# Aroma Profile of Monovarietal _Pet-Nat_ Ciders: The Role of Croatian Traditional Apple Varieties
## 3 Results and Discussion
### Pet-Nat Ciders Basic Analysis  
The final product characteristics are given in Tables 2 and 3. The basic parameters on _Pet-Nat_ ciders showed the average alcohol content of 7.13% (_v/v_) with no significant differences between the varieties (Table 2). An overall increase in pH value was observed (0.1-0.5), with significant differences between samples, the highest being observed in 'Bozicnica'. The highest drop in total acidity, accordingly, was noted in 'Bozicnica', while in 'Crvenka' cider, an increase, in comparison to juice, was observed. The fluctuation in the metabolism of acids is influenced by many factors, such as temperature, pH, and oxygenation, the microorganisms involved, and the chemical composition of the medium (nitrogen compounds and SO\({}_{2}\)) [45]. The content of polyphenols affects the quality of ciders through organoleptic characteristics such as color, bittermess, astringency and aroma [7] and their fluctuations can be affected by the adsorption and desorption ability of yeast [45]. The total phenols (TP) content (Table 3) of _Pet-Nat_ ciders was within the range 416-539 mg:L\({}^{-1}\), with significant differences between the varieties. The TP content was thus lower than the range in apple wines of 734-2463 [46] and 792-3399 mg:L\({}^{-1}\) depending on the variety. According to other authors, traditional varieties have the same groups of polyphenols as commercial but in higher or similar amounts [12; 47; 48]. The investigation of twenty-five traditional apple varieties, in higher or similar polyphenol concentration in comparison to a commercial variety 'Idared', mostly grown in Croatia [12]. In the available literature, one study reported 660 mg:L\({}^{-1}\) of TP in sparkling cider, which decreased after the secondary fermentation [49] due to the adsorption ability of yeast. The highest concentration of TP was determined in 'Bobovac' sparkling cider (Table 2), although 'Bozicnica' and 'Crvenka' apples were determined as richer in polyphenols according to [PERSON] et al. (2020) [12]. The TP concentration of 721.6 mg:L\({}^{-1}\) in cider from 'Fuji' apples reported by [PERSON] et al. (2014) [45] was 1-3 times higher than in ciders obtained from 'Sampion', 'Idared' and 'Gloster' apples varieties. Since the higher concentration of certain phenolic compounds are usually responsible for higher color intensity and browning of wine through enzymatic or non-enzymatic pathways [5], the color intensity (CI) of analyzed sparkling ciders was, as expected, accordant with TP amount (Table 3) and visual evaluation of wines during sensory evaluation. \begin{table}
\begin{tabular}{c c c c} \hline \hline
**Parameter** & **’Bozicnica’** & **’Bobovac’** & **’Crvenka’** \\ \hline Density (Oe\({}^{\circ}\)) & 56 \(\pm\) 2 & 57 \(\pm\) 1 & 55 \(\pm\) 1 \\ pH & 3.38 \(\pm\) 0.3 a & 3.33 \(\pm\) 0.2 b & 3.24 \(\pm\) 0.3 c \\ Total acidity, TA (g:L\({}^{-1}\)) * & 5.6 \(\pm\) 0.05 c & 6.1 \(\pm\) 0.1 b & 8.0 \(\pm\) 0.05 a \\ Malic acid (g:L\({}^{-1}\)) & 4.96 \(\pm\) 0.05 c & 5.18 \(\pm\) 0.03 b & 6.41 \(\pm\) 0.02 a \\ FAN (mg:L\({}^{-1}\)) & 16.7 \(\pm\) 0.09 a & 12.7 \(\pm\) 0.08 c & 14.72 \(\pm\) 0.1 b \\ NHt\({}^{\star}\) (mg:L\({}^{-1}\)) & 97.2 \(\pm\) 1.7 b & 94.6 \(\pm\) 1.6 c & 124 \(\pm\) 1.9 a \\ YAN (mg:L\({}^{-1}\)) & 113.9 \(\pm\) 1.0 b & 107.3 \(\pm\) 1.5 c & 138.7 \(\pm\) 1.1 a \\ \hline \hline \end{tabular}  
* as malic acid; results are means of three measurements; means with different letters differ significantly among varieties (\(p\leq 0.05\)) based on the [PERSON]’s multiple rang test.  
\end{table} 
Table 1: Quality parameters of apple juices before fermentation.