The effect of short-term high CO2 on maintaining postharvest cherimoya (Annona cherimola Mill.) fruit quality during storage at low temperature was analyzed. Pretreatment with an atmosphere of 20% CO2 and 20% O2 for 3 days retained fruit firmness and prevented an increase in the immunodetected levels of polygalacturonase-related protein during storage at 6 °C. Color scale values, chlorophyll content, and levels of the immunoreactive large subunit of ribulose 1,5-biphosphate carboxylase protein were higher in treated than in air-stored fruit. Short-term high CO2 treatment had a long residual effect at low temperature and improved storage life by preventing fruit softening and delaying senescence-like responses in green peel of cherimoya fruit tissues.
María I. Escribano, Begoña Del Cura, Teresa Muñoz and Carmen Merodio
Teresa Muñoz, Jesús Ruiz-Cabello, Antonio D. Molina-García, María I. Escribano and Carmen Merodio
Phophorous nuclear magnetic resonance (31P-NMR) spectroscopy was used to study the vacuolar and cytoplasmic pH and the inorganic phosphate (Pi) pool distribution in `Fino de Jete' cherimoya (Annona cherimola Mill.) fruit stored at a chilling temperature (6 °C). Fruit stored at the ripening temperature (20 °C) for 3 days were used as a control. 31P-NMR results confirmed that 6 °C storage caused cytoplasmic acidosis (a decrease of 0.72 ± 0.08 pH units) and a notable increase in the amount of Pi in the cytoplasm. Spectra of perchloric acid extracts also revealed that storage at 6 °C was associated with an increase in the total amount of Pi and phosphorylated metabolites. Moreover, perfusion experiments with a phosphate medium confirmed the preferential accumulation of Pi in the cytoplasm in chilled tissues. Specific activation of phosphoenolpyruvate carboxylase (PEPC) (32.1 ± 1.7 μmol·min-1·mg-1) was observed in those fruit. In chilled fruit the amount of ADP was held at steady-state levels and ATP levels increased, contrary to observations for ripe fruit, where the pool of total nucleotides decreased beyond the point of NMR detection. Fruit stored at 6 °C exhibited a low respiration rate, but metabolism was not arrested and an increase in total soluble solid contents was also observed.
Begoña Del Cura, María I. Escribano, Jose P. Zamorano and Carmen Merodio
The peel of `Fino de Jete' cherimoya (Annona cherimola Mill.) stored at 20 °C in air and in an atmosphere with high levels of CO2 was analyzed for changes in protein levels, color, chlorophyll content, and firmness. The accumulation of immunoreactive proteins was studied using Rubisco and polygalacturonase antibodies. During storage in air, cherimoya peel tissues exhibited a decrease in chlorophyll content and an immunodetected drop in the abundance of the large subunit of ribulose 1,5-biphosphate carboxylase (LSR). An immunodetected rise in polygalacturonase (PG)-related protein was quantified. High CO2 levels delayed the softening of cherimoya fruit, retarded the maximum accumulation of PG-related protein, and maintained LSR levels, greenness, and chlorophyll content of peel tissues.