Effect of the Yeast Rhodosporidium paludigenum on Postharvest Decay and Patulin Accumulation in Apples and Pears

The effect of a strain of marine yeast Rhodosporidium paludigenum on postharvest blue mold and patulin accumulation in apples and pears stored at 23 degrees C was evaluated. The occurrence and severity of apple and pear decay caused by Penicillium expansum were significantly inhibited by R. paludigenum. However, the application of the yeast at a high concentration (10(8) cells per ml) enhanced patulin accumulation after 7 days of storage; the amount of patulin increased 24.2 times and 12.6 times compared to the controls in infected apples and pears, respectively. However, R. paludigenum reduced the patulin concentration in the growth medium by both biological degradation and physical adsorption. Optimal in vitro patulin reduction was observed at 30 degrees C and at pH 6.0. R. paludigenum incubated at 28 degrees C was tolerant to patulin at concentrations up to 100 mg/liter. In conclusion, R. paludigenum was able to control postharvest decay in apples and pears and to remove patulin in vitro effectively. However, because the yeast induced patulin accumulation in fruit, the assessment of mycotoxin content after biological treatments in postharvest decay control is important. R. paludigenum may also be a promising source of gene(s) and enzyme(s) for patulin degradation and may be a tool to decrease patulin contamination in commercial fruit-derived products.