Impact of Pseudomonas graminis strain CPA-7 on respiration and ethylene production in fresh-cut ‘Golden delicious’ apple according to the maturity stage and the preservation strategy

Abstract

The effect of the biocontrol agent (BCA) Pseudomonas graminis CPA-7 on the accumulation of CO2 and ethylene (C2H4) in fresh-cut apples at two maturity stages was evaluated in refrigerated conditions. Factors involved in the preservation strategy applied upon commercial conditions such as the antioxidant (AOX) treatment and the storage system were included in the analysis. Regardless of the maturity stage, the BCA reduced C2H4 levels within the MAP atmosphere in AOX-untreated apples wedges, by 29 and 43% in immature and mature apples, respectively. Nevertheless, the addition of ascorbate as antioxidant counteracted this effect. In vitro tests suggested that the reduction of C2H4 levels was not associated to the uptake of this molecule by CPA-7. Interestingly, in non-inoculated samples AOX treatment showed contradictory effects on C2H4 production in MAP conditions by significantly reducing C2H4 levels in immature apples (by 23%) while increasing it in mature ones (by 40%). Similarly, CPA-7 had opposite effects on the CO2 accumulation pattern depending on the storage system or the fruit maturity stage. In this sense, CPA-7 was associated to a higher fruit respiratory activity at an advanced maturity stage yet without inducing the fruit fermentative metabolism or altering the fruit quality during a week of refrigerated storage. Overall, these results show that CPA-7 may contribute to the maintenance of the microbiological and physicochemical quality of fresh-cut apple by modulating the fruit ethylene production and/or respiration.