Ethanol vapor treatment results highly depend on fruit specie

The postharvest life of fruit is inversely correlated to the metabolism rate, especially the respiration rate (Steffens et al., 2007) (*). In order to reduce the metabolism, the main factor managed is the temperature (Saltveit, 2019, Steffens et al., 2007). However, there is an interaction between fruit species and storage temperature on the overall metabolism reduction as a response to decreasing the temperature (Saquet and Streif, 2017, Steffens et al., 2007). Therefore, it is crucial to adequately manage the fruit metabolism during postharvest life to extend the shelf life of fruit and reduce losses. Various technologies have been developed to manage fruit metabolism together with low temperatures, including controlled atmospheres (Argenta et al., 2000, Bekele et al., 2016, DeEll and Ehsani-Moghaddam, 2012, Ho et al., 2013), 1-Methylcyclopropene, 1 MCP,?application (Both et al., 2018, Koushesh Saba and Watkins, 2020, Nock and Watkins, 2013, Watkins, 2006, Yang et al., 2016), aminoethoxyvinylglycine application (Anese et al., 2020, Petri et al., 2010, Whale et al., 2008), and, more recently, ethanol vapor treatment (Ji et al., 2019, Jin et al., 2013, Nunes et al., 2019, Pesis, 2005, Thewes et al., 2021b, Weber et al., 2016, Weber et al., 2020). All these technologies help reduce fruit metabolism and extend the shelf life. Nevertheless, when fruit metabolism is managed with ethanol vapor, the temperature to which the fruit are exposed to the ethanol may lead to a particular interaction. Ethanol is an intermediary metabolite of fruit metabolism and is actively converted to other compounds, such as ethyl esters (Nunes et al., 2019, Thewes et al., 2017, Thewes et al., 2021b, Weber et al., 2020, Wright et al., 2015). Thus, evaluating the interaction between the temperature of ethanol vapor treatment and fruit species on ethylene production and respiration rate is pivotal, as it is unclear how these factors interact with fruit metabolism. Additionally, knowing these interactions is important for practical recommendations of ethanol use. The objectives of this study were to: i) determine the effect of temperature on the ethanol vaporization rate, ii) determine the effect of temperature on the uptake rate of fruit species and cultivars,iii) understand the relationship between the temperature that ethanol is applied, ethylene metabolism, and respiration rate of fruit, andiv) evaluate the interaction between temperature that fruit are submitted to ethanol treatment on the metabolites produced by them as a response to ethanol treatment. The ethanol vaporization rate was performed in an empty container experiment at 2, 10, and 20 ?C. Four experiments were conducted to identify the ethanol uptake rate in ?Maxi Gala? and ?Cripps Pink? apples, ?BRS Isis? table grapes, and ?Rojo Brillante? persimmons at 2, 10, and 20 ?C. The metabolites produced by the fruit as a response to the ethanol treatment were determined using HS-SPME-GC/MS analysis. Our findings showed that the ethanol vaporization rate increases exponentially with the temperature and has a linear relationship with time. Moreover, the temperature and fruit species/cultivar affected the ethanol uptake rate, with the highest uptake rate at 20 ?C. Furthermore, ethanol vapor uptake rate was positively correlated to respiration rate when all fruit species/cultivars were evaluated together, showing that fruit metabolism affects ethanol uptake rate. The temperature impacted the metabolite produced by fruit from ethanol application, evidencing the possibility of managing the volatile compounds produced from ethanol based on the ethanol treatment temperature. The fruit species has a decisive impact if ethanol is esterified or transformed to acetaldehyde, being predominantly esterified in apples and grapes, and converted to acetaldehyde in persimmons. Ethanol vapor treatment reduced the ethylene metabolism in apples at 20 ?C, although ethanol increased ethylene in persimmons at 2 ?C. Moreover, the respiration rate was generally unaffected or reduced in ethanol-treated fruit compared to untreated fruit of the same species/cultivar. (*) Quotes in the original paper SourcesDynamics of ethanol and its metabolites in fruit: The impact of the temperature and fruit speciesFabio Rodrigo Thewes, Auri Brackmann, Vanderlei Both, Vagner Ludwig, Lucas Mallmann Wendt, Flavio? Roberto Thewes & Francis J?nior SoldateliPostharvest Biology and Technology?Volume 197, March 2023, 112209https://www.sciencedirect.com/science/article/abs/pii/S0925521422003775https://doi.org/10.1016/j.postharvbio.2022.112209Picture of ethanol by Pixabay