Thermal and structural changes of rapeseed oil during isothermal storage at low temperature

Publication date: Available online 9 December 2016 Source:Food Structure Author(s): Yayoi Miyagawa, Keisuke Shintani, Kazutaka Katsuki, Kyuya Nakagawa, Shuji Adachi The crystallization behavior of rapeseed oil during isothermal storage was investigated using differential scanning calorimetry (DSC), and wide-angle and small-angle X-ray scattering analyses. Rapeseed oil is composed of many kinds of triacylglycerols. When this oil was cooled to its freezing temperature, a meta-stable phase was immediately formed. After a certain period, exothermal crystallization was induced. DSC analysis showed that the induction period, which is defined as the time from the beginning of isothermal storage until an exothermal change is detected, was affected by the storage temperature but not by cooling rate and sample size. Exothermal behavior after the induction period at −25°C was different from those stored at −17 and −20°C. X-ray scattering analyses clarified that this difference was due to differences in the formation of the meta-stable phase during the induction period. At −17 and −20°C, the triple chain-length (3L) structure transformed to a double chain-length (2L) structure, where the β form was the dominant component. In contrast, at −25°C, the 2L structure was formed while maintaining the 3L structure, and further structural changes were not observed during storage. It has been suggested that the induction period for the crystallization behavior of rapeseed o...
Source: Food Structure - Category: Food Science Source Type: research