Short-term changes in the aromatic profile of fresh sweet basil (Ocimum basilicum) using sensory and chemical temporal methods

Fresh sweet basil was evaluated for its changing aromatic profile over a 10-minute period by ten trained panelists using TCATA and two GC methods (SPME and ITEX). Results show human panelists were able to detect a change in the short-term aromatic profile of fresh sweet basil, whereas the GC methods were only able to create initial aromatic profiles. Fresh sweet basil (Ocimum basilicum) is known for its distinct aromatic profile from the release of volatile compounds upon damage to the leaves from cutting, tearing, or chewing. Anecdotal evidence suggests that the aromatic profile changes rapidly over a brief period and may be associated with the loss of characteristic ‘spicy’ notes which could be important to consumers. This study documented short-term changes in the sensory profile as well as the volatile chemical composition of fresh sweet basil leaves. Temporal check-all-that-apply (TCATA) methodology was used to track the changes in the sensory profiles over time. Ten trained panelists selected sensory attributes from a list of 10 sensory attributes distilled from an established lexicon and repeated this evaluation in 1-minute intervals for a total of 10-minutes. Four fresh basil samples were evaluated: Keira and Lucia varieties sourced from Soli organic, and two commercial basils (unknown varieties) marketed by Edible Gardens and Goodness Gardens. Two gas chromatography (GC) methods were pilot tested to track chemical changes across the same time-period; solid phase microextraction (SPME) GC, a static method, and in-tube extraction (ITEX) GC, a dynamic headspace method. The static method samples from a headspace in equilibrium, whereas a dynamic method simulates free-flowing air by disrupting the equilibrium. It was hypothesized that the dynamic method would correlate better to the sensory data given how it more closely resembles the environment of the panelists. TCATA identified differences at Time 0 in the overall sensory profiles and successfully tracked these changes over time. There were decreases in ‘spicy’, ‘anise’, and ‘clove’ aromas and a corresponding increase in ‘green/grassy’ aromas over the 10- minute period. Both GC methods produced chemical profiles that strongly correlated with the sensory profiles at Time 0, but neither GC method was able to effectively capture changes over time. These results emphasize the importance of sampling time with fresh sweet basil given how rapidly the profile changes. Future studies will determine the extent to which staying power and duration of aromatic intensity are important to consumers, informing breeding decisions for new varieties.