*3.2. Physical Characterization* 3.2.1. XRD

Quercetin is a crystalline solid in its pristine form [38], as evident from sharp X-ray diffraction patterns at 8, 10, 12, 13.01, 15, 17 and 27 of diffraction angle (2θ) (Figure 3). The distinct peaks of quercetin with lower intensities were apparent in its mixture of zein, chitosan and pectin. In the diffractograms of qHZ, qHZ-chi and qHZ-chi/pec particles, the crystalline peaks of quercetin disappeared, advocating the transformation from crystalline to an amorous state upon encapsulation in particles [10,39]. Pure zein and chitosan showed mild crystallinity with moderate peaks at 9.56 and 20.24 2θ because of respective α-helixes and crystal lattice structure [40,41]. When zein was structured into HZ, HZ-chi, HZ-chi/pec, qHZ, qHZ-chi and qHZ-chi/pec particles, the diffraction pattern raised from α-helixes in zein and crystal lattice of chitosan became flattened due to interaction between the polymers during the formation of the composite particles [42,43].

**Figure 3.** XRD diffraction patterns of quercetin, mixture (quercetin, zein, chitosan and pectin), zein, chitosan, pectin, HZ, HZ-chi, HZ-chi/pec, qHZ, qHZ-chi, qHZ-chi/pec.
