Apple fruit recovery from anoxia under controlled atmosphere storage.

This study investigated the dynamic changes in the anaerobic metabolism end products (ethanol, acetaldehyde and ethyl acetate) of different apple cultivars during 84-days of regular air (RA) and controlled atmosphere (CA) storage after 0-, 3-, 7- and 14-days of anoxia. Increasing the length of exposure to anoxia increased the anaerobic metabolites concentrations (AMC) in all cultivars. Fruit could recover from anoxia, and the AMC dissipated after 84-days of storage under both storage systems when the duration of anoxia was <7-days. The rate of metabolite dissipation following 14-days of anoxia differed among cultivars and storage systems. The reduction in AMC was faster under CA than RA-storage for 'Golden Delicious' and 'Jonagold' fruit, while the opposite trend was observed for 'Kanzi'. These results indicate that storage under CA post anoxia maintains better fruit quality during 84-days of storage than RA and effectively reduces the AMC.

Influence of respiratory quotient dynamic controlled atmosphere (DCA - RQ) and ethanol application on softening of Braeburn apples.

The effect of a respiratory quotient dynamic controlled atmosphere (DCA - RQ), which induces ethanol production through low oxygen storage, and ethanol application on softening of Braeburn apples stored at different temperatures was investigated. DCA - RQ storage was associated with the activation of the alcohol dehydrogenase (ADH) and greater anaerobic metabolism in comparison with DCA - CF (chlorophyll fluorescence) and controlled atmosphere (CA) storage. Greater anaerobic metabolism resulted in lower ethylene production, ACC oxidase activity, membrane permeability, -galactosidase activity and, therefore, less softening after long-term storage. Ethanol application after CA storage decreased ethylene biosynthesis, respiration rate and membrane permeability. Storage at 3 °C resulted in the lowest soluble solids and acidity, but not softening. In conclusion, Braeburn apples could be stored at 3 °C under DCA - RQ1.5. Additionally, ethanol produced by the fruit, or applied externally, had a significant effect on inhibiting softening during and after storage.

Dynamic controlled atmosphere: Impact of elevated storage temperature on anaerobic metabolism and quality of 'Nicoter' apples.

The aim of the study was to evaluate an elevated (3.0 °C) and low (1.0 °C) storage temperature combined with dynamic controlled atmosphere monitored by respiratory quotient (DCA-RQ) and chlorophyll fluorescence (DCA-CF) on anaerobic metabolism, physiological storage disorders and overall quality of 'Nicoter' ('Kanzi®') apples after 5.5 and 8.0 months of storage plus 7d shelf-life. Fruit stored under DCA-RQ 2.0 accumulated the highest amounts of anaerobic metabolites (acetaldehyde, ethanol and ethyl acetate), regardless of storage temperature and timing of storage outturn evaluation, but it did not result in higher electrolyte leakage. Flesh breakdown, core breakdown and cavity formation were reduced at 3 °C. Storage at 3 °C combined with DCA maintained higher flesh firmness after 8.0 months storage plus 7d shelf-life. 'Nicoter' apples can be stored at 3 °C using a DCA system, based either on CF or on RQ, to save electrical energy.

Changes in polyphenols and expression levels of related genes in 'Duke' blueberries stored under high CO2 levels.

Blueberries are highly perishable fruits, and consequently, storage under high CO2 and low O2 levels is recommended to preserve the highly appreciated polyphenols. However, high CO2 levels might be detrimental for certain cultivars. The aim of this study was to investigate the impact of storage conditions on various quality parameters, including polyphenol composition in 'Duke' berries. Results show that storage under 18 kPa CO2, coupled with 3 kPa O2, resulted in accelerated softening of berries, which was accompanied by lower levels compared to other conditions of hexosides and arabinosides of malvidin, petunidin, cyanidine, and delphinidin. However, this storage condition had no negative impact on chlorogenic acid levels. Expression data of key polyphenol-biosynthesis genes showed higher expression levels of all investigated genes at harvest time compared to all storage conditions. Of particular importance is the expression level of chalcone synthase (VcCHS), which is severely affected by storage at 18 kPa CO2.

Correlation between changes in polyphenol composition of peels and incidence of CO2 skin burning of 'Cameo' apples as influenced by controlled atmosphere storage.

'Cameo' apples stored under high CO2 levels suffer from "skin burning". Accordingly, this study is aimed to correlate the incidence of skin burning with different polyphenols. After harvest, apples were sorted into bad- and good-colored fruit and further stored under either high (3%) or low (0.7%) CO2 level. At frequent intervals, fruit were assessed for incidence of skin burning and relative concentrations of various polyphenols. Results clearly show that bad-colored apples stored under high CO2 level had the highest incidence percentage. Concerning the polyphenol profile, good-colored and healthy apples had significantly higher concentrations of certain polyphenols, including cyanidin-3-galactoside and rutin. However, bad-colored and injured apples had significantly higher concentrations of another set of polyphenols, including phloridzin, epicatechin, and (epi)catechin→(epi)catechin isomers. Taking into account that quercetins and cyanidins account for more than 80% of antioxidants, it is logical to assume that these polyphenols might give protection to good-colored apples against skin burning.