heptanol, characterized by a fresh, fruity note, was determined in higher amounts in samples with sugar addition. The floral with a sweet, fatty nuance alcohol 1-octanol was determined in the highest amount in the sample with sucrose addition (1.032 µg/100 mL) and in the lowest amount in the sample with maltose addition (0.469 µg/100 mL). Benzyl alcohol and 2-phenyl ethyl alcohol are compounds that are responsible for the characteristic flavor of sour cherries. Benzyl alcohol, which is characterized by floral, rose, phenolic notes, was determined in the control sample in the amount of 3.477 µg/100 mL. The addition of sugars highly affects this volatile compound. In the sample with maltose addition, very low amounts of benzyl alcohol were determined, only 0.0048 µg/100 mL, while in samples with sucrose or trehalose addition, a higher amount (4.1 µg/100 mL) in comparison to the control was determined. Phenyl alcohol, which is also characterized by a floral rose note, was determined in much higher amounts in the control sample, 3.556 µg/100 mL, than in samples with sugar addition. Even if sugars didn’t have positive effect of 2-phenyl ethyl alcohol, the highest amount was determined in samples with sucrose and trehalose, 0.43 µg/100 mL. Benzaldehyde, one of the most characteristic sour cherry volatile compounds, has a strong, sharp, sweet, bitter, almond, cherry-like flavor note. All samples with the addition of sugars had a lower amount of benzaldehyde than the control sample (85.901 µg/100 mL). Comparing the influence of sugars, trehalose had the highest positive influence on these characteristic compounds. Next to benzaldehyde, a very important aldehyde in the characterization of sour cherry aroma, is 2-hexenal, that is described as having a sweet, almond, fruity note. While the addition of maltose had no effect on 2-hexenal (0.45 µg/100 mL), the addition of sucrose and trehalose resulted in higher amounts of this volatile compound (0.51 µg/100 mL). The same effect was observed for β-cyclocitral. In the case of α-ionone and β-ionone (compounds with a woody, sweet, fruity note), it was observed that only the sample with the addition of trehalose had similar content to the control sample, while samples with sucrose or maltose addition had lower amounts of those two volatile compounds, which are also important for the flavor of sour cherries. Diacetyl and acetoin, volatiles described by a sweet, creamy, buttery note, as well as 2-decanon (orange, floral, fatty note) were determined in the same amount in samples with sugars as in the control sample. Sugars had a high impact on geranic oxide, a volatile that is a sweet floral with a woody, cooling nuance. The amount of geranic oxide was around 8 µg/100 mL in samples with trehalose and maltose, 4.969 µg/100 mL in sample with sucrose addition, and only 2.991 µg/100 mL in the control sample. Eugenol (sweet, spicy, woody volatile) was determined in higher amounts in samples with sugar addition (0.6 µg/100 mL) in comparison to the control sample (0.473 µg/100 mL).