A long shelf life is of utmost importance when it comes to storage of food. Oats are expected to be easy to store like other cereals. However, oats that are stored for a long period of time are susceptible to becoming rancid, owing to its high lipid content. The lipids are mostly unsaturated fatty acids and prone to deterioration by native lipases which release fatty acids like oleic, linoleic and palmitic acids that cause a bitter flavour. Unsaturated fatty acids are also prone to oxidation, increasing the risk of deterioration and formation of unpleasant lipid oxidation products, which also contribute to the bitter flavour. As a solution, industries often use harsh heat treatments to inactivate lipases which significantly increase the shelf-life of the oats. The treatments however may end up increasing lipid oxidation. Hence, a need for the perfect combination of heat treatment and storage condition arises to maximise the shelf life of oats.
In this study, several mild to harsh heat treatments were studied in combination with different storage conditions for 8 weeks. The heat treatments were a combination of steaming and drying, where one was steamed and dried at 70°C, another at 100°C, and the last one was steamed at 70°C and dried at 100°C. The oats were stored in dark at 4°C, 40°C and room temperature and in light at room temperature. It was found from the lipase assay that the heat treatments inactivated lipases effectively. The lipid profile was studied on the GC and the appearance of aldehydes was checked on the HPLC. A microbial study was also performed to check the functionality of the storage conditions as a form of quality control measure.
It was found that the heat treatments combined with the storage conditions did have an effect on the oats throughout the eight weeks. All the treated oats showed
accumulation of fatty acids over time and this was probably due to the combined effect of the treatments and storage conditions. The oxidation of lipids was also studied alongside using peroxide value analysis and development of aldehydes. In addition, no growth of spoilage micro organisms was found in any of the treatments throughout eight weeks.