Effect of Frying Process on the Flavor Variations of Allium Plants

The Allium plant is widely used in cuisines around the world for its characteristic flavor. The general profile of the plant changes a lot and presents quite different smells after the frying process. In this work, five Allium plants and their fried oils were compared to find out how the frying process impacts the general flavor profile. The results of sensory analysis indicated that the frying process could substantially increase the flavor acceptability of fresh Allium plants. Meanwhile, according to gas chromatography-mass spectrometry (GC-MS) analysis, fewer volatile compounds were detected in fresh Allium plants than in their fried oils. Furthermore, contents of nitrogen-containing compounds (ranging from 0.17 μg/g to 268.97 μg/g), aldehydes (ranging from 71.82 μg/g to 1164.84 μg/g), and lactones (ranging from 0 μg/g to 12.38 μg/g) increased significantly. In addition, more aroma-active substances were identified in the fried Allium oils revealed by gas chromatography-olfactometry (GC-O) analysis. Sulfur-containing compounds were the most abundant in fresh Allium plants, whereas nitrogen-containing compounds dominated in fried oils. The thermal degradation of sugars, amino acids and lipids as well as interactions between carbohydrates, proteins, and fats during the frying process were thought to be the main contributors to these variations. Therefore, this research provides a theoretical basis for the quality control of onion oil flavor and promotes the further development of the onion plant industry. Consequently, the research provided a theoretical basis for the quality control of Allium oils' flavor and promoted the further development of Allium plant industries.