## 4 Conclusions  
The study demonstrated that the application of PEF treatment influenced the volatile profile of onions based on the applied electric field strengths. The intensity of PEF treatment was correlated to the differences in the extent of cellular disruption, which resulted in the mixing of enzyme and substrates, thus facilitating reactions to generate the volatile compounds of interest. The impact of PEF treatment on the volatile compounds were found to be consistent between the three onion cultivars tested. However, quantitative differences in the volatile concentrations were observed between the cultivars, correlating to tissue type and maturity. The highest concentrations of volatile sulfur compounds were observed after 24 h incubation following a high-PEF treatment, compared to the untreated samples. Across all three cultivars, the volatile sulfur-containing compounds such as DPDS, PPrDS, DPTS, MPDS, PPrTS, and MPTS, were found to be significantly affected by PEF treatment intensities and could act as markers of cell membrane damage. This study also suggests that PEF treatment could be tailored for different applications based on the specific fruit and vegetable tissue. Moreover,  
Figure 6: Mean (\(n=8\)) ion counts of alkanes (nonane, decane, and undecane) in control and PEF-treated onion samples. Bars with different letters indicate statistically significant difference (Fisher’s LSD, \(p<0.05\)). Error bars represent standard error of the mean.  
these volatile compounds could also be used as markers to detect damage or deterioration in fruit and vegetables tissues.  
The following are available online at [[http://www.mdpi.com/2304-8158/7/11/183/s1](http://www.mdpi.com/2304-8158/7/11/183/s1)]([http://www.mdpi.com/2304-8158/7/11/183/s1](http://www.mdpi.com/2304-8158/7/11/183/s1)). Table S1: Volatile compounds in control and PEF-treated samples of Red Bunching onions (immediately after PEF and 24 h after PEF), Table S2. Volatile compounds in control and PEF-treated samples of Ishikura onions (immediately after PEF and 24 h after PEF), Table S3. Volatile compounds in control and PEF-treated samples of Yellow sweet Spanish onions (immediately after PEF and 24 h after PEF), Table S4. Results of ANOVA representing the volatile compounds in onion varieties upon PEF treatment.  
[PERSON], [PERSON] and [PERSON] conceived and designed the experiments; [PERSON] performed the experiments; [PERSON], [PERSON], [PERSON] and B.K. analyzed the data; and [PERSON], [PERSON], [PERSON], [PERSON] and B.K. wrote the paper.  
The research was carried out as a part of the Food Industry Enabling Technologies programme funded by the New Zealand Ministry of Business, Innovation and Employment (contract MAUX1402) and supported by the New Zealand Onion Industry. This research was also supported by the Riddet Institute, a New Zealand Centre of Research Excellence, funded by the Tertiary Education Commission.  
The authors acknowledge the University of Otago Doctoral Scholarship and the postgraduate publishing bursary towards the Ph.D. study of [PERSON].  
The authors declare no conflict of interest. The funding sponsors had no role in the design of the study; in the collection, analyses, or interpretation of data; in the writing of the manuscript; or in the decision to publish the results.