# Development and Analysis of an Intensified Batch-Fed Wine Fermentation Process
## 3 Results
### Pilot Fermentations  
The intensified fermentations saw a substantial impacts versus the control, with substantial fermentation velocity, cell density, and overall cycle time improvements, as seen in Table 2 and Figure 2. The semi-batch fermentation had the highest specific growth rate, an expected result as it had a low initial inoculum compared to the recycle semi-batch, but much higher available YAN versus the control. The recycle-semi-batch had the fastest peak fermentation rate and reached 0 Brix before the other fermentations. The recycle semi-batch-fermentation had the lowest residual sugar at the end of fermentation, at half the value of the semi-batch fermentation. Interestingly, the control fermentation had an order of magnitude higher residual sugars at the end of fermentation. The control sample did have slightly lower overall YAN at the end of fermentation.  
Figure 1: Consumption of YAN as a function of fermentation progression, current optical density, and current YAN. Data points captured 2x/day over the course of flask fermentations.  
Cell density and cell viability varied between conditions in interested ways. Both the semi-batch and recycle-semi-batch fermentation had more than double the end point dry cell weight of the control fermentation. Interestingly, the semi-batch fermentation had the healthiest cells at the end of fermentation, with 76% cell viability, as well as the highest cell number. The recycle-semi-batch had the lowest viability, an expected result given the additional age of the culture due to recycle.  
All fermentations measured <30 mg/L residual YAN at the end of fermentation, and all fermentations were measured below ethyl carbamate detection threshold (>3 micrograms/mL) via HPLC MS/MS (QQQ) from ETS Labs.  
\begin{table}
\begin{tabular}{c c c c c c c c c} \hline \hline
**Trial** & \(\mu\_\_\_\_\)**max, 1/h** & \begin{tabular}{c} **Max \({}^{\circ}\)Brix** \\ **Rate, \({}^{\circ}\)B/h** \\ \end{tabular} & \begin{tabular}{c} **Time to** \\ **0 \({}^{\circ}\)B, h** \\ \end{tabular} & \begin{tabular}{c} **Residual** \\ **Sugars at** \\ **End, g/L** \\ \end{tabular} & \begin{tabular}{c} **YAN at** \\ **End (mg/L)** \\ \end{tabular} & \begin{tabular}{c} **End Cell** \\ **Number,** \\ **cell/mL** \\ \end{tabular} & \
\begin{tabular}{c} **End Cell** \\ **Viability,** \\ \end{tabular} &
\begin{tabular}{c} **Final Dry** \\ **Cell** \\ **Weight g/L** \\ \end{tabular} \\ \hline Control & 0.13 & 0.21 & 249.3 & 0.86 & 12.5 & \(7.14\times 10^{7}\) & 60\% & 2.31 \\ \hline Semi-Batch & 0.26 & 0.35 & 142.8 & 0.045 & 28 & \(1.30\times 10^{8}\) & 76\% & 4.86 \\ \hline Recycle Semi-Batch & 0.09 & 0.38 & 99.2 & 0.02 & 26.5 & \(1.19\times 10^{8}\) & 53\% & 5.18 \\ \hline \hline \end{tabular}
\end{table}
Table 2: Pilot fermentation kinetics.  
Figure 2: Fermentation curves showing Brix and Optical Density of the control, Semi-Batch (S-B), and Recycle-Semi-Batch (Recycle S-B) fermentations. The 95% confidence intervals are shown. The control slowly reaches a lower peak biomass compared to the intensified processes. The recycle-semi-batch starts at a much higher initial optical density due to the recycled inoculum. Substantial fermentation cycle time improvements are gained via the intensified processes.