A tamper-proof barcoded quality indicator operative to provide a machine-readable indication of exceedance of time and temperature thresholds following actuation thereof, including a first barcode including a first colorable area and being machine-readable before exceedance of the time and temperature thresholds, a second barcode including a second colorable area and not being machine-readable before exceedance of the time and temperature thresholds, a coloring agent located at a first location on the indicator, a coloring agent pathway operative to allow the coloring agent to move, at a rate which is at least partially a function of time, from the first location to the first and second colorable areas simultaneously for simultaneous coloring thereof upon exceedance of the time and temperature thresholds, thereby causing the first barcode to become unreadable and at the same time causing the second barcode to become machine-readable, and a tamper-proof actuator element operative to actuate the indicator.