# The Effect of Apple Juice Concentration on Cider Fermentation and Properties of the Final Product
## 3 Results and Discussion
### Fermentation Kinetics  
The fermentation kinetics results of ciders prepared from either fresh juice or juice concentrate, fermented with different yeast at two different temperatures with or without a nutrient are provided in Figure 1. In all samples, fermentations were successfully completed with no signs of sluggish fermentation.  
\begin{table}
\begin{tabular}{c c c} \hline \hline
**FAA, mg L\({}^{-1}\)** & **Juice, 9.8\% Brix** & **Concentrate, 10\% Brix** \\ \hline His & \(1.71\pm 0.32\) & \(2.27\pm 0.44\) \\ Asn & \(269.60\pm 24.48\) & \(315.03\pm 32.70\) \\ Ser & \(6.28\pm 0.93\) & \(9.21\pm 0.82\) \\ Gln & \(3.26\pm 0.60\) & \(2.87\pm 0.26\) \\ Arg & \(21.68\pm 1.10\) & \(19.36\pm 3.63\) \\ Gly & \(0.32\pm 0.04\) & \(1.19\pm 0.21\) \\ Asp & \(38.10\pm 5.26\) & \(44.42\pm 4.46\) \\ Glu & \(32.43\pm 3.54\) & \(38.15\pm 3.67\) \\ Thr & \(2.75\pm 0.45\) & \(3.62\pm 0.33\) \\ Ala & \(8.85\pm 1.56\) & \(10.91\pm 1.01\) \\ Pro & \(2.32\pm 0.37\) & \(3.22\pm 0.33\) \\ Orn & \(0.27\pm 0.02\) & \(0.51\pm 0.10\) \\ Cys-cys & \(0.30\pm 0.03\) & \(0.34\pm 0.03\) \\ Lys & \(0.82\pm 0.09\) & \(1.93\pm 0.08\) \\ Tyr & \(0.88\pm 0.06\) & \(1.04\pm 0.22\) \\ Met & \(1.06\pm 0.16\) & \(1.27\pm 0.12\) \\ Val & \(3.93\pm 0.73\) & \(4.41\pm 0.46\) \\ Ile & \(2.34\pm 0.45\) & \(2.90\pm 0.33\) \\ Leu & \(1.18\pm 0.23\) & \(3.21\pm 0.39\) \\ Phe & \(1.97\pm 0.16\) & \(1.98\pm 0.21\) \\ Trp & \(0.57\pm 0.10\) & \(0.41\pm 0.03\) \\ FAN, mg L\({}^{-1}\) & \(76.13\pm 7.29\) & \(87.91\pm 9.62\) \\ + DAP YAN, mg L\({}^{-1}\) & \(95.03\pm 7.29\)1  & \(106.81\pm 9.62\) \\ + Fermid O YAN, mg L\({}^{-1}\) & \(93.33\pm 7.29\)2  & \(105.11\pm 9.62\) \\ \hline \hline \end{tabular}
\end{table}
Table 1: Free amino acid (FAA) composition, free amino nitrogen (FAN) content before and yeast assimilable nitrogen (YAN) content after supplementation. Standard deviation is shown (\(n=3\)).  
Figure 1: Fermentation kinetics of cider samples prepared from fresh juice or juice concentrate with different yeasts (Y1-Y6) at 18 or 30 \({}^{\circ}\)C. The samples done with the concentrate are represented by a green line and with the juice by an orange line. The samples fermented at 18 \({}^{\circ}\)C are represented by a dashed line of appropriate color; by a solid line at 30 \({}^{\circ}\)C.  
Expectedly, some differences between strains could be observed while the temperature was the main factor affecting yeast fermentative activity. The yeast fermented at least two times faster at 30 \({}^{\circ}\)C. No particular difference in fermentative activity can be noted between the juice and reconstituted concentrate at 18 \({}^{\circ}\)C. However, at 30 \({}^{\circ}\)C, the fermentation activity on reconstituted concentrate was slightly inferior to the juice. A loss of certain nutrients during the concentration process might have affected the ability of yeast to cope with higher temperatures but the change is not drastic enough to significantly impact the effectiveness of the process. In this case, the supplementation fills the necessary nutritional gap enough to make the yeast perform better.