Deterioration of fried Products and frying Oil

Crisps and frying oils - when exposed to light and/or temperature- oxidize with time, producing a wide series of aldehydes, ketones and acids so that they loose their flavour or become rancid. 

With regard to an optimzed process control, replacement cycles of frying oil can be determined by measuring the grade of rancidity given through a quantification of the  effusion of aldehydes directly sampled from the headspace. Using GC-IMS technology this can either be done by correlating sensory impressions to the fingerprint of the present compounds taken from the headspace, or -same as conventional analytics- quantifying specicific and known marker compounds e.g. hexanal as indicators for rancidity.

G.A.S. instrumentation also enables to detect odour active compounds in crisps or other fried products  through a simple headspace sampling. By that the freshness of a fried product or its storage conditions can easily be monitored.