Genotypic identification of Penicillium expansum and the role of processing on patulin presence in juice

This work aimed at isolation and identification of patulin producing fungi and to follow the presence of patulin during apple juice processing. Among 34 Penicillium isolates, eight isolates (five from healthy appeared apples and 12 from rot spotted apples) were considered as patulin producers using thin-layer chromatography. These isolates were classically identified as a Penicillium expansum. PCR utilizing primers based on the polygalacturonase gene of P. expansum was applied for detecting this mold. The PCR amplified a 404-bp DNA product from all tested P. expansum isolates, but not in other common food spoilage Penicillium species. RAPD technique using P1 or M13 primers was applied to determine the similarity of the P. expansum isolates. RAPD results revealed that the tested strains showed high percentage of similarity and no correlation was observed between cluster analysis and the sources of isolation. Patulin could not be detected in healthy appeared apples and their extracted juice during different stages of juice process. In apple juice made from the healthy parts of apples decayed by P. expansum contained patulin which may present health hazard. The obtained results assured that patulin is known to be stable in apple juice even after pasteurization. In conclusion, the removal of the rotten part from the fruit is not sufficient to eliminate the mycotoxin patulin from apple juice. Although, the enzyme treatment (pectinase and amylase) and pasteurization (95 °C for 7 min) significantly (p < 0.05) reduced patulin level, its level is still higher than the level of <50 μg/kg considered by Codex alimentarius when the apple juice processed from the healthy parts of rot spotted fruits.