## 3 Results and Discussion
### Waste Chemical Characterization and Fermentation Mash Preparation  
The chemical characterization of pear pomace and RCW used in this study are reported in Table 4. \begin{table}
\begin{tabular}{c c c} \hline \hline
**Parameter** & **Pear Pomace (g/L)** & **RCW (g/L)** \\ \hline Dry matter & - & 93.89 \(\pm\) 0.85 (\% \(w/v\)) \\ TPS \({}^{\star}\) & 85.36 \(\pm\) 2.78 & 47.50 \(\pm\) 1.22 \\ Glucose & 18.68 \(\pm\) 1.15 & - \\ Fructose & 64.43 \(\pm\) 1.51 & - \\ Lactose & - & 47.50 \(\pm\) 1.22 \\ Sorbitol & 2.25 \(\pm\) 0.10 & - \\ N & 0.496 \(\pm\) 0.200 & 0.976 \(\pm\) 0.19 \\ Protein & 3.1 & 6.1 \\ Na & 0.075 \(\pm\) 0.020 (mg/L) & 0.166 \(\pm\) 0.088 (mg/L) \\ K & 8.130 \(\pm\) 0.700 (mg/L) & 0.858 \(\pm\) 0.099 (mg/L) \\ Ca & 0.323 \(\pm\) 0.092 (mg/L) & 0.040 \(\pm\) 0.011 (mg/L) \\ Fe & \(\sim\)0.001 \\ Mg & 0.370 \(\pm\) 0.017 (mg/L) & 0.160 \(\pm\) 0.022 (mg/L) \\ pH & 4.08 \(\pm\) 0.02 & 5.10 \(\pm\) 0.02 \\ \hline \end{tabular} \({}^{\star}\)TPS: Total fermentable sugars.  
\end{table} 
Table 4: Chemical composition of pear pomace and ricotta cheese whey (RCW). Figure 1: Concentration of L-lactic, D-lactic and the sum of D + L-lactic for _L. casei_ (**a**) and _L. fractiminis_ (**b**) with different oxygen supply (\(p\) < 0.05). \begin{table}
\begin{tabular}{c c c c c c c c c c} \hline \hline  & \multicolumn{4}{c}{**Aerobic**} & \multicolumn{4}{c}{**Microaerophillic**} & \multicolumn{2}{c}{**Anaerobic**} \\ \cline{2-10}
**Strain** & **d-LA** & **l-LA** & **l + d-LA** & **d-LA** & **l-LA** & **l + d-LA** & **d-LA** & **l-LA** & **l + d-LA** \\  & **(g/L)** & **(g/L)** & **(g/L)** & **(g/L)** & **(g/L)** & **(g/L)** & **(g/L)** & **(g/L)** & **(g/L)** \\ \hline _L. alimentarius_ & 0.00 & 0.00 & 0.00 & 0.00 & 0.00 & 0.00 & 0.00 & 10.99 & 10.99 \\ _L. bjferntants_ & 0.00 & 2.84 & 2.84 & 0.00 & 1.68 & 1.68 & 3.91 & 1.55 & 5.46 \\ _L. casei_ & **2.92** & **12.89** & **15.81** & **2.15** & **13.74** & **15.89** & **2.02** & **18.00** & **19.50** \\ _L. collobiosus_ & 0.00 & 0.71 & 0.71 & 0.00 & 4.07 & 4.07 & 3.65 & 4.85 & 8.50 \\ _L. collinides_ & 0.00 & 1.75 & 1.75 & 0.00 & 1.68 & 1.68 & 5.26 & 2.39 & 7.65 \\ _L. fractiminis_ & **3.52** & **10.66** & **14.18** & **0.00** & **15.71** & **15.71** & **5.32** & **13.05** & **18.37** \\ _L. curvtatus_ & 0.00 & 0.00 & 0.00 & 0.00 & 0.00 & 0.00 & 0.00 & 0.00 & 0.00 \\ _L. fractosus_ & 0.00 & 0.00 & 0.00 & 0.00 & 0.00 & 0.00 & 1.03 & 0.00 & 1.03 \\ _W. halotototrans_ & 4.77 & 1.84 & 6.62 & 4.33 & 3.75 & 8.07 & 0.00 & 1.75 & 1.75 \\ _L. hilgardii_ & 0.00 & 1.94 & 1.94 & 0.00 & 2.33 & 2.33 & 2.82 & 1.16 & 3.98 \\ _L. kefri_ & 0.00 & 2.00 & 2.00 & 0.50 & 1.50 & 2.00 & 0.01 & 0.00 & 0.01 \\ _L. jensenii_ & 5.19 & 0.00 & 5.19 & 0.49 & 1.51 & 2.00 & 5.58 & 0.00 & 5.58 \\ _L. fermentutum 20049_ & 0.00 & 2.97 & 2.97 & 1.54 & 0.84 & 2.38 & 0.00 & 0.00 & 0.00 \\ _L. fermentutum 20052_ & 1.09 & 2.72 & 3.80 & 1.79 & 3.81 & 5.61 & 1.41 & 2.26 & 3.67 \\ _W. [PERSON]_ & 2.34 & 0.00 & 2.34 & 1.57 & 0.39 & 1.96 & 7.81 & 1.23 & 9.04 \\ _L. reuteri 20015_ & 0.00 & 0.00 & 0.00 & 0.00 & 0.00 & 0.00 & 0.00 & 0.00 \\ _L. reuteri 20016_ & 2.69 & 3.75 & 6.44 & 1.86 & 0.84 & 2.70 & 1.54 & 1.42 & 2.96 \\ _L. salivitrius_ & 0.00 & 0.00 & 0.00 & 0.00 & 0.00 & 0.00 & 0.019 & 0.00 \\ _[PERSON]. [PERSON]_ & 0.00 & 0.00 & 0.00 & 0.00 & 0.00 & 0.00 & 0.00 & 0.00 \\ \hline \hline \end{tabular} \({}^{\star}\)TPS: Total fermentable sugars.  
\end{table} 
Table 3: Total lactic acid (l + d-LA), D-lactic acid (D-LA) and l-lactic acid (l-LA) concentrations obtained by the screening of 19 LAB strains in different oxygen supply conditions. Pear pomace puree used as raw material in these experiments was too dense to be fermented without dilution. The possibility of using water was taken into account only in the first lab test, but then discarded when the scale up to the fermenter was set up for the obvious impact of using fresh tap water on the overall environmental and economic balance of the process.