Superficial scald development in 'Granny Smith' and 'Nicoter' apples: The role of key volatile compounds when fruit are stored under dynamic controlled atmosphere.

A positive correlation of α-farnesene and its oxidation metabolites with superficial scald is commonly reported in apples stored in air or controlled atmosphere (CA) systems, where O2 levels are above the lower oxygen limit (LOL) tolerated by the fruit. Nevertheless, the LOL can be monitored by the dynamic controlled atmosphere (DCA) techniques and to provide different physiological responses. Therefore, this study aimed to evaluate key volatile metabolites from 'Granny Smith' and 'Nicoter' ('Kanzi®') apples stored under dynamic controlled atmosphere (DCA) monitored by respiratory quotient (RQ), i. e. at extremely low oxygen partial pressures (ELO) and correlate their emissions with the incidence of superficial scald (SS). The volatile compounds (VCs) were isolated by solid phase microextraction (HS-SPME) and analyzed by gas chromatography. For the first time, higher concentrations of α-farnesene and its oxidation metabolites (6-methyl-5-hepten-2-one, and 6-methyl-5-hepten-2-ol) were negatively correlated with SS in DCA-RQ. This is likely due to the higher levels of ethanol in fruit stored under this condition having an inhibitory effect on SS incidence even when α-farnesene, 6-methyl-5-hepten-2-one, and 6-methyl-5-hepten-2-ol accumulate. Additionally, SS is more correlated to internal ethylene concentration (IEC) than α-farnesene accumulation and their metabolites, even when fruit were stored under ELO, where ethylene action is reduced.

The effects of soybean storage under controlled atmosphere at different temperatures on lipid oxidation and volatile compounds profile.

This study aimed to evaluate the effects of low oxygen partial pressure (pO2) and high carbon dioxide partial pressure (pCO2) combined with different temperatures on the oil acidity and peroxide values of two soybean cultivars (NA 5909 RG and FEPAGRO 37 RR). The volatile compounds correlated to lipid oxidation were also evaluated. Soybeans were stored for seven months under ambient and controlled atmosphere (CA) conditions at three temperatures (20, 25, and 30 °C). Storage under ambient conditions increased acidity and peroxide value regardless of the temperature. CA storage with low pO2 reduced oil acidity and its combination with high pCO2 had no positive effects on oil acidity and peroxide values. Grains of FEPAGRO 37 RR stored under ambient air showed higher 1-octne-3-ol amount compared to CA. The higher storage temperature increased (E)-2-heptenal and decanal amount in grains of cultivar NA 5909 RG. In addition, the ambiente air storage provide higher γ-Butyrolactone in relation to CA storage. Moreover, in both cultivars the CA storage technique provides lower (E)-2-hexenal content. This compound, together with hexanal are potential lipid deterioration markers of soybeans. CA storage is a promising tool for soybean grains preservation and the effect is mainly due to the oxygen reduction, with no additional effect of CO2 increasing.

Key volatile compounds of 'Fuji Kiku' apples as affected by the storage conditions and shelf life: Correlation between volatile emission by intact fruit and juice extracted from the fruit.

For the 'Fuji Kiku' apple, this study aimed: (i) to evaluate the volatile compounds (VCs) from headspace storage chambers with static controlled atmosphere (CA) and with dynamic controlled atmosphere based on chlorophyll fluorescence (DCA-CF) and based on respiratory quotient (DCA-RQ1.5) at ninth month of storage, during 1 and 7 days of shelf life of intact fruit, and in apple juice headspace and (ii) to determine the correlation of the VCs in the headspace from storage chambers and fruit during shelf life with the headspace VCs from apple juice as markers of quality. The VCs were isolated by solid phase microextraction (HS-SPME) and analyzed by gas chromatography. In the storage chambers, ethyl linear chain esters were detected mainly in DCA-RQ1.5, while acetaldehyde and (E)-2-hexenal were more abundant in DCA-CF. At seven days of shelf life, fermentative metabolic compounds had reduced emissions given the opening time of the chamber, while there were higher emissions of branched chain esters, especially ethyl 2-methyl butanoate in DCA-RQ1.5. The correlation was high and positive between the VCs present in the juice and those emitted by the intact fruit during seven days of shelf life, demonstrating that the concentration of VCs in juice can be used to estimate the emissions from whole fruit. DCA-RQ1.5 storage promoted the synthesis of VCs typical of the 'Fuji' apple aroma after a prolonged storage period, even under extremely low partial pressure of oxygen (average 0.15 kPa), contributing to better quality control of characteristic fruit odor and aroma.