A pressure sensor and its use for visually determining whether a preselected pressure threshold has been achieved, for example during high pressure processing treatment of a foodstuff. The pressure sensor includes a contained color-changing system having a dye, a developer, and a solvent; upon achievement of the preselected pressure threshold, the dye and the developer interact, resulting in a visible color change. Further, the visible color change can be retained upon a decrease in pressure and upon an increase in temperature, thereby effectively recording the achievement of the preselected pressure threshold during the high pressure processing treatment.