Articles
INFLUENCE OF POSTHARVEST TEMPERATURE AND CONTROLLED ATMOSPHERE CONDITIONING ON O’HENRY PEACH STORAGE DISORDERS
Fruit so injured may appear normal when removed from cold storage, but do not ripen satisfactorily at high temperature.
The resulting internal breakdown symptoms can include tissue browning, a dry mealy texture when ripe (woolliness or mealiness), failure to ripen, failure to develop normal flesh color (sometimes reddening of the flesh), and usually a loss of characteristic flavor.
The incidence of chilling injury can be reduced by a delay of cooling after harvest, although fruit softening occurs.
To reduce postharvest physiological disorders, peach fruit cv. ‘O’Henry’ were subjected to conditioning for 48 h at 18°C prior to cold storage, and to avoid pulp firmness loss, controlled atmosphere storage with combination of three levels of CO2 (0, 5 and 10%) and two levels of O2 (5 and 21%) were used during the conditioning.
The control fruit was hydrocooled after harvest and then cold stored, and the CA treatment fruits were hydrocooled after the conditioning period.
Fruit were packed in plastic trays covered with a perforated plastic bag and put into commercial wooden shipping boxes that were kept in their respective sealed CA containers while conditioning.
Fruit evaluations were made after 21 and 28 days of cold storage (0°C and 85–90% RH) and after 3 and 5 days at 18°C as ripening periods.
Fruit quality parameters (ground color, fruit firmness, soluble solids content, pH, titratable acidity, SSC/TA ratio, fresh weight loss and decay) and physiological disorders (woolliness, internal browning and reddening of the flesh) were determined.
The experiment was a completely randomized design with 30 replications per treatment, and the experimental unit was the fruit.
Fruit cold stored directly after harvest (control) did not show a decrease in fruit firmness (6.7 kg) compared with the conditioned fruit (air treatment) for 48 h at 18°C which presented the highest fruit firmness loss of all treatments (3.2 kg). Increasing CO2 and decreasing O2 levels avoided fruit firmness loss during conditioning, and at 21 and 28 days cold stored at 0°C as compared with the air control treatment.
Nevertheless, the ripening period of 3 days at 18°C produced a rapid decrease in fruit firmness, with no major differences being found among treatments after 5 days of ripening with firmness values of 0.6 to 0.8 kg.
Soluble solids content (9 – 10%), pH (3.9 – 4.1), titratable acidity (0.6% malic acid) and SSC/TA (16 – 18) did not show differences among treatments.
The development of woolliness in cold stored fruit could only be measured after 3 days of ripening from fruit cold stored at 21 days and for the ripening period of 5 days after cold storage for both 21 and 28 days.
This was caused by the high values of fruit firmness and to the subjective methodology used in the study since woolliness was assessed subjectively by squeezing the fruit to determine the available amount of juiciness.
From the results obtained in this study we concluded that woolliness (mealiness) was the only chilling injury disorder detected and was not reduced with elevated temperature conditioning prior to cold storage.
Controlled atmosphere (5–10% CO2 and 5% O2) helped to control pulp firmness loss but not woolliness.