Effect of short heat treatments with a sodium bicarbonate solution on storability of the yellow germoplasm plum 'Meloni'

Abstract

The behavior of a Sardinian plum, cv. Meloni, was investigated with regard to short-heat treatments at 20, 50, 55 or 60°C in water with 0 or 2% NaHCO3 (SBC) for 0, 15, 30, 45 or 60 seconds. Fruits were stored for one month at 5°C and 95% RH followed by a simulated marketing period (SMP) at 20°C and 80% RH for six days. Quality and decay percentage
were monitored. In addition, fruits were artificially inoculated with P. expansum and stored for 10 days at 25°C and 95% RH. Compared to the control, all short-heat dip treatments lowered the degree of decay, and the efficacy was positively correlated with temperature and treatment duration. The use of SBC increased the efficacy of decay control and the best results were attained at 55 and 60°C. Heat treatments increased levels of total flavonoids and antioxidant activity after SMP. None of the heat treatments induced rind damage (browning or discoloration), but the overall appearance decreased significantly when fruit was treated at 55 or 60°C for 60 s after SMP. Scanning electron microscopy (SEM) observations showed that treatments at 55 and 60°C with SBC cause damage and loss of cuticular wax on fruit surface.