Analysis of Early Lipid Oxidation in Smoked, Comminuted Pork or Poultry Sausages with Spices

Summary

Analytical methods that can detect low levels of lipid oxidation in food are valuable tools in research, product development and quality control. Dynamic headspace/GC-MS, front-face fluorescence and a gas-sensor array technique (an electronic nose) have previously been used to detect lipid oxidation in pork back fat or mechanically recovered poultry meat earlier than or at the same time as a sensory panel. In the present study, smoked, comminuted sausages with spices were made of pork or poultry meatand stored in vacuum or air at –20 °C for 11 months. The samples were analyzed with the methods listed above to explore their applicability in more complicated products. The results showed that sensory analysis of these complex matrixes was not straightforward. The sensory panel seemed to reach an upper threshold for differentiating between rancidity and other odor and flavor notes from e.g. spices or smoke in the pork sausages stored in air. The poultry sausages contained less total fat and less PUFA and showed less development of rancid odor and flavor during the storage time. For complex matrixes like this, containing a large array of different types of components, a highly specific method like dynamic headspace/GC-MS might be the best option for detection of small oxidative changes. Hexanal and 1-penten-3-ol analyzed with this technique was found to be good markers for early lipid oxidation of n-6 and n-3 fatty acids, respectively. 2-Furancarboxaldehyde decreased in both types of sausages andmight be associated with loss of acidic or meat flavor. Front-face fluorescence yielded spectra that indicated increasing levels of lipid oxidation in pork sausages stored in air, but the data were difficult to interpret. Degradation of e.g. Maillard-type components during storage might have led to decreasing fluorescence in poultry sausages stored in air. The gas-sensor array sensors could not separate the signals from lipid oxidation products and spice- and smoke-components.