Frying produces complex changes in the chemistry of both the food and the frying medium. Thermal oxidation, polymerization, hydrolysis, degradation, and Maillard reactions all produce several classes of new compounds. These compounds are analysed via a number of analytical methods, either qualitatively or quantitatively. The aim of analysis is to obtain composition data concerning the new compounds formed, in order to elucidate any nutritional changes they may have caused. This chapter, therefore, looks only at analytical methods related to composition studies, mostly chromatographic studies; spectroscopic studies are beyond its scope. The limitations of each method may warrant the development of new or improved methodology. The following limitations are considered while aiming to develop a new analytical method:
- The lower limit of detection or quantification.
- The high cost of the chemical or equipment.
- The reliability or reproducibility of the method.
- Low accuracy or validity.
- Low reproducibility.
- The complex nature of the frying medium and of the food.
- Different target analytes.
- The nature of the separation mode.
- The nature of the analytes.
Several review papers have aimed to collate the knowledge relevant to each topic or component of food frying. For example, Paul and Mittal (1997) reviewed the various regulations on the use of degraded oil or fats in the deep frying of foods; Hindra and Baik (2006) reviewed the kinetics of changes in the quality ...