Volatile compounds analysis and sensory profiling of four colored roasted sweet potatoes via HS-SPME GC-O-MS and HS-SPME GC×GC-TOF MS

Sweet potato (Ipomoea batatas L.) is the fifth largest food crop in the world, and roasted sweet potato is particularly popular among people worldwide. The aim of this study was to investigate the composition and flavor variations of four roasted sweet potatoes with different flesh colors (white, yellow, red and purple) and their relationship with sensory descriptors. Results showed that the starch content of all varieties of sweet potatoes decreased after baking, while the maltose content was significantly increased (p < 0.05) in all of them after roasting. Aroma volatiles were then analysed by headspace solid-phase microextraction/comprehensive two-dimensional gas chromatography-time-of-flight mass spectrometry (HS-SPME / GC × GC-TOF MS), and a total of 120 compounds were identified, with aldehydes having the highest percentage of content in all samples (37%-53.16%). Multivariate statistical analysis of these compounds yielded 63 key difference compounds (VIP > 1, p < 0.05). Combined with gas chromatography-olfactory mass spectrometry (GC-O-MS) technique, 18 main aroma compounds including maltol, β-damascenone and phenylacetaldehyde were identified. Finally, the samples were subjected to sensory evaluation and analysed in combination with the GC-O-MS results. The results showed that the compounds guaiacol, 1-octen-3-ol, maltol, acetic acid, octanal and β-damascenone were positively correlated with burnt, earthy, caramel, sour, green and floral aromas, respectively. These findings may be the main reason for the different aromas of different coloured roasted sweet potatoes and provide new insights into the molecular-level differences in sensory properties of different coloured roasted sweet potatoes.