# Chemical Characterization of Cider Produced in Hardanger--From Juice to Finished Cider
## 3 Results and Discussion
### Chemical Composition of Apple Jices and End Fermented Cider of Different Apple Fruit Cultivars
#### 3.1.2 Total Phenols and Individual Polypphenols
The total polyphenols measured using the _Folin-Ciocalteu_ method are at a higher level than the total polyphenols measured by HPLC. An overestimation of the polyphenol concentration when using the _Folin-Ciocalteu_ method is well known, as reagents react with other reducing compounds, such as reducing sugars, sulfur dioxides, and proteins [31]. In our samples, there were sugars, which are even more abundant in the juice than in the finished cider. The main individual polyphenols in the juices and ciders were chlorogenic acid (ranging from 22.3 to 214 mg L\({}^{-1}\) in juices and from 10 to 231 mg L\({}^{-1}\) in the ciders), followed by catechin, epicatechin, and dimeric procyanidins B1 and B2 (Table 3). This is in accordance with the findings of [PERSON] et al., [PERSON] et al., and [PERSON] et al. [16; 32; 1] who found flavanols (catechin, epicatechin, and procyanidins), hydroxycinnamic acids (chlorogenic acids, 5-caffeoylquinic acid and 4-\(p\)-coumaroylquinic acid), dihydrohalcones (phloridin, phloretin glucoside, and xyloglucoside), flavonoids (quercetin glucosides), and anthocyanin (cyanidin galactoside) to be the main polyphenols in apples. The concentrations of chlorogenic acid in our ciders were in similar concentration ranges as those in a Croatian study for Idared and Cripps Pink apple ciders [16]. The average level of chlorogenic acid in 'Aroma' and 'Discovery' shows a tendency to decrease from juice to cider, most likely due to oxidation or because of hydrolysis into caffe acid and quinic acid. An increasing trend (on average) was observed for the other two cultivars, 'Gravenstein' and 'Summerred'. This variation appears to be cultivar- and yeast-dependent [16; 1]. Changes in caffe acid have been observed in all ciders (compared to juices) and are in agreement with the literature reporting on increasing trends of caffe acids during the fermentation of apple juice [1; 27], assumably due to the hydrolysis process of chlorogenic acid, as already mentioned before. With respect to juices from the same cultivar, the most obvious increase was observed in the 'Discovery' ciders whereas for the other samples, it was not as obvious. Catechin and epicatechin and their dimeric (B and A types) and trimeric derivatives (C type) contribute to the bitter taste of alcoholic beverages like wine [17; 23]. In wines, procyanidins with longer chains of epicatechin, catechin, and their derivatives (up to four subunits) are known to be responsible for a bitter taste, while high molecular tannins (procyanidins with \(>\)7 subunits of flavan-3-ols) are responsible for astringency. The main proanthocyanidin was B2, ranging in average from 2.2 mg L\({}^{-1}\) in 'Summerred' ciders up to 24.9 mg L\({}^{-1}\) in 'Gravenstein' ciders; similar concentrations ranges (slightly lower) were observed for B1 proanthocyanin (2.8 mg L\({}^{-1}\) in 'Summerred' and 21.7 mg L\({}^{-1}\) in 'Discovery' ciders.). The level of catechin seems to be quite stable in all cultivars during fermentation, except for 'Gravenstein', where an average increase was observed from the initial 7.9 to the