## 4 Discussion  
### Nutritional Properties of Milk Subjected to Thermal Pasteurization Techniques and PEFs  
In this investigation, unlike our previous study [27], we have placed a greater emphasis on assessing the nutritional properties of milk subjected to thermal pasteurization techniques compared to PEF treatment. UHT pasteurization, however, was not included within the scope of this research, as its impact on whey protein content was discussed previously [27]. We applied HT pasteurization at 95 \({}^{\circ}\)C for 4 s on liquid whey samples for comparative purposes. In contrast to our initial hypotheses, we discerned no substantial difference in the amino acid content amongst samples subjected to microfiltration (MF), low-temperature, long-time (LTLT), high-temperature, short-time (HTST), and pulsed electric field (PEF) treatments (Figure 2). This observation is congruent with extant literature that posits mild heat treatment does not significantly modify the amino acid content of milk in relation to raw milk [28], demonstrating the parity of PEF treatment with traditional thermal pasteurization techniques. Nevertheless, it bears mentioning that ultrahigh-temperature (UHT) pasteurization has been documented to markedly impact the amino acid content, with an average decrement of 34% noted in the levels of cysteine, cystine, and methionine in skim milk samples treated using the UHT steam injection technique [29]. \begin{table}
\begin{tabular}{l l c c c c c c} \hline \hline \multirow{2}{*}{**No.**} & **Milk Samples** & \multicolumn{3}{c}{**Total Number of Bacteria**} & \multirow{2}{*}{**Coliform Bacteria, CFU/mL**} & \multicolumn{3}{c}{**Mesophilic Lactic Acid**} \\  & & **Found in Samples, CFU/mL** & & & **Bacteria CFU/mL** \\ \cline{3-8}  & **Mean** & **SD** & **Mean** & **SD** & **Mean** & **SD** \\ \hline
1. & RM & 9 \(\times\) 10\({}^{4}\) a & 1.5 \(\times\) 10\({}^{3}\) & 1.6 \(\times\) 10\({}^{2}\) a & 21 & - & - \\
2. & RWC & 8.3 \(\times\) 10\({}^{3}\) b & 3.6 \(\times\) 10\({}^{2}\) & 12 b & 2 & 5.5 \(\times\) 10\({}^{3}\) a & 1.5 \(\times\) 10\({}^{2}\) \\
3. & PEF & 6.2 \(\times\) 10\({}^{3}\) c & 1 \(\times\) 10\({}^{2}\) & \(<\)4 & - & 1.6 \(\times\) 10\({}^{2}\) b & 17 \\
4. & HT & \(<\)1 & - & \(<\)1 & - & \(<\)1 & - \\
5. & HTST & 2.4 \(\times\) 10\({}^{2}\) d & 34 & \(<\)1 & - & \(<\)1 & - \\
6. & LTLT & 7 \(\times\) 10\({}^{2}\) d & 92 & \(<\)1 & - & \(<\)1 & - \\
7. & MF & 36 d & 8 & \(<\)1 & - & \(<\)1 & - \\ \hline \hline \end{tabular}
\end{table} 
Table 1: Comparison of colony forming units (CFUs) of total bacteria and mesophilic lactic acid bacteria in samples subjected to different pasteurization techniques. \(\beta\)-Lactoglobulin content in milk samples remained consistent across all thermal pasteurization techniques and PEF treatment relative to the control. Interestingly, a 75% reduction in \(\beta\)-lactoglobulin content was observed in our previous study, where samples were treated with an industrial-scale LTLT pasteurization line [27]. This variance may be attributed to the multistage processing of raw milk, including creaming, pasteurization and homogenization [30], which were not accounted for in the current study. We caution against directly comparing the results from our previous research [27], as all thermal pasteurization, apart from PEF treatment, was conducted using industrial-scale pasteurization lines. The thermal pasteurization in this research was performed on whole milk according to industry-standard heat treatment procedures. An intriguing observation from our study was the increased \(\beta\)-casein and \(\kappa\)-casein content in samples treated with LTLT pasteurization relative to PEFs and control (Figure 4). The level of casein content increased across all samples subjected to thermal pasteurization. However, statistical significance was only observed in samples treated with LTLT. The mechanisms underlying the thermal pasteurization-induced increase in casein content are not fully understood.