Purpose: To determine the stability of patulin during pasteurization and storage of apple juice.
Methods: Sample preparation was based on the QuEChERS procedure, involving an initial extraction step with water and acetronitrile, followed by a partitioning step after the addition of magnesium sulfate and sodium chloride. Commercially sterile apple juice was fortified with different levels of patulin, and three QuEChERS sample extraction methods were compared. The cleanup was performed by using dispersive solid-phase extraction with a mixture of magnesium sulfate, primary secondary amine sorbent, and graphitized carbon black. The filtrate was derived with an equal amount of N,O-bis-trimethylsilyl-triflouroacetamide at 60°C for 20 min. GC/MS/MS analyses were optimized on an Agilent 7000A triple quadruple chromatograph. Mass spectrometric data was collected in multiple ion monitoring mode. For patulin stability, apple juice was fortified with either 25, 50 or 100 ppb patulin and stored at three different temperatures for 28 days.
Results: Stability of fortified patulin in clear apple juice was affected by storage time, with the recovery of patulin gradually decreasing as the storage period progressed. Patulin was much more stable at 4°C than at ambient or accelerated shelf-life temperatures. Our results indicate that patulin reduction was time and temperature dependent. Reduction in 50 and 100 ppb fortified patulin levels were more pronounced after 28 d of storage than that of the 25 ppb fortified samples, indicating a concentration effect.
Significance: Although storage for extended periods and heat treatments reduce the level of patulin in apple juice, the reduction is not sufficient to totally eliminate the toxin. This indicates that the selection of raw materials for apple juice manufacturing should be considered as critical for production of apple juice concentrates with low patulin levels.