Development of bruising and ethylene, CO2, and respiration rate in damaged bananas Ariane McCorquodale Hi everyone, my name is Ariane and I was interested in using gas chromatography to monitor ethylene, CO2, and respiration rate in bananas that received different amounts of bruising.

Methods Treatments No bruise Bruised once Bruised twice Bananas were bruised by dropping a ball bearing through a pvc tube from a height of 62 cm Measurements on ethylene and CO2 taken via gas chromatography and bridge analyzer Each banana was labeled with its group ID with permanent marker. To inflict bruises, each treatment banana was placed under a 62 cm pvc vertical tube and a ball bearing was dropped through the tube to a central impact point on the banana. A total 18 bananas were bruised either once, twice or not at all for (6 per treatment). For each treatment group, bananas were placed 3 to a jar (2 jars per treatment). Jars were sealed with foil tape and each lid had two rubber septa for taking samples. The jars were left sealed for 24 hrs on the first night, which was accidental, but did manage to capture some spikes (see results). For each subsequent reading jars were sealed for approximately 1 hr. Initially, readings were taken in the order control, bruised once, and bruised twice. I switched this sequence up on 10/17 to account for the fact that early readings might have lower concentrations of ethylene and CO2 than readings taken later in the sequence. Ethylene readings were taken using the gas chromatography (GC) machine. Carbon dioxide readings were initially taken with the GC but then the GC failed to detect any CO2 so I switched to taking readings with the bridge analyzer. The respiration rate was calculated from the CO2 data and the time sealed.

Control 10/11 10/15 10/17 10/19 10/21 These slides demonstrate the ripening and bruising severity over time.

Bruised Once 10/11 10/15 10/17 10/19 10/21

Bruised Twice 10/11 10/15 10/17 10/19 10/21 By the last day one of the bananas was starting to liquefy and ferment. Other than that there is not much of a notable difference between the bruised once group and the bruised twice group.

Results: Ethylene Trend well until 10/19 Second spike is interesting There is a nice spike in ethylene for the first 24 hrs and then it drops before spiking even more. I wonder if this has something to do with the fact the bananas were suffocated for 24 hrs initially. Perhaps some reactions could not occur in the temporarily low-oxygen environment that were then able to progress once the jars were unsealed; like some sort of delayed damage response. Or perhaps this is normal… who knows? (not me) Towards the end of the experiment the levels kind of go all over the place. This might have something to do with my switching up the sequence of the gas chromatography readings or it could just be that the ripening is too advanced for previous damage to have influence. If it is a matter of the order in which the readings were taken then I cannot make any conclusions from this graph.

Results: CO2 No correlation with bruising There is no obvious correlation between CO2 and treatment, but there is a nice spike and a steady climb over time as the fruit ripens.

Results: Respiration Rate Again, no correlation Interestingly, the respiration rate took a dive after the bananas were sealed for 24 hrs. This makes sense as CO2 is a product of aerobic respiration, which requires oxygen, which the bananas did not have in abundance due to their being sealed for 24 hrs. So even though there was a spike in the amount of CO2 for the first 24 hrs, the rate at which it was being released was far lower than for the bananas that were allowed to “breathe.” As ripening progresses the respiration rate continues to increase. Again there is an interesting second spike like we saw with ethylene.

Conclusions No strong correlations observed for CO2 and respiration rate Bruising was notably more severe on bananas that were bruised twice All in all, I am not comfortable making any conclusions from my data based on treatment, but it was interesting to see how ethylene, CO2, and respiration rate changed over time and in response to being sealed for 24 hrs. Perhaps some revisions to my experimental design would yield better results. Thank you for your time! Questions can be emailed to amccorquodale@ufl.edu.