The pharmaceutical industry requires narrow variability in the dissolution rate of hard gelatin capsules. To test this property, gelatin is aged in high temperature and humidity conditions to mimic gelatin shelf-life. These conditions induce cross-link formation in gelatin chains and change the properties of the capsule. Gelatin is produced worldwide in various environmental conditions. This study set out to evaluate the impact of geographic production origin on gelatin composition, before and after aging treatment, and on its dissolution properties. Non-aged and aged pig skin gelatins from three different production plants (A, B and C) were analyzed in raw granules and in powder by near infrared and fluorescence spectroscopy to identify the mechanisms of cross-link formation during aging. Gelatin composition (lipids, dityrosine, 3,4 dihydroxyphenylalanine (DOPA)) and oxidation level, before and after aging, varied according to production origin. The gelatin from C showed no variability in dissolution rate, while gelatins from A and B dissolved more slowly after aging. Near infrared spectroscopy results suggest that water was more strongly bound to the gelatin chains in the gelatins that yielded non-compliant dissolution test results. Non-compliant gelatin exhibited more CH2, usually assigned to lipids, and more aldehydes. Even before aging we found that non-compliant gelatins tended to fluoresce more at 344 nm under 280 nm excitation. These results open new perspectives for designing tools to predict the dissolution quality of freshly produced gelatins.