A nondestructive method for oil distribution evaluation in healthy fried food developing by Raman imaging

Deep-fat frying is one of the most popular food processing methods worldwide, which makes fried products tend to have bright color, delicious taste and crisp texture. However, traditional fried foods contain large amount of oil, calories and acrylamide which are burden to health, making consumers increasingly tend to use healthy food with low fat content, reduction of oil uptake during different frying processes is necessary. In this study, fried spring roll wrappers at different temperature were taken as examples to be investigated by Confocal microscopic Raman imaging method. The Raman spectra measured within the fried wrapper were compared with spectra of the main components i.e., raw wrapper and frying oil. In this way, the oil distribution in longitudinal section of the wrappers were determined and corresponding images of the fried wrapper microstructure were generated. Comparing to the commonly used oil distribution detection method of dye oil coupled with confocal laser scanning microscopy (CLSM), Raman imaging method shows great advantages in nondestructive, dye reagent free and can eliminate possible influences of oil dye reagent during frying process. The research showed that Raman imaging method has great potential in analyzing oil infiltration mechanism during frying and help to develop innovative frying technologies to reduce oil absorption during frying process, thus obtain healthier fried products with low oil content.