Recent neuroscience studies using fMRI have shown specific cortex activities are associated with scent stimuli. This has shed light on the use of EEG for investigating the neuronal processes and effects of olfactory sensory. While there were a few EEG studies using ERP or spectral power analysis, the results are often not converging or lack of generality. This study attempts to explore a potentially more generalized approach by looking into the connectivity patterns in the brain during olfactory sensing. Human olfactory system collects odorants and transduces them into neural signals which are transmitted to the olfactory bulb that connects to the orbitofrontal cortex for further processing. We study connectivity of cortex signal through the coherence analysis on scalp EEG data. We propose a novel protocol for robust olfactory stimulus identification and synchronization experiment. We adopt Magnitude Squared Coherence Estimation for coherence analysis and derived a coherence index (CI) to infer the collaborative effect derived from a region of interest, e.g., left side and right side of scalp. From the 14 subjects' EEG data, we observe the lateralization effect of olfactory processes in the human brain. The results suggest a stronger collaborative effect in the left hemisphere compare to the right side when pleasant stimuli are delivered.