## 4 Discussion
Data on the long-range molecular order of starch allowed the evaluation of the degree of starch crystallinity. On the other hand, FTIR study of the short-range ordered structure of starch, which reflects the local organization of helices into crystalline arrays, allowed the investigation of modifications in its helical properties. The 1042/1019 ratio was a beneficial tool in assessing changes in the starch structure [29] and reflects the short-range crystallinity that is related to the double-helix packing within the inner granule microstructure [30]. Lastly, DSC analysis enabled the evaluation of the thermal properties of oat flour to reveal the influence of PEF processing on the (1) transition temperatures and (2) enthalpies related to either starch gelatinisation or amylose-lipid complex melting. [PERSON] and [PERSON] [31], [PERSON] et al. [32], [PERSON] et al. [33], and [PERSON] et al. [34] reported an A-type XRD pattern for oat starch, which displayed solid diffraction peaks around 15\({}^{\circ}\) and 23\({}^{\circ}\), a doublet peak at 17\({}^{\circ}\) and 18\({}^{\circ}\), and a small peak at 20\({}^{\circ}\) (20). The comparable XRD pattern exhibited by most segment samples from Control and PEF-treated oat flour (Figure 6) indicates closely packed monoclinic structure of starch that is stable and can inhibit chemical reactions [35]. On the other hand, flour segments from PEF-treated oat flour at 421-438 kJ/ kg (2-C and 4-C) that displayed weakened XRD peaks indicates some degree of transformation in the crystalline region of starch in oat. Derived from the XRD pattern, the percent relative crystallinity was evaluated to determine how PEF treatment affected the crystalline regions of starch in flour segments. The observed decreased on the percent relative crystallinity of segment samples due to PEF treatment of oat flour (i.e., SS1 from 2-C and 4-C, Figure 6) is likely an indication of crystallite disruption or reorientation [36]. On the other hand, higher percent relative crystallinity of starch implies a more stable and crystalline structure. Findings from previous studies on potato and pea starches reported a similar decrease in percent relative crystallinity after PEF-treatment application [9; 37]. It is likely that the compact starch chains in the granules were affected by PEF treatment and led to the alteration of the inner structures of starch, resulting in altered relative crystallinity. In addition, [PERSON] et al. [38] and [PERSON] et al. [39] attributed changes in relative crystallinity of starch, as a result of processing, to several factors including the amount of crystalline regions in the sample, double helices orientation in the crystalline area, and the extent of double helices interaction. The observation of additional peak at 13\({}^{\circ}\) (20) in the XRD pattern of SS1 samples has not been reported in literature to be one of the effects of PEF treatment of starch or starch materials. Nevertheless, previous study on the impact of dual autoclaving-retrogradation processing of oat starch reported a similar 13\({}^{\circ}\) (20) XRD peak observed post processing [40]. New peaks observed in the XRD (e.g., 13\({}^{\circ}\) at 20) patterns typically indicate new crystalline regions were formed. Compared to Control, the significant change in the FTIR ratio (1042/1019) of flour segment samples from PEF-treated oat flour (Table 3) signifies disturbance in double helix packing of the inner starch granule. More specifically, the observed lower 1042/1019 ratio compared to the Control indicates decreased molecular order of the double helix short-range molecules in the granules owing to PEF treatment application (Table 3). This finding verifies previous report on the impact of PEF treatment on the ordered structure of starch [9]. Moreover, the observed prominent shift of major FTIR peak positions (from 1042 to 1050 cm\({}^{-1}\) and 1019 to 1027 cm\({}^{-1}\)) also demonstrates the complexity of the impact of PEF treatment on oat flour.