## 4 Discussion
Secondly, the wide range of particle sizes (5-552 \(\upmu\)m) exhibited by different segments investigated demonstrate the range of particle size heterogeneity, particularly within a treatment (e.g., 4-C-SS1 vs. SS2 vs. SS3, Table 2). The varying extent of change in the particle size (two- to eight- fold increase) of flour components that was observed in various flour segments also stresses the uneven PEF treatment effect on oat flour components. In addition, the unimodal and multimodal size distribution displayed by each flour segment sample (Figure 3), which indicates clusters of varying particle sizes, is a demonstration of the asymmetrical impact of PEF treatment on a heterogeneous material. Lastly, although the aforementioned cases highlight the variation of properties within a treatment, it cannot be denied that alterations exhibited by certain flour segments would impart a major impact on the overall property of the entire sample (e.g., starch susceptibility to digestive enzymes). This is most substantially observed in PEF-treated oat flour samples at 421-438 kJ/kg (2-C and 4-C), which was found to be the most susceptible to digestive enzymes amongst the samples analysed (Figure 2). The SS3 samples from 2-C and 4-C did not manifest significant difference from the corresponding SS3 segment of the Control in terms of granule morphology, particle size, XRD pattern, relative crystallinity, FTIR ratio, and thermal enthalpies. However, the SS1 segments from the same samples (2-C and 4-C) displayed the greatest degree of modification in the overall properties evaluated. Findings from this study have consistently showed that varying degrees of modification in the particle size and morphological characteristics observed in flour segments obtained from PEF-treated oat flour is indicative of PEF influence. Firstly, the bigger particle size exhibited by segment samples obtained from PEF treatment of oat flour at 421-438 kJ/kg (Table 2) can be attributed to particle aggregation based on the small shoulders observed on the side of well-defined peaks (Figure 3). This finding was validated by the observed agglomeration of starch granules that was captured in SEM micrographs (Figure 4). [PERSON] et al. [26] previously reported that starch granules tend to aggregate in the presence of gelatinised starch, which acted as an \"adhesive\" to cluster starch granules and hold the aggregates together. Secondly, the observed loss of starch granule integrity and starch deformation for samples that was processed at 421-438 kJ/kg implies that starch granules in oats can be very sensitive to structural modification under the influence of high specific energy input application. It is also likely that the collective impact of PEF treatment and the concomitant temperature increase (up to 33 \({}^{\circ}\)C temperature change) during processing rendered starch granules to be more vulnerable to alteration. Lastly, data on the particle size distribution of segment samples revealed that the size of the granule cannot be used to generalise denseness of oat flour components (e.g., big particles or starch aggregates tend to settle at the bottom). This is particularly applicable for segment samples collected after oat flour PEF treatment at 421-438 kJ/kg (2-C and 4-C). With the biggest component particle sizes manifested by samples collected from the top layer (SS1) of 2-C and 4-C, PEF treatment of oat flour at 421-438 kJ/kg would have caused alteration in the structural packing within the starch granule that resulted in larger but less dense segments. Investigation of various flour segments, through the collective XRD, FTIR, and DSC analyses, permitted the characterisation of ordered structure for starch. The data gathered provided a comprehensive overview on how starch would interact with other molecules, such as water. XRD is the only analytical technique that may be used to evaluate and quantify the long-range order in starch [27] based on the loss of intensity in crystalline peaks after atoms deviate from their ideal positions [28].