A non-intrusive method for determining an indication of wholesomeness of an unopened item of packaged aliment comprising the steps of illuminating an unopened item of packaged aliment with electromagnetic energy at a plurality of different wavelengths through a suitably transparent region of the packaging so as to interact with the packaged aliment; obtaining spectral information regarding the interaction of the plurality of different wavelengths with the packaged aliment as subsequent spectral information; interrogating the packaging to access original spectral information regarding a previous interaction of the plurality of wavelengths with the same unopened item of packaged aliment and associated with the packaging; comparing some or all of the subsequent spectral information with some or all of the original spectral information to obtain a measure of their spectral deviation; and determining an indication of wholesomeness of the unopened item of packaged aliment in dependence of the obtained measure of spectral deviation.