## 4 Discussion
### Nutritional Properties of Milk Subjected to Thermal Pasteurization Techniques and PEFs
Potential explanations may include protein aggregation and clumping due to denaturation during pasteurization, changes in casein micelle leading to the release of casein molecules, and an increase in the solubility of casein in milk due to thermal pasteurization [31; 32; 33; 34]. Further research is warranted to elucidate the effects of thermal pasteurization on casein content. No significant difference was observed in the DPPH radical scavenging activity across all the samples, which aligns with previous findings [35; 36]. DPPH radical scavenging activity is dependent on the milk composition and the concentration of antioxidants present in milk. Fatty acid content, specifically omega-3, omega-6, and omega-9, was unaffected by thermal pasteurization and PEF methods relative to the control (Figure 7). These fatty acids are relatively stable and resistant to heat [37; 38] Likewise, the cholesterol content was not affected by thermal pasteurization or PEF methods relative to the control. This can be attributed to the relative stability of cholesterol under heat treatment [39; 40]. Gylcomacropeptide (GMP), recognized for its probiotic, anti-inflammatory, immunomodulatory, and antimicrobial effects, as well as appetite regulation, is widely utilized in diverse nutritional and therapeutic applications [41; 42; 43; 44; 45; 46]. In this research, we observed no discernible effects on GMP content in samples treated with thermal pasteurization and PEF relative to the control group. GMP typically exhibits thermal stability under standard thermal pasteurization conditions [57; 58]. Histamine is typically found in trace amounts in raw milk, primarily due to the release from mast cells. Additionally, certain bacteria can produce this biogenic amine. Thermal pasteurization serves to eliminate histamine-producing bacteria, thus preventing an elevation in histamine levels that could potentially trigger intoxication [59; 60; 61; 62; 63]. Our research did not reveal a significant difference in histamine content (Figure 9) between thermally pasteurized, PEF-treated, and control samples. Interestingly, PEF treatment was found to maintain histamine levels on par with those in thermally treated milk. We observed no significant differences in the content of fat-soluble vitamins A, D, and E across all treated samples compared to the control group. These vitamins generally exhibit stability under traditional pasteurization techniques. However, it is important to note that levels of water-soluble vitamins such as B1, B2, B12, and C have been reported to decrease following pasteurization [64; 65; 66]. In our previous article, we proposed the potential adoption of PEF in the manufacture of whey protein powder. To further investigate this, we tested the effects of various pasteurization techniques on raw liquid whey samples (Figure 13), including an additional thermal pasteurization method at 95 \({}^{\circ}\)C for 4 s for comparative purposes. PEF, HTST, LTLT, and MF treatments did not appear to affect \(\beta\)-lactoglobulin content compared to the control. However, heating samples at 95 \({}^{\circ}\)C resulted in a 4.8-fold reduction in \(\beta\)-lactoglobulin content. It has been shown that high temperatures used during spray-drying, a common method in whey protein powder production, reduce whey protein content including \(\beta\)-lactoglobulin concentration and diminishes the quality of whey protein powder by affecting its solubility, emulsification, and foaming properties. The temperatures employed in the spray-drying process of liquid whey often exceed those of LTLT, HTST and MF pasteurization, ranging from air inlet temperature of 150 \({}^{\circ}\)C to 260 \({}^{\circ}\)C and air outlet temperature of 60 \({}^{\circ}\)C to 120 \({}^{\circ}\)C [67; 68; 69; 70].