## 4 Discussion  
Undoubtedly, there is constant concern about the safety of PIFs regarding _C. sakazakii_[41]. The risk is becoming higher as PIF consumption increases along with the contemporary lifestyles in which infants are fed away from home [42]. For these reasons, a number of international (WHO) and national (FDA and CDC) institutions have released guidelines aimed at reducing the risk of _C. sakazakii_ infections [10; 43]. The recommendations entail utilizing sanitized equipment and heating RIFs to temperatures exceeding 70 \({}^{\circ}\)C [10]. However, these recommendations are frequently neglected, sometimes for practical reasons [18]. \begin{table}
\begin{tabular}{c c c c c c c c c c c c} \hline \hline  & & & & \multicolumn{6}{c}{**Inclusion Time**} \\ \cline{4-13}  & & & & \multicolumn{6}{c}{**12 h**} & & \multicolumn{6}{c}{**24 h**} \\ \cline{4-13}  & & & & \multicolumn{6}{c}{**Concentration (mM)**} & & \multicolumn{6}{c}{**Concentration (mM)**} \\ \cline{4-13}  & & & & **Formic** & **Lactic** & **Acetic**tic & **Sum** & **pH** & **Formic** & **Lactic** & **Acetic** & **Sum** \\ \hline \multirow{4}{*}{\
\begin{tabular}{c} **Construction** \\ \end{tabular} } & \multirow{4}{*}{Mc} & 4.82 & Total \({}^{1}\) & 3.3 & 11.8 & 27.4 & 42.5 & & 3.7 & 15.1 & 40.4 & 59.2 \\  & & 4.82 & (\(\pm\)0.15) & (\(\pm\)0.51) & (\(\pm\)3.05) & (\(\pm\)3.56) & 4.07 & (\(\pm\)0.41) & (\(\pm\)1.52) & (\(\pm\)2.56) & (\(\pm\)4.25) \\  & & & Non-ionic \({}^{2}\) & 0.3 & 1.2 & 12.6 & 14.0 & (\(\pm\)0.02) & 1.2 & 5.8 & 33.4 & 40.4 \\  & & & \(\%\)\({}^{3}\) & 7.8 & 9.9 & 45.9 & 33.0 & & 32.4 & 38.1 & 82.7 & 68.9 \\ \cline{2-13}  & & & 1.3 & 24.9 & 35.7 & 61.9 & & 3.4 & 30.8 & 49.4 & 83.6 \\  & & 4.25 & Total & (\(\pm\)0.11) & (\(\pm\)3.12) & (\(\pm\)1.49) & (\(\pm\)4.50) & 3.65 & (\(\pm\)0.48) & (3+5.7) & (\(\pm\)1.24) & (\(\pm\)3.63) \\  & & & 0.3 & 7.2 & 27.1 & 34.6 & (\(\pm\)0.02) & 1.9 & 10.1 & 45.8 & 57.7 \\  & & & \(\%\) & 24 & 28.9 & 76.0 & 56.0 & & 55.6 & 32.6 & 92.6 & 69.0 \\ \hline \multirow{4}{*}{
\begin{tabular}{c} **Construction** \\ \end{tabular} } & \multirow{4}{*}{Mc} & 5.65 & Total & 1.8 & 15.7 & 30.3 & 47.8 & & 3.3 & 20.8 & 45.6 & 69.7 \\  & & (\(\pm\)0.16) & (\(\pm\)1.30) & (\(\pm\)1.30) & (\(\pm\)1.39) & (\(\pm\)2.21) & 4.60 & (\(\pm\)1.07) & (\(\pm\)0.97) & (\(\pm\)1.24) & (\(\pm\)2.10) \\ \cline{2-13}  & & & 0.02 & 0.25 & 3.38 & 3.65 & (\(\pm\)0.02) & 0.4 & 3.2 & 26.6 & 30.3 \\ \cline{2-13}  & & & \(\%\) & 1.2 & 1.6 & 11.2 & 7.6 & & 12.4 & 15.4 & 58.5 & 43.5 \\ \cline{2-13}  & & & \(\uparrow\) & 19.5 & 39.2 & 59.9 & & 4.6 & 27.7 & 49.9 & 82.2 \\ \cline{2-13}  & & & \(\downarrow\)(\(\pm\)0.08) & Non-ionic & 0.06 & 1.3 & 19.9 & 20.5 & (\(\pm\)0.02) & 1.4 & 9.8 & 40.4 & 51.6 \\  & & & \(\%\) & 5.0 & 6.6 & 48.2 & 33.8 & & 30.0 & 35.5 & 81.0 & 62.8 \\ \hline \hline \end{tabular}  
* Total weak acid concentration (mM), \({}^{2}\) Concentration in non-ionic form (mM), \({}^{3}\) Ratio of weak acid concentration in ionic form/total concentration (\(\%\)).  
\end{table} 
Table 3: Concentration of weak organic acids—formic, lactic, and acetic (\({}^{1}\)total and non-ionic)—produced after 12 and 24 h of incubation at 37 \({}^{\circ}\)C in two infant formulae of different buffering capacities (low/high) inoculated exclusively with _C. sakazakii_ (Mc) and in combination with the probiotic BB-12 (Cc). For instance, it takes more time for the temperature of RIFs to decrease from 70 \({}^{\circ}\)C to 37 \({}^{\circ}\)C, than from 50 \({}^{\circ}\)C to 37 \({}^{\circ}\)C, which is needed for RIF consumption, or, in other cases, rapid cooling is not feasible (e.g., running water). In addition, many infant formulae contain ingredients that are sensitive to temperatures above 70 \({}^{\circ}\)C (e.g., vitamins) or can be denatured (e.g., proteins). Perhaps, for these reasons, several manufacturers of PIFs advise simmering the water and subsequently using it for reconstitution at a temperature of approximately 50 \({}^{\circ}\)C or just using tap water [44, 45].