Reducing patulin levels in apple juice by fermentation with Saccharomyces cerevisiae

Abstract: Patulin is a mycotoxin that can be found in many apple products all over the world. It has been well-known for many decades and is nowadays one of the most regulated mycotoxins in food. Today when fruit and vegetables are traded internationally more than ever before, the quality of the goods might fall victim for careless storage during logistics. Still, with natural resources becoming scarce, we need to take care of what we got in our reach. Maybe at some point in the future we might have to find a usage for a shipment of apple juice contaminated with patulin. In this study, we focus on finding ways to decrease the amount of patulin in apple juice. By inoculation apples with the mold Penicillium expansum, 3 grades of decay were produced in the fruits. Diameters of lesion that the infection reached were sorted into 25 mm, 35 mm and 45 mm. Using a household fruit juicer these 3 grades of infected apples were juiced separately, to produce 3 juices containing different amounts of patulin. Having these 3 juices, using 5 treatments found in commercial juicing businesses (unfermented, pasteurized, fermented with commercial yeast strains Safale S-04 or Safale US-05, or spontaneously fermented by wild Saccharomyces cerevisiae) could prove if there were any process that would reduce the patulin concentration. Using a common extraction method and a HPLC analysis with a UV diode array detector at 276 nm, it was concluded that both the commercial yeasts lowered the concentration significantly if compared to the unfermented and the pasteurized. A significant difference in patulin concentration was concluded between the 3 degrees of lesion, where the highest grade of decay (45 mm lesion diameter) had the highest levels of patulin in its juice and the lowest grade of decay (25 mm lesion diameter) resulted in the lowest patulin concentration.