GC/MS analysis of volatile aroma components in butter during storage in different catering packaging

Effect of storage times, temperature and packaging materials on the formation of volatile compounds in butter was investigated. Butter was stored for 14 weeks at -18, 4 and 20°C, respectively, and analyzed every second week. By means of a dynamic head-space GC/MS-method using Tenax traps the butter was analyzed for volatile aroma components with a method based on characteristic ion profiles. The GC/MS profiles showed a general increase in the concentration of volatile components during storage. The oxidative stability of the butter samples as influenced by the various storage conditions was followed by analysis of 48 volatile components and by determination of the peroxide value (PV). The PV was significantly higher (p<0.05) in the butter stored in the catering plastic container than in the butter in aluminum foil after 14 weeks of storage at 20°C. Among the volatile components analyzed and identified, hexanal was chosen as an indicator of lipid oxidation. The concentration of hexanal was significantly higher (p<0.05) in the butter stored in the catering plastic container than in the aluminum foil after 14 weeks of storage at 20°C. No differènces were found between butter samples stored at -18°C. Both types of butter had a higher content of hexanal (p<0.05) when stored at 20°C than at 4°C and -18°C, respectively. The presence of a higher concentration of hexanal in butter stored in aluminum for 14 weeks at 4°C may be explained by different kinetics of oxidation, butter in plastic having a longer induction period but a steeper rate of autoxidative propagation. Thus the analysis of headspace volatile compounds can be used as an indicator of the oxidative deterioration of butter, and gives, when combined with the PV, a better overall prediction of the development of oxidative changes.