Quantification of patulin in fruit leathers by ultra-high-performance liquid chromatography-photodiode array (UPLC-PDA)

Abstract

Patulin is a mycotoxin commonly found in certain fruit and fruit products. For this reason many countries have established regulatory limits pertaining to, in particular, apple juice and apple products. Fruit leathers are produced by dehydrating fruit puree, leaving a sweet product that has a leathery texture. A recent report in the literature described the detection of patulin at substantial levels in fruit leathers. To investigate this further, an ultra-high-performance liquid chromatography-photodiode array (UPLC-PDA) method was developed for the sensitive detection of patulin in fruit leathers. Investigations were also made of the suitability of direct analysis in real time-mass spectrometry (DART-MS) for detection of patulin from the surface of fruit leathers. Results indicated DART-MS was insufficiently sensitive for quantification from the surface of home-style apple leathers, although patulin spiked onto the surface of leather or peel could be detected. The UPLC-PDA method was used to determine the fate of patulin during the preparation of home-made fruit leathers. Interestingly, when a home-style process was used, the patulin was not destroyed, but rather increased in concentration as the puree was dehydrated. The UPLC-PDA method was also used to screen for patulin in commercial fruit leathers. Of the 36 products tested, 14 were above the limit of detection (3.5 μg kg^–1) and nine were above the limit of quantification (12 μg kg^–1). Positive samples were confirmed by UPLC-MS/MS. Only one sample was found above the US regulatory limit for single-strength apple juice products (50 μg kg^–1). These results suggest patulin can be concentrated during preparation and can be found in fruit leathers. The limited survey suggests that patulin is fairly prevalent in such commercial products, but that the levels are usually low.

Graphical Abstract

Keywords:

• patulin
• fruit leather
• ambient ionisation mass spectrometry
• DART-MS

Acknowledgements

The authors thank Amy McGovern and Chris McGovern of the USDA-ARS in Peoria, Illinois, and Tao Jiang and Wei Yu of Southwest University, ChongQing, for helping them to obtain commercial fruit leathers.

Additional information

Funding

This work was supported by the USDA Agricultural Research Service [project number 5010-42000-045-00D]. L. M. was supported by the National Basic Research Program of China [grant number 2013CB127803] and the National Natural Science Foundation of China [grant number 31301476].